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Published in the Bulletin of Experimental Treatments for AIDS June 1997 issue, by the San Francisco AIDS Foundation. |
GlossaryCompiled by Liz Highleyman A ACCELERATED APPROVAL: FDA regulations governing early marketing approval of promising drugs for life-threatening illnesses. ACUPUNCTURE: a Traditional Chinese Medicine technique that involves inserting very thin needles into different acupuncture points (meridians) on the body to improve the flow of qi (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 accompanies primary HIV infection or occurs shortly after infection. ALLOPATHY (adjective ALLOPATHIC): "Western medicine." Therapeutic system in which illness or disease is treated by producing a second condition that is antagonistic toward or incompatible with the first. ALTERNATIVE THERAPY: therapy that is not considered standard practice in most Western countries, e.g., Traditional Chinese Medicine, homeopathy. AMEBA: a type of protozoan, especially Entamoeba histolytica, that invades the bowel mucosa, often causing diarrhea. ANALGESIC: a drug or therapy that reduces perception of or sensibility to pain. ANAPHYLAXIS: a life-threatening allergic reaction to a foreign antigen characterized by swelling, difficulty breathing and a decrease in blood pressure. ANABOLIC STEROID: a hormone (e.g., testosterone, oxandrolone) that promotes the synthesis of proteins and the building of muscle mass. ANDROGEN: a hormone (e.g., testosterone, androsterone) produced by the testes and/or adrenal glands that has masculinizing effects. ANERGY (adjective ANERGIC): lack of an immune response to a foreign antigen. ANOGENITAL: refers to the area that includes the genitals, perineum and anus. ANOREXIA: the lack or loss of appetite for food. ANTAGONIST: a substance that blocks the activation of a specific cellular function by binding to a cell's receptors. ANTIBODY (IMMUNOGLOBULIN): a protein secreted by activated plasma cells, which evolve from B-cells, in response to stimulation by an antigen. ANTICHOLINERGIC: a drug (e.g., tricyclic antidepressant) that antagonizes the action of the neurotransmitter acetylcholine and affects parasympathetic neural transmission. ANTIEMESIS (adjective ANTIEMETIC): relief of nausea and vomiting. ANTIGEN: any agent or substance (e.g., microorganisms or the substances they produce) that stimulates an immune response. ANTIMOTILITY: an agent that slows peristalsis, the muscle contractions that move food through the gastrointestinal tract. 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. APOPTOSIS: programmed cell death. ASIL: anal squamous intraepithelial lesion. ATYPIA: a condition of being abnormal or not typical. B BACTEREMIA: the presence of bacteria in the blood. BASELINE: a known value (e.g., baseline CD4 cell count) to which later measurements can be compared. 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. BENIGN: denoting a mild illness or a non-malignant neoplasm. BILE: a substance produced by the liver that aids in the digestion of fats. BIOAVAILABILITY: the extent to which a drug is absorbed and circulated in the body. BLOOD-BRAIN BARRIER: a physical barrier between the blood vessels and the brain that is selectively permeable, i.e., allows only certain substances to pass through. BODY CELL MASS (BCM): muscle and organ tissue. BRANCHED-CHAIN DNA ASSAY (bDNA): an assay for measuring the amount of virus (viral load) in blood plasma or tissue. C CAMPYLOBACTER: a family of bacteria that may cause acute illness affecting the small intestine, characterized by abdominal pain, nausea, vomiting, fever and bloody diarrhea. CANCER: a malignant neoplasm or tumor which may invade surrounding tissues and/or spread to different sites. CANDIDIASIS: a disease caused by a species of the yeast-like fungus Candida, usually C. albicans. Candidiasis can affect the skin, nails and mucous membranes throughout the body including the mouth (thrush), esophagus, vagina, intestines and lungs. CANNABINOID: an active component of Cannabis sativa, or marijuana. 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. CCR5: a protein found on certain blood cells that acts as a receptor site for chemokines. CD4: a protein marker on the surface of certain types of T-lymphocytes and other cells. HIV uses the CD4 receptor to enter a cell. 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. CD4 cells engulf and process invaders (e.g., viruses) and release cytokines that coordinate a broad range of immune system activities. 