ACQUIRED IMMUNODEFICIENCY SYNDROME (AIDS):
The most severe manifestation of infection with the Human Immunodeficiency Virus (HIV). The Centers for Disease Control and Prevention (CDC) lists numerous opportunistic infections and neoplasms (cancers) that, in the presence of HIV infection, constitute an AIDS diagnosis. There are also instances of presumptive diagnoses when a person's HIV status is unknown or not sought. This was especially true before 1985 when there was no HIV-antibody test. In 1993, CDC expanded the criteria for an AIDS diagnosis to include CD4+T-cell count at or below 200 cells per microliter in the presence of HIV infection. In persons (age 5 and older) with normally functioning immune systems, CD4+ T-cell counts usually range from 500-1,500 cells per microliter. Persons living with AIDS often have infections of the lungs, brain, eyes, and other organs, and frequently suffer debilitating weight loss, diarrhea, and a type of cancer called Kaposi's Sarcoma. See HIV Disease; Opportunistic Infections; AIDS Wasting Syndrome.
ACTIVE IMMUNITY:
Resistance resulting from previous exposure
to an infectious agent or antigen may be active and specific, as a result of naturally acquired infection or intentional vaccination (artificial active immunity), or it may be passive immunity.
ACUPUNCTURE:
A Chinese medical treatment involving the insertion of very fine sterile needles into the body at specific points according to a mapping of "energy pathways." Historically, acupuncture is one component of an overall program of Chinese medicine that includes theory, practice, diagnosis, physiology, and the use of herbal preparations. Acupuncture is used to control pain and to treat other conditions such as allergies or addiction withdrawal. See Alternative Medicine.
ACUTE HIV INFECTION:
The 4- to 7-week period of rapid viral replication immediately following exposure. The number of virions produced during primary infection is similar to that produced during several subsequent years of established, asymptomatic infection. An estimated 30 to 60 percent of individuals with primary HIV infection develop an acute syndrome characterized by fever, malaise, lymphadenopathy, pharyngitis, headache, myalgia, and sometimes rash. Following primary infection, seroconversion and a broad HIV-1 specific immune response occur, usually within 30 to 50 days. It was previously thought that HIV was relatively dormant during this phase. However, it is now known that during the time of primary infection, high levels of plasma HIV RNA can be documented.
ADENOPATHY:
Any disease involving or causing enlargement of glandular tissues, especially one involving the lymph nodes.
ADJUVANT:
An ingredient -- as in a prescription or solution -- that facilitates or modifies the action of the principal ingredient. May be used in HIV therapies or for HIV vaccines.
ADMINISTRATION:
(Route of Administration.) How a drug or therapy is introduced into the body. Systemic administration means that the drug goes throughout the body (usually carried in the bloodstream), and includes oral (by mouth), intravenous (injection into the vein, IV), intramuscular (injection into a muscle, IM), intrathecal (into the spinal canal), subcutaneous (beneath the skin, SQ), and rectal administrations. Local administration means that the drug is applied or introduced into the specific area affected by the disease, such as application directly onto the affected skin surface (topical administration). The effects of most therapies depend upon the ability of the drug to reach the affected area, thus the route of administration and consequent distribution of a drug in the body are important determinants of its effectiveness.
ADULT AIDS CLINICAL TRIALS GROUP (AACTG):
The largest HIV clinical trials organization in the world plays a major role in setting standards of care for HIV infection and opportunistic diseases related to HIV/AIDS in the United States and the developed world. The AACTG has been pivotal in providing the data necessary for the approval of therapeutic agents, as well as the treatment and prevention strategies, for many opportunistic infections and malignancies. The AACTG is composed of, and directed by, leading clinical scientists in HIV/AIDS therapeutic research and funded through the National Institute of Allergy and Infectious Diseases. Internet address: http://aactg.s-3.com/.
ADVERSE REACTION:
(Adverse Event.) An unwanted effect detected in clinical trial in participants. The term is used whether or not the effect can be attributed to the intervention under study. See Side Effects.
AEROSOLIZED:
A form of administration in which a drug, such as pentamidine, is turned into a fine spray or mist by a nebulizer and inhaled.
AFFECTED COMMUNITY:
Persons living with HIV and AIDS, and other related individuals including their families, friends, and advocates whose lives are directly influenced by HIV infection and its physical, psychological, and sociological ramifications.
