Objective To investigate the effect of different bone cement volume injected after vertebroplasty on stress distribution of the upper and lower endplates of the injured vertebra in the flexion and extension positions by finite element analysis.Methods Two patients with osteoporotic compression fractures of L2 vertebral body were chosen.Bone cement volumes of 25％ and 50％ were respectively injected into the fractured vertebral body bilaterally.Pre-and post-operative finite element models of fractured and adjacent vertebral bodies were developed after extracting the CT data.Stress changes at L2 superior-and inferior-vertebral endplates were observed in the vertical,flexion,and extension loading.Results Stress at the upper and lower endplates of the fractured vertebra increased after bone cement injection and more increase was observed in 50％ bone cement group than in 25％ bone cement group.In the neutral position,the stress mainly concentrated at posterior vertebral body,with stress of the upper endplate improving from 0.91 × 106 N · mm to 0.93 × 106 N · mm and stress of the lower endplate from 0.98 × 106 N ·mm to 1.03 × 106 N · mm.In the anterior flexion,the stress mainly concentrated at anterior vertebral body,with stress of the upper endplate improving from 4.44 × 106 N · mm to 5.55 × 106 N · mm.In the posterior extension,the stress mainly concentrated at medial vertebral body,with stress of the upper endplate improving from 21.95 × 106 N · mm to 22.10 × 106 N · mm and stress of the lower endplate from 30.60 ×106 N · mm to 30.88 × 106 N · mm.The finite element model revealed stress at the upper and lower endplates was higher in the anterior flexion and posterior extension than in the neutral position,while in the anterior flexion the stress was comparatively higher.Conclusions A small amount of implanted bone cement act no evident effect on stress distribution of the upper and lower vertebral endplates.However,the stress changes are significant as cement volume reached up to 50％,especially in the flexion position,as may suggest an enhanced risk of adjacent intervertebral disc degeneration and adjacent vertebral body fractures.

Objective To investigate the changes in the number of microglias and astrocytes in the spinal dorsal born in a rat model of phantom limb pain.Methods Eleven healthy adult SD rats of both sexes weighing 290-300 g were randomly divided into 2 groups:sham operation group (group S,n =5 ) and unilateral sciatic nerve transection group (group SNT,n =6).Phantom limb pain model was induced by resection of a 0.5 cm segment of unilateral sciatic nerve in group SNT.In group S unilateral sciatic nerve was exposed but not transected.The animals were observed for autotomy and scored (0 =no autotomy,13 =the worst autotomy) after operation and were sacrificed on the 28th day after operation.The L5 segment of the spinal cord was removed for determination of the number of microglials (by iba-1 immuno-histochemistry) and astrocytes (by GFAP immuno-histochemistry).Results In group S no animal developed autotomy.In group SNT autotomy started from the 2nd day after operation and the score reached 9-11.Compared with group S,the number of the microglias and astrocytes in the spinal dorsal horn was significantly decreased in the operated side in group SNT ( P ＜ 0.05 ).Conclusion The number of microglias and astrocytes in the spinal dorsal horn is decreased in animals with phantom limb pain.

Objective To investigate the changes in the number of synapses and neurons in the spinal dorsal horn in a rat model of phantom limb pain. Methods Eleven healthy adult SD rats of both sexes weighing 209-300 g were randomly divided into 2 groups: sham operation group (group S, n = 5) and phantom limb pain group (group P, n = 6). Phantom limb pain was induced by resection of a 0.5 cm segment of unilateral sciatic nerve in group P. In group S unilateral sciatic nerve was exposed but not transected. The animals were observed for autotomy and scored (0 = no autotomy, 13 = the worst autotomy) after operation and were sacrificed on the 28th day after operation. The L3-6 segment of the spinal cord was removed for determination of the number of neurons (by Nissl's staining) and synapses (by synaptophysin immuno-histochemistry).Results In group S no animal developed autotomy. In group P autotomy started from the 2nd day after operation and the score reached 9-11. The number of the neurons in the spinal dorsal horn in all 4 segments and the number of synapses in L3 and 16 segments were comparable between the two sides and the 2 groups. The number of synapses in the spinal dorsal horn of L4and L5 segment was significantly larger in the operated side than in the contralateral side in group P. Conclusion The number of synapses in the spinal dorsal horn significantly increases in animals with plantom limb pain which induces no increase in the number of neurons in the spinal dorsal horn.

Objective To evaluate the value of MRI in acute ankle distortion without evidence of fracture. Methods The MRI appear-ances of 21 cases with acute trauma in the ankles were retrospectively analyzed,focusing on the presence or absence injuries of lateral collat-eral ligamentous complex,bone and osteochondral lesions,MRI was performed within 48 h of trauma. Results Bone bruise was observed in 15 patients. There were injuries of the lateral ligaments in 4 cases and the medial ligaments in 1 case. Injury of the osteochondral lesion was in 5 cases and Achilles tear was in 3 cases. Conclusion MRI have diagnostic value for acute ankle injury.

