The mutagenicity of SRM 1649 and 1650 was tested in the presence of rat liver S9 mix which was induced by polychlorinated biphenyl (PCB) or by the combination of phenobarbital and 5,6-benzoflavone. The S9 mix induced by PCB activated benzo[a]pyrene strongly. The S9 mix induced by phenobarbital-5,6-benzoflavone activated the complex mixtures to approximately the same extent as that induced by PCB. This finding indicates that phenobarbital-5,6-benzoflavone instead of PCB may be suitable as an inducer under some conditions. The preincubation procedure for the mutagenicity test was performed by preincubating the test compound, S9 mix and bacteria for 20 min in a water bath. This procedure was as effective as the plate incorporation test.

Air Pollutants↗

PubMedDate not supplied

Reversibility of organic anion-induced cholestasis: association with compensatory hypersecretion of biliary phospholipid and protein in the dog.

The effect of a concomitant infusion of organic anions, structurally related phthaleins, on bile flow was studied in anaesthetized dogs. A combination of rose bengal and sulfobromophthalein was found to uniquely and synergistically produce an acute, reversible form of intrahepatic cholestasis (< 10% of control level). This phenomenon was not observed with the administration of those individual organic anions at concentrations previously associated with the induction of intrahepatic cholestasis. The infusion of either a micelle forming bile salt, sodium taurocholate, or a non-micelle forming bile salt, sodium dehydrocholate, rapidly reversed the intrahepatic cholestasis (within 20 min after bile salt infusion). During the choleretic phase immediately following the bile salt infusion, a transient but marked hypersecretion, a disproportionately increased output in relation to that of bile acids, of biliary phospholipid (176% of control level by taurocholate and 138% of control level by dehydrocholate), and an even more striking amount of biliary protein hypersecretion were observed (392% of control level by taurocholate and 357% of control level by dehydrocholate). Although the significance of these new post-cholestatic observations requires clarification, it is suggested that the intrahepatic cholestasis induced by organic anions reflects a reversible defect in the mechanism(s) involved in transcellular transport.

Animals↗

PubMedDate not supplied

An estimation of human bile metastability: clinical application of a sensitive cholesterol crystal growth assay.

The formation of cholesterol monohydrate crystal initiates cholesterol gallstone formation. The nucleation time (NT), a light microscopy method, is used currently to estimate human bile metastability. Recently, a cholesterol crystal growth (CCG) assay utilizing photometric turbidity to quantitate cholesterol crystallization was developed using model bile systems. The object of this study was to determine whether this novel CCG assay was applicable to the quantitative assessment of native human bile metastability. Human gall-bladder bile samples were collected from patients undergoing cholecystectomy. There were five patients with cholesterol gallstone and five stone-free patients. A significant correlation between the onset time measured by the CCG assay and the NT observed by light microscopy was found in our modified assay condition where interference by bilirubin was negligible (P < 0.01). Also, the growth rate measured by the CCG assay significantly correlated with the NT (P < 0.05). These results indicate that the CCG assay is applicable to quantitative assessment of human bile metastability reflected by cholesterol crystal nucleation and that the cholesterol crystal growth is also conveniently estimated by this method.

Bile↗