Barbados leg: See ELEPHANTIASIS. Baridol: See BARIUM SULFATE. barium study: (1) A test used in examining the gastrointestinal tract. (2) Any test involving the use of barium sulfate as a radiopaque (prohibiting the passage of X rays and other forms of radiant energy) contrast medium for distinguishing anatomical areas in the gastrointestinal tract. barium sulfate: (1) An opaque substance that is swallowed to assist in the examination of the stomach and intestines. (2) An odorless, tasteless, fine, white powder used as a contrast medium in roentgenography (X rays) of the gastrointestinal tract. The trade names are Barosperse, Esophotrast, and Baridol. Also called BLANC FIXE. Barosperse: See BARIUM SULFATE. Bartonella henselae: A species of gram-negative bacteria that is the causative agent of bacillary angiomatosis. It can also cause cat-scratch disease in AIDS patients and other immunocompromised patients. basal cell carcinoma: A tumor of the skin that rarely metastasizes. Usually, it manifests as a small, shiny papule. The lesion grows until it appears as a whitish border surrounding a central ulcer. baseline: A known or initial observation or value used for comparison in measuring the response to experimental intervention or stimulus (e.g., a person's T4-cell count upon entering a clinical trial). basophil: (1) A cell or part of a cell that stains readily with basic dyes. (2) An endocrine found in the anterior lobe of the pituitary gland. It produces the substance that stimulates the adrenal cortex to secrete adrenal cortical hormone. (3) A granular leukocyte charac-

terized by the possession of coarse, bluish-black granules of varying size that stain intensely with basic dyes. bathhouse: A facility resembling a public bathhouse, but used primarily for anonymous sexual encounters. Generally equipped with both private and public rooms and operated for profit. Bathhouses came under heavy fire in 1983 after it was established that the human immuno-deficiency virus is transmitted through sexual intercourse. BCG vaccine: A tuberculosis vaccine made from a freeze-dried preparation of a live strain of Mycobacterium bovis. Regularly used for the vaccination of children only in areas with a high incidence rate of tuberculosis in the United States. It is recommended only for immunizing high-risk persons. bedsore: See DECUBITUS ULCER. bee propolis: Resin-like substance obtained from beehives, full of substances thought to have antimicrobial or antimycotic activity when applied topically. behavior modification: A technique employed to alter animal or human behavior through application of the principles of conditioning. Rewards and reinforcements, or punishments, are administered to establish desired habits or patterns of behavior. beneficiary: Person or persons designated to receive proceeds from an estate upon the death of an individual. benign: (1) Not recurrent or progressive. (2) The opposite of malignant.