| PCA | para-chloramphetamine; parietal cell antibody; passive cutaneous anaphylaxis; patient care assistant... |
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| PGA | pepsinogen A; phosphoglyceric acid; polyglandular autoimmune [syndrome]; prostaglandin A; pteroylglu... |
| PLA | peripheral laser angioplasty; phenyl lactate; phospholipase A; phospholipid antibody; placebo therap... |
| PPA | palpation, percussion, auscultation; pepsin A; phenylpropanolamine; phenylpyruvic acid; Pittsburgh p... |
| RDDP | ribonucleic acid-dependent deoxynucleic acid polymerase |
| valproic acid | This drug is used to treat seizures. It may cause liver damage and has side effects such as drowsiness, nausea, and hair loss. (09 Oct 1997) |
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| gamma aminobutyric acid | <biochemistry> An important amino acid which functions as the most prevalent inhibitory neurotransmitter in the central nervous system. Gamma aminobutyric acid works in partnership with a derivative of Vitamin B-6, pyridoxine, to cross from the axons to the dendrites through the synaptic cleft, in response to an electrical signal in the neuron and inhibits message transmission. This helps control the nerve cells from firing too fast, which would overload the system. The action of gamma aminobutyric acid decreases epileptic seizures and muscle spasms by inhibiting electrical signals in this manner. Studies have shown that the site of action in the brain of benzodiazepams, including Valium, is directly coupled to the brain receptor for gamma aminobutyric acid. Acronym: GABA (05 Jan 1998) |
| gamma aminobutyric acid receptor | <physiology> Ligand gated chloride ion channel forming receptor opened by gamma aminobutyric acid. Two distinct types: A and B. A receptor: One of a family of neurotransmitter receptors with fast intrinsic ion channels that includes the glycine receptor and the nicotinic acetylcholine receptor. Distinct from another major receptor family, the muscarininc acetylcholine receptor and rhodopsin, with no intrinsic ion channel. The A receptor is specifically blocked by bicuculline. It consists of two pairs of protein chains forming an A2B2 complex, the A chains bind benzodiazepine and the B chains bind GABA. The 4 subunits are thought to form a tight group with the chloride channel in the middle. There is considerable similarity between the amino acid sequences of the receptor subunits and those of the nicotinic acetylcholine receptor suggesting that both receptors are derived from some evolutionary ancestor. See: amino acid receptor superfamily. B receptor: Brain receptor (80 kD) for the inhibitory neurotransmitter gamma amino butyric acid. Differs from the A receptor both in agonist specificity (baclofen is a specific agonist) and its effects on cells. It modulates intracellular calcium levels through a Go mediated effect on N type calcium channels and also lowers intracellular cAMP levels by an effect on adenylyl cyclase, thereby reducing the secretion of catecholamines. (05 Jan 1998) |
| 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) |
| 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) |