Teach Online Glossary

Definitions are given by the full name of the term or generic name of the drug, not by the abbreviation or brand name. For example, the definition of KS will be found under Kaposi's Sarcoma. The only abbreviations commonly used within definitions are HIV, AIDS, RNA, DNA, and FDA.

Terms used that are defined elsewhere in the Glossary are in CAPITALS.

The drug chart lists alternative names for commonly prescribed medications.



< A >

Abacavir (Ziagen, ABC): a NUCLEOSIDE ANALOG or NRTI made by GlaxoSmithKline. Abacavir is one of the three component drugs in TRIZIVZIR. Life-threatening allergic reaction can occur in three to five percent of people who are starting abacavir.

Abelcet: see AMPHOTERICIN B.

Accelerated Approval: expedited FOOD AND DRUG ADMINISTRATION (FDA) approval of a new treatment based on early SURROGATE MARKER data from clinical studies. The purpose of accelerated approval is to hasten the availability of new drugs for serious or life-threatening conditions.

Acemannan (Carrisyn): the potentially active ingredient in aloe vera juice. A few IN VITRO studies have suggested that acemannan has activity against HIV and also up-regulates CELL-MEDIATED IMMUNITY.

Acetaminophen (Tylenol): a synthetic drug that reduces fever and pain. It is often found in cold and flu medications.

Acidophilus: BACTERIA found in yogurt that may help restore a supportive bacterial environment in an intestinal tract if the normal intestinal bacterial population ("flora") has been disturbed by disease or ANTIBIOTICS. Ingesting acidophilus also may be useful in preventing CANDIDIASIS (THRUSH), including in the vagina.

Acquired Immune Response: see IMMUNE SYSTEM.

Acquired Immunodeficiency Syndrome (AIDS): the late stage of the illness triggered by infection with HUMAN IMMUNODEFICIENCY VIRUS (HIV). According to the official definition published by the CENTERS FOR DISEASE CONTROL (CDC), a person receives an AIDS diagnosis when he or she has a CD4 CELL COUNT of less than 200 and/or certain OPPORTUNISTIC CONDITIONS common with advanced IMMUNE DEFICIENCY (see AIDS-DEFINING ILLNESS).


Activated CD4 Cells: CD4 CELLS that have come in contact with an ANTIGEN-PRESENTING CELL and are dividing. Compare RESTING CD4 CELLS.

Activity: the ability of a drug to control or inhibit a PATHOGEN. Activity may be determined in the laboratory and differs from EFFICACY, which is the ability of a treatment to alter the course of clinical disease.

Activity Study: a study or trial that tests the ACTIVITY of a drug.


Acupressure: a Chinese therapy that is based on ACUPUNCTURE but uses finger pressure rather than needles. Acupressure is used to relieve tension, stress and pain, perhaps due to the release of endorphins.

Acupuncture: A Chinese therapy that uses needles to press energy ("chi") points on the body's surface. It may be useful as a means to reduce pain, to aid in quitting smoking or to treat alcoholism and drug abuse.

Acute: refers to intense, short-term symptoms or illnesses that either resolve or evolve into long-lasting, CHRONIC disease manifestations.


Acyclovir (Zovirax): an ANTIVIRAL drug used in the treatment of herpes simplex virus 1 (fever blisters, cold sores), herpes simplex virus 2 (genital herpes) and herpes zoster (SHINGLES). (See HERPES VIRUS.) Acyclovir comes in the form of capsules or pills, ointment or injection. Acyclovir causes few SIDE EFFECTS, occasionally nausea, vomiting or headaches.




Adefovir Dipivoxil (Hepsera, bis-POM PMEA): a NUCLEOTIDE ANALOG made by Gilead Sciences, approved to treat HEPATITIS B infection. A program to develop a higher dose of adefovir for the treatment of HIV was halted due to NEPHROTOXICITY.

Adenine: one of the four bases of RNA (which also includes CYTOSINE, GUANINE and URACIL) and DNA (which also includes cytosine, guanine and THYMINE).

Adenopathy: an enlargement of the LYMPH NODES or other glands.

Adenosine: a NUCLEOSIDE of ADENINE. DIDANOSINE (ddI) is an ANALOG of adenosine.

Adenovirus: a group of VIRUSES that causes upper respiratory tract infections, including the common cold, as well as gastrointestinal and eye infections.

Adherence: the degree to which a patient sticks to a schedule for taking medicines. Non-adherence may lead to drug RESISTANCE. A synonym for compliance.

Adipocyte: a cell that makes up fat tissue.

Adipogenesis: a process by which STEM CELLS mature into ADIPOCYTES, or fat cells.

Adipose: fat.

Adjuvant: in VACCINES, a substance added to increase the IMMUNE RESPONSE to the ANTIGEN.

Adjuvant Therapy: a secondary therapy that is intended to improve the outcome of primary therapy. For example, after removing a cancerous tumor (primary therapy), CHEMOTHERAPY is often used as adjuvant therapy.

Administration: the way in which a drug is taken, e.g., orally or by injection.

Adrenal Glands: a pair of glands located on the kidneys. The adrenal glands secrete steroid hormones, CORTISOL and adrenaline.

Adriamycin: see DOXORUBICIN.


Adverse Event: a toxic reaction to a medical therapy. These can be mild (headache, drowsiness) to severe (kidney or liver failure, seizures, PERIPHERAL NEUROPATHY). Also see SIDE EFFECT.

Adverse Reaction: see ADVERSE EVENT.

Aerosolized: a form of a drug that has been made into a fine mist for inhalation.

Affective: relating to psychological mood.

Affective Illness: a condition that affects moods, e.g., DEPRESSION.

Agenerase: see AMPRENAVIR.

Agonist: (1) A drug or other substance that enhances the effect of another drug or substance; (2) an agent that promotes cellular activity by binding to a CELL SURFACE RECEPTOR. Compare to ANTAGONIST.


AIDS Clinical Trials Unit (ACTU): a site at which AIDS drug CLINICAL TRIALS, sponsored by the NATIONAL INSTITUTE OF ALLERGY AND INFECTIOUS DISEASES (NIAID), are performed.

Adult AIDS Clinical Trials Group (AACTG): a network of medical centers around the country in which federally funded CLINICAL TRIALS are conducted to test the safety and effectiveness of treatments for HIV infection and its complications. ACTG studies are sponsored by the NATIONAL INSTITUTE OF ALLERGY AND INFECTIOUS DISEASES (NIAID), a branch of the NATIONAL INSTITUTES OF HEALTH (NIH). See also: Pediatric AIDS Clinical Trials Group (PACTG)

AIDS-Defining Illness: one of the serious illnesses that occurs in HIV-positive individuals and a reason for an AIDS diagnosis according to the CENTERS FOR DISEASE CONTROL's definition of AIDS. Among these conditions are PNEUMOCYSTIS CARINII PNEUMONIA (PCP), MYCOBACTERIUM AVIUM COMPLEX (MAC), AIDS DEMENTIA COMPLEX, AIDS WASTING SYNDROME, invasive cervical cancer and KAPOSI'S SARCOMA (KS).

AIDS Dementia Complex (ADC): a brain disorder in people with AIDS that results in the loss of cognitive capacity, affecting the ability to function in a social or occupational setting. Its cause has not been determined exactly, but may result from HIV infection of cells in the brain or an inflammatory reaction to HIV infection.

AIDS Drug Assistance Program (ADAP): ADAPs serve people with HIV/AIDS who are uninsured or underinsured, including those who are not disabled and, therefore, ineligible for programs like Medicaid. ADAPs are authorized by the RYAN WHITE CARE ACT. Federal funding goes to states, which use a portion of the money to provide HIV/AIDS drugs, including PROPHYLAXIS and treatments of OPPORTUNISTIC CONDITIONS, to those who cannot otherwise afford the medications.

