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Published in the Bulletin of Experimental Treatments for AIDS March 1997 issue, by the San Francisco AIDS Foundation. |
GlossaryCompiled by Liz Highleyman ACCELERATED APPROVAL: FDA regulations governing early marketing approval of promising drugs for life-threatening illnesses. 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 (initial) HIV infection or occurs shortly after infection. AIDS CLINICAL TRIALS GROUP (ACTG): a NIAID-sponsored group of medical centers, known as AIDS Clinical Trials Units (ACTU), that evaluate treatments for HIV disease and associated illnesses. AIDS DEMENTIA COMPLEX (ADC, HIV ENCEPHALOPATHY, HIV-ASSOCIATED DEMENTIA): mental impairment due to HIV infection (i.e., not an opportunistic pathogen). Symptoms may include cognitive impairment (e.g., difficulty concentrating, memory loss), disorientation, mood and personality changes, speech and vision difficulties, psychomotor dysfunction (lack of coordination, incontinence) and paralysis. ALLELE: a "version" of a specific gene. Each individual has 1 allele (from one or the other parent) at each specific genetic location. ALOPECIA: hair loss. AMINO ACID: an organic compound that is a basic structural unit of peptides and proteins. AMPHETAMINE: a psychostimulant drug that acts on the central nervous system. ANABOLIC STEROID: a hormone (e.g., testosterone, oxandrolone) that promotes the synthesis of proteins and the building of muscle mass. ANALGESIC: a drug or therapy that reduces perception of or sensibility to pain. ANAPHYLAXIS: a life-threatening allergic reaction to a foreign antigen mediated by IgE antibodies. Symptoms include swelling, shortness of breath and a decrease in blood pressure. ANDROGENIC STEROID: a hormone (e.g., testosterone, androsterone) that has masculinizing effects, including stimulation of the male reproductive organs and development of male secondary sex characteristics. ANEMIA: an abnormally low number of red blood cells. ANERGY (adjective ANERGIC): the lack of an immune response to a foreign antigen. ANGIOGENESIS: the growth and proliferation of blood vessels. ANOSCOPY: examination of the anal canal and lower rectum using a short speculum. ANTIARRHYTHMIC: a drug that helps to normalize the rhythm of the heartbeat. ANTIBODY (AB, IMMUNOGLOBULIN, IG): a protein secreted by activated plasma cells, which evolve from B-cells, in response to stimulation by an antigen. The antigen/antibody reaction forms the basis of humoral (Th2) immunity. There are 5 types of antibodies: IgA, IgD, IgE, IgG and IgM. ANTICONVULSANT: an agent that prevents or lessens convulsions or seizures; may be used as an adjuvant analgesic. ANTIGEN: any agent or substance (e.g., microorganisms or the substances they produce) that stimulates an immune response. Antigenemia is the presence of antigens in the blood. ANTIPSYCHOTIC: a drug that reduces symptoms of psychosis. ANTIRETROVIRAL: an agent that suppresses the activity or replication of retroviruses such as HIV. APOPTOSIS: programmed cell death. ARM: a group of participants in a clinical trial who all receive the same treatment (treatment arm) or placebo (control arm). ASSAY: a test used to detect the presence of a drug, substance or microorganism in the blood or tissues. ATYPIA: a condition of being abnormal or not typical. AXON: a long process of neurons that conducts neural impulses to muscles, tissues and organs. AZOLE DRUG: a class of drugs used to fight fungal infections. BACTEREMIA: the presence of bacteria in the blood. BARBITURATE: a class of drugs (e.g., phenobarbital) that have sedative properties and depress respiratory rate, blood pressure and nervous system activity. BASELINE: a known value (e.g., baseline CD4 cell count) to which later measurements can be compared. BASOPHIL: a type of white blood cell (granulocyte) that releases chemicals in allergic reactions; basophils that leave the bloodstream become mast cells in the tissues. 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. BIOAVAILABILITY: the extent to which a substance (e.g., a drug) is absorbed and circulated in the body. BIOPSY: the surgical removal of a small piece of tissue for microscopic examination and/or culture. BLOOD-BRAIN BARRIER: a barrier between the blood vessels and the brain that is selectively permeable, i.e., allows only certain substances to pass through. BODY CELL MASS: muscle and organ tissue. BONE MARROW: the soft, spongy tissue in the interior of certain bones that is the site of hematopoiesis, or blood cell production. BRANCHED-CHAIN DNA ASSAY (bDNA): an assay for measuring the amount of virus (viral load) in blood plasma or tissue. 