Objective To investigate the feasibility of achieving consistent image quality with dose reduction technology in lumber spine MSCT examination with Z-axis automatic tube current modulation (ATCM). Methods Forty-eight patients diagnosed as lumber intervertebral disc protrution scanned twice by MSCT before and after interventional operations with the same coverage from third lumbar vertebra to first sacral vertebra. The first scan (FM) was with fixed tube current of 320 mAs. The follow-up scan was with ATCM with noise index (NI) of 12.0 HU. At the levels of L3-4, L4-5 and 15-S1, image quality, image noise and radiation dose were measured and analyzed. Image quality and radiation dose were compared by paired t-test and the image noise was compared by ANOVA test. Results The dosage of the ATCM had a 31.3% reduction compared with FM, the average DLP was(187.9±66.4)mGy·cm and(273.4±45.4) mGy·cm respectively, where t = 8.205, P < 0.05. The average noise and their deviations for the FM group were (9.8±2.4) HU,(9.9±2.4) HU, and (11.5±3.2) HU at level of L3-4, L4-5, 15-S1, respectively. With ATCM, the average noise was(12.0±0.8) HU, (11.7±0.6) HU, and (11.7±1.4) HU, respectively. There was statistical difference between the two groups (F = 23.31, P < 0.05). The image quality scores for the FM group were (4.7±0.3), (4.5±0.2), (4.5±0.2) and showed no statistical difference to ATCM group (4.6±0.3), (4.5±0.2), (4.5±0.2) at level of L3-4, L4-5, L5-S1, respectively, where t = 1.000, P > 0.050 Conclusion ATCM technique with the noise index setting at 12.0 HU can achieved a 31.3% dose reduction while keep the consistent image quality for lumbar spine MSCT study.

Objective To evaluate the clinical application value of multi-slice helical CT volumetric (VH) scanning in lumber spine. Methods One thousand of patients with back and leg pain who underwent CT examinations were selected as subjects. We simulated the traditional protocol of single-slice(SS) discrete scanning for L3/4, L4/5, and LS/S1 intervertebral discs. The VH scanning mode was performed with 120 kV, 210 mAs,pitch of 1.5 and coverage of 97. 5 mm. The simulated SS scanning mode was performed with 120 kV, 240 mAs and coverage of 45.0 mm. The diagnostic outcomes and the radiation doses were compared between the two scanning modes. Two groups doctors observed ten terms, including the osseous spinal stenosis,narrowed intervertebral space and so on in two scanning modes respectively. Then consistency analysis of the data was carried out. Results The VH scanning mode showed far more features than the SS mode. The detection rates of the VH mode in the osseous spinal stenosis, narrowed intervertebral space,herniated nucleus pulposus, narrowed lateral recess, vertebral lesion, hypertrophy of L5 transverse process,abnormal direction of facet, facet degeneration, lumbar spondyloschisis, and paraspinal soft tissue were 11.8% (n =118), 38. 5% (n =385), 9. 3% (n =93), 46. 8% (n =468), 31.4% (n =314), 5.7% (n =57), 25.4% (n = 254), 49. 7% (n = 497), 9.9% (n = 99), and 0. 6% (n = 6) respectively, while the detection rates of the SS mode in ten terms were 5.6% (n = 56), 0, 0. 6% (n = 6), 27. 9% (n = 279),22.4% (n =224), 1.2% (n = 12), 16.7% (n = 167), 37.2% (n =372), 0.5% (n =5), and 0.2%(n = 2) respectively. The difference between the two groups had statistically significance (average P <0.05), except the paraspinal soft tissue abnormal (P > 0.05). The detection rates of the VH mode were higher than the SS mode in the osseous spinal stenosis, narrowed intervertebral space, herniated nucleus pulposus, lumbar spondyloschisis, being 6.2% (n = 62) , 38. 5% (n = 385) , 8.7% (n = 87), and 9.4%(n =94), respectively. In addition, VH mode only partially showed the articular facets, narrowed lateral recess, hypertrophy of L.5 transverse process, and paraspinal soft tissue. We could not acquire the imaging slices paralleling to intervertebral discs in SS mode in 467 patients (46.7%) with lumbosacral angle greater than 35°. The radiation dose of VH mode (164.9 mGy/em) was slightly higher than SS mode (147.0 mGy/cm) Conclusion MSCT VH scanning mode can significantly improve the diagnostic rate of lumbar spine diseases compared with SS mode, and was not restricted by the lumbosacral angle with slightly increasing radiation dosage.

