Glossary of HIV/AIDS Terms
This glossary contains 1,600 terms and is maintained by the editors of the San Francisco AIDS Foundation's Bulletin of Experimental Treatments for AIDS.
A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z
cmax: See peak concentration.
cmin: See trough concentration.
cachexia: a condition of body wasting and general ill health.
calcium: a metallic trace element essential for bone maintenance and proper neural and muscular function.
caliper: an instrument used to measure diameter or thickness (e.g., of a skin fold).
calorie: a unit of measurement of heat or energy.
cancer: a malignant neoplasm or tumor characterized by abnormal proliferation of cells; types of cancer include carcinoma (affecting the epithelial cells), sarcoma (affecting soft tissues), and lymphoma (affecting lymphoid tissue).
Candida: a genus of yeast-like fungi. Some Candida species (e.g., C. albicans) are part of the normal flora of the mouth, intestines, and vagina, but can overgrow and cause disease (candidiasis, or thrush), especially immunocompromised individuals.
candidiasis: a condition caused by a Candida fungus, usually C. albicans. Candidiasis may affect the skin, nails, and mucous membranes throughout the body including the mouth, esophagus, and vagina; oral or vaginal candidiasis may be an early sign of immune impairment in people with HIV. See also oral candidiasis.
canker sore: See aphthous ulcer.
capillaries: tiny blood vessels that form the most distal part of the circulatory system; capillaries deliver oxygen and nutrients to and remove waste products from the body's cells.
carbohydrate: an organic molecule composed mainly of carbon, hydrogen, and oxygen atoms; carbohydrates constitute a major class of nutrients, and are present in foods such as bread and pasta.
carcinogen: a chemical or physical agent (e.g., a drug, radiation) that facilitates the development of cancer.
carcinogenesis (adjective carcinogenic): the development of cancer.
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.
cardiac: refers to the heart.
cardiomyopathy (aka myocardiopathy): a disease of the myocardium, or heart muscle.
cardiovascular: refers to the circulatory system (the heart and blood vessels).
caries: “cavities”; tooth decay.
carotid artery: one of the two major arteries in the neck that provide blood to the brain.
carrier: an individual who does not show symptoms or have active disease, but carries an infectious organism and can transmit it to others.
case study: a description of a specific clinical case, that is, the development of disease and response to treatment in a single individual.
case-control method: a type of study in which the progress of an individual with a disease or condition is compared with that of a healthy control matched on several variables.
CAT scan: See computed tomography scan.
catabolism: the breakdown of bodily proteins for energy and raw materials.
catalyst: an agent that promotes or accelerates a chemical reaction.
categories A, B, C, D, and X: a system used by the FDA to classify drugs based on their risk to the developing fetus when used during pregnancy. Category A drugs have not shown a risk in controlled studies; category B drugs either have not been tested in animals or show adverse effects in animals that have not been confirmed in humans; category C means that no controlled studies have been done in humans; category D indicates that there is evidence of human fetal risk, which may be outweighed by a drug?s benefits; and category X includes contraindicated drugs that have been shown to cause fetal abnormalities in animal and human studies or in real-world use.
catheter: a tube inserted into the body to introduce or remove fluids. Certain types of catheters are semipermanent lines implanted in a vein to infuse substances (e.g., drugs, nutrients) into the bloodstream; an indwelling catheter is inserted beneath the skin.
cautery: burning or cutting tissue by means of heat, chemicals, or an electric current.
CBC: See complete blood count.
cc: cubic centimeter, a unit of measurement often used for drug dosages.
CCR5: a protein found on certain cells that acts as a receptor for the chemokines MIP-1 alpha, MIP-1 beta, and RANTES; CCR5 functions as a coreceptor that enables certain strains of HIV to enter cells. See also chemokine. See also CXCR4.
CCR5 blocker: See entry inhibitor.
CD4: a protein marker on the surface of certain types of T lymphocytes and other cells; HIV binds to CD4 receptors to enter host cells.
CD4 cell (aka CD4 lymphocyte, aka helper T cell, aka T4 cell): a type of white blood cell that bears the CD4 surface receptor and helps coordinate a range of immune system activities. HIV impairs immune function by attacking and killing CD4 cells.
