Published in the Bulletin of Experimental Treatments for AIDS April 1998 issue, by the San Francisco AIDS Foundation.

April 1998 Table of Contents

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Glossary

Compiled by Liz Highleyman

ACUPUNCTURE: a technique from traditional Chinese medicine that involves inserting very thin needles into different acupuncture points (meridians) on the body to improve the flow of qi, the body's vital energy.

ACUTE RETROVIRAL SYNDROME (ARS): a combination of flu-like symptoms (e.g., fever, sore throat, skin rash, headache, nausea, muscle or joint pain) that occurs during or shortly after primary HIV infection.

ADRENAL GLAND: an organ located above each kidney that produces hormones including adrenaline, cortisol and certain androgens.

ADVERSE EVENT: an unwanted toxic reaction or side effect of drug treatment.

AIDS DRUG ASSISTANCE PROGRAM (ADAP): a state program that provides drugs for HIV/AIDS and related opportunistic infections to individuals who otherwise could not afford them.

ALKALINE PHOSPHATASE: an enzyme found in various body tissues and fluids. A high alkaline phosphatase level suggests liver damage.

AMYLASE: an enzyme produced by the salivary glands and the pancreas that helps break down food. An abnormal increase in serum amylase levels may indicate inflammation of the pancreas (pancreatitis).

ANAPHYLAXIS (ANAPHYLACTIC SHOCK): a life-threatening allergic reaction to a foreign antigen.

ANEMIA: an abnormally low number of red blood cells or a decreased concentration of hemoglobin, resulting in reduced oxygen transport to cells and tissues.

ANGIOGENESIS: the growth and proliferation of blood vessels.

ANOREXIA: the lack or loss of appetite for food.

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

ANTIEMETIC: a drug that relieves nausea and vomiting.

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

ANTIGEN-PRESENTING CELL: a cell (e.g., dendritic cell, macrophage) that processes antigen proteins and displays short peptide fragments on its surface for recognition by T-cells.

ANTIHELMINTHIC: a drug used to treat infestation with helminths (e.g., round worms, flat worms and tape worms).

ANTIOXIDANT: a substance that inhibits an oxidation reaction by binding with and neutralizing free radicals and other highly reactive molecules, thus reducing oxidative damage.

ANTIRETROVIRAL: an agent that suppresses the activity or replication of retroviruses such as HIV.

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

APHTHOUS ULCER: a small often painful shallow lesion on the mucous membranes lining the mouth, esophagus or rectum.

APOPTOSIS: programmed cell death.

ARRHYTHMIA: loss of normal heart rhythm.

ARTHRALGIA: pain in a joint.

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

ATTENUATE: to weaken or reduce the level of virulence. An attenuated virus has a diminished ability to cause disease, and may be used in vaccines.

AUTOIMMUNE RESPONSE: a condition (e.g., rheumatoid arthritis, systemic lupus erythematosus) in which an individual's immune system attacks its won bodily tissues as if they were foreign matter.

AYURVEDIC: a system of traditional medicine practiced in India.

B-CELL (B-LYMPHOCYTE): an immune system 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.

BILIRUBIN: a yellowish pigment released by red blood cells when they are removed from circulation and broken down. An excess level of serum bilirubin is characterized by jaundice and may indicate stress on the liver.

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

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 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.

BUFFALO HUMP: an accumulation of fatty tissue at the base of the neck that may be a side effect of certain anti-HIV drugs.

CACHEXIA: body wasting.

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

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

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.

CHEMOKINE: a type of cytokine, a soluble factor secreted by certain immune system cells that stimulates the activity of other cells. Certain chemokine receptors (e.g., CCR5, CXCR4) are necessary for entry by HIV into cells.

CHINESE MEDICINE: an Asian system of healing that focuses on achieving internal balance. Practitioners use methods such as acupuncture, heat application (moxibustion), herbal preparations, food therapy, massage and exercise (Qi Gong or Tai Chi) to restore the flow of Qi (vital energy) and the balance of Yin and Yang.

CHOLESTEROL: a fatty substance in animal tissue that is an essential component of cell membranes and nerve fiber insulation. There are 2 types of cholesterol in the blood, high-density lipoprotein (HDL) and low-density lipoprotein (LDL).

CHRONIC: slow, persisting over a long period.

