Published in the Bulletin of Experimental Treatments for AIDS April 1999 issue, by the San Francisco AIDS Foundation.

April 1999 Table of Contents

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Glossary

A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X-Z

A

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.

ANEMIA: reduced ability of blood to carry oxygen due to a low hemoglobin level, or an abnormality or reduced number of red blood cells.

ANGINA: chest pain caused by reduced flow of blood to the heart muscle.

ANGIOMATOSIS: a tumor composed of blood or lymph vessel tissue.

ANTENATAL: the period of time before birth.

ANTIBODY (IMMUNOGLOBULIN): a protein secreted by activated plasma cells, which evolve from B-cells, in response to stimulation by an antigen.

ANTIGEN: any agent or substance (e.g., microorganisms or the substances they produce) that stimulates an immune response.

APOPTOSIS: programmed cell death.

AREA UNDER THE CURVE (AUC): a measure of drug concentration.

ASPERGILLOSIS: an uncommon life-threatening infection caused by the fungus Aspergillus.

ASSAY: a test, especially one used to detect the presence and/or concentration of a component, drug, or microorganism in the blood or other body fluids or tissues.

AS-TREATED ANALYSIS: a method of analyzing the results of a clinical trial in which only participants who successfully complete a course of treatment are analyzed.

ATHEROSCLEROSIS: "hardening of the arteries" in which cholesterol and other deposits build up on the inner walls of the arteries, limiting the flow of blood.

B

B-CELL (B-LYMPHOCYTE): an immune system cell that carries out the humoral immune response. B-cells are produced in the bone marrow and mature into plasma cells that produce antibodies.

BILIRUBIN: a yellow pigment released when red blood cells are broken down. High blood bilirubin levels are characterized by jaundice, a yellowing of the skin and eyes, and may indicate liver disease.

BIOAVAILABILITY: the extent to which a drug is absorbed and circulated in the body.

BLINDING: a method of conducting clinical trials so that some or all of the participants do not know whether subjects are taking active drug or placebo. Blinding is done to reduce bias in drug trials. See also double-blind.

BLOOD-BRAIN BARRIER: a set of physical barriers between the blood vessels and the brain that allows only certain substances to pass through.

BONE MARROW: the soft, spongy tissue in the interior of certain bones that contains stem cells and is the site of blood cell production.

BRANCHED-CHAIN DNA ASSAY (bDNA): a test for measuring the amount of virus (viral load) in blood plasma or tissue.

BREAKTHROUGH: a condition that develops despite measures to prevent it (e.g., PCP that occurs while taking a prophylactic drug). Also, a rise in viral load after it has fallen due to anti-HIV therapy (virological breakthrough).

C

CANDIDIASIS: a disease caused by the fungus Candida.

CARCINOMA: a malignant tumor of the epithelial cells that line body surfaces and cavities.

CCR5: a protein found on certain cells that acts as a receptor for chemokines and as a co-receptor that enables HIV to enter cells.

CD4 CELL (CD4 LYMPHOCYTE, HELPER T-CELL): a white blood cell that carries the CD4 cell surface receptor and helps the body fight infection.

CD8 CELL (CD8 LYMPHOCYTE): a white blood cell that helps regulate and/or carry out the body's immune response. There are two major subsets: suppressor T-cells and cytotoxic T-lymphocytes (CTL).

CELL-MEDIATED IMMUNITY (CELLULAR IMMUNITY, TH1 RESPONSE): the immune response mediated by the Th1 subset of CD4 cells. Cell-mediated immunity is carried out by cytotoxic T-lymphocytes and macrophages.

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

CEREBROSPINAL FLUID (CSF): a clear, nutrient-rich fluid that circulates around and through the brain and spinal cord.

CERVIX (adjective CERVICAL): the cylindrical, lower part of the uterus leading into the vagina.

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

CHEMOKINE: a soluble factor secreted by certain immune system cells that stimulates the activity of other cells.

