Glutathione content and glutathione -S-transferase activity in urinary bladder tumor tissues associated with schistosomiasis

GSH and GST activity were measured in eleven human bladder tumor and adjacent uninvolved specimens obtained from Egyptian patients with a history of schistosomal infection, undergoing cystectomy. The expression of GST[pi] was also measured using Western blotting analysis. GSH was higher in the tumor than in surrounding uninvolved tissue, though the difference was not significant. Total GST activity and GST[pi] expression were significantly higher [p < 0.05] in tumor tissues than in uninvolved tissues. There was a positive correlation between GST activity and GSH content in tumor tissues [r=0.64, p < 0.0005] and in surrounding uninvolved tissues [r = 0.72, p < 0.001]. A good correlation was also observed between total GST activity and GST[pi]expression in both tumor [r = 0.75, p < 0.05] and uninvolved tissues [r = 0.86, p<0.01]. To our knowledge, this is the first report of GST activity and GSH content in bladder cancer tissues associated with schistosomiasis. Our results suggest that one mechanism of resistance of this tumor to DNA interacting agents might be related to their inactivation by the GSH/GST system

Effect of intraperitoneal sublethal doses of dimethoate on rat hepatic gluconeogenesis

Male Wistar rats were injected with dimethoate [10 mg/0.5ml saline i.e. 5% LD[50]] intraperitonitally for 7 successive days. Treated animals suffered from a significant loss in body weight and liver weight as compared to control group. The gluconeogenic enzymes; phosphoenolpyruvate carboxykinase [PEPCK] and fructose 1, 6- bishosphatase [FBPase] were examined in liver. The activity of both enzymes decreased significantly in the treated group. PEPCK and FBPase activities were measured in vitro in the presence and absence of different concentrations of dimethoate. Addition of dimethoate to the reaction mixture resulted in a decrease in the activity of both enzymes. PEPCK activity was inhibited by 1mM dimethoate [28% inhibition] while FBPase activity showed a 30% inhibition by 0.5 mM dimethoate. Addition of 5 mM dimethoate caused 45% and 50% inhibition to PEPCK and FBPase, respectively. Lineweaver- Burk plot of PEPCK and FBPase activity at different substrate concentrations in the presence and absence of 2 mM dimethoate gave an uncompetitive type of inhibition

Inhibitation of gluconeogenic enzymes in rat liver after intraperitoneal sublethal doses of dimethoate

Male Wistar rats were injected with dimethoate intraperitoneally for 7 successive days. The treated animals suffered from a significant loss in the body weight and liver weight compared to the control group. Two gluconeogenic enzymes: phosphoenolpyruvate carboxykinase [PEPCK] and Fructose 1.6-bisphosphatase [FBP ase] were examined in liver. A significant decrease in activity of both enzymes was found in the treated rats. This inhibition was at a significant value of P<0.05 for FBP ase and P<0.001 for PEPCK

Changes in serum lipid profile and esterases of rats after sublethal daily doses of dimethoate

Male Wistar rats were injected by dimethoate [10 mg/0.5 ml] daily for 8 successive days. Controls received the same amount of saline. A group of 5 rats were anesthetized at 0, 2, 4, 6 and 8 days of injection. Blood was withdrawn from heart. Serum lipid components and 4 species of serum esterases were assayed for each group. A general decrease in the activities of serum esterases was observed. - A marked decrease also was observed in lipids profile during the 8 days course of experiment