AGENCY FOR HEALTH CARE POLICY AND RESEARCH (AHCPR):
An agency of the U.S. Department of Health and Human Services supporting activities to enhance health care services and improve access to them. Internet address: http://www.ahcpr.gov
AIDS DEMENTIA COMPLEX (ADC):
A degenerative neurological condition attributed to HIV infection, characterized by a group of clinical presentations including loss of coordination, mood swings, loss of inhibitions, and widespread cognitive dysfunctions. It is the most common central nervous system complication of HIV infection. Characteristically, it manifests itself after the patient develops major opportunistic infections or AIDS-related cancers. However, patients can also have this syndrome before these major systemic complications occur. The cause of ADC has not been determined exactly, but it may result from HIV infection of cells or inflammatory reactions to such infections.
AIDS DRUGS:
An online database service of the National Library of Medicine, with information about drugs undergoing testing against AIDS, AIDS-related complex, and related opportunistic diseases. Internet address: http://igm.nlm.nih.gov/.
AIDS DRUGS ASSISTANCE PROGRAMS (ADAP):
State-based programs funded in part by Title II of the Ryan White CARE Act that provide therapeutics (including devices necessary to administer pharmaceuticals) to treat HIV disease or prevent the serious deterioration of health, including treatment of opportunistic infections. ADAP formularies and eligibility criteria are determined state-by-state with a focus on serving low-income individuals.
AIDS EDUCATION AND TRAINING CENTERS (AETC):
The Health Resources and Services Administration (HRSA, see) supports the National AIDS Education and Training Centers (AETCs) Program. This is a network of 15 regional centers that conduct targeted, multidisciplinary HIV education and training programs for health care providers. The mission of these centers is to increase the number of health care providers who are effectively educated and motivated to counsel, diagnose, treat, and manage individuals with HIV infection and to assist in the prevention of high risk behaviors which may lead to infection. Internet address: http://www.seatec.emory.edu/.
AIDSLINE:
An online database service of the National Library of Medicine, with citations and abstracts covering the published scientific and medical literature on AIDS and related topics. Internet address: http://igm.nlm.nih.gov/.
AIDS-RELATED CANCERS:
Several cancers are more common or more aggressive in persons living with HIV. These malignancies include certain types of immune system cancers known as lymphomas, Kaposi's Sarcoma, and anogenital cancers that primarily affect the anus and the cervix. HIV, or the immune suppression it induces, appears to play a role in the development of these cancers.
AIDS-RELATED COMPLEX (ARC):
1. A term that has been used by some clinicians to describe a variety of symptoms and signs found in some persons living with HIV. These may include recurrent fevers, unexplained weight loss, swollen lymph nodes, diarrhea, herpes, hairy leukoplakia, and/or fungus infection of the mouth and throat. Also more accurately described as symptomatic HIV infection.
2. Symptoms that appear to be related to infection by HIV. They include an unexplained, chronic deficiency of white blood cells (leukopenia) or a poorly functioning lymphatic system with swelling of the lymph nodes (lymphadenopathy; see) lasting for more than 3 months without the opportunistic infections required for a diagnosis of AIDS. See AIDS Wasting Syndrome.
AIDS WASTING SYNDROME:
Involves involuntary weight loss of 10 percent of baseline body weight plus either chronic diarrhea (two loose stools per day for more than 30 days) or chronic weakness and documented fever (for 30 days or more, intermittent or constant) in the absence of a concurrent illness or condition other than HIV infection that would explain the findings.
ALKALINE PHOSPHATASE:
An enzyme normally present in certain cells within the liver, bone, kidney, intestine, and placenta. When the cells are destroyed in those tissues, more of the enzyme leaks into the blood, and levels rise in proportion to the severity of the condition. Measurement of this enzyme is used as an indication of the health of the liver.
ALOPECIA:
Loss of hair that frequently occurs in patients undergoing chemotherapy for cancer or suffering from other diseases, such as AIDS, where cell-killing, or cytotoxic, drugs are used.
ALPHA INTERFERON:
A protein -- one of three major classes of interferons -- that the body produces in response to infections. In persons who are HIV positive, elevated interferon levels are regarded as an indication of disease progression. Genetically engineered alpha interferon has been approved by the FDA as a treatment for Kaposi's Sarcoma. See Interferon.
