Science/Bio/Med Terms

 

 

 

GLOSSARY OF SCIENTIFIC TERMS
Scientific Divisions | Animals | Elements | Ologies | Motion | Particles
absolute zero. The lowest theoretical temperature (0K = -273.16°C) where all molecular activity ceases.
acceleration.  Rate of change of velocity.
acid.  A compound that yields hydrogen ions (H+) when in aqueous solution.  Acids have a sour taste and turn blue litmus red.
activation energy.  The energy required to initiate a chemical reaction.
adiabatic system.  A system that neither gains or looses heat.
alcohol.  Organic compound used in gums, resins, dyes and perfumes.  Fermentation produces ethanol not alcohol.
alkali.  A base that is soluble in water.
allele.  Gene variant.
allotrope.  Element with more than one natural form.
alloy.  A substance formed by the combination of two or more elements, at least one of which must be a metal.
amino acids.  Carbon, hydrogen, oxygen and nitrogen compounds the composition of which are determined by genes.
anion.  A negative ion.
atomic number.  The number of protons in an atom..
atomic symbol.  The letters representing each of the elements.
atomic weight.  The average weight of an atom.
atoms.  Composite particles of protons, neutrons and electrons.  The smallest part of a substance that can take part in a chemical reaction.  
baryon.  A three quark hadron.  The most common baryons are protons and neutrons.
base.  A compound that yields hydroxide (OH- ) ions when in aqueous solution.  Bases have a bitter taste, feel greasy and turn red litmus blue.
biosynthesis.  The production of cellular material.
boiling point.  The temperature at which a liquid turns to a vapour.
bond.  A chemical link between atoms.
capacitance.  The ability to store an electric charge.
carbohydrates.  The major energy source within plants and animals: sugars, starches and glucose polymers.
carbon.  The basic element in all organic compounds.
catalyst.  A substance that reduces the activation energy of a reaction.
cation.  A positive ion.
cell.  The smallest independent part of an organism.
chain reaction.  Polymerisation initiated by the bonding of a free radical with a monomer.
charge.  The amount of unbalanced electricity in a system.  Either positive or negative.
chemical equation.  The mathematical representation of a chemical reaction.
chemical (empirical) formula.  The ratio of elements in a substance.  For example: the chemical formula of common salt is NaCl, sodium and chlorine in a ratio of 1:1.
chemical reaction.  The transformation of substances by the rearrangement of their atoms.
chromosomes.  DNAmolecules that contain the set of instructions required to build and maintain cells.
compound.  A substance containing more than one element.
conduction.  Heat or electricity transfer through molecular interaction, eg: heat passing along a metal bar.
convection.  Heat transfer through the movement of a fluid, eg: warm air rising.
coulomb attraction.  Electrostatic attraction between bodies of opposite charge
covalent bond.  A bond formed between atoms that share electrons.
crystal.  Solid substance with a regular geometirc arrangement of atoms.
cytosol.  Jelly-like substance within cells.
density.  The mass per unit volume in a substance.
diffraction.  The deviation in the path of a wave that encounters the edge of an obstacle.
diffusion.  The random movement of molecules within a fluid.
DNA: Deoxyribonucleic acid.  Twisted helical polymer chains.  See chromosomes.
elasticity.  The ability of a body to regain its original shape after deformation.
electric current.  A flow of electrons through a conductor, the size of the current is proportional to the rate of electron flow.
electrons.  Negatively charged atomic particles.
electromagnetic waves.  Waves with both an electric and magnetic component.  They are: radio, micro, infra-red, visible light, ultraviolet, X and gamma rays.
electrolyte.  An ion solution that is an electrical conductior.
element.  A substance composed of atoms all with the same atomic number.  A substance that cannot be split chemically into smaller substances.
endothermic reaction.  A reaction in which heat is absorbed ie: melting or boiling.
energy.  The capacity to do work.  Work is done by transferring energy from one form to another.  For example the chemical energy in a fuel is converted to thermal energy as it burns.  See also Laws of Thermodynamics.
entropy. The state of disorder in a thermodynamic system: the more energy the higher the entropy.
enzymes.  Biological catalysts, proteins that control specific processes within the body.
equilibrium.  A stable situation in which products and reactants are balanced.
evaporation.  The change of state of a substance from a liquid to a gas below its boiling point.
evolution.  Natural selection, the survival of the fittest, is the driving force behind evolution and is measured by a species viability and fecundity. Governed by Darwin's theory of evolution by natural selection:
1.    The distinguishing features (characters) of an organism may affect it fitness.
2.    The design of an species (its morphology) differs within a population and may improve its fitness.
3.    An organism may be susceptible to a lack of vital resources, predation and disease reducing its fitness.
4.    The characters that improve fitness must be inherited.  Individuals that inherit these characters will survive at the expense of those who do not.
5.    Mutation is essential for evolution: the inheritance of non-standard genes that improve fitness.
Note: Fitness is the ability to survive and reproduce, not necessarily a measure of physical fitness.
exothermic reaction.  A reaction from which heat is lost eg: combustion.
fats.  Molecules of fatty acids or glycerol.  Used as a food store, insulation and for shock absorption.
fecundity.  The ability to breed.
field.  A region in space that is defined by a vector function.  Common fields are: gravitational, electric and magnetic.
fission.  Splitting the nucleus of an atom into smaller units.
fluid.  A liquid or gas.
force.  An action (transfer of energy) that will accelerate a body in the direction of the applied force.  See Newtons Laws of Motion.
free radical.  A highly reactive molecule used to start the production of a polymer chain.
frequency.  The rate as which periodic motion repeats itself.
friction.  The interaction between surfaces: a measure of the resistance felt when sliding one body over another.
fundamental particles.  Those particles that are not known to contain any smaller components: leptons, quarks and gauge bosons.
fusion.  1.  Change of state of a substance from a solid to a liquid.  2.  The joining together of two atomic nuclei.
gametes.  Sex cells (spermatozoa or ova) that carry the genes donated by each parent.
gauge bosons.  Particles that mediate the transfer of energy between other particles: protons, gravitons, W and Z particles.
gene.  A unit of inheritance.  A section of DNA.  comprising a sequence of four bases: adenine, guanine, cytosine and thymine.
genome.  The collective noun for a set of genes.  The human genome contains 100 000 genes.
gravity.  The attraction that all bodies have for one another.
hadrons.  Quark composites: mesons and baryons. Protons and neutrons are the most common hadrons.
half-life.  The time taken for the level of radioactivity in an element to halve.
halogen.  Highly reactive gases forming group 7 of the periodic table.
heat.  The internal energy of a body (substance).
hydrocarbon.  Compounds containing only hydrogen and carbon atoms.
ideal gas.  One which obeys the ideal gas law.  At low pressures, real gases behave like ideas gases.
inertia.  Tendency of a body to remain at rest or move in straight line.
inheritance.  The features of an organism are determined by a set of chromosomes.  These originate in the parents and are passed on to an offspring during fertilisation. It follows then that since chromosomes are inherited, all the features of an organism must be inherited.
ion.  Atom with an unbalanced electrical charge caused by the loss or gain of one or more electrons.
ionic bond.  An bond formed by the electro-magnetic attraction between ions of opposite charge.
isomer.  Chemical compounds with the same composition but different shapes.
isomeric structure.  The shape of a molecule.  The isomeric structure is determined by the order in which the atoms are bonded together.
isotope.  An element that has more or less neutrons than normal.  Many isotopes are radioactive.
kinetic energy.  The energy possessed by a body in motion.
latent heat.  The amount of energy required to change a solid to a liquid or liquid to a gas.
Laws of Themodynamics.
1.    The amount of energy in the universe is fixed.  It cannot be created or destroyed only changed from one state to another.
2.    Heat cannot pass from a cold to a hot body.  The opposite condition where heat always flows from a hot to a cold body is valid for the whole universe.
lens.  Light modifier.  Convex lenses focus and concave lens diffuse light waves.
leptons.  Fundamental particles that are relatively non-reactive and capable of an independent existence: electrons, muons, tau particles and neutrinos.
light.  The visible part of the electromagnetic spectrum: red, orange, yellow, green, blue, indigo and violet.  White light is a combination of all the above colours.
magnet.   A body which produces a magnetic field.  All magnets are di-pole and follow the rule that like poles repel and unlike poles attract.
mass.  The quantity of matter in a body.
mesons.  Two quarkhadrons, the product of radioactive decay.
metals.  Elements characterised by their opacity, malleability and thermal and electrical conductivity.
mitochondria.  Organelles that convert glucose into energy.
molecular formula.  The number and types of atom in a molecule.  For example the molecular formula of methane is CH4, one atom of carbon and four atoms of hydrogen.
molecule.  A group of atoms bonded together.  It is the smallest part of a substance that retains the chemical properties of the whole.
moment.  A rotating effect.  See torque.
momentum.  The product of mass times velocity.  Momentum is conserved in any system of particles.
monomers.  Small molecules that link together to form a polymer.
neutralization.  A reaction in which the characteristics of an acid or base disappear.
neutrons.  Particles with zero charge forming part of an atomic nuclei. 3 quarkhadrons.
Newtons Laws of Motion.  Classical laws which enable the prediction of the path of any object from a grain of sand to entire galaxies:
1.    A body will remain at rest or move with a constant velocity unless acted upon by an outside force.
2.    The acceleration of a body is proportional to the applied force.  This is expressed by the universal formula:  Force = mass × acceleration.
3.    For every action there is an equal and opposite reaction.
noble gases.  Elements with zero valency.  They form group 0 in the periodic table and are non-reactive.
nucleus.  1. Organelle containing the chromosomes.  2.  That part of an atom containing the protons and neutrons.
organelles.  Specialized organs within cells.
organic compounds. Substances that contain Carbon.
ozone.  An isotope of oxygen that blocks ultra-violet radiation.  Normally found in the stratosphere.
pH Scale.  The strength of acids and bases.  Pure water has a pH value of 7, acids have a lower value and bases higher.
phase changes.  Freezing or boiling.
photo-synthesis.  The conversion of water and carbon-dioxide by plants into glucose and oxygen.  Light is used as an energy source.
photons.  Fundamental quantum particles.  It is the interaction of photons with other particles that drives the universe.
polymerisation.  The repetitive bonding of small molecules (monomers) to produce large molecules (polymers).
polymers.  Long chain molecules such as PVC, nylon or DNA produced by the polymerisation of monomers.
potential difference.  The voltage difference between two points.  Electricity flows from a high to low level of potential.
potential energy.  Amount of useable energy within a body at rest.
power.  Amount of work done per second.
products.  The substances produced in a chemical reaction.
proteins.  Amino acid polymers with specific biological functions, especially the growth, regeneration and repair of cells.
protons.  Positively charged particles forming part of atomic nuclei. 3 quarkhadrons.
quantum theory.  The theory that energy can only be absorbed or radiated in discrete values or quanta.  All particles are subject to quantum theory. Click here to find out more.
quarks.  Fundamental particles, incapable of  independent existence, that combine to form particles such as protons and neutrons.
radiation.  1.  Transfer of heat between bodies without a change in the temperature of the intervening medium.  2.  Any release of energy from its source.
radioactivity.  The spontaneous release of energy from atomic nuclei.
reactants.  The substances that take part in a chemical reaction.
refraction.  The deflection of a wave as it passes from one medium to another, eg through a lens.
relative atomic mass (RAM).  The mass of an atom relative to one atom of carbon.  Carbon has a RAM of 12.
relativity.  The relative values of time, motion, mass and energy of a body in motion. Click here for more information
reproduction.  Reproduction is the process by which a new organism is produced.  The first stage in the production of any organism is the fertilisation of an ova by spermatozoa (or spores on the case of plants).  Fertilisation produces a single cell called a zygote which contains all the information required to build the adult organism.  The progression (growth) from zygote to adult is achieved through cell division.
resistance.  Opposition to current flow in a conductor.
resonance.  A state where the natural frequency of a body equals an applied frequency.
respiration.  The production of energy by the oxidisation of glucose.
scalar.  A quantity that is defined by its magnitude only (ie energy, temperature).
simple harmonic motion.  A repeating motion about a central equilibrium point (pendulum, weighted spring).
special relativity.  The observable effects on a body in motion.  As velocity increases, time slows down, mass increases and lengths contract.
speciation.  A group of organisms that are able to interbreed all belong to the same species.  It follows then that organisms that are unable to interbreed belong to separate species.
specific heat.  The heat capacity of a body.
standard model. The organization and relationships between fundamental particles. Click here for more information.
strain.  The deformation of a body under an applied load.
stress.  The measure of the force acting on a body.
temperature.  How hot one body is when compared to another.
torque.  The tendency of a body to rotate under an applied force..
uncertainty.  It is impossible to know exactly where something is and where it is going. This is a fundamental law of nature has a major effect on quantum theory.
valency.  A measure of the reactivity of an element.
vector.   A quantity that is determined by its magnitude and direction: forces and fields (see scalar).
velocity.  The rate of change of distance with respect to time.
viability.  The ability to survive to adulthood.
viscosity.  The internal friction of a fluid, thick fluids have a high viscosity and thin fluids low.
weight.  The gravitational force exerted on a mass.
work.  The amount of energy transferred to a system.
zygote.  A fertilised egg, the fusion of a male and female gamete.


Glossary of Medical Terms
A
ABT-267: see ombitasvir/VIEKIRA PAK
ABT-333: see dasabuvir/VIEKIRA PAK
ABT-450: see paritaprevir/VIEKIRA PAK

ADVERSE EVENT:  an unwanted side effect of a medication.

ABDOMEN: (adjective ABDOMINAL): the area of the body between the chest and pelvis.
ABSORPTION: the passage of nutrients, drugs, or water from the intestines into the bloodstream.
ABSTRACT: a written summary of the important points of a medical article.
ACCELERATED APPROVAL: FDA regulations governing early marketing approval of promising drugs for life-threatening illnesses.

ACETAMINOPHEN: (also known as paracetamol): an analgesic drug used to relieve pain and reduce fever. Tylenol is the most well-known brand name.
ACQUIRED IMMUNE DEFICIENCY SYNDROME: (AIDS): a syndrome characterized by suppression of the immune system, rendering the body susceptible to various illnesses; the late, symptomatic stage of HIV disease.

ACTIGALL: see ursodiol.

ACTIVE INFECTION: an infection in which a disease-causing microorganism is actively replicating and infecting new cells.

ACUPRESSURE: a traditional Chinese healing technique in which finger pressure is applied to specific points on the body to treat disease and alleviate symptoms.

ACUPUNCTURE: a traditional Chinese healing technique that involves inserting thin needles into different acupuncture points on the body. Acupuncture is believed to improve the flow of qi, the body's vital energy; it is used for many conditions, including pain and addiction.

ACUTE: rapid-onset, short-term initial stage of a disease. Contrast with chronic.

ACUTE HBV: Initial infection with hepatitis  B.

ACUTE HEPATITIS: the initial stage of viral hepatitis following infection. In HCV, acute hepatitis refers to the first six months of infection.

ADA: see Americans with Disabilities Act.

ADEFOVIR: ((ADV) brand name HEPSERA): A nucleoside analogue that is used to treat chronic hepatitis  B. Adefovir is not recommended as a first line of HBV treatment because of the high rate of drug resistance.

ADDITIVE EFFECT: the combined effect of several drugs that is the sum of the effects that would be produced by each of the drugs in the absence of the others.

ADHERENCE: following a prescribed treatment regimen, including correct dosage, timing, and number of doses per day.

ADJUNCT THERAPY: therapy given in addition to a primary treatment.

ADRENAL GLAND: one of a pair of glands located above the kidneys. The adrenal medulla produces hormones such as adrenaline  (epinephrine), while the adrenal cortex produces corticosteroids and androgens.

ADVERSE REACTION: (SIDE EFFECT): an undesired action or effect of a drug or other treatment.

AEROBIC EXERCISE: a type of exercise  (e.g., running, swimming) that makes the heart and lungs work harder to supply the muscles with oxygen.

AFP: see alpha-fetoprotein.

AIDS: see acquired immune deficiency syndrome.

ALANINE AMINOTRANSFERASE: (ALT; formerly SGPT): an enzyme (also called alanine transaminase) produced in the liver when the membranes of liver cells break down. ALT levels are measured to help assess the degree of liver damage and determine how well HCV treatment is working. A normal level is below 48 IU/L.

ALBUMIN: a blood protein produced by the liver that plays a role in maintaining normal blood volume. A low albumin level is associated with liver cirrhosis. A normal level is 3.2 to 5.0g.

ALCOHOLISM: a disorder characterized by excessive consumption of and dependence on alcohol.

ALKALINE PHOSPHATASE: (AP): an enzyme found in various body tissues and fluids. Abnormal alkaline phosphatase levels are associated with liver disease and bone and muscle damage. A normal level is 35 to 125 IU/L.

ALKALOID: an organic compound found in plants.

ALLERGY: an abnormal immune response to an antigen (allergen) that does not normally cause an adverse reaction (e.g., animal dander, pollen). Allergic reactions are caused by the release of histamine by mast cells, a type of white blood cell. Allergic symptoms may include runny nose (rhinitis), skin rash, asthma, and anaphylactic shock.

ALLOGRAFT: a transplant of genetically matched cells, tissues, or organs between two members of the same species.

ALLOPATHY: (adjective ALLOPATHIC): Western medicine; the conventional medical practices used most often in the U.S.

ALOPECIA: hair loss.

ALPHA INTERFERON: see interferon-alpha.

ALPHA-FETOPROTEIN: (AFP): a protein, measurable in the blood, that is often elevated in people with liver cancer.

ALPHA LIPOIC ACID: (THIOCTIC ACID): a compound that enhances the antioxidant effect of vitamin C and vitamin E, and may help reduce liver inflammation and protect liver cells from damage.

ALT: see alanine aminotransferase.

ALTERNATIVE THERAPY: any type of treatment that is not considered standard or conventional practice in a given culture. In Western countries, traditional Chinese medicine, homeopathy, naturopathy, and chiropractic are considered alternative therapies.

AMENORRHEA: absence of menstrual periods.

AMERICANS WITH DISABILITY ACT: (ADA): a federal law that requires employers to offer certain protections and benefits (including "reasonable accommodation") to persons with disabilities that substantially limits major life activities.

AMINO ACID: an organic compound that is a basic structural unit of peptides and proteins. There are over 100 amino acids, eight of which are essential for human metabolism.

AMINOTRANSFERASE: (TRANSAMINASE): an enzyme (e.g., ALT,  AST) produced by the liver that catalyzes the transfer of amino acids. Abnormally high aminotransferase levels in the blood suggest liver damage.

AMMONIA: a toxic metabolic byproduct that is normally excreted in the urine.

AMNESIA: memory loss.

AMPLICOR/COBALT AMPLICOR: brand name of a PCR-based viral load test for HCV and HIV.

ANA: see antinuclear antibody

ANALGESIC: a drug or therapy that reduces pain.

ANALINGUS: (RIMMING): oral/anal sex.

ANECDOTAL: evidence based on reports of specific individual cases rather than controlled clinical studies.

ANEMIA: (adjective ANEMIC): reduced number of red blood cells or reduced ability of blood to carry oxygen. There are several types of anemia, all with different causes. Symptoms may include fatigue, weakness, pale skin, and difficulty breathing.

ANESTHESIA: (adjective ANESTHETIC): an agent that controls pain. Localized anesthesia blocks pain in a given area; general anesthesia produces unconsciousness.

ANEURYSM: an abnormally stretched, dilated section of a blood vessel that is prone to bursting.

ANGINA PECTORIS: chest pain that occurs when the heart muscle receives inadequate oxygen.

ANOREXIA: loss of appetite for food.

ANTIBIOTIC: an agent that kills or inhibits the growth of bacteria.

ANTIBODY: (IMMUNOGLOBULIN): a protein produced by plasma cells (a type of immune system white blood cell) when they encounter foreign invaders. Specific antibodies bind to specific invaders, or antigens, and target them for destruction. The presence of antibodies indicates current infection with or past exposure to a pathogen.

ANTIBODY POSITIVE: (SEROPOSITIVE): the presence in the blood of antibodies against a specific pathogen such as HCV.

ANTIBODY TEST: an assay that detects the presence of antibodies in a blood sample; ELISA and RIBA tests are used to detect HCV antibodies.

ANTICOAGULANT: a drug that reduces or delays blood coagulation or clotting.

ANTICONVULSANT: a drug that prevents or reduces convulsions or seizures.

ANTIDEPRESSANT: a drug that elevates the mood and alleviates mental depression. There are several types, including selective serotonin reuptake inhibitors (SSRI's), MAO inhibitors, and tricyclics.

ANTIEMETIC: a drug that relieves nausea and vomiting.

ANTIFIBROTIC: a drug or other agent than prevents or reduces the development of liver fibrosis or cirrhosis.

ANTIGEN: any agent or substance that stimulates an immune response. Antigens are often foreign invaders such as bacteria or viruses.

ANTIHISTAMINE: a drug that blocks the action of histamine, a chemical messenger in the body. Antihistamines are used to prevent or alleviate allergic reactions and to reduce stomach acid production.

ANTINUCLEAR ANTIBODY: An antibody that attacks cell nuclei.

ANTIOXIDANT: a substance that reduces oxidation by binding with and neutralizing free radicals. The body produces natural antioxidants, and they are also available in foods and dietary supplements (e.g., vitamin E, selenium).

ANTIRETROVIRAL: a drug that suppresses the activity or replication of retroviruses. Different types of antiretroviral drugs (e.g., reverse transcriptase inhibitors, protease inhibitors) interfere with various stages of the virus life cycle.

ANTISENSE COMPOUNDS: Compounds that target gene sequences associated with diseases to interfere with the disease process.

ANTISENSE OLIGONUCLEOTIDE: an agent that blocks the synthesis of disease-causing proteins by binding with and preventing translation of RNA (genetic material). HCV antisense oligodeoxynucleotides are directed against a specific HCV genetic sequence and inhibit viral gene expression.

ANTIVIRAL: a drug that suppresses the activity or replication of viruses.

ANXIOLYTIC: a drug that helps relieve mental anxiety.

APLASTIC ANEMIA: anemia due to a reduced level of red blood cells caused by the inability of stem cells in the bone marrow to produce new cells. Certain drugs suppress the bone marrow and can lead to aplastic anemia as a side effect.

ARM: a group of participants in a clinical trial who receive the same treatment (or placebo).

ARTERIOGRAPHY :(ANGIOGRAPHY): examination of arteries (after injection of a dye) to look for damage and blockages.

ARTHRALGIA: joint pain.

ARTHRITIS: joint inflammation.

ASCITES: accumulation of fluid in the abdominal (peritoneal) cavity. Ascites may be a symptom of advanced liver disease with decompensated cirrhosis.

ASPARTATE AMINOTRANSFERASE :(AST, formerly SGOT): an enzyme (also called aspartate transaminase) produced in the liver. When liver cells are damaged, AST is released. Elevated levels may indicate liver disease, but are also seen in people with muscle damage. A normal level is below 42 IU/L.

ASSAY: a test, especially one used to detect the presence or amount of an agent in the blood or body tissues.

AST: see aspartate aminotransferase.

ASTRAGALUS: an herb used to stimulate the immune system. It is an ingredient in many Chinese herbal formulas.

AS-TREATED ANALYSIS: a method of analyzing the results of a clinical trial that includes only participants who successfully complete a course of the treatment, excluding those who drop out early. Contrast with intent-to-treat analysis.

ASYMPTOMATIC: not feeling or showing outward symptoms or signs of a disease.

ATHEROSCLEROSIS: a condition in which blood vessels harden and lose their elasticity due to the build-up of fatty material (plaques).

AUTOANTIBODY: an antibody that targets the body's own tissues.

AUTOIMMUNE RESPONSE :(AUTOIMMUNITY): a condition in which a person's immune system produces antibodies that attack the body's own tissues. Several conditions associated with hepatitis C (e.g., lichen planus, Sjögren's syndrome) appear to have an autoimmune aspect.

AUTOIMMUNE THYROIDITIS: an inflammatory, autoimmune condition in which the immune system attacks the thyroid gland.

AYURVEDA: a system of traditional medicine practiced in India.



B
BACTERIUM (plural BACTERIA): a simple single-celled microorganism. Bacteria are classified by their shape (e.g., rod, spirochete), staining properties (Gram positive or Gram negative) and habitat (aerobic, anaerobic).

BASELINE: an initial or known value (e.g., ALT level, HCV viral load) against which later measurements can be compared.

B-CELL (B-LYMPHOCYTE): a type of immune system white blood cell. B-cells mature into plasma cells that produce antibodies.

bDNA: see branched-chain DNA assay.

BECK DEPRESSION INDEX: a written, self-report questionnaire used to gauge clinical depression.

BEHCET'S DISEASE: a disease that presents as ulcerations in the eyes, mouth and genitals but can affect any organ of the body.

BENIGN: a mild, non-lethal illness, especially a non-cancerous tumor. Contrast with malignant.

BIAS: in a clinical trial, a false association that results from the failure to account for some skewing or influencing factor.

BID: taken twice daily.

BILE: a yellowish-green fluid produced by the liver that aids in the digestion of fats and the excretion of toxins.

BILE DUCT: the passage that carries bile from the liver to the small intestine.

BILIRUBIN: a yellowish pigment released when red blood cells are broken down. Normally bilirubin is processed and excreted by the liver. An excess level of bilirubin in the blood (hyperbilirubinemia) may indicate liver damage, and can lead to jaundice (yellowing of the skin and whites of the eyes), pale-colored stools, and dark urine. A normal bilirubin level is below 1.3mg.

BINDING PROTEIN: a protein synthesized by the liver that binds to and transports substances such as vitamins, minerals, hormones, and fats.

BIOAVAILABILITY: the degree to which a drug or other substance is absorbed and circulated in the body.

BIOCHEMICAL RESPONSE : (BIOLOGICAL RESPONSE): a favorable response to treatment as indicated by normalization of blood values (e.g., liver enzyme levels).

BIOFEEDBACK: a technique in which people learn to use signals from their own bodies to influence physiological functions.

BIOFLAVINOID (VITAMIN P): natural pigments found in fruits and vegetables that increase absorption of vitamin C.

BIOLOGICAL RESPONSE: see biochemical response.

BIOPSY (BX): a procedure in which a sample of cells or tissue is taken for laboratory examination. Liver biopsies are used to monitor liver disease progression in people with HCV.

BLINDING: a method of conducting clinical trials in which participants do not know who is taking an experimental treatment, a standard (control) treatment, or a placebo. In a blinded study, the volunteers do not know what treatment (if any) they are receiving. In a double-blind study, neither the volunteers nor the researchers administering the treatment know who is receiving what. Blinding is done to reduce bias in drug trials. In the case of medical necessity, a study may be unblinded to reveal who is receiving what treatment.

BLOOD-BORNE: a pathogen that is transmitted through direct blood-to-blood contact, for example, through sharing dirty needles or through a blood transfusion.