Objective:To investigate the current status of satisfaction with training program and loyalty to the university among professional postgraduate students majoring in clinical medicine, as well as the association between satisfaction with training program and loyalty to the university.Methods:The 2017 National Medical Student Satisfaction Survey Database was used. A total of 1 944 professional postgraduate students in the second or third year, as well as those with delayed graduation, from 59 postgraduate training colleges and universities who participated in clinical internship were selected. SPSS 20.0 software was used for analysis; descriptive analysis was used to describe satisfaction with training program and loyalty to the university; factor analysis was adopted to calculate comprehensive satisfaction score to reduce the number of variables; logistic regression analysis was applied to investigate the association of general information and satisfaction with training program with loyalty to the university.Results:The professional postgraduate students majoring in clinical medicine had a degree of 60.44% of loyalty to the university. Satisfaction with training program reflected low satisfaction at each link of the training program. For every 1-point increase in the comprehensive satisfaction scores of the four links of courses, research training, college support, and practice, the loyalty to the university was increased to 2.11, 1.83, 1.77, and 1.75 times as the original, respectively, of the baseline scores.Conclusion:There is still room for further improvement in the satisfaction with training program and the loyalty to the university among professional postgraduate students majoring in clinical medicine, and the satisfaction with training program is closely associated with the loyalty to the university. Colleges and universities need to take measures for courses, practice, research training, and college support, so as to improve satisfaction and thus enhance loyalty to the university.

Objective To evaluate the efficacy of point application combined with catgut implantation at acupoint for lung-distention. Methods A total of 122 patients with lung-distension were randomized into a treatment group (62 patients) and a control group (60 patients). The patients in the control group received conventional treatment, and those in the treatment group were additionally treated with point application combined with catgut implantation at acupoint on the basis of the control group for 4 weeks. At 6 months follow-up, pulmonary function including the forced expiratory volume in first second (FEV1) and the percentage of FEV1 to forced vital capacity (FEV1/FVC), the total effective rate and acute exacerbation rate were compared in both groups. Results The total effective rate in the treatment group was significantly higher than that in the control group (98.4%vs. 85.0%;χ2=5.592, P<0.05). There were no significant difference in the acute exacerbation rate between the treatment group and the control group (8.1%vs. 20.0%;χ2=3.358, P>0.05).The FEV1 (treatment group: 71.58% ± 2.23% vs. 59.98% ± 2.19%, t=29.223, P<0.01; control group: 66.99% ± 2.25% vs. 61.03% ± 2.50%, t=13.726, P<0.01) and the FEV1/FVC (treatment group:68.99%± 1.33%vs. 50.77%± 1.45%, t=72.914, P<0.01; control group: 62.67% ± 1.47% vs. 51.89% ± 1.88%, t=34.989, P<0.01) after the treatment were significantly increased compared with before the treatment in both groups and such improvement in the treatment group was greater in the treatment group than that in the control group (FEV1: t=13.726, P<0.01;FEV1/FVC:t=34.989, P<0.01). Conclusion Point application combined with catgut implantation at acupoint can improve lung function and clinical effects in patients with lung-distention.

Vitreous hemorrhage in children is caused by trauma or non-traumatic factors.Long-term vitreous hemorrhage not only affects children's vision,but also can lead secondary glaucoma,traumatic retinal detachment and other serious complications.Ocular trauma,some ocular and systemic diseases are the common etiology leading to vitreous hemorrhage in children.A small amount of vitreous hemorrhage can be treated by observation and conservative treatment.However,if the vitreous hemorrhage has no obvious absorption or serious complications appeared,it needs to be treated by surgery.The choice of treatment time and methods need to be further studied.