CD4 cell count (broadly T cell count): the absolute number of CD4 cells in one cubic millimeter (mm3) of blood. The CD4 cell count is one indicator of HIV disease progression. A normal CD4 cell count ranges from about 600 to 1,200 cells/mm3; moderate immunosuppression in adults is associated with a CD4 cell count between 200 and 500 cells/mm3, while severe immunodeficiency is associated with counts below 200 cells/mm3. Current U.S. federal guidelines recommend treatment when the CD4 cell count falls below 350 cells/mm3.
CD4 cell percentage: the number of CD4 cells as a proportion of the total number of lymphocytes; a normal CD4 cell percentage is 30-60%. CD4 cell percentage is a more consistent and reliable measure than absolute CD4 cell count.
CD4/CD8 ratio: the ratio of CD4 cells to CD8 cells; a normal CD4/CD8 ratio is 0.9-3.0.
CD8 cell (aka CD8 lymphocyte, aka T8 cell): a type of white blood cell that bears the CD8 cell surface marker and helps regulate or carry out the body's immune responses. The two subsets of T cells that express the CD8 marker are suppressor T cells and cytotoxic T lymphocytes (CTLs, or killer T cells). A normal CD8 cell count is 200-1,000 cells/mm3, and a normal CD8 cell percentage is 15-40%.
CDC:
See Centers for Disease Control and Prevention.
cell: the basic unit of living organisms; a typical animal cell contains a nucleus and a cell membrane surrounding the intracellular material, or cytoplasm.
cell antiviral factor (acronym CAF): a soluble substance that inhibits HIV replication in infected cells; the precise identity of this factor is not known.
cell line: a specific type of cell that is maintained in vitro for medical or research purposes.
cell membrane: the envelope surrounding an animal cell that encloses the cytoplasm and controls the movement of substances into and out of the cell.
cell-mediated immunity (acronym CMI, aka cellular immunity): a type of immune response coordinated by certain CD4 cells and carried out by cytotoxic T lymphocytes, activated macrophages, and natural killer cells. Cell-mediated immunity is particularly effective against virus-infected and cancerous cells. See also Th1 immune response. Compare with humoral immunity.
cellulitis: inflammation of subcutaneous connective tissue.
Centers for Disease Control and Prevention (acronym CDC): the U.S. federal government 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 (acronym CNS): the brain and spinal cord.
central obesity: accumulation of fat in the abdominal area, including internal fat around the visceral organs.
cerebral: refers to the brain; cerebrospinal refers to both the brain and spinal cord.
cerebrospinal fluid (acronym CSF): a clear, nutrient-rich fluid that circulates around and through the brain and spinal cord.
cerebrovascular: refers to the blood supply of the brain.
cerebrovascular accident: See stroke.
cervical cancer: cancer of the uterine cervix; invasive cervical cancer (cancer that has spread beyond the surface cell layers) is an AIDS-defining illness.
cervical intraepithelial neoplasia (acronym CIN): abnormal growth of cells of the uterine cervix. See intraepithelial neoplasia. See squamous intraepithelial lesion.
cervicitis: inflammation of the uterine cervix.
cervix (adjective cervical): the cylindrical, lower part of the uterus leading into the vagina.
cesarean section (aka C-section): a delivery procedure that involves making an incision through the abdominal wall to remove an infant from the uterus.
challenge: the deliberate exposure of an immunized animal to an infectious pathogen.
chancre: a red, painless ulcer; a primary sore or lesion that forms at the site of entry of a microorganism (e.g., the spirochete bacterium that causes syphilis).
chemokine: one of a family of soluble substances secreted by cells that act as chemical messengers, stimulating or inhibiting the activity of other cells. See also cytokine.
chemoprophylaxis: the use of chemical agents (e.g., drugs) to prevent disease.
chemotherapy (adjective chemotherapeutic): the use of chemicals (e.g., drugs) to treat disease; the term typically refers to cancer treatment.
chiropractic: a system of treatment based on the manipulation of the spinal vertebrae, the misalignment of which is believed to be responsible for pain and illness.
chlamydia: a disease, usually sexually transmitted, caused by the bacterium Chlamydia trachomatis; the most common sexually transmitted infection in the U.S. Chlamydia may be asymptomatic or may cause genital inflammation and discharge, pelvic pain, and fever; untreated chlamydia can lead to pelvic inflammatory disease (PID) and infertility. Chlamydia may also cause eye infection (trachoma) and pneumonia.
cholesterol: a waxy, fatty substance in animal tissue that is an essential component of cell membranes and nerve fiber insulation. There are three types of cholesterol in the blood: low-density lipoprotein (LDL), which is considered a risk factor for heart disease; high-density lipoprotein (HDL), which is considered protective against heart disease; and very low density lipoprotein.
cholesterolemia: See hypercholesterolemia.
