BACKGROUND:Surgical accuracy is a key to surgical success.The traditional positioning method mainly depends on surgeons' experience,which is too subjective to cause screw misplacement.Three-dimensional (3D) printing technology-assisted pedicle screw placement can make individualized surgical scheme,most importantly,it is accurate and simple showing promising application prospect.OBJECTIVE:To design an individualized pedicle guide plate with 3D printing and to simulate screw placement in vitro,and to explore its feasibility in vertebral pedicle screw placement.METHODS:Lumbar spine CT data of 11 patients with degenerative lumbar spine were selected from April 2016 to July 2016 at Hebei General Hospital,and 3D reconstruction of L1,L3 and L5 vertebrae of each case was performed.Pre-experiment was conducted based on one patient's lumbar CT data:according to the principle of screw placement,the screw position and orientation were designed to prepare the best pedicle guide plate model.Afterwards,the screw placement in vitro was simulated,and was then cut by chainsaw to verify the accuracy of screw placement.RESULTS AND CONCLUSION:(1) A total of 30 pedicle guide plates were used,and 60 screws were inserted in the patients,and the placement process was successful.The guide plates adhered well,none appeared with screw perforating the pedicle cortex,and the screw position was accurate and reliable.(2) There were no significant changes in the transverse section and sagtial section angles of the left and right pedicle screws before and after placement (P ＞ 0.05).(3) These results suggest that the 3D-printed individualized pedicle guide plate holds a good accuracy of placement,which can be applied in the vertebral pedicle screw placement,but further clinical trials are needed.

Objective: To observe the effects of nootkatone on depression-like behavior, neurogenesis and protein kinase A(PKA)/cyclic adenosine monophosphate response element-binding protein(CREB)/brain-derived neurotrophic factor(BDNF) signaling pathway in hippocampus of chronic unpredictable stress(CUS) treated mice, and to explore the role and molecular mechanism of nootkatone′s antidepressant effect. Methods: Male C57 BL/6 mice were randomly divided into 3 groups: the control group(saline), the CUS group(CUS+saline), the CUS+nootkatone group(CUS+nootkatone). The sucrose preference test and forced swim test were used to evaluate the depression-like behaviors. The mRNA expression of BDNF in hippocampus was measured by RTPCR. The expression levels of BDNF, PKA and phosphorylated cyclic adenosine monophosphate response element-binding protein(p-CREB) in hippocampus were determined by Western blot. The level of neurogenesis was measured by immunofluorescence. Results: Compared with the control group, the sucrose preference decreased(P<0.05) and the latency decreased(P<0.05), and immobility time increased in forced swim test(P<0.05) in CUS group, the expression levels of BDNF mRNA(P<0.05) and protein(P<0.05), PKA(P<0.05) and p-CREB(P<0.05) decreased. The sucrose preference of the CUS+nootkatone group increased(P<0.05) and the latency increased(P<0.05), and immobility time decreased in forced swim test(P<0.05), the expression levels of BDNF mRNA(P<0.05) and protein(P<0.05), PKA(P<0.05) and p-CREB(P<0.05) increased in comparison with the CUS group. Compared with control group, the number of hippocampal doublecortin(DCX) labeled neurons decreased(P<0.05) in CUS group. Compared with the CUS group, the number of DCX labeled neurons increased in the CUS+nootkatone group(P<0.05). Conclusion The improvement of depressive symptoms in CUS mice by nootkatone may be related to the neurogenesis in dentate gyrus of hippocampus and the activation of PKA/CREB/BDNF signaling pathway.