A comparison of the lung adenoma response in strain A/J mice after intraperitoneal and oral administration of carcinogens.

This study was undertaken to compare the ability of a series of compounds from different chemical classes to induce lung tumors in strain A/J mice after either ip or po administration. 3-Methylcholanthrene, benzo(a)pyrene, urethan, diethylnitrosamine, ethylnitrosourea, and dimethylhydrazine induced a significant (p less than 0.05; t test) increase in the lung tumor response when given both ip and po.

Carcinogen induced unscheduled DNA synthesis in mouse hepatocytes.

Mouse primary liver cell cultures were examined for evidence of unscheduled DNA synthesis (UDS) following treatment with the carcinogens; dimethylnitrosamine (DMNA), diethylnitrosamine (DENA), 2-acetylaminofluorene (2-AAF), N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), benzo(a)pyrene (BP), dimethylbenzanthracene (DMBA), 1,1,-bis(p-chlorophenyl)-2,2,2-trichloroethane (DDT), safrole, diethylstilbestrol (DES), aflatoxin B1 (AFB1), and dieldrin and the noncarcinogens; dimethylformamide (DMF), fluorene, and pyrene. Mouse hepatocyte cultures were simultaneously treated with three concentrations of each compound and 3H-thymidine. After 24 hrs, cells were fixed and processed for autoradiography.

Kinetics of DNA repair synthesis induced by bleomycin and N-methyl-N-nitrosourea in isolated rat liver nuclei.

Purified rat liver nuclei were incubated in the presence of a labeled deoxyribonucleoside triphosphate and bleomycin (an antitumor agent) or N-methyl-N-nitrosourea (MNU, a direct-acting carcinogen) to compare their abilities to induce DNA repair synthesis. It was found that bleomycin induced the incorporation of [3H]dTMP and, to a lesser extent, [3H]dCMP and [3H]dAMP, whereas MNU induced incorporation of [3H]dAMP exclusively. The bleomycin-induced DNA repair was linear with time, whereas the MNU-induced repair was more complex, requiring an induction period and lasting only 90 minutes.

Morphologic and functional studies of mouse hepatocytes in primary culture.

Mouse liver cells in primary culture were evaluated by high-resolution light microscopy (HRLM) and transmission electron microscopy (TEM). Cells after 2 hours of culture in L-15 medium supplemented with 10% fetal bovine serum were spherical in shape, and were either individual or in small clusters of up to ten cells. Following 1 day in culture, hepatocytes were flattened and usually found in groups.

In vitro transformation of rat esophageal epithelial cells with N-nitrosobenzylmethylamine.

Using an explant/cell culture system, rat esophageal epithelial cells were transformed in vitro by exposure to N-nitroso-N-benzyl-N-methylamine (BMNA). Twelve esophageal explant cultures per group were exposed twice (at days 1 and 7) to 0.0, 2.

Mouse liver cell culture. II. Primary culture.

Mouse hepatocytes in primary culture were characterized. Hepatocytes were isolated by the two-step hepatic portal vein perfusion method described previously. An optimal cell attachment of 43% was noted after 2 h incubation in 10% fetal bovine serum.

Mouse liver cell culture. I. Hepatocyte isolation.

A method for isolation of mouse liver cells by a two-step perfusion with calcium and magnesium-free Hanks' salt solution followed by a medium containing collagenase is described. Several variations of the commonly used procedure for rat liver cell isolation were quantitatively compared with respect to cell yield and viability. The optimal isolation technique involved perfusion through the hepatic portal vein and routinely produced an average of 2.

Biology of hepatocellular neoplasia in the mouse. III. Electron microscopy of safrole-induced hepatocellular adenomas and hepatocellular carcinomas.

A systematic, ultrastructural analysis wsa performed on safrole-induced hepatocellular adenomas and hepatocellular carcinoma(s) (HPC) in BALB/c mice. Adenomas were heterogeneous in cell composition containing dark-staining basophilic cells, pale-staining acidophilic cells, clear cells, and lipid-laden cells. Darkly staining cells resembled fetal hepatocytes.

Biology of hepatocellular neoplasia in the mouse. II. Sequential enzyme histochemical analysis of BALB/c mouse liver during safrole-induced carcinogenesis.

Sequential alterations in enzyme histochemical profiles and reaction of hepatocytes to rapid iron overload were examined in male BALB/c mice during chronic, safrole exposure. At 24 weeks after initiation of safrole treatment, foci of enzyme-altered hepatocytes were noted. These foci were composed of cells showing a decrease in reactivity for glucose-6-phosphatase (Glc-6-Pase) and succinate dehydrogenase (SDH) and an increase for gamma-glutamyl transpeptidase (gamma-Glu-T).

Biology of hepatocellular neoplasia in the mouse. I. Histogenesis of safrole-induced hepatocellular carcinoma.

A sequential, histologic analysis of the livers of male BALB/c mice chronically fed the hepatocarcinogen safrole (4,000 ppm) was performed at 2, 4, 8, 16, 24, 36, 52, and 75 weeks. The transplantability of selected lesions to syngeneic hosts was also assessed. Histopathologic liver alterations at 2, 4, 8, and 16 weeks induced hypertrophy of centrolobular hepatocytes, oval cell proliferation, fatty change in periportal hepatocytes, including basophilic, acidophilic, and clear cell, were noted.

Gamma glutamyl transpeptidase in safrole-induced, presumptive premalignant mouse hepatocytes.

A histochemical procedure was used to determine the presence of gamma-glutamyl transpeptidase (GGT) in the livers of control, regenerating and carcinogen-treated mice. Young Balb/c mice were fed safrole, a naturally occurring hepatocarcinogen (0.4% w/w), for one year.

Iron negative foci and nodules in safrole-exposed mouse liver made siderotic by iron-dextran injection.

A procedure for the production of mouse hepatic siderosis is described which results in extensive iron deposition in all lobular zones. Mice exposed to safrole for 24 weeks displayed basophilic and acidophilic foci which did not accumulate iron. 36 weeks of dietary safrole exposure resulted in nodular lesions comprised of basophilic and hyalinized cells.

Biochemical and ultrastructural changes in teleost liver following subacute exposure to PCB.

The response of the channel catfish liver to subacute exposure of polychlorinated biphenyls was evaluated using electron microscopic and biochemical techniques. After 21 days, treated fish displayed elevated microsomal enzyme activities. Morphologically, the liver produced several patterns of alteration involving the endoplasmic reticulum (ER).

Comparison of acute response to polychlorinated biphenyl in liver of rat and channel catfish: a biochemical and morphological study.

The acute response of liver of channel catfish and rat to polychlorinated biphenyl was compared on a structural and functional basis. Both the rat and the fish had elevated microsomal enzyme activities. However, in the rat the response was quantitatively greater in all respects.