Published in the Bulletin of Experimental Treatments for AIDS January 1998 issue, by the San Francisco AIDS Foundation.

January 1998 Table of Contents

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Glossary

ACCELERATED APPROVAL: FDA regulations governing early marketing approval of promising drugs for life-threatening illnesses.

ACUPUNCTURE: a Chinese medical technique that involves inserting very thin needles into different acupuncture points (meridians) on the body to improve the flow of Qi (vital energy).

ACUTE RETROVIRAL SYNDROME (ARS): a combination of flu-like symptoms (e.g., fever, sore throat, skin rash, headache, nausea, muscle or joint pain) that occurs during or shortly after primary HIV infection.

ACUTE: rapid in onset; short-term initial stage of a disease.

AIDS DEMENTIA COMPLEX (ADC): mental dysfunction due to HIV infection that may be characterized by cognitive impairment, memory loss, disorientation, mood and personality changes, speech and vision difficulties, and motor dysfunction.

ALANINE TRANSAMINASE (ALT, SGPT): an enzyme produced by the liver. Abnormally high levels in the blood indicate liver disease or damage.

ALBUMIN: a protein found in bodily tissues and fluids. A low serum albumin level suggests liver damage.

ALKALINE PHOSPHATASE: an enzyme found in various body tissues and fluids. A high level suggests liver damage.

AMINO ACID: an organic compound that is a basic building block of proteins.

ANABOLIC STEROID: a hormone (e.g., testosterone, oxandrolone) that promotes the synthesis of proteins and the building of muscle mass.

ANAPHYLAXIS: a life-threatening allergic reaction to a foreign antigen.

ANERGY (adjective ANERGIC): the lack of an immune response to a foreign antigen.

ANTIBODY (AB, IMMUNOGLOBULIN, IG): a protein secreted by activated plasma cells, which evolve from B-cells, in response to stimulation by an antigen.

ANTIGEN: any agent or substance (e.g., microorganisms or the substances they produce) that stimulates an immune response.

ANTIOXIDANT: a substance that inhibits an oxidation reaction by binding with and neutralizing free radicals and other highly reactive molecules, thus reducing oxidative damage.

ANTIRETROVIRAL: an agent that suppresses the activity or replication of retroviruses such as HIV.

APHASIA: loss of ability to speak or understand language.

APHTHOUS ULCER: a shallow, often painful lesion on the mucous membranes of the mouth, esophagus or rectum.

APOPTOSIS: programmed cell death.

ASPARTATE TRANSAMINASE (AST, SGOT): an enzyme produced by the liver. Abnormally high levels in the blood indicate liver disease or damage.

ASYMPTOMATIC: not feeling or showing outward signs of infection.

AUTOLOGOUS: derived from the same individual. An autologous transfusion or transplant is one in which a person's own blood or tissues are removed and reintroduced at a later time.

BASELINE: a known value (e.g., baseline viral load) against which later measurements can be compared.

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.

BILIRUBIN: a yellowish pigment released by red blood cells when they are broken down. An excess level of serum bilirubin is characterized by jaundice (yellowing of the skin and eyes), and may indicate liver inflammation.

BIOAVAILABILITY: the extent to which a drug is absorbed and circulated in the body.

BIOPSY: the removal of a small sample of cells or tissue for microscopic examination and/or culture.

BLOOD-BRAIN BARRIER: a physical barrier between the blood vessels and the brain that allows only certain substances to pass through.

BONE MARROW: the soft, spongy tissue in the interior of certain bones that is the site of blood cell production.

BOOSTER: a subsequent dose given some time after the initial administration of a vaccine to enhance or restore its effectiveness.

BRANCHED-CHAIN DNA ASSAY (bDNA): a test for measuring the amount of virus (viral load) in blood plasma or tissue.

BREAKTHROUGH: a condition that has developed despite measures to prevent it. Also, a rise in viral load after it has fallen due to anti-HIV therapy.

BURKITT'S LYMPHOMA: a cancer of the lymphatic system associated with the Epstein-Barr virus.

