BACKGROUND:The biomechanical effect of the implant-bone interface is one of the most important factors for bone resorption. The new structure of the periodontal-ligament-like implants may improve the distribution of the interfacial stress. OBJECTIVE:To discuss the effect of the internal structure changes of traditional implants on the cortical bone stress distribution and peak at the implant-bone interface under different occlusal load conditions, so as to provide a theoretical basis for the optimization design and clinical application of new structure implants. METHODS:Two kinds of digital models, new structure implant (model A) and non-threaded cylindrical implant (model B), were established by Pro/ENGINEER software. Variations of the stress peak and stress distribution of implant-bone interface cortical bone area under the same bone and force environment were analyzed using Ansys software. RESULTS AND CONCLUSION: Under a vertical loading, the stress peak under different forces was reduced by 17.54% in model A compared with model B; under a 45° loading, the stress peak of model A was reduced by 2.59% compared with model B, and it showed an evident tendency of high stress area focusing to the buccal side of model B. Under the chew-simulation loading, the stress peak of model A was lower than that of model B. The biggest difference (0.353 2 MPa) appeared atβ=12°(β is the angle of force direction and the implant axis), and it gradualy reduced atβ > 12°. At the same time, model A had a wider range of application degree compared with model B in two quantitative indicators, including optimal peak stress of promoting bone tissue growth and stress peak of maintaining healthy bone tissue. These results suggest that the optimized structure of implants contributes to improve the cortical bone stress distribution at the implant-bone interface, decrease the peak stress, and reduce the risk of cortical bone absorption in a wider range.

Objective To observe the effect of δ-opioid receptor on proliferation and migration of human epidermal stem cells (hESCs) in vitro so as to offer treatment theory for skin injury.Methods hESCs from fresh foreskin tissues of normal young volunteers were isolated and cultured by enzyme digestion and differential adherence technique.Immunofluorescent staining was used to determine expression of integrin β1 and cytokeratin 19 (CK19) and flow cytometry was used for cell count.Second generation of cells were cultured for 5 consecutive days with keratinocyte serum-free medium (K-SFM) supplemented with 1 nmol/L (D-Ala2,K-Leu5)-enkephalin in Group A,with K-SFM supplemented with 1 nmol/L naltrindole and 1 nmol/L (D-Ala2,K-Leu5)-enkephalin in Group B,and with isolated K-SFM in Group C.Cellular division and proliferation were detected by MTT method.An in vitro 100 μm scratch-wound model was created on the confluent monolayer cells at 24 hours of incubation.Cells migrating from the wound margin were determined by inverted phase contrast microscope at 24,48,72,and 96 hours after wound formation,while wound closure rate was calculated at 72 hours.Results Primary cultured hESCs presented cobblestone-like shape after adherence growth,Immunofluorescence staining showed positive results for integrin β1 and CK19 and cell purity reached 95.6％.Moreover,MTT findings revealed proliferation of hESCs enhanced significantly in Group A,but lowered in Group B as compared to Group C (P ＜ 0.05).hESCs migrated from the wound margin in all groups at 24 hours.However,more migrated cells were seen in Group A than in Group C and less in Group B than in Group C.Rate of wound closure was (89.5 ±0.7)％ in Group A,(76.1 ±0.3)％ in Group B,and (81.1 ±0.6)％ in Group C at 72 hours,indicating significant differences among groups (P ＜ 0.05).Conclusion Activation of δ-opioid receptor promotes the proliferation and migration of hESCs in vitro and may be implicated in wound healing.

Objective To investigate the expression of lysyl oxidase like protein?2(LOXL?2)in the sera of patients with active systemic scleroder?ma(SSc)and mixed connective tissue disease(MCTD). Methods An enzyme?linked immunosorbent assay was adopted to measure LOXL?2 in the serum of 20 patients with active SSc,20 patients with active MCTD,and 20 healthy controls. The measurements among different groups was com?pared,and correlations between LOXL?2 levels and clinical manifestations of SSc and MCTD were examined. Results The levels of LOXL?2 ex?pression in MCTD and SSc groups were significantly higher than those in control group(P<0.05 for all groups). LOXL?2 expression is also related to the presence of skin lesions in SSc(r=0.982 P=0.001). Conclusion High serum level of LOXL?2 in these patients with active SSc and active MCTD suggests that LOXL?2 may be involved in the process of fibrosis and the resulting vasculitis in multiple organs.

