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.
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T cell (aka T lymphocyte): an immune system white blood cell that matures in the thymus and carries out the cell-mediated (Th1) immune response. There are three major types of T cells: CD4 helper T cells, CD8 suppressor T cells, and CD8 killer T cells (cytotoxic T lymphocytes or CTLs). Compare with B cell.
T helper cell: See CD4 cell.
T suppressor cell: See CD8 cell.
T-20 (generic name enfuvirtide, brand name Fuzeon): an entry inhibitor drug approved for use as part of combination antiretroviral therapy to treat HIV disease.
T4 cell: See CD4 cell.
T8 cell: See CD8 cell.
tachycardia: rapid heartbeat.
tat: transactivator of transcription, an HIV gene that plays a role in viral replication; also refers to the protein (Tat) produced by this gene.
Tat inhibitor: a drug that inhibits HIV replication by interfering with the Tat protein.
TB: See tuberculosis.
TCM:
See traditional Chinese medicine.
TDM: See therapeutic drug monitoring.
tenofovir DF (acronym TDF, brand name Viread): a nucleotide reverse transcriptase inhibitor drug approved for use as part of combination antiretroviral therapy to treat HIV disease.
teratogenic (noun teratogenicity): capable of causing birth defects, or malformations of a fetus.
testes (singular testis): male gonads (sex organs) that produce sperm.
testosterone: a steroid hormone produced by the testes and adrenal glands. Testosterone is required for sperm production and the development of male secondary sexual characteristics; it also promotes the synthesis of lean muscle mass and plays a role in sexual arousal in both men and women.
Th1 immune response: one of the branches of the immune system; the Th1 response is carried out by a subset of CD4 and CD8 lymphocytes that secrete cytokines such as interleukin-2, interferon-gamma, and TNF-alpha, and promote cell-mediated immunity (the action of cytotoxic T lymphocytes, natural killer cells, and macrophages). The Th1 response is especially effective against cells infected with viruses and cancerous cells. Compare with Th2 immune response.
Th2 immune response: one of the branches of the immune system; the Th2 response is carried out by a subset of CD4 and CD8 lymphocytes that secrete a variety of interleukin cytokines and promote humoral immunity (antibody production by B cells). The Th2 response is especially effective against extracellular microorganisms such as bacteria. Compare with Th1 immune response.
thalamus: a cluster of nerve cell bodies deep in the brain that acts as a relay station for sensory (especially pain and pleasure) information and plays a role in arousal.
therapeutic drug monitoring (acronym TDM): the measurement of plasma drug concentrations in an effort to provide the most effective dosage with the least possible toxicity; TDM may be used to help guide decisions regarding changes in drug dosing.
therapeutic vaccine: See vaccine.
therapeutic window (aka therapeutic ratio): the range of doses of a drug that achieve clinical efficacy but do not cause intolerable side effects; the difference between the minimum and maximum effective doses.
thiamine (aka vitamin B1): See vitamin B.
thrombocyte (aka platelet): a type of blood cell that facilitates normal blood clotting.
thrombocytopenia: an abnormally low number of platelets, which may result in abnormal bleeding and easy bruising.
thrombopoietin (acronym TPO): a cytokine that stimulates the production of platelets.
thrombosis: formation or presence of a clot (thrombus) within a blood vessel.
thrush: See oral candidiasis.
thymic factor: a hormone or cytokine (e.g., thymosin-alpha1, thymic humoral factor, thymomodulin, thymopentin, thymostimulin) produced by the thymus gland, or a synthetic agent with a similar effect, that is involved in the regulation of immune function.
thymine: one of the pyrimidine nucleic acid bases that make up nucleotides, the building blocks of genetic material; thymine is a component of DNA, but is replaced by uracil in RNA.
thymus (adjective thymic): a lymphoid organ located at the base of the neck that plays an important role in immune function; the gland is the site of T cell maturation and differentiation -- where the cells learn to recognize antigens -- and also produces several hormones (thymic factors) involved in immune regulation. The thymus is a source of T cell production in fetuses and is active in children, but it atrophies with age and is typically less active in adults.
thyroid gland: an endocrine gland at base of the neck that produces several hormones that plays a role in regulating growth and metabolism.
tid: three times a day.
TMP-SMX: See trimethoprim-sulfamethoxazole.
