Objective To investigate the cytotoxic effects and mechanism of PNP-CD chimeric gene vector originated from PNP/MeP-dR system on HCC cells. Methods The fusion suicide gene PNP-CD obtained by site directed mutagenesis technique was subcloned into pcDNA3.0 to construct a eukaryotic expression vector containing a chimeric gene, pcDNA3.0/ PNP-CD. After being identified by recombinant enzyme, PCR and subsequent sequencing, it was transfected into HepG2 cells by liposome-mediation method. The G418-resistant cellular clone with stable transfection of pcDNA3.0/PNP-CD, HepG2/PNP-CD was established by selection. The expression of PNP-CD gene was also verified by RT-PCR and Western blotting. The curve of cellular growth was assayed by Trypan blue exclusion. The cellular sensitivity of HepG2/PNP-CD to its specific prodrugs and its bystander effects were also assayed by MTT method. Results The chimeric gene, PNP-CD, was inserted into pcDNA3.0 correctly, and the stable expression of pcDNA3.0/PNP-CD in HepG2 cells was confirmed.This cellular clone was highly sensitive to its corresponding prodrugs. It was indicated that its bystander effects with the synergetic treatment of its specific prodrugs were substantially higher than those caused by the same vector with the administration of only a single prodrug, MeP-dR. Conclusion The bi-functional fusion suicide gene vector, pcDNA3.0/PNP-CD, yields powerful cytotoxic effects on HCC cells in the presence of the synergetic treatment of its specific prodrugs, which would be a high-performance therapeutic vector in gene therapy for liver cancer.

BACKGROUND: The clinical application of one-level osteotomy and multilevel osteotomy has been well documented, but currently few studies were reported to compare their biomechanical characteristics.OBJECTIVE: To investigate the biomechanical characteristics of one-level osteotomy with Dick screw fixation and multilevel osteotomy with Luque instrumentation in the treatment of kyphosis.DESIGN: Randomized comparative experiment.SETTING: Laboratory of the Department of Orthopedics, Renmin Hospital of Wuhan University.MATERIALS: Fresh specimens of thoracic and lumbar spinal segments obtained from 12 3 or 4-year-old calves.METHODS: The experiment was conducted in the laboratory of the Department of Orthopedics, Renmin Hospital of Wuhan University between September 2002 and September 2003. Fresh spinal segments T8-L5 from 12 calves were randomized into an intact group, Dick screw group with one-level osteotomy with Dick screw fixation and Luque group with multilevel osteotomy with Luque instrumentation, with 4 spesimens in each group. Lateral bending test of the specimens was performed to examine the physiological overload using an Instron 5 500 universal material testing machine at the constant speed of 10 mm/minute until fracture or dislocation was induced. Changes in the loading were recorded and the induced injuries observed to obtain the load-displacement curve of the injury test.MAIN OUTCOME MEASURES: The load-displacement curve of the destructive right bending test in each group.RESULTS:All the data of 12 canines were involved in the result analysis.The spinal segments of the intact group yielded to the force of 3 600 N with a flat and smooth load-displacement curve, and those of Dick screw group yielded to a load of 2 800 N with also a relatively flat curve, while in Luque group, the segments did not yield until a load of 7 160 N, followed by drastic decrease of the resistance to less than 4 000 N, generating a flat and smooth curve afterwards.CONCLUSION: Luque instrumentation is a little more preferable than Dick screw in terms of the maximum resistance, but this difference does not justify the clinical decision of their superiority. Both techniques benefit postoperative recovery of spinal function with strong stability.

Immunotherapy which has been in practice for more than 20 years proves effective for the treatment of metastatic renal cell carcinoma (mRCC). Anti-angiogenesis-targeted therapy has recently been identified as a promising therapeutic strategy for mRCC. This study was aimed to evaluate the effectiveness of vascular endothelial growth factor (VEGF) pathway-targeted therapy for mRCC by comparing its effectiveness with that of immunotherapy. The electronic databases were searched. Randomized controlled trials (RCTs) on comparison of VEGF inhibiting drugs (sorafenib, sunitinib and bevacizumab) with interferon (IFN) or placebo for mRCC treatment were included. Data were pooled to meta-analyze. A total of 7 RCTs with 3451 patients were involved. The results showed that anti-VEGF agents improved progression-free survival (PFS) and offered substantial clinical benefits to patients with mRCC. Among them, sunitinib had a higher overall response rate (ORR) than IFN (47% versus 12%, P<0.000001). Bevacizumab plus IFN produced a superior PFS [risk ratio (RR): 0.86, 95% confidence interval (CI): 0.76-0.97; P=0.01] and ORR (RR: 2.19; 95% CI: 1.72-2.78; P<0.00001) in patients with mRCC over IFN, but it yielded an increase by 31% in the risk of serious toxic effects (RR: 1.31; 95% CI: 1.20-1.43; P<0.00001) as compared with IFN. The overall survival (OS) was extended by sorafenib (17.8 months) and sunitinib (26.4 months) as compared with IFN (13 months). It was concluded that compared with IFN therapy, VEGF pathway-targeted therapies improved PFS and achieved significant therapeutic benefits in mRCC. However, the risk to benefit ratio of these agents needs to be further evaluated.

Immunotherapy which has been in practice for more than 20 years proves effective for the treatment of metastatic renal cell carcinoma (mRCC).Anti-angiogenesis-targeted therapy has recently been identified as a promising therapeutic strategy for mRCC.This study was aimed to evaluate the effectiveness of vascular endothelial growth factor (VEGF) pathway-targeted therapy for mRCC by comparing its effectiveness with that of immunotherapy.The electronic databases were searched.Randomized controlled trials (RCTs) on comparison of VEGF inhibiting drugs (sorafenib,sunitinib and bevacizumab) with interferon (IFN) or placebo for mRCC treatment were included.Data were pooled to meta-analyze.A total of 7 RCTs with 3451 patients were involved.The results showed that anti-VEGF agents improved progression-free survival (PFS) and offered substantial clinical benefits to patients with mRCC.Among them,sunitinib had a higher overall response rate (ORR) than IFN (47％ versus 12％,P＜0.000001).Bevacizumab plus IFN produced a superior PFS [risk ratio (RR):0.86,95％ confidence interval (CI):0.76-0.97; P=0.01] and ORR (RR:2.19; 95％ CI:1.72-2.78; P＜0.00001) in patients with mRCC over IFN,but it yielded an increase by 31％ in the risk of serious toxic effects (RR:1.31; 95％ CI:1.20-1.43; P＜0.00001) as compared with IFN.The overall survival (OS) was extended by sorafenib (17.8 months) and sunitinib (26.4 months) as compared with IFN (13 months).It was concluded that compared with IFN therapy,VEGF pathway-targeted therapies improved PFS and achieved significant therapeutic benefits in mRCC.However,the risk to benefit ratio of these agents needs to be further evaluated.