CHOP: a cancer chemotherapy regimen that combines cyclophosphamide, hydroxyldaunomycin (doxorubicin, or Adriamycin), vincristine (Oncovin), and prednisone.
chromosome: a structure of compact, intertwined molecules of DNA, found in the nucleus of cells, which carry the cell's genetic information.
chronic: slow to develop, persisting over a long period, or recurring frequently.
Contrast with acute.
chronic fatigue syndrome (aka chronic fatigue immune dysfunction syndrome, acronym CFIDS): an illness of unknown etiology characterized by persistent fatigue, weakness, headache, joint and muscle pain, inability to concentrate, and impaired ability to function, normally for six months or longer.
CIN: See cervical intraepithelial neoplasia.
circumoral: around the mouth.
cirrhosis: a type of liver damage in which normal liver cells are replaced with fibrous scar tissue; causes include chronic viral hepatitis and heavy alcohol consumption. Compensated cirrhosis means that the liver is damaged but can still function; in decompensated cirrhosis, liver function is severely impaired and scar tissue may interfere with normal blood flow through the liver.
clade: a distinct strain of a microorganism. See also subtype.
clearance: the removal or elimination (e.g., of a drug or microorganism) from the body.
clinical: refers to the treatment of patients; a clinical observation is based on the observed condition of individuals and their symptoms, as distinguished from blood tests or other laboratory findings.
clinical trial (aka clinical study): a procedure for determining the effectiveness of a new therapy or treatment approach by administering the agent or method to participants under strictly controlled conditions. In many clinical trials, experimental agents are tested against older agents or against an inactive substance (placebo). The clinical trial process includes Phase I, II, and III trials, and Phase IV postmarketing evaluation.
clot: a sticky mass of coagulated blood cells and platelets.
clotting factor: a protein (e.g., prothrombin, factor VIII) that promotes blood coagulation.
CMV: See cytomegalovirus.
CNS: See central nervous system.
coagulation: clotting; the transformation of a liquid (e.g., blood) into a solid mass.
cobalamin (aka vitamin B12): See vitamin B.
codon: a sequence of three nucleotides that encodes the information for a particular amino acid; mutations at specific codon locations can confer resistance to certain drugs.
cofactor: a factor (e.g., substance, microorganism, environmental condition) that influences the progression of a disease or the action of a disease-causing agent.
cognition (adjective cognitive): the processes of thinking and learning; the higher mental functions.
cognitive impairment: reduction in mental functioning and ability to carry out tasks that require thinking, planning, and memory.
cohort: a group of individuals in a study who share a demographic, clinical, or other characteristic (e.g., age, study site).
coinfection: concurrent infection with more than one disease-causing organism; often refers to infection with both HIV and hepatitis C or B. Compare with superinfection.
colitis: inflammation of the colon.
collagen: a fibrous protein that makes up connective tissue; collagen injections may be used to treat facial lipoatrophy (wasting).
colon: the large intestine, extending from the small intestine to the rectum.
colonoscopy: examination of the large intestine using a narrow, flexible lighted instrument.
colony-stimulating factor (acronym CSF): a cytokine responsible for regulating the production of white blood cells; types include granulocyte colony-stimulating factor (G-CSF), granulocyte macrophage colony-stimulating factor (GM-CSF), and macrophage colony-stimulating factor (M-CSF).
colorectal: refers to the colon and rectum.
colostrum: breast fluid, produced prior to milk in the first days after delivery, that contains large amounts of proteins, calories, antibodies, and lymphocytes.
colposcopy: examination of the uterine cervix or anal canal using a lighted magnifying instrument (colposcope) to identify abnormal cell growth and, if necessary, remove a tissue sample for biopsy.
combination therapy: simultaneous administration of two or more drugs or other types of therapy.
Combivir: a combination pill containing the nucleoside reverse transcriptase inhibitor drugs AZT and 3TC.
community advisory board (acronym CAB): a group of community members (e.g., people with HIV/AIDS, care providers, advocates) who provide recommendations regarding clinical research.
