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Laboratory and clinical reports about the pathogenesis of the carcinogenicity and allergenicity of chromium compounds published between 1985 and 2000 have been reviewed as a basis for consideration of the pathogenetic mechanisms involved. There is good evidence from the clinic and the laboratory that Cr[VI] is the ion responsible for most of the toxic(More)
1. The photochemical generation of excited states of oxygen in liver cell culture by the mild ilumination of culture medium containing riboflavin, results in stimulation of benzo[a]pyrene 3-mono-oxygenase, a cytochrome P-450-linked mono-oxygenase. 2. The same large increase in mono-oxygenase activity was found when medium containing riboflavin was(More)
In rat liver cell culture both benzanthracene and phenobarbitone induce the activity of benzypyrene hydrxylase while only phenobarbitone increases NADPH cytochrome c reductase activity. Benzpyrene hydroxylase but not NADPH cytochrome c reductase activity is dependent on the amino acid concentration of the culture medium in a similar manner to the regulation(More)
The "Holy Grail" of in vitro toxicology is to develop assay systems that mimic the in vivo situation and hence reduce the need for toxicity tests employing experimental animals. However a major problem to be overcome with cell culture models is the rapid loss of differentiated phenotype that markedly limits extrapolation of results to the whole animal (i.e.(More)
The commonly observed loss of liver specific phenotype regularly described in rat hepatocyte culture is typified by the loss of total cytochrome P450 (CYP) content and the altered abundance of CYP mRNAs. The current work shows that these changes are preceded by the induction of the mRNA encoding the transcription factor c-jun during the hepatocyte isolation(More)
The success of RNA interference (RNAi) in mammalian cells, mediated by siRNAs or shRNA-generating plasmids, is dependent, to an extent, upon transfection efficiency. This is a particular problem with primary cells, which are often difficult to transfect using cationic lipid vehicles. Effective RNAi in primary cells is thus best achieved with viral vectors,(More)
The drug metyrapone in the presence of glucocorticoid has been shown to induce the expression of rat hepatic cytochrome P-450 (CYP) 1A1 mRNA in vivo and in vitro through disruption of endogenous CYP1A1 regulator homeostasis and without either compound's binding to the aryl hydrocarbon receptor. Addition of metyrapone to human liver cancer cell cultures,(More)