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 (yeast infection), intestines and lungs. CAPSAICIN: a derivative of red pepper that is used as a topical analgesic, especially for the pain of peripheral neuropathy. CARCINOGEN: a chemical or physical agent (e.g., a drug, radiation) that facilitates the development of cancer. CCR-5 (CKR-5): a protein found on certain blood cells that acts as a receptor site for chemokines; CCR-5 binds with the chemokines MIP-1 alpha, MIP-1 beta and RANTES. CCR-5 functions as a co-receptor which HIV uses to infect cells. Individuals who lack 2 functional copies of the gene that makes CCR-5 are believed to be non-susceptible to HIV infection. CD4: a protein marker on the surface of certain types of T-lymphocytes and other cells. HIV uses the CD4 receptor to enter the 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. The CD4 cell count is the number of CD4 lymphocytes in a cubic millimeter (mm3) of blood. 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). CELL ANTIVIRAL FACTOR (CAF): a soluble substance produced by CD8 cells that inhibits HIV replication in infected cells. CELL-MEDIATED IMMUNITY (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. 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. CERVICAL INTRAEPITHELIAL NEOPLASIA (CIN): abnormal growth of cells of the uterine cervix, suggestive of an early stage of cervical cancer. CHEMOATTRACTANT: a factor that attracts cells (e.g., immune system white blood cells) to places in the body where they are needed. 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. Alpha chemokines contain an amino acid between 2 cysteine residues; beta chemokines do not contain an intervening amino acid. 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., CCR-5, CXCR-4) are necessary for entry by HIV into cells. CLINICAL TRIAL: an organized procedure for determining the effectiveness of new drugs or therapies by administering the agent to participants under strictly controlled conditions. COHORT: a group of individuals in a study who share a statistical factor (e.g., age, study site). COLONY-STIMULATING FACTOR (CSF): a cytokine responsible for regulating the production of white blood cells. CONDYLOMATA ACUMINATA: genital and/or anal warts caused by infection with a strain of the human papillomavirus (HPV). CONGENITAL: present from the time of birth. CONTRAINDICATION: any circumstance or symptom that makes a method of treatment inadvisable in a particular case. 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. HIV requires both the CD4 receptor and a co-receptor (e.g., CCR-5 or CXCR-4) to enter a cell. CORTICOSTEROID: a steroid hormone with anti-inflammatory and immunosuppressive properties. CREATININE: a protein in muscles and blood. 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. Symptoms include severe, chronic diarrhea. CUTANEOUS: pertaining to the skin. CXCR-4 (FUSIN, LESTR): a co-receptor on the surface of certain T-cells that, along with the CD4 molecule, allows HIV to infect a cell. The CXCR-4 receptor binds with the chemokine SDF-1. CYTOCHROME P450 SYSTEM (CP450): a process that metabolizes drugs and other foreign substances in the liver by means of enzymes. CYTOLYSIS: destruction of a cell by rupturing. CYTOKINE: an intercellular chemical messenger protein released by white blood cells. Cytokines facilitate communication among immune system cells and between immune system cells and the rest of the body. CYTOLOGY: the study of the structure, function and pathology of cells. 