Community Programs for Clinical Research on AIDS (acronym CPCRA): a community-based clinical trials network that conducts studies in community settings.
comparison trial: a type of clinical trial in which two or more experimental therapies are tested against each other or against existing therapies.
compartment: a separate structural portion (e.g., of the body or of a cell); a distinct area or part of the body, which may or may not have a discrete physical boundary; in pharmacology, an area of the body where a drug is metabolized.
compassionate use: release of an unapproved experimental drug by a manufacturer to individuals with a serious illness who are unable to participate in clinical trials. See also expanded access.
compensated cirrhosis: See cirrhosis.
complementary and alternative medicine (acronym CAM): any type of therapy that is not considered standard practice in a given culture. In the U.S., CAM includes traditional Chinese medicine, homeopathy, naturopathy, herbal medicine, and chiropractic methods. Complementary therapies are additional forms of treatment used as an adjunct to standard therapy, while alternative therapies are used instead of standard therapy.
complete blood count (acronym CBC): an inventory of the cellular components of whole blood, including red blood cells (including hematocrit and hemoglobin), various types of white blood cells (such as granulocytes and lymphocytes), and platelets.
compliance: See adherence.
computed tomography scan (aka computed axial tomography, aka CT scan, aka CAT scan): a method of visualizing the soft tissues of the body using X-rays.
concomitant: accompanied by or occurring at the same time; concomitant therapies are those that are used together.
concurrent: occurring at (or, for drugs, taken at) the same time.
condom: a sheath made of latex or polyurethane that is worn over the penis to prevent pregnancy and/or the spread of HIV and other sexually transmitted infections; the “female condom” (Reality) is an internal pouch worn inside the vagina or anus.
condylomata acuminata: genital or anal warts caused by infection with a strain of the human papillomavirus (HPV); warts may appear as tiny white spots or as larger tumors or masses. The condition is typically sexually transmitted, and may be particularly aggressive in immunocompromised people.
cone biopsy (aka conization): removal of a cone-shaped wedge from the bottom of the uterine cervix to remove lesions and/or to provide a tissue sample for biopsy.
confidence interval: a statistical measure of the likelihood that an experimental result is true and not the result of chance alone; confidence improves as larger numbers of participants are included in a trial.
confounder: a factor that can influence a trial or experiment, leading to unexpected outcomes that improperly skew the results.
congenital: present from the time of birth.
congestive heart failure: heart dysfunction that leads to a buildup of fluid in the body.
conserved region: part of a microorganism that varies little from individual to individual; such regions are preferred for vaccines since they confer broader protection against various strains and subtypes.
contraception: birth control; contraceptives are agents or methods that prevent conception or successful gestation.
contraindication: any circumstance or condition that makes a drug or other therapy inadvisable.
control arm: See controlled trial.
controlled trial: a clinical trial in which a group receiving an experimental drug or other therapy (the experimental arm) is compared with a group not receiving that therapy (the control arm). In a placebo-controlled trial, the control arm receives an inactive substance or mock therapy (placebo); in an active control trial, the control group is given an existing standard therapy. Compare with uncontrolled trial.
core: the internal portion of the HIV viral particle.
coreceptor: a second cell surface receptor required for entry by a pathogen into a host cell or for initiation of a biological process; HIV requires both the CD4 receptor and a coreceptor (CCR5 or CXCR4) to enter a cell.
coronary: relating to the arteries that supply the heart muscle.
coronary artery disease (aka coronary heart disease): damage to or blockage of the coronary arteries that provide blood to the heart muscle.
corroborate: to confirm.
cortex (adjective cortical): the outer part of an organ (e.g., cerebral cortex, adrenal cortex).
corticosteroid: one of a group of steroid hormones produced by the cortex of the adrenal gland (e.g., cortisone, aldosterone) or manufactured synthetically (e.g., prednisone); corticosteroids have anti-inflammatory and immunosuppressive properties and are used to treat a variety of conditions. See also glucocorticoid.
cortisol: a steroid hormone secreted by the adrenal cortex as part of the body's response to stress; synthetic cortisol (hydrocortisone) is used to reduce inflammation and lessen allergic reactions.
CPCRA: See Community Programs for Clinical Research on AIDS.
C-peptide: a protein fragment produced during the synthesis of insulin.
