| P-A conduction time | See: atrioventricular conduction. (05 Mar 2000) |
|---|---|
| P-A interval | The time from onset of the P wave to the initial rapid deflection of the A wave in the His bundle electrogram (normally 25-45 msec); it represents the intra-atrial conduction time. (05 Mar 2000) |
| p-aminoazobenzene | <chemical> Used in the form of its salts as a dye and as an intermediate in manufacture of acid yellow, diazo dyes, and indulines. Pharmacological action: dyes. Chemical name: Benzenamine, 4-(phenylazo)- (12 Dec 1998) |
| 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-aminohippurate clearance | A good measure of renal plasma flow, which it slightly underestimates; when a low plasma concentration of p-aminohippurate (PAH) is maintained by intravenous infusion, the kidney extracts and excretes almost all of the PAH from the plasma before it reaches the renal vein. (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-aminopropiophenone | <drug> An antidote for cyanide poisoning. Chemical name: 1-(4-Aminophenyl)-1-propanone Acronym: PAPP (21 Jun 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) |
| p-azobenzenearsonate | <chemical> 4,4'-azodibenzenearsonic acid. A hapten capable of eliciting both antibody formation and delayed hypersensitivity when bound to aromatic amino acids, polypeptides or proteins. It is used as an immunologic research tool. Chemical name: Arsonic acid, (azodi-4,1-phenylene)bis- (12 Dec 1998) |
| p-chloral | A polymer of chloral obtained by prolonged contact with sulfuric acid; it has properties similar to those of chloral hydrate. Synonym: metachloral, p-chloral, trichloral. (05 Mar 2000) |
| p-chloroamphetamine | <chemical> Chlorinated analog of amphetamine. Potent neurotoxin that causes release and eventually depletion of serotonin in the CNS. It is used as a research tool. Pharmacological action: serotonin agents. Chemical name: Benzeneethanamine, 4-chloro-alpha-methyl- (12 Dec 1998) |
| p-chloromercuribenzoate | Organic mercury compound (ClHgC6H4COO-, ClHgBzO-) that reacts with -SH groups of proteins; an inhibitor of action of those proteins (enzymes) that depend on -SH reactivity. See: p-mercuribenzoate. Acronym: PCMB (05 Mar 2000) |
| p-chlorophenol | A disinfectant effective against most Gram-negative organisms; also available as camphorated parachlorophenol. Synonym: p-chlorophenol. (05 Mar 2000) |
| P-congenitale | The P-wave pattern in the electrocardiogram seen in some cases of congenital heart disease, consisting of tall peaked P waves in leads I, II, aVF, and aVL (usually largest in lead II) with predominant positivity of diphasic waves in V1-2. See: spannungs-P. (05 Mar 2000) |