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Biomedical subjects

R T Coutts

Publications and source records attributed to R T Coutts.

At least 163 records · Page 9Linked to original sources
PubMed1983

Selected ion mass spectrometric identification of chlorophenol residues in human urine.

A method is presented for the detection and confirmation of trace chlorophenol residues in environmental and biological samples by mass spectrometry with selected ion monitoring (SIM). Propionate and acetate ester derivatives of phenol, cresols, mono-, di-, tri-, and tetrachlorophenols, pentachlorophenol, as well as the internal standard 4,6-dibromo-o-cresol, were prepared directly in aqueous solution, using the appropriate anhydride reagent. The acetate or propionate esters were quantitatively extracted and then separated by gas-liquid chromatography using either an SP-1240DA or OV-101 packed column. Electron impact SIM was carried out by simultaneously monitoring up to 4 diagnostic fragment ions of each chlorinated phenol. The use of SIM eliminated background interference encountered using flame ionization or electron capture detectors, and allowed identification of chlorophenol residues in extracts of urine samples collected from individuals without known exposure to chlorophenols. Phenol concentrations as low as 1.0 pmol/mL urine gave peaks that were readily discernible by SIM.

Acetates↗
PubMed1982

Stereospecific metabolic reduction of ketones.

The stereospecificity of the metabolic reduction of arylalkylketones was investigated. The ketones, propiophenone (I), phenyl-acetone (III), and 1-phenyl-1,2-propanedione (V) were reduced in vitro and in vivo in rats and rabbits to the corresponding alcohols, 1-phenyl-1-propanol (II), 1-phenyl-2-propanol (IV), and 1-phenyl-1,2-propanediol (VIII), respectively. For the analysis, a capillary GLC method employing chiral derivatizing reagents for the resolution of these optically active alcohols was utilized. This study revealed that the metabolic reduction of each ketone produced the corresponding alcohol as a mixture of its enantiomers. With one exception, the mixtures obtained from all in vivo and in vitro reactions were shown to contain at least 70% of one isomer [S(-)-II, S(+)-IV, and erythro-VIII, respectively], with in vitro reduction showing the highest degree of stereospecificity (90-98%). The in vivo reduction of I by the rat was exceptional in that both optical isomers of II were recovered in equal proportions.

Alcohols↗
PubMed1982

Analysis of a monofluorinated analogue of amphetamine in brain tissue using gas chromatography with electron-capture detection.

1. Difficulties encountered in the analysis of the monofluorinated amphetamine, 2-amino-3-fluoro-1-phenylpropane (AFP), are discussed. 2. A novel assay procedure and its application to the analysis of AFP in the rat brain are described. The procedure involves pentafluorobenzoylation of AFP under aqueous conditions and quantitation by a gas chromatography equipped with a capillary column and an electron-capture detector.

Amphetamines↗
PubMed1982

Interaction of beta-carbolines with the benzodiazepine receptor. Structure-activity relationships of amide derivatives of beta-carboline and tetrahydro-beta-carboline.

1. The inhibition of specific 3H-flunitrazepam binding to rat cortical membrane preparations (benzodiazepine receptors) by a series of amide derivatives of beta-carboline and tetrahydro-beta-carboline related to the ethyl ester of beta-carboline 3-carboxylate (beta-CCE) was measured. 2. beta-Carboline amides which are unsaturated in the C ring of the beta-carboline nucleus were the most potent inhibitors of benzodiazepine receptor binding. 3. Increasing the length of the hydrocarbon moiety in the aliphatic amide side chain beyond two carbon atoms decreased potency.

Animals↗
PubMed1982

In vivo and in vitro o-methylation of 1-(3,4-dihydroxyphenyl)-2-(n-propyl-amino) propane - an intermediate in N-(N-propyl) amphetamine metabolism.

In vitro metabolism of 1-(3,4-dihydroxyphenyl)-2-(n-propylamino)-propane (Id) by rat liver cytosol in the presence of S-adenosyl-L-methyl-methionine produced almost quantitatively the corresponding 3-methoxy metabolite. 1-(4-Hydroxy-3-methoxyphenyl)-2-(n-propylamino) propane was also recovered from the urine of rats dosed with the catecholamine (Id).

Animals↗
PubMed1981

Interactions of beta-carbolines with the benzodiazepine receptor: structure-activity relationships.

The effects of a number of beta-carboline derivatives on [3H]flunitrazepam binding to the benzodiazepine binding site were investigated. The potency of beta-carbolines at the benzodiazepine binding site appeared to be determined largely by the aromaticity of the molecule. Norharmane-3-carboxylic acid ethyl ester was considerably more potent (IC50 10 nM) than its tetrahydro-beta-carboline analogue (IC50 6 microM). There is essentially no difference in potency between the (+)- and (--)-forms of the tetrahydro-beta-carboline-3-carboxylate analogues.

Animals↗
PubMed1981

The effects of cofactor and species differences on the in vitro metabolism of propiophenone and phenylacetone.

In vitro metabolism of the aromatic ketone propiophenone and its nonaromatic isomer phenylacetone was studied using fortified 12 000 X g supernatants of liver homogenates from rat and rabbit. Reduction to the corresponding alcohols was the major metabolic route observed, although aliphatic C-hydroxylation and alcohol dehydrogenation also occurred. Marked differences were observed in the amounts of carbonyl reduction of the substrates, which was dependent on the species as well as the cofactor employed. Using rat liver preparation, phenylacetone was reduced to 1-phenyl-2-propanol much more efficiently with an NADH-fortified system than when NADPH was used whereas in rabbit, extensive reduction occurred in the presence of either cofactor. Reduction of propiophenone to 1-phenyl-1-propanol by rat liver preparation was slightly greater in the presence of NADH than with NADPH; the converse was observed in rabbit. Aliphatic hydroxylation of propiophenone to 2-hydroxy-1-phenyl-1-propanone was also a significant metabolic pathway in both species, with NADPH being the more efficient cofactor, but C-1 hydroxylation of phenylacetone to 1-hydroxy-1-phenyl-2-propanone occurred only to a minor extent. Small amounts of 1-phenyl-1,2-propanedione, as well as both erythro and threo isomers of 1-phenyl-1,2-propanediol, were also identified as metabolites in both species. Similar metabolic studies were carried out on the alcohols 1-phenyl-1-propanol and 1-phenyl-2-propanol and again the nature and quantities of metabolites isolated showed both species and cofactor dependencies.

Acetone↗