The present study investigated the enhanced radiosensitivity of U-251 cells induced by sodium butyrate (NaB) and its possible mechanisms. Increased radiosensitivity of U251 cells was examined by clonogenic cell survival assays. The expression of Ku70 mRNA and protein was detected by using RT-PCR and Western blotting respectively. γ-H2AX foci were measured at different time points after ionizing irradiation alone or combined with NaB treatment. The results showed that cell survival rate was significantly reduced, both D0 and Dq values were decreased (D0: 1.43 Gy vs. 1.76 Gy; Dq: 1.22 Gy vs. 2.05 Gy) after the combined treatment as compared with irradiation alone, and sensitivity enhancing ratio (SER) reached 1.23. The average number of γ-H2AX foci per cell receiving the combined treatment was significantly increased at different time points, and the expression levels of Ku70 mRNA and protein were suppressed by NaB in a dose-dependent manner. It was concluded that enhanced radiosensitivity induced by NaB involves an inhibited expression of Ku70 and an increase in γ-H2AX foci, which suggests decreased ability in DSB repair.

The present study investigated the enhanced radiosensitivity of U-251 cells induced by sodium butyrate (NaB) and its possible mechanisms.Increased radiosensitivity of U251 cells was examined by clonogenic cell survival assays.The expression of Ku70 mRNA and protein was detected by using RT-PCR and Western blotting respectively.γ-H2AX foci were measured at different time points after ionizing irradiation alone or combined with NaB treatment.The results showed that cell survival rate was significantly reduced,both D0 and Dq values were decreased (D0:1.43 Gy vs.1.76 Gy; Dq:1.22 Gy vs.2.05 Gy) after the combined treatment as compared with irradiation alone,and sensitivity enhancing ratio (SER) reached 1.23.The average number ofγ-H2AX foci per cell receiving the combined treatment was significantly increased at different time points,and the expression levels of Ku70mRNA and protein were suppressed by NaB in a dose-dependent manner.It was concluded that enhanced radiosensitivity induced by NaB involves an inhibited expression of Ku70 and an increase in γ-H2AX foci,which suggests decreased ability in DSB repair.

Objective:To investigate the impact of peak pressure upon different bone densities during autonomous puncture by orthopedic robot on puncture path deviation and bone cement leakage.Methods:A spinal surgery robot system was designed for autonomous vertebral puncture and bone cement injection, and six porcine spine specimens were used for single-segment or double-segment simulated percutaneous vertebral augmentation surgery. The accuracy of puncture path (Gertzbein-Robbins grading), bone cement leakage classification, and peak bone drill pressure were measured to assess the accuracy of autonomous vertebral puncture and bone cement leakage in vertebral cortical and cancellous bone of different densities.Results:A total of 64 porcine vertebrae were simulated for puncture, among which 53 vertebrae were classified as Grade A, 8 as Grade B, and 3 as Grade C according to the Gertzbein-Robbins grading. The cortical bone pressure of Grade A vertebrae was 6.663±0.319 N which was lower than that of Grade B (8.348±0.418 N) and Grade C (11.500±0.600 N), with significant differences ( F=341.000, P<0.001). The cancellous bone pressure of Grade A, B, and C vertebrae were 3.660±0.317, 3.594±0.608, and 4.117±0.257 N, respectively, with no significant difference ( F=2.496, P=0.091). There were 40 cases of no leakage, 20 cases of Type I leakage (leakage into the surrounding vertebrae), and 3 cases of Type II leakage (leakage into the vertebral canal), with an overall leakage rate of 36% (23/64). The peak cortical bone pressure for no leakage, Type I, and Type II leakage was 6.638±0.301, 6.792±0.404, and 6.753±0.473 N, respectively, and the peak cancellous bone pressure was 3.634±0.279, 3.783±0.423, and 3.920±0.255 N, respectively, with no significant difference ( F=1.521, P=0.227; F=2.106, P=0.131). Conclusion:During the autonomous puncture process of the novel orthopedic robot, the accuracy of autonomous puncture path decreased when the puncture pressure through the cortical bone was high, and the probability of invading the pedicle increased. The puncture pressure of cortical and cancellous bone had no significant effect on the occurrence rate of bone cement leakage.