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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radiation therapy (aka radiotherapy): the use of radiation to treat disease, especially cancer.
radiography: the use of pictures taken with X-rays, for example, for diagnosis.
radioimmunoassay: a procedure for detecting antigens or antibodies using radioactive-labeled proteins.
radiology: a medical specialty concerned with the use of radiation to diagnose and/or treat disease.
randomized trial: a clinical trial in which subjects are assigned by chance to different treatment or control arms; randomization is done in an attempt to cancel out the influence of individual subject characteristics and other factors that are not under study.
RANTES: a chemokine that, in association with MIP-1 alpha and MIP-1 beta, binds with the CCR5 cell surface receptor and inhibits the entry of HIV into a host cell.
RBC: See erythrocyte.
reagent: an agent used to promote a chemical reaction.
rebound: See viral rebound.
receptor: a specific binding site on a cell's surface or interior. When chemical messengers bind to receptors, various cellular functions are activated or inhibited. Viruses enter host cells by fusing with receptors on the cell surface, and many drugs exert their effects by binding to receptors and altering cellular function.
recombinant: produced by genetic engineering.
recommended daily allowance (acronym RDA): the amount of a nutrient that is required each day to avoid deficiency.
reconstitution: rebuilding and restoring to functionality (e.g., immune reconstitution); restoration of a compound to its original state.
recrudescence: a new outbreak or renewal of active replication of a pathogenic organism after a period of inactivity.
rectum (adjective rectal): the lower part of the large intestine where feces are stored.
recurrent: returning or occurring repeatedly.
red blood cell: See erythrocyte.
refractory: resistant to treatment.
regeneration: regrowth.
regimen: a specific drug combination and how it should be taken.
regression: a return to a previous condition; shrinking (e.g., of a tumor).
regression analysis: a statistical technique used to analyze the relationship between variables; a technique used to predict the probability of an outcome as a function of independent variables.
regulatory gene: HIV genes (nef, rev, tat) that control viral replication in infected cells.
relapse: recurrence of disease symptoms following a period of improvement.
relative risk (acronym RR): a statistical measure of the comparative risk of developing a disease or condition; RR is the chance that a person with a specific risk factor (e.g., older age, exposure to a drug) will develop a condition compared with the chance that a person without that risk factor will develop the same condition.
remission: abatement in the severity of disease symptoms; a period during which symptoms are reduced or eliminated.
renal: refers to the kidneys.
replication: multiplication or reproduction.
Rescriptor: brand name of delavirdine.
reservoir: a site (e.g., the brain, resting CD4 cells) where an infectious agent hides in the body, often in an inactive state.
resistance: the mutation of a microorganism in such a way that it loses its sensitivity to a drug; a resistant organism can function and replicate despite the drug’s presence. Contrast with susceptible. See also cross-resistance.
resistin: a hormone produced by fat cells that inhibits the action of insulin.
resorption: the process of dissolving and assimilating a substance (e.g., bone tissue).
respiratory: refers to the process of breathing.
retina: the light-sensitive tissue at the back of the eyeball that transmits visual impulses via the optic nerve to the brain.
retinitis: inflammation of the retina, potentially resulting in the loss of vision.
retinopathy: disease of the retina.
retrospective study: a study based on medical records, looking backward in time at events that happened in the past; a retrospective cohort study uses the records of a specific group of subjects. Compare with prospective study.
Retrovir: brand name of AZT.
retrovirus: a class of viruses that carry their genetic material in the form of RNA and use the reverse transcriptase enzyme to convert RNA into DNA in a host cell; the retrovirus family includes spumaviruses, oncoviruses, and lentiviruses such as HIV.
reuptake: resorption and recycling, especially of neurotransmitters.
rev: an HIV gene necessary for the construction of new virus particles; also refers to the protein (Rev) produced by this gene.
reverse transcriptase (acronym RT): a viral enzyme that allows a retrovirus to convert its genetic material from RNA to DNA, which is then integrated into the chromosomes of the host cell.
reverse transcriptase inhibitor (acronym RTI): a drug that blocks retroviral replication by interfering with the reverse transcriptase enzyme; RTI drugs include nucleoside reverse transcriptase inhibitors (which mimic the building blocks of genetic material) and non-nucleoside reverse transcriptase inhibitors (which bind to reverse transcriptase and prevent it from converting RNA to DNA).
reverse transcriptase polymerase chain reaction as: See polymerase chain reaction (PCR) assay.
Reyataz: brand name of atazanavir.
rheumatology (adjective rheumatological): the medical specialty concerned with disorders of the joints.
rhinitis: inflammation of the nasal membranes characterized by sneezing, runny nose, and watering eyes; a common manifestation of allergic reactions.
ribavirin (brand name Rebetol, brand name Copegus): an antiviral drug used in combination with interferon to treat chronic hepatitis C.
riboflavin (aka vitamin B2): See vitamin B.
ribonuclease: an enzyme that cleaves RNA.
ribonucleic acid (acronym RNA): a single-stranded molecule made up of a sequence of four chemical building blocks (nucleotides) -- adenine, cytosine, guanine, and uracil -- that encodes genetic information. In most organisms, DNA is translated into messenger RNA (mRNA), which controls the production of new proteins. Retroviruses such as HIV carry their genetic information in the form of RNA; the presence of HIV RNA in the blood plasma indicates that the virus is actively replicating. See also deoxyribonucleic acid.
ribonucleotide: a structural component or building block of RNA. See nucleotide.
ribonucleotide reductase: an enzyme that converts ribonucleotides into deoxyribonucleotides, the building blocks of DNA; ribonucleotide reductase inhibitors (e.g., hydroxyurea) interfere with the action of this enzyme.
rimming (aka analingus): oral-anal sex; sexual contact between one person's tongue and/or mouth and another person’s anus.
risk/benefit ratio: a measurement used to evaluate whether potential benefits outweigh potential risks.
ritonavir (brand name Norvir): a protease inhibitor drug approved for use as part of combination antiretroviral therapy to treat HIV disease; ritonavir is commonly used in small doses to boost levels of other protease inhibitors.
RNA: See ribonucleic acid.
rollover trial: a follow-up study that allows people who successfully completed an original trial protocol to continue taking an experimental therapy.
RT-PCR: See polymerase chain reaction (PCR) assay.
Rx: abbreviation for prescription medication.
Ryan White C.A.R.E. Act: U.S. federal legislation that provides funding for services for people with HIV/AIDS.
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