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Subject: b
Date: Thu, 12 Oct 95 23:34 PDT (162 lines of text)

BACTERICIDAL:

Capable of killing bacteria.

BACTERIOSTATIC:

Capable of inhibiting reproduction of bacteria.

BACTERIUM:

A microscopic organism composed of a single cell. Many bacteria can cause disease in humans.

BACULOVIRUS:

A virus of insects used in the production of some HIV vaccines. See also Vaccine.

BASELINE:

1. Information gathered at the beginning of a study from which variations found in the study are measured. 2. A known value or quantity with which an unknown is compared when measured or assessed.

BASOPHIL:

A type of white blood cell, also called a granular leukocyte, filled with granules of toxic chemicals that can digest microorganisms. Basophils, as well as other types of white blood cells, are responsible for the symptoms of allergy. The granules stain blue when exposed to a basic dye for microscopic examination.

B CELL LYMPHOMA:

See Lymphoma.

B CELLS:

See B Lymphocytes.

BILIRUBIN:

1. A bile pigment whose measurement can be used as an indication of the health of the liver. 2. A substance released from old or damaged red blood cells. Small amounts of bilirubin normally enter the bloodstream and circulate until they reach the liver and then into the bowel, where bilirubin is further broken down and excreted. The normal value is 0.1 to 1.5 milligrams per liter of blood.

BINDING ANTIBODY:

As related to HIV infection:

An antibody that attaches to some part of the HIV virus. Binding antibodies may or may not adversely affect the virus.

BIOLOGICAL RESPONSE MODIFIERS (BRMs):

Substances, either natural or synthesized, that boost, direct or restore normal immune defenses. BRMs include interferons, interleukins, thymus hormones and monoclonal antibodies. See also Interferon; Interleukin-2; Monoclonal Antibody; Thymus.

BIOPSY:

The surgical removal of a piece of tissue from a living subject for microscopic examination to make a diagnosis (for example, to determine whether abnormal cells such as cancer cells are present).

BIOTECHNOLOGY:

1. The use of living organisms or their products to make or modify a substance. These include recombinant DNA techniques (also referred to as genetic engineering) and hybridoma technology. 2. The industrial application of the results of biological research, particularly in fields such as recombinant DNA or gene splicing, which permits the production of synthetic hormones or enzymes by combining genetic material from different species.

BLINDED STUDY:

A clinical trial in which participants are unaware as to whether or not they are in the experimental or control arm of the study.

BLOOD BRAIN BARRIER:

The barrier between brain blood vessels and brain tissues whose effect is to restrict what may pass from the blood into the brain.

B LYMPHOCYTES (B CELLS):

One of the two major classes of lymphocytes. During infections, these cells are transformed into plasma cells that produce large quantities of antibody directed at specific pathogens. This transformation occurs through interactions with various types of T cells and other components of the immune system. In persons with AIDS, the functional ability of both the B and the T lymphocytes is damaged, with the T lymphocytes being the principal site of infection by the HIV virus. See also Lymphocyte; T Cells.

BODY FLUIDS:

Any fluid in the human body, such as blood, urine, saliva, sputum (spit), tears, semen, mother's milk or vaginal secretions. Only blood, semen, mother's milk and vaginal secretions have been linked directly to the transmission of the HIV virus.

BONE MARROW:

Soft tissue located in the cavities of the bones where blood cells such as erythrocytes, leukocytes and platelets are formed. See also Erythrocytes; Leukocytes; Platelets.

BOOSTER:

A second or later dose of a vaccine given to increase the immune response to the original dose. See also Vaccine.

BRANCHED DNA ASSAY:

A sensitive, rapid test that can be used to monitor the amount of HIV in a patient's bloodstream (i.e., the viral burden). See also Viral Burden.

BREAKTHROUGH INFECTION:

An infection, caused by the infectious agent the vaccine is designed to protect against, that occurs during the course of a vaccine trial. These infections may be caused by exposure to the infectious agent before the vaccine has taken effect, or before all doses of the vaccine have been given. Breakthrough infections also occur in trial participants receiving placebos.

BRONCHOSCOPY:

Visual examination of the bronchial passages of the lungs through a tube of an endoscope inserted into the upper lungs or extraction of material from the lungs by means of a bronchoscope. See also Endoscopy.

BUDDING:

See Assembly and Budding.

BURKITT'S LYMPHOMA:

A lymphatic cancer that involves not only the lymphatic and the associated reticuloendothelial system, but also other body tissues. This disease, which is most common in Central Africa, is thought to be possibly caused by the Epstein-Barr virus. Also called African lymphoma, Burkitt's tumor. See also Epstein-Barr Virus; Lymph; Reticuloendothelial Cells.