| beta-adrenergic receptors | Adrenergic receptor's in effector tissues capable of selective activation and blockade by drugs; conceptually derived from the ability of certain agents, such as propranolol, to block only some adrenergic receptor's and of other agents, such as isoproterenol, to activate only the same adrenergic receptor's. Such receptor's are designated as beta-receptors. Their activation results in physiological responses such as increases in cardiac rate and force of contraction (b1), and relaxation of bronchial and vascular smooth muscle (b2). (05 Mar 2000) |
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| beta-adrenoreceptor antagonist | A class of drugs that compete with beta-adrenergic agonists for available receptor sites; some compete for both b1 and b2 receptors (e.g., propranolol) while others are primarily either b1 (e.g., metoprolol) or b2 blockers; used in the treatment of a variety of cardiovascular diseases where beta-adrenergic blockade is desirable. Synonym: beta-adrenergic receptor blocking agent, beta-adrenoreceptor antagonist, beta-blocker. (05 Mar 2000) |
| beta-alanine | <chemical> Beta-alanine. An amino acid formed in vivo by the degradation of dihydrouracil and carnosine. Since neuronal uptake and neuronal receptor sensitivity to beta-alanine have been demonstrated, the compound may be a false transmitter replacing gaba. A rare genetic disorder, hyper-beta-alaninaemia, has been reported. Chemical name: beta-Alanine (12 Dec 1998) |
| beta-alanine-pyruvate aminotransferase | <enzyme> An enzyme that reversibly transfers the amino group of beta-alanine to paruvate, thus producing l-alanine and malonate saemialdehyde. A deficiency of this enzyme is believed to be the cause of hyper-beta-alaninaemia. (05 Mar 2000) |
| beta-alanyl-arginine hydrolase | <enzyme> Also hydrolyzes carnosine, at a lower rate; requires mn2+; inhibited by bestatin; stabilised by sulfhydryl reagents Registry number: EC 3.4.13.- Synonym: ala-arg hydrolase (26 Jun 1999) |
| beta alcoholism | Jellinek's term for the physical complaints associated with excessive use of alcohol, such as polyneuropathy, gastritis, and liver cirrhosis. (05 Mar 2000) |
| beta-allocortol | 5alpha-Pregnane-3a,11b,17,20b,21-pentaol;the 20b isomer of alpha-allocortol and 5a enantiomer of beta-cortol; a metabolite of hydrocortisone found in urine. (05 Mar 2000) |
| beta-allocortolone | 3a,17,20b,21-Tetrahydroxy-5alpha-pregnane-11-one;the 20b isomer of alpha-allocortolone and 5a enantiomer of beta-cortolone; a metabolite of hydrocortisone found in urine. (05 Mar 2000) |
| beta-allopregnanediol | The 5alpha-pregnane-3b,20a(and b)-diols; both are metabolites of progesterone and adrenocortical hormones; found in urine. (05 Mar 2000) |
| beta-aminoisobutyrate:pyruvate aminotransferase | Beta-aminosiobutyrate:pyruvate transaminase;an enzyme that catalyses the reversible transfer of an amino group from beta-aminoisobutyrate to pyruvate, producing l-alanine and methylmalonate saemialdehyde. A step in valine degradation. A deficiency of beta-aminoisobutyrate:pyruvate aminotransferase results in hyper-beta-aminoisobutyric aciduria. (05 Mar 2000) |
| beta-aminoisobutyric acid | 3-Amino-2-methylpropionic acid;an end product of thymine catabolism; high urinary levels (200-300 mg/day) have been noted in some individuals, either from some disease process or following a genetic pattern. (05 Mar 2000) |
| beta-aminoisobutyric acid oxidase | <enzyme> Fad-stimulated, probably forms methylmalonylsaemialdehyde Registry number: EC 1.4.3.- Synonym: baib-oxidase (26 Jun 1999) |
| beta-amylase | <enzyme> An enzyme that catalyses the hydrolysis of 1,4-alpha-glycosidic linkages in starch, glycogen, and related polysaccharides and oligosaccharides so as to remove successive beta-maltose units from the non-reducing ends of the chains. Chemical name: 1,4-alpha-D-Glucan maltohydrolase Registry number: EC 3.2.1.2 (12 Dec 1998) |
| beta-amyloid | <protein> The protein which forms thick deposits, or plaques, in the brains of people with Alzheimer's disease, a disease where memory skills gradually deteriorate with age. (13 Nov 1997) |
| beta angle | The angle formed by a line connecting the bregma and hormion meeting the radius fixus. (05 Mar 2000) |