BACKGROUND:Pedicle screw is the major instrumentation of surgery in thoracic spine. However, there have been few reports about pedicle morphology relevant to screw insertion tracts, and few reports comparing the normal adolescents and adolescent idiopathic scoliosis patients. OBJECTIVE:To compare the morphologic characteristics of the thoracic pedicle with regard to safe thoracic pedicle screw placement in normal adolescents and adolescent idiopathic scoliosis patients. METHODS: Thoracic pedicles of thirty-five normal adolescents and thirty-five adolescent idiopathic scoliosis patients were measured with three-dimensional reconstruction CT images. Measured parameters include (1) critical distance: the shortest distance from an entry point to the ventral cortex of the lamina. (2) Safe distance: the distance from the entry point to the tangent of the spinal canal at the medial wal of the pedicle. (3) Pedicle screw length. (4) Pedicle width. (5) Pedicle transverse angle. The dangerous area was defined as the distance between the critical distance and the safe distance. RESULTS AND CONCLUSION: The mean critical distance was (9.2±1.0) mm for the normal adolescents, and (9.4±1.2) mm for the adolescent idiopathic scoliosis patients. Safe distances were significantly less in normal adolescents (14.7±0.8) mm than that of the adolescent idiopathic scoliosis group (15.4±1.4) mm (P < 0.001). The dangerous area was (5.4±0.7) mm for the normal adolescents, which was significantly less than that of the adolescent idiopathic scoliosis patients (6.0±1.0) mm (P < 0.001). Pedicle screw length was (36.6±4.1) mm for the normal adolescents and (37.1±5.3) mm for the adolescent idiopathic scoliosis patients. Pedicle width was (5.8±1.2) mm for the normal adolescents and (5.7±1.7) mm for the adolescent idiopathic scoliosis patients. No significant difference in critical distance, pedicle screw length and pedicle width was found between the two groups (P=0.382, 0.135, 0.293). Pedicle transverse angle decreased gradualy from T1 to T12 in both groups. These results verify that pedicle morphology of many parameters is different between normal adolescents and adolescent idiopathic scoliosis patients, especialy in the apical area of the thoracic curve.

Objective To discuss the short-term currative effect of horizontal osteotomy across injured vertebral forⅤdegree old frac-ture-dislocations of thoracolumbar spine.Methods The data of 4 patients who received horizontal osteotomy across injured vertebral internal fixation in our hospital from April 2010 to October 2012 were retrospectively analyzed,of which 1 case with T8-9 fracture dislocation,2 cases with T10-11 fracture dislocation,1 case with T11-12 fracture dislocation.The Franke1 classification of all patients were grade A.Results All 4 cases were achieved completely fracture reduction and followed-up for 2-14 months(an average of 7.4 months),who could get sitting posi-tion with the support of brace 1 week after operation.The postoperative follow-up indicated that all 4 cases got fusion,but there was no improve-ment for Franke1 classification.Conclusion The method of horizontal osteotomy across injured vertebral forⅤdegree old fracture-dislocations of thoracolumbar spine has good short-term clinical effect,with the advantages of shorter operation time,less bleeding and good reduction effect.