CHEMOTHERAPY (adjective CHEMOTHERAPEUTIC): the use of chemicals or drugs to treat disease; the term is typically used to refer to cancer treatment.

CHLAMYDIASIS (CHLAMYDIA): an infection, usually sexually transmitted, with the bacteria Chlamydia trachomatis. Chlamydiasis is the most common sexually transmitted disease in the U.S.

CHOLESTEROL: a fatty substance in animal tissue that is an essential component of cell membranes and nerve fiber insulation. 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 against heart disease.

CHROMOSOME: a structure of compact, intertwined molecules of DNA found in the nucleus of cells which carry the cell's genetic information. Humans normally have 46 chromosomes.

COHORT: a group of individuals in a study who share a demographic, clinical, or other statistical characteristic (e.g., age, study site).

COLPOSCOPY (BIOMICROSCOPY): examination of the tissues of the uterine cervix or anal canal using a low-powered, lighted microscope (colposcope) to identify abnormal cell growth and, if necessary, remove a tissue sample for biopsy.

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

CO-RECEPTOR: a second cell surface receptor required for entry by a pathogen into a host cell or initiation of a biological process.

CORTISOL: a steroid hormone secreted by the adrenal cortex as part of the body's response to stress.

C-PEPTIDE: a protein fragment produced in the formation of insulin.

CREATININE: a protein in muscles and blood; a metabolic waste product of muscle activity eliminated in the urine. High creatinine levels may indicate kidney damage or muscle disease.

CROSS-RESISTANCE: the development of resistance to one agent (e.g., drug) which also confers resistance to another (often similar) agent.

CUSHING'S SYNDROME: a disorder caused by excessive secretion of the adrenal gland hormone cortisol. The syndrome is characterized by accumulation of fat around the abdomen and the upper back.

CUTANEOUS: relating to the skin.

CXCR4: a co-receptor on the surface of certain T-cells that, along with the CD4 receptor, allows HIV to infect the cell.

CYTOCHROME P450 (CP450) SYSTEM: a system that metabolizes drugs and other foreign substances in the liver by means of enzymes (e.g., CYP3A4) that inhibit or promote metabolic reactions.

CYTOKINE: an intercellular chemical messenger protein (e.g., tumor necrosis factor, interleukin) released by white blood cells. Cytokines facilitate communication among immune system cells.

CYTOMEGALOVIRUS (CMV, HHV-5): a herpesvirus that may cause retinitis, pneumonia, colitis, and/or encephalitis in immunocompromised people.

CYTOTOXIC T-LYMPHOCYTE (CTL, KILLER T-CELL): an immune system white blood cell that targets and kills cells infected with microorganisms.

D

DENDRITIC CELL: a type of immune system cell with many branches. Dendritic cells are found in the skin and mucosal membranes.

DESENSITIZATION: the reduction of sensitivity to a drug by administering a small amount and gradually increasing the dose.

DIABETES MELLITUS: a disease caused by insufficient insulin production or lack of responsiveness to insulin, resulting in hyperglycemia (high blood glucose levels).

DISSEMINATION: spread of a disease-causing organism throughout the body, possibly causing symptoms at multiple sites.

DNA (DEOXYRIBONUCLEIC ACID): a molecule found in the nucleus of cells that encodes genetic information.

DORSOCERVICAL FAT PAD ("BUFFALO HUMP"): an accumulation of fatty tissue at the base of the neck.

DOSAGE REGIMEN: a formalized schedule by which drugs are administered, including the amount of drug, the number of doses in a period of time, and the time between doses.

DOUBLE-BLIND: a type of clinical trial in which neither the subject nor the investigator knows what treatment, if any, the subject is receiving.

DYSPEPSIA: indigestion or "upset stomach."

DYSPLASIA: the abnormal development or growth of cells and tissues; precancerous tissue changes.

E

ENCEPHALITIS: inflammation of the brain.

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

ENTERIC: a medicinal preparation that passes through the stomach intact and disintegrates in the intestines.

ENV: the gene of HIV that encodes the proteins that make up its outer envelope.