CANDIDIASIS: a disease caused by the yeast-like fungus Candida. Candidiasis may affect the skin, nails and mucous membranes throughout the body including the mouth (thrush), esophagus and vagina.

Carcinogen: a chemical or physical agent (e.g., a drug, radiation) that facilitates the development of cancer.

CARCINOMA: a malignant tumor of the epithelial cells that line body surfaces and cavities.

CARRIER: a person who does not show symptoms of a disease but who carries the organism (e.g., hepatitis B) and may infect others.

CCR5: a protein found on certain blood cells that acts as a receptor site for chemokines and as a co-receptor for HIV.

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.

CD4: a protein marker on the surface of certain types of T-lymphocytes and other cells. HIV uses the CD4 receptor to enter cells.

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).

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.

CHEMOKINE: a soluble factor secreted by certain immune system cells that stimulates the activity of other cells. Certain chemokine receptors (e.g., CCR5, CXCR4) are necessary for entry by HIV into cells.

CHEMOTHERAPY: the use of chemicals or drugs to treat disease.

CHOP: a chemotherapeutic regimen for cancer treatment that combines cyclophosphamide, doxorubicin, vincristine and prednisone.

CHROMOSOME: a structure of compact, intertwined molecules of DNA found in the nucleus of cells.

CHRONIC: slow, persisting over a long period.

CIRRHOSIS: a condition in which the liver becomes scarred, fibrous and filled with fat, thus reducing its ability to function.

COAGULATION: clotting; the transformation of a liquid (e.g., blood) into a solid mass.

COHORT: a group of individuals in a study who share a demographic, clinical or other statistical characteristic (e.g., age, study site).

CO-INFECTION: concurrent infection with more than one disease-causing organism.

COMPLEMENTARY AND ALTERNATIVE MEDICINE (CAM): a type of therapy not considered standard practice in a given culture. In most Western countries, CAM includes traditional Chinese medicine, homeopathy, naturopathy and chiropractic. Complementary therapy is typically used as an adjunct to standard therapy, while alternative medicine is used instead of standard therapy.

COMPUTED TOMOGRAPHY SCAN (CT SCAN): a method of visualizing soft tissues of the body using X-rays.

CONTRAINDICATION: a circumstance or condition 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.

CROSS-RESISTANCE: the development of resistance to one agent (e.g., drug) which also confers resistance to another (often similar) agent.

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.

CXCR4 (FUSIN): a co-receptor on the surface of certain T-cells that, along with the CD4 molecule, allows HIV to infect a cell.

CYTOCHROME P450 SYSTEM: a system that metabolizes drugs and other foreign substances in the liver by means of enzymes (e.g., CYP3A4) that inhibit or promote metabolic reactions.

CYTOKINE: an intercellular chemical messenger protein (e.g., tumor necrosis factor, interleukin) released by white blood cells. Cytokines facilitate communication among immune system cells and between immune system cells and the rest of the body.

CYTOMEGALOVIRUS (CMV, HHV-5): a herpesvirus. In immunocompromised individuals CMV may cause retinitis, pneumonia, colitis and/or encephalitis.

CYTOPLASM: the gel-like substance that makes up the interior of cells.

CYTOTOXIC T-LYMPHOCYTE (CTL, T-KILLER CELL): an immune system white blood cell that targets and kills cells infected with microorganisms.

DEMENTIA: a loss of mental capacity due to an organic cause.

DISSEMINATE: to spread; a disseminated infection is one that is distributed throughout the body.

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.

EFFICACY: effectiveness.

EMPIRIC DIAGNOSIS/TREATMENT: evaluation and/or treatment based on observation and experience alone, without relying on laboratory test results.

ENCEPHALITIS: an 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.

EPSTEIN-BARR VIRUS (EBV, HHV-4): a herpesvirus. EBV infection is common in children and may cause infectious mononucleosis in young adults; it is associated with oral hairy leukoplakia, lymphoid interstitial pneumonitis and some types of cancer in people with HIV.

ESOPHAGUS (adjective ESOPHAGEAL): the swallowing tube; the portion of the digestive canal between the oral cavity and the stomach.

FECAL-ORAL ROUE: a route of transmission of infectious organisms which involves the ingestion of feces or of food or water contaminated by fecal material.

