| alpha rhythm | Brain waves in the encephalogram which have a frequency of 8 to 13 per second. They are typical of the normal person awake and in a quiet resting state, and occur principally in the occipital region. (12 Dec 1998) |
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| alpha-ribazole | 1-alpha-d-ribofuranosyl-5,6-dimethylbenzimidazole;the benzimidazole nucleoside in vitamin B12. (05 Mar 2000) |
| alpha-santonin-1,2-reductase | <enzyme> From pseudomonas cichorii s.; catalyses the reduction of the 1,2-double bond of santonin; NADH or NADPH dependent Registry number: EC 1.3.1.- Synonym: santonin 1,2-reductase (26 Jun 1999) |
| alpha-sarcin | A fungal toxin that acts on the large subunit of rRNA and inactivates the ribosome. (05 Mar 2000) |
| alpha-streptococci | Streptococci that form a green variety of reduced haemoglobin in the area of the colony on a blood agar medium. (05 Mar 2000) |
| alpha substance | A filamentous plasmatic material, beaded with granules, demonstrable by means of vital staining in the immature red blood cells. Synonym: alpha substance, filar mass, filar substance, substantia reticularis, substantia reticulofilamentosa. Synonym: reticular formation. (05 Mar 2000) |
| Alpha tests | A set of paper and pencil-administered mental tests first used in the United States Army in 1917-1918 to determine the mental ability of literate recruits; the set includes 8 different types of tests: i.e., directions, arithmetical problems, practical judgement, synonyms and antonyms, disarrayed sentences, number series completions, analogies, and information; they are designed especially for testing large groups of individuals simultaneously, and for rapid machine scoring; distinguished from the Army Beta tests, a complementary set for administration to recruits who could not read or write English, in which the instructions are given in signs and the test material is pictorial. See: Beta tests. Synonym: Army Alpha tests. (05 Mar 2000) |
| alpha thalassaemia | <haematology> A condition characterised by the reduced synthesis of the alpha chain of haemoglobin due to abnormality in one of two or more genes that code for the synthesis of alpha-globin chains. The severity of this condition can vary from mild anaemia to death, depending on the number of genes deleted. Heterozygous state: severe type, thalassaemia minor with 5 to 15% of Hb Barts at birth, only traces of Hb Barts in adult; mild type, 1 to 2% of Hb Barts at birth, not detectable in adult. Homozygous state: severe type, erythroblastosis foetalis and foetal death, only Hb Barts and Hb H present; mild type not clinically defined. See: haemoglobin H. (05 Mar 2000) |
| alpha-tocopherol | <chemical> A light yellow, viscous, odourless, oily liquid that deteriorates on exposure to light, is obtained from wheat germ oil or by synthesis, biologically exhibits the most vitamin E activity of the alpha-tocopherol's, and is an antioxidant retarding rancidity by interfering with the autoxidation of fats. Prepared from natural phytol, it is called 2-ambo-alpha-tocopherol; from synthetic phytol, all-rac-alpha-tocopherol or synt-alpha-tocopherol; also available are d-alpha-tocopheryl acetate, dl-alpha-tocopheryl acetate, d-alpha-tocopheryl acid succinate, and d-alpha-tocopheryl acetate concentrate. One of several forms of vitamin E. Chemical name: 2,5,7,8-tetramethyl-2-(4',8',12'-trimeth yltridecyl)-6-chromanol; 5,7,8-trimethyltocol Synonym: vitamin E. (14 Aug 2000) |
| alpha-tubulin acetylase | <enzyme> From chlamydomonas flagella; catalyses the acetylation of alpha-tubulin-l-lysine in the presence of acetyl-CoA to yield CoA and alpha-tubulin n(epsilon)-acetyl-l-lysine Registry number: EC 2.3.1.108 Synonym: alpha-tubulin acetyltransferase (26 Jun 1999) |
| alpha units | Cytoplasmic glycogen granules arranged in rosettes. (05 Mar 2000) |
| alpha viruses | <virology> These are the major viruses in the Togavirus group and include eastern and western equine encephalitis viruses, the Sindbis virus and the Semliki Forest virus. The last two viruses are being researched as vectors for expressing heterologous genes. (09 Oct 1997) |
| alpha wave | Brain waves in the encephalogram which have a frequency of 8 to 13 per second. They are typical of the normal person awake and in a quiet resting state, and occur principally in the occipital region. (12 Dec 1998) |
| androstenedione 17-alpha-oxidoreductase | <enzyme> Forms epitestosterone; was mapped to testosterone dehydrogenases (85-93); index medicus see under 17-hydroxysteroid dehydrogenases (85-90) Registry number: EC 1.1.1.- Synonym: steroid 17alpha oxidoreductase, androstenedione 17-oxidoreductase (26 Jun 1999) |
| aryl-alpha-mannosidase | <enzyme> Act on p-nitrophenyl-alpha-d-mannopyranoside Registry number: EC 3.2.1.- Synonym: aryl-alpha-mannosidase a, aryl-alpha-mannosidase b (26 Jun 1999) |