ENVELOPE: the outer covering of certain types of viruses.

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

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

EPITHELIUM: a thin layer of cells that covers the internal and external surfaces of the body, including body cavities, ducts, and vessels. The epithelium includes squamous epithelial cells and columnar epithelial cells, which meet and overlap at transition zones.

ESCHERICHIA COLI (E. COLI): a strain of intestinal bacteria; a frequent cause of urogenital infections.

ESOPHAGITIS: inflammation of the esophagus (swallowing tube); symptoms may include "heartburn" and painful or difficult swallowing.

F

FIRST-LINE TREATMENT: the preferred standard therapy for a condition.

FOLLICLE: a small sac or pore. Hair follicles are depressions in the skin from which hair shafts grow; ovarian follicles are the site of ovum (egg) production.

FORESKIN: a fold of skin covering the head of the penis; sometimes removed by circumcision.

FUSION INHIBITOR: a drug (e.g., T-20) that inhibits the binding of HIV's envelope to a host cell's receptors.

G

GAG: the gene of HIV that encodes the core proteins of the virus.

GASTROINTESTINAL: relating to the stomach and intestines.

GENE (adjective GENETIC): the unit of heredity. A gene contains hereditary information encoded in the form of DNA and is located at a specific position on a chromosome in a cell's nucleus.

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

GENOME: the unique genetic code or hereditary material of an organism.

GENOTYPE (adjective GENOTYPIC): the specific genetic makeup or "blueprint" of an organism. Genotypic resistance testing determines whether an organism's genetic structure contains certain mutations that make it resistant to a drug.

GESTATION: pregnancy.

GLUCOSE (BLOOD SUGAR): a form of sugar that is the body's primary fuel; glucose broken down from food can be converted into energy or stored. Abnormally low or high levels of glucose in the blood often indicate metabolic disturbances (e.g., diabetes).

GONORRHEA: a sexually transmitted disease caused by the bacteria Neisseria gonorrhoeae.

H

HAART: highly active antiretroviral therapy, a term for potent combination anti-HIV treatment that usually includes a protease inhibitor drug.

HALF-LIFE: the time required for half of the amount of an agent (e.g., drug, virus) to be eliminated from the body.

HEMOPHILIA (person HEMOPHILIAC): a hereditary disease that prevents normal blood clotting, leading to easy bruising and potentially severe hemorrhage.

HEPATITIS: an inflammation of the liver that may be caused by several agents, including viruses, toxins, and drugs. Acute hepatitis is typically characterized by fever, jaundice, fatigue, abdominal tenderness, and elevated liver enzymes.

HEPATITIS A (HAV, INFECTIOUS HEPATITIS): an inflammatory viral disease of the liver with a short incubation period. Hepatitis A virus (HAV) may be transmitted by eating contaminated food, by fecal-oral contact, and/or through household contact. Hepatitis A may be mild to severe; symptoms include fever, nausea, and jaundice. An anti-HAV vaccine is available.

HEPATITIS B (HBV, SERUM HEPATITIS): a viral liver disease that may be acute or chronic, and can be life-threatening.

HEPATOMEGALY: liver enlargement.

HERPESVIRUS: a group of viruses that includes herpes simplex virus types 1 and 2, varicella-zoster virus, Epstein-Barr virus, cytomegalovirus, human herpesvirus types 6 and 7, and Kaposi's sarcoma-associated herpesvirus (HHV-8).

HERPES ZOSTER (SHINGLES): a condition characterized by painful blisters that typically appear in a linear distribution on the skin following nerve pathways. Shingles is caused by reactivation of a previous infection with the varicella-zoster virus.

HORMONE: a chemical messenger involved in the regulation and coordination of cellular and bodily functions.

HUMAN PAPILLOMAVIRUS (HPV): a papovavirus. Many strains of HPV cause warts, including condylomata acuminata (genital warts). Certain strains (e.g.,16, 18) are associated with cervical and anal cancer.

