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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p24: a core protein of HIV produced by the gag gene; the presence of p24 in the blood indicates that HIV is actively replicating.
PACTG: See AIDS Clinical Trials Group.
palate: the roof of the mouth.
palliative: offering symptomatic relief and comfort care (e.g., alleviation of pain) rather than a cure.
palpitation: the sensation of a rapid or irregular heartbeat.
pancreas: a digestive gland in the abdominal cavity that is responsible for secreting digestive enzymes; small glands in the pancreas (the Islets of Langerhans) produce insulin.
pancreatitis: inflammation of the pancreas.
pancytopenia: an abnormally low level of all types of blood cells, typically due to bone marrow damage.
pandemic: a widespread disease outbreak affecting the population of an extensive area of the world. See also epidemic.
Pap smear (aka Papanicolaou smear): a procedure in which a sample of cells is taken from the uterine cervix or anal canal, prepared on a slide, and examined under a microscope for abnormal cell growth; an abnormal Pap smear suggests increased risk of cancer.
papillomavirus: See human papillomavirus.
papule: a small, raised bump on the skin or mucous membrane.
parasite: an organism that lives in and derives nourishment from the body of a host; human parasites include fungi, bacteria, protozoans, and helminths (worms).
parenteral: given by injection or infusion, bypassing the gastrointestinal tract; parenteral nutrition refers to nutrients delivered directly into the bloodstream.
paresthesia: an abnormal physical sensation such as numbness, prickling, or tingling.
passive immunity: immunity acquired via transfer of antibodies, either from mother to fetus or by injection. Contrast with active immunity.
passive immunization: See immunization.
pathogen (adjective pathogenic): any disease-causing agent, especially a microorganism.
pathogenesis: the development of disease.
pathogenic: able to cause disease.
pathology (adjective pathological): the study of disease, focusing on causes, development, and progression.
pathophysiology: the functional changes that accompany a disease.
patient-year (aka person-year): a shorthand term used by epidemiologists to make comparisons; its value is determined by multiplying the number of individuals by the number of years. For example, one person followed for ten years or ten persons followed for one year both equal ten patient-years.
PCP:
See Pneumocystis carinii.
PCR: See polymerase chain reaction (PCR) assay.
peak concentration (aka Cmax): the highest concentration of a drug in the blood after dosing.
Contrast with trough concentration.
pediatrics: the medical specialty concerned with the development, care, and treatment of children from birth through adolescence.
pegylated interferon (brand name Pegasys, brand name Peg-Intron): a formulation of interferon-alpha that lasts longer in the body and can be injected less often than conventional interferon; pegylated interferon is standard therapy for hepatitis C, and is also used to treat hepatitis B.
pelvic exam: examination of the organs of the female reproductive system, including the vagina, cervix, uterus, and ovaries.
pelvic inflammatory disease (acronym PID): infection of the upper female reproductive tract including the uterus, fallopian tubes, and ovaries; PID is often the result of untreated chlamydia or gonorrhea, and may lead to scarring, infertility, ectopic pregnancy, and death.
pelvis (adjective pelvic): the large cup-shaped bone at the base of the spine.
peptide: a short chain of amino acids linked by peptide bonds; longer chains are generally called proteins.
peptide T: a peptide composed of eight amino acids; peptide T has been studied as an anti-HIV therapy and for the treatment of AIDS-related dementia.
percutaneous: through the skin.
peri-: prefix meaning around or surrounding.
perianal: refers to the area surrounding the anus.
perinatal: refers to the period around the time of birth.
perinatal transmission: See mother-to-child transmission.
periodontal disease (aka periodontitis): an inflammatory disease of the gum tissues that surround and support the teeth; periodontal disease may begin as gingivitis (gum inflammation) and progress to more serious disease characterized by erosion of the gums and bone supporting the teeth.
peripheral: located at the periphery or away from the center.
peripheral blood mononuclear cell (acronym PBMC): a single-nucleus white blood cell (e.g., monocyte) that circulates in the blood.
peripheral nervous system: the portion of the nervous system outside the brain and spinal cord.
peripheral neuropathy: damage to the peripheral nerves, usually involving the feet, hands, and sometimes the legs, arms, and face; types include distal symmetrical neuropathy and inflammatory demyelinating polyneuropathy. Symptoms may include numbness, tingling, or burning sensations, pain, and weakness.
peritoneum: the thick membrane that lines the abdominal cavity and covers the visceral organs.
peritonitis: inflammation of the peritoneum.
permeable: allowing substances (especially liquids) to pass through.
person-year: See patient-year.