CLINICAL TRIAL: an organized procedure for determining the effectiveness of a new drug or therapy by administering the agent to participants under strictly controlled conditions.

COLOSTRUM: breast fluid, produced prior to milk production, that contains antibodies.

COMPLEMENTARY AND ALTERNATIVE MEDICINE (CAM): any type of therapy not considered standard practice in a given culture. In most Western countries, CAM includes traditional Chinese medicine, homeopathy, naturopathy and chiropractic. Complementary therapy is typically used as an adjunct to standard therapy, while alternative medicine is used instead of standard therapy.

CORE: the internal portion of a viral particle.

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

CORTICOSTEROID: a steroid produced by the adrenal cortex. Corticosteroids have anti-inflammatory and immunosuppressive properties, and are used to treat a variety of conditions.

CREATININE: a protein in muscles and blood; a metabolic waste product of muscle activity that is 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.

CRYPTOCOCCOSIS: an infection caused by a fungus, typically Cryptococcus neoformans, found in soil and bird feces.

CRYPTOSPORIDIOSIS: a disease caused by the protozoan Cryptosporidium parvum, which is most commonly transmitted to humans by contact with animal feces, ingestion of contaminated food or water, or oral-anal sexual contact.

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

CYTOCHROME P450 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 and between immune system cells and the rest of the body.

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

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

DENDRITIC CELL: a type of immune system cell. Dendritic cells are found in the skin and mucous membranes and arrive early at sites of injury or infection, where they bind to invaders and transport them to the lymph nodes.

DESENSITIZATION: the reduction of sensitivity to an antigen or a drug, typically achieved by administering a small amount and gradually increasing the dose.

DESQUAMATION: shedding or peeling of the outer layer of the skin.

DNA (DEOXYRIBONUCLEIC ACID): a molecule found in the nucleus of cells that encodes genetic information. The particular sequence of 4 chemical building blocks (nucleotides) determines an individual's unique genetic code.

DOSE ESCALATION: the gradual increase of drug dosages to determine the amount that delivers the best balance of high efficacy and acceptable side effects.

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

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

EFFICACY: effectiveness.

ENCEPHALITIS: an inflammation of the brain.

ENCEPHALOPATHY: any disease 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).

ENVELOPE: the outer covering of some viruses.

EPITHELIUM: a thin layer of cells that covers the internal and external surfaces of the body, including body cavities, ducts and vessels.

EXFOLIATION: detachment and shedding of the outer layers of skin or mucous membrane.

EXPANDED ACCESS: an FDA program that allows distribution of experimental drugs to people with life-threatening illness who have failed or cannot tolerate approved therapies, are unable to participate in clinical trials and have no other treatment options.

FLATULENCE: excessive intestinal gas.

FORMULARY: a list of approved or available drugs.

FUNDOSCOPY: examination of the interior of the eye with an instrument that allows the examiner to see through the pupil. Fundus photography is a method of diagnosing eye disease.

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

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.

GLUCOSE (BLOOD SUGAR): a form of sugar that is the body's primary fuel. Abnormally low or high glucose levels in the blood indicate metabolic disturbances (e.g., diabetes).

HAART: highly active antiretroviral therapy, a term for aggressive anti-HIV treatment usually including a protease inhibitor drug.

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 virus (HAV) causes an inflammatory viral disease with a short incubation period. Hepatitis B and C virus can become chronic and may result in liver damage, cirrhosis and/or liver cancer.

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.

HOMEOPATHY: a treatment methodology that uses extremely small, diluted doses of substances that normally cause the types of symptoms one is seeking to treat.

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.

HYBRIDIZATION: the fusion of 2 or more components to create a hybrid, an entity that is related to, but different from, its parts. An offspring produced by blending the genetic material of 2 or more different strains of an organism.

HYDROXYUREA: an agent that interferes with viral replication by inhibiting the host cell enzyme ribonucleotide reductase, resulting in a reduction of the supply of the building blocks needed to make new DNA.

HYPERGLYCEMIA: high blood sugar (glucose) level.

HYPERSENSITIVITY: abnormal sensitivity; an exaggerated immune response to an antigen, drug, etc.

IATROGENIC: refers to an unfavorable response to medical or surgical treatment, or symptoms attributable to a medical therapy.