AIDS-Related Complex (ARC): an archaic term for a stage before AIDS, with symptoms such as swollen LYMPH NODES, long-lasting night sweats, fevers and unusual weight loss. Also commonly called symptomatic HIV infection. The term is no longer officially recognized by the CENTERS FOR DISEASE CONTROL.

AIDS-Related Wasting: see WASTING SYNDROME.


Alanine Aminotransaminase (ALT): a liver ENZYME, like ASPARTATE AMINOTRANSAMINASE, that plays a role in PROTEIN METABOLISM. Elevated SERUM levels of ALT are a sign of liver damage from disease or drugs. ALT is also known as serum glutamic pyruvic transaminase (SGPT).

Albendazole (Albenza): an approved treatment for two types of tapeworm larvae, which has been proposed as a treatment for MICROSPORIDIOSIS. The drug works by inhibiting cellular movement. Albendazole frequently impairs liver function and occasionally produces life-threatening reductions in total white blood cell (LEUKOCYTE) count.

Albenza: see ALBENDAZOLE.

Alfa Interferon: see ALPHA INTERFERON.

Alkaline Phosphatase: an ENZYME produced in the liver as well as in bone and other tissues. Elevated SERUM levels of the enzyme are indicative of liver disease, BILE DUCT obstruction in particular.

Allele: an alternate form of a specific GENE on a chromosome. Each allele is an individual member of a gene pair and is inherited from one parent.

Alopecia: hair loss.

Alpha Interferon (alfa-IFN, Roferon, Intron A, Pegasys, PEG-Intron): 1) a substance secreted by virally infected cells that strengthens the defenses of nearby uninfected cells. 2) alfa-IFN is an approved treatment for KAPOSI'S SARCOMA, HEPATITIS B and HEPATITIS C. Also see INTERFERON, PEGYLATED INTERFERON.


Alternative Medicine: a catch-all phrase for a long list of treatments or medicinal systems, including traditional systems such as Chinese or Ayurvedic medicine as well as homeopathy, various herbal and many other miscellaneous treatments that have not been accepted by the mainstream, or Western, medical establishment. Alternative medicine may also be referred to as COMPLEMENTARY MEDICINE. The designation alternative medicine is not equivalent to HOLISTIC MEDICINE.

Ambien: see ZOLPIDEM.

Ambulatory: the ability to walk or move about unaided. Ambulatory care usually refers to outpatient medical care, and an ambulatory patient is one who is not bedridden.

Amdoxovir: an experimental NUCLEOSIDE ANALOG from Gilead Sciences.

Amebiasis: see AMOEBIASIS.

Amenorrhea: a temporary or permanent suppression of menstruation.

Amino Acid: any of the nitrogen-containing ORGANIC MOLECULES that are the building blocks for PROTEINS. The human body uses 20 of the 80 amino acids found in nature.

Amitriptyline (Elavil): a TRICYCLIC ANTIDEPRESSANT that is also sometimes used to treat pain.

Amoebiasis: a parasitic intestinal infection caused by tiny unicellular microorganisms called amoebas. Symptoms include diarrhea, bloating and abdominal pain. Also called amebiasis.

Amphotericin B (Fungizone, Abelcet, AmBisome): an INTRAVENOUS drug for treatment of CRYPTOCOCCAL MENINGITIS, CANDIDIASIS, HISTOPLASMOSIS and coccidiomycosis and other fungal infections. TOXICITIES are severe and include fevers, chills, headache, ANOREXIA, nausea, vomiting, diarrhea, kidney damage and NEUTROPENIA. LIPID-complexed, somewhat safer, forms of IV amphotericin B (brand names: Abelcet, AmBisome) are available.

Amprenavir (Agenerase): a PROTEASE INHIBITOR made by GlaxoSmithKline. It is available in capsule form or as an oral suspension. Common ADVERSE EVENTS are nausea and vomiting. There is also a heavy PILL BURDEN. A PRODRUG of amprenavir (see VX-175/GW-433908) is in development and may require fewer and smaller capsules.

Amyl Nitrate (Poppers): an inhalant that dilates the blood vessels, producing a temporary high. It is used recreationally to enhance sexual enjoyment. Amyl nitrate should not be used with Viagra (SILDENAFIL CITRATE).

Amylase: a starch-splitting ENZYME secreted by salivary glands and the pancreas to aid digestion of food. An increase in amylase SERUM levels may indicate PANCREATITIS, a possible life-threatening consequence of DIDANOSINE (ddI).

Anabolic: refers to metabolic processes that build new tissue in the body. Compare CATABOLIC.

Anabolic Steroid: a synthetic STEROID used to increase muscle mass and weight. Anabolic steroids are versions of the natural hormone TESTOSTERONE but have fewer masculinizing, or androgenic, effects. Anabolic steroids have been used to reverse AIDS-related WASTING SYNDROME in men with low testosterone levels, although long-term safety and EFFICACY of this treatment are not known.

Anadrol: see OXYMETHOLONE.

Analgesic: both noun and adjective, refers to a compound or therapy that reduces pain. Tylenol, aspirin and the OPIATES are examples of analgesic drugs.

Analog (Analogue): a molecule that resembles another molecule structurally and that can, often, be substituted for the original. NUCLEOSIDE ANALOGS are non-functioning analogs of molecules that HIV uses to copy its DNA.

Anaphylaxis: a severe allergic reaction to an ANTIGEN, causing airway closure, low blood pressure and lung spasms. In the absence of treatment, this condition ultimately leads to life-threatening shock (collapse due to insufficient blood flow in the body) and death. Prompt treatment with an injection of epinephrine reverses the symptoms.

Ancobon: see FLUCYTOSINE.

Androgen: a HORMONE or synthetic substance with masculinizing (or androgenic) effects, such as TESTOSTERONE.

Anecdotal Evidence: evidence that has not been confirmed by controlled scientific methods, usually presented as individual case reports.

Anemia: the incapacity of blood to transport enough oxygen to the body's tissues. Anemia may be caused by an abnormally low number of red blood cells or insufficient or defective HEMOGLOBIN, the PROTEIN that carries oxygen in red blood cells. It is a condition that is often caused by AZT (ZIDOVUDINE), as well as by other drugs and illnesses that suppress red blood cell production in the BONE MARROW.

Anergic: relating to the IMMUNE SYSTEM's inability to produce a marked reaction in response to foreign ANTIGENS. For example, HIV-infected individuals who do not react to the TUBERCULOSIS skin test (see PURIFIED PROTEIN DERIVATIVE TEST) even though they have contracted a tuberculosis infection are considered to be anergic.

Angiogenesis: the process of new blood vessel growth. Tumors and KAPOSI'S SARCOMA lesions stimulate angiogenesis to supply themselves with blood.

Anorexia: a lack or loss of appetite that leads to significant decline in weight.

Antagonist: a characteristic of drugs when their combined effect is less than the sum of their individual effects. Compare AGONIST.

Antibiotic: an agent that kills or inhibits the growth of microorganisms, especially a compound similar to those produced by certain FUNGI for destroying BACTERIA. An antibiotic is used to combat infection.

Antibody: a disease-fighting PROTEIN created by the IMMUNE SYSTEM, also known as IMMUNOGLOBULIN. Antibodies coat, mark for immune destruction or render harmless foreign matter such as BACTERIA, VIRUSES or dangerous toxins. Antibodies also tag virus-infected cells, making them vulnerable to attack by the IMMUNE SYSTEM. Each antibody attaches itself to a single specific chemical sequence (EPITOPE) in an ANTIGEN.

Antibody-Dependent Cell-Mediated Cytotoxicity (ADCC): an IMMUNE RESPONSE that results when ANTIBODIES attach to ANTIGENS on the surface of a cell. The cell that is covered by the antibodies is destroyed by white blood cells (LEUKOCYTES).