BLOOD TRANSFUSION: the infusion of blood or blood components into an individual for the treatment of a medical condition. Transfusions may be homologous (from a donor) or autologous (previously stored blood from the recipient).

BMI: see body mass index.

BOCEPREVIR : (Victrelis): HCV protease inhibitor taken in combination with pegylated interferon plus ribavirin previously used to hepatitis C.

BODY MASS INDEX (BMI): a measurement of body fat determined by dividing a person's weight (in kilograms) by height (in meters squared).

BODYWORK: healing techniques (e.g., massage therapy, reflexology) that involve manipulating or applying pressure to the body.

BONE MARROW: the soft, spongy material inside certain long bones where blood cells are produced.

BRAIN FOG: mild mental confusion, memory loss, and/or lack of concentration and alertness. May be a symptom of toxic chemical build-up due to impaired liver function. See hepatic encephalopathy.

BRANCHED-CHAIN DNA ASSAY (bDNA): a test that measures the amount of virus (viral load) in plasma or tissues using a chemical signal emitted by viral genetic material.

BREAKTHROUGH: the return of detectable viral load or high ALT levels in a person who had previously achieved a good virological or biochemical treatment response.

BUDDING: the emergence of newly produced virus particles through a host cell membrane.

BUN: (Blood urea nitrogen): a test that measures the amount of a certain waste product (nitrogen) excreted by the kidneys.

BUPLEURUM: an herb traditionally used in Chinese medicine to treat liver conditions.

BX: see Biopsy.



C
CADAVER: the body of a dead person.
CADAVERIC DONOR: a recently deceased person who has donated an organ or tissue.
CANCER: a malignant neoplasm or tumor characterized by abnormal cell proliferation. Types include carcinoma (which affects epithelial cells), sarcoma (which affects soft tissues), lymphoma and leukemia (which affect lymphoid tissue), and glioma (which affects brain tissue).

CANITIES: a condition that causes premature graying of the hair.

CAPILLARIES: tiny blood vessels that deliver oxygen and nutrients to and remove waste products from cells.

CARBOHYDRATE: an organic molecule composed mainly of carbon, hydrogen, and oxygen atoms. Carbohydrates constitutes a major class of nutrients, and are present in foods such as bread and pasta.

CARCINOGEN: an agent that promotes the development of cancer.

CARCINOMA: a malignant tumor of the epithelial cells that line body surfaces and cavities. Carcinoma in situ refers to an early stage of cancer that has not invaded surrounding tissues.

CARDIAC: having to do with the heart.

CARDIOVASCULAR: having to do with the circulatory system (the heart and blood vessels).

CARRIER: a person who does not show symptoms or have active disease, but who carries an infectious organism and can transmit it to others.

CASE STUDY: a description of a specific clinical case, that is, the development of disease and response to treatment in a single individual.

CASUAL CONTACT: non-intimate contact between individuals (e.g., hugging, eating, working together) that does not involve transfer of body fluids and therefore does not pose a risk for transmission of blood-borne diseases.

CATEGORY A, B, C, D, X: an FDA classification for drug safety during pregnancy. Category A drugs have not shown a risk to fetuses in controlled studies. Category X includes drugs which animal and human studies or common experience have shown to cause fetal abnormalities or miscarriages.

CBC: see complete blood count.

CD4 CELL: (CD4 LYMPHOCYTE, T-HELPER CELL): a type of white blood cell that helps the body fight infection.

CD4 CELL COUNT: the number of CD4 lymphocytes in one cubic millimeter (mm3) of blood. The CD4 count is one indicator of the progression of HIV disease. A CD4 count below 200 cells/mm3 is a diagnostic criteria for AIDS.

CD8 CELL (CD8 LYMPHOCYTE): a type of white blood cell that helps regulate and/or carry out the body's immune response. CD8 cells include T-suppressor cells and cytotoxic T-lymphocytes.

CDC: see Centers for Disease Control and Prevention.
CELL: the basic unit of living organisms. A cell contains a nucleus and a cell wall (in plants) or a cell membrane (in animals) which surrounds the cellular material, called cytoplasm.
CENTERS FOR DISEASE CONTROL AND PREVENTION: (CDC): the U.S. federal government agency within the Department of Health and Human Services that monitors the occurrence of diseases and develops policies for preventing disease and maintaining the health of the population.

CENTRAL NERVOUS SYSTEM (CNS): the brain and spinal cord.

CEPLENE: see histamine dihydrochloride.

CEREBRAL VASCULITIS a disorder characterized by inflammation and cell death in arteries.

CEREBROVASCULAR: having to do with the flow of blood to the brain.

CEREBROVASCULAR ACCIDENT: see stroke.

CESAREAN SECTION (C-SECTION): a delivery procedure that involves making an incision through the abdominal wall to remove an infant from the uterus (womb).

cEVR: see complete early virological response.

CFIDS: chronic fatigue immune dysfunction syndrome. See chronic fatigue syndrome.

CHEMOKINE: a chemical, secreted by certain immune system cells, that acts as a messenger between cells and stimulates the activity of cells.

CHEMOTHERAPY: the use of drugs to treat disease.

CHIROPRACTIC: a system of treatment based on manipulation of the spine.

CHOLAGOGUE: an agent (especially an herb) that improves bile flow.

CHOLANGITIS: inflammation of the bile duct, often characterized by jaundice.

CHOLESTASIS: obstruction of the flow of bile between the liver, the gall bladder, and the small intestine.

CHOLESTEROL: a fatty substance in animal tissue that is an essential component of cell membranes, certain hormones, and nerve fiber insulation. Cholesterol is manufactured by the liver, and is also present in certain foods. There are two primary types of cholesterol in the blood, low-density lipoprotein (LDL), which is considered a risk factor for heart disease; and high-density lipoprotein (HDL), which is considered protective.

CHOOSE MYPLATE: a visual diagram showing which foods are part of the daily recommended amounts included in a balanced diet. A healthy diet includes 6 to 11 servings of breads and grains 3 to 5 servings of vegetables; 2 to 4 servings of fruit; 2 to 3 servings of meat, fish, beans, or nuts; 2 to 3 servings of dairy products; and limited fats and oils.

CHRONIC: a long-term or persistent disease. Contrast with acute.

CHRONIC ACTIVE HEPATITIS: a condition in which HCV or HBV continues to replicate and infect new cells after six months.

CHRONIC FATIGUE SYNDROME (CHRONIC FATIGUE IMMUNE DYSFUNCTION SYNDROME, CFIDS): an illness characterized by prolonged fatigue, neurological problems, joint and muscle pain, and/or impairment of the ability to function normally for six months or longer.

CHRONIC HBV: a term for lifelong infection of hepatitis B.

CHRONIC HEPATITIS: liver inflammation lasting longer than six months.

CIRRHOSIS: a type of liver damage in which normal liver cells are replaced with fibrous scar tissue. In compensated cirrhosis, the liver is damaged but can still function. In decompensated cirrhosis, liver function is severely impaired and scar tissue interferes with normal blood flow through the liver, potentially leading to bleeding varices, ascites, "brain fog," and other symptoms.

CLEARANCE: removal or elimination, e.g., of a virus or drug from the body.

CLINICAL: relating to the treatment of patients. A clinical observation is based on a person's observed condition and symptoms, as distinguished from laboratory findings.

CLINICAL TRIAL (CLINICAL STUDY): an organized procedure for determining the effectiveness of a new drug or therapy by administering the agent to volunteers under controlled conditions. In many clinical trials, new treatments are compared against older standard treatments or an inactive substance (placebo).

CLOT: a sticky mass of coagulated blood cells and platelets.

CLOTTING FACTOR (COAGULATION FACTOR): a protein (e.g., fibrinogen, prothrombin, Factor VIII) that is necessary for normal blood clotting. Several clotting factors are synthesized by the liver and production may be impaired when the liver is damaged. People with clotting factor deficiencies may experience prolonged bleeding and easy bruising.

COBALAMIN: see vitamin B12.

COEMZYME Q10: an antioxidant agent that is necessary for the proper activity of certain enzymes.

COFACTOR: a factor that influences the progression of a disease or the action of a disease-causing agent.

COFORMULATION: a combination of two or more medications combined into one medication. Examples include sofosbuvir/ledipasvir (Gilead) and ABT-450/ritonavir/dasabuvir (Abbvie).

COGNITIVE DYSFUNCTION: reduction in mental functioning and ability to carry out tasks that require thinking, planning, and memory.

COHORT: a group of individuals in a study who share a demographic, clinical, or other characteristic.

COINFECTION: concurrent infection with more than one disease-causing organism (e.g., HCV and HIV).

COLONY-STIMULATING FACTOR (CSF): a cytokine responsible for regulating the production of white blood cells. Types include granulocyte colony-stimulating factor (G-CSF) and granulocyte macrophage colony-stimulating factor (GM-CSF).

COLOSTRUM: breast fluid produced during the first few days after a baby's birth (prior to milk production) that contains proteins, immunoglobulins, and immune cells.

COMA: a state of deep unconsciousness; a vegetative state.

COMBINATION THERAPY: use of two or more drugs together to improve the effectiveness of treatment. In HCV treatment, the term most often refers to the use of two or more HCV inhibitors with and without ribavirin. Contrast with monotherapy. Contrast with monotherapy.

COMPASSIONATE USE: an FDA classification that allows individuals to use experimental drugs prior to their approval for a serious illness for which there is no other suitable treatment.

COMPENSATED CIRRHOSIS: see cirrhosis.

COMPLEMENTARY THERAPY: an alternative therapy that is used in conjunction with a standard Western treatment.

COMPLETE BLOOD COUNT (CBC): an inventory of the cellular components of the blood, including red blood cell count, hematocrit and hemoglobin, white blood cell count, and platelet count.

COMPLETE EARLY VIROLOGICAL RESPONSE (cEVR): HCV RNA negative at treatment week 12.

COMPUTED TOMOGRAPHY SCAN: (CT SCAN): a method of viewing the soft tissues of the body using X-rays.

CONDOM: a sheath made of latex, polyurethane, or animal membrane that is worn over the penis to hold ejaculated semen. Condoms are used to prevent pregnancy; latex and polyurethane condoms also protect against HIV, HCV and certain other sexually transmitted diseases. The "female condom" (Reality) is an internal pouch worn inside the vagina or anus.

CONFIDENCE INTERVAL: a statistical measure of the likelihood that an experimental result is "true" and not the result of chance alone.

CONGENITAL: present from birth.
CONGESTIVE HEART FAILURE: heart dysfunction that leads to a build-up of fluids in the body.

CONJUNCTIVITIS: inflammation of the conjunctiva, a membrane that covers the eye and lines the eyelid.

CONSENSUS INTERFERON: a preparation that contains a variety of different types of interferon.

CONTRACEPTION: birth control; a device or method that prevents conception (fertilization), implantation, or successful gestation.

CONTRAINDICATION: any circumstance or condition that makes a drug or other method of treatment inadvisable in a particular case.

CONTROL ARM: a comparison group in a clinical trial that is used to verify an experimental result. A control group is typically given an older standard treatment or a placebo rather than the new experimental treatment under study.

CONTROLLED TRIAL: a clinical trial in which a group receiving an experimental treatment is compared to a control group that is given a standard treatment or a placebo.

COPEGUS: Genentech/Roche’s brand of ribavirin. see RIBAVIRIN.

CORE: the inner part of a virus that contains its genetic material.
CORONARY ARTERY DISEASE: damage to or blockage of the arteries that provide blood to the heart muscle.

CORTICOSTEROID: a steroid hormone (e.g., prednisone, cortisone) produced by the cortex of the adrenal gland or manufactured synthetically. Corticosteroids have anti-inflammatory and immunosuppressive properties, and are used to treat a variety of conditions.

CREATININE: a metabolic byproduct produced by muscles; high levels in the blood may indicate kidney dysfunction.

CREST SYNDROME: a type of scleroderma characterized by a variety of different symptoms (primarily calcinosis, Raynaud's phenomenon, esophageal dysfunction, sclerodactyly, and telangiectasia).

CRYOGLOBULIN: an abnormal immune protein.

CRYOGLOBULINEMIA: a condition in which cryoglobulins form in the blood. When the blood is cooled, the cryoglobulins clump together, causing the blood to thicken and restricting blood flow. Essential mixed cryoglobulinemia occurs in many people with HCV, although most do not experience symptoms.

CRYOSURGERY: removal of damaged or cancerous tissue by freezing.

CT SCAN: see computed tomography scan.

CULTURE: a method of growing a microorganism in a laboratory.

CUNNILINGUS: oral sex on a woman; contact between the mouth and the vulva or vagina.

CUTANEOUS: relating to the skin.

CYSTEINE: an amino acid; one of the building blocks of glutathione.

CYTOKINE: a chemical messenger (e.g., interferon, interleukin, tumor necrosis factor) produced by white blood cells. Cytokines coordinate several aspects of the immune response, including stimulating antibody production and activating killer T-cells.

CYTOPENIA: low levels of blood cells.

CYTOPLASM: the material that makes up the interior of a cell.

CYTOPROTECTIVE: an agent that protects cells from damage.

CYTOTOXIC T-LYMPHOCYTE (CTL, KILLER T-CELL): a type of CD8 white blood cell that targets and kills cells infected with viruses, bacteria, parasites, and other microorganisms.

D
DAA’s: see direct-acting antivirals.

DACLATASVIR: (formerly BMS-790052) is an experimental drug candidate for the treatment of hepatitis C. It is being developed by Bristol-Myers Squibb. Daclatasvir's mechanism of action involves inhibition of the HCV structural protein NS5A. Recent research suggests that it targets two steps of the viral replication process, enabling rapid decline of HCV RNA.

DASABUVIR:(formerly ABT-333) is an HCV polymerase inhibitor.  It is part of the combination of brand name VIEKIRA PAK used to treat hepatitis C.

DATA (singular DATUM): factual information, especially results of an experiment or clinical trial.

DATA AND SAFETY MONITORING BOARD (DSMB): an independent group of community representatives and clinical trial experts that evaluates clinical trials for safety and ethics. DSMBs typically examine interim data as a trial progresses and determine whether it should be stopped or allowed to continue based on safety issues and risk-benefit analysis.

DIDANOSINE (ddi, DDI): an HIV medication (brand name VIDEX and VIDEX EC). It is a reverse transcriptase inhibitor, used in combination with other antiretroviral drug therapy as part of active antiretroviral therapy (ART).  Ribavirin should be avoided if DDI is being used to treat HIV due to the risk of developing lactic acidosis.

DECOMPENSATED CIRRHOSIS: see cirrhosis.

DECOMPENSATION: a failure of the liver to compensate for damage or injury; decrease or breakdown of liver function.

DEHYDRATION: loss or lack of water in the body. Dehydration may result from prolonged vomiting or diarrhea, and may disrupt many bodily processes.

DELIRIUM: a state of mental confusion, typically acute and rapid in onset that may be caused by factors including disease, drug use, or high fever.

DELTA HEPATITIS: see hepatitis D.

DEMENTIA: chronic loss of mental capacity. Dementia may involve progressive deterioration of thinking, memory, and motor function, and may also be associated with personality changes and psychological symptoms such as depression.

DEMOGRAPHICS: the characteristics of a population (e.g., sex, race, age).

DENTAL DAM: a flat square of latex or plastic, traditionally used for dental surgery, that can be used to protect against the spread of sexually transmitted diseases during oral sex.

DEOXYRIBONUCLEIC ACID (DNA): a double-stranded nucleic acid that encodes genetic information. DNA is made up of four chemical building blocks (nucleotides): adenine, cytosine, guanine, and thymine.

DEPRESSION (DYSTHYMIA): a mood disorder characterized by prolonged sadness or grief.

DETOXIFICATION: removal of toxic (poisonous) substances. Detoxification of the blood is an important function of the liver.

DIABETES MELLITUS (DM): a disease caused by insufficient insulin production or lack of responsiveness to insulin. Type 1 (insulin-dependent or juvenile-onset) diabetes results from an inability of the body to produce insulin. Type 2 (non-insulin-dependent or adult-onset) diabetes occurs later is life and is associated with decreased insulin production or insulin resistance.

DIAGNOSIS: the determination of the existence of a disease or condition. Diagnosis generally involves an evaluation of a person's medical history, clinical symptoms, and laboratory test results.

DIALYSIS: a method for filtering waste from the blood that replaces the function of the kidneys that are not working properly.

DIARRHEA: frequent, loose bowel movements. Diarrhea may be caused by a variety of factors, including microorganisms and as a side effect of certain drugs. Persistent diarrhea can lead to dehydration and inadequate nutrient absorption.

DIETITIAN: a medical professional specializing in dietetics, the study of nutrition and the use of special diets to prevent and treat disease.

DIGESTIVE SYSTEM: the organs (mouth, pharynx, esophagus, stomach, small intestine, large intestine, and anus) associated with ingestion and digestion of food.

DIRECT-ACTING ANTIVIRALS (DAA’s): there are at least 4 categories of direct antivirals—protease inhibitors, polymerase inhibitors (nucleoside and non-nucleoside inhibitors) and NS5a inhibitors. DAA’s target and inhibit viral enzymes that are important for replication of hepatitis C. Also called HCV inhibitors

DISCORDANT: not having the same serostatus, for example a couple in which one partner is HCV positive and the other is HCV negative.

DIURETIC: an agent that increases loss of water from the body through urination.

DM: see diabetes mellitus.

DNA: see deoxyribonucleic acid.

DOSAGE: the amount of a drug that is given at one time.

DOSE-RANGING TRIAL: a clinical trial in which different doses of a drug are compared to determine which dosage has the best balance of effectiveness and acceptable side effects.

DOSHA: one of the three bodily humors (vata, pitta, and kapha,) recognized in Ayurvedic medicine.

DOUBLE-BLIND: see blinding.

DRUG-DRUG INTERACTION (DDI): a reaction that can occur when multiple drugs are taken together or drugs are taken with certain herbs or foods. Drug interactions may enhance or reduce the action of a drug and may increase its side effects, and could potentially cause life-threatening reactions.

DRUG RESISTANCE: the loss of drug effectiveness of a drug that had previously been able to control or kill an organism such as a virus.

DX: abbreviation for diagnosis.

DYSFUNCTION: lack or loss of normal function.

DYSPLASIA (adjective DYSPLASTIC): abnormal cell or tissue growth.

DYSTHYMIA: see depression.



E
EARLY VIROLOGICAL RESPONSE (EVR): 2 log10 drop in HCV RNA at treatment week 12.

ECZEMA: a type of skin rash.

EDEMA: swelling caused by accumulation of fluid in body tissues.

EFFICACY: effectiveness; the ability to achieve a desired result.

ELIGIBILITY CRITERIA: the criteria of a clinical trial that includes inclusion and exclusion criteria.

ELISA/ELISA II: see enzyme-linked immunosorbent assay.

EMBOLISM: a blood clot that travels through the bloodstream and becomes lodged in a blood vessel, causing a blockage.

EMPIRICAL: information based on data, not on a theory.

ENCEPHALOPATHY: disease of the brain. See also hepatic encephalopathy.

END-OF-TREATMENT RESPONSE (EOT or ETR): undetectable HCV RNA at the completion of treatment.

ENDOCRINE: endocrine glands are ductless glands that regulate bodily functions via hormones secreted into the bloodstream. The endocrine system includes the hypothalamus, pituitary gland, thyroid, adrenal glands, and gonads (ovaries and testes).

ENDOSCOPY: a method of examining the interior of a body cavity or hollow organ (e.g., esophagus, stomach) using an endoscope, a narrow, flexible fiber optic instrument that conducts light.

ENDOTHELIUM (adjective ENDOTHELIAL): a layer of cells that lines blood and lymph vessels, the heart, and various body cavities.

ENDPOINT: a marker of disease progression or treatment outcome. Endpoints may be clinical manifestations (e.g., disease symptoms, death) or laboratory results such as ALT level or viral load (sometimes called surrogate markers).  An endpoint of a clinical trial is the outcome—such as safety and effectiveness of the study medications.

END-STAGE RENAL DISEASE (ESRD): kidney failure.

ENROLLMENT CRITERIA: factors used to determine whether a person is eligible to participate in a clinical trial. See also inclusion criteria, exclusion criteria.

ENTECAVIR (Brand name BARACLUDE): A nucleoside analogue produced by Bristol-Myers Squibb that is used to treat chronic hepatitis B. It is recommended as a first line of treatment except in people who have developed lamivudine resistance.

ENTERIC: having to do with the intestines.

ENTERIC HEPATITIS: see hepatitis E.

ENVELOPE: the outer coat of a virus.

ENZYME: a protein that induces or accelerates a chemical reaction.

ENZYME-LINKED IMMUNOSORBENT ASSAY (ELISA, ELISA II): a laboratory test used to detect the presence of antibodies in the blood.

EOT: see end-of-treatment response.

EPIDEMIOLOGY: the study of the frequency, distribution, and behavior of a disease within a population.

EPIVIR: see lamivudine.

EPO: see erythropoietin.

EPOGEN: see erythropoietin.

ERADICATION (verb ERADICATE): the complete elimination of an organism from the body.

ERYTHROCYTE: a mature red blood cell. Erythrocytes transport oxygen to the tissues of the body.

ERYTHROPOIETIN (EPOIETIN, EPO): a hormone produced by the kidneys that stimulates the production of red blood cells. Genetically engineered EPO (brand names Procrit, Epogen) is used to treat certain types of anemia.

ESOPHAGUS (adjective ESOPHAGEAL): the swallowing tube; the portion of the digestive tract between the mouth and the stomach.

ESRD: see end-stage renal disease.

ESSENTIAL MIXED CRYOGLOBULINEMIA: see cryoglobulinemia.

ESTROGEN: the primary female sex hormone or a synthetic analog. Estrogens stimulate the development of female secondary sex characteristics and regulate the reproductive cycle in women.

ETIOLOGY: the cause of a disease.

EVR: see early virological response.

EXACERBATE: to worsen or make more severe.

EXPANDED ACCESS: the distribution of an investigational medication to those who are in highest need and who may not qualify for the drug in clinical trials.

EXCLUSION CRITERIA: conditions that disqualify someone from participating in a clinical trial. Contrast with inclusion criteria.

EXPERIMENTAL ARM: the group of participants in a clinical trial that receives the new experimental treatment under study.

EXPERIMENTAL DRUG: a new drug that is being tested as a treatment for a specific condition and has not yet been approved by the FDA for use.

EXTRAHEPATIC: outside the liver.



F
FACTOR VIII: a protein synthesized by the liver that is necessary for proper blood clotting.

FAILURE TO THRIVE: a condition in which an infant loses or fails to gain weight and develops at a slower rate than expected.

FALSE-NEGATIVE: a negative test result in a person who has the disease or condition being tested. Contrast with false-positive.

FALSE-POSITIVE: a positive test result in a person who does not have the disease or condition being tested. Contrast with false-negative.

FASCICULATION: an involuntary muscle contraction.

FAST TRACK: a designation by the Food and Drug Administration to help facilitate the development and to expedite the review process for an experimental drug that has the potential to address an unmet medical need for a serious or life-threatening condition.

FATIGUE: unusual, prolonged, or excessive tiredness.

FAT-SOLUBLE: capable of being dissolved in fat. Contrast water-soluble.

FATTY ACID: an organic molecule made up of a hydrocarbon chain and a carboxylic acid group. Fatty acids may be saturated, monounsaturated, or polyunsaturated.

FDA: see Food and Drug Administration.

FEBRILE: having a fever or increased body temperature.

FECAL-ORAL ROUTE: a route of transmission of infectious organisms which involves the transfer of fecal matter to the mouth—for example, by ingesting contaminated food or water, oral/anal sex.

FECES (adjective FECAL): excrement; excreted waste matter.

FELLATIO: oral sex on a man; contact between the mouth and the penis.

FEMALE CONDOM: see condom.

FIBROMYALGIA (FIBROMYOSITIS): a condition characterized by pain throughout the body, often accompanied by fatigue.

FRIBROMYOSITIS: see fibromyalgia.

FIBROSIS (adjective FIBROTIC): liver damage in which fibrous tissue develops and replaces normal cells.

FIBRINOGEN: a factor produced by the liver that is necessary for proper blood clotting.

FIBROSCAN:  also called transient elastography is a technique that is used to assess the stiffness of the liver, i.e., the degree of the liver damage or scarring.

FILGRASTIM: see granulocyte colony-stimulating factor.

FINE-NEEDLE ASPIRATION BIOPSY: a type of liver biopsy in which a tissue sample is withdrawn using a very fine needle.

FLARE (FLARE-UP): a sudden, acute worsening of disease symptoms.

FLATULENCE: excessive intestinal gas.

FLAVIVIRUS: a group of viruses, several of which cause diseases in humans. HCV is related to flaviviruses, and some taxonomists consider the Hepacivirus genus to be part of the Flaviviridae family.

FLUMADINE: see rimantadine.

FOLIC ACID (FOLATE): a vitamin necessary for red blood cell production and proper neurological function; folic acid also helps prevents neural tube defects in fetuses.

FOOD AND DRUG ADMINISTRATION (FDA): the U.S. federal agency responsible for regulating the development, use, and safety of drugs, medical devices, cosmetics, and related products. The FDA approves new experimental drugs based on the results of clinical trials.

FREE RADICAL: a molecule that contains an unpaired electron. Free radicals are a byproduct of normal metabolism. They are highly reactive and bind with other molecules. The "theft" of electrons by free radicals can disrupt normal cellular processes and cause cellular damage (oxidative stress). See also antioxidant.

FULMINANT: an unusually severe or aggressive form of a disease.

FULMINANT HEPATITIS: a severe, life-threatening form of hepatitis.



G
GALL BLADDER: an organ beneath the liver where bile is stored.

GAMMA GLOBULIN: a preparation of antibodies injected to prevent or treat infection. Gamma globulin is used as post-exposure prevention for hepatitis A and hepatitis B.

GAMMA-GLUTAMYL TRANSPEPTIDASE (GGT): a liver enzyme. Elevated GGT levels may indicate bile obstruction and liver damage. A normal GGT level is 30 to 60 IU/L.

GAN CAO: see licorice root.

GASTROENTERITIS: inflammation of the stomach and intestines.

GASTROENTEROLOGY (also GASTROENTEROLOGIST): the medical specialty that deals with the digestive system; a gastroenterologist treats digestive diseases.

GASTROINTESTINAL: having to do with the digestive system, especially the stomach and intestines.

GASTROINTESTINAL TRACT: the digestive tube consisting of the mouth, esophagus, stomach, small intestine, large intestine, and anus.

GB VIRUS C (GBV-C): see hepatitis G virus.

G-CSF: see granulocyte colony-stimulating factor.

GENE: (adjective GENETIC): the basic unit of heredity. Genes contain hereditary information encoded in the form of DNA (or RNA in some viruses). In animal and plant cells, genes are located on the chromosome in a cell's nucleus.

