0 05). The individuals with 677CT and 677CT+TT genotypes had a 0 21 fold [95% confidence interval(CI), 0 43 0 99] and 0 26 fold (95%CI,0 07 0 98) reduced risk of developing gastric cardia cancer compared with those with 677CC genotype. The individuals with 677TT genotype had a 3 63 fold (95%CI,1 04 12 72) increased risk of developing gastric corpus cancer. MTHFR 677CT polymorphism was not correlated with H.pylori infection in gastric cancer. Conclusion The polymorphism of MTHFR 677CT is associated with increased risk of gastric corpus cancer and reduced risk of gastric cardia cancer, but not with H.pylori infection

Objective To establish the orthotopic human pancreatic cancer model in mice and study the method to detect the tumor growth. Methods Human pancreatic cancer cell lines SW1990 in logarithmic phase was made into cell suspension and in situ injected into the envelope of pancreatic tail of BALB/c nude mice. High-frequency endoscopy ultrasound was used to observe the growth of tumor mass and its imaging characteristics were studied. Results 20 nude mice were successfully implanted, and 1 died 25 h after implantation. 14 days after implantation, the tumor of pancreatic cancer on EUS was (8.09 ± 2.61) mm3, the tumor appeared as homogeneous hypoechoic mass with clear boundary, and envelope as well as sound halo was present, and the shape was regular; there was low speed circular vasculature signal in around 30% of tumor.The tumor size increased to (12.40 ± 3.51)mm3, and the shape of 70% tumor was irregular, and some appeared as lobulated, and the tumor appeared as heterogeneous hypoechoic mass, no necrosis or liquefaction was found 28 days after implantation. There was low speed circular vasculature signal in around 70% tumors.Conclusions The orthotopic pancreatic cancer model in nude mouse can be established by in situ injection and this method is relatively ideal because it is simple and effective. The high frequency probe of endoscopic ultrasonograph is a reliable method for monitoring implanted pancreatic cancer.

Objective To investigate the effect of Iodine 125 seeds short time low dose rate irradiation on perineural invasion (PNI) in pancreatic cancer Capan-2 cells,and explore its molecular mechanism.Methods The co-culture model was established by co-culturing the dorsal root ganglion (DRG) of SD rat and Capzn-2 cells line,while Capan-2 culture model and DRG culture model was also established.Iodine 125 seeds short time low dose rate irradiation tablet was used for the 3 models,and the model without irradiation was used as control.Cancer cell and DRG growth was observed under inverted microscopy,surface of neurite and cell colony growth was determined by image analysis software.The concentration of nerve growth factor (NGF),transforming growth factor-α (TGF-α) in cell culture supernatant and matrigel solution was tested by ELISA,and the expression of neurotrophin-3 (NT-3) mRNA was detected by semi-quantitative reverse transcriptase polymerase chain reaction (RT-PCR).Results In the co-culture model,neurite of DRG showed a direction to cancer cells and had a concentrated growth towards cancer cells.And Capan-2 cells formed more colonies towards neurite.However,in irradiation groups,the symbiotic phenomenon was inhibited to some degree.Increased surface of neurite in co-culture model at 5th day was 290.15 ± 12.08,which was significantly higher than that in DRG group (124.83 ± 6.96,P ＜ 0.01),but the surface of neurite was decreased to 201.53 ± 12.20 after irradiation (P ＜0.01).Increased surface of Capan-2 cell was 300.47 ± 12.99,which was significantly higher than that in Capan-2 group (199.30 ± 8.60,P ＜ 0.01),but the surface of Capan-2 was decreased to 202.35 ± 7.97 after irradiation (P ＜ 0.01).NT-3 mRNA was seldom or not expressed in supernatant of co-culture model,but it was strongly expressed (0.68 ± 0.04) after irradiation (P ＜ 0.05).The concentration of NGF and TGF-α in supernatant of co-culture model were (27.56 ± 13.73),(40.86 ± 20.73) ng/ml,after irradiation they were increased to (94.98 ± 33.80),(157.54 ± 83.76) ng,/ml,and the difference between the two groups was statistically significant (P＜0.05 or ＜0.01).The concentration of NGF and TGF-α in matrigel lysate of co-culture model were (60.42 ± 33.03),(64.39 ± 21.52)ng/ml,after irradiation they were increased to (132.52 ±53.01),(138.38 ±83.58)ng/ml,and the difference of NGF concentration between the two groups was statistically significant (P ＜ 0.05).Conclusions Iodine-125 seeds short-time low-dose rate irradiation could inhibit interactions between nerve and Capan-2 cells,and the mechanism may be related to up-regulation of cancer cells perineural invasion promoter NGF,TGF-α and NT-3.