Antibody-Mediated Immunity: a type of IMMUNE RESPONSE that involves the mobilization of B CELLS, which produce ANTIBODIES.

Antibody Positive: the presence of ANTIBODIES in the blood that indicates previous exposure to a particular ANTIGEN.

Antiemetic: a drug that lessens nausea and vomiting.

Antigen: a foreign substance, usually a PROTEIN that stimulates an immune response. An antigen may have several subunits called EPITOPES that are targets of specific ANTIBODIES or CYTOTOXIC T LYMPHOCYTES.

Antigen Presenting Cell (APC): a cell, such as a MACROPHAGE or DENDRITIC CELL, that digests foreign bodies and exhibits the resulting pieces of the PROTEIN (ANTIGEN) on its surface in an effort to find and activate the CD4 CELLS responsive to that antigen.

Antioxidant: a substance that prevents or reverses OXIDATION. Antioxidants are produced by the body and can be added to the diet (e.g., VITAMINS A, C and E).

Antiretroviral (ARV): a substance that stops or suppresses the activity of a RETROVIRUS, such as HIV. NUCLEOSIDE ANALOGS and PROTEASE INHIBITORS are examples of antiretroviral drugs.

Antisense Drug: a synthetic segment of DNA or RNA that locks onto a strand of DNA or RNA with a complementary sequence of NUCLEOTIDES. Antisense drugs are designed to block viral genetic instructions, marking them for destruction by cellular ENZYMES, in order to prevent the building of new VIRUS or the infection of new cells.

Antiviral: a substance that stops or suppresses the activity of a VIRUS, including a RETROVIRUS.

Antivirogram: a phenotypic resistance assay made by Virco (see PHENOTYPIC ASSAY).

Anxiolytic: a drug or substance that reduces anxiety.


Aphasia: the loss of ability to speak or understand speech.

Aphthous Ulcer: a painful sore in the mouth or esophagus of unknown cause with a deep eroded base. Aphthous ulcers are common in people with HIV and are treated with CORTICOSTEROIDS or THALIDOMIDE.

Apoptosis: cellular self-destruction that can be triggered by stimulation of particular CELL SURFACE RECEPTORS. It is a metabolic process driven by cellular ENZYMES in which the cell's CHROMOSOMES and then the cell itself breaks down into fragments. The IMMUNE SYSTEM can trigger apoptosis to eliminate unneeded cells.


Area Under the Curve (AUC): a measure of the total exposure of a drug or total effect of a treatment during a period of time. Defined by charting on a graph the changes in the critical variable over a period of time and then calculating the area between the curve and the horizontal axis (which represents elapsed time from the start of the study). Blood levels of drug and VIRAL LOAD during treatment are two parameters frequently quantified by the AUC. See also TIME-AVERAGED DIFFERENCE (DAVG).

Arm: one of the groups in a CLINICAL TRIAL.

Armamentarium: the collection of treatments available for a particular condition.

Arteriosclerosis: hardening of the arteries.

Arthralgia: joint pain.


As-Treated (AT) Analysis: a type of analysis of a CLINICAL TRIAL in which only the data from those patients who completed the study are included. Compare INTENT-TO-TREAT ANALYSIS.

Ascites: an accumulation of abdominal fluid due to low blood albumin, which is a potential complication from CIRRHOSIS.

Ascorbate: see ASCORBIC ACID.

Ascorbic Acid: an ANTIOXIDANT used to produce collagen (which is used for healing wounds) and strengthen connective tissues. It may also help immune function. Deficiency leads to scurvy. Also called ascorbate or VITAMIN C.

-ase: a suffix indicating that a substance is an ENZYME.

Aspartate Aminotransaminase: a liver ENZYME, like ALANINE AMINOTRANSAMINASE, that plays a role in PROTEIN METABOLISM. Elevated SERUM levels of AST are a sign of liver damage from disease or drugs. AST is also known as serum glutamic oxaloacetic transaminase (SGOT).

Aspergillus: a FUNGUS that infects the lungs, causing a disease known as aspergillosis. The infection can spread through the blood to other organs and cause lesions in the skin, ear, nasal sinuses and lungs, as well as occasionally in the bones, MENINGES, heart, kidneys or SPLEEN.

Assay: a test.

Association: a relationship that is more than would be expected by pure chance, but which is not necessarily causal.


Asthenia: weakness, debility.

Asymptomatic: without signs or symptoms of disease or illness.

Ataxia: lack of muscular coordination; a disorder of gait.

Atazanavir (Reyataz): an HIV PROTEASE INHIBITOR made by Bristol-Myers Squibb.

Atorvastatin (Lipitor): a LIPID-lowering drug.

Atovaquone (Mepron): an oral medication for mild to moderate cases of PNEUMOCYSTIS CARINII PNEUMONIA and, in some cases, TOXOPLASMOSIS. Atovaquone should be used with caution with RIFAMPIN, which can lower atovaquone blood levels.

Atrophy: a wasting or shrinking of cells, tissue, organs or muscle.

Attenuated Virus: a weakened VIRUS strain that can no longer infect or produce disease. An attenuated virus might potentially be used as a VACCINE.

Atypia: an abnormality in the cells of the cervix that can be discovered through a PAP SMEAR.


Autoimmune Disease: an ailment caused by an IMMUNE RESPONSE against an individual's own tissues or cells.

Autologous: referring to a naturally occurring substance derived from and used within the same individual. Compare ENDOGENOUS.

Average: the result of adding several quantities together and dividing the total by the number of quantities. For example, the average of 10, 20, and 60 is 30 (10 + 20 + 60 = 90 divided by 3 is 30). Also called the mean. Compare MEDIAN.

Azidothymidine: see ZIDOVUDINE.

Azithromycin (Zithromax): an ANTIBIOTIC approved for the prevention of MYCOBATERIUM AVIUM COMPLEX (MAC) as well as treatment of CHLAMYDIA and bacterial infections of the skin and respiratory tract. It may also have activity against TOXOPLASMOSIS and CRYPTOSPORIDIOSIS. SIDE EFFECTS include nausea, diarrhea, dizziness, sensitivity to sunlight and vaginal CANDIDIASIS.

Azole: a member of a class of antifungal drugs that includes FLUCONAZOLE and ITRACONAZOLE.


< B >


B Cell (B Lymphocyte): a type of LYMPHOCYTE that is a precursor to PLASMA cells. During infections, individual B cell clones multiply and are transformed into plasma cells, which produce large amounts of ANTIBODIES against a particular ANTIGEN on a foreign MICROBE. This transformation mainly occurs through interaction with the appropriate CD4 CELLS.

B Lymphocyte: see B CELL.

Bacteremia: the presence of BACTERIA in the blood.

Bacteria (singular: Bacterium): single-celled organisms belonging to a primitive group of living things characterized by a lack of certain cellular components found in more advanced organisms.

Bacterial Vaginosis: a bacterial infection of the vagina.


Base Pairing: during genetic replication, the process where nucleic acid bases pair with their complements (ADENINE pairs with THYMINE or URACIL and CYTOSINE pairs with GUANINE).

Baseline: the initial time point in a CLINICAL TRIAL or treatment REGIMEN, just before someone starts to receive the treatment in question. At this reference point, measurable values such as CD4 CELL COUNT and VIRAL LOAD are recorded so they can be compared to later results. Safety and EFFICACY of a drug are often determined by monitoring changes from the baseline values.


Benzodiazepine: a class of psychoactive drugs used to treat anxiety, insomnia or pain. Examples include alprazolam (Xanax), diazepam (Valium) and clonazepam (Klonopin).

Beta Carotene: a compound that is converted to VITAMIN A in the body. Beta carotene is a red-orange pigment found in dark green and yellow fruits and vegetables. It is a nontoxic source of vitamin A.

Beta-2 Microglobulin: a PROTEIN of the IMMUNE SYSTEM found in the blood. Elevated blood levels of this protein are associated with immune activation and are weakly predictive of worsening of HIV infection.