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). CD38: a cell surface marker found on certain CD8 T-lymphocytes. CELLULAR IMMUNITY (TH1 RESPONSE): the immune response mediated by the Th1 subset of CD4 cells. Cell-mediated immunity is stimulated by the cytokines IL-2, IL-12 and gamma interferon, and carried out by cytotoxic T-lymphocytes (CTL) and macrophages. CENTERS FOR DISEASE CONTROL AND PREVENTION (CDC): the U.S. federal agency within the Department of Health and Human Services that monitors disease occurrence and develops policies for preventing diseases and maintaining the health of the population. CEREBROSPINAL FLUID (CSF): a clear, nutrient-rich fluid that circulates around and through the brain and the spinal cord. CIRRHOSIS: a condition in which the liver becomes scarred, fibrous and filled with fat. 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. Certain chemokines (e.g., MIP-1-alpha, MIP-1-beta, RANTES) have been shown to affect the activity of HIV; certain chemokine receptors (e.g., CCR5, CXCR4) are necessary for entry by HIV into cells. CHOLANGITIS: inflammation of the bile ducts, often characterized by jaundice. CLADE: a distinct strain or subtype of a microorganism. CLONE: a group of genetically identical cells or organisms derived from a single common ancestor. COLITIS: inflammation of the colon, or large bowel. COLONOSCOPY: examination of the large intestine using a narrow, flexible lighted tube. COLPOSCOPY: examination of the tissues of the uterine cervix or the anal canal using with a low-powered, lighted microscope (colposcope) to identify abnormal cell growth and, if necessary, to remove a tissue sample for biopsy. COMPARTMENT: a distinct area or part of the body, which may not have a discrete physical boundary. CONDYLOMATA ACUMINATA: genital and/or anal warts caused by infection with a strain of human papillomavirus. CONTRAINDICATION: any circumstance or symptom that makes a therapy inadvisable. CONTROLLED TRIAL: a clinical trial in which a group receiving an experimental therapy is compared to a control group that is not given the intervention under study. CO-RECEPTOR: a second receptor required for entry into a cell or initiation of a biological process. CREATININE: a protein in muscles and blood; a metabolic waste product of muscle activity eliminated in the urine. CROHN'S DISEASE: a type of enteritis, or inflammation of the intestines. CROSS-RESISTANCE: the development of resistance to one agent (e.g., drug) which also confers resistance to another (often similar) agent. CRYOTHERAPY: the use of liquid nitrogen to freeze an abnormal lesion. 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. CSIL: cervical squamous intraepithelial lesion. CXCR4 (FUSIN, LESTR): a co-receptor on the surface of certain T-cells that, along with the CD4 molecule, allows HIV to infect a cell. 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. CMV infection often occurs in healthy individuals without causing symptoms. In immunocompromised individuals CMV may cause retinitis, pneumonia, colitis and/or encephalitis. CYTOPATHIC: related to disease, disorders or destruction of cells. CYTOTOXIC T-LYMPHOCYTE (CTL, T-KILLER CELL): an immune system white blood cell that targets and kills cells infected with microorganisms. D DESENSITIZATION: the reduction of sensitivity to an antigen or a drug, typically achieved by administering a small amount and gradually increasing the dose. DISSEMINATE: to spread; a disseminated infection is one that is distributed throughout the body. DIURETIC: an agent that increases the amount of urine excreted. 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. DOPAMINE: a neurotransmitter chemical in the brain that is involved in numerous processes, including regulation of mood. DOUBLE-BLIND: a type of clinical trial in which neither the subject nor the investigator knows what treatment, if any, the subject is receiving. DUODENUM: the first part of the small intestine where it meets the stomach. DYSPLASIA: the abnormal development or growth of cells and tissues; precancerous tissue changes. DYSTONIA: lack of or changes in muscle tone. E EFFICACY: effectiveness; the ability to achieve a desired effect. ELECTROCAUTERY: a method of destroying lesions or tissue using a high frequency electric current. ELECTROLYTE: an electrically charged element or compound (e.g., sodium, potassium) found in body fluids, tissues and cells. ENCEPHALITIS: 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). ENDOMETRITIS: inflammation of the endometrial tissue, the mucous membrane that lines the uterus. 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. ENDPOINT: a direct marker of disease progression, e.g., disease symptoms or death. ENTERITIS: inflammation of the intestines, especially the small intestine. 