Objective To explore the effect of cannabinoid receptor 2(CB2)on orthodontic tooth movement(OTM)rate and periodontal tissue reconstruction of pressure area in mice.Methods Thirty CB2-/-male mice and thirty littermate control WT male mice were individually accepted the orthodontic appliance at their age of 6 weeks.The mice were respectively scarified at 3 days,7 days,14 days and 21 days after the operation.Then the tooth movement distance was examined through the stereomicroscope.Hematoxylin-eosin staining was performed to explore the biological responses of periodontium at the distal mesial root pressure area.Anti-tartrate acid phospha-tase staining was performed to calculate the number and distribution of osteoclasts at the distal mesial root pressure area,and MMP-9 was evaluated by immunohistochemistry to examine the number of MMP-9(+)monocytes and multinucleated cells in the same district as the TRAP staining.Results Compared with those WT mice at 3,7,14 and 21 days,OTM distance showed a gradual increased tendency according with experimental time over 21 days.The widths of periodontal ligament on the pressure side were markedly greater in CB2-/-mice than WT mice at 7,14 and 21 days(P＜0.000 1).The numbers of TRAP positive osteoclasts were significantly greater in CB2-/-mice than those in WT mice at 14 days of OTM(P＜0.001).MMP-9 immunohistochemical staining showed that the number of MMP-9(+)monocytes and multinucleated cells was more in CB2-/-mice than that in WT mice at 14 days of OTM(P＜0.05).Conclusion The absence of CB2 accelerates orthodontic tooth movement under or-thodontic force.The absence of CB2 reinforces bone resorption in orthodontic tooth movement compressive area dur-ing orthodontic tooth movement.

Objective To investigate the association of ideal cardiovascular health metrics with the incidence rate of nonalcoholic fatty liver disease (NAFLD), and to provide a basis for the prevention and control of NAFLD. Methods A prospective cohort study was conducted for the data of 50 511 employees of Kailuan Group who participated in physical examination from July 2006 to June 2007, and the onset of NAFLD was observed during follow-up once every two years. A one-way analysis of variance was used for comparison of normally distributed continuous data between multiple groups, and the Kruskal-Wallis H test used for comparison of continuous data with skewed distribution between multiple groups; the chi-square test was used for comparison of categorical data between groups. The subjects were divided into four groups according to the quartile of cardiovascular health score (CHS), and person-year incidence rate was used to calculate the incidence rate of NAFLD in each group. Restricted cubic spline (RCS) curve was used to calculate the dose-response relation between continuous variables and outcome events; the Cox proportional hazards model was used to analyze hazard ratio ( HR ) and 95% confidence interval ( CI ) in each group and investigate the effect of ideal cardiovascular health metrics on the incidence rate of NAFLD. Results During the mean follow-up time of 5.58 years, a total of 15 265 cases of NAFLD were observed, and the incidence rate of NAFLD was 77.88/1000 person-year in the Q1 group, 61.33/1000 person-year in the Q2 group, 46.37/1000 person-year in the Q3 group, and 33.69/1000 person-year in the Q4 group. RCS results showed a non-linear relationship between CHS continuous variable and the risk of NAFLD ( P < 0.05). The multivariate Cox proportional risk model analysis showed that compared with the Q1 group in terms of the risk of NAFLD, the Q2, Q3, and Q4 groups had an HR of 0.78 (95% CI 0.74~0.81), 0.57 (95% CI 0.54~0.59), and 0.38 (95% CI 0.36~0.41), respectively, and similar results were observed in subjects stratified by sex and age. The analysis of each component showed that ideal body mass index ( HR =0.37, 95% CI : 0.36~0.39), ideal blood glucose ( HR =0.80, 95% CI : 0.77~0.84), ideal blood pressure ( HR =0.72, 95% CI : 0.69~0.75), ideal cholesterol ( HR =0.86, 95% CI : 0.83~0.89), and ideal diet ( HR =0.94, 95% CI : 0.90~0.99) were protective factors against NAFLD. Conclusion Ideal cardiovascular health metrics are protective factors against NAFLD, and maintaining a healthy lifestyle may help to prevent the onset of NAFLD.