Objective To explore any changes in the surface electromyography (sEMG) signals measured on the spastic upper limb muscles of stroke parents during maximum isometric voluntary contraction and to analyze any abnormal synergy patterns quantitatively in order to design better rehabilitation programs for developing coordination.Methods Ten stroke survivors with hemiparesis were selected into a patient group and ten healthy counterparts were recruited into a control group.sEMG signals were recorded bilaterally from the flexor carpi ulnaris (FCU),biceps brachii (BB),triceps brachii (TB) and deltoid (D) during maximum isometric voluntary contractions involving wrist flexion and extension,elbow flexion and extension,and shoulder abduction.The two groups' co-contraction ratios (CR) and co-activation ratios were calculated and compared.Results During elbow flexion and extension the average CR of the BB on the affected side was significantly higher than that on the unaffected side and also significantly higher than the control group average.The average CR of the TB on the affected side was significantly higher than that of the healthy controls.In all cases the average CR of the BB was larger than that of the TB.The difference in CR between the TB and the BB on the affected side was significantly larger than on the unaffected side and the control group average.During elbow flexion,the co-activation ratio of the FCU,TB and D on the affected side was significantly higher than on the unaffected side and among the healthy controls,and the co-activation ratio of the FCU on the affected side was significantly higher than that of the D and TB.During elbow extension,the co-activation ratio of the FCU,BB and D on the affected side was significantly higher in the same way,and the co-activation ratio of the FCU on the affected side was again significantly higher than that of the D and BB.During wrist flexion,the average co-activation ratio of the BB and D on the affected side was significantly greater than that on the unaffected side and among the healthy controls,and the co-activation ratio of the BB on the affected side was significantly higher than that of the D and TB.During shoulder abduction,the co-activation ratio of the BB on the affected side was significantly larger than on the unaffected side and among the healthy controls.Conclusion After a stroke the upper limbs often show flexor spasticity and abnormal synergy patterns.Rehabilitation strategy should be adopted to tackle these so as to enhance overall limb coordination.

Objective To investigate bone age of left-hand wrist in healthy adolescents of Shenyang and Beijing for assessing the process of skeletal development.Methods From 2008 to 2012,1333 adolescents (aged form 4.0 to 18.0 ys) of Shenyang and Beijing were enrolled in this study.Skeletal age was estimated by left hand and wrist X-ray using CHN atlas by 2 qualified radiologists.The correlation between skeletal and chronological age was analyzed using correlation analysis.Skeletal age and chronological age were compared using paired t test.The differences between skeletal and chronological age in genders and regions were compared using independent-samples t test.SPSS for Windows (version 13.0)was used for statistical analysis.P ＜ 0.05 was considered as significant difference.Results (1) Close correlation was found between skeletal age and chronological age (P ＜ 0.01) for both two genders and two regions.(2)Among 28 groups of investigation,16 groups (boys,11 groups) had higher skeletal ages than chronological ages with statistical significance,including Shenyang boys aged 6.0-18.0 ys,Shenyang girls aged 6.0-7.9 ys and 14.0-15.9 ys,Beijing boys at 6.0-15.9 ys and Beijing girls at 8.0-13.9 ys.(3) Comparison between boys and girls:5 groups showed significant difference,including 8.0-9.9 ys,10.0-11.9 ys and 16.0-18.0 ys groups in Shenyang and 6.0-7.9 ys,10.0-11.9 ys groups in Beijing.(4) Comparison between Shenyang and Beijing:6 groups showed statistical significance,including boys at 10.0-11.9 ys,12.0-13.9 ys and 16.0-17.9 ys and girls at 6.0-7.9 ys,8.0-9.9 ys and 10.0-11.9 ys.Conclusion Although CHN atlas method could reflect adolescent bone development,the skeletal age is higher than chronological age in many groups,and the difference between skeletal and chronological age is statistically different between genders and between two regions.This research can be used as a reference for the study of skeletal development and for further emendation of CHN atlas.

