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Biomedical subjects

J K Baker

Publications and source records attributed to J K Baker.

52 records · Page 3Linked to original sources
PubMed1982

Study of the metabolic conversion of imipramine and desipramine to N-nitrosodesipramine by bacteria using a nitrogen-selective GC analysis.

A GC method using dual nitrogen selective and flame ionization detectors was developed for the determination of N-nitrosodesipramine using N-butyryldesipramine as the internal standard. The precision of the method was found to be +/- 5.0% and the accuracy was +/- 4.9%. The method could be used to detect 10 ng/ml of N-nitrosodesipramine in bacterial cultures. When desipramine and sodium nitrite were incubated with aerobic or anaerobic bacteria, the nitrosamine level was found to be 10-300 times higher than the controls. When imipramine and potassium nitrate were incubated with a mixed anaerobic culture, the level of N-nitrosodesipramine was found to be 4.5 times higher than the control.

Aerobiosis↗
PubMed1982

4-hydroxyquinoline-3-carboxylic acids as inhibitors of cell respiration. 2. Quantitative structure-activity relationship of dehydrogenase enzyme and Ehrlich ascites tumor cell inhibitions.

Studies on dehydrogenase enzyme inhibition have been extended with the design, synthesis, and correlation analysis of 7-[(substituted-benzyl)oxy]-, 7-[(substituted-phenethyl)oxy]-, and 7([substituted-phenoxy)ethoxy]-4-hydroxyquinoline-3-carboxylic acids. Sixteen new congeners and the fifteen molecules previously synthesized have been tested against cytoplasmic malate dehydrogenase and lactate dehydrogenase, as well as against mitochondrial malate dehydrogenase. The lipophilic congeners show a clear specificity for inhibition of the mitochondrial enzyme. Correlation analysis of the data on the three enzymes allows a comparison of the binding sites in quantitative terms, while examination of the data on inhibition of ascites tumor cell respiration affords an indication of membrane transport. A newly developed high-pressure liquid chromatography based retention index is compared to the octanol-water pi constant as a model for hydrophobic interactions.

Animals↗
PubMed1981

Metabolism of imipramine by microorganisms.

The microbial metabolism of imipramine was studied using selected fungal organisms. The major microbial metabolites were isolated, and their structures were established by spectroscopic analyses (particularly 13C-NMR) and by comparison with authentic samples. The microbial metabolites identified included 2-hydroxyimipramine, 10-hydroxyimipramine, iminodibenzyl, imipramine-N-oxide, and desipramine; these metabolites also have been found in mammalian metabolism studies.

Biotransformation↗
PubMed1981

Metabolism of phencyclidine by microorganisms.

A number of microorganisms were screened for their ability to metabolize phencyclidine. Two microorganisms, Beauveria sulfurescens and Cunninghamella echinulata, produced hydroxylated metabolites, which were identified as 1-(1-phenylcyclohexyl)-4-hydroxypiperidine and 4-phenyl-4-piperidinocyclohexanol by high-pressure liquid chromatographic analysis.

Basidiomycota↗
PubMed1980

High-pressure liquid chromatographic identification of drugs used in management of arthritis.

A screening procedure was developed for the identification of drugs used in the clinical treatment of arthritis. Each glucocorticoid, nonsteroidal anti-inflammatory agent, or tranquilizer was characterized by its retention on a reversed-phase high-pressure liquid chromatographic column and by the ratio of the response of dual UV detectors (254 and 280 nm). Although the retention times of all 14 drugs examined were less than 4 min. each drug could be distinguished easily from the other drugs in the series.

Anti-Inflammatory Agents↗
PubMed1980

Steroid structure and function VII. remarkable estrogenicity of 3-hydroxy-9 beta-estra-1,3,5(10)-triene-11,17-dione.

Remarkably high estrogenic activity was observed for 3-hydroxy-9 beta-estra-1,3,5(10)-triene-11,17-dione despite its unusual bent conformation. The 9 alpha epimer of this compound has markedly less activity despite the fact that its overall shape is nearly identical to that of estrone. The potency of these compounds in enhancing uterine weight in Fischer rats and reducing ovarian weight in parabiosed rats was compared with that of estrone, and the structures were unambiguously identified by X-ray crystallographic study. The results underscore the importance of the phenolic ring A to estrogenic activity, and suggest a tolerance of the putative estrogenic receptor to flexibility in overall molecular shape.

Animals↗
PubMed1980

Estimation of high pressure liquid chromatographic retention indices of narcotic analgetics and related drugs.

A method for the prediction of the retention index of drugs on C18 reversed-phase columns was developed and then applied to a series of drugs that were structurally related to morphine and to a series related to fentanyl. The HPLC retention index (/) of the test compounds was estimated using the equation: / = 200 pi + /ref. where pi was the sum of the Hansch substituent constants for the compound, and /ref. was the index experimentally observed for the reference compound of the series. It was also found that the observed index could be used to assign the stereochemistry of the fentanyl analogues.

Analgesics, Opioid↗
PubMed1979

Relationship of nonspecific antiarrhythmic and negative inotropic activity with physicochemical parameters of propranolol analogues.

In an attempt to separate the nonspecific antiarrhythmic activity of propranolol from its negative inotropic effects, analogues containing hydrophilic and lipophilic substituents on the nitrogen and on the naphthyl ring were prepared and tested in an isolated tissue preparation. Though it had been predicted that analogues containing a very hydrophilic group on the nitrogen would have the highest antiarrhythmic/negative inotropic effect ratio, it was found that both effects increased identically when the lipophilicity of either the nitrogen or ring substituent was increased.

Animals↗
PubMed1979

Correlation of biological activity and high-pressure liquid chromatographic retention index for a series of propranolol, barbiturate, and anthranilic acid analogues.

The antiarrhythmic activity of propranolol analogues, the inotropic activity of propranolol analogues, the anti-inflammatory activity of anthranilic acids, the hypnotic activity of barbiturates, and the inhibition of cell division by barbiturates were correlated with either octanol--water partition coefficients or with high-pressure liquid chromatographic retention indices. The retention index, which was a scale based on the relative retention of the drug and a series of C3--C23 2-ketoalkanes, was found to give higher correlations with biological activity than was found between octanol--water partition coefficients and biological activity. Only in the case of the anthranilic acids was the retention index found to give the lower correlation.

Animals↗
PubMed1978

Characteristics of the TEA detector in use with high pressure liquid chromatography.

It was found that the response of the TEA detector was highly dependent on the operating temperature of the furnace and on the flow rate of gas that is used to purge the furnace. It was also found that the response of the detector was very highly dependent on the volatility of the nitroso compound and the optimum operating conditions were also very different for low and high volatility compounds. When samples containing equal quantities of NDMA, NPYR, NPRO and NPIC were chromatographed at low furnace temperatures, only the peaks for NPRO and NPIC (low volatility) were observed. When a high furnace temperature was used, only NDMA and NPYR (high volatility) were routinely observed. At intermediate temperatures, all four compounds could usually be observed. Under optimum conditions, the sensitivity was 3 microgram/ml for NPRO and 5 microgram/ml for NPIC.

Chromatography, High Pressure Liquid↗