Objective: To compare the clinical effects of robot-assisted minimally invasive transforaminal lumbar interbody fusion (TLIF) and traditional open TLIF in the treatment of lumbar spondylolisthesis. Methods: A total of 41 patients with lumbar spondylolisthesis accepted surgical treatment in Department of Spinal Surgery of Beijing Jishuitan Hospital From July 2015 to April 2016 were retrospectively analyzed. There were 16 cases accepted robot-assisted minimally invasive TLIF and 25 accepted traditional open TLIF. The operation time, X-ray radiation exposure time, perioperative bleeding, drainage volume, time of hospitalization, time for pain relief, time for ambulatory recovery, visual analogue scale (VAS), Oswestry disability index (ODI) and complications were compared. T test and χ² were used to analyze data. Results: There were no significant difference in gender, age, numbers, degrees, pre-operative VAS and ODI in spondylolisthesis (all P>0.05). Compared with traditional open TLIF group, the robot-assisted minimally invasive TLIF group had less perioperative bleeding ((187.5±18.4) ml vs. (332.1±23.5) ml), less drainage volume ((103.1±15.6) ml vs. (261.3±19.8) ml), shorter hospitalization ((7.8±1.9) days vs. (10.0±1.6) days), shorter time for pain relief ((2.8±1.0) days vs. (5.2±1.1) days), shorter time for ambulatory recovery ((1.7±0.9) days vs. (2.9±1.3) days) and less VAS of the third day postoperatively (2.2±0.9 vs. 4.2±2.4) (t=2.762-16.738, all P<0.05), but need more operation time ((151.3±12.3) minutes vs. (102.2±7.1) minutes) and more X-ray radiation exposure ((26.1±3.3) seconds vs. (5.5±2.1) seconds) (t=6.125, 15.168, both P<0.01). In both groups ODI was significantly lower in final follow-up than that of the pre-operation (t=12.215, 14.036, P<0.01). Intervertebral disc height of the final follow-up in both groups were significantly larger than that of the preoperation (robot-assisted minimally invasive TLIF group: (11.8 ± 2.8) mm vs. (7.5 ± 1.9) mm, traditional open TLIF group: (12.7 ± 2.5) mm vs. (7.9±2.0) mm), and so was the lumbar lordosis angle (robot-assisted minimally invasive TLIF group: (48.7±9.2)°vs. (39.6±7.9)°, traditional open TLIF group: (50.1±10.8)°vs. (41.4±8.8)°), the lordosis angle of the slippage segment (robot-assisted minimally invasive TLIF group: (18.7±5.6)°vs. (10.9±3.8)°, traditional open TLIF group: (17.6±6.1)°vs.(8.7±3.2)°) (t=4.128-16.738, all P<0.01). Slippage rate of the final follow-up in both groups were significantly smaller than those of the pre-operation (robot-assisted minimally invasive TLIF group: (5.3±2.3) % vs. (27.8±7.2) %, traditional open TLIF group: (6.6±2.8) % vs. (29.1±9.5) %) (t=11.410, 18.504, both P<0.01). There was no difference of the upper data between two groups (t=0.106-1.227, P>0.05). The results of the post-operative CT showed that the pedicle screws in the robot-assisted minimally invasive TLIF group were more precisely placed than traditional open TLIF group (χ²=4.247, P=0.039). The mean follow-up time was 8 months (ranging from 3 to 12 months). There were no significant difference in outcomes between the two groups (χ²=0.366, P=0.545). Conclusions In the treatment of lumbar spondylolisthesis, Robot-assisted minimally invasive TLIF can lead to less perioperative bleeding, less post-operative pain, and quicker recovery than traditional open TLIF surgery, but it needs more operation time and radiation exposure.

Objective:To evaluate the pancreatic subclinical dysfunction after intensity-modulated radiation therapy (IMRT) for gastric cancer by analyzing biochemical indexes and pancreatic volume changes, and to reduce the dose of pancreas by dosimetric prediction and dose limitation.Methods:30 patients with gastric cancer who received 45 Gy postoperative adjuvant radiotherapy were retrospectively selected. The pancreas was delineated and its dose and anatomical relationship with planning target volume (PTV) were evaluated. Fasting blood glucose, serum lipase and amylase, and pancreatic volume changes before and after radiotherapy were analyzed. The correlation between the changes of biochemical indexes and volume and pancreatic dose was evaluated by Pearson analysis. The threshold of the dosimetric prediction was obtained by receiver operating characteristic (ROC) curve. Finally, the feasibility of dosimetric limitation in IMRT was assessed.Results:The pancreatic volume of 30 patients was 37.6 cm 3, and 89.0% of them were involved in PTV. D mean of the pancreas was 45.92 Gy, and 46.45 Gy, 46.46 Gy and 45.80 Gy for the pancreatic head, body and tail, respectively. The fasting blood glucose level did not significantly change. The serum lipase levels were significantly decreased by 66% and 77%(both P<0.001), and the serum amylase levels were significantly declined by 24% and 38%(both P<0.001) at 6 and 12 months after radiotherapy. Pancreatic volumes of 22 patients was decreased by 47% within 18 months after radiotherapy. ROC curve analysis showed that pancreatic V 45Gy had the optimal predictive value for the decrease by 1/3 of serum lipase and amylase levels at 6 months and serum amylase level at 12 months after radiotherapy, and the cut-off value was V 45Gy<85%. Pancreatic D mean yielded the optimal predictive value for the decrease by 2/3 of serum lipase level at 12 months after radiotherapy, and the cut-off value was D mean<45.01 Gy. After" whole pancreas" and" outside PTV pancreas" dose limit, V 45Gy of the pancreas was decreased by 11% and 7%, D mean of the pancreas was declined by 2% and 2%, and D mean of the pancreatic tail was decreased by 3%, respectively. Conclusions:Serum lipase and amylase levels significantly decline at 6 and 12 months after adjuvant radiotherapy for gastric cancer, and pancreatic volume is decreased significantly within 18 months after radiotherapy. Pancreatic V 45Gy<85% and D mean<45.01 Gy are the dose prediction values for the decrease of serum lipase and amylase levels. The dose can be reduced to certain extent by dosimetric restriction.