ALTERNATIVE MEDICINE:
A broad category of treatment systems (e.g., chiropractic, herbal medicine, acupuncture, homeopathy, naturopathy, and spiritual devotions) or culturally based healing traditions such as Chinese, Ayurvedic, and Christian Science. Alternative medicines share the common characteristic of nonacceptance by the biomedical (i.e., mainstream Western) establishment. Alternative medicine is also referred to as "complementary medicine." The designation "alternative medicine" is not equivalent to holistic medicine, a narrower term. For more information contact the National Center for Complementary and Alternative Medicine Clearinghouse (NCCAM) online. Internet address: http://nccam.nih.gov/.
ALUM:
Potassium aluminum sulfate, or ammonium aluminum sulfate, used especially as an emetic (i.e., an agent that induces vomiting), an astringent (i.e., a substance that contracts tissues), and a styptic (i.e., a substance that tends to check bleeding by contracting the tissues or blood vessels).
ALVEOLAR:
Pertaining to the alveoli sac, the site of gas exchange in the lungs.
AMEBIASIS:
An inflammation of the intestines caused by infestation with Entameba histolytica (a type of ameba) and characterized by frequent, loose stools flecked with blood and mucus.
AMINO ACIDS:
Any of a class of nitrogen-containing acids. Some
22 amino acids are commonly found in animals and humans. Chains of amino acids synthesized by living systems are called polypeptides (up to about 50 amino acids) and proteins (more than 50 amino acids). See Peptide; Proteins.
AMPRENAVIR:
An FDA approved (04/15/99) protease inhibitor for use in combination with other antiretroviral agents for the treatment of HIV-1 infection in adults and children. Also called Agenerase.
ANALOG:
In chemistry, a compound with a structure similar to that of another compound but differing from it in respect to certain components or structural makeup, which may have a similar or opposite action metabolically.
ANAMNESTIC RESPONSE:
The heightened immunologic reaction elicited by a second or subsequent exposure to a particular antigen such as a pathogenic microorganism (e.g., bacterium, fungus).
ANAPHYLACTIC SHOCK:
A life-threatening allergic reaction characterized by a swelling of body tissues (including the throat) and a sudden decline in blood pressure.
ANEMIA:
A lower than normal number of red blood cells.
ANERGY:
1. The loss or weakening of the body's immunity to an irritating agent, or antigen. Anergy can be thought of as the opposite of allergy, which is an overreaction to a substance. The strength of the body's immune response is often quantitatively measured by means of a skin test where a solution containing an antigen known to cause a response, such as mumps or candida, is injected immediately under the skin. Patients may be so immunologically suppressed that they are unable to produce cutaneous (skin) delayed-type hypersensitivity reaction (DTH). Such patients will usually not test positive for tuberculosis on a tuberculin skin test (or Mantoux test). The lack of a reaction to these common antigens indicates anergy. 2. Researchers in cell culture have shown that CD4+T cells can be turned off by a signal from HIV that leaves them unable to respond to further immune system stimulation.
ANGIOGENESIS:
The process of forming new blood vessels. Angiogenesis is essential for the growth of tumors, especially Kaposi's Sarcoma.
ANGIOMATOSIS:
A condition characterized by the formation of a tumor that is composed chiefly of blood or lymphatic vessels. (See also Kaposi's Sarcoma).
ANOREXIA:
The lack or loss of appetite that leads to significant decline in weight.
ANTIBIOTIC:
A substance, especially one similar to those produced by certain fungi, that kills or inhibits the growth of microorganisms such as bacteria or fungi. Some antibiotics are used to treat infectious diseases.
ANTIBODIES:
Molecules in the blood or secretory fluids that tag, destroy, or neutralize bacteria, viruses, or other harmful toxins (see antigen). They are members of a class of proteins known as immunoglobulins, which are produced and secreted by B lymphocytes in response to stimulation by antigens. An antibody is specific to an antigen.
ANTIBODY-DEPENDENT CELL-MEDIATED CYTOTOXICITY (ADCC):
An immune response in which antibodies bind to target cells, identifying them for attack by the immune system.
ANTIBODY-MEDIATED IMMUNITY:
Also called humoral immunity. Immunity that results from the activity of antibodies in blood and lymphoid tissue (see lymphoid organs).
ANTIFOLATE:
An agent that inhibits intracellular (i.e., inside cells) production of folinic acid.
ANTIFUNGAL:
A substance that kills or inhibits the growth of a fungus.
ANTIGEN:
Any substance that antagonizes or stimulates the immune system to produce antibodies (i.e., proteins that fight antigens). Antigens are often foreign substances such as bacteria or viruses that invade the body.