IMMUNE SYSTEM: the body's defense system that protects against foreign invaders (e.g., microorganisms) and cancerous cells. There are 2 branches: cell-mediated (Th1) and humoral (antibody-based or Th2). Organs of the immune system include the lymph nodes, spleen, thymus, tonsils and bone marrow.

IMMUNIZATION: a process by which a person is protected against the adverse effects of infection by a disease-causing microorganism by exposing the person to a small amount of the killed or inactivated organism or to pieces of the organism.

IMMUNOCOMPROMISE: reduction in immune system function.

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

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.

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

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 in the flanks, back or groin.

LEPROSY: a disease caused by Mycobacterium leprae, characterized by skin lesions and necrosis.

LEUKOPENIA: abnormally low number of white blood cells in the circulating blood.

LIMIT OF DETECTION: 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).

LIPODYSTROPHY: changes in body shape typically characterized by loss of fatty tissue in the limbs and face and redistribution of fat to the trunk, abdomen or back of the neck.

LIVER FUNCTION TEST: a blood test that measures levels of liver enzymes (e.g., AST, ALT) to indicate how well the liver is working and whether it might be inflamed or damaged.

LOG: refers to quantities in factors of 10. A log change is an exponential or 10-fold increase or decrease (e.g., going from 10 to 100 is a 1-log increase).

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

LYMPHOCYTE: a type of white blood cell (e.g., T-cell, B-cell) responsible for immune defense.

MACROPHAGE: a large scavenger white blood cell that ingests degenerated cells and foreign particles and secretes messenger proteins involved in a variety of immune system responses.

MENINGITIS: an inflammation of the meninges, the membranes that envelope 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.

MICROSPORIDIOSIS: infection with a protozoan parasite of the Microsporidia family (e.g., Enterocytozoon bieneusi, Septata intestinalis) which may affect the sinuses, lungs and intestines of immunocompromised patients.

MONOCLONAL ANTIBODIES: antibodies derived from a single clone of cells and directed against a particular antigen.

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

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

MYALGIA: pain in the muscles.

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

MYOPATHY: inflammation or degeneration of the muscles that may cause pain or weakness.

NAIVE: inexperienced. The term is used to describe an individual who has never taken a certain drug (e.g., AZT-naive), or to refer to undifferentiated immune system cells.

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

NECROSIS: localized tissue death.

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

NEOPLASM: a tumor or growth; tissue that develops abnormally or grows more rapidly than normal and lacks structural organization and functional coordination with normal tissue.

NEUTROPENIA: an abnormally low number of neutrophils, a type of white blood cell involved in defense against bacteria and fungi.

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 ANALOG (NA): 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; the synthetic nucleosides cause premature termination of the proviral DNA chain.

NUCLEOTIDE: a building block of genetic material (DNA and RNA). Nucleotides consist of a base (adenine, cytosine, guanine, thymine or uracil), a sugar and a phosphate group.

OLIGONUCLEOTIDE: a short sequence of nucleotides.

OLIGOSACCHARIDE: a compound made up of a short chain of sugar molecules.

OOCYST: the earliest stage of the life cycle of a parasitic protozoan (e.g., cryptosporidium) during which it is enclosed in a hard-shelled protective capsule.

OPPORTUNISTIC INFECTION (OI): a disease (e.g., PCP, MAC, CMV disease) caused by a microorganism that does not normally cause illness in a person with a healthy immune system, but which may cause serious disease when the immune system is suppressed.

p24 ANTIGEN: a protein fragment of HIV; a positive p24 antigen test indicates that HIV is actively replicating and predicts disease progression.

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

PARESTHESIA: an abnormal physical sensation such as prickling, tingling or numbness with no apparent external stimuli.

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, mechanisms of damage and timing of the course of disease.

PERINATAL HIV TRANSMISSION (PHT, 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: a disorder of the peripheral nerves, usually involving the feet, hands and sometimes the legs, arms and face. Symptoms may include numbness, tingling or burning sensations, pain, abnormal reflexes, weakness and partial paralysis.

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 responds to a specific drug.

PHYTOPHARMACEUTICAL: a plant or plant product used as a drug.

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 obtained in the different groups are compared.

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

PLASMID: a piece of genetic material that is not part of a chromosome. Genetically engineered plasmids are often used in biotechnology.

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

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 samples.

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

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.