GENE THERAPY: an approach to preventing or treating disease by replacing, removing, or introducing genes, or otherwise manipulating genetic material.

GENERIC DRUG: a drug that is not protected by a patent and may be produced by any manufacturer.

GENERIC NAME: a common name used to identify a drug, as opposed to a brand name used by a particular company for marketing (e.g., pegylated interferon is the generic name of the drug marketed under the brand names Peg-Intron and Pegasys).

GENETIC ENGINEERING: manipulation of an organism's genetic material to modify the proteins it produces.

GENETIC MATERIAL: deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), the molecules that carry hereditary information.

GENOME: the complete genetic code or "blueprint" of an organism.

GENOTYPE: the genetic makeup of an organism. HCV has seven major genotypes (designated by the numbers 1 through 7). In the U.S. genotype 1a/b is most prevalent. See also quasispecies.

GI: see gastrointestinal.

GLOBULIN: see immunoglobulin.

GLOMERULUS (plural GLOMERULI): a small capillary bed in the kidney where blood filtration takes place.

GLOMERULONEPHRITIS: an inflammatory disorder of the glomeruli, often due to the build-up of cryoglobulins.

GLUCONEOGENESIS: the conversion of glycogen to glucose in the liver.

GLUCOSE (BLOOD SUGAR): a form of sugar that is the body's primary fuel. The liver stores glucose after meals and releases it again as needed. Abnormally low or high levels of glucose in the blood may indicate a metabolic disturbance (e.g., diabetes).

GLUCOSE-6-PHOSPHATE DEHYDROGENASE (G6PD): a human red blood cell enzyme. G6PD deficiency can cause severe anemia.

GLUCOSIDASE INHIBITORS: Inhibitors of endoplasmic reticulum (ER), α-glucosidase has been shown to inhibit viral replication and secretion.

GLUTATHIONE: a natural antioxidant found in the body.

GLYCINE: an amino acid; one of the building blocks of glutathione.

GLYCOGEN: a carbohydrate stored in body tissues. The liver converts glucose from food into glycogen and stores it for later use. When needed, the liver converts glycogen back into glucose.

GLYCYRRHIZIN: see licorice root.

GM-CSF: see granulocyte macrophage colony-stimulating factor.

GRAFT: a transplanted organ or tissue.

GRANULOCYTE: a type of immune system white blood cell (e.g., neutrophil, basophil, eosinophil) that releases toxic chemicals to kill invading microorganisms and mediate allergic reactions.

GRANULOCYTE COLONY-STIMULATING FACTOR (G-CSF): a cytokine that stimulates the production of granulocytes. Genetically engineered G-CSF (filgrastim; brand name Neupogen) is used to treat neutropenia.

GRANULOCYTE MACROPHAGE COLONY-STIMULATING FACTOR (GM-CSF): a cytokine that stimulates growth of granulocytes and macrophages, two types of white blood cell. Genetically engineered GM-CSF (sargramostim; brand names Leukine, Prokine) is used to treat neutropenia.

GRANULOCYTOPENIA: an abnormally low number of granulocytes in the circulating blood, which may lead to an increased risk of bacterial infection. In practice, the term is used to refer to neutropenia.



H
HALF-LIFE: the time required for half of the original amount of a drug to be eliminated from the body, or for a drug to decrease to half its original concentration in the blood.

HAS: see hepatic arterial stenosis.

HAT: see hepatic arterial thrombosis.

HBcAb: Hepatitis B core antibody is produced by the body and indicates that someone has been or is currently infected with hepatitis B.

HBeAb: Hepatitis B “e” antibody is produced by the body and it is an indication that HBV medications or the body is naturally fighting off the virus. Typically people who have the ‘e’ antibody have low HBV DNA (viral load) levels.

HBsAb: Hepatitis B surface antibody is an antibody produced by the body that indicates a person is protected from becoming infected with hepatitis B.

HBeAg: Hepatitis “e” antigen is a protein of the virus and indicates that the virus is actively replicating in the liver and that a person’s blood and bodily fluids are highly infectious.

HBeAg SEROCONVERSION: A marker used to indicate successful treatment of chronic HBV with the loss of HBeAg (“e” antigen) and the development of the HBeAb (“e” antibody).

HBIG: Hepatitis B immune globulin provides short-term protection for people exposed to hepatitis B. It is also given to infants born to HBV-infected mothers along with the infant vaccine to reduce the risk of chronic infection.

HBsAg: Hepatitis B surface antigen is a protein of the virus that is the first to appear after infection. Continued presence of HBsAg for 6 months indicates chronic infection.

HBV DNA: Hepatitis B deoxyribonucleic acid is the type and name of the virus. HBV DNA or viral loads are measured in international units or copies.

HBV RESISTANCE: Development of HBV mutations during HBV drug treatment that allows HBV to replicate and evade the effects of the HBV medications.

HCC: see hepatocellular carcinoma.

HCT: see hematocrit.

HCV RNA: the genetic material of the hepatitis C virus. A detectable level of HCV RNA on a viral load test indicates that HCV is actively replicating.

HELICASE INHIBITOR: a drug that inhibits the action of a virus' helicase enzyme, thus preventing the viral genetic material from unwinding, and interfering with viral replication.

HEMATOCRIT (HCT): the percentage of red blood cells in a given amount of whole blood; the hematocrit reflects the oxygen-carrying capacity of the blood. A normal hematocrit is 40 to 54% for adult men and 37 to 47% for adult women.

HEMATOLOGICAL: having to do with the blood.

HEMATOPOIESIS: the production of blood cells in the bone marrow. Hematopoietic stem cells give rise to all types of red and white blood cells.

HEME: the iron-based pigment in red blood cells, a component of hemoglobin that is released when red blood cells are broken down.

HEMOCHROMATOSIS: iron overload disease; a disease in which iron is not properly metabolized and builds up in tissues throughout the body, especially in the liver.

HEMODIALYSIS: is a process in which a machine filters toxins and waste products from the blood; it is used when the kidneys are no longer able to filter the blood.

HEMOGLOBIN (Hgb): the red, iron-based pigment in red blood cells that enables them to transport oxygen. Also refers to a test of the amount of hemoglobin in red blood cells.

HEMOLYSIS: the breakdown or destruction of red blood cells.

HEMOLYTIC ANEMIA: a low red blood cell count due to excessive cell destruction.

HEMOPHILIA: a hereditary disease in which a person does not produce sufficient blood clotting factors and is prone to prolonged bleeding.

HEMORRHAGE: bleeding.
HEPACIVIRUS: a genus of viruses that includes HCV.

HEPATIC: having to do with the liver; also, an herbal remedy used to treat liver conditions.

HEPATIC ARTERIAL STENOSIS (HAS): narrowing of the hepatic artery.

HEPATIC ARTERIAL THROMBOSIS (HAT): the formation of clots in the hepatic artery.

HEPATIC ARTERY: the blood vessel that delivers oxygen-rich blood to the liver.

HEPATIC COMA: loss of consciousness due to advanced liver disease. When the liver is damaged, it cannot remove toxins from the body; these toxins build up in the bloodstream causing brain damage and other symptoms. Hepatic coma is an indication of advanced liver failure.

HEPATIC ENCEPHALOPATHY: impaired brain function due to advanced liver damage; this occurs when the damaged liver can no longer effectively filter toxins from the bloodstream.

HEPATIC PANEL: see liver function tests.

HEPATIC RESECTION: surgical removal of part of the liver; may be done to treat liver cancer.

HEPATIC VEIN: the blood vessel that carries filtered blood from the liver to the heart.

HEPATITIS: inflammation of the liver. Hepatitis may have various causes, including viruses, toxins, and heavy alcohol consumption.

HEPATITIS A (INFECTIOUS HEPATITIS): a viral disease of the liver that is primarily transmitted by the fecal-oral route. Symptoms may include fever, fatigue, nausea, and jaundice. Hepatitis A typically resolves on its own and does not become chronic. There is no standard treatment for hepatitis A, but an effective vaccine is available.

HEPATITIS A VIRUS (HAV): the virus that causes hepatitis A.

HEPATITIS B (SERUM HEPATITIS): a viral disease of the liver. Hepatitis B is a blood-borne disease, but may also be transmitted sexually or vertically from mother to child. Symptoms may include fever, fatigue, abdominal pain, jaundice, and elevated liver enzymes. Hepatitis B becomes chronic in about 5 to 10% of infected adults. Standard treatments for hepatitis B are interferon and lamivudine; an effective vaccine is available.

HEPATITIS B IMMUNOGLOBULIN (HBIG): a preparation of antibodies administered as postexposure prophylaxis to prevent illness in people exposed to the hepatitis B virus.

HEPATITIS B VIRUS (HBV): the virus that causes hepatitis B.

HEPATITIS C (formerly NON-A / NON-B HEPATITIS): a viral disease of the liver. Hepatitis C is a blood-borne disease; in rare cases it may be transmitted sexually or vertically from mother to child. Symptoms may include fever, fatigue, abdominal pain, jaundice, and elevated liver enzymes. Chronic hepatitis C can lead to long-term liver damage. Standard treatment for hepatitis C is a combination of interferon (standard or pegylated) plus ribavirin; there is currently no vaccine.

HEPATITIS C VIRUS (HCV): the virus that causes hepatitis C.

HEPATITIS D (DELTA HEPATITIS): a viral disease of the liver. Hepatitis D is caused by a blood-borne virus that only causes disease in people already infected with hepatitis B.

HEPATITIS D VIRUS (HDV): the virus that causes hepatitis D.

HEPATITIS E (ENTERIC HEPATITIS): a viral disease of the liver. Hepatitis E is spread through the fecal-oral route. The disease is rare in the U.S., but common in Africa and Asia. It is usually mild, but may be severe and possibly fatal in pregnant women.

HEPATITIS E VIRUS (HEV): the virus that causes hepatitis E.

HEPATITIS G VIRUS (HGV, GB VIRUS C, GBV-C): a blood-borne virus that appears to be related to hepatitis C. It is not known to cause disease.

HEPATOCELLULAR CARCINOMA (HCC): a type of primary liver cancer seen in some people with long-term liver damage due to chronic hepatitis C or hepatitis B.

HEPATOCELLULAR NECROSIS:  concerning localized liver cell tissue death.

HEPATOCYTE: a liver cell.

HEPATOLOGY (also HEPATOLOGIST): the medical specialty that deals with the liver; a hepatologist treats liver disease.

HEPATOMEGALY: enlargement of the liver.

HEPATORENAL SYNDROME: pertaining to the kidney failure in the presence of liver disease.

HEPATOTOXICITY (adjective HEPATOTOXIC): toxic or poisonous to the liver.

HERBALISM (HERBAL THERAPY): the medicinal or therapeutic use of plants or plant products.

HERPES: a common viral infection that can cause fever blisters, genital sores, and shingles.

HGB: see hemoglobin.

HISTAMINE: a cellular compound that is released in response to an allergen and causes the symptoms of allergic reactions.

HISTOLOGY (adjective HISTOLOGICAL): the study or examination of body tissues. In people with HCV, histological improvement refers to improved liver tissue health, including decreased inflammation and reduced fibrosis or cirrhosis.

HISTOLOGICAL RESPONSE: an improvement in liver tissue condition (e.g., reduced inflammation) in response to treatment.

HIV: see human immunodeficiency virus.

HIV DISEASE: infection with the human immunodeficiency virus, which attacks the body's immune system. AIDS is the late, symptomatic stage of HIV disease.

HODGKIN’S DISEASE: tumor or cancer of the lymphatic system.

HOMEOPATHY: an alternative healing system based on the theory that "like cures like." Homeopathic therapy uses extremely diluted doses of substances that normally cause the types of symptoms being treated.

HOMEOSTASIS: the state of equilibrium of the body to maintain a stable internal environment.

HORMONE: a chemical messenger (e.g., adrenaline, testosterone) involved in the regulation and coordination of bodily or cellular functions. Hormones may act locally or be secreted into the bloodstream.

HORMONE REPLACEMENT THERAPY (HRT): the administration of hormones to replace those that the body is unable to produce; typically refers to estrogen replacement therapy in postmenopausal women.

HOST CELL: a cell infected with a virus or other microorganism.

HUMAN IMMUNODEFICIENCY VIRUS (HIV): a slow-acting retrovirus associated with AIDS. HIV is transmitted through blood-to-blood contact, sexual activity, or from mother to child.

HUMAN LEUKOCYTE ANTIGEN (HLA): a genetic marker of "self" which prevents the immune system from attacking the body's own tissues.

HYPERBILIRUBINEMIA: an excess level of bilirubin in the blood, characterized by jaundice, pale-colored stools, and dark urine.

HYPERCHOLESTEREMIA: a high level of cholesterol in the blood.

HYPERGLOBULINEMIA: an abnormally high level of immunoglobulins (antibodies) in the blood.

HYPERGLYCEMIA: high blood sugar.

HYPERTENSION: high blood pressure.

HYPERTHYROIDISM: increased thyroid gland activity and thyroid hormone overproduction

HYPERTROPHIC CARDIOMYOPATHY (HCM): a disease of the heart where enlargement and thickening develops in one part of the heart.

HYPOALBUMINEMIA: a low level of the blood protein albumin.

HYPOTHESIS: an assumption or theory used to guide a scientific investigation.

HYPOTHYROIDISM: decreased thyroid gland activity and reduced thyroid hormone production.



I
IBUPROFEN: a nonsteroidal anti-inflammatory drug used to relieve pain and reduce fever. Advil, Aleve, and Motrin are common brand names.

ICTERUS: see jaundice.

IDIOPATHIC: a term used to describe a disease or condition of unknown cause or origin.

IDU: see injection drug user.

IFN: see interferon.

IG: immunoglobulin; see antibody.
IL28B: see interleukin 28B

IMMUNE CLEARANCE: A phase of chronic HBV that is marked by increased levels of ALT and HBV DNA (viral load). During this phase there is more damage occurring in the liver.

IMMUNE GLOBULIN: see antibody.

IMMUNE RESPONSE: the activity of the immune system, for example against an outside invader (e.g., bacteria, virus), cancerous cells, or the body's own tissues (autoimmune response).

IMMUNE SYSTEM: the body's defense system that protects against foreign invaders (e.g., bacteria, viruses). Some immune defenses are nonspecific (e.g., phagocytosis), while others are directed against specific invaders (e.g., antibody production). Organs of the immune system include the lymph nodes, spleen, thymus, and tonsils.

IMMUNE TOLERANT: A phase of chronic HBV when HBV DNA levels are high, but ALT levels are low. This indicates that there is little liver damage occurring.

IMMUNITY: resistance to disease; the body's ability to recognize and defend against outside invaders and cancerous cells. Immunity may be either natural or acquired (for example, artificially induced through a vaccine).

IMMUNIZATION: the process by which a person is protected against illness caused by a pathogen (e.g., bacteria, virus). Active immunization (vaccination) involves exposing a person to antigens to prompt the body to mount an immune response (e.g., production of antibodies). Passive immunization involves the injection of an antibody preparation (e.g., gamma globulin).

IMMUNOCOMPETENT: capable of mounting an immune response.

IMMUNOCOMPROMISE: see immunodeficiency.

IMMUNODEFICIENCY: inability of the immune system to work properly, resulting in increased susceptibility to disease.

IMMUNOGLOBULIN: see antibody.

IMMUNOMODULATOR: an agent that influences the body's immune response.

IMMUNOSUPPRESSION: see immunodeficiency.

IMMUNOSUPPRESSIVE: a drug or other agent that decreases immune system function.

IMMUNOTHERAPY (IMMUNE-BASED THERAPY): a therapy that attempts to modify or enhance the immune response or reconstitute a damaged immune system.

IMPDH INHIBITOR: see inosine monophosphate dehyrogenase inhibitor.

INACTIVE CARRIER: A phase of chronic HBV that is marked by low HBV DNA, and ALT levels indicating less damage occurring in the liver.

INCIVEK (generic name telaprevir): an HCV protease inhibitor (taken in combination with pegylated interferon plus ribavirin) previously used to treat hepatitis C.

INCIDENCE (also INCIDENCE RATE): the number of new cases of a disease or condition in a specific population during a given period of time. The incidence rate is determined by dividing the number of new cases by the total population. Contrast with prevalence.

INCLUSION CRITERIA: conditions that a person must meet in order to be eligible for a clinical trial. Contrast with exclusion criteria.

INCUBATION PERIOD: the period of time between initial exposure to an infectious microorganism and the development of disease symptoms.

IND: acronym for Investigational New Drug.

INDUCTION THERAPY: the initiation phase of a particular treatment. Typically induction therapy uses higher or more frequent doses of a drug. Contrast with maintenance therapy.

INFECTION: a condition in which the body is invaded by an infectious organism (e.g., bacteria, virus, fungus).

INFECTIOUS: a disease or condition that can be transmitted from one person to another.

INFECTIOUS HEPATITIS: see hepatitis A.

INFERGEN: brand name of interferon alfacon 1 consensus interferon.

INFLAMMATION: the body's response to tissue injury or infection, typically characterized by redness, swelling, heat, and pain.

INFORMED CONSENT: a mechanism designed to protect subjects in clinical trials. Before entering a trial, participants must sign a form stating that they have been given and understand important information about the trial (including possible risks and benefits) and voluntarily agree to take part.

INFUSION: direct injection (e.g., of a drug, nutrients) into the bloodstream.

INHIBITOR: an agent that inhibits or blocks an activity.

INJECTION DRUG USER (IDU): a person who uses an illegal drug (e.g., heroin, cocaine) administered with a needle and syringe. The terms intravenous drug user (IVDU) and people who inject drugs (PWID) are also sometimes used.

INOSINE MONOPHOSPHATE DEHYDROGENASE (IMPDH) INHIBITOR: an agent (e.g., ribavirin) that interferes with the synthesis and storage of guanine, thus inhibiting viral replication.

INSOMNIA: inability to sleep.

INSTITUTIONAL REVIEW BOARD: (IRB): a multidisciplinary group that reviews and ensures the ethical conduct of clinical trials that include human participants.

INSULIN: a peptide hormone produced in the pancreas that enables cells to use glucose. Lack of or insensitivity to insulin results in diabetes.

INSULIN RESISTANCE: a condition in which the body's tissues cannot properly use insulin, leading to blood sugar imbalances.

INTENT-TO-TREAT ANALYSIS: a method of analyzing the results of a clinical trial in which all participants who were originally assigned to an arm are analyzed, including those who dropped out due to treatment failure or side effects. Contrast with as-treated analysis.

INTERFERON (IFN): a cytokine (messenger protein) that plays a role in immune response. The three major classes of interferon are alpha, beta, and gamma.

INTERFERON-ALPHA: a naturally occurring protein produced by the immune system that interferes with viral replication. Interferon-alpha (brand names include Intron-A, Roferon-A).

INTERLEUKIN (IL): a cytokine (chemical messenger), secreted by immune system blood cells, that regulates a range of immune functions.

INTERLEUKIN 28B (IL28B):  a variation of interleukin that directs an immune response to the hepatitis C virus.  IL28B is categorized into genotypes CC, TT, and C/T.  IL28B CC genotype produces that strongest immune response against hepatitis C.

INTERNATIONAL UNIT (IU): a standard unit of measurement.

INTERNAL RIBOSOME ENTRY SITE INHIBITOR: an agent that interferes with the translation of viral genetic material and thus inhibits viral reproduction.

INTOLERANCE: inability of the body to tolerate a drug, resulting in adverse side effects.

INTRACELLULAR: within a cell.

INTRAVENOUS (IV): injected directly into a vein.

INTRAVENOUS IMMUNOGLOBULIN (IVIG): an antibody preparation administered intravenously to treat illness in a person whose own immune system does not produce sufficient antibodies.

INTRON-A: brand name of interferon-alpha-2b.

IN UTERO: in the uterus; refers to events that occur in the womb before birth.

INVESTIGATIONAL NEW DRUG (IND): an FDA classification for experimental drugs that are undergoing clinical trials to assess their safety and effectiveness prior to marketing approval.

INVESTIGATOR: a clinical researcher who is involved with a clinical trial protocol and its implementation. The Principal Investigator is ultimately responsible for the conduct of the trial.

IN VITRO: Latin for "in glass"; refers to studies done in a test tube or culture medium in the laboratory.

IN VIVO: Latin for "in a living organism"; refers to studies done using human or animal subjects.

IRES INHIBITOR: see internal ribosome entry site inhibitor.

IRON: an important trace element needed for the production of hemoglobin in red blood cells. High levels of iron can be toxic to the liver.

IRON-DEFICIENCY ANEMIA: the most common type of anemia, caused by a lack of iron.

ISCHEMIA: reduced blood supply to bodily tissues.

ISLET CELL: a cell in the Islets of Langerhans in the pancreas that produces insulin.

IU: see international unit.

IV: see intravenous.

IVDU: see injection drug user.

IVIG: see intravenous immunoglobulin



J
JAUNDICE: (icterus, icteric) yellowing of the skin and whites of the eyes due to high bilirubin levels in the blood. Jaundice is often a sign of liver damage or gallbladder disease.



K
KAYSER-FLEISCHER RINGS: see Wilson’s disease.

KETONE: a byproduct of fat metabolism. When the body does not have enough glucose, the liver converts fatty acids into ketones, which are used as fuel by the muscles.

KIDNEY (adjective RENAL): one of two bean-shaped organs located in the lower back part of the abdominal cavity. The kidneys filter waste material from the blood and excrete urine.

KIDNEY STONE (NEPHROLITHIASIS): an accumulation of substances (e.g., drug crystals, minerals) in the kidneys, leading to blockage and pain.

KUPFFER CELL: a type of macrophage that resides in the liver and ingests bacteria absorbed from the intestines.



L
LACTATION: production of breast milk.

LAMIVUDINE (Brand name EPIVIR-HBV): A nucleoside analogue medicine used to treat chronic hepatitis B and HIV. Lamivudine is not recommended as a first line of HBV treatment because of the high rate of drug resistance.

LAPAROSCOPIC LIVER BIOPSY: a type of liver biopsy using a laparoscope.

LAPAROSCOPY: a procedure in which a lighted instrument is inserted through an abdominal incision for the purpose of diagnosis, biopsy, or surgery.

LATENCY: (adjective LATENT): the state in which a disease-causing organism is present in the body, but not actively replicating or causing illness.

LAXATIVE: an agent that promotes bowel evacuation (defecation).

LECITHIN: a fatty compound required for proper metabolism.

LEDIPASVIR: an HCV NS5A inhibitor (used in combination with sofosbuvir as part of brand name HARVONI) used to treat hepatitis C.

LESION: a tissue injury or wound.

LEUKINE: see granulocyte-macrophage colony-stimulating factor.

LEUKOCYTE: an immune system white blood cell (e.g., T-cell, B-cell, neutrophil).

LICHEN PLANUS: an inflammatory disease of the skin and mucous membranes characterized by red or purple bumps or blotches. The cause of lichen planus is not known, but it appears to be an autoimmune condition.

LICORICE ROOT (GLYCYRRHIZA GLABRA, GLYCYRRHIZIN, GAN CAO): an herbal remedy traditionally used to treat diseases of the liver and bronchial conditions. Glycyrrhizin is an active component of licorice root.

LIPID: a fat.

LIPODYSTROPHY: a syndrome that involves abnormal lipid metabolism and redistribution of body fat.

LIPOGENESIS: production of lipids (fats).

LIVER: a large organ on the upper right side of the abdomen that plays an important role in the metabolism of sugars and fats, synthesizes several proteins, and filters toxins from the blood.

LIVER BIOPSY: a medical procedure that removes a piece of liver tissue which is then examined under a microscope for inflammation and damage.

LIVER CANCER: malignant proliferation of cells in the liver. The most common type of liver cancer in people with chronic hepatitis is hepatocellular carcinoma.

LIVER CELL: see hepatocyte.

LIVER ENZYME: see aminotransferase.

LIVER FUNCTION TESTS (HEPATIC PANEL): a group of blood tests that measure levels of liver enzymes, proteins, and various other substances. Liver function tests are used to help diagnose liver disease, assess the degree of liver damage and determine how well treatment is working.

LIVING DONOR: a person who donates an organ or part of an organ while alive to another person.

LOBE: one of the four anatomical divisions of the liver; lobes are further divided into lobules.

LOBULE OF LIVER: a structural unit consisting of hepatic (liver) cells shaped like a hexagon with six portal triads surrounding a central vein.

LOG: a measure based on the logarithmic scale that refers to quantities in factor of ten. A log change is an exponential, or 10-fold, increase or decrease (e.g., a change from 10 to 100 is a 1-log increase; a change from 1,000,000 to 10,000 is a 2-log decrease). Viral load is sometimes expressed in logs.

LUPUS: see systemic lupus erythematosus.

LYMPH NODE (LYMPH GLAND): a small, bean-sized organ located throughout the body, with concentrations in the neck, groin, and armpits. Lymph nodes filter out antigens and are the site of immune cell activation.

LYMPHATIC SYSTEM: a network of organs and vessels that help maintain the fluid environment of the body and coordinate immune responses. The lymphoid organs include the lymph nodes, spleen, thymus, tonsils, and adenoids.

LYMPHOCYTE: a type of white blood cell (e.g., T-cell, B-cell, natural killer cell) that plays a role in the body's immune defense.

LYMPHOCYTOPENIA: a deficiency of lymphocytes.



M
MACROPHAGE: a large scavenger white blood cell that ingests and processes foreign invaders and cellular debris. Specialized macrophages protect the skin, lungs (alveolar macrophages), brain (microglia), liver (Kupffer cells), and other tissues.

MAGNETIC RESONANCE IMAGING (MRI): a sensitive, non-invasive method for viewing soft tissues of the body using a magnetic field.

MAINTENANCE THERAPY: therapy that follows successful initial treatment of an illness; generally maintenance therapy continues for a long period of time (possibly for life) to prevent disease recurrence. Contrast with induction therapy.

MAJOR HISTOCOMPATIBILITY COMPLEX (MHC): a group of genes that controls the expression of cell surface protein markers (also known as human leukocyte antigen, or HLA, markers) that allow immune cells to recognize the body's own cells (that is, to distinguish "self" from "non-self").

MALAISE: a generalized feeling of illness and discomfort; a flu-like feeling.

MALIGNANCY: a cancer, neoplasm, or tumor that grows in an uncontrolled manner, and may invade nearby tissue and metastasize, or spread, to other areas of the body.

MALIGNANT: a condition that is severe, harmful, or resistant to treatment. Contrast with benign.

MALNUTRITION: lack of the minimum amount of nutrients (proteins, carbohydrates, lipids, vitamins, minerals, etc.) necessary for good health. Malnutrition may result from poor diet, lack of appetite, or inadequate absorption of nutrients from the gastrointestinal tract.

MAXIMINE: see histamine dihydrochloride.