ANTIGEN-PRESENTING CELL (APC):
The cell type that collects foreign material (see antigen) and digests it into pieces that can be recognized by the immune system. The APC presents the antigen to the helper T cells, the CD4+ T cells; this results in the initiation of expansion of an immune response targeted against the foreign material. APCs are B cells, macrophages, or dendritic cells (see entries for these terms).
ANTIIDIOTYPE:
An antibody that recognizes and binds to another antibody (idiotype).
ANTINEOPLASTIC:
Inhibiting or preventing the proliferation of tumor cells.
ANTIPROTOZOAL:
A substance that kills or inhibits the multiplication of single-celled microorganisms called protozoa.
ANTIRETROVIRAL AGENTS:
Substances used against retroviruses such as HIV.
ANTISENSE DRUGS:
An antisense, nucleic acid-related compound is the mirror image of the genetic sequence that it is supposed to inactivate. It is a synthetic segment of DNA or RNA that locks onto a strand of natural DNA or RNA with a complementary sequence of nucleotides. By binding to either the target DNA or RNA, the antisense drug prohibits the normal functioning and expression of the gene. This prevents the building of new virus particles or the infection of new host cells. The antisense drug fomivirsen has been approved by FDA for the treatment of CMV retinitis, a viral infection that often leads to blindness in patients with AIDS.
ANTITOXINS: Antibodies that recognize and inactivate toxins produced by certain bacteria, plants, or animals.
ANTIVIRAL:
A substance or process that destroys a virus or suppresses its replication (i.e., reproduction).
APHASIA:
Loss of ability to speak or understand speech.
APHTHOUS ULCER:
A painful oral or esophageal sore of unknown cause that has a deep eroded base. Aphthous ulcers are common in persons living with HIV and are treated with corticosteroids. Thalidomide -- a drug used in Europe as a sedative before it was discovered that it caused birth defects -- is an experimental, alternate therapy.
APOPTOSIS:
"Cellular suicide," also known as programmed cell death. HIV may induce apoptosis in both infected and uninfected immune system cells. Normally when CD4+ T cells mature in the thymus gland, a small proportion of these cells are unable to distinguish self from nonself. Because these cells would otherwise attack the body's own tissues, they receive a biochemical signal from other cells that results in apoptosis. See Tumor Necrosis Factor.
APPROVED DRUGS:
In the U.S., the Food and Drug Administration (FDA) must approve a substance as a drug before it can be marketed. The approval process involves several steps including preclinical laboratory and animal studies, clinical trials for safety and efficacy, filing of a New Drug Application by the manufacturer of the drug, FDA review of the application, and FDA approval/rejection of application.
ARM:
One group of participants in a comparative clinical trial, all of whom receive the same treatment. The other arm(s) receive(s) a different treatment regimen.
ASPERGILLOSIS:
A fungal infection -- resulting from the fungusAspergillus -- of the lungs that can spread through the blood to other organs. Symptoms include fever, chills, difficulty in breathing, and coughing up blood. If the infection reaches the brain, it may cause dementia. Amphotericin B is a recommended treatment. Itraconazole may be considered for less serious disease or for those who cannot tolerate amphotericin B.
ASSEMBLY AND BUDDING:
Names for a portion of the processes by which new HIV is formed in infected host cells. Viral core proteins, enzymes, and RNA (see ribonucleic acid) gather just inside the cell's membrane, while the viral envelope proteins aggregate within the membrane. An immature viral particle is formed and then pinches off from the cell, acquiring an envelope and the cellular and HIV proteins from the cell membrane. The immature viral particle then undergoes processing by an HIV enzyme called protease to become an infectious virus.
ASYMPTOMATIC:
Without symptoms. Usually used in the HIV/AIDS literature to describe a person who has a positive reaction to one of several tests for HIV antibodies but who shows no clinical symptoms of the disease.
ATAXIA:
Lack of muscular coordination.
ATTENUATED:
Weakened or decreased. For example, an attenuated virus can no longer produce disease but might be used to produce a vaccine.
AUTOANTIBODY:
1. An antibody that is active against some of the tissues of the organism that produced it. 2. An antibody directed against the body's own tissue.
AUTOIMMUNIZATION:
The induction in an individual of an immune response to its own cells (tissue).
AUTOINOCULATION:
Inoculation of a microorganism obtained by contact with a lesion on one's own body, producing a secondary infection.
AUTOLOGOUS:
Pertaining to the same organism or one of its parts; originating within an organism itself. For instance, donating your own blood for your future surgery is known as an autologous transfusion.
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