aspergillins Family of toxins (17 kDa) produced by Aspergillus. All are ribonucleases and disrupt protein biosynthesis. Includes alpha-sarcin, mitogillin, restric-tocin and Asp fl.
aspergillosis Lung disease caused by fungi of the genus Aspergillus.
Aspergillus A genus of common ascomycete fungi found in soil. Industrially important in production of organic acids and a popular fungus for genetic study (esp. A. niger).
aspirin Acetyl salicylate An analgesic, antipyretic and antiinflammatory drug. It is a potent cyclo-oxygenase inhibitor and blocks the formation of prostaglandins from arachi-donic acid. See COX-1.
association constant Ka; Kass Reciprocal of dissociation constant. A measure of the extent of a reversible association between two molecular species at equilibrium.
astacin A zinc endopeptidase from crayfish (Astacus), the prototype for the astacin family of metalloendopeptidases. Family includes BMP-1, Meprin A, stromelysin 1 and thermolysin.
astaxanthin 3, 3'-Dihydroxy-4,4'-diketo-b-carotene A naturally occurring red carotenoid pigment with antioxidant properties. Most crustaceans are tinted red by accumulated astaxanthin, and the pink flesh of a healthy salmon is due to accumulated astaxanthin. This is added to feed in fish farms to substitute for the astaxanthin in the diet of a wild salmon.
aster Star-shaped cluster of microtubules radiating from the polar microtubule-organizing centre at the start of mitosis.
asthma Inflammatory disease of the airways involving marked eosinophil infiltration and remodelling of the airways. Attacks can be triggered by allergic responses, physical exertion, inhaled chemicals or stress, and involve wheezing, breathlessness and coughing.
astrin A microtubule-associated protein (134 kDa) that localizes with mitotic spindles in M-phase and is essential for progression through mitosis, although astrin's function is unclear. Present in most tissues but highly expressed in the testis (see ODF).
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If you suffer with asthma, you will no doubt be familiar with the uncomfortable sensations as your bronchial tubes begin to narrow and your muscles around them start to tighten. A sticky mucus known as phlegm begins to produce and increase within your bronchial tubes and you begin to wheeze, cough and struggle to breathe.