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 analyze the trend of the burden of leukemia among people under 35 years in China from 1990 to 2019. Methods: Incidence, mortality and disability-adjusted life years (DALY) of leukemia among people under 35 years in China from 1990 to 2019 were collected by using the Global Burden of Disease (GBD) Study Database 2019. The trends in leukemia incidence, mortality and DALY rates were analyzed using the average annual percent change (AAPC) and age-period-cohort model. Results: From 1990 to 2019, the incidence, mortality and DALY rates of leukemia among people under 35 years in China showed a downward trend (AAPC=-2.336%, -3.604% and -3.589%, all P<0.05), with more pronounced downward trends in females (AAPC=-3.209%, -3.787% and -3.818%, all P<0.05) than in males (AAPC=-2.521%, -3.292% and -3.306%, all P<0.05). According to the age-period-cohort model, the risks of leukemia incidence, mortality and DALY rates decreased with increasing age. Among them, the children under 5 years had the highest risks of leukemia incidence, mortality and DALY rates (RR=4.697, 2.718 and 3.059). Over time, the risks of leukemia incidence, mortality and DALY rates also decreased from 1990-1994 (RR=1.217, 1.264 and 1.296) to 2015-2019 (RR=0.901, 0.696 and 0.691). With regard to birth cohorts, the risks of leukemia incidence, mortality and DALY rates first increased and then decreased, peaking in the 1986-1990 birth cohort (RR=1.335, 1.192 and 1.231). Conclusions The incidence, mortality and DALY rates of leukemia among people under 35 years in China from 1990 to 2019 showed a downward trend. Males and children under 5 years were the key populations for leukemia prevention and control.

Objective To study the expression of B7-H1 in gastric mucosa of patients with gastric carcinoma,and to identify its relationship with neoplasm metastasis and prognosis.Methods Expression of B7-H1 in gastric carcinoma cell line SGC-7901 and in freshly-resected gastric mucosa including gastric carcinoma,adjacent tumor tissue and distal normal gastric mucosa were examined by flow cytometric analysis,immunochemical staining,immunofluorescence staining and Western blot.The correlated data was analyzed statistically.And so the correlation among expression level of B7-H1 and the patients,clinicopathological parameters was established.Results B7-H1 expression was detected in SGC-7901 cell line.B7-H1 was found in cell membrane and little cytoplasm.The positive rate of B7-H1 expression in gastric carcinoma was(13/21)62%,and it was(7/21)33% in adjacent tumor tissue,Whereas B7-H1 was absent in distal normal gastric mucosa.Statistical analysis demonstrated a positive correlations of B7-H1 expression in gastric carcinoma with the depth of carcinoma infiltration,lymph node metastasis and pTNM stage(P