TNF: See tumor necrosis factor.
tocopherol: See vitamin E.
tolerability: the degree to which a drug or other agent produces adverse side effects.
tolerance: a condition in which the body becomes accustomed to an agent (e.g., a drug) so that the previous dose no longer produces the desired effect.
topical: refers to the surface of the skin; a medication applied to the skin.
toxic (noun toxicity): poisonous or harmful; often used to refer to drug side effects.
toxic epidermal necrolysis: a potentially life-threatening condition, often due to a drug reaction, characterized by blistering and sloughing of the outer layer of the skin and mucous membranes. See also Stevens-Johnson syndrome.
toxicology: the study of the harmful effects of substances on the body.
toxin: a harmful or poisonous agent.
toxoplasmosis: an opportunistic disease caused by the Toxoplasma gondii protozoan, found in undercooked meat and cat feces; a common manifestation is toxoplasmic encephalitis, characterized by brain swelling, confusion, lethargy, and possible coma.
traditional Chinese medicine (acronym TCM): an ancient Asian system of healing that focuses on achieving internal balance; TCM practitioners use methods such as acupuncture, moxibustion, herbal formulas, and exercises such as t?ai chi and qi gong to restore the flow of qi (vital energy) within the body.
trans-: prefix meaning across, through, or between.
transaminase: See aminotransferase.
transcription: the first step in protein synthesis and replication; genetic information encoded in DNA is copied to messenger RNA, which is used as a template for the production of new proteins.
transcription mediated amplification (acronym TMA): a recently developed, highly sensitive viral load test.
transformation zone (aka squamo-columnar junction): the area of the cervix or anal canal where squamous and columnar epithelial cells meet and overlap; a common site for intraepithelial neoplasia.
transient: short-lived; not permanent.
transmission: spread of an infectious organism from one individual to another.
treatment arm: a group of participants in a research trial who all receive the same treatment. Compare with control arm.
treatment failure: inability of a medical therapy to achieve the desired result; in HIV, treatment failure typically refers to inability to reduce or completely suppress viral load.
treatment-experienced: an individual who has previously been treated for a particular condition. Contrast with treatment-naive.
treatment-naive: an individual who has not previously been treatment for a particular condition. Contrast with treatment-experienced.
trial: an experiment involving the collection, analysis, and interpretation of data. See also clinical trial.
tricyclic antidepressant (acronym TCA): a class of commonly used antidepressants (e.g., imipramine [Tofranil], amitriptyline [Elavil], nortriptyline [Pamelor]) that increase levels of the neurotransmitters serotonin and norepinephrine.
triglyceride: a combination of glycerol and fatty acid that circulates in the blood; elevated triglyceride levels, particularly when accompanied by elevated low-density lipoprotein (LDL) cholesterol, have been correlated with the development of cardiovascular disease.
trimethoprim-sulfamethoxazole (acronym TMP-SMX, brand name Bactrim, brand name Septra): an antibiotic drug combination used to prevent and treat Pneumocystis carinii pneumonia (PCP); it is also effective against several other bacterial infections.
Trizivir: a combination pill containing the nucleoside reverse transcriptase inhibitor drugs AZT, 3TC, and abacavir.
tropism: 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.
trough concentration (aka Cmin): the lowest concentration of a drug in the blood between dosages. Contrast with peak concentration.
truncal obesity: See central obesity.
T-tropic: refers to strains of HIV that preferentially infect T lymphocytes. Compare with M-tropic.
tuberculin skin test (aka Mantoux test, aka PPD test): a test that uses an injection of purified protein derivative of tuberculin to test for tuberculosis infection; a positive reaction, characterized by induration (hard swelling) at the injection site, indicates exposure to Mycobacterium tuberculosis.
tuberculosis (acronym TB): a potentially fatal infectious disease caused by Mycobacterium tuberculosis; TB that typically affects the lungs, but may also occur in other organs (extrapulmonary TB). Multidrug-resistant tuberculosis (MDRTB) is resistant to several standard drugs and requires more aggressive therapy.
tumor: an abnormal tissue mass, or neoplasm; tumors may be either benign or malignant (cancerous).
tumor necrosis factor (acronym TNF, aka cachectin, acronym TNF): a cytokine produced by several types of activated white blood cells that destroys cancerous cells and induces inflammation; TNF has several other effects in the body, including the promotion of wasting.
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