Bicyclam: a class of compounds that affect HIV's ability to bind to healthy cells. (See FUSION INHIBITOR.)

BID: abbreviation for bis in die, a Latin phrase meaning twice a day. A drug prescribed this way should be taken every twelve hours.

Bile: a fluid secreted from the liver into the small intestine.

Bile Duct: a tract connecting the liver and small intestine through which BILE flows.

Bilirubin: a red pigment occurring in liver BILE, blood and urine. Bilirubin is the product of the breakdown of HEMOGLOBIN in red blood cells. It is removed from the blood and processed by the liver, which secretes it into the digestive tract via the bile. An elevated level in blood SERUM can be an indication of liver disease, drug-induced liver impairment or hemolysis (breakdown of red blood cells). An increase in the unconjugated form of bilirubin is a side effect of the HIV PROTEASE INHIBITOR, ATAZANAVIR, and is considered non-toxic.

Binding Site: an area where two protein molecules join together. For example, CYTOKINES bind to CELL SURFACE RECEPTORS and the GP120 PROTEIN of HIV binds to the CD4 CELL SURFACE RECEPTOR.

Bioavailability: the extent to which an oral medication is absorbed in the digestive tract and reaches the bloodstream.

Bioelectrical Impedance Analysis (BIA): a technique for indirectly measuring body fat, BODY CELL MASS, extracellular mass and extracellular fluid. Not as accurate as other measurements, it has been used to monitor changes in body composition in people with HIV.

Biopsy: the removal of a small piece of tissue either surgically or with a small aspiration needle so it can be microscopically examined to determine the type or extent of a particular disease.

Bitter Melon (MAP-30): the fruit of a Chinese vine related to the cucumber. MAP-30, which has shown some anti-HIV activity in the test tube, can be extracted from bitter melon. Little information about EFFICACY or proper use is available.

Bleomycin: a drug used to treat cancer that interferes with the reproduction of cancerous cells. Bleomycin is used as a treatment for KAPOSI'S SARCOMA (KS).

Blinded: a term used to describe a CONTROLLED TRIAL where the participants do not know which ARM of the trial they are in and precisely which study treatment they are receiving. If researchers do not know either, the trial is DOUBLE-BLINDED.

Blood-Brain Barrier: the protective barrier that restricts the passage of many substances from the blood to the tissues of the brain. Not all drugs can cross this barrier.

Blood-Brain Penetration: the ability of a drug or other substance to cross the BLOOD-BRAIN BARRIER.

Blood Plasma: see PLASMA.

Blood-Retina Barrier: the barrier that prevents the passage of most substances from the blood to the RETINA, making it difficult to treat eye disease with systematically administered medicines, e.g., pills and intravenous infusions.

Blood Sugar: GLUCOSE in the blood.

Bloodwork: various laboratory tests that analyze characteristics of the blood.



Bodily Fluids: refers to liquids naturally produced by the body such as urine, saliva and tears. The only bodily fluids having a high risk for transmission of HIV are blood, semen, vaginal secretions and breast milk.

Body Cell Mass: consists of cells in the muscles and organs, as well as circulating cells. The body cell mass consumes oxygen and produces carbon dioxide, and it is the compartment where all metabolic activity occurs.

Body Composition: what makes up the body, e.g., fat, LEAN BODY MASS, water. Abnormal changes in body composition with fat redistribution, generally referred to as LIPODYSTROPHY, have been noted in people on ANTIRETROVIRAL medications. See also WASTING SYNDROME.

Body Mass Index (BMI): an index used to relate a person's weight and height. The BMI is a person's weight in kilograms divided by height in meters squared. It correlates strongly with total body fat content in adults.

Bone Marrow: soft tissue located in the cavities of bones. It is the site of blood cell production.

Bone Marrow Suppression: a SIDE EFFECT of many anticancer and ANTIVIRAL drugs, including AZT (ZIDOVUDINE). Bone marrow suppression may lead to a decrease in red blood cells (ANEMIA), white blood cells (LEUKOPENIA) or PLATELETS (THROMBOCYTOPENIA). Such reductions, respectively, result in fatigue and weakness, susceptibility to infections and spontaneous or excess bleeding.

Branched DNA (bDNA) Assay: a test developed by the Chiron Corporation for measuring the amount of HIV (as well as other VIRUSES) in blood PLASMA. The result of this test is also known as the VIRAL LOAD. The test uses a signal amplification technique, which creates a luminescent signal whose brightness depends on the amount of viral RNA present. Test results are calibrated in numbers of virus particle equivalents per milliliter of plasma (copies/ml). The bDNA test returns a result about half that of the POLYMERASE CHAIN REACTION (PCR) TEST, which uses a different technique.

Bronchitis: a disease marked by INFLAMMATION of the bronchial tubes in the lungs.

Bronchodilator: an inhalant that can reduce coughing, wheezing and shortness of breath.

Bronchoscopy: a diagnostic examination in which a fiber optic tube is inserted in the throat to enable a doctor to see the trachea and the lungs. Bronchoscopy is often used to detect PNEUMOCYSTIS CARINII PNEUMONIA (PCP).

Bronchospasm: a contraction of the muscle of the bronchi, often seen in asthma.

Buffalo Hump: see DORSAL FAT PAD

Buffered: refers to pills that include an antacid to neutralizing stomach acid, which may help reduce stomach upset or increase BIOAVAILABILITY of a drug.

Bupropion (Wellbutrin): an antidepressant that is a weak blocker of serotonin and norepinephrine. A lower dose formulation (Zyban) is used for cigarette smoking cessation. RITONAVIR may increase blood levels of bupropion, requiring a lower dose of the latter.

Burkitt's Lymphoma: a cancerous tumor, frequently involving jaw bones, ovaries and abdominal LYMPH NODES. The disease is common in Africa and has been associated with EPSTEIN-BARR VIRUS.

Buyers' Club: a nonprofit group formed to import AIDS-related therapies that are available in other countries but are not yet approved by the FDA for use in the United States. These products may be sold abroad for purposes that are not related to AIDS or HIV infection, and their use in HIV/AIDS remains speculative.

< C >

Cachexia: a general weight loss and wasting occurring in the course of a CHRONIC disease.


Calanolide A: a compound derived from a latex tree that works as a NON-NUCLEOSIDE REVERSE TRANSCRIPTASE INHIBITOR (NNRTI) and shows some anti-HIV activity. Manufactured by Sarawak MediChem Pharmaceuticals, it is currently in PHASE II CLINICAL TRIALS.

Canarypox Virus: a VIRUS that does not cause disease in humans and that is used in VACCINE research, including HIV vaccine research.

Cancer: any MALIGNANT growth.

Candida: a group of yeast-like FUNGI, in particular Candida albicans, that infect the mouth as well as other MUCOUS MEMBRANES in the esophagus, intestines, vagina, throat, skin and lungs. Oral or recurrent vaginal candida infection is an early sign of IMMUNE SYSTEM deterioration, diabetes or steroid use.

Candidiasis: an infection due to CANDIDA yeast. The symptoms of oral candidiasis (THRUSH) and vaginal candidiasis (formerly called monilia) include pain, itching, redness and white patches in their respective sites. Some common treatments are CLOTRIMAZOLE, NYSTATIN and miconazole.

Canker Sore: see APHTHOUS ULCER.

Cannabinoids: components of cannabis, including TETRAHYDROCANNABINOL (THC) (see CANNABIS).

Cannabis: a plant that contains TETRAHYDROCANNABINOL (THC), an active ingredient in marijuana. Medical uses of cannabis, or THC, include stimulation of appetite and reduction of nausea.

Capravirine (AG 1549): an experimental NON-NUCLEOSIDE REVERSE TRANSCRIPTASE INHIBITOR from Agouron.

Capsid: a part of some VIRUSES that surrounds their GENOME protecting it from the environment.

