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Two independent bioassays are available which have examined the potential carcinogenicity of monomeric and polymeric methylene diphenyl diisocyanate (MDI) following long-term inhalation exposure in rats. These studies are not directly comparable, however, due to differences in design and conduct of the in-life phase, and differences in nomenclature used for(More)
1. A semi-synthetic diet, the semi-synthetic diet plus pectin, and a stock diet were fed to rats, and three metabolic functions of the caecal bacteria (reduction of amaranth, p-nitrobenzoic acid and nitrate) were measured in vitro. 2. No consistent differences were noted between diets for the reduction of amaranth and p-nitrobenzoic acid. 3. No consistent(More)
A comparison was made in six species of animal (rat, mouse, hamster, guinea-pig, marmoset and man) of five enzyme activities associated with the hindgut microflora. Marked differences were found in the caecal activities of azoreductase, beta-glucosidase, beta-glucuronidase, nitrate reductase and nitroreductase in the four rodents, with no one species(More)
The activities of four bacterial biotransformation enzymes (beta-glucosidase, beta-glucuronidase, nitrate reductase and nitroreductase) were measured in the caecal contents of conventional flora rats or germ-free rats contaminated with a mixed, human faecal flora and compared with activities present in a fresh human stool preparation. Both the conventional(More)
Peptides belonging to the FMRFamide family are widely distributed amongst invertebrates. We report here on the isolation of the FMRFamide neuropeptide AF2 (Lys-His-Glu-Tyr-Leu-Arg-Phe-NH2) from the parasitic nematode Haemonchus contortus. Immunocytochemical techniques showed that FMRFamide-like material was distributed in several regions of these organisms(More)
Subchronic 90-day feeding studies were conducted in male and female Fischer-344 (F-344) rats on highly refined white mineral oils and waxes representative of those used for food applications. The goal was to help clarify the mixed results found in other toxicity studies with laboratory animals. Seven white oils and 5 waxes were fed at dietary doses of(More)
The review will encompass the following points: A brief introduction to the role of the gut flora in the toxicology of ingested food components, contaminants, and additives, including known pathways of activation and detoxication of foreign compounds and the implication of the flora in enterohepatic circulation of xenobiotics. The advantages and(More)
Rats, mice, and hamsters were fed a fiber-free purified diet for 30 days and the activity of a number of cecal microbial enzymes was determined. Expressed per gram cecal content, azoreductase activity was greatest in preparations from the hamster and least from the mouse, and beta-glucosidase and beta-glucuronidase activities were least active from the rat.(More)
The endogenous formation of apparent total N-nitroso compounds (ATNC) has been investigated in germ-free (GF) and conventional (CV) microflora rats as a function of the drinking-water nitrate concentration. ATNC levels were below the 40 micrograms (N-NO)/kg detection limit in the blood, liver, kidney, spleen and small intestine of all CV and GF rats. For(More)
A fibre-free diet, or the same diet supplemented with 100 g cabbage or carrot cell-wall preparation/kg, was fed to rats for 28 days and the activities of a number of caecal microbial enzymes (azoreductase, aryl nitroreductase, beta-glucosidase, beta-glucuronidase, imidazole nitroreductase and nitrite reductase) were determined in vitro. The plant cell-wall(More)