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

Year-End 1999 Table of Contents

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Glossary

Compiled by Nicholas Cheonis

AMINO ACID: an organic compound that is a basic structural unit of peptides and proteins.

AMNIOTIC FLUID: the fluid contained within the amnion, or innermost membrane of the uterus, that envelops the fetus during pregnancy.

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

ANTIBODY (AB, IMMUNOGLOBULIN, IG): an immunoglobulin protein secreted by activated plasma cells, which evolve from B-cells. Antibodies are produced in response to stimulation by foreign antigens as part of the body's defense against disease.

ANTIEMESIS (adjective ANTIEMETIC): the relief of nausea and vomiting.

ANTIRETROVIRAL: an agent (e.g., AZT, ddI, nevirapine) that suppresses the activity or replication of retroviruses such as HIV.

ANTISENSE: a complementary piece of genetic material (DNA or RNA) that binds to another piece of DNA or RNA by base-pairing, which prevents that DNA/RNA fragment from being used to synthesize new proteins.

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.

BASELINE: an initial or known value (e.g., CD4 cell count, HIV viral load) against which later measurements can be compared.

B-CELL (B-LYMPHOCYTE): an immune system white blood cell that carries out the humoral (TH2) immune response. B-cells are produced in the bone marrow and mature into plasma cells that produce antibodies. B-cells are influenced by various cytokines (chemical messengers) as well as interactions with T-cells and other immune system components. Contrast with T-cell.

BETA BLOCKER: one of a large group of medications that obstruct specific nervous system receptors, causing a deceleration of the heart rate, a reduction in blood pressure, and reduced anxiety.

BIOPSY: the removal of a small sample of cells or tissue for microscopic examination and/or culture.

BODY MASS INDEX (BMI): a measure of mass that is calculated as weight divided by height squared.

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

CD4 CELL (CD4 LYMPHOCYTE, T-HELPER CELL, T4 CELL): a type of white blood cell that carries the CD4 cell surface receptor and helps the body fight infection. CD4 cells release cytokines (chemical messengers) that coordinate a broad range of immune system activities including killer cell activation and antibody production.

CD8 CELL (CD8 LYMPHOCYTE, T8 CELL): a type of white blood cell that carries the CD8 cell surface marker and helps regulate and/or carry out the body's immune response. Two subsets of T-cells express the CD8 surface marker: T-suppressor cells and cytotoxic T-lymphocytes (CTLs).

CERVICOVAGINAL: relating to the uterine cervix and the vagina, parts of the female reproductive system.

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. Chemokines have chemoattractant properties and act as messengers between cells.

CHOLESTEROL: a fatty substance in animal tissue that is an essential component of cell membranes and nerve fiber insulation. See also low-density lipoprotein.

CHRONIC: persisting or recurring over a long period of time; marked by slowly progressing seriousness.

CIRRHOSIS: a condition in which the liver becomes scarred, fibrous, and filled with fat, thus reducing its ability to function.

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

COLLAGEN: a fibrous protein that makes up connective tissue.

CORRELATES OF IMMUNITY (CORRELATES OF PROTECTION): the specific immune responses that render protection from a certain infection.

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

CYTOKINE: an intercellular hormone or chemical messenger protein (e.g., tumor necrosis factor, interleukin) released by white blood cells (e.g., macrophages, T-cells). Cytokines facilitate communication among immune system cells and between immune system cells and the rest of the body.

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

DEOXYRIBONUCLEIC ACID (DNA): a molecule that encodes genetic information and is found in the nucleus of cells as a twisted double-stranded chain. See also ribonucleic acid.

DIALYSIS: a procedure for cleansing the blood using membranes to filter out waste elements. Kidney dialysis is used to substitute for the function of damaged or absent kidneys.

DIURETIC: an agent that increases the amount of urine excreted.

DNA: see deoxyribonucleic acid.

ELISA: see enzyme-linked immunosorbent assay.

ENDOSCOPY (adjective ENDOSCOPIC): 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.

ENV: the gene of HIV that encodes the proteins of the viral envelope; also refers to the proteins produced by that gene.

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

ENZYME-LINKED IMMUNOSORBENT ASSAY (ELISA): a laboratory test used to detect the presence of antibodies in the serum. ELISA is used for first-line screening for HIV antibodies; a positive result indicates that antibodies have been detected. The test is sensitive but not specific, and a positive ELISA is typically confirmed using a Western blot assay.

FIBROSIS: the development of fibrous tissue.

