BACKGROUND:Satellite cells are a specific population of adult stem cells contained in skeletal muscle that promote the regenerative reconstruction of injured skeletal muscle,but their specific mechanisms are not well established. OBJECTIVE:To review the regulatory role of satellite cells during skeletal muscle regeneration and the mechanism of interaction between satellite cells and their ecological niche signals,aiming to provide new research ideas and perspectives based on the summary of existing knowledge. METHODS:Web of Science,PubMed,CNKI,WanFang,and VIP databases were searched for literature published between January 2002 and June 2022.English search terms were"muscle,skeletal muscle,muscle injury,stem cells,satellite cells,muscle repair".Chinese search terms were"skeletal muscle,skeletal muscle regeneration,skeletal muscle reconstruction,satellite cells,ecological niche".The 66 included papers were organized and analyzed. RESULTS AND CONCLUSION:(1)Satellite cells exist in skeletal muscle and contribute to both the formation of new muscle fibers after injury and the effective growth of existing adult muscle fibers.(2)After the activation of quiescent satellite cells in satellite cells,the steps of satellite cell proliferation,differentiation and fusion to form muscle fibers during skeletal muscle regeneration are influenced by their intrinsic regulatory effects of different mechanisms.(3)Satellite cells can interact with myofibers,extracellular matrix,skeletal muscle junctions,fibroblast progenitor cells,immune cells and endothelial cells in the ecological niche signal to promote satellite cell activation,proliferation and differentiation to achieve effective skeletal muscle regeneration.(4)Possible breakthroughs in future research include:the division pattern of satellite cells in the body;the mechanisms regulating satellite cell transfer;the specific timing of satellite cell differentiation or self-renewal in vivo;and the interaction mechanisms between satellite cells and skeletal muscle junctions.(5)This review may provide some theoretical reference values for the field of injury reconstruction of skeletal muscle and its innovation.

Objective To analyze the epidemiological characteristics of human brucellosis in northern and southern areas of China,and to develop national strategies for brucellosis prevention and control.Methods Individual data on human brucellosis was collected from the National Notifiable Infectious Disease Reporting Information System to describe the situation of brucellosis in China during 2015-2016.Epidemiological features of the disease in northem and southern areas of China were analyzed.Results A total of 104 125 cases were reported in mainland China during 2015-2016,with an average incidence rate as 3.81/100 000.The overall incidence rate from the northem provinces was 7.77/100 000 in 2016,a 18.6％ decrease from 2015 (9.55/100 000),whereas the incidence rate in the southern provinces was 0.27/100 000 in 2016,with an increase of 28.6％ than 0.21/100 000 in 2015.90.0％ of the newly infected counties mainly distributed in southern China.As for the locations of reporting cases,most of them were in the same counties in the northern areas (52.3％) while most cases in the southern areas (59.6％) were imported from other counties.The median age of the cases was 48 (IQR:38-58) years,with male-to-female ratios as 2.7 ∶ 1 in the north and 2.2 ∶ 1 in the south.Majority of the cases were occupation-related,from both the northern (86.8％) and southern (62.7％) areas.Human brucellosis occurred every month throughout the year but with an obvious seasonal increase between March and July.Conclusions Different epidemiological features of human brucellosis appeared in both northern and southern areas of China.The disease was seen endemic in the northem and dispersal in the southem provinces.Appropriate strategies for brucellosis prevention and control should be developed,according to the different epidemiological characteristics in the northcm or southcm areas.