| oxygen radical | <chemistry> Any oxygen species that carries an unpaired electron (except free oxygen). Examples are the hydroxyl radical and the superoxide anion. These radicals are very powerful oxidizing agents and cause structural damage to proteins and nucleic acids. They mediate the damaging effects of ionising radiation. (18 Nov 1997) |
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| oxygen radioisotopes | Unstable isotopes of oxygen that decay or disintegrate emitting radiation. O atoms with atomic weights 13, 14, 15, 19, and 20 are radioactive oxygen isotopes. (12 Dec 1998) |
| oxygen tent | A transparent enclosure, suspended over the bed and enclosing the patient, used to supply a high concentration of oxygen. (05 Mar 2000) |
| oxygen therapy | Treatment in which an increased concentration of oxygen is made available for breathing, through a nasal catheter, tent, chamber, or mask. (05 Mar 2000) |
| oxygen toxicity | A body disturbance resulting from breathing high partial pressures of oxygen; characterised by visual and hearing abnormalities, unusual fatigue while breathing, muscular twitching, anxiety, confusion, incoordination, and convulsions; although the mechanism for development of the condition is obscure, a disruption of enzymatic activity is likely, perhaps as a result of free radical formation. Synonym: oxygen poisoning. (05 Mar 2000) |
| oxygen utilization coefficient | The extraction coefficient for oxygen in any given tissue. (05 Mar 2000) |
| lactacid oxygen debt | That part of an oxygen debt represented by the production of lactic acid by anaerobic glycolysis during exercise and, therefore, by the need to eliminate it by oxidative metabolism during recovery. (05 Mar 2000) |
| fructosyl aminocaproate-oxygen oxidoreductase | <enzyme> Catalyses conversion of amadori products to fructosamine; isolated from pseudomonas Registry number: EC 1.5.3.- Synonym: amadoriase, 1-deoxyfructosyl alkyl amino acid oxidase, fructosyl amino acid oxidase, faod enzyme (26 Jun 1999) |
| abnormal cleavage of cardiac valve | Congenital malformation of a valve leaflet with a defect extending from the free margin. (05 Mar 2000) |
| Amussat's valve | A series of crescentic folds of mucous membrane in the upper part of the cystic duct, arranged in a somewhat spiral manner. Synonym: plica spiralis ductus cystici, Amussat's valve, Heister's valve, spiral valve of cystic duct, valvula spiralis. (05 Mar 2000) |
| anterior cusp of atrioventricular valve | The anterior leaflet or valvule of either the tricuspid or mitral valves. Synonym: cuspis anterior valvae atrioventricularis dextrae/sinistrae. (05 Mar 2000) |
| anterior urethral valve | A crescentic horizontal fold in the proximal spongy urethra. (05 Mar 2000) |
| aortic valve | The heart valve that divides the left ventricle and the aorta. The aortic valve opens during left ventricular contraction and then closes to prohibit the backwash of oxygenated blood from the aorta into the ventricle. The aortic valve has 3 valve cusps. (27 Sep 1997) |
| aortic valve insufficiency | Backflow of blood from the aorta into the left ventricle, owing to imperfect functioning of the aortic semilunar valve. (12 Dec 1998) |
| aortic valve prolapse | The downward displacement of the cuspal material (misalignment of the cusps) below a line joining points of attachment of the aortic valve leaflets. The prolapsed cusp may occlude the ventricular septal defect during ventricular diastole. (12 Dec 1998) |