FIRST-LINE TREATMENT: the preferred standard therapy for a particular condition. FUNGUS (plural FUNGI): a class of organisms that includes yeasts, molds, and mushrooms, several of which can cause disease (mycosis) in humans (e.g., candidiasis, cryptococcosis, histoplasmosis).

GAG: the gene of HIV that encodes the core proteins of the virus; also refers to the proteins produced by that gene.

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. Genes determine many aspects of anatomy and physiology by controlling the production of proteins.

GENOME (adjective GENOMIC): the unique genetic code or hereditary material of an organism, carried by a set of chromosomes in the nucleus of each cell.

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. Contrast with phenotype.

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).

GLYCOPROTEIN (GP): a small unit made up of a sugar and a protein molecule, often part of a cell's membrane. Glycoproteins make up the envelope of HIV (e.g., gp120, gp160 [numbers denote molecular weight]).

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

HELICASE: an enzyme that unwinds the DNA helix into single strands, thereby facilitating replication.

HEMOGLOBIN: the red, iron-based pigment in red blood cells that enables them to transport oxygen. Normal hemoglobin values are 12-15 grams per deciliter (100 milliliters) for women and 14-16 grams per deciliter for men.

HEPATIC: relating to the liver.

HEPATITIS: an inflammation of the liver that may be caused by several agents, including viruses, toxins, or drugs. Acute hepatitis is typically characterized by fever, jaundice, fatigue, abdominal tenderness, and elevated liver enzymes. Hepatitis A causes an inflammatory viral disease with a short incubation period. Hepatitis B and C can become chronic and may result in liver damage, cirrhosis, or liver cancer.

IMMUNE SYSTEM: the body's defense system that protects against foreign invaders (e.g., microorganisms) and cancerous cells. Types of immune defense include cell-mediated (TH1) and humoral (antibody-based, or TH2). Immune system organs include the lymph nodes, spleen, thymus, and tonsils.

IMMUNITY: resistance to disease; the body's ability to recognize and defend against pathogenic organisms and cancerous cells. Immunity may be either natural or acquired (i.e., artificially induced), long-lasting or temporary, partial or complete, specific or nonspecific.

IMMUNIZATION: the process by which a person is protected against the adverse effects of infection by a disease-causing microorganism. Active immunization (vaccination) involves inoculating a person with an antigen and relying on their body to mount an immune response.

IMMUNOMODULATOR (IMMUNE MODULATOR): an agent or process capable of modifying or influencing the functions of the immune system. Immune modulators include cytokines (e.g., IL-2, gamma interferon) and broad-acting agents. See also immunotherapy.

IMMUNOTHERAPY (IMMUNE-BASED THERAPY): a therapy that attempts to modify or enhance immune response, or reconstitute a damaged immune system. Examples of immune-based therapies for HIV disease include active immunization (vaccination), passive hyperimmune therapy, CD8 cell line expansion, and cytokine therapy. See also immunomodulator.

INCUBATION PERIOD: the period of time between an initial exposure to an infectious agent and the development of symptoms of disease, during which the infection is established in the body.

INOCULATION: the introduction of a pathogen or antigen into the body, especially to stimulate antibody production or other immune responses.

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 the body of a living organism." Refers to studies done using human or animal subjects.

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 purplish or brownish lesions.

LACTIC ACIDOSIS: a buildup of lactic acid (a byproduct of carbohydrate metabolism) in bodily tissues.

LEUKOCYTE: an immune system 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.

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

LOG: refers to quantities in factors of ten. A log change is an exponential or ten-fold increase or decrease (e.g., a change from ten to 100 is a 1-log increase).

LOW-DENSITY LIPOPROTEIN (LDL): a type of cholesterol in the body; also known as "bad" cholesterol. LDL is considered a risk factor for heart disease.

LUPUS: see systemic lupus erythematosus.

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

MACROPHAGE: a large scavenger white blood cell that ingests and processes degenerated cells and foreign invaders. Macrophages are reservoirs of HIV.

MASTITIS: inflammation of the breast, usually caused by infection.

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.

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

MONOTHERAPY: use of a single drug or other therapy.

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

NEF: a gene of HIV that influences viral replication and may help HIV evade host defenses; also refers to the protein produced by that gene.

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

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

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

NUCLEOTIDE (DEOXYRIBONUCLEOTIDE, RIBONUCLEOTIDE): one of the building blocks that make up genetic material (DNA and RNA). Nucleotides consist of a base (adenine, cytosine, guanine, thymine, or uracil), a sugar, and a phosphate group.

