AIM: To explore the effect of low concentration of N-methyl-N-nitro-N-nitroguanidine (MNNG) on p38MAPK, and the function of glutathione (GSH) on p38MAPK. METHODS: Western blotting was applied to detect the p38MAPK phosphorylation in MNNG treatment group and control group. To study the effect of GSH on MNNG-regulated p38MAPK activity, the intracellular GSH level was reduced by pretreatment of L-buthionine-S, R-sulfoximine (BSO). Assuming the absorbance of band in control group as 1.0, the relative P/T values of the treatment groups were calculated, with the “P” served as absorbance values of phospho-p38MAPK and the “T” as absorbance values of total p38MAPK. RESULTS: In BSO pretreated groups,the relative P/T in samples treated with MNNG for 2.5 h was 0.84, and became 2.19 with 3 h more incubation in the fresh medium. CONCLUSION: GSH deletion increases the activity of p38MAPK in MNNG treatment.

AIM: To identify the effect of alkylating agent N-methyl-N'- nitro-N-nitrosoguanidine (MNNG) with low concentration on JNK/SAPK and p38MAPK and the origins of JNK/SAPK and p38MAPK cascade.METHODS: p38 and JNK kinase activity were detected by immunoprecipitation and Western immunoblotting in intact and enucleated Vero cells.RESULTS: With the same experimental conditions, low concentration of MNNG inhibited JNK kinase in both intact cell and enucleated Vero cell. MNNG activated p38 kinase in intact cell while no effect on p38 kinase in enucleated cell was observed.CONCLUSION: Inhibition of JNK/SAPK by low concentration of MNNG was independ of a nuclear signal while MNNG activation of p38MAPK may depend on a nuclear signal.

Objective To explore the etiology and pathogenesis of Hirschsprung disease(HD) and the role of nitric oxide in pathophysiology of HD. Methods The whole amount preparations of dilative and transitional segments were stained by NADPH\|diaphorase histochemistry mothod,and colonic walls were digested by dispase. Then the NOS positive nervous structure were observed by light and scanning electron microscope. Results In dilative segment, under light microscope, ganglion and neuron were bigger and more darkly stained. Intraganglionic neurons distributed mostly in peripheral area of ganglion and basal part of ganglionic fiber bundles. Under scanning electron microscope, the neurons were denser, more nerve fibers from them and connected with each other in all dimensions. And more transverse connected fibers between neurons which were arranged along muscle fibers. Myenteric plexus even connected with the submucosal plexus by nerve fibers which passed through circular muscle layer. In transitional segment, under light microscope, intraganglionic neurons cytoplasm were lightly stained and also variedly. The ganglion and neurons of the segment were smaller, and the fibers from them were thinner and paler than those of the dilative segment. Under scanning electron microscope, neurons' density was lower, the fiber connection between neurons and muscle fibers/neurons was lesser. In the transitional segment, neurons and nerve fibers were distributed linearly along the longitudinal muscle fibers. Conclusion Our results indicated that an intimate relationship existed between the development of Hirschsprung disease and abnormal distribution and metabolism of NOS positive neuron in colonic wall. [