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. EPSTEIN-BARR VIRUS (EBV, HHV-4): a herpesvirus. EBV infection is common in children and may cause infectious mononucleosis in young adults; it is associated with oral hairy leukoplakia, lymphoid interstitial pneumonitis and some types of cancer in people with HIV disease. ESOPHAGITIS: inflammation of the esophagus, the swallowing tube between the oral cavity and the stomach. ETIOLOGY (adjective ETIOLOGIC): the cause of a disease. F FOLLICULAR DENDRITIC CELL: a specialized immune cell in lymph nodes that traps and concentrates foreign antigens for recognition by lymphocytes. FOOD AND DRUG ADMINISTRATION (FDA): the federal agency responsible for regulating the development, use and safety of drugs, medical devices, food, cosmetics and related products. G GALL BLADDER: an organ in the abdomen in which bile is stored. GASTROENTERITIS: inflammation of the lining of the stomach and intestines. 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. GLUTATHIONE: an antioxidant containing the amino acid cysteine which is involved in cell synthesis and amino acid transport. GP120: a glycoprotein on the outer envelope of HIV that binds to the CD4 protein on the surface of certain cells. H HAART: highly active antiretroviral therapy, a term for aggressive anti-HIV treatment using a combination of drugs. HEPATITIS: an inflammation of the liver that may be caused by several agents, including viruses and toxins. Hepatitis is characterized by jaundice, enlarged liver, fever, fatigue and abnormal liver function tests. HERPES SIMPLEX VIRUS (HSV-1, HSV-2): a herpesvirus that causes blisters and recurring disease. HSV-1 usually produces lesions on the lips or in the mouth ("cold sores" or "fever blisters"); HSV-2 is usually sexually transmitted and lesions generally occur in the genital and/or anal area. HERPESVIRUS: a group of viruses that includes herpes simplex virus types 1 (HSV-1) and 2 (HSV-2), varicella-zoster virus (VZV, HHV-3), Epstein-Barr virus (EBV, HHV-4), cytomegalovirus (CMV, HHV-5), human herpesvirus types 6 and 7 (HHV-6, HHV-7) and Kaposi's sarcoma-associated herpesvirus (KSHV, HHV-8). HISTAMINE: a cytokine released by basophils and mast cells in response to exposure to a foreign antigen. HISTOPATHOLOGY: the study or examination of abnormal or diseased tissue. 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, anal and oral cancer. HUMORAL IMMUNITY (TH2 RESPONSE): the immune response mediated by the Th2 subset of CD4 cells. Humoral immunity is stimulated by the cytokines IL-4 and IL-10, and carried out by plasma cells (derived from B-cells), which produce antibodies. I ILEUM: the final, longest and narrowest section of the small intestine. ILEUS: obstruction of a part of the small intestine. 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. IMMUNOGLOBULIN (IG): see antibody. IMMUNOMODULATOR (IMMUNE MODULATOR): a substance or process capable of modifying functions of the immune system. INCIDENCE: the number of new cases of a diseases or condition in a specific population over a given period of time. 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. INTERFERON: one of a family of some 20 cytokines (messenger proteins) that play a role in immune response. Interferon-alpha is used as a treatment for genital warts. INTERLEUKIN (IL): a cytokine secreted by immune cells that regulates a range of immune system functions. 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: yellow discoloration of the skin and whites of the eyes caused by the inability of the liver to break down the pigment bilirubin. JC VIRUS: a human virus thought to be the cause of progressive multifocal leukoencephalopathy. 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. KAPOSI'S SARCOMA-ASSOCIATED HERPESVIRUS (KSHV, HHV-8): a recently discovered herpesvirus that is found in Kaposi's sarcoma lesions and may be a causal agent or co-factor. KIDNEY STONE (NEPHROLITHIASIS): an accumulation (e.g., of minerals, drug residue) in the kidney, which may lead to blockage and pain. KILLER T-CELL: see cytotoxic T-lymphocyte. L LACTOSE: a sugar found in milk and other dairy products. Lactose intolerance is characterized by digestive disturbances due to the lack of a digestive enzyme (lactase) that breaks down lactose. LEAN BODY MASS: muscle and organ tissue. LEUKOCYTE: an immune system white blood cell (e.g., monocyte, CD4 cell). Various types of leukocytes are involved in the body's defense against infection and disease. 