OPPORTUNISTIC INFECTION (OI): a disease caused by a microorganism that does not normally cause illness in a person with a healthy immune system, but that may cause serious disease when the immune system is weakened. Common OIs in HIV positive people include Pneumocystis carinii pneumonia (PCP), Mycobacterium avium complex (MAC), and cytomegalovirus (CMV) infection.

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

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

PERINATAL TRANSMISSION: see vertical transmission.

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 genetic "blueprint" (genotype) and the environment. Phenotypic resistance testing determines whether an organism is susceptible to a specific drug in a test tube. Contrast with genotype.

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

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

PLASMA: the fluid, noncellular portion of blood.

PLATELET: see thrombocyte.

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

POLYMER: a chemical compound formed by the linkage of molecular pieces.

POLYMERASE: an enzyme that cleaves polymers.

PRIMARY ISOLATE: HIV taken from an infected individual, as opposed to that grown in a laboratory.

PRODRUG: an inactive form of a drug that exerts its effects after metabolic processes within the body convert it to a usable or active form.

PROLIFERATION: rapid reproduction or replication.

PROTEASE INHIBITOR: a drug (e.g., saquinavir, ritonavir, indinavir, nelfinavir, amprenavir) that blocks the action of the HIV protease enzyme, thereby preventing viral replication. Unlike reverse transcriptase inhibitors, protease inhibitors can inhibit HIV replication in cells that are already infected.

QUASISPECIES: a substrain of an organism that develops within an individual by the process of evolutionary selection.

RECOMBINANT: produced by genetic engineering.

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

RIBONUCLEIC ACID (RNA): a single-stranded nucleic acid that encodes genetic information. RNA is made up of a sequence of four chemical building blocks (nucleotides)-adenine, cytosine, guanine, and uracil. RNA is involved in the transcription of genetic information; the information encoded in DNA is translated into messenger RNA (mRNA), which controls the synthesis of new proteins. The presence of HIV RNA in the plasma indicates that the virus is actively replicating.

RNA: see ribonucleic acid.

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

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

SYNERGY (SYNERGISM, adjective SYNERGISTIC): an interaction between agents (e.g., drugs) that produces an effect greater than the combined effects of the same agents used separately.

SYSTEMIC: affecting the whole body.

SYSTEMIC LUPUS ERYTHEMATOSUS: an autoimmune disease of unknown cause characterized by inflammation of the connective tissue, especially in the joints.

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

THROMBOCYTE (PLATELET): a disk-shaped blood cell that facilitates blood coagulation and the repair of blood vessels.

THYMUS (adjective THYMIC): a lymphoid organ located in the chest behind the sternum. The thymus is a source of T-cell production in the fetus and the site of T-cell maturation and differentiation, i.e., where the cells learn to recognize antigens.

TMP-SMX: see trimethoprim-sulfamethoxazole.

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.

TRIMETHOPRIM-SULFAMETHOXAZOLE (TMP-SMX, BACTRIM, SEPTRA): an antibiotic drug combination. TMP-SMX is the preferred first-line therapy for prophylaxis and treatment of PCP, and may be effective against other OIs such as toxoplasmosis.

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. In laboratory tests, TNF-alpha has been shown to stimulate HIV replication.

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

VACCINE: a preparation containing an infectious agent or its components that is administered to stimulate an immune response that will protect a person from illness due to that agent.

VASCULAR: relating to or containing blood or lymph vessels.

VECTOR: an agent used as a vehicle for transfer. A viral vector is an engineered virus used to introduce genes into cells, or a live virus used as an antigen delivery vehicle in a vaccine.

VERTICAL TRANSMISSION (PERINATAL TRANSMISSION, MATERNAL-FETAL TRANSMISSION): transmission of a pathogen such as HIV 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).

VIRAL LOAD (VIRAL BURDEN): the amount of virus in the blood or body tissues.

VIREMIA: the presence of virus in the blood.

VIRION: a complete virus particle.

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

VIRUS: any of a large group of minute organisms that cannot grow or reproduce outside a host cell. During replication, a virus integrates its genetic material (DNA or RNA) into the host cell and takes over the cell's biological mechanisms to reproduce new viral particles.

WHITE BLOOD CELL (WBC): see leukocyte.

WHOLE-KILLED VIRUS: a type of vaccine in which a complete, inactivated virus is used to provoke an immune response.

WIHS: Women's Interagency HIV Study, a longitudinal study of HIV disease in women.

WILD TYPE: the normal, typical phenotype of a virus or other organism before genetic mutation takes place.

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

WORLD HEALTH ORGANIZATION (WHO): an organization of the United Nations concerned with worldwide public health.

Page last updated 8 January 2000