| gamma-linolenic acid | <chemical> (z,z,z)-6,9,12-octadecatrienoic acid. An omega-6 fatty acid produced in the body as the delta 6-desaturase metabolite of linoleic acid. It is converted to dihomo-gamma-linolenic acid, a biosynthetic precursor of monoenoic prostaglandins such as pge1. Chemical name: 6,9,12-Octadecatrienoic acid, (Z,Z,Z)- (12 Dec 1998) |
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| vanadic acid | An acid, H3VO4, derived from vanadium, forming salts with various bases. (05 Mar 2000) |
| vanillic acid | <chemical> A flavoring agent. It is the intermediate product in the two-step bioconversion of ferulic acid to vanillin. Chemical name: Benzoic acid, 4-hydroxy-3-methoxy- (12 Dec 1998) |
| vanillylmandelic acid | Misnomer for 4-hydroxy-3-methoxymandelic acid (a,3-dihydroxy-2-methoxybenzeneacetic acid);the major urinary metabolite of adrenal and sympathetic catecholamines (e.g., from both epinephrine and norepinephrine); elevated in most patients with pheochromocytoma. Acronym: VMA (05 Mar 2000) |
| vanillylmandelic acid test | A test for catecholamine-secreting tumours (pheochromocytoma and neuroblastoma) performed on a 24-hr urine specimen; it is based on the fact that vanillylmandelic acid is the major urinary metabolite of norepinephrine and epinephrine. Synonym: 3-methoxy-4-hydroxymandelic acid test, VMA test. (05 Mar 2000) |
| vanilmandelic acid | <chemical> Chemical name: Benzeneacetic acid, alpha,4-dihydroxy-3-methoxy- (12 Dec 1998) |
| Palmer acid test for peptic ulcer | In duodenal ulcer, the administration of acid by duodenal tube causes severe pain. (05 Mar 2000) |
| palmitic acid | <biochemistry> One of the most widely distributed of fatty acids. The palmitoyl residue is one of the common acyl residues of membrane phospholipids. It is also found as a thioester attached to cystein residues on some membrane proteins. The proteins so modified are often transmembrane proteins and the modified residue is on the cytoplasmic surface of the membrane. The specificity of the transferase for the acyl residue is not high and both stearoyl and oleoyl residues can replace the palmitoyl residue. Compare: myristoylation. (18 Nov 1997) |
| palmitoleic acid | 9-Hexadecenoic acid;a monounsaturated 16-carbon acid; one of the common constituents of the triacylglycerols of human adipose tissue. Synonym: zoomaric acid. (05 Mar 2000) |
| Rambourg's periodic acid-chromic methenamine-silver stain | <technique> A stain for glycoproteins, used with an electron microscope, adapted from the Gomori-Jones periodic acid-methenamine-silver stain; it produces silver deposits in mature saccules of the Golgi apparatus, lysosomal vesicles, cell coat, and basement membranes. (05 Mar 2000) |
| p-aminobenzoic acid | A factor in the vitamin B complex, a part of all folic acids and required for its formation; neutralises the bacteriostatic effects of the sulfonamides since it furnishes an essential growth factor for bacteria, the utilization with which the sulfonamides interfere; used as an ultraviolet screen in lotions and creams. Synonym: paraaminobenzoic acid, vitamin Bx. Acronym: PABA (05 Mar 2000) |
| p-aminohippuric acid | <chemical> N-(4-aminobenzoyl)glycine. A diagnostic aid used as the sodium salt in renal function tests. Chemical name: Glycine, N-(4-aminobenzoyl)- (12 Dec 1998) |
| p-aminohippuric acid synthase | <enzyme> An enzyme in the liver that catalyses the synthesis of p-aminohippuric acid from p-aminobenzoic acid (or the CoA-derivative) and glycine. It may be identical with glycine acyltransferase. Acronym: PAH (05 Mar 2000) |
| p-aminosalicylic acid | <chemical> 4-amino-2-hydroxybenzoic acid. An antitubercular agent often administered in association with isoniazid. The sodium salt of the drug is better tolerated than the free acid. Pharmacological action: antitubercular agents. Chemical name: Benzoic acid, 4-amino-2-hydroxy- (12 Dec 1998) |
| gastric acid | Hydrochloric acid present in gastric juice. (12 Dec 1998) |