PET scan: See positron emission tomography (PET) scan.
p-glycoprotein: a plasma membrane protein that pumps drugs and other substances out of cells.
pH: a logarithmic scale used to describe the acidity or alkalinity of a solution; a measure of the hydrogen concentration of a solution. Water has a neutral pH of 7; a pH below 7 is acidic, while a pH above 7 is alkaline (basic).
phagocyte: a scavenger white blood cell (e.g., neutrophil, basophil, eosinophil, monocyte, macrophage) that engulfs and destroys dead cells, bacteria, and other debris by a process known as phagocytosis.
pharmaceutical: refers to the development and manufacture of drugs; a manufactured drug.
pharmacodynamics: the biochemical and physiological effects of drugs and their mechanisms of action in the body.
pharmacokinetics: how drugs are processed and used in the body, including absorption, metabolism, distribution to tissues, and elimination.
pharmacology (adjective pharmacological): the science of drugs and how they work.
pharyngitis: "sore throat"; inflammation of the pharynx (throat).
pharynx (adjective pharyngeal): the throat; the upper part of the gastrointestinal tract between the oral cavity (mouth) and the esophagus.
Phase I trial: the first stage of human testing of a new drug; these trials evaluate drug pharmacokinetics, safety, tolerability, and optimal doses, typically in a small number of healthy volunteers (typically 10-100).
Phase II trial: the second stage of the evaluation of a new drug in humans; these trials evaluate drug safety and preliminary efficacy (effectiveness) in a larger number of participants (up to several hundred). Phase II trials may be divided into Phase IIa (pilot trials in individuals with the disease to be treated) and Phase IIb (controlled efficacy trials).
Phase III trial: the third stage of human drug testing; these trials are designed to determine the effectiveness of a treatment, often by comparing it to an existing standard therapy or a placebo, in a large numbers of participants (typically hundreds or thousands).
Phase IV trial: postmarketing studies conducted after a new treatment is approved and offered for sale; these trials provide additional information about safety and efficacy in large numbers of individuals under “real world” conditions.
phenotype (adjective phenotypic): visible characteristics or behavior that result from the interaction of an organism’s genetic "blueprint" (genotype) and the environment; phenotypic resistance testing determines whether an organism is susceptible to a specific drug in a test tube.
Compare with genotype.
phosphorylation: the addition of a phosphate group to a compound by an enzyme.
photosensitivity: increased sensitivity to light, which may lead to easy sunburning.
Physicians’ Desk Reference (acronym PDR): a book listing prescription drugs and their indications.
PI: See protease inhibitor.
PID: See pelvic inflammatory disease.
pituitary gland: a small gland in the brain that produces several hormones that regulate bodily functions via the action of other endocrine glands.
placebo: an inactive substance (e.g., a "sugar pill") or mock therapy; new experimental therapies are compared with placebos is many clinical trials. The placebo effect refers to changes (e.g., improved symptoms) attributable to the treatment process itself as opposed to the therapeutic value of the agents or methods used, likely due to the expectations of the patient.
placebo-controlled trial: See controlled trial.
placenta: the vascular organ that connects the fetus to the mother's uterus, allowing the exchange of oxygen and nutrients, and the removal of waste products.
plaque: an accumulation of material (cholesterol, cellular debris, mineral deposits) on the inner surface of arteries; a film of bacteria, food debris, and other materials on the teeth that promotes tooth decay.
plasma: the straw-colored fluid portion of circulating blood that carries blood cells and nutrients throughout the body, removes metabolic wastes, and is a medium for chemical communications between different parts of the body.
plasma cell: a type of immune cell that develops from B cells and produces antibodies.
plasmapheresis: a procedure in which whole blood is removed from the body, selected components are extracted, and the remaining blood is returned to the circulation.
platelet: See thrombocyte.
pleuritis: inflammation of the pleura, or linings of the lung.
PML: See progressive multifocal leukoencephalopathy.
PMS: See premenstrual syndrome.
PMTCT: prevention of mother-to-child transmission.