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. CYTOTOXIC T-LYMPHOCYTE (CTL, T-KILLER CELL): an immune system white blood cell that targets and kills cells infected with microorganisms. CYTOTOXICITY: the quality of being toxic to or killing cells. DATA SAFETY AND MONITORING BOARD (DSMB): a group of experts that evaluates clinical trials for safety and ethics. DEHYDRATION: loss or lack of water in the body. Dehydration may result from prolonged vomiting or diarrhea, and may interfere with or disrupt bodily processes. DELIRIUM: a state of mental confusion, typically acute and rapid in onset; that may be caused by factors including disease, drug use and high fever. DEMENTIA: chronic loss of mental capacity due to an organic cause. Dementia may involve progressive deterioration of thinking, memory, behavior, personality and motor function, and may also be associated with psychological symptoms such as depression and apathy. DEMYELINATION: destruction or loss of the myelin (a fatty substance) sheath that surrounds and insulates the axons of nerve cells and is necessary for the proper conduction of neural impulses. DEOXYRIBONUCLEOTIDE: a structural component or building block of DNA. DES: diethystilbestrol, a drug used in the 1940s and 1950s to treat menstrual disorders and prevent miscarriages. The drug was proven to be a transplacental carcinogen, causing reproductive tract cancer in the children of women who took the drug. DESENSITIZATION: the reduction of sensitivity to an antigen or a drug, typically achieved by administering a small amount and gradually increasing the dose. DHEA: dehydroepiandrosterone, a weak androgenic steroid produced by the adrenal cortex. DISSEMINATE: to spread; a disseminated infection is one that is distributed throughout the body. DISTAL PAINFUL NEUROPATHY: a type of peripheral neuropathy (nerve disease) common in people with HIV disease, characterized by burning or tingling sensations in the feet and hands. 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. 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. DYSREGULATION: interruption of or interference with normal processes. DYSTONIA: lack of muscle tone. EFFICACY: effectiveness; the ability to achieve a desired effect. ELECTROLYTE: an electrically charged element or compound (e.g., sodium, potassium) found in body fluids, tissues and cells. ELISA: a laboratory test used to detect the presence of antibodies in the serum. 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). ENDPOINT: a direct marker of disease progression, e.g., disease symptoms or death. ENZYME: a protein that induces or accelerates a chemical reaction. EOSINOPHIL: a granulocyte (a type of white blood cell) that plays a role in allergic reactions and defense against parasites. EPSTEIN-BARR VIRUS (EBV, HHV-4): a herpesvirus. EBV infection is common in children and may cause infectious mononucleosis in young adults. EBV lies dormant in the lymph nodes. It is associated with oral hairy leukoplakia, lymphoid interstitial pneumonitis and some types of cancer in people with AIDS. ESCAPE MUTANT: a drug-resistant strain; a microorganism (e.g., virus) that has mutated so as to lose its sensitivity to a drug. ETIOLOGY (adjective ETIOLOGIC): the cause of a disease; the study of causes of disease. EXOGENOUS: originating or produced outside the body. FASCICULATION: an involuntary contraction of a muscle. FOLLICULAR DENDRITIC CELL: a specialized 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. FREE RADICAL: a molecule that contains at least one unpaired electron. Free radicals are highly reactive and bind with other molecules, thus disrupting normal cellular processes and causing cellular damage (oxidative stress). FUSIN: see CXCR-4. GAMMA GLOBULIN: a type of antibody. GANGLION (plural GANGLIA): a cluster of nerve tissue primarily composed of neuron cell bodies. GASTROINTESTINAL: pertaining to 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. GESTATION: pregnancy. GP120: a glycoprotein on the outer envelope of HIV that binds to the CD4 protein on the surface of certain cells. GPCR: a chemokine receptor associated with KSHV that appears to be related to vascularization in Kaposi's sarcoma. GUILLAIN-BARRÉ SYNDROME (GBS, INFLAMMATORY DEMYELINATING POLYRADICULOPATHY): an acute, inflammatory disease of the nerve roots characterized by fever, sensory loss and bilateral muscular weakness or paralysis, most commonly in the legs and feet. HAART: highly active antiretroviral therapy, a term for aggressive anti-HIV treatment. 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). HORMONE: a chemical messenger involved in the regulation and coordination of cellular and bodily functions. HUMAN LEUKOCYTE ANTIGEN (HLA): a genetic marker of "self" which prevents the immune system from attacking the body's own tissues. 