Post-initiation inhibition of MeIQx hepatocarcinogenesis in rats by cysteine.

Rats were administered cysteine at a dose of 100 mg/kg b.w. 5 times per week after 2-amino-3, 8-dimethylimidazo [4,5-f] quinoxaline (MeIQx) treatment.

High susceptibility of p53 knockout mice to esophageal and urinary bladder carcinogenesis induced by N, N-dibutylnitrosamine.

In human cancer, alterations in the p53 tumor suppressor gene are the most common genetic alterations. The aim of the present study was to detect sensitivity of the p53 (+/-) mice and their littermates p53 (+/+) mice to N, N-dibutylnitrosamine (DBN) carcinogenicity. In experiment 1, 6-7-week-old p53 (+/-) and p53 (+/+) mice were treated with 0, 0.

Promoting effects of monomethylarsonic acid, dimethylarsinic acid and trimethylarsine oxide on induction of rat liver preneoplastic glutathione S-transferase placental form positive foci: a possible reactive oxygen species mechanism.

Dimethylarsinic acid (DMA) is a major metabolite of inorganic arsenicals, which are epidemiologically significant chemicals in relation to liver cancer in mammals. The present study was conducted to determine the promoting effects of organic arsenicals related to DMA [monomethylarsonic acid (MMA) and trimethylarsine oxide (TMAO)] on rat liver carcinogenesis using a liver medium-term bioassay (the Ito test). Male, 10-week-old, F344 rats were given a single i.

Detailed low-dose study of 1,1-bis(p-chlorophenyl)-2,2,2- trichloroethane carcinogenesis suggests the possibility of a hormetic effect.

To obtain information on the effects of nongenotoxic carcinogens at low doses for human cancer risk assessment, the carcinogenic potential of the organochlorine insecticide, 1,1-bis(p-chlorophenyl)-2,2,2-trichloroethane (DDT), in the liver was assessed in F344 rats. In experiment 1, 240 male animals, 21 days old, were administered 0, 0.5, 1.

Food restriction inhibits the growth of intestinal polyps in multiple intestinal neoplasia mouse.

The effect of food restriction (FR) on spontaneous intestinal carcinogenesis in multiple intestinal neoplasia (Min) mice was examined. Thirty male Min mice were allotted to ad libitum feeding control and 20% FR groups from six weeks of age until the end of the 13-week experimental period. Although the total number of visible intestinal polyps in the FR group was not significantly different from the control group value, a significant decrease in large-sized polyps (>2 mm) and an increase in small-sized polyps (< or =2 mm) were observed in the distal small intestine.

Formation of 8-hydroxydeoxyguanosine and cell-cycle arrest in the rat liver via generation of oxidative stress by phenobarbital: association with expression profiles of p21(WAF1/Cip1), cyclin D1 and Ogg1.

To evaluate the risk of exposure to so-called non-genotoxic chemicals and elucidate mechanisms underlying their promoting activity on rat liver carcinogenesis the formation of 8-hydroxy-2'-deoxyguanosine (8-OHdG), cytochrome P-450 (P-450) and hydroxyl radicals induction, DNA repair and alteration to cellular proliferation and apoptosis in the rat liver were investigated during 2 weeks of phenobarbital (PB) administration at a dose of 0.05%. Significant increase of hydroxyl radical levels by day 4 of PB exposure accompanied the accumulation of 8-OHdG in the nucleus and P-450 isoenzymes CYP2B1/2 and CYP3A2 in the cytoplasm of hepatocytes.