Carbohydrate: an ORGANIC MOLECULE made up solely of carbon, hydrogen and oxygen. Carbohydrates may be made up of only one or two components (mono- or di-saccharides, also called "sugars") or be complex chains of individual units (polysaccharides or "starches").

Carcinogen: a substance or agent that can cause the growth of cancer.

Carotenoids: a class of carotenes, such as BETA CAROTENE.

Carrisyn: see ACEMANNAN.

Case-Controlled Study: a RETROSPECTIVE STUDY that starts with the identification of people who have a disease or condition (the cases) and those who do not (the controls). Researchers then look for similarities and differences between the cases and controls regarding the factor or factors under investigation.


Catabolic: refers to metabolic processes that break down tissue in the body.

Catalase: a naturally occurring ANTIOXIDANT enzyme.

Category A (FDA): a drug for which adequate and well-controlled studies of pregnant women fail to demonstrate a risk to the fetus during pregnancy.

Category B (FDA): a drug for which animal reproduction studies fail to demonstrate a risk to the fetus although adequate and well-controlled studies have not been conducted.

Category C (FDA): a drug for which safety in human pregnancy has not been determined and animal studies are either positive for fetal risk or have not been conducted. Pregnant women should not use category C drugs unless the potential benefits outweigh the potential risk to the fetus.

Category D (FDA): a drug for which there is positive evidence of human fetal risk based on adverse reaction data from investigational or marketing experiences. In certain cases, the potential benefits from the use of this drug in pregnant women may be acceptable despite its potential risks.

Category X (FDA): a drug for which studies in animals or reports of adverse reactions in humans have indicated that the risk associated with its use clearly outweighs any possible benefit for a pregnant woman.

Catheter: a semi-permanent plastic or synthetic tube, usually implanted in the chest or arm for a long term, used for metered administration of a drug into the veins. See also HICKMAN CATHETER and PERIPHERALLY INSERTED CENTRAL CATHETER (PICC) LINE.


CCR5: a seven-looped PROTEIN structure that normally occurs on the surface of certain IMMUNE SYSTEM cells and acts as a CHEMOKINE receptor site. After HIV binds to the cellular receptor CD4, the R5-using strain must then bind to CCR5 before the virus can enter the cell. People who lack CCR5 receptors seem to be very resistant to HIV infection and, if infected, have a slow progression to AIDS. Compare CXCR4.

CD4: one of the PROTEIN structures on the surface of a human cell that allows HIV to attach, enter, and thus infect the cell. CD4 molecules are present on CD4 CELLS (helper T lymphocytes), MACROPHAGES and DENDRITIC CELLS, among others. Normally, CD4 acts as an accessory molecule, forming part of larger structures (such as the T CELL RECEPTOR) through which T cells and other cells signal each other. In particular, it participates in the interaction between CD4 cells and the MAJOR HISTOCOMPATABILITY COMPLEX class II molecules on ANTIGEN PRESENTING CELLS.

CD4 Cell: a type of T lymphocyte involved in protecting against viral, fungal and protozoal infections. The CD4 cell modulates the IMMUNE RESPONSE to an infection through a complex series of interactions with ANTIGEN PRESENTING CELLS (MACROPHAGES, DENDRITIC CELLS and B CELLS) and those LYMPHOCYTES that directly attack foreign ANTIGENS (B cells, again, and CD8 CELLS). CD4 cells are the primary target of HIV, and it is mainly the destruction of CD4 cells that leads to the progression of HIV disease. CD4 cells are also called helper T cells.

CD4 Cell Count: the most commonly used SURROGATE MARKER for assessing the state of the IMMUNE SYSTEM. Also called T4 cell count. As CD4 cell count declines, the risk of developing OPPORTUNISTIC CONDITIONS increases. Normal CD4 cell counts are greater than 800 per cubic millimeter of blood. According to the CENTERS FOR DISEASE CONTROL, a CD4 cell count below 200 is an AIDS-defining condition.

CD4 Percent: the percentage of total LYMPHOCYTES made up by CD4 CELLS. A common measure of immune status, CD4 percent is about 40 percent in healthy individuals and can be below 20 percent in persons with AIDS.

CD4 Receptor: see CD4.

CD4/CD8 Ratio: the ratio of CD4 CELLS to CD8 CELLS. A common measure of IMMUNE SYSTEM status, the ratio is around 1.5 to 2.0 CD4 cells to 1.0 CD8 cell in healthy individuals and falls as CD4 CELL COUNTS fall in persons with HIV infection.

CD8 Cell: a type of T CELL that bears the RECEPTOR for CD8 on its surface. The CD8 receptor helps cells interact with the ANTIGEN-presenting MAJOR HISTOCOMPATABILITY COMPLEX class I molecules on other cells. Some CD8 cells -which are called CYTOTOXIC T LYMPHOCYTES - recognize and kill cancerous cells and those infected by intracellular PATHOGENS (some BACTERIA, VIRUSES and MYCOPLASMA). Other CD8 cells are known as suppressor cells.


Cell Antiviral Factor (CAF): a so-far unidentified soluble substance that is secreted by activated CD8 CELLS and that inhibits HIV replication within cells. CAF activity seems to be high in LONG-TERM NONPROGRESSORS but low in patients who have rapid disease progression.

Cell Lines: specific cell types bred in the laboratory for use in scientific experimentation.

Cell-Mediated Immunity (CMI): one type of IMMUNE SYSTEM response, coordinated by Th1 cells, in which disease is controlled by specific defense cells (CYTOTOXIC T LYMPHOCYTES) that kill infected cells. See TH1 RESPONSE.

Cell Surface Receptor: a molecule on a cell's surface that binds with various substances, causing changes in the activity of the cell. See also RECEPTOR.

Centers for Disease Control and Prevention (CDC): the federal public health agency serving as the center for preventing, tracking, controlling and investigating the EPIDEMIOLOGY of AIDS and other diseases.

Central Nervous System (CNS): the brain, spinal cord and the protective membranes (MENINGES) surrounding them.

Cerebrospinal Fluid (CSF): fluid that bathes the brain and the spinal cord. A sample of this fluid is often removed from the body for diagnostic purposes by a LUMBAR PUNCTURE (spinal tap).

Cervical Dysplasia: changes in the lining cells of the CERVIX that may progress to cancer if not treated in time. It is caused by HUMAN PAPILLOMAVIRUS (HPV). Cervical dysplasia is detected through a PAP SMEAR.

Cervical Intraepithelial Neoplasia: see CERVICAL DYSPLASIA.

Cervicovaginal Lavage (CVL): a technique in which a saline solution is sprayed into the vaginal vault and recovered for testing. CVL can be used to determine HIV VIRAL LOAD in genital tract secretions.

Cervix: the lower, cylindrical terminus of the uterus that juts into the vagina and contains a narrow canal connecting the upper and lower parts of a woman's reproductive tract.

Chancroid: a highly contagious sexually transmitted disease caused by the Hemophilus ducreyi BACTERIUM. It appears as a pimple, chancre, sore or ulcer on the skin of the genitals. The lesion arises after an incubation period of three to five days and may facilitate the transmission of HIV. Usually treated with ERYTHROMYCIN or ceftriaxone.

Chart Review: a retrospective way of collecting data that involves examining patients' medical records.

Chemokine: a soluble chemical messenger that attracts white blood cells to a site of infection. There are two structural categories of chemokines: alpha (CXC) and beta (CC). Examples of chemokines that interfere with HIV activity are the beta chemokines MACROPHAGE INFLAMMATORY PROTEIN-1a, MACROPHAGE INFLAMMATORY PROTEIN-1b, and RANTES (REGULATED-UPON-ACTIVATION, NORMAL T-EXPRESSED AND SECRETED) and the alpha chemokine STROMAL CELL-DERIVED FACTOR-1.