Pneumocystis carinii (adjective PCP): a life-threatening type of pneumonia caused by a protozoan. PCP is typically only seen in people with compromised immune systems (i.e., a CD4 cell count below 200 cells/mm3); it is much less common in people with HIV since the advent of HAART.
pneumonia: an inflammatory condition of the lungs in which they become obstructed with fluid, causing difficult breathing and possibly suffocation.
pneumonitis: lung inflammation.
po: given by mouth (from the Latin per os).
pol: the HIV gene that encodes the virus' replicative enzymes (protease, integrase, reverse transcriptase); also refers to the protein (Pol) produced by this gene.
poly-: prefix meaning many.
polylactic acid (brand name New-Fill): a synthetic compound injected into the cheeks for cosmetic treatment of facial lipoatrophy (wasting) and other imperfections.
polymerase: an enzyme that cleaves polymers, chemical compounds formed by the linkage of molecular pieces.
polymerase chain reaction (PCR) assay: a highly sensitive test that can detect small amounts of genetic material (DNA or RNA) in a blood or tissue sample by using an amplification technique to multiply existing DNA or RNA so that it can more easily be detected.
polymerase inhibitor: an agent that inhibits viral replication by interfering with the polymerase enzyme.
polymorphonuclear leukocyte (acronym PMNL): a type of white blood cell (e.g., neutrophil) containing more than one nucleus; PMNL are phagocytes (scavenger cells) important in immune defense, particularly against cell-free organisms such as fungi.
polyneuropathy: a type of peripheral neuropathy that involves damage to multiple nerves.
polyprotein: a long thread of proteins produced during viral replication; the HIV polyprotein is broken down by the protease enzyme into smaller components, which are then assembled into new virus particles.
polyradiculopathy: a type of peripheral neuropathy characterized by the inflammation of nerve roots.
polyvalent vaccine: a vaccine created from several different strains of a virus.
poppers: See nitrite inhalant.
positron emission tomography (PET) scan: an imaging method in which a radioactive substance is injected into the bloodstream and a scanner is used to measure cerebral blood flow in different parts of the brain.
post hoc: after the fact.
postexposure prophylaxis (acronym PEP): drugs given immediately following exposure to an infectious organism in an attempt to prevent the infection from taking hold in the body.
postmarketing study: See Phase IV trial.
postpartum: the period following childbirth.
potassium: a mineral necessary for the maintenance of bodily homeostasis.
potentiation: an increase in activity or effectiveness; an interaction between drugs that results in a synergistic effect.
power: a statistical term used to describe the ability of an experiment or trial to return a reliable result; generally, the power of a clinical trial increases as more subjects are included or as it continues for a longer period.
poxvirus: one of a large family of viruses (e.g., smallpox) that typically cause skin eruptions.
PPD test: See tuberculin skin test.
preclinical research: testing of an experimental drug in the laboratory or in animals prior to human testing.
pre-existing condition: a medical problem that existed before a specific date.
premalignant: refers to cells that display abnormal growth and development and may be an early stage of cancer.
premature rupture of membranes: See rupture of membranes.
premenstrual syndrome (acronym PMS): a set of symptoms occurring before or during the menstrual period, characterized by cramps, fatigue, bloating, and mood changes.
prenatal: the period preceding birth, during which the fetus develops in the uterus.
presumptive diagnosis/treatment: diagnosis or treatment based on an assumed diagnosis, prior to receiving confirmatory laboratory test results.
prevalence (aka prevalence rate): the number of existing cases of a disease or condition in a specific population during a given period; the prevalence rate is determined by dividing the number of people with the condition by the total population. Compare with incidence.
preventive vaccine: See vaccine.
primary (acute) HIV infection: the initial stage of infection with HIV, prior to the development of antibodies; primary HIV infection may be accompanied by acute retroviral syndrome, characterized by flu-like symptoms such as fever, malaise, enlarged lymph glands, sore throat, skin rash, and muscle or joint aches.
primary care: basic medical care; the first line of medical management of a condition.
primary infection: the initial introduction of an infectious organism into the body.
primary isolate: HIV taken from an infected individual, as opposed to that grown in a laboratory.
primary prophylaxis: a treatment intended to prevent the first occurrence of an infection or disease. Compare with secondary prophylaxis.
prime-boost: a strategy of administering one vaccine dose (or one type of vaccine) to elicit certain immune responses, followed by or together with a booster, a second vaccine dose (or second type of vaccine). The prime-boost strategy may be used to strengthen the initial immune response or to elicit different types of immune response (e.g., humoral and cell-mediated.