C-reactive protein: a protein often found in the blood of people with inflammatory diseases; elevated levels are a risk factor for cardiovascular disease.
creatinine phosphokinase (acronym CPK): an enzyme essential for muscle contraction; elevated blood CPK may indicate muscle disease or damage (including myocardial infarction, or heart attack).
Crixivan: brand name of indinavir.
cross-immunity: a state in which immunity to one organism serves to protect an individual against a different but related organism.
crossover: a trial design in which the therapy given to different arms is switched during the course of the trial.
cross-reactivity: a process by which an antibody responds to an antigen other than that which originally stimulated its production.
cross-resistance: the mechanism by which development of resistance to one drug also confers resistance to another, usually similar, agent.
cross-tolerance: a situation in which tolerance to one drug carries over to another related drug, so that the similar drug has reduced effects. See also tolerance.
cryotherapy (aka cryosurgery): the use of liquid nitrogen to freeze an abnormal lesion; cryotherapy is sometimes used to induce scar formation to prevent further spread of abnormal cells.
cryptococcosis: an infection caused by a fungus, typically Cryptococcus neoformans, found in soil and bird feces; a common manifestation is cryptococcal meningitis, an inflammation of the membranes surrounding the brain and spinal cord.
cryptosporidiosis: a disease caused by the protozoan Cryptosporidium parvum, which is transmitted by contact with animal feces, ingestion of contaminated food or water, or oral-anal sexual contact (rimming). Cryptosporidiosis can cause severe, chronic diarrhea; weight loss; and lymphadenopathy.
CT scan: See computed tomography scan.
CTL: See cytotoxic T lymphocyte.
culture: a method of growing a microorganism or living cells or tissue in vitro in a medium that promotes growth.
cunnilingus: oral sex on a woman; sexual contact between one person's tongue or mouth and a woman's vulva, clitoris, or vagina.
Cushing's syndrome: a disorder caused by excessive secretion of the adrenal hormone cortisol; the syndrome is characterized by accumulation of fat around the abdomen, and its symptoms in some respects resemble those of lipodystrophy.
cutaneous: refers to the skin.
CXCR4: a protein found on certain cells that acts as a receptor for the chemokine SDF-1; CXCR4 functions as a coreceptor that enables certain strains of HIV to enter cells.
CXCR4 blocker: See entry inhibitor.
Cyclospora: a parasite that resembles Cryptosporidia and can also cause severe diarrhea.
CYP3A4: See cytochrome.
CYP450: See cytochrome.
cystitis: inflammation of the urinary bladder.
cytochrome (acronym CYP450): a system of enzymes (e.g., CYP3A4) that metabolize many drugs in the liver; drug interactions may occur when one agent induces or inhibits CYP450 activity, thus speeding up or slowing down the metabolism of other drugs.
cytokine: an intercellular hormone produced by immune cells that acts as a chemical messenger to facilitate communication among immune cells and between immune cells and the rest of the body; cytokines (e.g., interferon, interleukins, tumor necrosis factor) coordinate and regulate many aspects of immune response, including antibody production, migration of phagocytes, and activation of cytotoxic T lymphocytes.
cytology: the study of the structure, function, and pathology of cells.
cytolysis (adjective cytolytic): destruction of a cell by rupturing.
cytomegalovirus (acronym CMV, aka human herpesvirus 5): a herpesvirus that often infects healthy individuals without causing symptoms; in immunocompromised individuals (usually those with fewer than 50 CD4 cells/mm3), CMV may cause serious disease, including retinitis (inflammation of the retina), pneumonia, colitis (inflammation of the large intestine), and encephalitis (inflammation of the brain).
cytopathology (adjective cytopathic): disease, disorders, or destruction of cells.
cytopenia: reduced number of cells, in particular blood cells.
cytoplasm: the gel-like substance that composes cells and lies outside the cell nucleus.
cytoprotective: an agent that protects cells from damage.
cytosine: one of the pyrimidine nucleic acid bases that make up nucleotides, the building blocks of DNA and RNA.
cytotoxic (noun cytotoxicity): poisonous or harmful to cells.
cytotoxic T lymphocyte (acronym CTL, aka killer T cell): a type of white blood cell that bears the CD8 surface marker, and targets and kills cancerous cells and cells infected with viruses; the action of CTLs is coordinated by CD4 cells via the production of cytokines.
A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z