ABSTRACT
AIM: To explore whether tumor necrosis factor-α (TNF-α) induces necroptosis in murine long bone osteocyte-like cell line MLO-Y4 and the possible mechanism.METHODS: The MLO-Y4 cells were divided into control group, TNF-α group, TNF-α+necrostatin-1 (Nec-1) group, TNF-α+Z-VAD group and TNF-α+receptor-interacting protein 3 (RIP3)-siRNA group.The death rate of MLO-Y4 cells was assessed by flow cytometry with Annexin V-FITC/PI staining.The morphological features of the cells were observed under transmission electron microscope (TEM).The protein levels of RIP1, RIP3 and cleaved caspase-3 were determined by Western blot.Finally, the numbers of total cells and RIP1-RIP3-positive cells were observed under laser scanning confocal microscope.The production of reactive oxygen species (ROS) in the cells was measured by DCFH-DA staining.RESULTS: Compared with control group, the apoptotic or necroptotic rate of the cells induced by TNF-α was increased significantly (P<0.01).The increased apoptotic or necroptotic rate was dramatically reduced by treating with Nec-1, Z-VAD or RIP3-siRNA transfection (P<0.01).In TNF-α group and TNF-α+Z-VAD group, a lot of MLO-Y4 cells with typical necroptotic morphological features were observed under TEM.However, obvious necroptotic cells were not found in Nec-1 or RIP3-siRNA treatment group.The protein level of RIP1 in the cells treated with Nec-1 was sharply lower than that in TNF-α group (P<0.01).However, Z-VAD did not reduce the elevated levels of RIP1 and RIP3.RIP3-siRNA effectively down-regulated the protein level of RIP3 compared with TNF-α group (P<0.01).Nec-1 effectively down-regulated the protein levels of RIP1 colocalized with RIP3 compared with TNF-α group (P<0.01).However, Z-VAD did not reduce the levels of RIP1 colocalized with RIP3.Nec-1, Z-VAD and RIP3 siRNA significantly decreased the ROS levels (P<0.01).CONCLUSION: TNF-α induces the necroptosis of MLO-Y4 cells.RIP3 play vital roles in the cell necroptotic signal pathway.ROS may be the executor of necroptosis of MLO-Y4 cells.
ABSTRACT
Objective To evaluate the indications,techniques and effects of high speed drill assisted cervical pedicle screw-rod system in treatment of cervical interlocking dislocation.Methods A retrospective review was made on data of 13 cases of cervical interlocking dislocation undergone pedicle screw-rod fixation and reduction with assistance of high speed drills from December 2006 to July 2011.Dislocation localized in C3/4 (n =3),C4/5 (n =5),C5/6 (n =4) and C6/7 (n =1) respectively.Causes for injury contained cervical hyperextension due to traffic accidents (n =7) and a fall from the height (n =6).Two remained neurological intact,seven were combined with syndrome of central canal damage,and four had paraplegia.All the 13 cases received posterior pedicle screw fixation and reduction within 7 days after injury.Pedicle screws were implanted on adjacent segment of cervical spine with unlocking the interlocked small joints by a distraction device.Results All 13 cases obtained good reduction,including eight with complete anatomic reduction and five with 1-2 mm of vertebral slight slippage.Fifty-two screws were inserted and 49 pedicle screws were put in place except for the excursion in three pedicle screws on the postoperative radiographic and CT scans.There was no injury of spinal cord,nerve root or vertebral artery during operation.The patients showed significant improvement in sensory and motor function of the upper extremities in the follow-up of 12-36 months.One case had screw breakage at postoperative three months with no nerve symptoms.Conclusion High speed drill assisted pedicle screw-rod system is suitable for treatment of cervical interlocking dislocation,for its reduction process accords with the biomechanics and allows decompression therapy.