Chemotaxis: the migration of cells along a chemokine gradient toward its source; a response to the chemical stimulus of a chemoattractant.

Chemotherapy: the use of chemical agents (drugs) in the treatment of a disease. The term commonly, but not always, refers to cancer treatment.

Chlamydia (Chlamydia trachomatis): the most common sexually transmitted BACTERIUM infecting the reproductive system. The infection is frequently ASYMPTOMATIC, but, if left untreated, it can cause sterility in women.

Cholestasis: obstruction of BILE within the BILE DUCT.

Cholesterol: a STEROID found in the tissues and blood PLASMA. Cholesterol circulates in the blood along with a PROTEIN (LIPOPROTEIN). LOW-DENSITY LIPOPROTEINS (LDLs) take cholesterol from the liver to body tissues while HIGH-DENSITY LIPOPROTEINS (HDLs) take cholesterol from the blood to be excreted. High levels of LDLs and/or low levels of HDLs are associated with heart disease and ARTERIOSCLEROSIS.

Chromosome: the thread-like structures in the nucleus (center) of a cell that carry genetic information. Each chromosome contains a double strand of twisted DNA. Along each strand of DNA lie the GENES.

Chronic: refers to symptoms and diseases that last for an extended period of time without noticeable change.

Cidofovir (Vistide): a NUCLEOTIDE ANALOG. Cidofovir is approved as systemic treatment for new or relapsing CYTOMEGALOVIRUS (CMV) RETINITIS. Its primary advantage over GANCICLOVIR and FOSCARNET is that cidofovir is administered intravenously on a weekly or a biweekly basis instead of daily, eliminating the need for an in-dwelling CATHETER. The chief SIDE EFFECT of intravenous administration is kidney damage, which can be very severe. To protect the kidneys, cidofovir must be administered with PROBENECID and INTRAVENOUS hydration. Cidofovir should not be used at the same time as other drugs that are toxic to the kidneys or in patients with impaired kidney function. Cidofovir is being tested for activity against KAPOSI'S SARCOMA (KS) and PROGRESSIVE MULTIFOCAL LEUKOENCEPHALOPATHY (PML).

Cimetidine (Tagamet): an antiulcer drug that blocks histamine, a substance secreted by MAST CELLS that causes the symptoms of allergy. Cimetidine has been proposed as an IMMUNE-BASED THERAPY for HIV infection.


Ciprofloxacin (Cipro): an oral ANTIBIOTIC approved for the treatment of many common bacterial and urinary infections. It is sometimes administered to treat MYCOBACTERIUM AVIUM COMPLEX (MAC) in combination with other drugs. Possible SIDE EFFECTS include gastrointestinal upset, seizures and rash.

Cirrhosis: a liver disease that results in FIBROSIS and nodule formation. It can also cause gastrointestinal problems, JAUNDICE and EDEMA. Although irreversible and a common cause of death, cirrhosis can be controlled with VITAMINS, diuretics and beta blockers. Cirrhosis can be caused by alcoholism, HEPATITIS and an obstruction in BILE flow.

Clade: one of the major, largely geographically isolated, HIV subtypes. Classification is based on differences in ENVELOPE PROTEIN. Clade B makes up the overwhelming majority of HIV in North America and Europe.

Clarithromycin (Biaxin): an ANTIBIOTIC approved for the prevention and treatment of MYCOBACTERIUM AVIUM COMPLEX (MAC) and also used for preventing this disease in people with AIDS. SIDE EFFECTS include diarrhea, nausea and abnormal taste. Clarithromycin may cause severe abdominal pain at high doses.

Clearance: the removal of something, often from the blood (e.g., through the kidneys).

Cleocin: see CLINDAMYCIN.

Clindamycin (Cleocin): an approved ANTIBIOTIC that may be an alternative treatment for PNEUMOCYSTIS CARINII PNEUMONIA (PCP) and (usually with PYRIMETHAMINE) TOXOPLASMOSIS. The most common SIDE EFFECT is diarrhea, which is caused by an overgrowth of an intestinal BACTERIUM called Clostridium difficile during clindamycin therapy.

Clinical: refers to physical signs and symptoms directly observable in the human body.

Clinical Endpoint: a predefined outcome (e.g., clinical improvement) in a CLINICAL TRIAL that signals a study result for a particular patient.

Clinical Trial: a study done to test an EXPERIMENTAL DRUG or procedure in human beings to see whether it is safe and effective, as well as to determine its proper dose.

Clotrimazole (Lotrimin, Mycelex): an approved antifungal drug used as a TOPICAL agent for oral and vaginal CANDIDIASIS.

Cmax: the maximum concentration of a drug in the body after dosing. Cmax is often associated with SIDE EFFECTS. See also PEAK LEVEL.


Cmin: the lowest concentration of a drug after dosing. See also TROUGH LEVEL.



Coat: see ENVELOPE.

Codon: a three-NUCLEOTIDE genetic subunit that determines which AMINO ACID is placed in sequence in a PROTEIN chain. Mutations at specific HIV codons are associated with changes in the amino acid sequence of HIV's proteins and ENZYMES. Such MUTATIONS help HIV evade the effects of ANTIVIRAL drugs or specific IMMUNE RESPONSES.

Coenzyme Q10 (CoQ10): a substance that assists in the OXIDATION of nutrients within cells to create energy. It is also highly efficient at protecting internal and external cell membranes against oxidation and is sometimes proposed as a COMPLEMENTARY MEDICINE to combat AIDS-related conditions.

Cofactor: any agent or characteristic that enhances or activates disease progression.

Coformulation: the packaging of more than one drug into a single pill.

Cohort: a group of individuals with some characteristics in common that is the subject of a study of the EPIDEMIOLOGY or natural course of a disease.

Colitis: INFLAMMATION of the colon, a condition that causes abdominal pain and diarrhea.


Colposcopy: a procedure in which the surface of the uterine CERVIX is examined through a low-powered microscope for signs of CERVICAL DYSPLASIA or cancer. Colposcopy is a more accurate alternative to PAP SMEARS, but requires considerably more skill to perform.

Combination Therapy: using at least two drugs simultaneously to more effectively combat a disease. See HIGHLY ACTIVE ANTIRETROVIRAL THERAPY (HAART).

Combivir: The GlaxoSmithKline trade name for a pill that contains both ZIDOVUDINE (AZT) and LAMIVUDINE (3TC).

Community Programs for Clinical Research on AIDS (CPCRA): a branch of the NATIONAL INSTITUTES OF HEALTH'S Division of AIDS that supports CLINICAL TRIALS based on local networks of practicing physicians. These physicians collect data on their patients who are participating in a treatment trial.

Comorbidity: the coexistence of two or more diseases or conditions.

Compassionate Use: a process for providing EXPERIMENTAL DRUGS on an individual basis to very sick patients who have no treatment options, despite the fact that there is no sufficient data on the drug's effectiveness. Often, case-by-case approval must be obtained from the FDA for compassionate use of a drug. See also EXPANDED ACCESS PROGRAM, PARALLEL TRACK and TREATMENT INVESTIGATIONAL NEW DRUG.


Complementary Medicine: health care provided in addition to, or instead of, standard medical practice. See also ALTERNATIVE MEDICINE.

Complete Blood Count (CBC): a screening of the most important cellular components of the blood. A CBC includes the total white blood (LEUKOCYTE) count, counts of specific types of white blood cells, red blood cell count, HEMOGLOBIN level and PLATELET count.

Compliance: see ADHERENCE.

Compound Q (GLQ223): an extract of a Chinese wild cucumber. It is used in China to induce abortions and treat respiratory viruses. In this country, compound Q has been tested and used in the community as an anti-HIV treatment, but is now largely out of favor. Possible SIDE EFFECTS of this INTRAVENOUS medication include anaphylactic reactions (see ANAPHYLAXIS) and seizures.

