BACKGROUND: Trabecular metal has been reported to provide enough physiologic support for new bone formation, to induce bone ingrowth and osseointegration so as to achieve the biological synosteosis; therefore, it is available for improving the initial and second stability of the dental implant.OBJECTIVE: To explore the stress distributional differences between porous tantalum trabecular metal (PTTM) dental implant and conventional titanium (TI) dental implant in the zone of mandibular premolar using three-dimensional finite element analysis.METHODS: Three-dimensional finite element models emulating PTTM and TI dental implants were established using Mimics16.0 and CATIA in the zone of mandibular premolar with three types of bone (II, III, IV). Then 100 N force was applied on the abutment at a 45° angle to the vertical axis of the implants in software of MSC Patran2010 and Nastran2010, then the representative von Mises stress nodes were calculated and sampled randomly, and finally the von Mises stress distributional differences between two types of implants were analyzed using SPSS 20.0 statistical software.RESULTS AND CONCLUSION: (1) The Von Mises stresses around the two types of implants both focused on the interface of the cortical bone-abutment-implant region, and the stress was relatively less for the corresponding trabecular bone. (2) If the bone quality was similar, the average von Mises stress of PTTM was higher than that of TI dental implants, but there was no significant difference (P > 0.05). As the bone density lowered (II-IV), the average Von Mises stresses were both increased, and the increasing rate of PTTM was higher than that of TI in bone of II-III, and was lower than that of TI in bone of III-IV. In this experiment, there were no significant stress distributional differences between PTTM and TI dental implant. However, with the bone density reduction, the increasing rate of average Von Mises stress for PTTM was lowered than that for TI dental implants in bone of III-IV, which suggests that PTTM dental implant may be more beneficial for the primary and secondary stability in osteoporosis patients undergoing dental implantation.

Gut microbiota participates in numerous physiological and metabolic processes in the human body,directly affecting human health.The imbalance of gut microbiota may lead to many diseases.This article reviews the types of gut microbiota,the impact of gut microbiota on different populations,and the relationship between gut microbiota abnormalities and diseases,in order to better explain the important role of gut microbiota in human health and diseases,and provide the theoretical basis for further understanding the relationship between gut microbiota and human health.

Myocardial infarction （MI） refers to an acute clinical syndrome of myocardial necrosis due to persistent ischemia and hypoxia， resulting from the sharp reduction or interruption of coronary blood flow. Nuclear factor κB （NF-κB） is the key factor in inducing inflammatory response， and it is involved in the production of pro-inflammatory factors and myocardial cell apoptosis. This article systematically describes the molecular regulation mechanism of the NF-κB signaling pathway in MI， and reviews the related research on the prevention and treatment of MI through the regulation of this signaling pathway by active ingredients and compound formulas from traditional Chinese medicine （TCM）. It has been found that active ingredients from TCM， such as ginsenoside Rg3， baicalein， curcumin， tanshinone ⅡA， gambogic acid， as well as compound formulas， including Qili qiangxin capsules， Yiqi huoxue decoction， Lingbao huxin dan， Danhong injection， Baoyuan decoction combined with Taohong siwu decoction， can improve myocardial fibrosis， alleviate inflammatory responses， and inhibit cardiomyocyte apoptosis by suppressing the NF-κB signaling pathway. Thereby， they achieve the goal of preventing and treating MI.

Objective: To investigate the positive rate for 2019-nCoV tests and co-infections in Wuhan district. Methods: A total of 8 274 cases in Wuhan were enrolled in this cross-sectional study during January 20 to February 9, 2020, and were tested for 2019-nCoV using fluorescence quantitative PCR. Both respiratory tract samples (nasopharynx, oropharynx, sputum and alveolar lavage fluid) and non-respiratory tract samples (urine, feces, anal swabs, blood and conjunctival sac swabs) were collected. If both orf1ab and N genes are positive, they are classified as nucleic acid test positive group; if both orf1ab and N genes are negative, they are classified as negative group; if single gene target is positive, they are classified as suspicious group. Individuals were divided into male group and female group according to sex. At the same time, 316 patients were tested for 13 respiratory pathogens by multiplex PCR. Results: Among the 8 274 subjects, 2 745 (33.2%) were 2019-nCoV infected; 5 277 (63.8%) subjects showed negative results in the 2019-nCoV nucleic acid test; and 252 cases (3.05%) was not definitive (inconclusive result). The age of cases with COVID-19 patients and inconclusive cases was significantly higher than that of cases without 2019-nCoV infection (40 vs 56, t=27.569, P<0.001; 52 vs 56, t=6.774, P<0.001). The positive rate of 13 respiratory pathogens multiple tests was significantly lower in 104 subjects who were positive for 2019-nCoV compared with those in subjects who were negative for 2019-nCoV test (5.77% vs 18.39%, χ²=24.105, P=0.003). Four types of respiratory tract samples and five types of non-respiratory tract samples were found to be positive for 2019-nCoV nucleic acid test. Conclusion The 2019-nCoV nucleic acid positive rate in male is higher than in female. Co-infections should be pay close attention in COVID-19 patients. 2019-nCoV nucleic acid can be detected in non-respiratory tract samples.