MEAN: (AVERAGE): a statistical measurement of the central tendency, or average, of a set of values. For example, in the series of values "1, 1, 3, 5, 6, 8, 8, 10, 21," the mean is 7 (determined by adding up all the values and dividing by the number of values). Contrast with median.

MEDIAN: the number within a series that is preceded and followed by an equal number of values. For example, in the series of values "1, 1, 3, 5, 6, 8, 8, 10, 21," the median is 6 (there are four values lower and four values higher). Contrast with mean.

MEDICAID: in the United States, a program that is funded by federal and state governments that pays for medical care for those who can’t afford it.

MEDICARE: in the United States, a program that pays for certain health care expenses for people 65 and older.

MEDITATION: a technique for relaxation and clearing and focusing the mind.

MEGAKARYOCYTE: a large precursor blood cell that gives rise to platelets.

MELD: an acronym for Model End Stage Liver Disease. A severity score or calculation used for adults with liver disease to rank candidates for liver transplantation.

MEMBRANE: a thin sheet or layer of tissue that serves as a semi-permeable covering.

MEMBRANOPROFLIFERATIVE GLOMERULONEPHRITIS (MH) is a condition that affects the kidneys that is usually (but not always) associated with cryoglobulinemia. Symptoms include weakness, edema and arterial hypertension. (See also glomerulonephritis)

MEMBRANOUS NEPHROPATHY: a disease of the kidneys where HCV antibodies and viral particles are deposited in the kidneys.

MENOPAUSE: the cessation of menstruation.

MENSTRUATION: a stage of the female reproductive cycle. An ovum (egg) matures and is released every month. Hormones prepare the uterus for possible implantation. If pregnancy does not occur, the uterine lining (blood and tissue) is shed and expelled (the menstrual period).

MESSENGER RNA (mRNA): a piece of ribonucleic acid that carries genetic information from DNA to ribosomes in order to synthesize new proteins.

METABOLISM (adjective METABOLIC): the processes of building the body's molecular structures from nutrients (anabolism) and breaking them down for energy (catabolism). Also, the chemical processing or breakdown of food, drugs, and toxins.

METASTASIS (adjective METASTATIC, verb METASTASIZE): a disease (especially cancer) that spreads from one part of the body to another.

METHADONE: an oral opiate-like drug used for pain management and to treat opiate (e.g., heroin) addiction. Methadone maintenance therapy prevents withdrawal symptoms by administering small doses of the drug on a regular basis.

METHIONINE: see s-adenosylmethionine.

MILK THISTLE (SILYBUM MARIANUM, SILYMARIN): the most widely used herbal remedy to treat chronic hepatitis. Silymarin is a combination of active components derived from milk thistle. Studies suggest that milk thistle can reduce hepatitis symptoms and helps prevent liver damage.

MINERAL: an inorganic element that promotes chemical reactions within the body and is necessary for proper cellular metabolism. Essential minerals include calcium, iodine, iron, magnesium, potassium, and zinc.

MISCARRIAGE: a pregnancy that ends prematurely and is not carried to term.

MITOCHONDRION (plural MITOCHONDRIA): a rod-shaped organelle in the cytoplasm of a cell that produces energy.

MHC: see major histocompatibility complex.

MOLECULE: a small unit of matter made up of atoms. A molecule is the smallest unit of a substance that retains its unique characteristics.

MONOCLONAL ANTIBODIES: a preparation consisting of identical antibodies active against a specific pathogen.

MONOCYTE: a large white blood cell that plays a role in immune defense. Monocytes circulate in the bloodstream; when they migrate to the tissues, they mature into macrophages.

MONOGAMY (MONOGAMOUS): having a single spouse; more often used to refer to having a single sexual partner.

MONOTHERAPY: use of a single drug for treatment. Monotherapy for HCV is no longer considered standard treatment. Contrast with combination therapy.

MOOREN CORNEAL ULCERATION: a condition affecting the eyes causing pain, inflammation, tearing and loss of sight.

MORBIDITY: sickness; the state of being affected by disease.

MORTALITY (also MORTALITY RATE): death. The mortality rate is the rate of death in a given population.

MOXA: the herb mugwort.

MOXIBUSTION: in traditional Chinese medicine, the burning of an herb (moxa) to generate heat and stimulate the flow of qi.

MRI: see magnetic resonance imaging.

mRNA: see messenger RNA.

MU: abbreviation for million units.

MUCOUS MEMBRANE (MUCOSA): a moist layer of semi-permeable tissue lining the openings of the body (e.g., the gastrointestinal, respiratory, and genitourinary tracts).

MULTIFOCAL: occurring at more than one site.

MULTIPLE MYELOMA: a form of cancer of the bone marrow that causes anemia, infections, and bleeding.

MULTIVARIATE ANALYSIS: a statistical analysis that takes into account several different factors or variables.

MULTIVITAMIN: a nutritional supplement that contains several different essential vitamins and minerals.

MUTATION (verb MUTATE): a change in the character of a gene that is perpetuated when a cell divides or a virus replicates.

MYALGIA: muscle pain.

MYELIN: a white fatty substance that forms a sheath around the axons of neurons (nerve cells) and provides the insulation necessary for the proper transmission of electrical impulses.

MYELOSUPPRESSION: inhibition of the bone marrow, resulting in decreased blood cell production.

MYELOTOXIC: poisonous to or destructive of the bone marrow.

MYOCARDIAL INFARCTION: blockage of the arteries serving the heart, often leading to angina pectoris and/or heart attack.

MYOPATHY: muscle inflammation, damage, or disease.



N
NAC: see n-acetyl-cysteine.

N-ACETYL-CYSTEINE (NAC): a form of the animo acid cysteine that is available as a nutritional supplement. NAC is used to prevent liver damage due to acetaminophen overdose.

NAIVE: inexperienced. Often used to describe an individual who has never taken a certain drug, or to an undifferentiated immune system cell.

NARCOTIC: see opiate.

NATURAL HISTORY STUDY: a study of the natural development of a disease over time.

NATIONAL INSTITUTES OF HEALTH: (NIH): a large biomedical research organization that is part of the U.S. Public Health Service. The NIH includes several institutes, centers, and divisions. The National Institute of Allergy and Infectious Diseases (NIAID) and the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) conduct research on viral hepatitis.

NATURAL KILLER (NK) CELL: a type of white blood cell that attacks and kills tumor cells and cells infected with microorganisms.

NATUROPATHY: a system of natural healing based on the philosophy that the body has the ability to cure itself.

NAUSEA: stomach distress characterized by an aversion to food and an urge to vomit.

NDA: see new drug application.

NECROSIS: cell or tissue death.

NECROINFLAMMATION: tissue inflammation and death.

NEONATE (adjective NEONATAL): a newborn, especially within the first days or weeks after birth.

NEOPLASM (NEOPLASIA): a tumor or growth; tissue that develops abnormally or cells that proliferate more rapidly than normal. A benign neoplasm (e.g., a wart) is localized and does not spread to other tissues; a malignant neoplasm (cancer) can spread to other parts of the body.

NEPHROLITHIASIS: see kidney stone.

NEPHROTOXICITY: the property of being poisonous or harmful to the kidneys.

NEUPOGEN: see granulocyte colony-stimulating factor.

NEURALGIA: nerve pain.

NEUROPATHY (adjective NEUROPATHIC): nerve damage or disease.

NEUTROPENIA: an abnormally low number of neutrophils, resulting in increased susceptibility to infection.

NEUTROPHIL: the most common type of immune system white blood cell. Neutrophils are phagocytes that engulf and destroy invading organisms such as bacteria and fungi.

NEW DRUG APPLICATION (NDA): an application made by a drug manufacturer to the FDA to request marketing approval for a new drug.

NIACIN: see vitamin B.

NIAID: National Institute of Allergy and Infectious Diseases. See National Institutes of Health.

NIDDK: National Institute of Diabetes and Digestive and Kidney Diseases. See National Institutes of Health.

NIH: see National Institutes of Health.

NK CELL: see natural killer cell.

NON-A/NON-B HEPATITIS: see hepatitis C.

NON-HODGKIN’S LYMPHOMA (NHL): cancer of lymphoid tissues.

NONINVASIVE: a device or procedure that does not require puncturing the skin.

NON-NUCLEOSIDE REVERSE TRANSCRIPTASE INHIBITOR (NNRTI): an antiviral drug that suppresses viral replication by interfering with the action of the reverse transcriptase enzyme.

NONOXYNOL-9: a chemical formerly used as a spermicide and microbicide. Studies have shown that nonoxynol-9 causes tissue damage and may increase the risk of STD transmission.

NONRESPONDER: person who does not show improvement while undergoing treatment. In HCV, a nonresponder does not achieve normal ALT levels or an undetectable viral load.

NONSTEROIDAL ANTI-INFLAMMATORY DRUG (NSAID): a drug (e.g., aspirin, acetaminophen, ibuprofen) that relieves pain and reduces inflammation by blocking the body's production of prostaglandins.

NNRTI: see non-nucleoside reverse transcriptase inhibitor.

NS5A INHIBITOR: an agent that inhibits viral replication of the hepatitis C virus’ NS5a enzyme.

NRTI: see nucleoside reverse transcriptase inhibitor.

NSAID: see nonsteroidal anti-inflammatory drug.

NUCLEOSIDE ANALOG: see nucleoside reverse transcriptase inhibitor.

NUCLEOSIDE REVERSE TRANSCRIPTASE INHIBITOR (NRTI, NUCLEOSIDE ANALOG): a drug that mimics a nucleoside, one of the building blocks of genetic material (DNA or RNA). NRTIs suppress viral replication by interfering with the action of the reverse transcriptase enzyme, causing premature termination of new chains of genetic material. Ribavirin is an NRTI.

NUCLEOTIDE: a genetic building block.

NULL RESPONDER: a person who does not achieve a 2 log10 drop of HCV RNA by treatment week 12.

NUTRIENT: an agent that promotes proper growth and metabolism.

NUTRITION: the process by which living organisms digest and metabolize food to use for maintenance and growth of tissues.



O
OFF-LABEL: use of an FDA-approved drug for an indication other than that for which it was approved.

OLYSIO: see simeprevir

OMBITASVIR: (formerly ABT-267) is an HCV polymerase inhibitor (Ombitasvir is part of brand name VIEKIRA PAK) that is used to treat hepatitis C.

ONCOGEN: an agent that promotes neoplastic cell growth, or cancer.

ONCOGENESIS: the development and growth of cancer.

ONCOLOGIST: a physician who specializes in the treatment of cancer.

ONCOLOGY: the study and treatment of cancer.

OPEN-LABEL: a drug trial which is not randomized and not blinded; both participants and investigators know what drug is being tested and what dosages are being used.

OPIATE (NARCOTIC): a class of drugs (e.g., heroin, codeine, methadone) that are derived from the opium poppy or produced synthetically and have opium-like effects. Opiate drugs relieve pain, dull the senses, and induce sleep.

OPPORTUNISTIC ILLNESS (OPPORTUNISTIC INFECTION, OI): an illness or infection that does not normally occur in a person with a healthy immune system, but affects immunocompromised persons.

ORAL: relating to the mouth; taken by mouth.

ORGANIC FOOD: food that is grown naturally without the use of chemical fertilizers, pesticides, or other artificial intervention.

ORPHAN DRUGS: an FDA category of drugs developed to treat conditions that rarely occur.  The FDA offers financial incentives to offset the predicted lower rate of return on the investment in clinical development.

OSTEOARTHRITIS: degenerative joint disease.

OTC: see over-the-counter.

OVER-THE-COUNTER (OTC): drugs that are available without a prescription.

OXIDATIVE STRESS: increased levels of free radicals in the body, potentially leading to cell damage and death.



P
PALLIATIVE: offering symptomatic relief and comfort care (e.g., alleviation of pain) rather than a cure.

PALLOR: paleness.

PANCREAS: a digestive gland in the abdominal cavity that secretes digestive enzymes.

PANCREATITIS: inflammation of the pancreas.

PANCYTOPENIA: an abnormally low level of all types of blood cells, typically due to bone marrow damage.

PARACENTESIS: a procedure to remove fluid that has accumulated in the abdominal cavity—a condition called ascites.

PARACETOMAL: see acetaminophen

PARENTERAL: nutrients given by injection into a vein, bypassing the gastrointestinal tract.

PARITAPREVIR (ABT-450):  a protease inhibitor. It is boosted with low dose ritonavir (paritaprevir is part of brand name VIEKIRA PAK) and is used to treat hepatitis C.

PATHOGEN (adjective PATHOGENIC): any disease-causing agent, especially a microorganism (bacteria, virus, fungus, parasite).

PATHOGENESIS: the development and progression of a disease.

PATHOLOGY (adjective PATHOLOGIC): the study of disease, including the causes, development, and progression of disease, and how the body is affected.

PCR: see polymerase chain reaction.

PEAK LEVEL: the highest level of drug reached in the body after a dose is taken. Contrast with trough level.

PEER REVIEW: a review of the scientific merit of a clinical trial by independent experts.

PEGASYS: brand name of pegylated interferon-alpha-2a.

PEGINTERFERON: see pegylated interferon.

PEG-INTRON: brand name of pegylated interferon-alpha-2b.

PEGYLATED INTERFERON (PEGINTERFERON): a form of interferon that has a long half-life in the body and can be injected less often (typically once per week). Pegylated interferon (brand names Peg-Intron, Pegasys) appears superior to standard interferon as a treatment for HCV.

PEGYLATION: a process in which polyethylene glycol (PEG) molecules are attached to proteins in order to extend their activity in the body.

PEI: see percutaneous ethanol injection.

PERCUTANEOUS: through the skin.

PERCUTANEOUS ETHANOL INJECTION: a treatment for hepatocellular carcinoma in which ethanol (alcohol) is injected into the tumor.

PERIHEPATITIS: inflammation of the lining of the liver.

PERINATAL: the period around the time of birth.

PERINATAL TRANSMISSION: see vertical transmission.

PERIPHERAL NEUROPATHY: damage to the peripheral nerves, usually involving the feet and hands.

PERITONEUM: the thick membrane that lines the abdominal cavity and covers the visceral organs.

PERITONITIS: inflammation of the peritoneum.

PERNICIOUS ANEMIA: a type of anemia caused by the inability of the intestine to absorb vitamin B12, which is needed to produce red blood cells.

PHAGOCYTE: a scavenger cell that engulfs and destroys invading pathogens (phagocytosis).

PHARMACEUTICAL: having to do with the development and manufacture of drugs, or to a manufactured drug.

PHARMACOKINETICS: the action of drugs in the body, including the processes of absorption, metabolism, distribution to tissues, and elimination.

PHARMACOLOGY: the science of drugs, their sources, and how they work.

PHASE I TRIAL: the first stage of human testing of a new treatment. Phase I trials evaluate drug pharmacokinetics, safety, and toxicity at different dose levels, typically in a small number of healthy volunteers or in those who have the condition or disease.

PHASE II TRIAL: the second stage of the evaluation of a new treatment in humans. Phase II trials evaluate safety and preliminary efficacy in a larger number of participants than Phase I studies.

PHASE III TRIAL: the third stage of human testing of an experimental treatment. Phase III trials are designed to determine the safety and efficacy of a treatment, often by comparing it to an existing standard therapy or a placebo.

PHASE IV TRIAL: post-marketing studies done after a new treatment is approved and offered for sale. These trials provide additional information about safety and efficacy in large numbers of patients under "real world" conditions.

PHLEBOTOMY: withdrawal of blood from a vein.

PHOTOSENSITIVITY: an increased sensitivity to light, which may lead to easy sunburning and other adverse effects.

PHYLLANTHUS: tropical plant species that traditionally have been used to treat liver conditions.

PIGMENT: a substance responsible for the color of bodily tissues.

PLACEBO: an inert, inactive agent (e.g., pill, injection) that has no treatment value.

PLACEBO ARM: the group of participants in a clinical trial that receives an inactive substance (placebo).

PLACEBO-CONTROLLED TRIAL: a clinical trial in which a group receiving an inactive substance or mock therapy (placebo) is compared to a group receiving the experimental treatment.

PLACEBO EFFECT: a change in symptoms or disease progression associated with the treatment process itself, rather than the actual therapeutic value of a treatment.

PLACENTA: the organ that connects the fetus and the mother's uterus and enables the exchange of oxygen, nutrients, and waste products.

PLASMA: the fluid, non-cellular portion of circulating blood. See also serum.

PLASMAPHERESIS: a procedure in which certain components are removed from the blood plasma.

PLATELET: see thrombocyte.

PLATELET COUNT: The number of platelets in the blood. People with advanced liver disease may have reduced platelet counts, resulting in easy bleeding. A normal platelet count is 130,000-400,000/mcl.

PNEUMONITIS: lung inflammation.

PO: taken by mouth.

POLYMERASE CHAIN REACTION (PCR): a highly sensitive test that uses an amplification technique to detect small amounts of genetic material (DNA or RNA) in a blood or tissue sample.

POLYMERASE INHIBITOR: an agent that inhibits viral replication by interfering with the polymerase enzyme.

PORPHYRIA CUTANEA TARDA: a condition in which porphyrins build up in the body leading to symptoms including increased photosensitivity, skin damage, and discoloration.

PORPHYRIN: a metabolic byproduct of hemoglobin production.

PORTAL HYPERTENSION: high blood pressure in the portal vein that carries blood to the liver, caused by the development of fibrous scar tissue (cirrhosis) in the liver.

PORTAL SYSTEM: a series of veins from the small and large intestines, stomach, and spleen that join into the portal vein and are carried into the liver.

PORTAL VEIN: the blood vessel that carries oxygen-poor blood from the intestines to the liver for filtering.

POSTEXPOSURE PREVENTION (POSTEXPOSURE PROPHYLAXIS, PEP): treatment given immediately following exposure to an infectious organism in an attempt to prevent the infection from taking hold in the body.

POST-MARKETING STUDY: see Phase IV trial.

POSTNATAL (POSTPARTUM): the period following birth.

POTASSIUM: an element and electrolyte responsible for the body’s growth and maintenance.

POWER: a statistical term used to describe the ability of a clinical trial to detect a particular result. Generally the power of a study increases as more participants are included or as the trial continues for a longer period of time.

PRANA: in Ayurveda, the body's vital energy.

PRECLINICAL RESEARCH: laboratory and animal studies on an experimental treatment prior to clinical trials in humans.

PRENATAL: the period preceding birth, during which the fetus develops in the uterus.

PREVALENCE (also PREVALENCE RATE): the number of individuals with a condition in a specific population. The prevalence rate is determined by dividing the number of people with the condition by the total population. Contrast with incidence.

PRIMARY CARE PHYSICIAN: a physician who is responsible for the overall long term health maintenance of a patient.

PRINCIPLE INVESTIGATOR: the chief researcher conducting a clinical trial.

PRIOR PARTIAL-RESPONDER: a person who has a 2 log10 drop in HCV RNA by treatment week 12, but who does not become HCV RNA negative by end of treatment. (Example 2 log10 drop: 1,000,000 to ≤ 10,000)

PROCRIT: see erythropoietin.

PRODRUG: a compound that is converted to an active drug within the body.

PROGESTERONE: a female hormone with anti-estrogen effects. Progesterone prepares the uterus for the development of the fertilized ovum and maintains the uterus throughout pregnancy.

PROGNOSIS (adjective PROGNOSTIC): a forecast of the probable course or outcome of a disease.

PROGRESSION: development of a disease over time.

PROKINE: see granulocyte colony-stimulating factor.

PROPHYLAXIS: a measure taken to prevent a disease or condition.

PROSPECTIVE STUDY: a clinical trial in which participants are selected and their progression is followed over time. Contrast with retrospective study.

PROTEASE INHIBITOR: an agent that inhibits viral replication by interfering with the virus' protease enzyme.

PROTEIN: a complex organic compound consisting of a sequence of amino acids folded in a specific configuration. Proteins are major components of living cells and are essential for bodily growth and repair.

PROTHROMBIN: a protein synthesized by the liver that is necessary for proper blood clotting.

PROTHROMBIN TIME (PT): a measure of blood clotting time. People with advanced liver disease may have a slower than normal PT. A normal PT is 10-12 seconds.

PROTOCOL: a written plan for a clinical trial, which typically includes details such as the hypothesis to be tested, who can participate, length of the trial, how the treatment under study will be administered, endpoints, and potential risks and benefits.

PRURITUS (adjective PRURITIC): itchiness.

PSORIASIS: a skin condition characterized by scaling and red patches, due to the overproduction of skin cells.

PSORIATIC ARTHRITIS: a form of rheumatoid arthritis associated with psoriasis.

PSYCHOSIS: a serious mental illness.

PSYCHOSOCIAL: a term used to refer to factors that affect the psychological or social realm. Psychosocial factors (e.g., socioeconomic status, education, family situation) can have an important effect on disease risk and progression and are an essential aspect of a person's well-being.

PSYCHOTHERAPY: treatment of mental problems with non-medical therapies, in particular counseling.

PSYCHOTROPIC: a drug that affects psychological or mental functioning or behavior.

PULMONARY FIBROSIS: the development of fibrous tissue in the lungs.

PT: patient.

PURPURA: see thrombocytopenic purpura.

PURULENT: characterized by the accumulation of pus.

PUS: a thick, greenish-yellow fluid composed of dead white blood cells, killed microorganisms, and other cellular debris.

P-VALUE: a measure of probability that is reported with clinical trial results. The p-value indicates the likelihood the result obtained are due to chance alone. Traditionally, a p-value of less than .05 is considered statistically significant, or not likely due to chance alone. See also confidence interval.

PYRROLIZIDINE ALKALOID: a hepatotoxic component found in plants of the Crotalaria, Senecio, and Heliotropium families.



Q
Q: medical abbreviation for every, often used to specify drug dosing schedules (e.g., q6h means every 6 hours).

QI (CHI): the vital energy believed to be responsible for health and disease in traditional Chinese medicine.

QIGONG: a form of traditional Chinese exercise that promotes the healthy flow of qi.

QUALITY OF LIFE STUDY (QOL): a clinical trial that measures how a condition affects the daily life of a person with a chronic illness.  A clinical trial of an investigational medication may have a quality of life component to find out the effects of the study drug on QOL and if successful treatment improves QOL.

QUALITATIVE: relating to, or expressed in terms of, quality. A qualitative viral load test measures the presence of a virus.

QUANTITATIVE: relating to, or expressed in terms of, quantity. A quantitative viral load test measures the amount of viral genetic material.

QUASISPECIES: individual genetic variants of HCV. Within a single genotype there may be multiple quasispecies.



R
RA: see rheumatoid arthritis.

RADIATION THERAPY (RADIOTHERAPY): the use of radiation to treat disease (especially cancer).

RADIOGRAPHY: the use of X-ray pictures, for example for diagnosis.

RADIOLOGIST: a physician who uses x-rays or other imaging procedures for diagnosis and treatment.

RANDOMIZED TRIAL: a clinical trial arranged to produce a chance distribution of participants into different arms (e.g., experimental treatment, standard treatment, or placebo). Clinical trial participants are usually randomized by computer to prevent potential bias of investigators.  Randomization is done to minimize bias. 

RAPID VIROLOGICAL RESPONSE (RVR): HCV RNA negative at treatment week 4.

RAYNAUD'S PHENOMENON: temporary interruption of blood flow to the extremities (fingers, toes, tip of nose and ears), often associated with exposure to cold temperatures.

RBC: red blood cell. See erythrocyte.

RBV: see ribavirin.

REACTIVATION: the return of a previously latent (inactive) infection to an active, pathogenic state.

REACTIVE ARTHRITIS (REITER'S SYNDROME): an arthritic disorder, often linked to conjunctivitis, that appears to be associated with viral infections.

REBETOL: Schering’s brand of ribavirin. see ribavirin.

REBETRON: a bundled kit for HCV treatment that packages together Intron-A brand interferon and ribavirin.

REBOUND: an increase in viral load following a previous decrease.

RECEPTOR: a specific binding site on a cell's surface or in its interior. When chemical messengers or drugs bind to receptors, various cellular functions are activated or inhibited. Viruses must bind receptors in order to enter cells.

RECOMBINANT: produced by genetic engineering.

RECONSTITUTION: mixing a substance (e.g., Peg-Intron brand pegylated interferon) with water to return it to a usable form.

RECURRENT: returning or occurring repeatedly.

RED BLOOD CELL: see erythrocyte.

RECRUITMENT: the period of time assigned to identify and enroll in a clinical trial.

REFLEXOLOGY: an alternative healing technique that involves putting pressure on various zones of the body.

REFRACTORY: resistant to treatment.

REGENERATION: regrowth.

REGIMEN: a specific treatment protocol, including what drugs are taken and at what dosages.

REIKI: a healing technique in which energy is channeled through the hands of the healer.

REITER'S SYNDROME: see reactive arthritis.

RELAPSE: recurrence of disease symptoms following a period of improvement. In HCV, relapse can refer to an increase in viral load after it has been suppressed.

RELAPSER: a person who becomes HCV RNA negative at end of treatment, but becomes HCV detectable within 24 weeks from the end of treatment (EOT).

RENAL: having to do with the kidneys.

REPLICATION: multiplication or reproduction, specifically used when referring to a virus.

RESECTION: see hepatic resection.

RESISTANCE: the mutation of a microorganism in such a way that it loses its sensitivity to a drug; a resistant organism can function and replicate despite the drug's presence.

RESOLVE: when referring to a condition, to clear up or heal.

RESPONDER-RELAPSER: a person who initially responds well to a treatment, but then experiences a relapse. In chronic HCV infection, this refers to a person who initially has a positive response to treatment (e.g., normal ALT, undetectable HCV RNA), but does not sustain this response once treatment is stopped.

RESPONSE-GUIDED TREATMENT: Response-guided therapy uses HCV RNA testing during treatment to predict response and guide treatment duration for patients with chronic hepatitis C.

RESPONSE TO TREATMENT: see treatment response.

RETINOPATHY: disease of the retina of the eye.

RETROSPECTIVE STUDY: a study based on medical records, looking backward in time at events that happened in the past. Contrast with prospective study.

RETROVIRUS: a class of viruses that have their genetic material in the form of RNA and use the reverse transcriptase enzyme to transcribe their RNA into DNA within the host cell.

RHEUMATOID ARTHRITIS (RA): an autoimmune condition characterized by joint inflammation and destruction of connective tissue; other organs, including the heart, lungs, kidneys, and skin, may also be affected.

RHEUMATOID FACTOR: a type of antibody (IgM) that reacts to abnormal IgG antibodies produced by people with autoimmune conditions such as rheumatoid arthritis.

RHEUMATOLOGY: the study and treatment of conditions of the joints, muscles, bones, and connective tissues.

RIBA: a type of antibody test; RIBA is often used to confirm HCV antibody positivity detected on an ELISA II test.

RIBASPHERE: Kadmon Pharmaceutical’s brand of generic ribavirin; see ribavirin.