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). LISTERIOSIS: infection caused by Listeria monocytogenes, an aerobic bacteria that may be present in meat, poultry and raw or unpasteurized milk products. LOG: refers to quantities in factors of 10. A log change is an exponential or 10-fold increase or decrease (e.g., 10 to 100 is a 1-log increase). LYMPHADENOPATHY: any abnormality of the lymph nodes. Usually refers to swollen and tender lymph nodes due to an infectious disease or lymphoma. LYMPHATIC SYSTEM: a network of capillary-like vessels, ducts, nodes and organs that helps maintain the fluid environment of the body and coordinates immune responses. The lymphoid organs include the lymph nodes, spleen, thymus, tonsils and adenoids. LYMPH NODE: a small, bean-sized organ located throughout the body. Lymph nodes filter out antigens and are the site of antigen presentation and immune activation. LYMPHOCYTE: a type of white blood cell (e.g., T-cell, B-cell) responsible for immune defense. LYMPHOMA: a malignant disease (cancer) originating in the lymph nodes. M MACROLIDE: a class of antibiotic drugs (e.g., clarithromycin, azithromycin) related to erythromycin. MACROPHAGE: a large scavenger white blood cell that ingests degenerated cells and foreign particles and secretes messenger proteins (monokines) involved in a variety of immune system responses. MALABSORPTION: decreased absorption of nutrients by the intestines, for example due to damage to the tissues lining the digestive tract. MALIGNANCY (adjective MALIGNANT): a cancer, neoplasm or tumor that grows in an uncontrolled manner, invading nearby tissue and metastasizing (spreading) to other sites through the bloodstream. MENINGITIS: an inflammation of the meninges, the membrane envelopes that encase 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 (catabolism). METASTASIS (adjective METASTATIC): shifting of a disease manifestation from one site in the body to another, in particular the spread of cancer from a primary or original site to another part of the body. MICROBICIDE: an agent that inactivates, kills or destroys microbes. Vaginal and anal microbicides are under study as a means of preventing HIV transmission. MICROSPORIDIOSIS: infection with a protozoan parasite of the Microsporidia family (e.g., Enterocytozoan bieneusi, Septata intestinalis) often characterized by diarrhea and weight loss. 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. MONONUCLEAR CELL: a cell that has 1 nucleus, used to refer to a subset of white blood cells (e.g., lymphocytes, monocytes). MONOTHERAPY: use of a single drug or other therapy. MYALGIA: pain in the muscles. MYCOBACTERIUM AVIUM COMPLEX (MAC): a disease caused by Mycobacterium avium or Mycobacterium intracellulare, bacteria found in soil and water. MYCOPLASMA: a microorganism, of which there are many varieties (e.g., Mycoplasma penetrans), that usually does not cause disease in people with healthy immune systems. N N-ACETYL CYSTEINE (NAC): a substance which is converted within the body to cysteine, an amino acid that is a component of glutathione, a major cellular antioxidant. NATURAL KILLER CELL (NK CELL): a type of lymphocyte that attacks and kills tumor cells and cells infected with microorganisms. NAUSEA: stomach distress characterized by an aversion to food and an urge to vomit. NEOPLASIA: the disease process involved in the growth of a neoplasm. 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. A benign neoplasm (e.g., a wart) does not spread to other tissues; a malignant (cancerous) neoplasm has the potential to spread (metastasize) to other sites. NEUROTRANSMITTER: a chemical messenger (e.g., acetylcholine, dopamine, serotonin) used to communicate among neurons and between neurons and other types of cells. NEUTROPENIA: an abnormally low number or a decrease in the number of neutrophils, a type of white blood cell involved in defense against bacteria and fungi. NONOXYNOL-9: a surfactant chemical used as a spermicide and microbicide (e.g., in contraceptive foams, as a lubricant on condoms). NON-NUCLEOSIDE REVERSE TRANSCRIPTASE INHIBITOR (NNRTI): a drug (e.g., delavirdine, nevirapine) that binds to and inhibits the action of the retroviral reverse transcriptase enzyme, thus blocking viral replication. NUCLEOSIDE ANALOG (NA): a compound (e.g., AZT, ddI, ddC, d4T, 3TC) 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 viral DNA chain. O ONCOGEN: an agent (e.g., virus. toxin) that is able to cause neoplastic cell growth, or cancer. Oncogenesis is the development and growth of a neoplasm or tumor. ONCOLOGY: the medical specialty that deals with cancer. OPIOID (OPIATE, NARCOTIC): a class of drugs (e.g., heroin, codeine, methadone) that are derived from the opium poppy plant, contain opium, or are produced synthetically and have opium-like effects. Opioid drugs relieve pain, dull the senses and induce sleep. OPPORTUNISTIC INFECTION (OI): a disease (e.g., PCP, MAC, CMV disease) caused by a microorganism that does not normally cause disease in a person with a healthy immune system, but which may cause serious illness when the immune system is suppressed. OXIDATIVE STRESS: increased levels of free radicals and other oxidation-promoting molecules that may result in cell membrane damage, cell death and damage to genetic material. P PANCREATITIS: inflammation of the pancreas, a digestive gland in the abdominal cavity. 