Computed Tomography Scan (CT Scan): a form of x-ray examination that utilizes a special beam to produce a detailed series of images of body sections. A CT scan is also referred to as a CAT (computed axial tomography) scan.

Consensus interferon (CIFN): a novel, recombinant type 1 intereron containing 166 amino acids. CIFN was derived by scanning the sequences of several natural alpha interferons and assigning the most frequently observed amino acid in each corresponding position. CIFN, when compared on an equal mass basis with interferon (IFN) alfa-2a and alfa-2b in in vitro assays, typically displays 5-10 times higher biological activity.

Condyloma Acuminatum: a projecting warty growth on the external genitals or the anus caused by infection with the HUMAN PAPILLOMAVIRUS (HPV). It is usually a benign or non-cancerous growth. Condyloma acuminatum is also referred to as genital warts or verruca acuminata.


Confounding Factor: a variable that differs between the treatment and control groups in a study that could affect the results.

Conjunctivitis: an INFLAMMATION of the conjunctiva, which constitutes the thin protective membrane on the inner surface of the eyelids.

Contraindication: a condition or circumstance that prevents prescribing a certain treatment to an individual patient.

Control Arm: the group of participants in a CLINICAL TRIAL that receives a standard treatment and/or a PLACEBO. Those receiving the experimental treatment are compared to the control arm.

Controlled Trial: a clinical study in which one group of participants receives an EXPERIMENTAL DRUG while another group receives either a PLACEBO or an approved standard therapy. When participants do not know which group they are in, the trial is BLINDED. When the researchers are kept from knowing, too, then the trial is DOUBLE-BLINDED.

CoQ10: see COENZYME Q10.

Correlation: the statistical strength of association between two variables.

Cortex: the outer portion of an organ.

Corticosteroid: any STEROID HORMONE obtained from the CORTEX or outer portion of the ADRENAL GLAND or any synthetic substitute for such a steroid. Corticosteroids are immunosuppressive and include prednisone, corticosterone, cortisone and aldosterone.

Cortisol: a naturally occurring STEROID, secreted by the ADRENAL GLAND that affects the METABOLISM of GLUCOSE, PROTEINS and fat.


Creatinine: the product of the breakdown of creatine, an important molecule involved in energy transfer within muscle cells. The level of creatinine in the blood and urine provides a measure of kidney function.

Crix Belly: the accumulation of fat in the lower abdomen. So-called because it was first noted in association with Crixivan (INDINAVIR), although other ANTIRETROVIRALS or HIV disease itself could also be involved. See LIPODYSTROPHY.

Crixivan: see INDINAVIR.

Cross-Resistance: the phenomenon in which a MICROBE that has acquired RESISTANCE to one drug to which it has not been exposed through direct exposure to one or more other drugs. Cross-resistance arises because the site of activity of several drugs is the same, resulting in identical genetic resistance MUTATIONS.

Cross-Sectional Study: a study that examines and analyses predefined variables at a fixed time or over a short period, as opposed to a LONGITUDINAL STUDY that observes patients over time.

Cryotherapy: the use of liquid nitrogen to freeze and destroy a lesion or growth, sometimes used to induce scar formation and healing to prevent further spread of a condition (for example, warts or MOLLUSCUM CONTAGIOSUM).

Cryptococcal Meningitis: an OPPORTUNISTIC CONDITION caused by the FUNGUS Cryptococcus neoformans and involving the membranes surrounding the brain and spinal cord. Symptoms may include severe headache, confusion, sensitivity to light, blurred vision, fever and speech difficulties. Left untreated, the disease can lead to coma and death. Standard treatments are AMPHOTERICIN B (as INDUCTION THERAPY) and FLUCONAZOLE (as MAINTENANCE THERAPY).

Cryptococcus: a FUNGUS that is usually harmless, but can cause MENINGITIS in people with AIDS. It is found in pigeon droppings.

Cryptosporidiosis: an OPPORTUNISTIC CONDITION caused by the intestinal parasite Cryptosporidium parvum, a very common parasite in animals. Transmission occurs through ingestion of food or water contaminated with animal feces (this can include tap water, some bottled waters and water from lakes and ponds). The parasite grows in the intestines and BILE DUCTS and causes severe, CHRONIC diarrhea, especially in people with AIDS. There are no standard treatments, but HIGHLY ACTIVE ANTIRETROVIRAL THERAPY (HAART) and PAROMOMYCIN can be effective.




Culture: the process of growing BACTERIA or other cells in a special laboratory medium.

Curcumin: an ingredient of the spice turmeric. Laboratory studies have suggested that curcumin inhibits HIV replication by blocking the LONG TERMINAL REPEAT region on HIV's GENES, but a 1996 CLINICAL TRIAL found no ANTIVIRAL effect.

Cutaneous: relating to the skin.


CXCR4: a seven-looped PROTEIN structure that normally occurs on the surface of certain IMMUNE SYSTEM cells and acts as a CHEMOKINE receptor site. After HIV binds to the cellular receptor CD4, the X4-using strain must then bind to CXCR4 before the virus can enter the cell. Compare CCR5.

Cyclobut G: see LOBUCAVIR.


Cysteine: an AMINO ACID.

Cytidine: a NUCLEOSIDE of CYTOSINE. LAMIVUDINE (3TC) and DIDEOXYCYTIDINE (ddC) are analogs of cytidine.

Cytochrome P450 (CYP): a family of ENZYMES in the liver that metabolizes drugs and other fat-soluble substances. Certain medications, e.g., RITONAVIR, inhibit some of the P450 enzymes, in particular P450 3A4 (also called CYP3A4), affecting the liver's ability to break down other drugs. Inhibiting this enzyme will increase blood levels of medications that it normally metabolizes and dose adjustments may be necessary in order to prevent SIDE EFFECTS or overdosing. Conversely, NEVIRAPINE and EFAVIRENZ are examples of drugs that stimulate CYP3A4 causing reduced blood levels of drugs metabolized by the enzyme.

Cytokine: one of the PROTEINS produced by white blood cells (LEUKOCYTES) that act as chemical messengers between cells. Cytokines can stimulate or inhibit the growth and activity of various immune cells. Examples of cytokines are the various INTERLEUKINS and TUMOR NECROSIS FACTOR ALPHA.

Cytomegalovirus (CMV): a HERPES VIRUS infection that causes serious illness in people with AIDS. CMV can develop in any part of the body but most often appears in the RETINA of the eye, the nervous system, the colon or the esophagus.

Cytomegalovirus (CMV) Polyradiculopathy: CMV infection of the spinal roots (the bundles of nerves coming out of the spinal cord), leading to generalized weakness and paralysis.

Cytomegalovirus (CMV) Retinitis: CMV infection of the RETINA. The lesions it causes lead to deterioration in vision and ultimately blindness if untreated.

Cytosine: one of the four bases that makes up RNA (which also includes ADENINE, GUANINE and URACIL) and DNA (which also includes adenine, guanine and THYMINE). See also CYTIDINE.

Cytostatic: able to stop the growth of cells.

Cytotoxic: able to kill cells.

Cytotoxic T Lymphocyte (CTL): a type of CD8 or, less often, CD4 lymphocyte that kills diseased cells infected by a specific VIRUS or other intracellular MICROBE. CTLs interact with ANTIGEN bearing MAJOR HISTOCOMPATIBILITY COMPLEX (MHC) class I molecules on infected cells and have the prime role in CELL-MEDIATED IMMUNITY.

Cytovene: see GANCICLOVIR.

< D >



Dapsone: an antileprosy drug used in the treatment and prophylaxis of PNEUMOCYSTIS CARINII PNEUMONIA (PCP) and other diseases. Possible SIDE EFFECTS include skin rash, fever, gastrointestinal upset and destruction of red blood cells. Patients should avoid taking dapsone with buffered DIDANOSINE (ddI) or take it two hours before taking buffered ddI since the buffer reduces intestinal absorption of dapsone.

