Objective:Against the backdrop of population aging and air pollution,this study examined the re-gional distribution of depressive symptoms among middle-aged and elderly people in China and explores the influ-ence of patrticulate matter 2.5(PM2.5)concentration on these symptoms.This study examined the regional distri-bution of depressive symptoms in middle-aged and elderly people in China and explores the influence of PM2.5 concentration and related factors on these symptoms.Methods:Middle-aged and elderly people aged 45 years and above in CHARLS database in 2013,2015 and 2018 were selected as research objects,and the Center for Epidemio-logic Studies Depression Scale(CESD-10)to obtain the detection rate of depressive symptoms.The PM2.5 concen-tration data were derived from the annual data of the China Environmental Monitoring Station.t-test,x2 test and DID model were used to analyze the related factors of depressive symptoms.Stata17.0 and Arc GIS10.8 were used for spatial autocorrelation analysis to explore the regional distribution and relationship of depressive symptoms in mid-dle-aged and elderly people in China.Results:From east to west,the detection rate of depressive symptoms in mid-dle-aged and elderly people in China showed an increasing trend.The regional distribution of PM2.5 mainly showed that the central region was higher than the northern and southern regions and the western region(except Xinjiang)was higher than the eastern region.Conclusion:Both the PM2.5 concentration and depression symptoms exhibit spatial clustering across China.PM2.5 has a negative impact on depression symptoms in middle-aged and elderly people,with other related factors including gender,age,education level,marital status,living area,smoking status.

Objective:Against the backdrop of population aging and air pollution,this study examined the re-gional distribution of depressive symptoms among middle-aged and elderly people in China and explores the influ-ence of patrticulate matter 2.5(PM2.5)concentration on these symptoms.This study examined the regional distri-bution of depressive symptoms in middle-aged and elderly people in China and explores the influence of PM2.5 concentration and related factors on these symptoms.Methods:Middle-aged and elderly people aged 45 years and above in CHARLS database in 2013,2015 and 2018 were selected as research objects,and the Center for Epidemio-logic Studies Depression Scale(CESD-10)to obtain the detection rate of depressive symptoms.The PM2.5 concen-tration data were derived from the annual data of the China Environmental Monitoring Station.t-test,x2 test and DID model were used to analyze the related factors of depressive symptoms.Stata17.0 and Arc GIS10.8 were used for spatial autocorrelation analysis to explore the regional distribution and relationship of depressive symptoms in mid-dle-aged and elderly people in China.Results:From east to west,the detection rate of depressive symptoms in mid-dle-aged and elderly people in China showed an increasing trend.The regional distribution of PM2.5 mainly showed that the central region was higher than the northern and southern regions and the western region(except Xinjiang)was higher than the eastern region.Conclusion:Both the PM2.5 concentration and depression symptoms exhibit spatial clustering across China.PM2.5 has a negative impact on depression symptoms in middle-aged and elderly people,with other related factors including gender,age,education level,marital status,living area,smoking status.

BACKGROUND: In the process of bone defect healing, the use of biological materials loaded with drugs for local defect intervention can accelerate the repair of the defect, which provides a new method for the local treatment of bone defects. OBJECTIVE: To introduce the local application of bone tissue engineering scaffolds loaded with bisphosphonates in bone defect repair and to summarize the effects of bone tissue engineering scaffolds as a drug delivery system on the bone defect healing. METHODS: The authors retrieved PubMed, Web of Science, Springerlink, Medline, WanFang and CNKI databases with "bisphosphonates, alendronate, zoledronate, bone defect, bone tissue engineering" as key words for relevant articles published from 2006 to 2018. Initially, 235 articles were retrieved, and finally 70 articles were selected for further analysis. RESULTS AND CONCLUSION: Bisphosphonate drug is an effective inhibitor of osteoclast dissolution. It can form a drug sustained release system on the local defect by being loaded to composite scaffolds, promote the formation of new bone and accelerate the healing of the defect. For the drug delivery system of bisphosphonates, suitable scaffold materials are crucial to the osteogenic effect of composite scaffolds in the defect area. At present, the carrier materials used for bisphosphonate-loaded composite scaffolds are mainly divided into organic materials and inorganic materials. Most polymeric organic materials can directly load bisphosphonates to form good drug sustained release in the local area and obviously exert their pro-osteogenic effects, while natural materials and most inorganic materials are often combined with other materials to form composite materials as carriers to optimize the carrier performance. Most studies have also confirmed that these composite materials loaded with bisphosphonates in the defect area exert osteogenic effect in the defect area.