FIBROSIS: the development of fibrous tissue.

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.

FULMINANT: severe or aggressive.

GAMMA GLOBULIN (IgG): a type of antibody. Gamma globulin is used as postexposure prevention for certain diseases (e.g., hepatitis A).

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.

GENOME: the unique genetic code or hereditary material of an organism, carried by chromosomes in the nucleus of each cell.

GENOTYPE (adjective GENOTYPIC): the specific genetic makeup or "blueprint" of an organism. Genotypic resistance testing determines whether an organism's genetic structure contains certain mutations.

HAART: highly active antiretroviral therapy, a term for aggressive anti-HIV treatment usually including a protease inhibitor drug.

HBIG: antibodies used as postexposure prevention for hepatitis B.

HEPATIC: relating to the liver.

HEPATITIS: an inflammation of the liver that may be caused by several agents, including viruses and toxins. Hepatitis is characterized by fever, jaundice, swollen liver, fatigue and abnormal liver function tests. Hepatitis A virus (HAV) causes an inflammatory viral disease with a short incubation period. Hepatitis B and C virus can become chronic and may result in liver damage, cirrhosis and/or liver cancer. There are also hepatitis viruses D, E, F and G.

HEPATOCELLULAR CARCINOMA: a type of liver cancer that may result from chronic hepatitis.

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"); HSV-2 is usually sexually transmitted and generally produces lesions in the genital and/or anal area.

HERPESVIRUS: a group of viruses that includes herpes simplex virus types 1 and 2, varicella-zoster virus, Epstein-Barr virus, cytomegalovirus, human herpesvirus types 6 and 7, and Kaposi's sarcoma-associated herpesvirus.

HETEROZYGOUS: possessing 2 different alleles, or gene variants, at a given site on a chromosome.

HIVIG: concentrated anti-HIV antibodies used in passive immunotherapy.

HOMOZYGOUS: possessing 2 copies of the same allele, or gene variant, at a given site on a chromosome.

HORMONE: a chemical messenger involved in the regulation and coordination of cellular and bodily functions.

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 and anal cancer.

HUMORAL 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.

HYPERTHERMIA: abnormally high body temperature. Also refers to an experimental therapy in which blood is removed from the body, heated and returned to the circulation.

IMMUNE GLOBULIN: see antibody.

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 by exposing the person to a small amount of the organism (killed or inactivated) or pieces of the organism.

IMMUNOCOMPROMISE: reduction in immune system function.

IMMUNOTHERAPY (IMMUNE-BASED THERAPY): a therapy that attempts to modify or enhance immune response, or to reconstitute a damaged immune system.

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.

INCIDENCE: the number of new cases of a disease or condition in a specific population over a given period of time.

INCUBATION PERIOD: the time between initial infection and the appearance of symptoms

INFILTRATE: a collection of inflammatory cells, foreign organisms and cellular debris.

INFLAMMATION: the body's response to tissue injury or infection, which typically includes increased vessel dilation and permeability, resulting in redness, swelling, heat and pain.

INFUSION: the direct introduction of a substance into the bloodstream over a period of time.

INTERFERON: a cytokine (messenger protein) that plays a role in immune response. Interferon-alpha is used as a treatment for chronic hepatitis and is under study for progressive multifocal leukoencephalopathy.

INTERLEUKIN (IL): a cytokine secreted by immune cells that regulates a range of immune system functions. IL-2 is produced by activated CD4 cells and promotes the proliferation and activity of CD4 cells, CTL and natural killer cells.

INVESTIGATIONAL NEW DRUG (IND): an FDA classification applied to experimental drugs undergoing trials to assess safety and efficacy prior to marketing approval.

IVIG: intravenous immune globulin, broad-spectrum concentrated antibodies administered intravenously to treat certain infectious diseases.

JAUNDICE: a yellow discoloration of the skin and whites of the eyes caused by high blood levels of the pigment bilirubin. Jaundice is a sign of liver damage or dysfunction.

KAPOSI'S SARCOMA (KS): an abnormal or cancerous proliferation of cells of the 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 substances (e.g., drug crystals, minerals) in the kidney, which may lead to blockage and pain.

