Objective To explore the effect of collagen membrane combined with recombinant human bone morphogenetic protein-2(rhBMP-2) on periodontal tissue regeneration and repair in periodontal defect models of rats.Methods Eighteen male healthy Wistar rats,which were made experimental periodontal bone defects in the inferior incisors,were randomly divided into three groups:control group,collagen membrane group(Co),collagen membrane and rhBMP-2 group(Co/rhBMP-2).Two rats from each group were sacrificed at 4,6,8 weeks after operation.The mandibles were removed,and examined under light microscope.Results In Co/rhBMP-2 group: 4 weeks after operation,a large amount of bone formed in the defects;6 weeks later,new bone filled in the defects;8 weeks later,alveolar bone emerged,newly-formed periodontal ligament and cementum localized at the root edges,no gingival epithelium was observed.In Co group:4 weeks after operation,new bone formed at the edge of the defects;6 weeks later,a larger amount of bone and periost were observed;8 weeks later,a small amount of periodontal ligament and cementum localized at the root edges.In control group: 4 weeks after operation,there was a small amount of newly-formed bone at the edge of the defects;6 weeks later,collagen fibers were found at the edge of defects;8 weeks later,a small amount of periodontal tissue reached its original height and gingival epithelium proliferated obviously.Conclusion Collagen membrane combined with rhBMP-2 which has not only conductive effect but also effect of osteoinduction,can prevent the long-epithelium growing,maintain the growth gap,and promote periodontal tissue to regenerate.

【Objective】 To evaluate the effect of Arntl on T cell development and T cell-mediated anti-viral immunity. 【Methods】 Arntl^F/FCD4cre⁺(KO) in mice was constructed to delete Arntl gene specifically in T cells. We examined the percentage and number of T cell subsets in the thymus and spleen by flow cytometry (FCM). At day 8 after lymphocytic choriomeningitis virus (LCMV) infection, the proportions of T cell subsets, virus-specific CD8⁺ T cells and IFN-γ secreting T cells were analyzed. The viral load in the spleen was measured using qPCR. Naive CD4⁺ T cells (CD4⁺CD25^-CD44^-CD62L⁺) were sorted by flow cytometry to perform T helper cell differentiation in vitro. 【Results】 The percentage and number of T cells in the thymus and spleen of KO mice showed no significant change compared with those in the control group (Arntl^F/FCD4cre^- mice, WT) (P>0.05). Acute LCMV infection did not cause observable changes in effector T cell proportion in the spleen of KO mice compared to that in WT mice (P>0.05), but KO mice showed a higher proportion of IFN-γ secreting T cells (P<0.05) and better virus clearance (P<0.05). In addition, naive CD4⁺ T cells from KO mice were more prone to differentiate into Th1 cells in vitro (P<0.05). 【Conclusion】 Arntl deletion in T cells does not affect T cell development, but enhances their ability to defend against viral infection by promoting Th1 cell differentiation and response.