Objective To evaluate the effect of problem-based learning (PBL)versus tradi-tional methods in medical statistics. Methods Computer retrieval was conducted to search for con-trolled studies comparing PBL and traditional methods. The quality of included studies was critically evaluated and data were analyzed by using the Cochrane Collaboration's RevMan 5.0 software. Results A total of 21 articles were retrieved,but only 7 were included. The results of Meta analysis showed that there was no significant difference between PBL and traditional methods in both the passing rate of student's score (RR=1.09,95%CI=0.98-1.23,P=0.12>0.05)and the exact score (WMD=0.30, 95%CI=-0.06 -0.67,P=0.10>0.05). Conclusion PBL showed no better learning results in medical statistics compared with traditional methods.

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Objective To investigate the expressions of ABCG2 and V-ATPase in NSCLC and their expression rates in pathological classification, TNM stages and pathological grades and the expression correlation between ABCG2 and V-ATPase. Methods Expressions of ABCG2 and V-ATPase were accessed with EnVinsion immunohistochemistry in tumor samples from 92 NSCLC patients. The corresponding data was analyzed statistically. Results Expressions of ABCG2 and V -ATPase were found both in the lung adenocarcinoma and lung squamous cell cancer, and the difference between these two kinds of tumors was significant (P =0.003,0.000). ABCG2 expression was significantly different among TNM stages of lung adenocarcinoma (P=0.004) as well as among pathological grades of lung adenocarcinoma (P =0.028) and squamous cell carcinoma (P =0.000), while no significant difference was found among TNM stages of squamous cell lung carcinoma. The level of V-ATPase expression was associated with TNM stages of lung adenocarcinoma (P =0.026) and pathological grades of lung squamous cell carcinoma (P =0.002), however, among TNM stages of lung squamous cell carcinoma and pathological grades of lung adenocarcinoma, the difference was not significant. Additionally, the significant correlation was found between expression of ABCG2 and V-ATPase in all samples, adenocarcinoma and squamous cell carcinoma (P<0.001). Conclusion The significant correlation is found between expression of ABCG2 and V-ATPase, which indicate that they may co-work to participate in the mechanism of anticancer drug resistance.

Objective To detect the genetic toxicity of a neotype in situ polymeric injectable artificial prosthetic nucleus pulposus.Methods The artificial prosthetic nucleus pulposus was soaked for preparing the leaching liquor which was used for tests of genetic toxicity.Salmonella typhimurium reverse mutation test(Ames Test),mammalian cell chromosome aberration(CA) test utilizing Chinese hamster ovary cells(CHO),and mouse micronucleus(MN) test were performed to detect the genetic toxicity of the extraction,including the effects on DNA,chromosome aberration and genetic mutation.Results The number of reverse mutation strains,from five strains of every dosage group,was all lower than half of quantum of control group,with or without the addition of S9,in the Ames Test,which assessed as negative.In CA test,no significant difference of chromosome aberration rate existed among the high,medium and low concentration group,while the CA rate of all the three groups was lower than that of the negative group(P0.05),but significantly lower than that of the positive control group(P

Objective To evaluate the value of 99mTc-MIBI SPECT positive tumor imaging and MRI in the diagnosis of recurrence and postoperative residual of glioma. Methods Of 30 cases of glioma, 21 cases were residual or recurrent of glioma, while 9 cases were not, confirmed by pathology or follow-up. 99mTc-MIBI SPECT positive tumor imaging and MRI were performed on all patients. Results The sensitivity of 99mTc-MIBI SPECT positive tumor imaging (80.1%)was lower than that of MRI (90.5%) (χ2 = 0.006 4,P = 0.035), while the specificity of 99mTc-MIBI SPECT(88.9%) was much higher than that MRI(77.8%)(χ2= 3.827,P = 0.006). The accuracy in diagnosing residual or recurrent glioma between the two imaging has no significant difference. The sensitivity, specificity and accuracy were 95.2%, 100% and 93.3% when the two imaging methods were combined. Conclusions 99mTc-MIBI SPECT positive tumor imaging has higher specificity in the diagnosis of recurrence and postoperative residual of glioma. The combination of 99mTc-MIBI SPECT positive tumor imaging and MRI has great clinical significance.