Objective To investigate the reversal effect on mdr1 gene mediated multidrug resistance in gastric cancer SGC7901/VCR cells by small interfering RNA(siRNA).Methods Two siRNAs(mdr1si2631 and mdr1si3071) specifically targeting mdr1 gene were designed and synthesized by transcription in vitro.The siRNA duplexes were used to transfect into the gastric cancer SGC7901/VCR cells.The expression levels of mdr1 mRNA and P-gp were detected by RT-PCR and immunohistochemistry respectively.The accumulation of intracellular adriamycin(ADR)was examined by flow cytometry and the cell sensitivity to ADR was demonstrated by MTT.Results The expression level of mdr1 mRNA treated by siRNAs for 48?hours was decreased in the SGC7901/VCR cells.The mdr1 RT-PCR product in the transfected mdr1si2631 SGC7901/VCR cells could hardly been found,similar to its parental SGC7901 cells,the ratio of mdr1 and ?-actin in the control SGC7901/VCR group was 1.05?0.10,the transfected mdr1si3071 group was 0.16?0.03(P0.05).The RT-PCR results showed that the mdr1 mRNA expression level in the mdr1 si2631 group decline more obviously than that in the mdr1si307l group,near by the level in its parental SGC7901 cells.The P-gp immunoreactivity(IR)in brownish-colored granules was located on the cell membrane.The P-gp IR became weaker in the SGC7901/VCR cells treated by siRNAs for 48 hours and the P-gp expression level in both transfected siRNA groups was decreased.The values of adriamycin-specific fluorescence intensity and the positive rates of intracellular ADR in both transfected siRNA groups were increased.The relative reversal efficiency of the SGC7901/VCR cells to ADR detected by MTT was 79.59%in mdr1 si2631 group and 59.98%in mdr1si3071 group respectively.Conclusion siRNA could reverse mdr1 gene mediated multidrug resistance in gastric cancer SGC790l/VCR cells.

Objective To improve the efficiency and quality of end-to-end anastomosis,a novel degradable vascular anastomotic device was designed,and the relationship between pressure distances and biomechanical properties of the anastomotic stoma was explored.Methods The three-dimensional(3D)structure of the vascular anastomotic device was designed and the prototype was fabricated with extruded high-purity magnesium.The finite element model of the end-to-end vascular anastomosis was established to study the stress distributions of the anastomotic end face under different pressure distances(0.4,0.5,0.6,0.7,and 0.8 mm)and their change rules.In vitro experiments were conducted to verify the rationality of the finite element results as well as the feasibility and effectiveness of the vascular anastomotic device.Results When the pressure distance was 0.6 mm,the anastomotic tensile force,and burst pressure could reach(11.79±0.64)N and(39.32±2.99)kPa,respectively,meeting the clinical requirement for the strength of vascular anastomosis,and with the minimal mechanical damages to tissues.Conclusions The device designed in this study can be used for vascular anastomosis by adjusting the pressure distance,and it can improve operation efficiency,reduce mechanical damage to tissues,and further improve the quality of anastomosis.These results provide an essential reference for the design of degradable vascular anastomotic devices.