HUMORAL IMMUNITY (TH2 RESPONSE): the immune response mediated by the Th2 subset of CD4 cells. Humoral immunity is stimulated by cytokines including IL-4 and IL-6, and carried out by plasma cells (derived from B-cells) which produce antibodies.

HYPERCHOLESTEREMIA: a high level of cholesterol in the blood.

HYPERCORTISOLEMIA: a high level of cortisol in the blood.

HYPERGLYCEMIA: high blood sugar.

HYPERLIPIDEMIA: elevated levels of blood fats (e.g., triglycerides, cholesterol).

HYPERSENSITIVITY REACTION: an exaggerated immune response to an antigen, drug, etc.

HYPERTENSION: high blood pressure.

HYPERTRIGLYCERIDEMIA: an elevated level of triglycerides (fatty acid compounds) in the blood.

HYPERTROPHY: excessive growth; enlargement.

I

IMMUNE SYSTEM: the body's defense system that protects against foreign invaders (e.g., microorganisms) and cancerous cells. Immune system organs include the lymph nodes, spleen, thymus, and tonsils.

IMMUNOGLOBULIN: see antibody.

IMMUNOLOGY (adjective IMMUNOLOGIC): the study and/or treatment of disorders that involve the immune system (e.g., cancer, HIV disease, autoimmune diseases).

IMMUNOSUPPRESSION: reduced function of the immune system; a state in which the immune system defenses have been suppressed, damaged, or weakened.

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

INCIDENCE: the number of new cases of a disease or condition in a specific population during a given period of time.

INDUCTION: the initiation phase of a particular therapy.

INFUSION: the direct injection of a substance into the bloodstream.

INSULIN: a peptide hormone produced in the pancreas. Insulin enables the body to metabolize and use glucose. Lack of or insensitivity to insulin results in diabetes.

INTENT-TO-TREAT ANALYSIS: a method of analyzing the results of a clinical trials in which all participant originally assigned to an arm are analyzed, including those who dropped out due to treatment failure or side effects.

INTERFERON: a cytokine (chemical messenger) that play a role in immune response.

INTERFERON-ALPHA (IFN-ALPHA, INTRON-A, ROFERON-A): a type of interferon produced in response to viral infection. Genetically engineered interferon-alpha is used to treat Kaposi's sarcoma, anogenital warts, and chronic hepatitis B and C, and is under study as an anti-HIV therapy. Side effects include flu-like symptoms, anemia, and neutropenia.

INTERLEUKIN (IL): a cytokine secreted by immune system blood cells that regulates a range of immune functions. IL-2 is produced by activated CD4 cells and promotes the proliferation and activity of T-cells and natural killer cells.

INTRAEPITHELIAL: within or among the cells of the tissues that cover body surfaces and line cavities, ducts, and vessels.

INTRAPARTUM: during birth.

INTRAVENOUS (IV): injected directly into a vein.

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

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

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

ISOLATE: a specific individual microbe and its genetically identical progeny.

J

JAUNDICE: a yellowish discoloration of the skin and whites of the eyes due to high bilirubin levels resulting from the breakdown of red blood cells; jaundice is associated with liver damage.

K

KAPOSI'S SARCOMA (KS): an abnormal or cancerous proliferation of cells of the blood and/or lymph vessels causing tumors on the skin, mucous membranes, and/or internal organs. KS typically appears as pink or purple, flat, or raised lesions.

KIDNEY STONE (NEPHROLITHIASIS): an accumulation of substances (e.g., drug crystals, minerals) in the kidney, which may lead to blockage and pain.

L

LANGERHANS CELL: a type of dendritic cell in the skin and mucous membranes that transports antigens to the lymph nodes.

LAVAGE: the washing out of an organ or cavity to obtain a sample for diagnosis.

LESION: any abnormal tissue change caused by disease or injury.

LEUKOCYTE: a white blood cell (e.g., monocyte, neutrophil, B-cell, T-cell). White blood cells are involved in the body's defense against infections and cancer.