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 (ANTIBODY-BASED 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. HYDRATION: the addition of water; the replacement of body fluids by mouth or infusion. HYDROXYUREA (HYDREA): an agent approved for the treatment of leukemia and ovarian cancer and under study as a treatment for HIV disease. Hydroxyurea interferes with viral replication by inhibiting the cellular enzyme ribonucleotide reductase, resulting in a reduction of the supply of the deoxyribonucleotides needed to synthesize new DNA. HYPERSENSITIVITY: abnormal sensitivity; an exaggerated immune response to an antigen, drug, etc. 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. Immune modulators include cytokines (e.g., IL-2, gamma interferon) and broad-acting agents. IMMUNOSUPPRESSION (IMMUNOCOMPROMISE): reduced function of the immune system; a state in which the immune system defenses have been suppressed or weakened. INCIDENCE: the number of new cases of a diseases or condition in a specific population over a given period of time. INDUCTION: the initiation phase of a particular therapy. IN SITU HYBRIDIZATION: a method used to detect and locate specific DNA or RNA sequences. INTEGRASE: an enzyme produced by HIV that allows the integration of HIV DNA into the host cell's genetic material. INTERFERON: one of a family of some 20 cytokines (messenger proteins) that play a role in immune response. INTERLEUKIN (IL): a cytokine secreted by immune cells that regulates a range of immune system functions. Interleukin 2 (IL-2) promotes the proliferation and activity of other immune cells, and is under study as a immunomodulatory treatment for HIV disease. INTRACTABLE: resistant to treatment or symptomatic relief. INTRAEPITHELIAL NEOPLASIA: abnormal cell growth that suggests possible malignancy. Common sites are the anus (anal intraepithelial neoplasia) and the uterine cervix (cervical intraepithelial neoplasia). INTRAPARTUM: during birth. 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. KAPOSI'S SARCOMA (KS): an abnormal or cancerous proliferation of cells and 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 samples of tissue from Kaposi's sarcoma lesions, and may be a causal agent or co-factor. KIDNEY STONE (NEPHROLITHIASIS): an accumulation of minerals (e.g., calcium) in the kidney, which may lead to blockage and pain. KILLER T-CELL: see cytotoxic T-lymphocyte. 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, for example to obtain a sample for diagnosis. 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. LEUKOPENIA: an abnormally low number of white blood cells in the circulating blood. LIGAND: a molecule that binds to a specific receptor. 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). LIPOSOME (LIPID VESICLE): a spherical particle of fat suspended in a liquid medium. Liposomes may be used to carry drugs or other substances to cells or tissues. LITHIUM: a metallic element used to treat mania or bipolar affective disorder (manic-depression). 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). LOOP ELECTROSURGICAL EXCISION PROCEDURE (LEEP): use of a heated wire loop to remove a cone-shaped wedge from the bottom of the uterine cervix for biopsy. 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. LYMPHOKINE: a chemical messenger (e.g., interferon, interleukin) produced by lymphocytes that directs and regulates immune responses by stimulating macrophages, killer cells and other lymphocytes. LYMPHOMA: a malignant disease (cancer) originating in the lymph nodes. 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. MAGNETIC RESONANCE IMAGING (MRI): a sensitive, non-invasive method for viewing soft tissues of the body using a strong magnetic field. MAINTENANCE THERAPY (SECONDARY PROPHYLAXIS): preventive therapy that follows successful initial treatment of an illness. MALIGNANCY: 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). MICROBICIDE: an agent that inactivates, kills or destroys microbes. MICROSPORIDIOSIS: infection with a protozoan parasite of the Microsporidia family (e.g., Enterocytozoan bieneusi, Septata intestinalis); the condition often causes diarrhea and weight loss. MIP-1 ALPHA, MIP-1 BETA (MACROPHAGE INFLAMMATORY PROTEIN 1): a pair of recently discovered chemokines that (in association with RANTES) inhibit HIV replication. The 2 chemokines bind with the CCR-5 cell surface receptor. 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. MONONEURITIS: inflammation of a single nerve. 