KILLER T-CELL: see cytotoxic T-lymphocyte.

LEAN BODY MASS: muscle and organ tissue.

LEUKEMIA: a cancerous disease of the blood characterized by the proliferation of leukocytes (white blood cells).

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).

LIVER ENZYME: a protein produced by the liver (e.g., ALT or AST) that catalyzes various physiological reactions. Abnormally high levels of liver enzymes in the blood may indicate liver damage or disease.

LIVER FUNCTION TEST: a blood test that measures levels of liver enzymes to indicate how well the liver is working and whether it might be inflamed or damaged.

LOG: refers to quantities in factors of 10. A log change is an exponential or 10-fold increase or decrease (e.g., going from 10 to 100 is a 1-log increase).

LONGITUDINAL: refers to a study that follows participants over an extended period of time.

LYMPH NODE: small, bean-sized organs located throughout the body. Lymph nodes filter out antigens and are the site of antigen presentation and immune activation.

LYMPHADENOPATHY: any abnormality of the lymph nodes. Usually refers to swollen and tender lymph nodes due to an infectious disease or lymphoma.

LYMPHATIC SYSTEM (adjective LYMPHOID): a network of capillary-like vessels, ducts, nodes and organs that helps maintain the fluid environment of the body and coordinates immune responses. The lymphoid organs include the lymph nodes, spleen, thymus, tonsils and adenoids.

LYMPHOCYTE: a type of white blood cell (e.g., T-cell, B-cell) responsible for immune defense.

LYMPHOMA: a malignant disease (cancer) of the lymphoid tissue. Lymphomas are classified as Hodgkins disease or non-Hodgkins lymphoma.

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.

MBACOD: a chemotherapeutic cancer treatment regimen that combines the drugs methotrexate, bleomycin, doxorubicin (Adriamycin), cyclophosphamide, vincristine (Oncovin) and dexamethasone.

METABOLISM (adjective METABOLIC): the process of building the body's molecular structures from nutrients (anabolism) and breaking them down for energy production (catabolism).

MICROBICIDE: an agent that inactivates, kills or destroys microbes.

MONOCLONAL ANTIBODIES (MAB): antibodies derived (often by genetic engineering) from a single clone of cells.

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.

MONOTHERAPY: the use of a single drug or other therapy.

MUTATION: a change in the character of a gene that is perpetuated when a cell or virus divides.

MYCOBACTERIUM AVIUM COMPLEX (MAC): a disease caused by Mycobacterium avium or Mycobacterium intracellulare, bacteria found in soil and water.

N-ACETYL-CYSTEINE (NAC): a substance which is converted within the body to cysteine, an amino acid that is a component of glutathione, a major cellular antioxidant.

NAIVE: inexperienced. The term is used to describe an individual who has never taken a certain drug (e.g., AZT-naive), or to refer to undifferentiated immune system cells.

NATURAL KILLER CELL (NK CELL): a type of lymphocyte that attacks and kills tumor cells and cells infected with microorganisms.

NECROSIS: localized premature tissue death.

NEOPLASM: a tumor or growth; tissue that develops abnormally or grows more rapidly than normal and lacks structural organization and functional coordination with normal tissue.

NEUTROPENIA: an abnormally low number or a decrease in the number of neutrophils, a type of white blood cell involved in defense against bacteria and fungi.

NON-HODGKINS LYMPHOMA (NHL): a type of cancer of the lymph nodes and spleen characterized by abnormal growth of B-cells.

NON-NUCLEOSIDE REVERSE TRANSCRIPTASE INHIBITOR (NNRTI): a drug (e.g., delavirdine, nevirapine, efavirenz) that binds to and inhibits the action of the retroviral reverse transcriptase enzyme, thus blocking viral transcription and replication.

NUCLEOSIDE ANALOG (NA): a compound (e.g., AZT, ddI, ddC, d4T, 3TC, abacavir) 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 proviral DNA chain.

ONCOLOGY: the study and treatment of cancer.

OPEN-LABEL: refers to a clinical trial in which both participants and investigators know what drug is being used.