LIMIT OF quantification: the lower boundary of an assay (e.g., a viral load test). The limit of detection is the level below which a test cannot measure the presence of a component (e.g., HIV RNA).

LIPASE: a digestive enzyme produced by the pancreas that helps to break down large fatty molecules (e.g., triglycerides) into smaller constituent molecules.

LIPID: a fat.

LIPODYSTROPHY: loss of fatty tissue, usually in the limbs and face. The term is sometimes used to refer to any type of body fat redistribution.

LIVER ENZYME: a protein produced by the liver (e.g., ALT, AST) that catalyzes various physiological reactions. Abnormally high blood levels may indicate liver damage.

LOG: refers to quantities in factors of ten. A log change is an exponential or ten-fold increase or decrease (e.g., going from ten to 100 is a one-log increase).

LONGITUDINAL: refers to a study that occurs over an extended period of time.

LUTEAL PHASE: the stage in the menstrual cycle characterized by the presence of the corpus luteum, a yellowish mass of progesterone-secreting tissue.

LYMPH NODES: small, bean-sized organs located throughout the body. Lymph nodes filter out antigens and are the site of immune cell activation.

LYMPHOCYTE: a type of white blood cell (T-cell, B-cell, natural killer cell) that plays a part in immune defense.

M

MACROPHAGE: a large scavenger white blood cell that ingests and processes degenerated cells and foreign invaders.

MAINTENANCE THERAPY: preventive therapy that follows successful initial treatment of an illness.

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

MEMORY CELL: a B-cell or T-cell that is specialized to respond to a specific pathogen and remains in the body after an initial immune response. Memory cells are primed to respond to a subsequent attack by the same invader in the future.

MENINGITIS: an inflammation of the meninges, the membranes that envelop the brain and spinal cord.

METABOLISM (adjective METABOLIC): the process of building the body's molecular structures from nutrients (anabolism) and breaking them down for energy production (catabolism).

MICROBICIDE: an agent that inactivates, kills, or destroys microbes. Vaginal and anal microbicides are under study as a means of preventing HIV transmission.

MONOCYTE: a large white blood cell that plays a role in immune defense. When monocytes leave the bloodstream and migrate to the tissues they become macrophages.

MONOTHERAPY: the use of a single drug or other therapy.

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

MUTANT: a new organism produced by a change in the character of a gene.

MUTATION: a change in the character of a gene that is perpetuated when a cell divides or a virus replicates. A mutant is a new organism produced by a genetic mutation.

MYCOBACTERIUM AVIUM COMPLEX (MAC): an opportunistic disease caused by Mycobacterium avium or Mycobacterium intracellulare, bacteria found in soil and water.

N

NADIR: the lowest point. The term is used to refer to the lowest CD4 T-cell count a person ever reached before the count increased due to anti-HIV treatment.

NAIVE: inexperienced; used to describe an individual who has never taken a given treatment (e.g., antiretroviral-naive)

NAIVE CELL: an undifferentiated immune system cell (e.g., naive CD4 T-cell) that has not yet specialized to recognize a specific pathogen.

NECROSIS: localized tissue death.

NEF: a gene of HIV that influences viral replication.

NEOPLASIA: an abnormal cell growth that may progress to cancer.

NEPHROLITHIASIS: see kidney stone.

NEUTROPENIA: an abnormally low blood level of neutrophils, an immune system white blood cell that engulfs and destroys bacteria and fungi.

NEUTROPHIL: a white blood cell that engulfs and destroys bacteria and fungi.

NON-HODGKIN'S LYMPHOMA (NHL): a type of cancer of the lymph nodes. NHL is characterized by abnormal growth of B-cells, and is the most common type of lymphoma in people with HIV/AIDS.

NON-NUCLEOSIDE REVERSE TRANSCRIPTASE INHIBITOR (NNRTI): a drug (e.g., delavirdine, nevirapine, efavirenz) that binds to and inhibits the action of the HIV reverse transcriptase enzyme, thus blocking viral transcription and replication.