Objective:To investigate the impact of intermittent senescent cell clearance on the proliferation and differentiation of dental pulp stem cells (DPSC) in long-term, large-scale expansion, and to explore strategies for maintaining the youthful state of DPSC in vitro. Methods:Human-derived dental pulp stem cells were isolated from healthy permanent teeth extracted for orthodontic or impeding eruption reasons, provided by the Department of Oral and Maxillofacial Surgery at West China Hospital of Stomatology, Sichuan University. Long-term, large-scale in vitro expansion of DPSC was conducted. The study compared young DPSC (passage 5) with aged DPSC (passage 25) using cellular senescence-associated β-galactosidase staining, colony formation assay, and Alizarin Red S staining for osteogenic differentiation induction. To assess the differences between the two cell populations in terms of senescence and amplification and differentiation ability. Medicine screening for the most effective senolytic was compared among 5 common senolytics [Navitoclax (ABT-263), curcumin, dasatinib, fisetin, and quercetin]. The clearance efficacy was compared using cellular senescence-associated β-galactosidase staining to reflect the changes in senescent cell ratio. The senolytic with the highest efficacy was chosen for further experiments. The passage at which the proportion of senescent cells significantly increased was identified, and the selected senolytic was administered three times at three-generation intervals from that passage to remove senescent cells. Both the control and senolytic-treated groups were estimated by fluorescence cellular senescence-associated β-galactosidase staining, real-time fluorescence quantitative PCR (RT-qPCR), colony formation assay, wound healing assay, and Alizarin Red S staining for osteogenic differentiation induction. Subcutaneous heterotopic osteogenesis was performed in nude mice and the grafts were analyzed by HE staining and alkaline phosphatase (ALP) immunohistochemical staining. Results:The proportion of senescent cells increased as the expansion extended, leading to decreased proliferation and osteogenic differentiation ability of senescent DPSC compared to young DPSC ( P<0.05). Senescent DPSC exhibited altered mRNA expression levels of senescence-related genes, including p21, p16INK4a, IL-6, and Ki67 ( P<0.001). Among the five senolytics, ABT-263 had the biggest decreases in the proportion of senescent cells. After intermittent ABT-263 treatment during expansion, the proportion of senescent cells in the senolytic-treated group [(6.72±2.34)%] was significantly lower than that in the control group [(31.82±0.57)%] ( P<0.001). RT-qPCR confirmed that compared with the control group, mRNA expressions of p21, p16 INK4a, and IL-6 in the senolytic-treated group were significantly decreased ( P<0.05), while mRNA expressions of Ki67 were significantly increased ( P<0.01). Furthermore, the cell healing ability and osteogenic differentiation ability of the senolytic-treated group were higher than those of the control group ( P<0.05). In vivo experimental results indicated that the relative new bone area [(2.36±0.48)%] after DPSC transplantation in the senolytic-treated group was greater than that in the control group [(1.00±0.46)%] ( P<0.05), and the expression of ALP was higher than that in the control group ( P<0.01). Conclusions:ABT-263 can effectively eliminate senescent cells in long-term large-scale DPSC expansion. Continuous treatment with ABT-263 during cultivation can maintain the proliferation and differentiation ability of DPSC both in vivo and in vitro.