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 for abnormal cell growth. 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. PCR: polymerase chain reaction. PELVIC INFLAMMATORY DISEASE (PID): infection of the upper female reproductive tract including the uterus, fallopian tubes and ovaries. 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. PERISTALSIS: the rhythmic contractions of muscles surrounding the digestive tube that move food through the gastrointestinal tract. PEYER'S PATCHES: regions of immune cells in the lining of the gastrointestinal tract. PHARMACOKINETICS: the action of drugs in the body, including the processes of absorption, transformation, distribution to tissues and elimination. PHASE I TRIAL: the first step in human testing of a new drug; these trials evaluate drug safety and toxicity at different dose levels in a small number of volunteers. PHASE II TRIAL: the second step in the evaluation of a new drug in humans; these trials evaluate drug effectiveness and involve more participants than Phase I studies. PHASE III TRIAL: the third step in human drug testing; these trials are designed to support and verify information gathered in Phase I and II trials, and involve many more volunteers. Phase III trials may compare the drug being tested to other therapies or to placebo. PHENOTYPE (adjective PHENOTYPIC): visible characteristics and/or behaviors that result from the interaction of an organism's genetic "blueprint" (genotype) and the environment. 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. PNEUMOCYSTIS CARINII PNEUMONIA (PCP): a life-threatening type of pneumonia caused by a protozoan. PCP is a common opportunistic infection and a leading cause of death in people with AIDS. 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 PROPHYLAXIS: drug therapy given immediately following exposure to an infectious organism, done 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: the initial introduction of HIV into the body; the earliest stage of HIV disease. PROCTITIS: inflammation of the mucous membranes of the rectum. PROGRESSIVE MULTIFOCAL LEUKOENCEPHALOPATHY (PML): a rapidly progressing, often fatal brain disease believed to be caused by the JC papovavirus. PROPHYLAXIS (adjective PROPHYLACTIC): therapy that helps to prevent a disease or condition before it occurs (primary prophylaxis) or recurs (secondary prophylaxis). PROTEASE INHIBITOR: a drug (e.g., saquinavir, indinavir, ritonavir, nelfinavir) that blocks the action of the protease enzyme that breaks up large proteins produced from viral RNA, thereby preventing HIV replication. PROTOZOAN: an acellular or 1-celled microorganism, several of which can cause disease in humans. R 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. When chemicals bind to receptors, various cellular functions are activated or inhibited. Viruses enter cells by fusing with receptors on the cell surface. RENAL: pertaining to the kidneys. RESERVOIR: a site where an infectious agent collects and multiplies (e.g., macrophages and lymph nodes are thought to be reservoirs for HIV). RESISTANCE: the ability of a microorganism to mutate in such a way that it loses its sensitivity to a drug. RETINITIS: an inflammation of the retina, the light-sensitive tissue at the back of the eyeball. RETROVIRUS: a class of enveloped viruses that have their genetic material in the form of RNA and use reverse transcriptase to translate their RNA into DNA. REVERSE TRANSCRIPTASE INHIBITOR (RTI): a drug that blocks retroviral replication by interfering with the reverse transcriptase enzyme that allows a retrovirus to translate its genetic material (in the form of RNA) into DNA. RTI include nucleoside analogs (e.g., AZT, ddI, 3TC) and non-nucleoside reverse transcriptase inhibitors (e.g., nevirapine). RNA (RIBONUCLEIC ACID): a single-stranded nucleic acid made up of nucleotides. 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. S SALMONELLOSIS: infection caused by Salmonella, bacteria commonly found in raw meat, poultry, eggs and milk products. The 3 forms of salmonellosis in humans are typhoid fever, septicemia (blood poisoning) and acute gastroenteritis, which can cause severe diarrhea and death if untreated. SENSITIVITY: the ability of an organism to be affected by a drug or other agent. SEROCONVERSION: the development of antibodies against a microorganism; the change in a person's antibody status from negative to positive. SET POINT: the level of viral load measured after seroconversion, when the initial burst of viremia has subsided. SEXUALLY TRANSMITTED DISEASE (STD): a disease (e.g., gonorrhea, syphilis, chlamydiasis) that is transmitted through sexual contact. SHIGELLOSIS: infection caused by