NUCLEOSIDE: a precursor compound that is a converted into a building block of genetic material (DNA or RNA) by the addition of a phosphate group.

NUCLEOSIDE ANALOG (also known as NUCLEOSIDE REVERSE TRANSCRIPTASE INHIBITOR, NRTI): a compound (e.g., AZT, ddI, ddC, d4T, 3TC, abacavir) that mimics one of the building blocks of DNA. These compounds suppress retroviral replication by interfering with the reverse transcriptase enzyme.

NUCLEOTIDE: one of the building blocks that make up DNA and RNA.

O

OCTOXYNOL: a surfactant chemical used as a spermicide and microbicide.

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

OPEN-LABEL: a drug trial in which both participants and investigators know what drug is being tested and what dosages are being used.

P

PANCREATITIS: inflammation of the pancreas, a digestive gland in the abdominal cavity. Symptoms may include abdominal pain, nausea, constipation, and jaundice.

PAP SMEAR: a procedure in which a specimen of cells is taken from the uterine cervix or anus, prepared on a slide, and examined under a microscope.

PATHOGEN: any disease-causing agent, especially a microorganism.

PATHOGENESIS: the origin and development of a particular disease, including the specific events involved, bodily tissues or systems affected, and mechanisms of damage.

PCR: see polymerase chain reaction.

PERINATAL HIV TRANSMISSION (VERTICAL TRANSMISSION): the transmission of HIV from mother to child. Perinatal transmission may occur in utero (in the womb), intrapartum (during birth), or postpartum (after birth, via breast-feeding).

PERIPHERAL NEUROPATHY: damage to the peripheral nerves (usually involving the feet and hands) characterized by pain or numbness.

PH: a logarithmic scale used to describe the acidity or alkalinity of a solution; a measure of the hydrogen concentration of a solution. Water has a neutral pH of 7. A pH below 7 is acidic; a pH above 7 is alkaline (or basic).

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

PHENOTYPE (adjective PHENOTYPIC): visible characteristics and/or behavior that result from the interaction of an organism's genotype and the environment.

PLACEBO: an inert, inactive substance; a "sugar pill." Experimental therapies are compared to placebo in many clinical trials.

PLACEBO-CONTROLLED TRIAL: a trial of an experimental therapy in which an inactive substance or mock therapy (placebo) is given to one group while the treatment being tested is given to another, and the results are compared.

PLAQUE: an expansion of the inner surface of a blood vessel resulting from lipid deposits.

PLASMA: the fluid, non-cellular portion of blood.

PLATELET: see thrombocyte.

PNEUMOCYSTIS CARINII PNEUMONIA (PCP): a life-threatening opportunistic type of pneumonia caused by a protozoan.

POL: the HIV gene that encodes the virus' replicative enzymes (protease, integrase, reverse transcriptase); also the protein produced by that gene.

POLYMERASE: an enzyme that cleaves polymers, chemical compounds formed by the linkage of molecular pieces.

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

POST-EXPOSURE PROPHYLAXIS (PEP): drug therapy given immediately following exposure to an infectious organism in an attempt to prevent the infection from taking hold in the body.

POSTPARTUM: the period following childbirth.

PREVALENCE: the number of individuals with a condition in a specific population.

PRIMARY HIV INFECTION (PHI): the initial introduction of HIV into the body; the earliest stage of HIV disease.

PRODROME: a set of symptoms or signs that indicate the onset of a disease.

PROLIFERATION: rapid reproduction or replication.

PROPHYLAXIS (adjective PROPHYLACTIC): therapy that helps to prevent a disease before it occurs (primary prophylaxis) or recurs (secondary prophylaxis).

PROSPECTIVE STUDY: a study that looks forward in time. Participants are selected and their progression is followed over time.

PROSTATE GLAND: a large gland in males located at the base of the urethra that manufactures the liquid portion of semen.

PROTEASE: an enzyme that cuts proteins; HIV protease allows replication of the virus.

PROTEASE INHIBITOR: a drug (e.g., amprenavir) that blocks the action of the HIV protease enzyme to prevent viral replication.