Objective:To investigate the inhibitory effect and underlying mechanism of gamma-secretase inhibitor blocking Notch1 signaling on retinal neovascularization caused by oxygen-induced retinopathy (OIR) in mice.Methods:To establish the OIR model, 7-day-old pups of C57BL/6J mice were exposed to 75% oxygen together with their mother until postnatal day (P)12.On P12, the mice were transferred to room air.All the mice were randomly divided into three groups, OIR group as control group, OIR+ DAPT group and OIR+ DMSO group receiving 1 μl intravitreal injection of gamma-secretase inhibitor (DAPT, 10 mmol/L) and 1∶20 DMSO dilution respectively.The right eye was taken as experimental eye.The mice were euthanized on P17 and the eyes were harvested to obtain retinas for further investigation.The total proteins were extracted from the retinas.The relative expression levels of Notch1 signal pathway and its downstream Hes1, the markers of M1 phenotype inducible nitric oxide synthase (iNOS) and M2 phenotype arginase-1 (Arg-1) microglia were measured by western blot.Retinal flat mounts were made and the retinal vessels were stained with isolectin B4 (IB4) to investigate the relative retinal neovascularization areas which was calculated as the ratio of neovascularization area/retinal area.The mumber of the neovascular endothelium cells beyond the inner limiting membrane was observed by hematoxylin-eosin staining.The use and care of animals complied with ARVO statement.This study protocol was approved by the Animal Ethics Committee of Guangdong Provincial People's Hospital (No.KY-Z-2021-2015-01).Results:The relative protein expression levels of Notch1 and Hes1 in OIR+ DAPT group, OIR group, and OIR+ DMSO group were 0.68±0.06 and 0.70±0.08, 1.00±0.00 and 1.00±0.00, 1.03±0.08 and 1.02±0.07, respectively, with statistically significant differences among them ( F=70.62, 53.65; both at P<0.01). Compared with the OIR group and OIR+ DMSO group, the expressions of Notch1 and Hes1 were significantly reduced in OIR+ DAPT group (all at P<0.01). The relative protein expression levels of iNOS and Arg-1 in OIR+ DAPT group, OIR group, and OIR+ DMSO group were 0.74±0.07 and 1.49±0.12, 1.00±0.00 and 1.00±0.00, 1.04±0.10 and 0.94±0.07, respectively, showing statistically significant differences ( F=31.63, 89.32; both at P<0.01). Compared with OIR group and OIR+ DMSO group, the expression of iNOS in OIR+ DAPT group was significantly reduced, and the expression of Arg-1 was significantly increased (all at P<0.01). The relative neovascularization area and the number of neovascular endothelium cells beyond the inner limiting membrane in OIR+ DAPT group, OIR group, and OIR+ DMSO group were (8.82±2.71)% and 38.17±3.29, (22.32±5.34)% and 60.83±5.11, (20.27±3.36)% and 58.67±4.75, respectively, showing statistically significant differences ( F=33.72, 39.44; both at P<0.01). The relative neovascularization area and the number of neovascular endothelium cells in OIR+ DAPT group were significantly reduced in comparison with OIR group and OIR+ DMSO group (all at P<0.01). Conclusions:Intravitreal injection of DAPT can inhibit the retinal neovascularization in OIR mice through blocking Notch1 signaling activation and promoting retinal microglia polarization from M1 to M2 phenotype.

