Dictionary

anti-citrulline antibody See citrulline antibody.

anticipation The progressively earlier appearance and increased severity of a disease from generation to generation. The phenomenon of anticipation was once thought to be an artifact, but a biological basis for it has been discovered in a number of genetic disorders, such as myotonic dystrophy and Huntington disease.

anticholinergic Opposing the actions of the neurotransmitter acetylcholine. Anticholinergic drugs inhibit the transmission of parasympathetic nerve impulses, thereby reducing spasms of smooth muscles (for example, muscles in the bladder). Side effects of anticholinergic medications include dry mouth and related dental problems, blurred vision, tendency toward overheating (hyperpyrexia), and in some cases, dementia-like symptoms.

antibody A specialized immune protein (an immunoglobulin) produced because of the introduction of an antigen into the body. An antibody possesses the remarkable ability to combine with the antigen that triggered its production. The production of antibodies is a major function of the immune system and is carried out by a type of white blood…

antibiotic resistance The ability of bacteria and other microorganisms to resist the effects of an antibiotic to which they were once sensitive. Antibiotic resistance is a major concern of overuse of antibiotics. Also known as drug resistance.

antibiotic A substance produced by one microorganism that selectively inhibits the growth of another. Synthetic antibiotics, usually chemically related to naturally occurring antibiotics, are made to accomplish comparable tasks. Antibiotics are used to treat bacterial infections. See also cephalosporin antibiotics; penicillin.

anti-angiogenesis drug A drug, such as angiostatin or endostatin, that halts the development of new blood vessels (angiogenesis).

anthrax toxin The toxic substance secreted by the bacterium Bacillus anthracis, the cause of the disease anthrax.

anthrax immunization A series of six injections over a 6-month period, followed by annual booster shots, given to military personnel and others (including veterinarians who work with large animals) who are at high risk of anthrax exposure.

anthrax, inhalation Anthrax infection of the lungs, also known as pulmonary anthrax, that is due to the inhalation of anthrax spores. The inhaled spores multiply rapidly in the lymph nodes in the chest. A person infected with inhalation anthrax experiences local bleeding and tissue death (necrosis) in these lymph nodes, and the disease spreads to…

anthrax, gastrointestinal Anthrax infection of the gastrointestinal tract, now very rare but deadly. Gastrointestinal anthrax is caused by eating meat that is contaminated with the bacterium Bacillus anthracis.

anthrax, cutaneous Anthrax infection of the skin. The most common form of anthrax, cutaneous anthrax starts as a red-brown raised spot that enlarges and has redness, blistering, and hardening in the area of the spot. The center of the spot then shows an ulcer crater with blood-tinged drainage and the formation of a black crust…