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. M-TROPIC: refers to strains of HIV that preferentially infect monocytes and macrophages. MYALGIA: muscle pain. MYCOBACTERIUM AVIUM COMPLEX (MAC): a disease caused by Mycobacterium avium or Mycobacterium intracellulare, bacteria found in soil and water. In immunosuppressed persons, the bacteria can infect lymph nodes, bone marrow, liver, spleen, spinal fluid, lungs and the gastrointestinal tract. Symptoms include diarrhea, wasting, fever, fatigue and spleen enlargement. NAIVE T-CELL: a subset of CD4 and CD8 cells that proliferate rapidly when exposed to new antigens. Naive cells are "uncommitted" and respond to general antigenic stimulation. NARCOTIC (OPIATE): 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. NEONATAL: newborn. NEOPLASIA: abnormal cell growth that may be precancerous. NEOPLASM: a tumor or growth. NERVE GROWTH FACTOR: a substance that sustains nerves and promotes the regeneration of damaged nerves. Recombinant human nerve growth factor (rhNGF) is used to treat peripheral neuropathy. NEUROLEPTIC: a drug that acts on the nervous system and modifies psychotic behavior. NEUROLOGIC: pertaining to the central nervous system (brain and spinal cord) or the peripheral nervous system (the nerves in the rest of the body). NEURON (NERVE CELL): a cell which conducts electric neural impulses from one part of the body to another. NEUROPATHY (adjective NEUROPATHIC): any abnormal, degenerative or inflammatory condition of the nerves. NEUROTRANSMITTER: a chemical messenger (e.g., 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. NEUTROPHIL: a type of white blood cell involved in defense against bacteria and fungi. NITRIC OXIDE: a reactive oxygen intermediate (free radical) that has several biological functions. NON-HODGKINS LYMPHOMA (NHL): a type of cancer of the lymph nodes; the most common type of lymphoma in people with HIV/AIDS. NON-NUCLEOSIDE REVERSE TRANSCRIPTASE INHIBITOR (NNRTI): a drug (e.g., delavirdine, nevirapine) that inhibits the action of the retroviral reverse transcriptase enzyme, thus blocking viral replication, yet works in a different way than nucleoside analog drugs. NON-STEROIDAL ANTI-INFLAMMATORY DRUG (NSAID): a drug (e.g., aspirin, ibuprofen) that relieves pain and reduces inflammation and fever, but which is not a steroid or a narcotic. 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. NUCLEOTIDE: one of the building blocks that make up the genetic material (DNA and RNA). Nucleotides consist of a base (adenine, cytosine, guanine, thymine or uracil), a sugar and a phosphate group. OFF-LABEL: refers to use of an FDA-approved drug for an indication other than that for which the drug was approved. OPEN-LABEL: a drug trial which is not randomized and not blinded; both participants and investigators know what drug is being tested and what dosages are being used. OPPORTUNISTIC INFECTION (OI): a disease (e.g., PCP, MAC, CMV disease) caused by a microorganism that usually does not cause disease in persons with healthy immune systems, but which may cause serious illness when the immune system is suppressed. p24: a core protein of HIV produced by the gag gene. 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 (dysplasia). PARESTHESIA: abnormal physical sensations such as numbness, prickling or tingling. PATHOGEN: 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: see polymerase chain reaction. 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 BLOOD MONONUCLEAR CELL (PBMC): a single-nucleus white blood cell (e.g., monocyte) that circulates in the blood. 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. PH: a logarithmic scale used to describe the acidity or alkalinity 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, transformation, distribution to tissues, duration of action 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 (up to several thousand). Phase III trials may compare the drug being tested to other therapies or to placebo. PHASE IV TRIAL: postmarketing studies done after regulatory approval has been granted and a drug has been offered for sale. PHENOTYPE (adjective PHENOTYPIC): visible characteristics and/or behavior 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. PLACENTA: the vascular organ that connects the fetus and the mother's uterus, through which metabolic exchange between the fetus and mother takes place. PLASMA: the fluid, non-cellular portion of circulating blood that carries blood cells and nutrients throughout the body. 