THE RELATIONSHIP BETWEEN mdrl GENE EXPRESSION AND DRUG-RESISTANCE IN OVARIAN CARCINOMA

Objective.To investigate the relationship between mdrl gene expression and multidrug-resistance in o- varian carcinoma. Design. We established tumor-bearing mice model of ovarian carcinoma,compared the anticancer drug sensitivity of OC/mdr-cell and OC/mdr+ cell in vitro, investigated the effect of cyclosporin A on reversing the multidrug resistance both in vitro and in the tumor-bearing mice model,detected the mdrl gene expre- sion in human ovarian carcinoma specimens. Main outcome measures. Anticancer drug sensitivity of both OC/mdr-cell and OC/mdr+ cell is mea- sured by the methods of MTT assays. mdrl gene expression is detected by the methods of RT-PCR. Results. Using MTT assay,OC/mdr+ cell is 4. 1 - 15. 5 times more resistant to VP-16,VCR,DNR, and DOX than OC/mdr-cell in vitro.2 μg/ml cyclosporine A(CsA)reduced the resistance of OC/mdr+ cell to DOX,from 0. 324±0. 072μg/ml to 0. 088±0. 024μg/ml. To OC/mdr－cell,CsA did not significantly in－ crease its sensitivity to DOX．Tumor-bearing mice with positive mdrl gene expression showed non-respon- siveness to DOX chemotherapy. When combined with intraperitoneal injection of CsA, the growth rate of tumor cells decreased significantly (P<0. 01 ). Only 4 of 23(17. 39% )tumors from patients who had not received chemotherapy exhibited positive mdrl gene expreession, while 6 of 9 (66. 67%)treated patients showed positive mdrl gene expression (Fisher exact test: P<0. 05 ). After cytoreductive surgery and chemotherapy, 14 of 19 untreated patients with negative mdrl gene expression had partial or complete re- sponse, while in patients with positive mdrl gene expression, 8 of 10 showed poor prognosis(Fisher exact test: P<0. 05 ). Conclusion. The expression of mdrl gene is associated with previous chemotherapy. CsA can reverse the resistance of mdr+ cells to indr-associated drs both in vitro and in vivo’ For the patients with ovarian carcinoma., the percentage of nonresponsiveness to the chemotherapy was found to be significantly higher among patients with positive mdrl gene expression than those with negative mdrl gene expression. mdrl gene expression can be detected to predict the clinical prognosis of patients with ovarian carcinoma.

In Situ Dissimilatory Nitrate Reduction to Ammonium in a Paddy Soil Fertilized with Liquid Cattle Waste

Most studies on dissimilatory nitrate reduction to ammonium （DNRA） in paddy soils were conducted in the laboratory and in situ studies are in need for better understanding of the DNRA process. In this study, in situ incubations of soil DNRA using ^15N tracer were carried out in paddy fields under conventional water （CW） and low water （LW） managements to explore the potential of soil DNRA after liquid cattle waste （LCW） application and to investigate the impacts of soil redox potential （Eh） and labile carbon on DNRA. DNRA rates ranged from 3.06 to 10.40 mg N kg 1 dry soil d-1, which accounted for 8.55%-12.36% and 3.88% 25.44% of consumption of added NO3-^15N when Eh at 5 cm soil depth ranged from 230 to 414 mV and -225 to -65 mV, respectively. DNRA rates showed no significant difference in paddy soils under two water managements although soil Eh and/or dissolved organic carbon （DOC） were more favorable for DNRA in the paddy soil under CW management 1 d before, or 5 and 7 d after LCW application. Soil DNRA rates were negatively correlated with soil Eh （P 〈 0.05, n = 5） but positively correlated with soil DOC （P 〈 0.05, n - 5） in the paddy soil under LW management, while no significant correlations were shown in the paddy soil under CW management. The potential of DNRA measured in situ was consistent with previous laboratory studies; and the controlling factors of DNRA in paddy soils might be different under different water managements, probably due to the presence of different microfioras of DNRA.