In order to investigate the mechanisms of the anticarcinogenic effect of Chinese tea on the development of esophageal tumors in rats induced by N-nitrosomethylbenzylamine, the alkylation of DNA in various organs was s...In order to investigate the mechanisms of the anticarcinogenic effect of Chinese tea on the development of esophageal tumors in rats induced by N-nitrosomethylbenzylamine, the alkylation of DNA in various organs was studied in rats treated with 2 varieties of Chinese tea, i.e. Fujian Oolong tea and Jasmine tea. Male Wistar rats were given a single i.v. injection of N-nitroso-[methyl-14C]-benzylamine (2.5 mg/kg.body wt) after having been provided tea in drinking water and by gavage for 2-3 weeks. Control rats were provided with tap water. Three to four hours after administration of the Af-nitroso compound, the methylation of purine bases in the DNA isolated from various organs was measured by high performance liquid chromatography and liquid scintillation counting. In the tea-drinking rats, there was an appreciable reduction of O6-methylguanine formation in the esophageal DNA as well as the ratio of O6-metylguanine to N7-methylguanine, as compared to the control rats. No O6-methylguanine was detected in lung or liver DNA.展开更多
In this paper, we study a nonautonomous Lotka-Volterra competitive system with infnite delay and feedback controls. By means of a suitable Lyapunov functional, we establish sufcient conditions which guarantee the glob...In this paper, we study a nonautonomous Lotka-Volterra competitive system with infnite delay and feedback controls. By means of a suitable Lyapunov functional, we establish sufcient conditions which guarantee the global asymptotic stability of the system.展开更多
文摘In order to investigate the mechanisms of the anticarcinogenic effect of Chinese tea on the development of esophageal tumors in rats induced by N-nitrosomethylbenzylamine, the alkylation of DNA in various organs was studied in rats treated with 2 varieties of Chinese tea, i.e. Fujian Oolong tea and Jasmine tea. Male Wistar rats were given a single i.v. injection of N-nitroso-[methyl-14C]-benzylamine (2.5 mg/kg.body wt) after having been provided tea in drinking water and by gavage for 2-3 weeks. Control rats were provided with tap water. Three to four hours after administration of the Af-nitroso compound, the methylation of purine bases in the DNA isolated from various organs was measured by high performance liquid chromatography and liquid scintillation counting. In the tea-drinking rats, there was an appreciable reduction of O6-methylguanine formation in the esophageal DNA as well as the ratio of O6-metylguanine to N7-methylguanine, as compared to the control rats. No O6-methylguanine was detected in lung or liver DNA.
基金Supported by the Foundation of Fujian Education Bureau(No.JA12373)
文摘In this paper, we study a nonautonomous Lotka-Volterra competitive system with infnite delay and feedback controls. By means of a suitable Lyapunov functional, we establish sufcient conditions which guarantee the global asymptotic stability of the system.
