Biomedical subjects
Publications and source records attributed to R H Thomson.
Angiosperms, fungi (including lichens), and bacteria are the main sources of natural quinones. Small numbers are present in algae, ferns, conifers, sponges, echinoderms, other marine animals, and arthropods. In angiosperms quinones have some chemotaxonomic value at the genus and family level but more surveys are required.
5,8-Dihydroxyflavone (primetin) has been shown to be the sensitizer in Primula mistassinica Michaux and probably the source of allergic contact dermatitis in four milkers. Its sensitizing properties as determined in guinea-pigs, are strong. As far as is known this is the first experimental demonstration of the sensitizing potency of a flavone. Presumably the flavone, with its uncommon 5,8-arrangement of hydroxy groups, is oxidized in the skin to the corresponding quinone (primetinquinone). Quinone was prepared from primetin and used for experimental sensitization of guinea-pigs. It also revealed strong sensitizing properties. Cross-reactions were obtained not only with the synthetic quinone in the flavone-sensitive animals but also with primetin in primetinquinone-sensitive guinea-pigs. Preliminary sensitization tests with other flavones have demonstrated that the whole group of flavonoid components should be taken into consideration as potential sensitizers.
The survival of Salmonella typhimurium was investigated in acidogenic, anaerobically fermented pig wastes and in synthetic media, each containing volatile fatty acids (VFA). Salm. typhimurium survived at pH 6.8, but not at pH 4.0, when incubated at 37 degrees C for 24 h in either fermented or synthetic medium containing VFA. The minimum inhibiting concentration of VFA for Salm. typhimurium after 48 h incubation at 30 degrees C at pH 4.0 was 0.03 mol/l and for Escherichia coli it was 0.09 mol/l. Fermented pig wastes in a digester, maintained at pH 5.9, were inoculated with Salm. typhimurium and then incubated at 37 degrees C for 24 h. The pH was adjusted to either 4.0 or 5.0 and after a further 48 h at 30 degrees C, Salm. typhimurium survived at pH 5.0 but not at pH 4.0. It was concluded that pH is critical in determining the survival of this organism in acidogenic anaerobically fermented pig waste.
Gadusol, C8H12O6, has been isolated from roes of the cod (Gadus morhua L.), i.e., ovaries that contain ripe eggs just before spawning. The concentration is about 4 g/kg dry wt. It has been identified as 1,4,5-trihydroxy-5-hydroxymethyl-2-methoxycyclo-hex-1-en-3-one and this structure was confirmed by synthesis of the anhydro tetra-acetate derivative from methyl 3,5-diacetoxy-4-methoxybenzoate. Concentrations of gadusol in the roes of other marine teleost fish examined are of the same order as in cod roes. Gadusol has some properties similar to ascorbic acid and both compounds, after oxidation, react with 2,4-dinitrophenylhydrazine in the commonly-used assay procedure for ascorbic acid. Specific assays showed that the concentrations of gadusol in the roes of marine fish are severalfold greater than those of ascorbic acid. Gadusol is structurally related to the mycosporines previously reported from a number of different organisms.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
A pellicle-forming yeast, identified as Candida ingens, was found to grow on substrates derived from the anerobic fermentation of monogastric animal wastes. The organism used volatile fatty acids C2 to C6 and ammonia nitrogen. It had a preferential uptake of the acids in increasing order of molecular weight, removing 90% of the total titratable volatile acid. The nonwrinkled pellicle had a doubling time of 3.2 h, and the doubling time of the wrinkled pellicle was 4.2 h. Proximate amino acid and nucleic acid analyses suggested that the organism might be acceptable as a source of single cell protein. Its vitamin B group content compared favorably with that of other yeasts. It contained 6% calcium and 7% phosphorus. It could be useful in removing these minerals from effluents as well as in providing them as nutrients in livestock rations.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.