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. POLYNEUROPATHY: a type of peripheral neuropathy that involves damage to multiple nerves. POLYRADICULOPATHY: a type of peripheral neuropathy characterized by the inflammation of nerve roots. POST-EXPOSURE PROPHYLAXIS: drug therapy given immediately following exposure to an infectious organism, done in an attempt to prevent the infection from gaining hold in the body. PREVALENCE: the number of individuals with a condition in a specific population. PRIMARY INFECTION: the initial introduction of an infectious organism into the body. PRODRUG: an inactive form of a drug that exerts its effects after metabolic changes within the body convert it to a usable or active form. PROGRESSIVE MULTIFOCAL LEUKOENCEPHALOPATHY (PML): a rapidly progressing, often fatal brain disease believed to be caused by the JC papovavirus. PROGRESSIVE MULTIFOCAL NEUROPATHY: a type of nerve disease associated with cytomegalovirus infection. PROINFLAMMATORY CYTOKINE: a chemical messenger (e.g., IL-6, tumor necrosis factor) produced by the body that promotes an inflammatory immune response. PROPHYLAXIS (adjective PROPHYLACTIC): chemotherapy that helps to prevent a disease or condition before it occurs (primary prophylaxis) or recurs (secondary prophylaxis). PROSPECTIVE STUDY: a study that looks forward in time. Patients are selected and their progression is followed. 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. PROVIRUS: a viral state in which viral DNA has been inserted into the chromosome of the host cell. PSYCHOSIS: a major mental disorder (e.g., schizophrenia, bipolar disorder) that affects the ability to function normally on a daily basis. PSYCHOTROPIC: an agent (e.g., thorazine) that affects psychic or mental functioning or behavior. QUINOLONE: a class of synthetic, broad spectrum antibiotic agents (e.g., ciprofloxacin). RADICULOMYELOPATHY: disease of the spinal cord. RANDOMIZED TRIAL: an experiment arranged so as to produce a chance distribution of subjects into different treatment groups or arms. RANTES (REGULATED-UPON-ACTIVATION, NORMAL T-EXPRESSED AND SECRETED): a recently discovered chemokine that (in association with MIP-1 alpha and MIP-1 beta) inhibits HIV replication. The chemokine binds with the CCR-5 cell surface receptor. 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. RECOMBINANT: produced by genetic engineering. RECONSTITUTION: rebuilding and restoring to functionality (e.g., reconstitution of a damaged immune system). REFRACTORY: resistant to treatment. REGIMEN: a formalized schedule (e.g., a drug-dosing regimen). 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 (e.g., a virus) 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. 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 reverse transcriptase to translate their RNA into DNA. The retrovirus family includes oncoviruses (e.g., HTLV-1) and lentiviruses (e.g., HIV-1, HIV-2). 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). RIBONUCLEOTIDE REDUCTASE: a viral enzyme which cuts ribonucleotides in order to create deoxyribonucleotides, the building blocks of DNA. Ribonucleotide reductase is essential for DNA replication. Drugs (e.g., hydroxyurea) that inhibit ribonucleotide reductase may enhance the activity of nucleoside analog drugs. 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. RUPTURE OF MEMBRANES (ROM): the breaking open of the amniotic sac surrounding the fetus prior to the start of labor and delivery. SALVAGE THERAPY: emergency treatment with an experimental drug of an illness that has not responded to standard therapy. SDF-1 (STROMAL CELL-DERIVED FACTOR): an alpha chemokine that binds with the cell surface receptor CXCR-4, the co-receptor for T-tropic HIV. SELECTIVE SEROTONIN REUPTAKE INHIBITOR (SSRI): a psychotropic drug (e.g., Prozac, Zoloft) that is used to relieve depression; SSRI drugs act by moderating levels of the neurotransmitter serotonin. SENSITIVITY: the ability of an organism to be affected by a drug or other agent (e.g., a virus is sensitive to AZT if AZT is able to prevent viral replication). SEROCONVERSION: the development of antibodies against a microorganism; the change in a person's antibody status from negative to positive. SEROTONIN: a neurotransmitter that has many effects, including blood vessel constriction and smooth muscle stimulation. SEXUALLY TRANSMITTED DISEASE (STD): a disease (e.g., gonorrhea, syphilis, chlamydiasis) that is transmitted through sexual contact. SIDE EFFECT: an action or effect of a drug other than that which is intended. The term usually refers to undesired or negative effects such as headache, skin rash or liver damage. SPLEEN: an organ of the lymphoid system located in the abdominal cavity. The spleen is a reservoir for macrophages and is an important part of the immune system. STATISTICAL SIGNIFICANCE: the probability that an observed outcome of an experiment or trial is due to chance alone. In general, a result of a clinical trial is considered statistically significant if there is a less than 5% probability that the difference observed would occur by chance alone if the treatments being compared were equally effective (i.e., a p-value of less than .05). STEM CELL: a precursor cell from which blood cells are derived. STEROID: a family of substances that share a similar chemical structure, including certain hormones (e.g., testosterone) and various drugs. Some steroid drugs are used to lessen inflammatory reactions. STRAIN: a specific genetic variant of a particular organism. SULFONAMIDE (SULFA DRUG): a class of sulfur-containing antibiotic drugs (e.g., sulfadiazine) which cause sensitivity or adverse reactions in many people. 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, tend to infect T-lymphocytes and are associated with rapid disease progression, 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-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). T-SUPPRESSOR CELL: a type of T-cell that bears the CD8 surface marker and helps to regulate the immune response. TH1 IMMUNITY: see cellular immunity. TH2 IMMUNITY: see humoral immunity. 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. The thymus produces some 30 hormones or thymic factors (e.g., thymodulin, thymopentin) that are involved in the regulation of immune function. TONSIL: one of 2 small immune system glands, made up of lymphoid tissue, located at the back of the throat. TOPICAL: pertaining to the surface of the skin; a medication applied to the skin. TOXICITY (adjective TOXIC): the quality of being poisonous or harmful; often used to refer to side effects of drugs. TOXICOLOGY: the study of the harmful effects of substances on the body. TOXOPLASMOSIS: an opportunistic infection caused by the microscopic parasite Toxoplasma gondii, found in raw or undercooked meat and cat feces. The disease often affects the brain (toxoplasmic encephalitis). TRANSGENIC: pertaining to a chromosome or an organism into which genes from another individual have been inserted. TRICYCLIC ANTIDEPRESSANT: a psychotropic agent that elevates the mood and prevents or alleviates psychological depression, and which may be used as an adjuvant analgesic to relieve the pain of peripheral neuropathy. TROPISM: an affinity for or the tendency to move toward a specific target; the attraction of a virus or other microorganism to a particular type of cell or host tissue (e.g., M-tropic HIV preferentially infects macrophages). T-TROPIC: refers to strains of HIV that preferentially infect T-lymphocytes. TUMOR NECROSIS FACTOR-ALPHA (TNF-ALPHA): a cytokine, produced by activated monocytes and macrophages, that can destroy tumors. UVEITIS: an inflammation of the membranes (uvea) of the eye. V3 (THIRD VARIABLE) LOOP: a part of the gp120 envelope protein of HIV. The V3 loop is the principle neutralizing determinant of HIV and triggers a strong antibody response, and is the basis of several candidate anti-HIV vaccines. 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). VASCULARIZATION: the growth and proliferation of blood vessels. VECTOR: an agent used as a vehicle for transfer. VINCA ALKALOID: a drug that arrests cell division, used as a chemotherapeutic treatment for many types of cancer. VIRAL LOAD (VIRAL BURDEN): 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 PCR or branched-chain DNA (bDNA). VIREMIA: the presence of virus in the blood or plasma. VIRION: a complete virus particle that exists outside of a host cell. 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. 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 specific antibodies (e.g., to HIV). The Western blot test is more accurate than the ELISA test, and is used as a confirmatory test if an ELISA test is positive. Page last updated 9 April 1997 |
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