Objective:To investigate the MRI features of perirenal space involvement in patients with acute pancreatitis (AP) and its correlation with disease severity.Methods:A total of 128 AP patients admitted to Bishan District People′s Hospital of Chongqing from June 2018 to June 2020 were selected as study subjects. All patients were diagnosed by ultrasound guided percutaneous biopsyand the pathological diagnosis results were taken as the gold standard. The accuracy, sensitivity and specificity of MRI diagnosis were calculated to analyze the correlation between MRI features of perirenal space involvement and MRI severity index (MRSI).Results:Among the 128 patients, 96 patients with perirenal space involvement in AP confirmed by ultrasound guided percutaneous biopsyand the pathological diagnosis results, accounted for 75.00%. The sensitivity, specificity, accuracy, positive predictive value and negative predictive value diagnosed by MRI were 95.83%, 93.75%, 95.31%, 97.87% and 88.24% respectively. The involvement rate of perirenal space in AP was 75.00%(96/128), and that in mild, moderate and severe AP was 52.38%(22/42), 93.62%(44/47) and 7/7, respectively. Forty-two mild patients presented abnormal signals in the pancreas, or focal and diffuse pancreatic enlargement, thickening, and abnormal streak signalabnormalities in perirenal space, perirenal MRI showed grade 1 and 2. Forty-seven patients with moderate disease showed patchy signal abnormalities in the perirenal space, and perirenal MRI showed grade 3. Seven severe patients found perirenal interstitial effusion which was patchy. There was a good correlation between MRI features grade of perirenal space involvement and MRSI ( r = 0.721, P<0.001). The consistent rate of MRI features score of the right perirenal space was 91.14%, the consistent rate of MRI features score of the left perirenal space was 95.38%, and the consistent rate of MRSI observation on both was 90.21%. Conclusions:MRI can effectively and accurately diagnose perirenal space involvement in AP patients, MRI features and involvement rate can accurately reflect the severity of AP, which has a positive effect on clinical diagnosis and treatment of patients with perirenal space involvement in AP.

OBJECTIVEThe migrant population is a vulnerable group for HIV infection in China. Understanding potential epidemic trends among migrants is critical for developing HIV preventative measures in this population.

METHODSThe Estimation and Projection Package (EPP) model was used to process prefecture and county-level surveillance data to generate HIV prevalence and epidemic trends for migrant populations in China.

RESULTSThe prevalence of HIV among migrants in 2009 was estimated at 0.075% (95% CI: 0.042%, 0.108%) in China. The HIV epidemic among migrants is likely to increase over the next 5 years, with the prevalence expected to reach 0.110% (95% CI: 0.070%, 0.150%) by 2015.

CONCLUSIONAlthough the 2009 estimates for the HIV/AIDS epidemic in China indicate a slower rate of increase compared with the national HIV/AIDS epidemic, it is estimated to persistently increase among migrants over the next 5 years. Migrants will have a strong impact on the overall future of the HIV epidemic trend in China and evidence-based prevention and monitoring efforts should be expanded for this vulnerable population.

China ; epidemiology ; Condoms ; Epidemics ; statistics & numerical data ; Female ; HIV Infections ; epidemiology ; Humans ; Male ; Models, Theoretical ; Prevalence ; Risk Factors ; Safe Sex ; Sexual Behavior ; Transients and Migrants

Objective To investigate the effect of minocycline(Mino)on the polarization of types M1/M2 microglia(pro-and anti-inflammatory type)in the spinal dorsal horn of rats with neuropathic pain(NP)induced by spinal nerve ligation(SNL)and its underlying mechanism.Methods A total of 36 adult male SD rats were randomly stratified into Sham-operation(Sham)group,SNL group and Mino+SNL group by stratified random sampling based on body weight.Mechanical pain threshold and cold nociceptive thresholds of rat hind paw were measured in 1 d before and 14 d after modelling.Spinal cord tissue at the lumbar 5(L5)segment was taken at 14 d after modelling,and the total number of microglia as well as the numbers of M1 and M2 microglia in the spinal dorsal horn were measured with immunohistochemistry and stereology.With aid of bioinformatics techniques,the core target in the spinal cord,Cst7,was selected.Then,the protein levels of microglia marker Iba-1,M1 microglia marker iNOS,M2 microglia marker CD206,Cst7 encoded protein cystatin F(CF)and pathway CatS/CX3CL1/CX3CR1 were detected with Western blotting.The expression levels of TNF-α,IL-6 and IL-10 in the spinal cord tissues were measured with ELISA.Results The mechanical pain and cold nociceptive thresholds were both significantly higher in the M+SNL group than the SNL group at 7～14 d after modelling(P＜0.01).The total number of microglia and the numbers of M1/M2 microglia in the spinal dorsal horn as well as the expression levels of CatS,CX3CL1,CX3CR1,TNF-α,IL-6,and IL-10 in the spinal cord tissues were obviously increased,and the expression level of CF was notably decreased in the SNL model group than the Sham group(P＜0.01).While,Mino treatment remarkably reversed above phenomena,with decreased total number of microglia and number of M1 microglia as well as expression levels of CatS,CX3CL1,CX3CR1,TNF-α and IL-6,and increased number of M2 microglia as well as CF and IL-10 levels when compared with the SNL group(P＜0.05).Conclusion Mino alleviates SNL induced neuropathic pain,probably through up-regulating CF in the microglia,and thus inhibiting the CatS/CX3CL1/CX3CR1 signaling pathway,promoting the conversion of microglia from type M1 to M2 to balance the imbalance in the M1/M2 polarization,and thus reducing neuroinflammation.