RIBAVIRIN (RBV)—brand name REBETOL, COPEGUS, RIBASPHERE, MODERIBA: an antiviral medication approved for use in combination with interferon to treat chronic HCV infection.

RIBONUCLEIC ACID (RNA): a single-stranded nucleic acid that encodes genetic information. The presence of viral RNA in the blood indicates that a virus is actively replicating. Hepatitis C and HIV are examples of RNA viruses.

RNA is made up of sequences of four building blocks: adenine, cytosine, guanine, and uracil. The presence of viral RNA in the blood indicates that a virus is actively replicating.

RIBOSOME: small organelles in the cell where new proteins are built from the RNA "blueprint."

RIBOZYME: an RNA molecule that cleaves (cuts) RNA strands at a specific site. A ribozyme directed against a specific region of the HCV genome is currently under study as a treatment for HCV.

RISK/BENEFIT RATIO: a measurement used to evaluate whether potential benefits outweigh potential risks (e.g., in a clinical trial).

RNA: see ribonucleic acid.

ROFERON-A: brand name of interferon-alpha-2a.

RX: treatment.



S
S-ADENOSYLMETHIONINE (SAM-E, METHIONINE): a natural compound found in cells and available as a nutritional supplement.

SAFER SEX: sexual activities that reduce or eliminate the spread of sexually transmitted diseases, typically by blocking contact with semen and/or vaginal fluid.

SALVAGE THERAPY: emergency treatment with experimental drugs for an illness that does not respond to standard therapy.

SAM-E: see s-adenosylmethionine.

SAMPLE SIZE: the number of participants in a clinical trial.

SARCOIDOSIS: an autoimmune condition characterized by granulomas (small nodules of cells); the condition may affect the lungs, skin, eyes, liver, and other organs.

SARGRAMOSTIM: see granulocyte colony-stimulating factor.

SCHISANDRA (WU WEI ZI): a plant used in traditional Chinese and Russian medicine to treat liver conditions.

SCLERODERMA: an autoimmune condition characterized by hardened skin and connective tissue.

SEIZURE: a burst of abnormal electrical activity in the brain.

SELECTIVE SEROTONIN REUPTAKE INHIBITOR (SSRI): a psychotropic drug (e.g., Prozac, Zoloft) used to relieve depression; SSRI drugs act by moderating levels of the neurotransmitter serotonin.

SELENIUM: a trace mineral that acts as an antioxidant.

SEMEN: male ejaculatory fluid containing sperm and various proteins.

SENSITIVITY: the ability of an organism to respond to a drug or other agent. Sensitivity also refers to a statistical measure of the accuracy of a screening test, that is, how likely a test is to label as positive those who have a disease or condition. Contrast with specificity.

SEPSIS: infection.

SEROCONVERSION: the development of antibodies against a pathogen; the change in a person's antibody status from negative to positive.

SERONEGATIVE: lack of antibodies against a pathogen in the blood.

SEROPOSITIVE: presence of antibodies against a pathogen in the blood.

SEROSTATUS: the presence or absence of antibodies against a pathogen in the blood.

SERUM: the fluid, noncellular portion of blood that remains after coagulation; lymphatic fluid. See also plasma.

SERUM HEPATITIS: see hepatitis B.

SEXUALLY TRANSMITTED DISEASE (STD, SEXUALLY TRANSMITTED INFECTION, STI, VENEREAL DISEASE): a disease (e.g., chlamydia, gonorrhea, syphilis, herpes, HIV) that is transmitted through sexual contact.

SGOT: serum oxaloacetic transaminase. See aspartate aminotransferase.

SGPT: serum glutamic pyruvic transaminase. See alanine aminotransferase.

SHEDDING: release of infectious particles (e.g., bacteria, viruses) into the environment.

SHO-SAIKO-TO: a traditional herbal liver formula containing bupleurum.

SIALADENITIS: Sialadenitis is an inflammatory disease that causes dry mouth and eyes and is associated with hepatitis C infection. Sialadenitis destroys the salivary glands.

SIDE EFFECT: see adverse reaction.

SILIBIN: an active component of milk thistle.

SILYMARIN: see milk thistle.

SIMEPREVIR:(brand name OLYSIO) is used to treat chronic hepatitis C in combination with pegylated interferon and ribavirin. Simeprevir is a hepatitis C virus protease inhibitor. Simeprevir plus sofosbuvir and ribavirin is used to treat genotype 1.

SINUSOIDS: cavities through hepatic or liver tissue allowing exchange of nutrients and other substances between blood and hepatocytes (liver cells).

SJÖGREN'S SYNDROME: an autoimmune disorder in which the immune system attacks fluid-producing exocrine glands, leading to dry eyes, mouth, vagina, etc.

SOC: see standard of care.

SODIUM: an element and electrolyte and a component of salt that helps to regulate cell fluid balance.

SOFOSBUVIR: (brand names HARVONI: SOVALDI) is used to treat chronic hepatitis C.

SOVALDI: see sofosbuvir.

SQ: see subcutaneous.

SPECIFICITY: a statistical measure of the accuracy of a screening test.  Specificity measures the proportion of negatives which are correctly identified (e.g., the percentage of healthy people who are correctly identified as not having the condition).  Contrast with sensitivity.

SPIDER ANGIOMA: a mass of visible veins on the skin surface; may be a symptom of chronic liver damage.

SPLEEN: an immune system organ located in the abdominal cavity. The spleen produces blood cell in the fetus, and later removes old red blood cells and platelets from circulation.

SPLENOMEGALY: enlargement of the spleen.

SPONTANEOUS BACTERIAL PERITONTIS: bacterial infection of ascitic fluid in the abdominal cavity.

SSRI: see selective serotonin reuptake inhibitor.

STAGE I: the earliest stage of liver damage, characterized by liver inflammation without fibrosis or cirrhosis.

STAGE II: a stage of liver damage characterized by fibrosis in a single area of the liver.

STAGE III: a stage of liver damage characterized by fibrosis in adjacent areas of the liver.

STAGE IV: the most advanced stage of liver damage, characterized by cirrhosis and loss of normal liver architecture.

STANDARD INTERFERON: the type of interferon-alpha traditionally used to treat HCV. Brand names include Intron-A and Roferon-A.  Also see pegylated interferon.

STANDARD OF CARE: the level of care that all persons with a particular illness should receive; the level below which care would be considered substandard.

STANDARD THERAPY: the best or most widely used currently available treatment for a disease.

STATISTICAL SIGNIFICANCE: the probability that a clinical trial result is not due to chance alone. In general, a result of a clinical trial is considered statistically significant if there is a less than 5% probability that the difference observed would occur by chance alone if the treatments being compared were equally effective.

STI: see sexually transmitted disease.

STD: see sexually transmitted disease.

STEATOSIS: buildup of fat tissue in the liver.

STENOSIS: narrowing or tightening of an opening or passage in the body.

STEROID: a family of substances that share a similar chemical structure, including certain hormones (e.g., testosterone) and various drugs.

STROKE (CEREBROVASCULAR ACCIDENT): interruption of the normal flow of blood to the brain due to a blood clot or hemorrhage. Lack of blood flow can lead to brain damage (resulting in symptoms such paralysis) and death.

SUBCLINICAL: disease symptoms that are too subtle to be noticed by a patient, but may be apparent in laboratory results.

SUBCUTANEOUS (SQ): underneath the skin; usually refers to a drug injected under the skin.

SUBJECT: a volunteer participant in a clinical trial.

SUBTHERAPEUTIC: a drug dosage that is too low to be effective.

SUBTYPE: a genetic variation of an organism. Subtypes are a more narrow classification than genotypes, but broader than quasispecies. Genotype 1 HCV is divided into subtypes 1a and 1b.

SUPERINFECTION: the acquisition of a second infection while a previous infection is still present.

SUPEROXIDE DISMUTASE: an enzyme that destroys free radicals.

SUPPLEMENT: a nutrient, usually in pill form, taken in addition to the normal diet.

SUPPORT GROUP: a group of peers with a common condition that meet for mutual emotional support or education.

SURROGATE MARKER: see endpoint.

SUSCEPTIBLE: vulnerable to or potentially able to contract a disease. Also refers to a microorganism that is vulnerable or sensitive to the effects of a drug.

SUSTAINED RESPONDER: a person who maintains a long-term response to treatment. In HCV, a sustained responder has a long-term response (e.g., normal ALT levels, undetectable HCV RNA) that persists after treatment is stopped.

SUSTAINED VIROLOGICAL RESPONSE (SVR): HCV RNA is undetectable at Week 24 post-treatment.  Also called a viral cure.

SVR: see sustained virological response:

SVR12: no virus detected at 12 weeks after completion of treatment.

SVR24: no virus detected at 24 weeks after completion of treatment.

SYMMETREL: see amantadine.

SX: see symptoms.

SYMPTOM (SX): any perceptible change in the anatomy or function of the body that indicates the presence of a disease or condition.

SYMPTOMATIC: showing outward signs or symptoms of a disease.

SYNDROME: a set of symptoms or disease manifestations that occur together.

SYNERGY (SYNERGISM, adjective SYNERGISTIC): an interaction between drugs that produces an effect greater than the expected additive effect of the different drugs used separately.

SYNERGISTIC EFFECT: The interaction of two or more drugs such that their combined effect is greater than the sum of the individual effects when each drug is administered alone.

SYSTEMIC: affecting the whole body.

SYSTEMIC LUPUS ERYTHEMATOSUS (LUPUS): an autoimmune disease characterized by inflammation of connective tissue throughout the body, especially in the joints.

SYNTHESIS: production.



T
TACE: see transcatheter arterial chemoembolization.

T'AI CHI: a traditional Chinese exercise that promotes the health flow of qi.

TAURINE: an amino acid synthesized by the liver that is necessary for many bodily functions.

T-CELL (T-LYMPHOCYTE): a type of immune system white blood cell.

TELAPREVIR: (brand name Incivek): an HCV protease inhibitor (taken in combination with pegylated interferon plus ribavirin) previously used to treat people with HCV genotype 1.

TELBIVUDINE (Brand name TYZEKA): A nucleoside analogue medicine used to treat chronic hepatitis B. Telbivudine is not recommended as first line of HBV treatment because of the high rate of drug resistance.

TENOFOVIR: (Brand name VIREAD): a nucleoside analogue medicine used to treat chronic hepatitis B and HIV. Tenofovir has a low drug resistance profile so it is recommended as a first line of treatment.

TERATOGENICITY: causing birth defects or malformation of the fetus.

TERMINATED: a study that has been stopped or discontinued before completion.

TESTOSTERONE: the primary male sex hormone or a synthetic analog. Testosterone stimulates the development of male secondary sex characteristics and the production of sperm.

THIOCTIC ACID: see alpha lipoic acid.

THISYLIN: an active component of milk thistle.

THROMBOCYTE: (PLATELET): a type of blood cell responsible for normal blood clotting.

THROMBOCYTOPENIA: an abnormally low number of platelets, which may result in abnormal bleeding and easy bruising.

THROMBOCYTOPENIC PURPURA: a condition caused by a lack of platelets. Small blood vessels under the skin bleed, resulting in purplish discolorations.

THROMBOPOIETIN (TPO): a cytokine that stimulates the production of platelets.

THROMBOSIS: development of blood clots within blood vessels or the heart.

THYMIC FACTOR: a hormone produced by the thymus gland or a synthetic substance that has a similar effect. Thymic factors help promote immune system activity, and are under study as a treatment for HCV. Factors include thymosin, thymopentin, and thymopoietin.

THYMOPOIETIN: see thymic factor.

THYMOPENTIN: see thymic factor.

THYMUS GLAND: a gland in the chest that plays an important role in immune system function; the gland is active in children, but less so in adults.

THYROID GLAND: an organ at base of the neck that produces thyroxin and other hormones involved in regulating metabolism.

THYROIDITIS: inflammation of the thyroid gland.

TID: taken three times daily.

TINNITUS: ringing or buzzing in the ears.

TMA: see transcripton mediated amplification.

TOCOPHERAL: see vitamin E.

TOLERABILITY: the degree to which a drug or other agent produces adverse side effects.

TOPICAL: a medication applied to the skin surface.

TOXICITY (adjective TOXIC): the quality of being poisonous or harmful; often used to refer to drug side effects.

TOXIN: a harmful or poisonous agent.

TRACE ELEMENT: a substance needed in very small amounts for the proper functioning of the body.

TRADITIONAL CHINESE MEDICINE (TCM): an ancient Asian system of healing that focuses on achieving internal balance. TCM practitioners use methods such as acupuncture, moxibustion, herbal formulas, and exercises such as t'ai chi and qigong to restore the flow of qi (vital energy) within the body.

TRANSAMINASE: see aminotransferase.

TRANSCATHETER ARTERIAL CHEMOEMBOLIZATION (TACE): a treatment for hepatocellular carcinoma that involves the injection of chemotherapeutic drugs into the tumor's blood supply.

TRANSCRIPTION (verb TRANSCRIBE): the process of copying genetic material.

TRANSCRIPTON MEDIATED AMPLIFICATION (TMA): a recently developed, highly sensitive viral load test.

TRANSFUSION: the transfer of blood or blood components from one individual to another (or back to the donor, in the case of autologous transfusion).

TRANSIENT: short-lived; not permanent.

TRANSJUGULAR LIVER BIOPSY: a type of liver biopsy in which a sample is taken through the jugular vein in the neck.

TRANSMISSION: spread of a pathogenic organism from one person to another.

TRANSPLANT: surgical transfer of an organ from one person to another.

TRANSIENT ELASTOGRAPHY:  see FIBROSCAN

TREATMENT-EXPERIENCED: a person who has had prior treatment for a particular condition.

TREATMENT-NAIVE: a person who has never been treated.

TREATMENT RESPONSE: a favorable outcome from therapy. Several different measures are used to describe HCV treatment response, including biochemical response, histological response, end-of-treatment response, and sustained virological response.

TRIAL: see clinical trial.

TRIGLYCERIDE: an organic compound made up of a fatty acid plus glycerol.

TROUGH LEVEL: the lowest level of a drug reached between doses. Contrast with peak level.

TSH: thyroid stimulating hormone.

T-SUPPRESSOR CELL: a type of T-cell that helps to regulate and control immune system activity.

TUMOR: an abnormal growth of cells. Tumors may be malignant (cancerous) or benign (harmless).

TWINRIX: brand name of a combination hepatitis A/hepatitis B vaccine.

TX: treatment, transplant.

TYPE 1 DIABETES: see diabetes mellitus.

TYPE 2 DIABETES: see diabetes mellitus.



U
ULTRA-RAPID VIROLOGICAL RESPONSE (URVR): undetectable HCV RNA at Week 2 of treatment.

ULTRASONOGRAPHY (ULTRASOUND): a method of visualizing the internal parts of the body, or a fetus within the uterus, using sound waves.

UNBLINDED: see blinding.

UNCONTROLLED TRIAL: a clinical trial in which all participants receive the experimental treatment and none receive a standard treatment or placebo for comparison.

UNDETECTABLE (UNQUANTIFIABLE): a term used to describe a viral load (amount of viral RNA) that is below the level of detection of the test being used.

UNIVARIATE ANALYSIS: a statistical analysis that takes into account a single factor or variable.

UNIVERSAL PRECAUTIONS: techniques used by health-care providers (e.g., use of gloves and face masks, proper disposal of used syringes) to prevent the spread of infectious diseases.

UNOS (United Network of Organ Sharing): a non-profit organization that runs the Organ Procurement and Transplant Network which oversees the fair distribution of organs for transplantation.



V
VACCINE: a preparation administered to stimulate an immune response to protect a person from illness. A vaccine typically includes a small amount of a killed or inactivated microorganism, or genetically engineered pieces. A therapeutic (treatment) vaccine is given after infection and is intended to reduce or stop disease progression. A preventive (prophylactic) vaccine is intended to prevent initial infection.

VARICEAL HEMORRHAGE: bleeding from stretched and weakened blood vessels, especially in the esophagus or stomach.

VARICES (adjective VARICEAL): an abnormally dilated or swollen vein, artery, or lymph vessel resulting from portal hypertension.

VASCULITIS: blood vessel inflammation.

VEIN: Any of the membranous tubes that form a branching system and carry blood to the heart from other organs.

VERTICAL TRANSMISSION (PERINATAL TRANSMISSION): transmission from a mother to a fetus or newborn. Vertical transmission may occur in utero (in the womb), intrapartum (during birth), or postpartum (e.g., via breast-feeding).

VICTRELIS (brand name boceprevir): an HCV protease inhibitor taken in combination with pegylated interferon plus ribavirin that was previously used to treat people with HCV genotype 1.

VIRAL CURE: see sustained virological response.

VIRAL HEPATITIS: a type of hepatitis caused by a virus. The most common types are hepatitis A, hepatitis B, and hepatitis C.

VIRAL LOAD: the amount of virus in the blood or other tissues, usually expressed in terms of copies of viral genetic material (RNA or DNA). The presence of genetic material indicates that a virus is actively replicating.

VIRAL LOAD TEST: an assay that measures viral load; the bDNA, PCR, and TMA tests are most often used to determine HCV viral load.

VIRAL RESPONSE: see virological response.

VIREMIA (adjective VIREMIC): the presence of a virus in the blood.

VIRION: a complete virus particle.

VIROLOGICAL FAILURE: failure of a treatment to suppress a virus.

VIROLOGICAL RESPONSE: reduction in viral replication in response to treatment. In HCV, a complete virological response means that a person's HCV RNA becomes undetectable with treatment.

VIROLOGY: the study of viruses and diseases caused by viruses.

VIRULENCE (adjective VIRULENT): aggressiveness, ability to cause disease.

VIRUS: a microscopic infectious organism that is unable to grow or replicate outside of a host cell. Viruses integrate their genetic material (DNA or RNA) into a host cell and take over the cell's biological mechanisms to reproduce new virus particles.

VITAMIN: an organic substance that acts as a coenzyme or regulator of metabolic processes; vitamins are crucial for many vital bodily functions.

VITAMIN A: a fat-soluble vitamin synthesized from beta carotene within the body that has antioxidant properties and is important for proper immune system functioning. Excess vitamin A can be toxic to the liver.

VITAMIN B: a complex of several important vitamins including B1 (thiamin), B2 (riboflavin), B3 (niacin), B6 (pyridoxine), and B12 (cobalamin).

VITAMIN B12 (COBALAMIN): a vitamin needed for red blood cell production and DNA synthesis and repair. Vitamin B12 deficiency may result in anemia, neurological dysfunction, and changes in mental status.

VITAMIN C (ASCORBIC ACID): an antioxidant vitamin that protects cells from oxidative damage. Vitamin C deficiency may result in poor healing, easy bruising and anemia.

VITAMIN D: a fat-soluble vitamin that is important for mineral metabolism and which may play a role in immune function. Excess vitamin D can be toxic to the liver.

VITAMIN E (TOCOPHEROL): an antioxidant vitamin that protects cell membranes from oxidative damage.

VITAMIN K: a substance important for blood clotting.

VITAMIN P: see bioflavinoid.

VITILIGO: a condition in which there is loss of pigmentation – usually around the mouth, eyes, nose, elbows, knees and wrists.



W
WASHOUT PERIOD: the time it takes for a drug to be cleared from the body after it is discontinued.

WASTING SYNDROME: a condition characterized by atrophy of lean body mass and involuntary weight loss.

WATER-SOLUBLE: capable of being dissolved in water. Contrast with fat-soluble.

WBC: white blood cell. See leukocyte.

WELLFERON: brand name of lymphoblastoid interferon-alpha-n1.

WESTERN BLOT: an antibody test used to confirm a positive ELISA test for HIV.

WESTERN MEDICINE: allopathic medicine; the type of medical practice.

WHITE BLOOD CELL (WBC): see leukocyte.

WILSON'S DISEASE: a hereditary disorder affecting copper metabolism.

WINDOW PERIOD: the time between exposure to a microorganism and the production of sufficient antibodies to be detected on a test.

WNL: within normal limits.



X
XENOGRAFT (XENOTRANSPLANT): a transplant of an organ or tissue from a different species.



Y
(no definitions are posted at this time)

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Z
(no definitions are posted at this time)



Biology Terms - Glossary of Biology Terms and Definitions

A
Abdomen: Abdomen in mammals is the portion of the body which is located below the rib cage, and in arthropods below the thorax. It is the cavity that contains stomach, intestines, etc.

Abscission: Abscission is a process of shedding or separating part of an organism from the rest of it. Common examples are that of, plant parts like leaves, fruits, flowers, and bark being separated from the plant.

Accidental: Accidental refers to the occurrences or existence of all those species that would not be found in a particular region under normal circumstances.

Acclimation: Acclimation refers to the morphological and/or physiological changes experienced by various organisms to adapt or accustom themselves to a new climate or environment.

Active Transport: The movement of cellular substances like ions or molecules by traveling across the membrane, towards a level of higher concentration, while consuming energy.

Activity Space: The entire range of climatic and environmental conditions suitable to normal functions, process, and activities of a living organism.

Adaptation: Adaptation refers to the genetic mechanism of an organism to survive, thrive, and reproduce by constantly enhancing itself, by altering its structure or function, in order to become better suited to the changing environment. Read more on adaptations in desert animals.

Adaptive Radiation: The evolutionary diversification from an ancestral group of organisms, into a number of newer and more specialized forms, each suited to live in new habitats. Read more on animal adaptations.

Aerial Behavior: Aerial behavior is a type of behavior that deals with communicative or playful behavior. It is most seen in whales and dolphins when they surface above water to either jump, leap, or just flit across.

After-Shaft: A small supplementary feather, growing from the underside of the base of the shafts of a body feather. It is found in many birds and essential to keep them warm.

Aigrette: A tuft of long and loose feathers used by breeding herons and egrets, during courtship displays.

Air Sac: A thin-walled, air filled structure which is a part of the respiratory system of birds. The air passing through the air sac aids in their breathing and temperature regulation.

Airfoil: A structure designed to lift and control the airflow by making use of different levels of air waves. A bird in flight uses the concept of airfoil to control its speed.

Alligator: A broad snouted crocodilians of the genus Alligator found in subtropical regions. This reptile is known for its sharp teeth and powerful jaws.

Allopatric: Organisms that occur, originate, or occupy in separate geographical areas.

Alpha Diversity: A measurement of species richness in a natural unit (specified area) consisting of all plants, animals, and micro-organisms in a habitat functioning together.

Altruism: Instinctive behavior performed towards the welfare of others, sometimes at personal cost.

Alula: A set of quill-like feathers located close to the base of the primary feathers that play a part in increasing or decreasing the bird's lift by affecting the airflow of the wings.

Alveolus: A small angular cavity, sac, or pit in the body.

Ambulacra: This term refers to echinoderm's five part radial areas (undersurfaced side) from where the tube feet protrude as well as withdraw.

Amnion: The innermost delicate embryonic or fetal membranes of higher vertebrates like mammals, birds, and reptiles.

Amniotic Egg: Eggs found in a water-impermeable, amniotic membrane, filled with fluid in the amniotic cavity, that can develop on land without dehydrating themselves.

Amphibians: Animals that can survive and live on land as well as in water. Amphibians are vertebrates and cold-blooded.

Amphisbaenian: A long reptile (worm-like) with a short tail and ring-shaped scales that has well adapted itself to burrowing.

Amplexus: Mating position of the frogs and toads, in which the female sheds the eggs into the water and the male fertilizes it. Fertilization takes place outside the female's body.

Anapsid: An extinct subclass of reptiles except for the turtles, that have no opening in the temporal region of the skull.

Anastomosis: A network of intersecting or connecting blood vessels, nerves, or leaf veins that form a plexus.

Animalia: The taxonomic kingdom of animals that includes organisms that are multicellular, eukaryotic, (having cells with membrane-bound nuclei) and heterotropic (require organic compounds for nourishment).

Annelida: The taxonomic group of animals that includes coelomate, and elongated and segmented invertebrates such as leeches, earthworms, marine worms, etc.

Antenna: A sensory apparatus found on the heads of insects and most arthropods. It usually occurs in pairs.

Antler: One pair of bony, deciduous, and branched hornlike structure found on the head of a deer, moose, elk, etc.

Anus: An opening at the lower end of the digestive tract through which all solid waste is eliminated from the body.

Apomorph: A new specialized trait in an evolving organism which is completely different from its ancestral line.

Aposematic: Color construct characteristics in animals (changing color), either as a warning to other animals or as a self defense mechanism.

Arboreal: Arboreal refers to animals that have adapted themselves to live and move in the trees.

Arthropod: A group of invertebrate animals such as the insects, crustaceans, arachnids, centipedes, etc that are characterized by a exoskeleton and a segmented body with jointed appendages.

Artificial Selection: A selection process where the breeder chooses the animals for mating and producing offspring of desired inheritable qualities.

Aspect Diversity: It is the measure of the different physical appearances that are found in a group of species living in a common habitat and are hunted by other animals that use visual hunting skills to identify and kill their prey.

Auriculars: Auriculars is a set of feathers that are found near a bird's ear openings.

Autonomic Nervous System: The part of the vertebrate nervous system that regulates involuntary action of an animal's internal organs like the intestines, heart, and glands.

Autotroph: An organism capable of acquiring nourishment from its surrounding environment using photosynthesis or chemosynthesis as opposed to ingesting another organism.

Aves: A class of vertebrates comprising the entire bird family.


B
Balanced Polymorphism: A situation where more than one allele is maintained in a population, which is the outcome of the heterozygote being superior to both homozygotes.

Baleen: Baleen whales are those whales that filter plankton for ingestion, out of large quantities of water. Baleen is the fibrous structure in their mouths, usually referred to as baleen plates, that enable them to feed in this way. They do not have teeth.

Banding: The manner in which a metal or plastic band is attached to the legs of birds and other animals. This is done with the purpose of identifying the individual/creature at the time of recapture.

Barbel: Often found on fish, a barbel is a slim, whisker-like tactile organ located near the mouth. In some fish, they contain the taste buds, and assist the fish to locate food in murky water.

Barbicels: Barbicels are tiny curved structures on barbules, that connect contiguous barbules to form the firm, mesh-like structure of the feather vane.

Barbs: The barbs are attached to the main shaft of a feather, and make up its vanes.

Barbules: Barbules are tiny structures that emerge from the barbs of a bird's feather. They interlock, overlap, and knit together, making the feather solid and stiff.

Basic Plumage: Among the bird species that molt only once a year, the basic plumage are those feathers they have on them throughout the year. Whereas, among species that molt twice annually, the basic plumage (in most cases) are the feathers that grow after the first complete molt, and is present at the time of the bird's non-breeding season.

Batesian Mimicry: In a situation where a harmless species has evolved to replicate the warning signal given by a harmful species (directed at a common predator), Batesian mimicry occurs.

Beak: The protruding part of the mouth of several groups of vertebrates, including some cetaceans. Birds use them not only to eat, but also to groom, kill prey, manipulate objects, in courtship, and to feed the young.