Shigella bacteria. Shigellosis can cause digestive disturbances ranging from mild diarrhea to severe dysentery. SIGMOIDOSCOPY: examination of the sigmoid colon (the lower transverse part of the colon) with a lighted flexible viewing tube. SPINDLE CELL: an unusually shaped cell found in Kaposi's sarcoma lesions. SPLEEN (adjective SPLENIC): a lymphoid organ located in the abdominal cavity. The spleen stores and disposes of red blood cells and platelets and is a reservoir for macrophages. SQUAMOUS INTRAEPITHELIAL LESION (SIL): abnormal cell growth and changes, particularly of cells at the squamo-columnar junction of the uterine cervix (CSIL) or anal canal (ASIL). Low-grade SIL is mild cellular atypia. High-grade SIL refers to more severe neoplasia or cancer. STATISTICAL SIGNIFICANCE: the probability that an observed outcome of an experiment or trial is due to chance alone. STEROID: a family of substances that share a similar chemical structure, including certain hormones (e.g., testosterone) and various drugs. SURROGATE MARKER: a marker or sign (e.g., viral load or CD4 cell count) that can serve in place of a clinical endpoint. SYNCYTIUM (plural SYNCYTIA): a clump of cells whose membranes have fused to form a "giant cell." Strains of HIV are classified as either syncytia-inducing (SI) strains, which promote syncytia formation and tend to infect T-cells, and non-syncytia-inducing (NSI) strains, which tend to infect macrophages. SYNERGY (SYNERGISM): the action of 2 or more agents (e.g., drugs) working together to produce an effect greater than the combined effect of the same agents used separately. SYSTEMIC: affecting the whole body; not localized. T TAT: transactivator of transcription, a gene of HIV that plays a role in viral replication by regulating the transcription of viral DNA into RNA; also the protein produced by the tat gene. T-CELL (T-LYMPHOCYTE): a type of white blood cell derived from the thymus which 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). TETRAHYDROCANNABINOL (THC): an active ingredient of marijuana. THC has psychoactive properties, may induce euphoria and drowsiness, and may improve appetite and reduce nausea due to chemotherapy. Dronabinol (Marinol) is a synthetic form of THC. THROMBOCYTE (PLATELET): a type of blood cell that facilitates normal blood clotting. THYMUS (adjective THYMIC): a lymphoid organ in the upper chest cavity. The thymus is the site of T-cell differentiation, where the cells learn to recognize antigens. TOTAL PARENTERAL NUTRITION: a regimen that delivers all nutrients intravenously, bypassing the gastrointestinal tract. TOXICITY (adjective TOXIC): the quality of being poisonous or harmful; often used to refer to side effects of drugs. TOXIN: a harmful or poisonous agent. TOXOPLASMOSIS: an opportunistic infection caused by the microscopic protozoan Toxoplasma gondii. A common manifestation is toxoplasmic encephalitis, characterized by brain swelling, dementia, confusion, lethargy, seizures and coma. TRADITIONAL CHINESE MEDICINE (TCM): an Asian system of healing that focuses on achieving internal balance. TCM practitioners use methods such as acupuncture, heat application (moxibustion), herbal preparations and exercises (e.g., tai chi, qigong) to restore the flow of qi (vital energy) and the balance of yin and yang. TRANSFORMATION ZONE: the area (e.g., in the uterine cervix or anal canal) where squamous and columnar epithelial cells meet and overlap; a common site for squamous intraepithelial lesions. TUMORIGENESIS: the growth and development of a tumor, or accumulation of rapidly proliferating cells. TUMOR NECROSIS FACTOR (TNF, CACHECTIN): a cytokine, produced by activated monocytes and macrophages, that can destroy tumors. U UNDETECTABLE: a term used to describe a viral load that is below the level of detection of the test being used. UREMIA: an excess blood level of urea, a metabolic waste product normally excreted in the urine. V VARICELLA-ZOSTER VIRUS (VZV, HHV-3): a herpesvirus that initially causes chickenpox (varicella); VZV may lie dormant within the nerves and reactivate later to cause herpes zoster (shingles). VIRAL LOAD (VIRAL BURDEN): the amount of virus in the blood or other tissues. The presence of viral genetic material 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 PCR or bDNA. VIREMIA: the presence of virus in the blood or plasma. VIRULENT: aggressive, able to cause disease. VIRUS: a group of minute organisms that are unable to grow or reproduce outside the body 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 viral particles. W WASTING SYNDROME: a condition characterized by atrophy of lean body mass and involuntary weight loss of more than 10% of normal body weight. Page last updated 2 July 1997 |
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