OPPORTUNISTIC INFECTION (OI): a disease (e.g., PCP, MAC, CMV disease) caused by a microorganism that does not normally cause illness in a person with a healthy immune system, but which may cause serious disease when the immune system is suppressed.

PATHOGEN: any disease-causing agent, especially a microorganism.

PATHOGENESIS: the origin and 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.

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 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.

PHARMACOKINETICS: the action of drugs in the body, including the processes of absorption, metabolism, transformation, distribution to tissues and elimination.

PHARYNX: the throat; the upper part of the gastrointestinal tract between the oral cavity and the esophagus.

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. Phase III trials may compare the drug being tested to other therapies or to placebo.

PHENOTYPE (adjective PHENOTYPIC): visible characteristics and/or behavior that result from the interaction of an organism’s genetic "blueprint" (genotype) and the environment. Phenotypic resistance testing determines whether an organism responds to a specific drug.

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.

PLASMA: the fluid, non-cellular portion of blood.

PNEUMOCYSTIS CARINII PNEUMONIA (PCP): a life-threatening type of pneumonia caused by a protozoan.

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.

POSTEXPOSURE PREVENTION (PEP): drug therapy given immediately following exposure to an infectious organism in an attempt to prevent the infection from taking hold in the body.

PRENATAL: the period preceding birth, during which the fetus develops in the uterus.

PREVALENCE: the number of individuals with a condition in a specific population.

PRIMARY HIV INFECTION (PHI): the initial introduction of HIV into the body; the earliest stage of HIV disease.

PRODROME: a set of symptoms or signs that indicate the onset of a disease.

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.

PROGNOSIS: a forecast of the probable course and/or outcome of a disease.

PROGRESSIVE MULTIFOCAL LEUKOENCEPHALOPATHY (PML): a rapidly progressing, often fatal brain disease believed to be caused by the JC papovavirus. Symptoms may include headache, changes in mental status, speech and vision difficulties, limb weakness and seizures.

PROPHYLAXIS (adjective PROPHYLACTIC): therapy that helps to prevent a disease 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 over a period of time.

PROTEASE INHIBITOR: a drug (e.g., saquinavir, indinavir, ritonavir, nelfinavir) that blocks the action of the protease enzyme, thereby preventing HIV replication.

PROTEASE: an enzyme that cleaves proteins. HIV protease cleaves the large precursor proteins produced from viral RNA into the component parts that are then assembled into new viral particles.

PROTHROMBIN TIME: a test that measures blood coagulation ability.

PROVIRUS: a viral state in which viral DNA has been inserted into the chromosome of the host cell.

PRURITUS (adjective PRURITIC): itchiness.

QI (CHI, XI): the vital energy believed to be responsible for health and disease in traditional Chinese medicine.

RADIOLOGY: the use of radiation (e.g., x-rays) to diagnose and/or treat disease.

RANDOMIZED TRIAL: an experiment arranged so as to produce a chance distribution of subjects into different treatment groups or arms.

RECEPTOR: a specific protein-binding site on a cell's surface or interior. Viruses enter cells by fusing with receptors on a cell’s surface.

RECOMBINANT: produced by genetic engineering.

RECURRENT: returning or occurring repeatedly.

REGIMEN: a formalized schedule by which drugs are administered, including the amount of drug and the number of doses in a time period.

REMISSION: an abatement in the severity of disease symptoms; a period of time during which symptoms are reduced or eliminated.

RENAL: relating to the kidneys.

REPLICATION: duplication or reproduction.

RESERVOIR: a site where an infectious agent collects and multiplies (e.g., macrophages and lymph nodes are thought to be HIV reservoirs).

RESISTANCE: the ability of a microorganism 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 the reverse transcriptase enzyme to translate their RNA into DNA.

REVERSE TRANSCRIPTASE (RT): a viral enzyme that allows a retrovirus to translate its genetic material (in the form of RNA) into DNA, which is then integrated into the chromosomes of the host cell.