Benthic: A Benthic zone is the ecological region that encompasses the bottom most level of any body of water, be it a river, lake, or ocean. When used in conjunction with a living organism, it refers to bottom-dwelling.

Beta Diversity: A term of measurement, that gauges the variety of organisms in a region. It is impacted by the turnover of species among habitats.

Bilateral Symmetry: This type of symmetry is exhibited by most animals, and simply implies that, if a line were drawn down the middle of the body, both sides would be equal and symmetrical.

Bill: The projecting mouth of a bird. It is the same as a Beak.

Binocular Vision: An animal with this kind of vision has eyes that are projected forward, due to which the field of view overlap, enabling the creature to judge depth.

Biodiversity: A term of measurement, that gauges the diversity of organisms in a habitat or ecosystem. This measurement can be made based on the number of species or genetic variation that exist within an ecosystem or region.

Biogeography: It is a term used to define the study of the geographic distribution of organisms throughout a region over a given period of time. It is carried out with the aim of examining where organisms dwell, and at what populations.

Biome: A region that is defined based on its climate and geography, which has ecologically similar communities of plants, animals, and soil organisms. The similarity is based on plant structures (such as trees, grasses and shrubs), plant spacing (forest, savanna, woodland), leaf types (such as needle-leaf and broad-leaf), and climate.

Biota: They constitute the living components (flora and fauna) of an ecosystem, biome, or habitat.

Blowhole: A blowhole is an opening on the top of a cetacean's head, from which air is inhaled and exhaled.

Bipedal: Bipedalism is a manner of moving on land, where the organism progresses using only its two rear limbs, or legs.

Birth Rate: The term is the average number of young produced within a specific period of time. It is calculated per individual, and is usually communicated as a function of age.

Book Lung: It is an organ used for respiration, and is part of the body system of arachnids, such as spiders and scorpions. The book lung is located inside the ventral abdominal cavity.

Bow Riding: It is an activity carried out by cetaceans (most commonly dolphins), in which they swim or drift along the crests of waves in the ocean.

Breeding System: A breeding system includes all the different breeding behavior (polygyny, outcrossing, or selective mating) of a population, and the methods in which the members of the population adapt to them.

Brilles: The German word for 'glasses', it is a transparent, immovable layer of scale/skin that covers the eyes of some creatures, such as snakes and lizards, and provides a protective layer.

Bristles: Bristles are long, stiff strands of hair or feathers. In birds, they are situated near the mouth or eyes. Their function may be to assist the bird in eating and give protection to the eyes.

Brood Parasite: A brood parasite is an organism (usually a bird) which manipulates another individual of the same or different species to raise its offspring. A method usually adopted to do this is to lay eggs in another birds nest.

Brood Parasitism: The method adopted by one organism to make another individual of the same or different species to raise its offspring. In case of birds, this is done by laying ones eggs in another birds nest.

Brood Patch: Located on the lower abdomen of birds, this patch develops by the shedding of feathers in this area, and the consequent thickening of the skin, after which it becomes densely populated with blood vessels. The brood patch is used to incubate the eggs and keep the young warm.

Brood Reduction: When a clutch of eggs hatch sequentially, if there is inadequate food, brood reduction takes place. This happens when the weakest chick or chicks, being deprived of food either fail to survive out of starvation, or are devoured by their stronger siblings.

Brooding: The practice of birds, where the parent birds continue to provide warmth to their young, during the time when they are unable to maintain their own body temperatures.
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C


Caching: Storing of food for later use, when food is not available or is short in supply.

Caiman: A tropical American crocodilian amphibian, found in Central and South America.

Calamus: It is the hollow base of a feather shaft, which attaches the feather to the skin.

Calcereous: Calcium contained parts such as shells, bones, and exoskeletons, which protects an animal.

Call Matching: This is a behavioral trait, often displayed by members of the finch family. This refers to the male and female of a pair duplicating each others flight call, vocally.

Camouflage: A feature common to invertebrates, which helps them blend with their surroundings using its skin colors or patterns.

Canine Tooth: A single point tooth that is shaped and used for piercing and holding on to food. It is located near the front of the jaw, and is prominently seen in carnivores.

Carapace: A hard shell which shields the dorsal side of an animal's body. It is used more specifically to refer to the upper side of a tortoise or turtle's shell.

Carnasial Tooth: A premolar tooth, which is used to efficiently tear and slice meat of prey. This tooth is seen only in the carnivores.

Carnivore: A mammal belonging to the order Carnivora, that sustains by eating the flesh of other animals.

Carrying Capacity: It is the maximum population of a particular species, which can be supported for an indefinite period of time in a particular environment.

Caruncle: A fleshy outgrowth, without feathers, seen on the neck and face of a bird. It is also referred to as fowl's comb and usually seen in the turkey family.

Casque: A formation on the head resembling a helmet, that is located on the head of a lizard.

Caste: A group of species, which shares similar features, form, or behavior and belong to the same social group.

Central Nervous System: A part of the nervous system, made up of inter-neurons, which exercises control over the nervous system.

Centrifugal Tail Molt: The process of shedding and replacing of feathers of a birds tail, that starts with the replacement of the innermost pair of feathers first and then moves from the center outward.

Cephalization: It is a tendency within animals, with localization of neural control and sensory organs located at an end of the body, usually near the head.

Cere: A raised and membranous covering, that is located at the base of the upper mandible in a bird.

Cetaceans: Mainly marine mammals belonging to the Cetacea species. Toothed whales and toothless filter feeding whales are among those that belong to this catergory.

Character Displacement: Adaptations of different sets of characteristics in two similar species, brought about by overlapping territories, resulting in competition.

Cladistics: It is the study of evolutionary history of a group of organisms, especially as shown in a family tree.

Clappeing: Slapping of the upper and lower parts of bills together, as a non vocal form of communication, seen especially in birds like storks.

Climax: The steady, end stage in the ecological evolution of a plant or animal species.

Climograph: Annual cycle of temperature and rainfall for a particular geographical area depicted in a graphical format.

Cloacal Spur: A claw in boas and pythons, which is an extremity of the pelvic girdle. It is used by the male snake, while courting.

Clutch: Eggs or young offspring of a species produced in single breeding attempt by a female.

Cnidaria: A name given to the invertebrate phylum Coelenterata, the emphasis is given to the stinging characteristic of the phylum, which makes up its basic structure comprising nettles, which are generally toxic in nature.

Coelenterates: An invertebrate belonging to Coelenterata phylum characterized by a single interval cavity used for digestion, excretion, and for other survival activities and which has tentacles on the oral end. Hydras, jellyfish, corals, and sea anemones belong to this group.

Colt: Male horse less than four years of age. For interesting facts about horses, click here.

Competition: When two or more individuals compete for the same set of available and limited resources, affecting both the parties negatively.

Conditioning: A learning method either using a stimulus - response, or a reward - punishment method, in which associations are made.

Constriction: This is a method used by non-venomous snakes to tightly grip and suffocate their prey, by coiling around the prey.

Contour Feathers: The feathers which form the topmost layer of a bird's feathers, including the wings and tail, which gives the bird its characteristic look.

Convergent Evolution: The similar structural appearance in organisms, which have different lines of descent.

Corallum: The skeleton of a zoophyte, which can be calcareous or in the formation of horns. For example, the set of parallel vertical grooves which are present on the sides of salamanders and newts.

Countershading: The development of dark colors on the areas exposed to the sun and light colors on the undercarriage.

Creche: Flock of birds, not necessarily belonging to the same species that flock together for protection.

Critical Habitat: A habitat which is critical for the survival and conservation of a species, designated by a rule published in the Federal Register.

Crocodile: Reptile belonging to the order crocodylia, which inhabits tropical regions. Note: Crocodiles differ from alligators.

Crop: Expandable pouch found in the esophagus of some birds.

Cryptic: These refer to the characteristics that help in concealing an animal.

Consumer: An organism, often an animal, which feeds on plants or other animals.
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D


Dabble: Bird behavior pertaining to foraging for food with their beaks or bills from shallow water.

Death Rate: The average number of newborns or young ones dying within a specified period of time. This value is in comparison to the population of the desired species.

Definitive Plumage: The plumage of a bird attained after the shedding of all previous feathers that do not change significantly in color or pattern, as long as the bird lives.

Delayed Plumage Maturation: A common phenomenon seen in male birds where the definitive plumage is delayed due to a number of factors.

Delist: The act of removing an animal species from the list of endangered, threatened, and vulnerable wildlife list.

Delphinidae: A group of marine mammals that belong to the family Delphinidae and the Order Cetacea, like dolphins and their relatives.

Deme: A local breeding that interbreeds organisms of the same species or individuals.

Detritivore: Organisms that feed on dead, decomposed, or organic waste.

Detritus: Organic matter that is either freshly dead or partially decomposed.

Developmental Response: The development of morphological and physiological qualities of an organism in response to prolonged or changing environmental conditions.

Diapause: A period of inactive hormonal development as a response to unfavorable environmental conditions. This is a temporary phase.

Diffuse Coevolution: Evolution of a species depending upon the evolution of some other species, which itself may be evolving depending on some other factors. Coevolution is basically, the evolution of groups depending on each other together, in order to survive.

Diffuse Competition: The weak interactions between species that are ecologically and distantly related.

Dimorphism: The occurrence or existence of two forms within the same species bearing distinct structure, features, coloration, etc.

Diving Reflex: A developed reflexive response to diving, found in most aquatic mammals and birds, that are characterized by complex physiological changes and adaptations.
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E


Evolution: At the most basic level, evolution is change that takes place over time. In reference to lifeforms, evolution refers to the genetic changes observed amongst the population of organisms from generation to generation. Read more on theory of evolution.

Ecological Isolation: It refers to the situation where closely related (sometimes virtually indistinguishable) species live in the same territory, but slight differences in their niche causes them to reproduce in isolation to the others.

Ecological Release: It refers to the progression in which a species expands its living habitat as well as the resources it utilizes into areas that have a lower density of species in terms of diversity.

Ecomorphology: It is the study of the relation between an individual's ecological role, its form, and structural adaptations.

Ecosystem Approach: This is a method of resource management that acknowledges that the different components of an ecosystem (structure, function, and species composition) are interlinked, and this factor must be taken into consideration, while restoring and protecting the ecosystem's natural balance.

Ectoparasite: An organism, such as a tick, that latches itself to the surface of its host, in order to survive.

Ectothermy: Refers to an organism's ability to maintain its body temperature by availing heat from the environment, either by absorbing radiation or through conduction.

Effective Population Size: The average size of a population expressed in terms of individuals assumed to contribute genes equally to the next generation; generally smaller than the actual size of the population, depending on the variation in the reproductive success among individuals.

Egestion: Process of removal of undigested food material.

Egg Dumping: Refers to a bird laying its eggs in the nest of another, with the purpose of making the host bird to hatch and raise its young.

Elliptical: The shape of an egg which is widest in the middle and rounded at both ends.

Embryo: An animal or plant that is in its nascent stages of development and is usually still contained within the seed, egg, or uterus.

Endangered Species: The entire population of organisms (plant or animal) that face extinction due to a steady reduction of their numbers. This may be the outcome of environmental changes, loss of habitat, or predation.

Endoparasite: This type of organism or parasite (such as tapeworm) exists and feeds inside the bloodstream or tissue of its host.

Endothermic: The ability of an organism to constantly maintain its body temperature, usually keeping itself warm, irrespective of the external or surrounding conditions.

Endothermy: The ability of an organism to maintain its body temperature, by generating heat metabolically.

Estivation: Similar to hibernation, it is a period of inactivity that the animal goes into, during a dry hot season.

Eyeshine: The phenomenon when light is shone into the eye of certain animals and birds, the pupil seems to glow. This effect is created by the layer of tissue called tapetum lucidum that lies immediately behind the retina.
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F


Facial Shield: Some birds, such as the Eurasian coot, have a hard plate on their forehead called a facial shield, which serves as a display ornament.

Fallout: Refers to those birds that need to land while migrating, in areas they would not normally inhabit, due to harsh weather.

Family: It is a term of classification of living things, in which this group falls below an order. It is further divided into one or more genera. The ranks start with life, followed by domain, kingdom, phylum, class, order, family, genus, and species.

Fang: Fangs are long, pointed teeth located in the front of the mouth. In mammals, these fangs are called canine teeth and are used for tearing flesh. In snakes, they are used to inject venom into the victim.

Fauna: All the animal life that exists in a particular area during a specific period of time.

Feces: Indigestible waste products expelled from an organisms digestive tract. Usually referred to as stool.

Fecundity: In a general sense, it refers to an organisms ability to reproduce. In biology, it refers to a females potential capacity to reproduce, based on the number of gametes (eggs), seed set, or asexual propagules.

Femur: In vertebrates having four limbs the femur is the upper bone of the hind limb. In insects, it is the third segment in the leg.

Feral: It is a term used to refer to an animal that has been domesticated, but has escaped and returned to being wild, while still living in its current environment. Cats, Goats, and pigs are examples of such animals.

Fetus: A fetus is a developing organism, which has moved beyond the embryonic stage, but is yet to be born.

Filly: A female horse that is four years or younger in age.

Filter Feeder: Organisms that feed by sieving water for food particles, with the help of special filtering structures in their mouths. Clams, sponges, krill, and baleen whales use this method.

Fitness: The measure of an individual's genetic contribution to the next generation's gene pool.

Fledge: It is that stage in a young bird's life, when the feathers and wing muscles are developed and the bird is capable of flight. Alternately, it is also used to describe the act of raising chicks to a fully grown state by the parents.

Fledgling: Is a young bird that has recently fledged, but is still being fed and cared for by the parents.

Flight Feathers: Describes the stiff, large feathers of the tail and wings of a bird that are essential for flight.

Foal: A male or female horse that is up to six months old.

Food Chain: The food chain is the transfer of life-giving energy from one organism to another, which is compatible to receive the same form of energy that was passed on, when the organism perished. Read more on the desert food chain.

Food Web: A food web comprises a set of interconnected food chains which exist within an ecosystem.

Founder Effect: In terms of describing the genetic outcome of a new population being established by a very small number of individuals, from a larger population. The founder effect refers to the loss of genetic variation.

Frugivorous: Fruit-eating living being. A frugivore is any organism whose preferred food type is fruits.

Functional Response: The relationship between prey and predator, or deviation in the rate of exploitation of prey by an individual predator due to change in the prey density.
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G


Gamma Diversity: This term refers to the measure of biodiversity, which means the total species richness within an area.

Gaping: The open width of space, created by forcefully opening the jaws or mandibles of a vertebrate.

Gelding: A male horse that has been spayed.

Generalist: Any organism that can survive in a wide-ranging habitat.

Gharial: An Asian crocodile with a very narrow jaw.

Gill: The respiratory organ of any aquatic animal. Its basic function is to help the animal breathe the oxygen dissolved in water.

Gill Arches: Cartilaginous arches located on each side of the pharynx to provide support to the gills of aquatic as well amphibian animals.

Gill Slits: A narrow external opening connected with the pharynx, to allow passage of water, which helps in cleaning the gills.

Gizzard: A chamber found in the lower stomach of animals that facilitates food grinding.

Gonads: The testes or ovaries (sex glands) found in the animal reproductive organ.

Gorget: A small patch on the throat of an organism which is distinguished by its color, texture, and thickness quality.

Guano: Large deposits of substances composed chiefly of the feces of birds or bats.

Gular Fluttering: A cooling mechanism adopted by birds, in which they flap their flap membranes rapidly in the throat to increase evaporation.

Gular Pouch: A bare sac or pouch that can be expanded to accommodate a large prey, or for the show off during courtship display.
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H


Habitat Compression: When local population is forced or restricted within a set boundary, to accommodate more species.

Habitat Expansion: Increase in the habitat (overall area) distribution of the species.

Habitat Patch: A location that encompasses a distinct habitat type.

Habitat Selection: Habitats chosen over other habitats to suit climatic and environmental conditions.

Hacking: Part of the wildlife conservation rehabilitation program, where the animals or birds released in the wild for the first time, are periodically provided with food until they become independent.

Hatchling: A young one that has just been hatched from an egg.

Heat Sensitive Pit: An organ located on each side of the head, below a line from the eye to the nostril of some snakes, especially the vipers. It helps the snake detect its prey.

Herbaceous: Stems and branches that are soft, and not hard and woody.

Herbivore: Grass or plant eating organisms are called herbivores.

Hermaphroditic: Organism that have, as well as are capable of reproducing using both male and female reproductive organs.

Hibernation: To withdraw in a state of seclusion in a dormant condition. Most animals like the bear, prefer the winters to go into hibernation.

Histology: The study of tissues of organisms. It includes its structure, arrangement, functions, make up, etc.

Holotype: A single specimen used as standard type to name, describe, and illustrate, and represent a set of species and subspecies.

Home Range: The habitat that an animal normally lives and uses for daily activities.

Homeostasis: The process of maintaining internal stability of the physiological system of animals, in course of varying external conditions.

Homeothermy: The capacity to maintain the condition of being warm-blooded under all climatic situations.

Humus: Fine organic substance, composed of partial or fully-decomposed animal or plant matter, and found in soil.

Hyoid Apparatus: A veterinary anatomy term for the upper throat bones of the tongue and connective tissues.

Hypostracum: The shell located below all other shell layers in some mollusks.
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I


Ichthyology: A branch of zoology dedicated to the systematic study of fish.

Imago: Sexually mature adult stage in the life of certain insects.

Immature: A young animal or bird, capable of feeding itself, but has yet not reached the stage of sexual maturity.

Imprinting: It is a process of phase sensitive learning, where the young animals follow the first moving thing they see.

Incubation Patch: The featherless patch developed on the abdomen of certain brooding birds, that becomes thick due to high levels of vascularity. This patch comes under direct contact with the eggs during the incubation period.

Insectivore: An organism that feeds chiefly on insects.

Interstitial Skin: The skin found between the scales of a snake.

Introduced Species: Organism that would not normally occur but have been introduced in the habitat.

Invertebrate: Pertaining to organisms without a backbone.

Isolating Mechanism: Prevention of breeding between species due to behavior, morphology, genetics, or a geographical barrier.
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J


Juvenal: Refers to the first covering of feathers on a bird, after it loses its down (undersurface) feathers.

Juvenile: This term refers to a young bird in the stage when it has fledged, or young ones of the animals that have not yet reached its adult form, size, and sexual maturity.
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K


Keratin: A hard insoluble protein substance found in hair, nails of mammals, scales of reptiles and bird feathers. This substance is responsible for the structure of hair, nails, scales, etc.

Kleptoparasitism: A parasitic characteristic of opportunistically stealing food and/or nests from other organisms.
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L


Labial: Labial refers to the lips.

Lanceolate: An elongated shape that is slender and tapers towards the apex or base.

Larva: A premature form of animal or insect awaiting transformation to reach adulthood.

Last Common Ancestor: This term refers to the most recent known and shared common ancestor between two species, as well as individuals.

Lateral: Refers to the side location or view.

Lek: The courtship display for mating of certain animals, where males gather around the females for being selected for copulation.

Life Cycle: Phases of life that animals go through starting from birth, to sexual maturity, till death.

Lift: The airfoil (see airfoil) that controls the movement of the birds when in flight, as well as the force with which the birds fly is termed as lift.

Live Bearing: Animals that bear live young ones, rather than laying eggs are called live bearing.

Loafing Platform: A nest like structure built by few birds that can float on water. These birds keep their young ones in this platform to keep them out of water and afloat.

Lores: The space between the eye and the bill of a bird, or the eyes and tip of the mouth of any animal.

Lung: An internal sac-like chamber that forms the respiratory organ in animals.
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M
Melanism: A condition characterized by a high level of concentration of melanin (black pigmentation) occurring in the coat, skin, or plumage of the animals.

Mendelian Trait: Transmission of hereditary traits from parent organisms to their offspring, the trait mainly emphasizes on a single locus.

Mammalia: Mammalia is a group of animals known as the vertebrates (have backbones) and belong to the class Mammalia.

Mandible: The lower jaw of a vertebrate animal, or the upper or lower part of the beak (bill) in birds.

Mantle: Single or paired set of feathers located on the mid-back of a bird, or an outgrowth that lines the inner surface of the valves of the shell.

Mare: Mare is a female horse that has attained the age of more than four years.

Maxilla: A paired appendage usually located behind the mandibles of arthropods.

Medusa: The sexual stage in the life cycle of a coelenterate, such as a jellyfish or a hydra, in which it is free-swimming.

Meiosis: It is the process of nuclear division in a cell, in which the total number of chromosomes is reduced to half. Meiosis results in the formation of gametes in animals and spores in other organisms. Before the process begins, the DNA in the original cell are replicated during a phase called S-phase and this is similar to that in mitosis. Once the replication is completed, two cell divisions separate the replicated chromosomes into four haploid gametes or spores.

Metamorphosis: It is the process of marked change in the appearance and habits of some animals, as a part of their normal development. Metamorphosis of a caterpillar into a butterfly is one such example.

Migration: The annual movement pattern of animals and birds between their breeding grounds and hibernating sites.

Migratory Overshooting: The phenomenon of traveling beyond the normal distance in migratory birds as well as animals, while being on correct migration travel route.

Mirror-Image Orientation: During migration, birds tend to reverse the orientation of their migratory route in opposite (mirror like image) directions.

Mobbing: An aggressive stand taken by some birds to ward off an intruder or predator from the area.

Molt Migration: Molt migration involves movement of birds from their breeding ground to a temporary location where they shed their feathers, plumage, skin, etc.

Molt: Molt is a process where birds and animals shed their hair, plumage, feathers, skin, horns, etc. to facilitate the growth of new ones.

Morphology: The study of form and structure of organisms.

Mouthparts: An appendage found close to the mouth of some animals, birds, and insects, which they use for all eating functions.

Muscle: Tissues that facilitate movement in animals.

Mysticetes: Whales of the suborder Mysticeti, like Right whales, finback, gray whale, humpback whales, rorquals, etc.


N
Naricorns: The raised, tough, horny nostrils found atop the bird bill.

Nectivorous: Animals, birds, or insects that rely on nectar as a source of food.

Nematocyst: This refers to tiny hairlike structures in coelenterates which is used by them to eject stingers.

Neonate: The phenomenon of producing live young ones instead of laying eggs.

Nephridium: A tube like excretory organ of many invertebrates such as mollusks and earthworms.

Nest Parasitism: The process of laying eggs in the nest of other or own species (not making one).

Nidicolous: The time spent in the nest after its hatched.

Nidifugous: The phenomenon of leaving the nest within a few days of hatching.


O


Obligate: Is an adjective that means "necessary" when used in biology. Also, exhibited by all members of a species without exception.

Odontocetes: Used while referring to any whale of the suborder Odontoceti, such as killer whales, dolphins, and sperm whales. They are characterized by a single blowhole, an asymmetrical skull and rows of teeth. They feed primarily on squid, fish, and crustaceans.

Oscines: Members of the suborder Oscines, of the order Passeriformes. They comprise songbirds that have highly developed vocal organs.

Osteichthyes: Are a taxonomic group of fish that includes the lobe-finned fish (Sarcopterygii) and ray-finned fish (Actinopterygii). They are also referred to as bony fish.

Ostracum: The calcified portion of an invertebrate's shell. While the organism is living, the ostracum is covered by layers of protein forming a periostracum.
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P


Partial Molt: Partial molt is a process where some of the bird's feathers get replaced.

Passerine: Pertaining to the order Passeriformes (type of a bird).

Patagium: A thin membrane that extends between the body and the limb to form wings. It is basically the extensible fold of skin found in certain insects, reptiles, and birds.

Peep: A generic name for several sandpiper species.

Pelagic: Organism that live and thrive in open oceans or seas rather than waters adjacent to the land.

Pellet: A mass of regurgitate indigestible matter like fur, feathers, and bones of certain predatory birds like the hawk, owl, etc.

Pentaradial Symmetry: The balanced distribution of duplicate body parts or shapes (sensory and feeding structures) in a five fold circular pattern, i.e body parts arranged in fives or multiples of 5, in a symmetry in organisms.

Periostracum: The external, outermost covering of the shell of some mollusks. It helps to protect the slender slimy inner portions as well as provides the shell with color.

Pineal Eye: A developed third eye in certain cold-blooded vertebrates which helps to regulate body temperature and register light intensity.

Plankton: Microscopic organisms like algae and protozoa that drift on the oceans' currents.

Plastron: The ventral surface of the shell of a tortoise or turtle.

Predator: Organism that feeds off or preys on other organisms for survival.

Preen Gland: It refers to the gland found on the back, at the base of the tail in most birds. This gland secretes oil that the birds use for preening which is part of its feather care activities.

Proboscis: An elongated mouth organ which is an important feeding appendage in organisms.

Pulmonate: Land snails and other air breathers belonging to Pulmonata Subclass and Sorbeconcha Clade.
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R


Radiation: Evolution of multiple species from a single ancestry, but these species have morphological differences, however, they coexist in the same habitat or spread to different habitats or they have a change of ecological role.

Radula: A rough and raspy tongue normally seen in mollusks, used to grate food.

Range: A particular geographical area in which particular species of organisms are found.

Rare: A species of an organism found in very small numbers and hence, visible with a lot of effort only for a short duration.

Rattle: Shed skin, which is often seen on tail of a rattlesnake, used to make a rattling sound in order to deter predators.

Rectrices: The stiff and main feather of a bird that is used to navigate, when the bird is in flight.

Remiges: Flight feather of a bird used to control direction during flying. Their function is similar to that of the rectrices to a certain extent.

Reptilia: Reptiles or vertebrates, who possess a dry scaly skin and reproduce amniotic eggs. Snakes, lizards, and alligators belong to this category.

Resident: A non-migratory species of birds, which stays in a given geographical area throughout its life.

Reticulated: Species whose veins or nerves are like threads of a net, arranged in a network.

Reverse Migration: Phenomenon wherein the migrating organism migrates in the opposite direction, normal to other migrating species.

Rictal Bristles: A stiff bristle like feather, which grows at the base of a bird's bill.

River Dolphins: A species of dolphins, which dwell in major rivers like the Amazon in Brazil, Yangste in China, and the Ganges in India.

Rostral Scale: Is a scale present on the tip of the upper jaw of a snout, usually seen in snakes.

Rostrum: An anatomical structure, present in a species in the form of a snout, which projects out from the head of the animal.

Rounded: Smallest size elliptical, spherical egg.
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S


Salamander: Any tailed amphibian, that has soft and scaleless skin with a long body, tail, and short limbs.

Saw-Scaling: Action of a snake curving its body in concentric curves and rasping its keeled scales together to make a sawing sound as a warning.

Scale: A thin plate that forms the covering of certain animals. This covering can either be hard or soft depending upon the morphology of the organism.

Scape: A tiny stem like first segment in an insect's antennae, as the shaft of a feather.

Scrape Nest: Unlike normal nest, a shallow depression is made by some ground birds as a nest. This nest has no soft lining.