PROTOCOL: a plan that states the specifics of a clinical trial, such as the hypothesis to be tested, drug(s) to be used, method(s) of administration, length of the trial, endpoints to be used, and characteristics of participants (e.g., inclusion/exclusion criteria).

PROVIRUS: a state in which viral DNA has been inserted into the chromosomes of the host cell.

R

RANDOMIZED TRIAL: an experiment arranged so as to produce a chance distribution of subjects into different treatment groups or arms.

REAGIN: a substance in the blood of persons with syphilis responsible for positive serological reactions for syphilis.

RECEPTOR: a specific protein-binding site on a cell's surface or interior. Viruses enter cells by fusing with receptors on a cell's surface.

RECOMBINANT: produced by genetic engineering.

REFRACTORY: resistant to treatment.

REGIMEN: see dosage regimen.

REMISSION: an abatement in the severity of disease symptoms.

REPLICATION: multiplication or reproduction.

RESERVOIR: a site where an infectious agent collects and multiplies; macrophages and resting CD4 cells are thought to be reservoirs of HIV.

RESISTANCE: the mutation of a microorganism in such a way that it loses its sensitivity to a drug.

RETINITIS: inflammation of the retina, the light-sensitive tissue at the back of the eyeball, that may lead to the loss of vision.

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

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

REVERSE TRANSCRIPTASE (RT): a viral enzyme that allows a retrovirus to translate its genetic material (in the form of RNA) into DNA, which is then integrated into the chromosomes of the host cell.

REVERSE TRANSCRIPTASE INHIBITOR (RTI): a drug that blocks retroviral replication by interfering with the reverse transcriptase enzyme. RTIs include nucleoside analogs (e.g., AZT, ddI, 3TC, abacavir) and non-nucleoside reverse transcriptase inhibitors (e.g., nevirapine, delavirdine, efavirenz).

RNA (RIBONUCLEIC ACID): a single-stranded nucleic acid made up of nucleotides. Messenger RNA (mRNA) is involved in the transcription of genetic information and the production of new proteins.

S

SAFER SEX: sexual activities that reduce or eliminate the exchange of body fluids that can transmit HIV (e.g., semen, vaginal, or cervical fluid), often by means of barriers (e.g., latex condoms, gloves, dental dams).

SALVAGE THERAPY: treatment with experimental or non-standard drugs for an illness that has not responded to standard therapy.

SEMEN: a whitish, viscid fluid that contains spermatozoa and is ejaculated from the penis.

SEPSIS: a life-threatening blood infection characterized by low blood pressure.

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

SERUM: the fluid, non-cellular portion of blood that remains after coagulation; lymphatic fluid.

SEXUALLY TRANSMITTED DISEASE (STD): a disease (e.g., gonorrhea, syphilis, herpes, chlamydiasis) that is transmitted through sexual contact.

SHEDDING: the release of infectious particles (e.g., bacteria, viruses) into the environment, for example by sneezing, by fecal excretion, or from an open lesion.

SIDE EFFECT: an unwanted adverse reaction to a drug treatment (e.g., rash, nausea, peripheral neuropathy, bone marrow suppression, liver failure).

SIMIAN IMMUNODEFICIENCY VIRUS (SIV): a viral infection endemic to African green monkeys and able to infect various primates. SIV is similar to HIV-2.

SQUAMOUS CELL: a flat, thin cell that comprises the surface of the skin and the linings of the esophagus, vagina, and rectum.

STATISTICAL SIGNIFICANCE: the probability that an observed outcome of an experiment or trial is not due to chance alone.

STEM CELL: a precursor cell in the bone marrow from which all blood cells derive.

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

STRAIN: a specific genetic variant of an organism.

SUBCUTANEOUS: under the skin.

SUSCEPTIBLE: refers to a microorganism that is vulnerable to the effects of a drug.

SYMPTOMATIC: showing outward signs of a disease.

SYNCYTIUM (plural SYNCYTIA): a clump of cells whose membranes have fused to form a "giant cell."