REVERSE TRANSCRIPTASE INHIBITOR (RTI): a drug that blocks retroviral replication by interfering with the reverse transcriptase enzyme. RTI include nucleoside analogs (e.g., AZT, ddI, 3TC) and non-nucleoside reverse transcriptase inhibitors (e.g., nevirapine).

RNA (RIBONUCLEIC ACID): a single-stranded nucleic acid made up of nucleotides. RNA is involved in the transcription of genetic information.

RT-PCR: see polymerase chain reaction.

SALVAGE THERAPY: emergency treatment with an experimental or non-standard drug of an illness that has not responded to standard therapy.

SENSITIVITY: the ability of an organism to be affected by a drug.

SEROCONVERSION: the development of antibodies against a microorganism; the change in a person's antibody status from negative to positive.

SERUM: the fluid, non-cellular portion of blood.

SEXUALLY TRANSMITTED DISEASE (STD): a disease (e.g., gonorrhea, syphilis, chlamydiasis) that is transmitted through sexual contact.

SIDE EFFECT: an unwanted adverse reaction to a drug treatment (e.g., rash, nausea, peripheral neuropathy, bone marrow suppression, liver or kidney failure).

SPIDER ANGIOMA: a mass of visible veins on the skin surface; may be a symptom of chronic liver damage.

SPLEEN: a lymphoid organ located in the abdominal cavity. The spleen stores and disposes of red blood cells and platelets, 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.

STEM CELL: a precursor cell from which blood cells are derived. As they mature, stem cells evolve into various types of red and white blood cells and platelets.

STEROID: a family of substances that share a similar chemical structure, including certain hormones (e.g., testosterone) and various drugs.

STRAIN: a specific genetic variant of an organism.

SUBTYPE: a distinct form of a microorganism.

SURROGATE MARKER: a marker or sign (e.g., viral load or CD4 cell count) that can serve in place of a clinical endpoint.

SYNERGY (SYNERGISM): the action of 2 or more drugs working together to produce an effect greater than the expected 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).

THRUSH: oral candidiasis, a fungal infection of the mouth.

TOXICITY (adjective TOXIC): the quality of being poisonous or harmful; often used to refer to drug side effects.

TOXIN: a harmful or poisonous agent.

TOXOPLASMOSIS: an opportunistic infection caused by the microscopic protozoan Toxoplasma gondii. A common manifestation is toxoplasmic encephalitis, characterized by brain swelling, dementia, confusion, lethargy, seizures and coma.

TRADITIONAL CHINESE MEDICINE (TCM): an Asian system of healing that focuses on achieving internal balance. Practitioners use methods such as acupuncture, heat application (moxibustion), herbal preparations, food therapy, massage and exercise (Qi Gong or Tai Chi) to restore the flow of Qi (vital energy) and the balance of Yin and Yang.

TRANSAMINASE: an enzyme (e.g., ALT, AST) produced by the liver that catalyzes the transfer of amino acids. Abnormally high levels in the blood indicate liver disease or damage.

TUBERCULOSIS (TB): an infectious disease caused by Mycobacterium tuberculosis that typically affects the lungs, but may also occur in other organs (extrapulmonary TB).

TUMOR NECROSIS FACTOR (TNF): a cytokine, produced by activated monocytes and macrophages, that can destroy tumors.

ULTRASONOGRAPHY: a method of visualizing the internal parts of the body.

UNDETECTABLE: a term used to describe a viral load that is below the level of detection (sensitivity) of the test being used.

UVEITIS: an inflammation of the membranes of the eye.

VACCINE: a preparation that contains an infectious agent or its components which is administered to stimulate an immune response that will protect a person from illness due to that agent.

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).

VASCULITIS: inflammation of the blood vessels.

VIRAL LOAD: 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 the RT-PCR or branched-chain DNA (bDNA) tests.

VIREMIA: the presence of virus in the blood or plasma.

VIRUS: a minute organism that cannot grow or reproduce outside the cells 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 virus particles.

WASTING SYNDROME: a condition characterized by atrophy of lean body mass and

involuntary weight loss of more than 10% of normal body weight.

WILD-TYPE: the normal, typical form of a virus before antiviral therapy, genetic mutation or in vitro replication takes place.

Page last updated 05 February 1998