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Biomedical subjects

P S Steyn

Publications and source records attributed to P S Steyn.

At least 19 recordsLinked to original sources
PubMed1989

Influence of ochratoxin B on the ochratoxin A inhibition of phenylalanyl-tRNA formation in vitro and protein synthesis in hepatoma tissue culture cells.

Ochratoxin B (OTB), the dechloro-analogue of ochratoxin A (OTA), was studied separately and in combination with OTA on the aminoacylation of phenylalanine tRNA (tRNAPhe) catalysed by mice liver phenylalanyl-tRNA synthetase. OTB was neither a significant inhibitor of the reaction nor an antagonist of OTA. OTB was also assayed for its possible antagonistic effect on the in vivo protein synthesis inhibition caused by OTA in hepatoma tissue culture cells. No prevention of OTA inhibition could be found for OTB. It rather showed a slight additional inhibitory activity when mixed (100-180 microM) with low concentrations of OTA (40-60 microM). In conclusion, these results are not in favor of an antagonistic effect of OTB with respect to OTA action, at least on the level of cellular protein synthesis.

Animals↗
PubMed1987

Smodingium dermatitis.

Smodingium argutum is the plant most commonly responsible for causing acute allergic contact dermatitis in South Africa. When an outbreak of Smodingium dermatitis occurred in a local school the allergenic principle present in this plant was chemically isolated and identified, and its allergenic property proved in the clinic by patch testing. The value of using an extract of fresh Smodingium leaves in lieu of fresh leaves themselves was confirmed, but freeze-dried material was found to be unsuitable for patch-test purposes.

Acute Disease↗
PubMed1979

Screening methods for the detection of thirteen common mycotoxins.

A study of screening methods for thirteen mycotoxins showed that they can be separated as neutral and acidic metabolites. RF values were determined in several solvent systems. The reactions of the mycotoxins with well known spray reagents were investigated, and their detection limits were established. A general procedure for the extraction of mycotoxins from contaminated samples is described.

Chromatography, Thin Layer↗
PubMed1977

Some newly discovered mycotoxins.

The discovery of the aflatoxins in 1960 has taken place in the present era of the intense awareness of the importance of environmental contaminants. It has dramatically influenced subsequent fungal research with the resulting rapid increase in the number of publications describing mycological, chemical, toxicological and epidemiological aspects of mycotoxins. In this contribution results will be discussed which were published only subsequent to 1970. In this period the importance of several new classes of mycotoxins was realized, e.g. the toxic cytochalasins and the tremorgens. The potential role of highly oxygenated metabolites in mycotoxicosis was emphasized by the establishment of secalonic acids A and D. emodin, moniliformin, altenuisiol alternariol and austdiol as toxins. The structure of viridicatumtoxin, C30H31NO11, a metabolite produced by Penicillium viridicatum will be described. It is a novel compound, structurally related to the tetracyclines. The characterization of several mycotoxins from other toxigenic fungi will be reported.

Cytochalasins↗
PubMedDate not supplied

Quantum-chemical studies of aflatoxin B1, sterigmatocystin and versicolorin A, and a comparison with their mutagenic activity.

The INDO atomic charges q and Wiberg bond indices p (in electrons) were calculated for aflatoxin B1, sterigmatocystin and versicolorin A. The C-2-C-3 bond in these compounds has the same bond order and is predicted to be the most reactive towards epoxidation. The electronic effects do not explain the observed differences in mutagenicity and toxicity.

Aflatoxin B1↗