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 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 toxin The toxic substance secreted by the bacterium Bacillus anthracis, the cause of the disease anthrax.
anti-angiogenesis drug A drug, such as angiostatin or endostatin, that halts the development of new blood vessels (angiogenesis).
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.
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.
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…
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.
ankle A complex structure made up of two joints: the true ankle joint and the subtalar joint. The ankle’s movement is constrained and controlled by ligaments, including the anterior tibiofibular ligament, which connects the tibia to the fibula; the lateral collateral ligaments, which attach the fibula to the calcaneus to give the outside of the…
ankle joint A joint that is composed of three bones: the tibia, the fibula, and the talus. The ankle joint is responsible for the up-and-down motion of the foot. The subtalar joint is under the ankle joint, and it consists of the talus on top and calcaneus on the bottom. The subtalar joint is responsible…
ankle-foot orthosis A brace, usually made of plastic, that is worn on the lower leg and foot to support the ankle, hold the foot and ankle in the correct position and correct foot drop. Abbreviated AFO. Also known as foot drop brace.
ankyloglossia A minor birth defect in which the flap of membrane attached to the underside of the tongue (frenulum) is too short. This shortened frenulum limits the mobility of the tongue. Ankyloglossia is also called tongue tie, from the folk belief that the anomaly causes feeding and speech problems. A child cannot feed or speak…