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

PROGRESSIVE MULTIFOCAL LEUKOENCEPHALOPATHY (PML): a rapidly progressing, often fatal brain disease believed to be caused by the JC papovavirus. PML infects oligodendrocytes (support cells in the brain) and leads to deterioration of the brain's white matter. Symptoms include headache, changes in mental status, speech and vision difficulties, limb weakness, seizures, loss of coordination and paralysis.

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

PROTEASE INHIBITOR: a drug (e.g., saquinavir, indinavir, ritonavir, nelfinavir, amprenavir) that blocks the action of the HIV protease enzyme, thereby preventing viral replication.

PROTEASE: an enzyme that cleaves proteins, allowing HIV replication.

"PROTEASE PAUNCH": accumulation of fatty tissue around the midsection that may be a side effect of protease inhibitor drugs.

PRURITUS (adjective PRURITIC): itchiness.

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

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.

REMISSION: an abatement in the severity of disease symptoms; a period of time during which symptoms are reduced or eliminated.

REPLICATION: duplication or reproduction.

RESERVOIR: a site where an infectious agent collects and multiplies (e.g., macrophages and lymph nodes are thought to be HIV reservoirs).

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

RETINAL DETACHMENT: a condition in which a layer of the retina separates from the underlying epithelium, allowing vitreous fluid to seep behind it. The condition may lead to loss of vision.

RETINITIS: inflammation of the retina, the light-sensitive tissue at the back of the eyeball that transmits visual impulses to the brain.

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.

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. RTI include nucleoside analogs (e.g., AZT, ddI, 3TC) and non-nucleoside reverse transcriptase inhibitors (e.g., nevirapine, efavirenz).

REYE'S SYNDROME: a life-threatening condition involving brain inflammation and vomiting that may occur in children and adolescents following an illness with fever.

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.

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

SEDATIVE: a drug that reduces mental activity and excitement and/or induces sleep.

SENSITIVITY: the ability of an organism to be affected by a drug.

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.

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

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

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

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

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

STEVENS-JOHNSON SYNDROME: an unusual, life-threatening reaction characterized by fever and flu-like symptoms followed by a severe, blistering rash on the skin and/or mucous membranes. Stevens-Johnson syndrome may occur as a reaction to certain drugs.

STRAIN: a specific genetic variant of an organism.

SUBTYPE: a distinct form of a microorganism.

SUBUNIT: a piece or small part of a larger unit. Subunit HIV vaccines are vaccines that contain a piece of HIV.

SULFA DRUG: a sulfonamide-containing antibiotic drug.

SYNERGY: the action of 2 or more drugs working together to produce an effect greater than the expected combined effect of the same agents used separately.

SYSTEMIC: affecting the whole body; not localized.

T-CELL (T-LYMPHOCYTE): a type of white blood cell derived from the thymus that participates in a variety of cell-mediated immune responses. There are 3 major types of T-cells: T-helper (CD4), T-suppressor (CD8) and T-killer (cytotoxic T-lymphocytes or CTL).

TERATOGENICITY: the ability to cause malformation of the fetus (birth defects).

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

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 is toxoplasmic encephalitis, characterized by brain swelling, confusion, lethargy, seizures and coma.

TRICHOMONIASIS: infection with the sexually transmitted parasite Trichomonas vaginalis. Symptoms in women may include vaginal irritation, itching, discharge and painful urination.

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

TUMOR NECROSIS FACTOR ALPHA (TNF-ALPHA, CACHECTIN): a cytokine produced by activated monocytes and macrophages that can destroy tumors.

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

URTICARIA (HIVES): itchy, raised, swollen areas on the skin or mucous membranes, often a sign of an allergic reaction.

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. A therapeutic vaccine is given after infection and is intended to reduce or arrest disease progression. A preventive vaccine is intended to prevent initial infection.

VESICLE: a small, fluid-filled blister on the skin.

VIRAL LOAD: the amount of virus in the blood or other tissues. The presence of HIV RNA indicates that the virus is replicating. Changes in viral load may be used to gauge drug effectiveness and disease progression. Viral load is measured using assays such as the RT-PCR or branched-chain DNA (bDNA) tests.

VIREMIA: the presence of virus in the blood or plasma.

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

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

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

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

ZINC FINGER INHIBITOR: a type of anti-HIV drug that binds to a protein involved in the transcription of DNA to RNA.

Page last updated 5 May 1998