Scute: A large well-defined dermal bony or horny plate found on many reptiles.

Secondary: It refers to the set of flight feathers on the second segment of a bird's wing.

Sedentary: Organism that are nonmigratory in nature, which means they move about little or not at all from their habitats.

Semi-Precocial: This term refers to hatchlings that are capable of leaving the nest but are dependent on their parents for their feed.

Semiplumes: Semiplumes are a type of feathers that are found under the contour feather on a bird's body. They are responsible for providing insulation as well as some flexibility to the bird.

Shaft: The main stiff stem or midrib of a bird's feather.

Shell: A hard outer covering of an organism made up of carapace and plastron.

Shorebirds: Birds that prefer the coastal area as their habitat.

Songbird: A generic name given to the members of the order Passeriformes.

Spy Hopping: A vertical rise out of the water or tall grasses performed by certain cetaceans or land mammals respectively.

Stallion: A male horse which is more than four years old.

Stoop: To swoop down while in flight for catching a prey.

Strandings: Aquatic mammals that get stranded on the beaches or shores.

Stary: An individual animal that has been left alone or has parted ways with others of its flock during movement or migration.

Subelliptical: An egg that is elongated and tapered towards its rounded ends.

Supplemental Plumage: A third set of feathers found in birds that have three different plumages in their annual cycle of molts. See molts.
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T


Tentacle: The slender, elongated, flexible, appendages found in animals, located near their mouth.

Taiga: Coniferous evergreen forests found in the south of the tundra and north temperate region, characterized by harsh winters.

Tail Slapping: The forceful slapping of tails on the surface of water by dolphins.

Tarsus: The bone, which contributes in making the ankle joint, located between the tibia, fibula and metatarsus in mammals.

Taxon: A word used to group or name species of living organisms.

Taxonomic Classification: The hierarchical system used for grouping and naming species of living organisms.

Taxonomy: A practice used to classify animals with evolutionary relationships, as basis of this classification.

Territory: The area of belonging, which is guarded by animals against intruders, especially belonging to the same species.

Thorax: The part of the body in mammals situated between the neck and the abdomen, just above the diaphragm. In case of insects the part situated between the head and the abdomen, excluding legs and wings.

Threatened Species: A species which has the possibility of becoming endangered in the near future.

Torsion: The asymmetrical positioning of the body achieved, due to twisting and repositioning, during development.

Trachea: The pipe serving as the principal passage for movement of air to and from the lungs, in humans and other vertebrates. It extends from the larynx to the bronchus.

Triangulation: The method used by animals to find out the distance between themselves and their prey using two or more fixed points. This technique is used especially by owls and harriers.

Tribe: A category in the classification of organisms between a genus, which contains one or more genera.

Tubenoses: Vernacular name for members belonging to Procellariiformes species.

Tuberculate: An organism or part of an organism which is covered in fleshy and raised protuberances, also called tubercules.

Turtle: A reptile belonging to the Testudines species, which include both terrestrial and aquatic animals. The trunk of these species is enclosed in a shell.

Tympanic Membrane: It is the membrane which picks up vibrations through a medium and transports them to the inner part of the ear. It is also called the eardrum.

Type Specimen: An organism which is used to represent a particular taxon. It becomes the standard for the original name and to describe the species.
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U


Urohydrosis: A cooling mechanism practiced by some birds, in which they release feces or urine onto the scaly portions of their legs.

Uropygial Gland: This is the same as the Preen Gland. It is located at the tip of the tail of birds. It is known to secret oil.
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V


Vagrant: An individual organism found outside the region that is known for that particular species.

Vane: This term refers to that portion of the feather which is made of flat parallel rows of barbs and is attached to the center stiff part of the feather.

Ventral Scale: Scales found on the underside of the snake's body.

Ventral: Refers to the stomach or belly.

Vestigal: The part of an animal that does not develop during evolution. It is underdeveloped and serves no important function.

Viscers: The organs located in the cavities of the organism body.

Vocal Sac: The flexible membrane of the skin found in male frogs and toads that inflates and acts as amplifier for their mating calls.
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W


Warning Coloration: Distinctive bold color patterns found on certain organisms, that work as a warning to predators.

WatchList: A cooperative project of the National Audubon Society and Partners in Flight that keeps track of declining species, that are not yet threatened or endangered.

Water Vascular System: A system of fluid filled tubes and ducts, that connect with the tube feet of most marine invertebrates. They help in functions such as respiration, feeding, etc.

Wattle: A soft fleshy brightly colored appendage that hangs down from the throat or chin of certain birds.

Weaning: The period where the mother ceases to feed the young ones. This only refers to mammals.

Weanling: A male or female horse that is between the age of six months to one year.

Wing-Bar: A line of color, usually contrasting across the middle, tip, or base of a bird's wing, which has been made by the wing coverts.

Wing-Flicking: Rapid movement made by the bird's wings when it is not in flight and is at rest.
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X


Xenophobic Alliance: A union of individual chimpanzees in a group, which challenges intruders who threaten their territory and boundaries.

Xeric: A habitat which has an extremely dry environment. It also refers to animals who have adapted themselves to such an environment.

Xerophyte: A plant which has adapted itself to a dry environment and is able to conserve water.

Xylophagous: Organisms that feed entirely or primarily on wood.
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Y

Yearling: This term is used to describe both a male and female horse between the age of one and two years.

Yolk: Food that is stored in an egg.
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Z

Zooid: An organism which is capable of existing separately. A number of zooid together function like a single animal, example coral.

Zooplankton: A collection of various species of plankton.

Zooxanthellae: Unicellular, yellow-brown in color algae, which live in the gastrodermis of corals.

Zygodactyly: This is the arrangement of toes formed in birds, in which the outer front toe faces the back, resulting in two toes facing forward and two backward.



Glossary of Microbiology Terms and Definitions


A
Abiotic Factors: Non-living factors that can affect life, like soil, nutrients, climate, wind etc.

Absorption Field: An organized system of meticulously constructed narrow trenches, which are partially filled with washed gravel or crushed stone, into which a pipe is placed. Discharges from septic tanks are passed through these trenches.

Acetogenic Bacterium: An aerobic, gram negative bacteria, that is rod-shaped, which is made of non-sporogenous organisms that produce acetic acid as a waste product.

Acetylene Block Assay: Determines the release of nitrous oxide gas from acetylene treated soil, which is used to estimate denitrification.

Acetylene Reduction Assay: This is used to estimate nitrogenase activity by measuring the rate of reduction of ethylene to acetylene.

Acid Soil: Soil which has a pH value lesser than 6.6.

Acidophile: An organism that grows well in an acidic medium (up to a pH of 1).

Actinomycete: These are gram positive, nonmotile, nonsporing, noncapsulated filaments that break into bacillary and coccoid elements. They resemble fungi, and most are free living, particularly in soil.

Actinorhizae: The association present between actinomycetes and roots of plants.

Activated Sludge: Sludge particles which are produced in raw or settled wastewater, by the growth of organisms in aeration tanks. This is all done in the presence of dissolved oxygen. This sludge contains living organisms that can feed on incoming wastewater.

Activation Energy: The amount of energy required to bring all molecules in one mole of a substance, to their reactive state, at a given temperature.

Active Carrier: An infected person who has visible clinical symptoms of a disease, and is capable of transmitting the disease to other individuals.

Active Site: The location on the surface of the enzyme where the substrate binds.

Adjuvant: The material added to an antigen to increase its immunogenicity, for example, alum.

Aerobic: This includes organisms that require molecular oxygen to survive (aerobic organisms), an environment that has molecular oxygen, and processes that happen only in the presence of oxygen (aerobic respiration).

Aerobic Anoxygenic Photosynthesis: Photosynthetic process which takes place under aerobic conditions. However, this process does not result in the formation of oxygen.

Aerotolerant Anaerobes: Microbes that can survive in both, aerobic and anaerobic conditions, because they obtain their energy by fermentation.

Aflatoxin: A toxin produced by Aspergillus flavus and Aspergillus parasiticus, which contaminate groundnut seedlings. This is said to be a cause of hepatic carcinoma.

Agar: A dried hydrophilic, colloidal substance extracted from red algae species, used as a solid culture media for bacteria and other micro-organisms. Also used as a bulk laxative, in making emulsions and as a supporting medium for immunodiffusion and immunoelectrophoresis.

Agarose: Agarose is obtained from seaweed and is used as a resolving medium in electrophoresis. It consists of non-sulfated linear polymer, which contains D-galactose and 3:6-anhydro-L-galactose alternately.

Agglutinates: The visible clumps that are formed as a result of an agglutination reaction.

Agglutination Reaction: The process of clumping together, in suspension of antigen bearing cells, micro-organisms, or particles in the presence of specific antibodies called agglutinins. This leads to the formation of an insoluble immune complex.

Airborne Transmission: A type of transmission, wherein the organism is suspended in or spreads its infection by air.

Akinete: A resting non-motile, dormant, thick-walled spore state of cyanobacteria and algae.

Alcoholic Fermentation: A fermentation process that produces alcohol (ethanol) and carbon dioxide from sugars.

Alga: Phototrophic eukaryotic micro-organisms, that may be unicellular or multicellular. These include phaeophyta: brown algae, spirogyra, and red algae.

Aliphatic: Pertaining to any member of one of the two major groups of organic compounds, with the main carbon structure as a straight chain.

Alkaline Soil: Soil having pH greater than 7.3.

Alkalophile: Organisms that have an affinity for alkaline media, thus, growing best in such conditions.

Allochthonous Flora: Organisms that are not originally found in soil, but reach there via precipitation, sewage, diseased tissue, and other such means. They do not contribute much ecologically.

Allosteric Site: A non-active site on the enzyme body, where a non-substrate compound binds. This may result in conformational changes at the active site.

Allotype: Any of various allelic variants of a protein, characterized by antigenic differences.

Alpha Hemolysis: A partial clearing zone, greenish in color, around a bacterial colony that grows on blood agar.

Alpha-proteobacteria: One of the five sub-groups of proteobacteria, each with distinctive 16S rRNA sequences. Mostly contains oligotrophic proteobacteria, many of which have distinctive morphological features.

Alternative Complement Pathway: A pathway of complement activation, including the C3-C9 components of the classical pathway. It is independent of the antibody activity.

Alveolar Macrophage: A highly active and aggressive phagocytic macrophage, located on the epithelial lining of the lung alveoli, which ingests and destroys any inhaled particles and micro-organisms.

Amensalism (Antagonism): A type of symbiosis, wherein one population is adversely affected, while the other is unaffected.

Ames Test: A test that uses a special strain of salmonella to test chemicals for mutagenicity and carcinogenicity.

Amino Acid Activation: The first stage of synthesis of proteins, where the amino acid is attached to transfer RNA.

Amino Group: The monovalent radical NH2, attached to a carbon skeleton, as seen in amines and amino acids.

Aminoacyl or Acceptor Site (A site): The site on the ribosome that contains an aminoacyl-tRNA at the beginning of the elongation cycle during protein synthesis.

Ammonia Oxidation: A test which is conducted during manufacturing process, to evaluate ammonia oxidation rate for nitrifiers.

Ammonification: Liberation of ammonia by micro-organisms acting on organic nitrogenous compounds.

Amoeba: A minute protozoan, occurring as a single cell with a nucleus, that changes shape by extruding its cytoplasm, leading to the formation of pseudopodia, by means of which it absorbs food and moves.

Amoeboid Movement: Movement by means of extrusions of the cytoplasm, leading to formation of foot-like processes called pseudopodia.

Amphibolic Pathways: Metabolic pathways that function both anabolically, as well as catabolically.

Amphitrichous: A cell which has a single flagellum at each end.

Amphotericin B: An antibiotic derived from streptomyces nodosus which is effective against many species of fungi and certain species of leishmania.

Anaerobic: Refers to organisms that survive in the absence of oxygen (anearobic organisms), the absence of molecular oxygen, processes occurring in the absence of oxygen like anearobic respiration.

Anamorph: A stage of fungal reproduction, where cells are asexually formed by the process of mitosis.

Anaplerotic Reactions: Reactions that help replenish intermediates in the tricarboxylic acid cycle when their reserves are depleted.

Anergy: Decreased responsiveness to antigens, to the extent that there is an inability to react to substances that are expected to be antigenic.

Anion Exchange Capacity: Total exchangeable anions that a soil can adsorb. The unit used to express the amount is in centimoles of negative charge per kilogram of soil.

Annotation: The process of determining the exact location of specific genes in a genome map.

Anoxic: A condition or state which is devoid of oxygen.

Anoxygenic Photosynthesis: A type of photosynthesis where oxygen is not produced. This phenomenon is seen in green and purple bacteria.

Antagonist: A drug that binds to a hormone, neurotransmitter, or another drug, thus, blocking the action of the other substance.

Antheridium: The male gametangium found in phylum Oomycota (kingdom Stramenopila) and phylum Ascomyta (kingdom Fungi).

Anthrax: An often fatal and infectious disease, caused by ingestion or inhalation of spores of Bacillus anthracis, which are normally found in soil. It is acquired by humans through contaminated wool or animal products or by inhalation of airborne spores.

Anthropogenic: Something that is derived from human activities.

Antibiosis: Lysis of an organism brought about by metabolic products of the antagonist. This can be caused by enzymes, lytic agents, or other toxic compounds.

Antibiotic: A chemical substance produced by a microorganism, which has the capacity to inhibit the growth of, or kill other micro-organisms.

Antibody: An immunoglobulin molecule that reacts with a specific antigen that induced its synthesis and with molecules that have a similar structure.

Antibody-Dependent Cell-Mediated Cytotoxicity (ADCC): A type of reaction wherein, cells with Fc receptors that recognize the Fc region of the bound antibody and kill the antibody-coated target cells.

Anticodon Triplet: A triplet of nucleotides in transfer RNA that is complementary to the codon in messenger RNA.

Antigen: Any substance capable of instigating the immune system into action, inciting a specific immune response and reacting with the products of that response.

Antimetabolite: A substance that interferes with a specific metabolic pathway, by inhibiting a key enzyme, due to its resemblance with the normal enzyme substrate.

Antimicrobial Agent: An agent that has the capacity to kill or inhibit the growth of micro-organisms.

Antisense RNA: One of the strands of a double-stranded molecule, which does not directly encode the product, but is complementary to it, thus, inhibiting its activity.

Antiseptic: A substance that inhibits the growth and development of micro-organisms, but does not necessarily kill them.

Aplanospore: A spore that is formed during asexual reproduction, which is non-flagellated and non-motile.

Apoenzyme: A protein part of an enzyme that is separable from the prosthetic group (the coenzyme).

Apoptosis: A pattern of cell death which is often called 'programmed death' or 'suicide of cells', wherein the cell breaks up into fragments, which are membrane bound. These fragments are then eliminated by phagocytosis. This is a protective mechanism, by which the cell sacrifices itself to prevent spread of infection to other cells.

Aporepressor: A product of regulator genes, that combines with the corepressor to form the complete repressor.

Arbuscule: Special structure formed in the root cortical cells by arbuscular mycorrhizal fungi. The structure formed resembles a tree.

Artificially Acquired Passive Immunity: A type of temporary immunity that results from the introduction of antibodies produced by another organism or by in vitro methods, into the body.

Aseptic Technique: Procedures that are performed under strict sterile conditions. These procedures maybe laboratory procedures such as microbiological cultures.

Assimilatory Nitrate Reduction: Reduction of nitrate to compounds like ammonium, for the synthesis of amino acids and proteins.

Associative Dinitrogen Fixation: An enhanced rate of dinitrogen fixation, brought about by a close relationship between free-living diazotrophic organisms and a higher plant.

Associative Symbiosis: Interaction between two dissimilar organisms or biological systems, which is normally mutually beneficial.

Autogenous Infection: An infection which occurs due to the microbiota of the patient himself.

Autoimmune Disease: A disease where the target is the body's own tissues, that is, there is attacking of self-antigens.

Autoimmunity: A condition where a specific humoral or cell mediated immune response is initiated against the constituents of the body's own tissues. It normally leads to hypersensitivity reactions, and if it persists, can even escalate to an autoimmune disease.

Autolysins: A lysin that originates in an organism, which is capable of destroying its own cells and tissues.

Autoradiography: Making a radiograph of an object or tissue by recording the radiation emitted by it on a photographic plate. The radiation is emitted by radioactive material within the object or tissue.

Autotrophic Nitrification: The combined nitrification action of two autotrophic organisms, one converting ammonium to nitrite and the other oxidizing nitrite to nitrate.

Auxotroph: A mutated type of organism that requires specific organic growth factors, in addition to the carbon source present in a minimal medium.

Axenic: Pure cultures of micro-organisms, that is, which are not contaminated by any foreign organisms.

Axial Filament: Found in spirochetes, it is the organ of motility.

B
B-cell (B lymphocyte): Bursa-dependent lymphocytes which are precursors of antibody-producing cells (plasma cells) and the cells primarily responsible for humoral immunity.

B-cell Antigen Receptor (BCR): The membrane which is formed of membrane immunoglobulin or surface immunoglobulin, which allows a B-cell to detect, when a specific antigen is present in the body, and triggers B-cell activation.

Bacteria: A domain that contains prokaryotic cells that are not multicellular.

Bacteremia: Presence of bacteria in the blood.

Bacterial Artificial Chromosome: A cloning vector that is derived from E. coli, which is used to clone foreign DNA fragments in E. coli.

Bacterial Photosynthesis: A mode of metabolism, which is light-dependent and where carbon dioxide is reduced to glucose, which is used for energy production and biosynthesis. It is an anaerobic reaction.

Bactericide: A substance that kills bacteria.

Bacteriochlorophyll: A light absorbing pigment found in phototrophic bacteria, like green sulfur and purple sulfur bacteria.

Bacteriocin: Substances that are produced by bacteria which kill other strains of bacteria by inducing a metabolic block.

Bacteriorhodopsin: A protein involved in light mediated ATP synthesis, which contains retinal. It is one of the main characteristics of archaebacteria.

Bacteriostatic: An agent that inhibits the growth or multiplication of bacteria, but does not kill them.

Bacteroid: A genus of bacteroides, these are gram negative, rod-shaped, anaerobic bacteria which are normal inhabitants of the oral, respiratory, urogenital, and intestinal cavities of animals and humans.

Baeocytes: Reproductive cells formed by cyanobacteria through multiple fission. They are small and spherical in shape.

Balanced Growth: Microbial growth where all cellular constituents are synthesized at constant rates, in relation to each other.

Barophile: An organism that thrives in conditions of high hydrostatic pressure.

Barotolerant: An organism that can tolerate high hydrostatic pressure, although it will grow better under normal pressure.

Basal Body: A cylindrical structure that attaches the flagella to the cell body at the base of prokaryotic or eukaryotic organisms.

Basal Medium: A basal medium allows the growth of many types of micro-organisms which do not require special nutrient supplements.

Base Composition: The proportion of total bases consisting of 'guanine plus cytosine' or 'thymine plus adenine' base pairs.

Basidioma: Fruiting body that produces the basidia.

Basidiospore: The sexual spore of the Basidiomycotina, which is formed on the basidium.

Batch Culture: A culture of micro-organisms which is obtained by inoculating a dish containing a single batch of medium.

Batch Process: A treatment procedure wherein, a tank or reactor is filled, the solution is treated, and the tank is emptied. Batch processes are mostly used to cleanse, stabilize, or condition chemical solutions for use in industries.

Benthic Zone: The ecological region at the lowest level of a water body, including the sediment surface and some sub-surface layers.

Beta Hemolysis: A clear zone seen around a bacterial colony growing on blood agar.

Bio-Tower: A tower filled with a media similar to a rachet or plastic rings, where air and water are forced up the tower by a counterflow movement. It is an attached culture system.

Bioaccumulation: Intracellular accumulation of chemical substances in living tissue.

Bioaugmentation: Addition to the micro-organism's environment that can metabolize and grow on specific organic compounds.

Bioavailability: The extent to which a drug or other substance becomes available to the target tissue after administration.

Biochemical Oxygen Demand: The amount of dissolved oxygen consumed in five days by biological processes breaking down organic matter. It is a test that measures the oxygen consumed (in mg/L) over five days at 20 ºC.

Biodegradable: The property by which a substance is capable of being degraded by biological processes, like bacterial or enzymatic action.

Biodegradation: The process of breakdown of substances by chemical reactions, thus rendering these substances less harmful to the environment.

Bioinsecticide: A pathogen (either bacteria, virus or fungi) used to kill or inhibit the activity of unwanted insect pests.

Bioluminescence: The production of light in living organisms by the enzyme luciferase.

Biomagnification: Increase in the concentration of a chemical substance, as its position progresses in the food chain.

Biostimulation: A process which helps catalyze the activity of micro-organisms involved in biodegradation.

Biosynthesis: Production of cellular constituents from simpler compounds.

Biotransformation: The chemical alterations of a drug, occurring in the body, due to enzymatic activity.

Biotrophic: Close associations seen between two different organisms, that work mutually to benefit each other.

Bioventing: A procedure where the subsurface is aerated to enhance biological activity of naturally occurring micro-organisms in the soil.

Blastomycosis: An infection caused due to Blastomyces dermatitidis, it predominantly affects skin, lungs, and bones.

Burst size: The number of phages ejected by a host cell over the course of its lytic life cycle.

Butanediol Fermentation: A kind of fermentation found in Enterobacteriaceae family, where 2,3-Butanediol is a major product.


C
Capsid: The outer proteinaceous coat of a virus.

Capsomere: A protein sub-unit of the capsid of a virus.

Carbon Cycle: The cycle where carbon-dioxide is taken in and converted to organic compounds by photosynthesis or chemosynthesis, after which it is partially incorporated into sediments, and then returned to the atmosphere by respiration or combustion. Read more on carbon cycle steps.

Carbon Fixation: Conversion of carbon-dioxide and other single carbon compounds to organic compounds such as carbohydrates.

Carbon-Nitrogen (C/N) ratio: Ratio of carbon mass to nitrogen mass in soil or other organic material.

Carboxyl Group: The -COOH group found attached to the main carbon skeleton in certain compounds, like carboxylic acids and fatty acids.

Carboxysomes: Polyhedral cell inclusions which form the key enzyme of the Calvin cycle.

Carcinogen: An often mutated substance which is implicated as one of the causing agents of cancer.

Catabolism: A process by which complex substances are broken down into simpler compounds, often accompanied by the release of energy.

Catabolite Repression: Transcription-level inhibition of inducible enzymes by glucose, or other easily available carbon sources.

Cell-mediated Immunity: Immunity resulting from destruction of foreign organisms and infected cells by the active action of T-lymphocytes on them. It can be acquired by individuals by the transfer of cells.

Cellular Slime Molds: Slime molds with a vegetative phase containing amoeboid cells that come together to form a pseudoplasmodium.

Cellulitis: A diffused inflammation of the soft or connective tissue, in which a thin and watery exudate spreads through tissue spaces, often leading to ulceration and abscess formation.

Cephalosporin: A group of broad-spectrum, penicillinase-resistant antibiotics, derived from Cephalosporium.

Chaperonin: Heat shock proteins that oversee correct folding and assembly of polypeptides in bacteria, plasmids, eukaryotic cytosol, and mitochondria.

Chelate: A chemical compound in which a metallic ion is firmly bound into a ring within the chelating molecule. Chelates are used in metal poisoning.

Chemoautotroph: Organisms that obtain their energy from the oxidation of inorganic chemicals and other carbon compounds.

Chemoheterotroph: Organisms that obtain energy and carbon from the oxidation of organic compounds.

Chemolithotroph: Living organisms that obtain their energy from oxidation of inorganic compounds, which act as electron donors.

Chemoorganotroph: Organisms that obtain energy and electrons from the oxidation of organic compounds.

Chemostat: A continuously used culture device, controlled by limited amounts of nutrients and dilution rates.

Chemotaxis: Movement of a motile organism under the influence of a chemical. It maybe attracted towards the chemical or maybe repulsed by it.

Chemotrophs: Organisms that obtain their energy by the oxidation of chemical compounds are chemotrophs.

Chlamydospore: A thick walled intercalary or terminal asexual spore which is not shed. It is formed by rounding up of a cell.

Chronic Carrier: An individual carrying a pathogen over an extended period of time.

Chytrid: A fungus belonging to the genus Chytridomycota. It is spherical in shape and has rhizoids, which are short, thin filamentous branches, that resemble fine roots.

Cilia: Minute hairlike extensions present on a cell surface, which move in a rhythmic manner.

Ciliate: A protozoan that moves with the help of cilia.

Clarification: The process of purification of water, where suspended material in the water is removed. It can be done by using sedimentation, filtration, or by the use of adsorbing chemicals like alum.

Clone: Cells which have descended from a single parent cell. Organisms having identical copies of DNA structure, which is obtained by replication.

Colonization: Establishment of an entire community of micro-organisms at a designated site.

Colorless Sulfur Bacteria: A group of non-photosynthetic bacteria that oxidize sulfur compounds, thus deriving their energy by this process.

Combinatorial Biology: The process of transfer of genetic material from one microorganism to another. Mostly used to synthesize products such as antibiotics. It is also used in genetic engineering.

Cometabolism: Transformation of a substrate by a microorganism without deriving energy or nutrients from the substrate.

Competent: The ability to take up DNA.

Complementary DNA: A DNA copy of any RNA molecule, like mRNA or tRNA. To find out the exact difference between DNA and RNA, click here.

Complex Viruses: Viruses with capsids that are neither icosahedral nor helical. They have a complicated symmetry.

Conditional Mutations: Mutations occurring only under certain specific conditions.

Conidiospore: A thin-walled, asexual spore seen on hyphae which is not contained in sporangium.

Conjugants: Mating partners that participate in conjugation, which is a type of sexual reproduction, seen in protozoans.

Conjugative Plasmid: A self transmissible plasmid, or a plasmid that can encode all functions required to bring about its conjugation.

Consortium: Two or more members working together, where each organism benefits from the other, thus often performing functions that may not be possible to carry out individually.

Constitutive Enzyme: Enzymes synthesized in the cell, irrespective of the environmental conditions surrounding the cell.

Cosmid: A plasmid vector which can be packed in a phage capsid. It is useful for cloning large fragments of DNA.

Cyanobacterium: A photosynthetic, nitrogen fixing bacteria which includes the blue-green bacteria.

Cyst: Resting stage of certain bacteria and protozoans, wherein the entire cell is surrounded by a protective layer.

Cytokine: Non-antibody proteins released by a cell when it comes in contact with specific antigens.

Cytoplasm: The protoplasm of a cell, exclusive of the nucleus. Read more on the structure and functions of cytoplasm.

Cytoplasmic Membrane: A selectively permeable membrane which is present around the cytoplasm of the cell.


D
Decomposition: Chemical breakdown of a compound into smaller and simpler compounds by micro-organisms.

Defined Medium: A medium whose quantitative and chemical composition is exactly known.

