Amino acid transport in established adult rat liver epithelial cell lines.

The capacities of Na+-dependent transport of alpha-aminoisobutyrate, glutamine and glutamate in four established and three transformed rat liver epithelial cell lines were found to be considerably higher than those of isolated and cultured hepatocytes. At least for transport systems A and G- this seemed to be due to elevated values of Vmax, whereas the values for Km were quite comparable to those of hepatocytes. In contrast to hepatocytes, however, no significant hormonal stimulation of amino acid uptake could be detected in the cell lines.

Activities of chlorinated ethane and ethylene compounds in the Salmonella/rat microsome mutagenesis and rat hepatocyte/DNA repair assays under vapor phase exposure conditions.

Three chlorinated ethane and ethylene solvent products were examined for their genotoxicity in the Salmonella/microsome mutagenesis and hepatocyte primary culture DNA repair assays using vapor phase exposures. The positive control in this study, monochloroethylene (vinyl chloride), induced reversion mutation of Salmonella tester strains TA100 and TA1535 with enhancement by an exogenous activation system and elicited unscheduled DNA synthesis in rat hepatocytes in culture. Exposures to 1,1,1-trichloroethane (methyl chloroform) or 1,1,2-trichloroethylene samples which contained stabilizers resulted in increased recovery of revertant colonies of Salmonella at concentrations causing greater than 96% cell killing.

A comparison of different nutrient media and supplementation with dexamethasone for mouse colon organ culture.

Several complex nutrient media were compared for their effectiveness in maintaining viable and functional mouse colon mucosa in organ culture. The order of superiority for preserving survival of normal tissues for 14 days was: Williams' Medium E greater than Morgan's 199 greater than CMRL-1066 greater than Waymouth's MB 752/l greater than Eagle's MEM greater than Trowell's T8. The 3H-thymidine labeling index was highest in colon explants maintained in Morgan's 199 greater than Williams' Medium E greater than Waymouth's MB 752/l greater than CMRL-1066 greater than Eagle's MEM.

Abnormalities in liver iron accumulation during N-2-fluorenylacetamide hepatocarcinogenesis that are dependent or independent of continued carcinogen action.

The characteristics of liver iron accumulation were studied during N-2-fluorenylacetamide (FAA)-induced hepatocarcinogenesis in rats. After injection of iron-dextran in control rats, hepatocytes accumulated stainable iron evenly throughout hepatic lobules. During the feeding of FAA, iron accumulation was reduced in the midzonal and centrilobular regions.

DNA content of hyperplastic and neoplastic acinar cell lesions in rat and human pancreas.

Pancreatic acinar cell hyperplastic lesions and neoplasms in rats and humans were studied for their nuclear DNA content by microspectrophotometry. Atypical hyperplastic acinar cell lesions induced in rats by azaserine displayed a wide range of DNA contents, 1.5-8C for those composed of acidophilic-type cells and 1.

Phenotypic Properties of Preneoplastic Rat Liver Lesions and Applications to Detection of Carcinogens and Tumor Promoters.

A variety of cellular lesions arise during liver carcinogenesis by chemicals in rats. The altered focus is a lesion of hepatocytes that occurs early in hepatocarcinogenesis and appears to give rise to both neoplastic nodules and carcinomas. Foci display numerous phenotypic abnormalities which together with nuclear abnormalities indicate that they are truly a new altered population.

Differential effects of ethanol and other inducers of drug metabolism on the two forms of hamster liver microsomal aniline hydroxylase.

The aniline hydroxylase activity of microsomes isolated from hamster liver can be differentiated kinetically into high affinity (low K(m), form I) and low affinity (high K(m), form II) forms. Microsomes isolated from uninduced animals contain slightly more form I activity. The activity of the low affinity form (form II) is preferentially enhanced by Aroclor or 3-methylcholanthrene treatment, while phenobarbital treatment increases the activity of both forms.

The formation of azoxymethane, a colon carcinogen, during the chemical oxidation of methylamine.

Simple chemical oxidation of methylamine in aqueous solution or in methanol leads to the formation of significant amounts of azoxymethane, a strong carcinogen in rodents. Methods, including high pressure liquid chromatography, differential pulse polarography and gas chromatography-mass spectrometry, used for the identification of the carcinogen, are described.

Alteration by phenobarbital of membrane-associated enzymes including gamma glutamyl transpeptidase in mouse liver neoplasms.

Administration of phenobarbital for 5 to 7.5 weeks to aged C3HfB/HeN mice with spontaneous liver tumors produced an enhancement of gamma glutamyl transpeptidase activity in the tumors and a decrease in glucose-6-phosphatase and adenosine triphosphatase activity. Discontinuation of phenobarbital feeding for 5.

The deficiency of cyclic AMP responsive G1 controls in cultured malignant liver epithelial cells.

Normal rat liver epithelial cells in culture were blocked outside the S phase by dibutyryl cyclic AMP while malignant rat liver epithelial cells were slowed in S phase. It is suggested that this lack of normal response to a growth inhibitory factor by malignant cells may underly their relatively autonomous growth behavior.