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Biomedical subjects

S Safe

Publications and source records attributed to S Safe.

At least 289 records · Page 16Linked to original sources
PubMed1976

In vitro binding of sterols by extracts from Mucor rouxii cells grown under different environmental conditions.

Aqueous cell wall and cytoplasm extracts from Mucor rouxii cells grown under acrobic and anaerobic (oxygen-limiting) conditions were obtained. Both of the extracts from the anaerobic and aerobic cells solubilized lanosterol and ergosterol but not to the same extent; ergosterol was complexed about 2-3 times greater than the same concentration of lanosterol. It was also apparent that the relative bindingcapacities of the cell extracts were dependent on the cell growth environment. Two additional fractions were obtained from each extract by (a) methanol precipitation and (b) refluxing in 2% aqueous potassium hydroxide solution followed by methanol precipitation. The binding activities of these precipitates and the corresponding precipitates from yeast extract were compared and the results indicated a range of binding activites which depended on both the extract and the sterol. The data suggested that the in vitro sterol binding of M. rouxii extracts was not due to one particular macromolecule but that a number of compounds were involved in this complexation process.

Aerobiosis↗
PubMed1976

The metabolism of higher chlorinated benzene isomers.

The metabolism of the isomeric tri- and tetrachlorobenzene isomers, penta- and hexachlorobenzene was investigated in the rabbit. The major urinary metabolites of the isomeric tri- and tetrachlorobenzenes were identified as the corresponding tri- and tetrachlorophenols whose structures were confirmed by chromatographic analyses. The genesis of the formation of metabolites is discussed in terms of their possible arene oxide intermediates in which the NIH shift of a chlorine atom is observed in the oxidation of many of the isomers. Pentachlorobenzene is metabolized to give both pentachlorophenol and a dechlorination-hydroxylation product which was identified as 2,3,4,5-tetrachlorophenol. The hexachlorobenzene substrate did not give any phenolic metabolites.

Animals↗
PubMed1976

Lysosomal membrane labilization by DDT, DDE and polychlorinated biphenyls (PCB).

Incubation of the ubiquitous pollutants, polychlorinated biphenyls (PCB), DDT and DDE with rat liver lysosomes shows that these lipophillic substrates are highly active labilizers of lysosomal membranes. The release of acid phosphatase was used as a marker enzyme and at high PCB, DDT and DDE concentrations (2X10(-3)M) the lytic activity was similar to that of the detergent Triton X-100; at lower concentrations most of the commercial PCB samples, DDT and DDE still retain considerably lytic activity.

Animals↗
PubMed1976

The in vitro metabolism, macromolecular binding and bacterial mutagenicity of 4-chloribiphenyl, a model PCB substrate.

The in vitro metabolism of 4-chlorobiphenyl, a model polychlorinated biphenyl (PCB) substrate, proceeds via an arene oxide intermediate to give the observed in vivo hydroxylated metabolites. The rabbit liver microsomal fraction mediates binding between the PCB and the endogenous microsomal protein and RNA and the major part of the PCB was bound to the light 3S-10S RNA fraction. The lower chlorinated 4-chlorobiphenyl isomer was highly mutagenic to the Salmonella typhimurium strain TA1538 (sensitive to frameshift mutagens) whereas higher chlorinated PCB were only weakly mutagenic.

Animals↗
PubMed1975

The effect of growth environment on the chloroform-methanol and alkali-extractable cell wall and cytoplasm lipid levels of Mucor rouxii.

The distribution of chloroform-methanol and alkali-extractable lipids in the cell walls of aerobically grown filamentous cells from Mucor rouxii has been determined. The results have been compared with the corresponding lipid composition of yeast-like cells from M. rouxii, which can be produced in two ways: by growth under anaerobic conditions and by aerobic growth in the presence of 0.22% phenethyl alcohol (PEA). It was observed that in most cases the crude cytoplasmic fraction contained higher levels of several lipids (i.e., squalene, sterols, triterpenes, and fatty acids) than did the corresponding cell walls. The cell walls did, however, contain both "free" (chloroform-methanol extractable) and "bound" (alkali extractable) lipids although the relative amounts were markedly dependent on the cell growth environment. The aerobically grown filamentous cell walls contained higher levels of squalene, sterols, triterpenes, and fatty acids than did aerobically grown yeast-like PEA-induced cell walls and there was also considerable variation in the "free"/"bound" ratios of the various lipid components. The lipid levels in both the cell walls and cytoplasm of the anaerobically grown cells were considerably lower than those of the cells grown under aerobic conditions. In addition, the differences in the growth environment were also reflected in the compositions of the individual lipid fractions from both the cell wall and the cytoplasm fraction.

Aerobiosis↗
PubMed1975

The metabolism of 4'chloro-4-biphenylol in the rat.

4'Chloro-4-biphenylol, the major metabolite of 4-chlorobiphenyl in the rat, was given intraperitoneally to rats, and the urine and feces were examined for possible metabolic degradation products. The structure of the major urinary metabolite was elucidated by mass and nuclear magnetic resonance spectroscopy and shown to be 4'-chloro-3,4-biphenyldiol. Two chloromethoxbiphenylols (m-4) were also identified in the urine extracts but they could not be separated by chromatographic procedures. Demethylation of the mixture gave 4'-chloro-3,4-biphenyldiol as the sole product, thus indicating that the two components of the mixture were 4'-chloro-3-methoxy-4-biphenylol and 4'-chloro-4-methoxy-3-biphenyldiol. No 4'-chloro-4-biphenylol metabolites were isolated in the fecal extracts, and mass spectrometric analysis of the crude urine and feces extracts did not reveal any chlorine-containing degradation products that could be derived by oxidative fission of the biphenyl nucleus.

Animals↗
PubMed1975

The metabolism of 4-chlorobiphenyl in the pig.

1-Chlorobiphenyl was administered retrocarotidly in a saline oil emulsion to anesthetized pigs. The urine obtained from the pigs 2 h after injection of the 4-chlorobiphenyl was analyzed for metabolites. Mass spectrometric analysis indicated the presence of a monohydroxylated species (M+ 204) and a dihydroxylated compound (M+ 220) and these were identified as 4'-chloro-4-biphenylol and 4'-chloro-3,4-biphenyldiol, respectively. Examination of the urine extracts from pigs 0.5, 1, and 2 h after administration of the 4-chlorobiphenyl indicated an increase in both urinary metabolites with time, however, neither compound was detected in the bile. Blood and organ samples were examined also for metabolites and the results clearly showed the presence of 4'-chloro-4-biphenylol in the blood, kidney, and liver and absence in the lung, brain, and heart. The diol was not observed in any of these samples.

Animals↗