Daraprim: see PYRIMETHAMINE.

Data and Safety Monitoring Board (DSMB): an independent panel of clinical research experts responsible for the ongoing review and, when necessary, modification or termination of a CLINICAL TRIAL to insure the safety of participants.

Daunorubicin: a drug used to treat leukemia and a BONE MARROW suppressant. See also DAUNOXOME.

DaunoXome: a CYTOTOXIC CHEMOTHERAPY approved for FIRST-LINE TREATMENT for advanced KAPOSI'S SARCOMA. It consists of a preparation of DAUNORUBICIN encapsulated in LIPOSOMES, which increases the drug's stability while moderating its TOXICITIES. DaunoXome's main SIDE EFFECT is NEUTROPENIA, which can be managed with GRANULOCYTE COLONY STIMULATING FACTOR (G-CSF, Neupogen).




"d" drug: any of the NUCLEOSIDE ANALOGS ddI, d4T or ddC.


Dehydroepiandrosterone (DHEA): a HORMONE produced by the ADRENAL GLAND. Levels of DHEA are often low in people with HIV. Its biological role in the body is unclear. Some of it is converted into TESTOSTERONE and other androgenic STEROIDS. There have been anecdotal reports of the benefits of DHEA for a variety of conditions, but there is little hard evidence to support these claims. DHEA is readily available through BUYERS' CLUBS and health food stores.

Delavirdine (Rescriptor): a NON-NUCLEOSIDE REVERSE TRANSCRIPTASE INHIBITOR (NNRTI) from Agouron/Pfizer. SIDE EFFECTS include temporary skin rash in 20 percent of patients and, less frequently, nausea, headache, fatigue and diarrhea.

Delayed-Type Hypersensitivity (DTH): a cell-mediated immune reaction (see CELL-MEDIATED IMMUNITY) to certain foreign ANTIGENS applied on the surface or just under the skin. The reaction, consisting of a red bump or induration (hardening), takes 24 to 48 hours to develop. DTH, which is the process involved in the reaction to poison ivy and poison oak as well as to the TUBERCULOSIS skin test, is often used in tests of IMMUNE SYSTEM competence.


Demographics: the statistical characteristics (e.g., age, income, vital statistics) of human populations.

Dendritic Cells: immune cells with long, tentacle-like branches called dendrites. Among the dendritic cells are the LANGERHANS CELLS of the skin and FOLLICULAR DENDRITIC CELLS in the LYMPH NODES. Most dendritic cells (other than follicular dendritic cells) function as ANTIGEN PRESENTING CELLS.

Deoxyribonucleic Acid (DNA): a double-stranded molecule that makes up the CHROMOSOMES in the center of a cell and that carries genetic information in the form of GENES. The genetic code utilized by DNA resides in the varying sequences of the four NUCLEOTIDE bases: ADENINE, GUANINE, THYMINE and CYTOSINE.

Depression: a CHRONIC or recurrent mental state characterized by hopelessness and lack of motivation and energy. Other major symptoms include loss of appetite and either excessive or inadequate sleep.

Dermatitis: INFLAMMATION of the skin.

Desensitization: gradually increasing the dose of a medicine in order to overcome potentially severe allergic reactions. Desensitization procedures are sometimes used when administering TRIMETHOPRIM/SULFAMETHOXAZOLE (Bactrim) for the first time to avoid a fever or skin reaction.



Dialysis: the separation of smaller molecules from larger molecules. Hemodialysis is a purification of the blood of persons whose kidneys no longer function.

Didanosine (ddI, Videx): a NUCLEOSIDE ANALOG from Bristol-Myers Squibb that inhibits infection of new cells by HIV. SIDE EFFECTS can include nerve damage in the hands and feet (PERIPHERAL NEUROPATHY) and damage to the pancreas (PANCREATITIS). Using ddI in combination with other drugs (including alcohol and DIDEOXYCYTIDINE [ddC]) can increase the risk of side effects. ddI must be taken on an empty stomach.

Dideoxycytidine (ddC, Zalcitabine, Hivid): a NUCLEOSIDE ANALOG from Hoffman La-Roche that inhibits infection of new cells by HIV. Possible SIDE EFFECTS include nerve damage in the hands and feet (PERIPHERAL NEUROPATHY) and sores in the mouth. The combination of ddI (DIDANOSINE) and ddC significantly increases the risk of peripheral neuropathy.


Diflucan: see FLUCONAZOLE.

Distal: further from the center of the body or from a central reference point.


Dorsal: relating to or located on or near the back.

Dorsal Fat Pad (Buffalo Hump): an enlargement at the lower, back-of-the-neck and shoulder region consisting of fat tissue. A form of fat redistribution associated with the use of ANTIRETROVIRALS. While it can be uncomfortable and unappealing, a dorsal fat pad is not a serious condition. Sometimes surgery or LIPOSUCTION can successfully remove a fat pad.

Dose-Escalating: describes a preliminary CLINICAL TRIAL in which the amount of a drug is either periodically increased or increased with each new trial ARM that is added. Used to determine how well a drug is tolerated in people and what its optimum dose might be, given the observed balance between ACTIVITY and SIDE EFFECTS.

Dose-Ranging: see DOSE-ESCALATING.

Double-Blinded: denotes a CLINICAL TRIAL in which neither the participants nor the doctors know who is receiving the EXPERIMENTAL DRUG and who is receiving the PLACEBO or standard comparison treatments. This method is believed to achieve the most accurate, generalizable results because neither the doctors nor the patients can affect the observed results with their psychological biases.

Down-Regulation: a reduction in the rate at which something happens.

Doxil (DOX-SL): a CYTOTOXIC CHEMOTHERAPY approved for KAPOSI'S SARCOMA (KS) consisting of a preparation of DOXORUBICIN encapsulated in LIPOSOMES which deliver significantly greater quantities of doxorubicin to the KS lesions while reducing the drug's SIDE EFFECTS. Side effects include nausea, vomiting, STOMATITIS, diarrhea and hair loss. Doxil causes a significant amount of NEUTROPENIA, which can be managed with GRANULOCYTE COLONY STIMULATING FACTOR (G-CSF).

Doxorubicin (Adriamycin): an INTRAVENOUS drug used in CHEMOTHERAPY for the treatment of cancer.


Dronabinol (Marinol): a drug containing synthetic tetrahydrocannabinol (THC), the psychoactive ingredient in CANNABIS. It is used to stimulate appetite and reduce nausea and vomiting from CHEMOTHERAPY.

Drug-Drug Interaction: the effects that may occur when two or more drugs are used together. Such effects include changes of absorption in the digestive tract, changes in rate of the drugs' breakdown in the liver, new or enhanced SIDE EFFECTS and changes in the drugs' ACTIVITY.

Drug Holiday: an intentional, temporary suspension of drug therapy. This term is now generally distinguished from a STRUCTURED TREATMENT INTERRUPTION.

Drug Resistance: see RESISTANCE.

Drug Resistance Assay: a test used to help determine whether a virus, like HIV, is susceptible to certain drugs. See also RESISTANCE, GENOTYPIC ASSAY, PHENOTYPIC ASSAY.

Drug Resistance Mutation: a MUTATION in a PATHOGEN's genetic makeup that confers RESISTANCE to one or more drugs.



Dual-Energy X-Ray Absorbtiometry (DEXA): a type of body scan that creates a computer-generated image of the body. It is used to assess bone status and fat distribution.

Dyspepsia: digestive upset, which may include flatulence, heartburn, nausea or vomiting.

Dysphagia: difficulty in swallowing.

Dysplasia: abnormal changes or growth of cells and tissues. See CERVICAL DYSPLASIA.

Dyspnea: shortness of breath or difficulty in breathing.

Dysthymia: a mood disorder.

© 2003 Gay Men's Health Crisis