SYNERGY: the action of two or more drugs working together to produce an effect greater than the expected combined effect of the same agents used separately.

SYPHILIS: a sexually transmitted infectious disease caused by the spirochete bacterium Treponema pallidum.

SYSTEMIC: affecting the whole body; not localized.

T

T-CELL (T-LYMPHOCYTE): a type of white blood cell that matures in the thymus and carries out the cell-mediated immune response. There are three major types of T-cells: helper (CD4) T-cells, suppressor (CD8) T-cells, and killer T-cells (cytotoxic T-lymphocytes, or CTL).

THROMBOCYTE (PLATELET): a type of blood cell that facilitates normal blood clotting.

THRUSH: candidiasis (fungal infection) of the mouth.

THYMUS: an immune system organ in the upper chest where T-cells mature.

TITER (TITRE): a standard measure of the strength or concentration of a component per volume of a solution.

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

TOXOPLASMOSIS: an opportunistic infection caused by the microscopic protozoan Toxoplasma gondii. A common manifestation of the disease is toxoplasmic encephalitis, an infection of the brain.

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

TRIGLYCERIDE: a combination of glycerol and fatty acid that circulates in the blood.

TROUGH LEVEL: the lowest concentration of a drug reached in the body between dosages.

TRUNCAL OBESITY ("PROTEASE PAUNCH"): an accumulation of fat in the abdominal area.

TUBERCULOSIS (TB): an infectious disease caused by Mycobacterium tuberculosis that typically affects the lungs (pulmonary TB), but may also occur in other organs (extrapulmonary TB). TB infection refers to asymptomatic, latent infection with TB bacteria; active TB disease refers to symptoms caused by replicating bacteria.

TUMOR NECROSIS FACTOR (TNF, CACHECTIN): a cytokine, produced by activated monocytes and macrophages, that can destroy tumors. When chronically elevated (as may occur in HIV disease), TNF-alpha may lead to fever, anorexia, hypermetabolism, and wasting. TNF-alpha may block the production of enzymes that digest fats, leading to the breakdown of muscle tissue. In laboratory tests TNF-alpha has been shown to stimulate HIV replication.

U

ULCER (ULCERATION): an open sore on the skin or mucous membrane characterized by sloughing of inflamed dead tissue.

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

URETHRA: the canal that carries urine from the bladder to the outside of the body.

V

VACCINE: a preparation that contains an infectious agent or its components which is administered to stimulate an immune response that will protect a person from illness due to that agent. Agents used in vaccines may be whole killed (inactivated) organisms, live-attenuated (weakened) organisms, or artificially manufactured pieces of an organism.

VARICELLA-ZOSTER VIRUS (VZV, HHV-3): a herpesvirus that initially causes chickenpox and may reactivate later to cause herpes zoster (shingles).

VASODILATION: dilation of the blood vessels.

VERTICAL TRANSMISSION (PERINATAL TRANSMISSION, MATERNAL-FETAL TRANSMISSION): transmission from a mother to a fetus or newborn. Vertical transmission may occur in utero (in the womb), intrapartum (during birth), or postpartum (after birth, via breast-feeding). Contrast with horizontal transmission.

VIRAL LOAD: the amount of virus in the blood or other tissues. The presence of HIV RNA indicates that the virus is replicating.

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

VIRION: a complete virus particle.

VIROLOGICAL FAILURE: an increase in viral load after it has been suppressed with antiretroviral drugs.

VISCERA (adjective VISCERAL): the major internal organs of the body (e.g., intestines, liver) located in the abdominal cavity.

W

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

WASTING SYNDROME: a condition characterized by atrophy of lean body mass and involuntary weight loss of more than 10% of normal body weight.

WESTERN BLOT: a laboratory blood test for HIV antibodies.

WILD-TYPE: the normal, typical form of a virus before genetic mutation takes place.

WINDOW PERIOD: the time between primary infection and the appearance of antibodies against an organism (seroconversion).

Page last updated 1 June 1999