Objective To study the influence of hollow screws with five kinds of spatial distributions on the fixation effect of femoral neck fracture. Methods Geometric models of femoral neck fracture with Pauwels type I, II and III were built by reverse engineering according to CT images of the femur. Based on the finite element analysis software ANSYS, the stress distributions of internal fixation, head side and stem side of femoral neck and the displacement distributions of the model fixed by different methods were obtained. Results For femoral neck fracture with Pauwels type I, II and III, the maximum stresses at head side of femoral neck were the inverted triangle fixation method, two-screw parallel fixation method, two-screw parallel fixation method, respectively. The maximum stresses at stem side of femoral neck were the inverted triangle fixation method, inverted triangle fixation method and two-screw parallel fixation method, respectively. The minimum stresses on the screws were the cross fixation method, and the minimum displacements of the model were double-supported fixation method. Conclusions The probability of screw deformation and fracture is the smallest for cross fixation method. Inverted triangle fixation method can provide a good mechanical environment for fracture site. For femoral neck fracture with Pauwels typeⅠ and Ⅲ, double-supported fixation method has the strongest ability to prevent femoral neck shortening. While for femoral neck fracture with Pauwels typeⅡ, cross fixation method has the strongest ability to prevent femoral neck shortening.

In order to stimulate students' interest in orthodontics and develop their competency in self-directed learning,innovation and practice,we introduced "maker education" into the orthodontics course for undergraduate.In the early stage,the teaching materials were organized based on fragmentation of learning,and the "maker group" is the basic unit.In class,the topics were discussed in the form of flipped classroom.Finally,a series of orthodontic experiments were carried out.This article can provide new ways to improve the quality of orthodontics education.

OBJECTIVE：To study the improvement effect and mechanism of MEBO on lipopolysaccharide （LPS）-induced injury of rat skin fibroblasts. METHODS ：Skin fibroblasts of rats were divided into control group ，LPS group （5 μg/mL）， Kangfuxin solution group （positive control ，5 μg/mL LPS+1.25％ Kangfuxin solution ）and MEBO group （5 μg/mL LPS+0.6 mg/mL MEBO），with 6 wells in each group. Inflammatory injury cell model was induced by LPS （except for control group ）. After a certain period of cultivation ，the cell survival rate and cell migration rate were detected in each group. The contents of TNF-α and IL-6 in cell supernatant was detected. The localization and fluorescence intensity of IL- 6 protein were detected. The protein expression of PTEN ，p-p65，TNF-α，IL-6，PI3K and Akt in the fibroblasts were also determined. RESULTS ：Compared with control group ，survival rate of the fibroblasts was increased significantly in LPS group ，while cell migration was decreased significantly；the contents of TNF-α and IL-6 in cell supernatant as well as relative protein expression of PTEN ，p-p65，TNF-α， IL-6 and PI 3K were increased significantly （P＜0.05 or P＜0.01）；IL-6 protein mainly expressed in the cytoplasm ，and the fluorescence intensity was enhanced. Compared with LPS group ，survival rate of the fibroblasts was decreased significantly in Kangfuxin solution group and MEBO group ，while migration rate was increased significantly ；the contents of TNF-α and IL-6， relative protein expression of PTEN ，p-p65，TNF-α，IL-6（except for Kangfuxin solution group ），PI3K and Akt （except for Kangfuxin solution group ） were decreased significantly （P＜0.05 or P＜0.01），while fluorescence intensity of IL- 6 protein decreased；relative protein expression of TNF-α，IL-6，PI3K and Akt in MEBO group were significantly lower than Kangfuxin solution group （P＜0.05 or P＜0.01）. CONCLUSIONS ：MEBO can inhibit the proliferation of LPS-induced skin fibroblasts ， reduce the level of inflammatory factors and the intensity of inflammatory reaction ， which may be related to the jiang- down-regulation of PTEN/NF-κB，PI3K/Akt signaling pathway.