Degradation: Process by which a compound is transformed into simpler compounds.

Denaturation: Process by which double stranded DNA unwinds into two single strands.

Denitrification: Reduction of nitrate or nitrite into simpler nitrogenous compounds like molecular nitrogen or nitrogen oxides.

Derepressible Enzyme: Enzyme produced in the absence of a specific inhibitory compound.

Dew point: The temperature to which air must be cooled to bring about the condensation of water vapor.

Diazotroph: Organism capable of using dinitrogen as its sole nitrogen source.

Differential Medium: A medium with certain indicators, which helps distinguish between different chemical reactions during growth of organisms on it.

Diffused Air Aeration: A diffused air activated sludge plant takes air, compresses it, and discharges it with force, below the surface of water.

Dikaryon: When two nuclei are present in the same hyphal compartment (they may be homokaryon or heterokaryon), it is known as dikaryon.

Dilution Plate Count Method: A method of estimating the number of viable micro-organisms in a sample.

Dinitrogen Fixation: Conversion of molecular dinitrogen into ammonia and other organic combinations useful in other biological processes.

Direct Count: Using direct microscopic examination to determine the number of micro-organisms present in a given mass of soil.

Disinfectant: An agent that kills micro-organisms.

DNA Fingerprinting: Techniques by which possible differences between different DNA samples can be assessed.

Dolipore Septum: Specialized cross-wall that separates hypha of fungi belonging to the genus Basidiomycota.

Domain: The highest level of biological classification which goes beyond kingdoms. The three domains of biological organisms are Bacteria, Eukarya, and Archaea.

Doubling Time: The time needed for a certain population to double in number.


E
Endoenzyme: Enzyme that acts along the internal portion of a polymer.

Endonuclease: The endoenzyme responsible for breaking the phosphodiester bonds in a nucleic acid molecule.

Endophyte: An organism, which may be parasitic or symbiotic, with a plant that is grown within.

Endospore: A cell which is formed by certain gram-positive bacteria in unfavorable conditions. An endospore is extremely resistant to heat and other harmful agents.

Enhanced Rhizosphere Degradation: Enhanced activity of micro-organisms involved with biodegradation of contaminants near plant roots which is brought about by compounds exuded by the plant roots.

Enrichment Culture: Technique wherein environmental conditions are altered to aid the growth of a specific organism or group of organisms.

Enteric Bacteria: These are bacteria present in the intestinal tract of humans and other animals. They may be physiologic or pathologic.

Episome: An extrachromosomal replicating genetic element found in certain bacteria.

Epitope: An antigenic determinant of known structure. It is the region of the antigen to which the variable region of the antibody binds.

Ericoid Mycorrhizae: The type of mycorrhizae found in Ericales plants. These hyphae are capable of penetrating cortical cells.

Estuaries: Water bodies located at river ends. They are subjected to tidal fluctuations.

Eubacteria: A genus of bacteria belonging to the family Propionibacteriaceae, found as saprophytes in soil and water.

Exoenzyme: An enzyme which acts outside the cell that secretes it.

Exons: The region of a split DNA that codes for RNA.

Extracellular: Outside the cell.

Exudate: A fluid high in protein and cellular debris which has escaped from blood vessels, usually as a result of inflammation.


F
Facultative Organism: An organism which is able to adjust to a particular circumstance or has the ability to take up different roles in a process.

Feedback Initiation: Inhibition by an end product of the biosynthetic pathway involved in its synthesis.

Fertilizer: Any organic or inorganic material added to the soil to enhance the growth of plants.

Field Capacity: Content of water remaining in the soil after being saturated with water.

Filamentous: In the form of very long rods, mostly seen in bacteria. Seen as branching strands in fungi.

Fimbria: Short filamentous structure present on a bacterial cell, involved with adhesion of the bacteria to other surfaces it comes in contact with.

Frustule: Siliceous wall and protoplasm seen in diatoms.

Fulvic Acid: The yellow organic material that remains behind after removal of humic acid by the process of acidification.

Fungistasis: Suppression of growth of new fungal cells, due to excessive competition for nutrients, or due to the presence of excessive inhibitory compounds in the soil.

Fungus: Eukaryotic heterotrophic organisms that live as saprophytes or parasites. This group includes mushrooms, yeast and molds. They have a rigid cell wall.

Fluorescent Antibody: This is a laboratory test that is done, wherein antibodies are tagged with fluorescent dye to detect the presence of micro-organisms.

G
Gas Vacuole: A sub-cellular organelle, found only in prokaryotes, which are gas-filled vesicles.

Gene Cloning: Isolation of a desired gene from an organism and its replication in large amounts. It is used extensively in DNA research.

Gene Probe: A strand of nucleic acid which can be labeled and hybridized to a complementary molecule from a mixture of other nucleic acids. It is helpful in DNA sequencing.

Generation Time: The time required for a population to double in number.

Genetic Code: The information on the DNA, which is required for the synthesis of proteins.

Glycosidase: The enzyme responsible for hydrolizing a glucosidic linkage between two sugar molecules.

Gram Stain: A differential stain that divides bacteria into two groups, as Gram positive and Gram negative, depending on the ability of the organism to retain crystal violet when decolorized with an organic solvent like ethanol.

Growth: An increase in the number of cells, the size, and constituents present in the cells.

Growth Factor: Organic compound essential for growth which is required in trace amounts, and which cannot be synthesized by the organism itself.

Growth Rate: The rate at which growth occurs.

Growth Rate Constant: Slope of log10 of the number of cells per unit volume plotted against time.

Growth Yield Coefficient: Quantity of carbon formed per unit of substrate carbon consumed.


H
Halophile: An organism that thrives, or at least which can survive in a saline environment.

Halotolerant: An organism that can survive in a saline environment, but does not require a saline environment for growth.

Hapten: A substance not inducing antibody formation, but which is able to combine with a specific antibody.

Heterokaryon: Hypha that contains at least two genetically dissimilar nuclei.

Heterolactic Fermentation: A kind of lactic acid fermentation, wherein various sugars are fermented into different products.

Heterothallic: Hyphae that are incompatible with each other, thus requiring another compatible hypha to mate with, to form a dikaryon or a diploid.

Heterotrophic Nitrification: The oxidation of ammonium to nitrite and nitrate by heterotrophic organisms.

Hexose Monophosphate Pathway: A metabolic pathway involving the oxidative decarboxylation of glucose:6:phosphate.

Holomictic: These are those lakes, wherein the water in them at some point of time will have a uniform temperature and density from top to bottom, thus allowing the lake waters to mix completely.

Holomorph: A fungus which consists of all sexual and asexual stages in its life cycle.

Homofermentation: A type of fermentation where there is only one type of end product generated.

Homokaryon: A fungal hypha containing nuclei which are genetically identical.

Homolactic Fermentation: A type of lactic acid fermentation, in which all sugars involved are converted into lactic acid.

Homothallic: Hyphae that are self-compatible, that is, sexual reproduction occurs in the same organism by meiosis and genetic recombination. Fusion of these hyphae lead to the formation of dikaryon or diploid.

Host: An organism that can harbor or nourish another organism.

Heterofermentation: Any fermentation where there is more than one main end product.

Humic Acid: Dark-colored organic material extracted from the soil by the use of reagents and which is precipitated by acid.

Humic Substances: High molecular weight substances formed by secondary synthesis reactions, for example, humic acid and fulvic acid.

Humification: The process of conversion of organic residues into humic substances by biochemical processes.

Hybridization: Natural or artificial construction of a duplex nucleic acid molecule by complementary base pairing between two nucleic acid strands derived from different sources.

Hydrocarbon: An organic compound containing carbon and hydrogen only.

Hydrogen Oxidizing Bacterium: These are bacteria that oxidize hydrogen for energy and synthesize carbohydrates, using carbon dioxide as their source of carbon in the absence of other organic compounds.

Hyperparasite: Parasite that feeds on another parasite.

Hyperthermophile: An organism that thrives in temperatures ranging around 80 ºCelsius or more.

Hypolimnion: This is the dense, bottom layer of water, that lies below the thermocline, in a thermally stratified lake.


I
Illuviation: Repositioning of soil removed from one horizon to another.

Immobilization: Conversion of an element from inorganic to organic form.

Immunity: The protection mechanism against infections caused by micro-organisms or toxins, that is inherent in the body.

Immunoblot: The technique for analyzing or identifying proteins via antigen-antibody specific reactions.

Immunofluoresence: The technique to determine the location of an antigen or antibody in a tissue section or smear by fluorescence.

Immunogen: A substance that has the capacity to bring about an immune response.

Immunoglobulin: A protein which has antibody activity.

In vivo: Inside the body.

Inducible Enzyme: An enzyme generated in response to an external factor.

Infection: Invasion and multiplication of micro-organisms in body tissues, leading to various diseases and disorders.

Infection Thread: The tube in root hair, through which rhizobia reach and infect roots.

Infrared (IR): The portion of the electromagnetic spectrum whose wavelength ranges from 0.75 microns to 1 millimeter.

Inoculate: To treat a medium with micro-organisms for the purpose of creating a favorable response.

Inoculum: The material used to introduce an organism into a certain medium for growth.

Insertion: A type of genetic mutation, wherein single or multiple nucleotides are added to DNA.

Insertion Sequence: The simplest possible type of transposable elements.

Integration: The process by which a DNA molecule becomes incorporated into another genome.

Interspecies Hydrogen Transfer: The process of hydrogen production and consumption reactions, occurring by the interaction of various micro-organisms.

Intracellular: Inside the cell.

Isoenzyme: When two different enzymes, which may be different in their composition, act as catalysts for the same reaction, or set of reactions.

Isolation: A procedure wherein a pure culture of an organism is obtained from a sample or an environment.

Isomorphous Substitution: The substitution of an atom by a similarly sized atom of lower valence, in a crystalline clay sheet.


J
Jaccard's Coefficient: An association coefficient of numerical taxonomy, which is the proportion of characters that match, excluding those that both organisms lack.


K
K- Strategy: Ecological strategy where organisms depend on adapting physiologically to the resources available in their immediate environment.

Koch's Postulates: Laws given by Robert Koch which prove that an organism is the causative agent of a disease.

L
Lag Phase: The time period when there is no increase in the number of micro-organisms, seen after inoculation of fresh growth medium.

Lamella: Seen in plants as the layers of protoplasmic membranes in chloroplast that contain photosynthetic pigments.

Leaching: Removal of metals from ores by the help of micro-organisms.

Lectins: Plant proteins with a high affinity for specific sugar residues.

Leghemoglobin: Red colored pigments rich in iron, which are produced in root nodules during symbiotic association between rhizobia and leguminous plants.

Ligand: A molecule, ion or group of molecules or ions, bound to the central atom by means of a chelate or coordination compound.

Light Compensation Point: The point where the rate of respiration is higher than the rate of photosynthesis, which usually occurs at about 1% of sunlight intensity.

Lime (agricultural): Soil amendment containing high levels of calcium compounds, like calcium carbonate and other such mineral which are used to neutralize soil acidity, and provide calcium for plant growth.

Lipopolysaccharide (LPS): Complex lipid structure containing sugars and fatty acids, which is commonly found in most Gram negative bacteria.

Lithotroph: An organism that uses inorganic substrate such as ammonia or hydrogen to act as electron donors in energy metabolism. They may be chemolithotrophs or photolithotrophs.

Litter: The surface layer of forests which is laden with leaves, twigs, fruits etc.

Lophotrichous: An organism that has a tuft of flagella that is polar in nature.

Luxury Uptake: Uptake of nutrients in excess of what is required by an organism for its normal growth.

Lysis: The rupture and destruction of a cell, resulting in loss of cellular contents.

Lysogeny: An association where a prokaryote contains a prophage and the virus genome is replicated in sync with the chromosome of the host.

Lysosome: A cell organelle which contains lytic enzymes.



M
Macronutrient: A substance required in large amounts for normal growth of an individual.

Macropore: Larger soil pores from which water drains readily by gravity.

Magnetosome: Small particles of magnetite, which is a compound containing magnesium, present in cells that exhibit magnetotaxis.

Magnetotactic Bacteria: Bacteria that orient themselves according to the earth's magnetic field due to the presence of the magnetosomes.

Manure: Animal excreta, with or without a bedding of litter at various stages of decomposition. It's normally considered to be a good fertilizer.

Mass Flow (nutrient): The movement of solutes in relation to the movement of water.

Medium: A source where micro-organisms are grown.

Mesofauna: Animals residing in the soil which are 200 to 1000 microns in length. This group includes nematodes, oligochaete worms, smaller insect larvae, and certain anthropods.

Mesophile: An organism that thrives in temperatures ranging from 15 - 40 ºCelsius.

Methanogenesis: The production of methane by biological reactions.

Methanogenic Bacterium: Bacteria that produce methane as a by-product of their chemical reactions.

Methanotroph: An organism capable of oxidizing methane.

Microaerophile: Micro-organisms that grow well in relatively low oxygen concentration environment.

Microaggregate: Clusters of clay stabilized by organic matter and precipitated inorganic matter.

Microbial Biomass: Total mass of micro-organisms living in a given mass or volume of soil.

Microbial Population: Total number of micro-organisms living in a given mass or volume of soil.

Microbiology: The study of micro-organisms, often with the aid of a microscope.

Microcosm: A community or any other unit that is representative of a larger community.

Microenvironment: The immediate physical and chemical surroundings of a microorganism.

Microfauna: Protozoa, nematodes, and anthropods that are smaller than 200 microns.

Microflora: This includes bacteria, virus, fungi, and algae.

Micrometer: One millionth of a meter (10-6 meters).

Micronutrient: Elements that are required for growth in trace amounts. These include copper, iron, zinc etc.

Micro-organism: An organism that is too small to be seen by the naked eye. Also called microbes, these include bacteria, fungi, protozoans, algae, and viruses.

Micropore: A small-sized soil pore (approximately less than 30 microns in diameter) which is normally found within structural aggregates.

Microsite: A small part of the soil where the biological or chemical processes are different from the rest of the soil.

Mixotroph: Organisms that are capable of assimilating organic compounds as carbon sources, while using inorganic compounds as electron donors.

Mold: A group of saprobic or parasitic fungi causing a cottony growth on organic substances.

Monoclonal Antibody: Antibody produced from a single clone of cells, which has a uniform structure and specificity.

Monokaryon: Fungal hyphae where the compartments contain only nucleus.

Morphometric Characters: These are characteristics regarding the depth, dimension, sediment distribution, water currents etc.

Motility: The ability of a cell to move from one place to another.

Mucigel: Gelatinous material found on the surface of roots growing in normal soil.

Mucilage: Gelatinous secretions and exudates produced by plant roots and most micro-organisms.

Mulch: Materials which are laid down on soil to protect it from rain, crusting, freezing etc. These materials could be sawdust, plastic, leaves etc.

Municipal Solid Waste: The total consumer and commercial waste generated in a certain confined and restricted geographic area.

Mycophagous: Organisms that eat fungi.

Mycovirus: Viruses that infect fungi.


N
Nanopore: Soil pore having dimensions in nanometers.

NAPL: A non:aqueous phase liquid which may be lighter or denser than water.

Necrotrophic: A mechanism by which an organism produces lytic enzymes that kill and then breakdown host cells for its nutrition.

Nematode: Eukaryotes that are unsegmented, usually microscopic roundworm.

Neutralism: Lack of interaction between two organisms in the same habitat.

Niche: Functional role of an organism in a certain habitat.

Nictotinamide Adenine Dinucleotide (NAD+): An important oxidized coenzyme that is a hydrogen and electron carrier in redox reactions.

Nicotinamide Adenine Dinucleotide Phosphate (NADP+): An important oxidized coenzyme that acts as a hydrogen and electron carrier in various redox reactions.

Nitrate Reduction (biological): The process of reduction of nitrate to simpler forms like ammonium by plant and micro-organisms.

Nitrification: Biological oxidation of ammonium to nitrite and nitrate.

Nitrifying Bacteria: Chemolithotrophs that can carry out the transformation from ammonia to nitrite or nitrate.

Nitrogen Cycle: The cycle where nitrogen is used by a living organism, then after the organism dies is restored to soil, followed by its final conversion to its original state of oxidation. Read more on interesting facts about nitrogen cycle.

Nitrogenase: The enzyme required for biological nitrogen fixation.

Nodulin: Proteins produced in root hair or nodules in response to rhizobial infection.

Nonpolar: A substance that is hydrophobic and does not easily dissolve in water.

Northern Blot: Hybridization of single stranded DNA or RNA to RNA fragments.

Nucleic Acid: A high molecular weight nucleotide polymer.

Nucleoid: The nuclear region of certain organisms like bacteria, which contains chromosomes, but which is not limited by a nuclear membrane.

Nucleophilic Compound: An electron donor in chemical reactions involving covalent catalysis in which the donated electrons bond with other chemical groups.


O
Oligonucleotide: A short nucleic acid chain, which is obtained from an organism or is synthesized chemically.

Oligotroph: A microorganism that has adapted itself to grow in environments that are low in nutrients.

Oospore: Thick-walled spore formed in an oogonium by fungus like organisms like the phylum Oomycota.

Operon: Genes whose expression is controlled by a single operator.


P
Parasitism: Feeding by one organism on the cells of a second, normally larger organism, thus, harming the host.

Parasexual Cycle: A nuclear cycle wherein genes of haploid nuclei recombine without meiosis.

Particle Density: Density of particles present in soil.

Particle Size: Effective diameter of a particle measured by sedimentation or micrometric methods.

Pasteurization: Process of using heat to kill or reduce the activity of micro-organisms in heat-sensitive materials.

Pathogen: An organism that is capable of causing an infection, or harming a host cell.

Pathogen Suppressive soil: Soil where a pathogen does not persist, either in its own survival or in its pathogenicity.

Pathogenicity: The ability of a parasite to infect or inflict damage on a host.

Peat: Unconsolidated soil material consisting mostly of undecomposed organic matter with excessive moisture content.

Pellicle: A rigid protein layer just below the cell membrane.

Peptidoglycan: Rigid cell wall layer seen in bacteria. It's also called murein.

Peribacteroid Membrane: A plant derived membrane which surrounds rhizobia in host cells of legume nodules.

Periplasmic space: The area between the cell membrane and cell wall in Gram negative bacteria.

Perithecium: Flask shaped ascocarp open at the tip.

Peritrichous Flagellation: Multiple flagella present all over the cell surface.

Permanent Wilting Point: The highest concentration of soil at which plants present in it, will irreversibly wilt when placed in a humid chamber.

Phosphobacterium: Bacteria that are good at dissolving insoluble inorganic phosphate that is present in the soil.

Photoautotroph: Self-sufficient organisms that can generate energy from light and carbon dioxide.

Photoheterotroph: Organisms able to use light as a source of energy and organic materials as carbon source.

Photophosphorylation: Synthesis of high energy phosphate bonds by the use of light as a source of energy.

Phototaxis: Movement of an organism, or a part of it, towards light.

Phytoextraction: The use of plants or algae for removing contaminants from soil, sediments, or water, and turning them into harvestable plant biomass.

Phycobilin: Water-soluble pigment that is seen in cyanobacteria and is the light harvesting pigment for Photosystem II.

Pilus: Fimbria like substance present on fertile cells that deals with transfer of DNA during the process of conjugation.

Plaque: A localized area of lysis or cell inhibition which is caused due to virus infection.

Plasmogamy: Fusion of two cell contents, inclusive of the cytoplasm and nuclei.

Plate Count: Number of colonies formed on a solid culture medium, when uniformly inoculated with a known amount of soil.

Polar Flagellation: The presence of flagella at one or both ends.

Protoplast: A cell devoid of cell wall.

Pour Plate: The method of performing a plate count of micro-organisms.

Psychrotroph: An organism that is able to grow at zero degrees and above twenty degrees Celsius.

Pure Culture: A microorganism population of a single strain.


R
Radioimmunoassay: An immunological assay that makes use of radioactive antibodies or antigens to detect certain substances.

Reaction Center: A photosynthetic complex containing chlorophyll and other compounds.

Reannealing: The process seen on cooling, where two complementary strands of DNA hybridize back into a single strand.

Recalcitrant: Resistance of an organism to a microbial attack.

Recombination: Process by which genetic elements in two separate genomes are brought together in one unit. This is an important step in gene therapy.

Replication: Conversion of one double stranded DNA molecule into two identical double stranded DNA molecules.

Repression: Process by which an enzyme synthesis is suppressed due to the presence of certain external substances.

Reverse Transcription: Process of copying information from RNA to DNA.

Rhizobacteria: Bacteria that are found in roots, where they aggressively colonize.

Rhizobia: Bacteria capable of living symbiotically in leguminous plant roots, from where they receive energy and commonly fix molecular dinitrogen.

Rhizomorph: Mass of fungal hyphae that are organized in long, thick strands with a darkly pigmented outer rind that contains specialized tissues for absorption and water transport.

Rhizoplane: Plant root surface and strongly adhering soil particles.

Rhizosphere: The zone of soil immediately adjacent to plant roots in which the activity and type of micro-organisms present differ from that in the rest of the soil.

Rhizosphere Competence: Ability of an organism to colonize the rhizosphere.


S
Sanitization: Elimination of pathogenic or harmful organisms, including insect larvae, intestinal parasites, and weed seeds.

Sclerotium: Modified fungal hyphae that form a compact and hard vegetative resting structure with a thick pigmented outer rind.

Secondary Metabolite: Product of intermediary metabolism released from a cell, for example, antibiotic.

Selective Medium: A medium that is biased in allowing only certain types of micro-organisms to grow.

Serial Dilution: Series of stepwise dilutions, normally done in sterile water, which is done to reduce microorganism populations to manageable numbers.

Serology: Study of reactions that take place between antigens and antibodies in vitro.

Sheath: Tubular structure that is found either around a chain of cells or around a bundle of filaments.

Siderochromes: The compounds that are synthesized by the micro-organisms themselves, which are responsible for iron uptake.

Siderophore: A metabolite that is formed by some micro-organisms, that forms a strong coordination compound with iron.

Slime Layer: A diffuse layer found immediately outside the cell wall in certain bacteria.

Slime Mold: Micro-organisms that are eukaryotic and which lack cell walls.

Solarization: A technique to control the growth of pathogens, wherein a plastic sheet is used to cover moistened soil in hot climates, thereby trapping the incoming radiation.

Specific Activity: Expressed as micromoles formed per unit time per milligram of protein, this is the amount of enzyme activity units per mass of protein.

Spermosphere: The area seen around a germinating seed, where there is increased microbiological activity.

Spread Plate: A technique for performing a plate count of micro-organisms.

Sterilization: The process whereby an object or surface is rendered free of any living micro-organisms.

Storage Polysaccharide: The energy reserves which are stored in a cell when there is excess of carbon available.

Strain: Population of cells, all of which arise from a single pure isolate.

Substrate: A base on which an organism is grown. They can also be the substances on which compounds and enzymes act.

Sulfur Cycle: The cycle wherein sulfur, the element is taken up by living organisms, then released upon the death of the organism, and then converted to its final state of oxidation.

Symbiosis: Two dissimilar organisms, living together. Their association maybe commensal or mutualistic.

Synergism: Association between two organisms that is mutually beneficial.

Syntrophy: Interaction between two or more populations that supply each other's nutritional needs.

Systemic: Something that involves the entire body and is not localized in the body.


T
Teichoic Acids: All wall, membrane, or capsular polymers containing glycerophosphate or ribitol phosphate residues.

Telemorph: One of the stages of sexual reproduction, wherein cells are formed by meiosis and genetic recombination.

Temperate Virus: A virus that does not cause destruction and lysis of the cells of its host, but instead, its genome may replicate in sync with that of the host.

Terminal Electron Acceptor: The last acceptor of the electron, as it exits the electron transport chain.

Thermocline: That point in a lake, where there is a drastic drop in temperature with increase in depth.

Thermophile: An organism that grows best at temperatures around 45 and 80 ºCelsius.

Ti plasmid: A conjugative tumor inducing plasmid that can transfer genes into plants. Seen in the bacterium Agrobacterium tunefaciens.

Toxin: A foreign substance present in the body, which is mostly generated by micro-organisms, that is capable of inflicting damage on the host cell.

Transduction: The process where host genetic information is transferred through an agent like a virus or a bacteriophage.

Transgenic: Genetically modified plants or organisms, which contain foreign genes, which have been inserted by means of recombinant DNA techniques.

Transposable Element: A genetic element that can be transposed from one site on a chromosome to another.

Transposon: Transposable element which, in addition to transposable genes, carries other genes.

Transposon Mutagenesis: A mutant phenotype is formed by inactivation of the host gene, which occurs due to the insertion of a transposon.

Tricarboxylic Acid Cycle: A series of metabolic reactions, by which pyruvate is oxidized to carbon dioxide.

Trophic Level: Describes the residence of nutrients in various organisms along a food chain ranging from the primary nutrient assimilating autotrophs to carnivorous animals.


U
Uronic Acid: A class of acidic compounds that contain both carboxylic and aldehydic groups and are oxidation products of sugars. They occur mainly in polysaccharides.


V
Vadose Zone: Unsaturated zone of soil which is above the groundwater, extending from the bottom of the capillary fringe to the soil surface.

Vector: An agent that can carry pathogens from one host to another. It can also denote a plasmid or virus used in genetic engineering to insert genes into a cell.

Vegetative Cell: A growing or actively feeding form of a cell, as against a spore.

Vesicles: Spherical structures formed intra-cellularly, by certain arbuscular mycorrhizal fungi.

Viable but Nonculturable: Living organisms that cannot be cultured on artificial media.

Viable Count: Measurement of the concentration of live cells in a microbial population.

Vibrio: Curved, rod-shaped bacteria that cause cholera, belonging to the genus Vibrio.

Virion: The virus particle and the virus nucleic acid surrounded by a protein coat.

Virulence: The degree of pathogenicity of a parasite.


W
Water Content: The amount of water contained in a material, which is expressed as the mass of water per unit mass of oven:dry material.

Water Retention Curve: A graph showing soil water content as a function of increasingly negative soil water potential.

White Rot Fungus: Fungus that attacks lignin, along with cellulose and hemicellulose, leading to marked lightening of the infected wood.

Wild Type: Strain of a microorganism that is isolated from nature. The native and original form of a gene or organism.

Winogradsky Column: A glass column that allows growth of micro-organisms under conditions similar to those found in nutrient-rich water and sediments. This column contains an anaerobic lower zone and an aerobic upper zone.

Woronin Body: A spherical structure found in fungi belonging to the phylum Ascomycota, which are associated with the simple pore in the septa separating the hyphal compartments.

X
Xenobiotic: A compound that is foreign to the biological systems.

Xerophile: An organism that is capable of growing at low water potentials, that is, in very dry habitats.


Z
Zymogenous Flora: Refers to micro-organisms that respond rapidly by enzyme production and growth when simple organic substrates become available.
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