Search PubMed⌕ Search

Biomedical subjects

N Gerber

Publications and source records attributed to N Gerber.

At least 127 records · Page 7Linked to original sources
PubMed1976

Separation of permethylated isomeric glucuronides by gas chromatography and analysis of the mass spectra.

Glucuronic acid conjugates of several foreign compounds (1- and 2-naphthols, 2-, 3-, and 4-hydroxybiphenyls, m- and p-hydroxyphenylphenylhydantoins) were produced in the isolated perfused rat liver and identified in the bile as the permethyl derivatives. Permethylated glucuronide isomers were easily separated by gas chromatography on SE-30 and OV-17 columns. The mass spectra of permethylated glucuronide isomers were very similar. Gas chromatography proved to be most useful for the separation and identification of isomeric glucuronides.

Animals↗
PubMed1976

Metabolism of 5-(p-toluyl)-5-ethylbarbituric acid and 5-(p-toluyl)-5-phenylhydantoin in the isolated perfused rat liver.

The primary route of metabolism of 5-(p-toluyl)-5-ethylbarbituric acid (TEBA) and 5-(p-toluyl)-5-phenylhydantoin (MPPH) in the isolated perfused rat liver is oxidation of the aromatic methyl group either to a primary alcohol which is then conjugated with glucuronic acid and excreted in the bile (MPPH only) or to the carboxylic acid which is excreted free in the bile (both TEBA and MPPH). All metabolites were identified by previously described permethylation and GC-MS techniques.

Animals↗
PubMed1976

Studies on the comparative pharmacology and selective toxicity of tricaine methanesulfonate: metabolism as a basis of the selective toxicity in poikilotherms.

Tricaine methanesulfonate, administered at a dose of 150 mg/kg i.p., produced a flaccid paralysis and loss of the righting reflex in a number of poikilothermic species including the frog. Leopard frogs (Rana pipiens) given 150 mg/kg i.p. regained the righting reflex at 113 +/- 28 (S.D.) minutes after injection. A similar dose administered i.p. to mice produced no apparent pharmacological response. The biological half-life (T1/2) of tricaine in frogs (R. pipiens) was about 70 minutes at temperatures of 23 and 37.5 degrees C; at 7 degrees C the T1/2 was 309 minutes. In contrast, in the mouse the drug was metabolized so rapidly that 5 minutes after i.p. administration of 5 mg of tricaine methanesulfonate (250 mg/kg) none of the unchanged drug could be recovered from the animal. It was, however, recovered quantitatively as Bratton-Marshall reacting metabolites, including m-aminobenzoic acid. Incubations of tricaine with serum from bullfrogs, mice and humans indicated that the drug was metabolized to m-aminobenzoic acid with an apparent Km of 3 X 10(-3) M for the reaction. The Vmax for incubations of the drug with bullfrog and human serum was 40 nmol/min/ml of serum, whereas in mouse serum it was 93 nmol/min/ml of serum. In vitro studies with liver homogenates showed that mouse liver metabolized tricaine 39 times more rapidly than frog liver. We conclude, therefore, that the liver is the major site of tricaine hydrolysis in mammals and that the selective toxicity of tricaine for poikilotherms is a consequence of their slower rate of hepatic biotransformation of tricaine.

Aminobenzoates↗
PubMed1976

Identification of glucuronide metabolites of d- and 1-methadone in bile from the isolated perfused rat liver.

Three hydroxylated metabolites of methadone, 2-ethyl-3-(dihydroxyphenyl)-5-methyl-3-phenylpyrroline (di-HO-EMDP), 2-ethyl-3-(hydroxy-methoxy-phenyl)-5-methyl-3-phenylpyrroline (HO-MeO-EMDP) and 2-ethyl-3-(hydroxy-phenyl)-5-methyl-3-phenylpyrroline (HO-EMDP) were excreted as O-glucuronide conjugates in bile from the isolated perfused rat liver following the addition of either d- or 1-methadone to the perfusate. These glucuronide metabolites were identified as intact molecules by combined gas chromatographic-mass spectrometric (GC-MS) analysis of their permethylated derivatives.

Animals↗
PubMed1975

Metabolism of methocarbamol (robaxin) in the isolated perfused rat liver and identification of glucuronides.

1. Permethylation and g.l.c.-mass spectrometric analysis of bile from an isolated rat liver perfusion to which methocarmol was added showed seven components not present in control bile: methocarbamol, glucuronides of methocarbamol and desmethyl-methocarbamol, and four glucuronides of hydroxylated methocarbamol metabolites. 2. An interesting rearrangement of a methyl group has been found in the mass spectrum of 3-(2-methoxyphenyloxy)-1,2-dimethoxypropane, the permethylation product from methocarbamol.

Animals↗
PubMed1975

Influence of pH on the contractor effect of convulsant barbiturate on frog lung.

Pentobarbial, thiopental and the convulsant 5-ethyl-5-(2-cyclohexylideneëthyl) barbituric acid (CHEB) were tested for contractor effect on the isolated lung of the fullfrog at pH 7.0 (7% CO2 and 20 mM HCO3-) and pH 8.4 (0.3% CO2 and 20mM HCO3-). CHEB was a potent contractor, thiopental a feeble contractor, and pentobarbital lacked contractor effect. The contractor potencies of both CHEB and thiopental were greater at the more acid pH. The potencies of formally charged agonists such as acetylcholine and K+ were not altered by the pH differences employed in these experiments. The pKa of CHEB was found to be 8.18 at 15 degrees C and 8.03 at 27 degrees C. Calculation of concentration-effect relationships of ionized and nonionized CHEB showed that only the nonionized CHEB was responsible for the contractor effect.

Acetylcholine↗