The effects of a colchicine-induced M-phase block of regeneration after partial hepatectomy on early-stage liver carcinogenesis were studied in rats. When administered 1 or 3 days after N-diethylnitrosamine initiation and partial hepatectomy, colchicine increased the mitotic index of regenerating hepatocytes at days 4-6 without evidence of liver cell necrosis. When the protocol was combined wit...

In order to elucidate the mechanism underlying enhancement by ethanol of N-nitrosodiethylamine (DEN)- and N-nitrosomethylbenzylamine (NMBA)-induced esophageal tumorigenesis in rats, hepatic levels of cytochrome P-450 (CYP) enzymes, mutagenic activation of several N-nitrosamines and three kinds of UDP-glucuronyltransferase (UDPGT) activities were assayed in F344 rats. Immunoblot analyses of micr...

The development of hepatocellular tumors was investigated with histological, histochemical, and morphometrical methods in male Sprague-Dawley rats continuously administered N-nitrosodiethylamine (DEN) or N-nitrosomorpholine (NNM) in the drinking water at low doses (0.5 mg DEN/100 ml; 1 mg NNM/100 ml). Groups of control, DEN-, and NNM-treated rats were investigated at 5-week intervals. Similar r...

The present study is designed to investigate the preventive effects of actinobacterial extract on colon carcinogenesis in NDEA induced mice tumor. Twenty four mice were divided into four groups of six animals each. Animals (Group I) proceed as the control without any treatment. Animals (Group II) were intraperitonially injected with Nnitrosodiethylamine at three doses at an interval for ten day...

A Weibull analysis is presented of the dose and time relationships for the effects on 4080 inbred rats of chronic ingestion in the drinking water of 16 different doses of N-nitrosodimethylamine (NDMA) or N-nitrosodiethylamine (NDEA). The sites chiefly affected were the liver (by both agents) and the esophagus (by NDEA only). Since the experiment continued on into extreme old age, effects became...

Alcohol consumption is frequently associated with various cancers and the enhancement of the metabolic activation of carcinogens has been proposed as a mechanism underlying this relationship. The ethanol-induced enhancement of N-nitrosodiethylamine (DEN)-mediated carcinogenesis can be attributed to an increase in hepatic activity. However, the mechanism of elevation of N-nitrosomethylbenzylamin...