PRN: administered as needed (from the Latin pro re nata).
proctitis: inflammation of the mucous membranes of the rectum.
proctoscopy: examination of the rectum and lower end of the colon with a lighted instrument. See also sigmoidoscopy.
prodromal symptoms (aka prodrome): early symptoms or signs that indicate the onset of a disease or a recurrent outbreak.
prodrug: an inactive form of a drug that is converted within the body to a usable or active form.
progesterone: a female steroid hormone with anti-estrogen effects; progesterone prepares the uterus for the development of the fertilized ovum and maintains the uterus throughout pregnancy; synthetic progesterone is used as a contraceptive.
progestin: a hormone produced by the corpus luteum, placenta, or adrenal cortex that has progesterone-like effects; synthetic progestin is used as a contraceptive.
prognosis (adjective prognostic): a forecast of the probable course or outcome of a disease.
programmed cell death: See apoptosis.
progression: advancement or worsening of a disease.
progressive multifocal leukoencephalopathy (acronym PML): a rapidly progressing, often fatal brain disease caused by the JC papovavirus; PML infects oligodendrocytes (support cells in the brain) and leads to deterioration of the brain’s white matter.
proinflammatory cytokine: a chemical messenger (e.g., IL-6, tumor necrosis factor) that promotes an inflammatory immune response.
proliferation: rapid multiplication or replication.
prophylactic vaccine: See vaccine.
prophylaxis: therapy 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; a prospective cohort study follows a specific group of people over a period of time. Compare with retrospective study.
prostate gland: a large gland in males, located at the base of the urethra, that manufactures the liquid portion of semen.
protease: an enzyme that cuts proteins; the HIV protease cleaves the large precursor proteins produced from viral RNA into the component parts (e.g., enzymes and structural proteins) that are then assembled into new viral particles.
protease inhibitor (acronym PI): a drug (e.g., saquinavir, ritonavir, indinavir, nelfinavir, amprenavir, lopinavir) that blocks the action of the HIV protease enzyme, thereby preventing viral replication.
protease-sparing regimen: combination highly active antiretroviral therapy that does not include a protease inhibitor.
protein: a complex organic compound consisting of chains of amino acids folded in specific configurations; proteins are the building blocks of cells and organic substances such as hormones and enzymes.
proteinuria: the abnormal presence of protein in the urine.
prothrombin: a protein synthesized by the liver that is necessary for proper blood clotting; prothrombin time (PT) is a measure of blood clotting time.
protocol: a plan that states the specifics of a clinical trial, such as the hypothesis to be tested, drug(s) to be used, method(s) of administration, length of the trial, endpoints, and characteristics of participants (enrollment criteria).
protozoan: an acellular or one-celled microorganism, several of which can cause disease in humans.
provirus: a state in which viral DNA has been inserted into the chromosomes of the host cell; proviral DNA refers to viral DNA that is integrated into a host cell’s genetic material.
proximal renal tubular dysfunction (acronym PRTD): a disorder of the small tubes in the kidney that filter urine.
pruritus (adjective pruritic): itchiness.
pseudomembrane: a tough, thick material on a mucosal or skin surface; a false membrane or covering.
pseudomembranous candidiasis: See oral candidiasis.
pseudovirion: a particle that resembles a virus but cannot replicate due to a lack of genetic material.
psychiatry: the branch of medicine concerned with mental illness.
psychoactive: affecting the mind, or mood.
psychoneuroimmunology: the study of how mental state and neurological and hormonal factors affect the functioning of the immune system.
psychosis: a major mental disorder (e.g., schizophrenia, bipolar disorder), often characterized by delusions, that affects the ability to function normally on a daily basis.
psychosocial: refers to mental health and social conditions, or factors that affect psychological or social well-being .
psychotherapy: treatment of mental problems with nonmedical therapies, in particular counseling.
psychotropic: an agent (e.g., thorazine) that affects psychic or mental functioning or behavior.
pulmonary: refers to the lungs.
punch biopsy: the removal of a small piece of tissue from the skin or mucous membrane for diagnostic analysis.
purine: one of the two types of nucleotide bases that make up DNA and RNA; the purine bases are adenine and guanine. See also pyrimidine.
purpura: a purplish discoloration due to bleeding underneath the skin.
purulent: characterized by the accumulation of pus.
pus: a thick, greenish-yellow fluid composed of dead white blood cells, killed microorganisms, and other cellular debris.
pustule: a small skin elevation or blister containing pus.
p-value: a probability value reported in experiments such as clinical trials. See statistical significance.
PWA: person or people with AIDS.
PWHIV (aka PWH): person or people with HIV.
pyridoxine (aka vitamin B6): See vitamin B.
pyrimidine: one of the two types of nucleotide base that make up DNA and RNA; the pyrimidine bases are cytosine, thymine, and uracil.
See also purine.
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