Background:Pathological angiogenesis and blood–brain barrier damage may play an important role in Alzheimer's disease(AD).ACE2 is mainly expressed on the surface of endothelial cells in brain.Recent studies have ...Background:Pathological angiogenesis and blood–brain barrier damage may play an important role in Alzheimer's disease(AD).ACE2 is mainly expressed on the surface of endothelial cells in brain.Recent studies have shown that the expression of ACE2 in AD is reduced,but its role in AD is still unclear.Method:We induced AD damage in endothelial cells using Aβ25-35 and overexpressed ACE2 in bEend.3 cells through lentiviral transfection.We detected the effect of Aβ25-35 on cell viability using the CCK-8 assay and examined the effect of overexpressing ACE2 on angiogenesis using an angiogenesis assay.We used western blot and cell immunofluorescence to detect changes in the expression of the VEGF/VEGFR2 pathway,tight junction protein,and NF-κB pathway.Results:Aβ25-35 treatment significantly decreased the expression of ACE2 and reduced cell viability.ACE2 overexpression(1)reduced the number of branches and junctions in tube formation,(2)inhibited the activation of the VEGF/VEGFR2 pathway induced by Aβ25-35,(3)increased the expression of TJPs,including ZO-1 and claudin-5,and(4)restored Aβ25-35-induced activation of the NF-κB pathway.Conclusion:Overexpression of ACE2 can improve pathological angiogenesis and blood–brain barrier damage in AD models in vitro by inhibiting NF-κB/VEGF/VEGFR2 pathway activity.ACE2 may therefore represent a therapeutic target for endothelial cell dysfunction in AD.展开更多
The lotus(Nelumbo nucifera Gaertn.)is an aquatic plant that grows in shallow water and has long been cultivated in South China.It can improve the incomes of farmers and plays an important role in alleviating poverty i...The lotus(Nelumbo nucifera Gaertn.)is an aquatic plant that grows in shallow water and has long been cultivated in South China.It can improve the incomes of farmers and plays an important role in alleviating poverty in rural China.However,a modern method is required to accurately estimate the area of lotus fields.Lotus has spectral characteristics similar to those of rice,grassland,and shrubs.The features surrounding areas where it is grown are complex,small,and fragmented.Few studies have examined the remote sensing extraction of lotus fields,and automatic extraction and mapping are still challenging methods.Here,we compared the spectral characteristics of lotus fields and other ground objects and devised a remote sensing method for the rapid extraction of lotus fields.Using this method,the extraction accuracy of lotus was 96.3%.The Kappa coefficient was 0.926,which is higher than those of the unsupervised K-means classification,Mahalanobis distance,and support vector machine supervised classification,and demonstrates the potential of this method for extracting and mapping lotus fields by remote sensing.展开更多
Land use/coverage change(LUCC)exerts a profound influence on global carbon emission through changing structure and functions of ecosystem.Taking Nanchang City as an example,this study determined organic carbon emissio...Land use/coverage change(LUCC)exerts a profound influence on global carbon emission through changing structure and functions of ecosystem.Taking Nanchang City as an example,this study determined organic carbon emission of land ecosystem by ecosystem type method.In 2005,total carbon emission of Nanchang City was 4.826 2 Tg.In 2010,it became 5.535 9 Tg,showing a growth trend of carbon emission from land use change.The carbon emission of cropland and grassland decreased in 2005-2010,that of garden land and construction land had increase,and carbon absorption function of water land and other unused land was weakened.Due to difference of land use structure,the carbon emission of Nanchang City is varied.In 2005-2010,the rank of carbon emission from high to low is as follows:Nanchang County,Xinjian County,Jinxian County and Qingshanhu District.In combination with land use change and development plan of Nanchang City,Nanchang City should take carbon emission reduction measures,including conceding the land to forestry,returning the land to water,limiting excessive expansion of construction land,optimizing distribution of urban land use,flexibly regulating land supply policies,and establishing carbon trading legal system,to reach the objective of combining land use plan with ecological construction.展开更多
The rejuvenation of non-geostationary orbit(NGSO)satellite communication holds the promise of seamless and ubiquitous broadband access from the space.However,the NGSO constellations must share the scarce radio spectru...The rejuvenation of non-geostationary orbit(NGSO)satellite communication holds the promise of seamless and ubiquitous broadband access from the space.However,the NGSO constellations must share the scarce radio spectrum resources with geostationary orbit(GSO)satellite systems,which results in dynamically changing and unevenly distributed interference to GSO systems.In this context,the ultra-large-scale NGSO constellation incurs a more complicated interference environment with GSO systems,which raises urgent demands on inter-system interference evaluation.In this case,we investigate the inter-system downlink interference from a NGSO satellite mega-constellation to a GSO earth station.Specifically,we consider the scenario where the NGSO and GSO earth stations are co-located,and apply a novel visibility analysis method in the interference modeling to reduce computation redundancy.The interference evaluation is then performed through comprehensive simulations,in which the Starlink constellation with more than 4000 satellites is examined for the first time.The simulation results demonstrate various states of interference on the GSO earth station at different deployment locations.It reveals that the number of visible satellites could influence the angle between the main lobe directions of NGSO satellites and the GSO earth station antenna,which further affects the interference level.展开更多
基金Peking Union Medical CollegeCAMS initiative for Innovative Medicine of ChinaGrant/Award Number:2021-I2M-1-034
文摘Background:Pathological angiogenesis and blood–brain barrier damage may play an important role in Alzheimer's disease(AD).ACE2 is mainly expressed on the surface of endothelial cells in brain.Recent studies have shown that the expression of ACE2 in AD is reduced,but its role in AD is still unclear.Method:We induced AD damage in endothelial cells using Aβ25-35 and overexpressed ACE2 in bEend.3 cells through lentiviral transfection.We detected the effect of Aβ25-35 on cell viability using the CCK-8 assay and examined the effect of overexpressing ACE2 on angiogenesis using an angiogenesis assay.We used western blot and cell immunofluorescence to detect changes in the expression of the VEGF/VEGFR2 pathway,tight junction protein,and NF-κB pathway.Results:Aβ25-35 treatment significantly decreased the expression of ACE2 and reduced cell viability.ACE2 overexpression(1)reduced the number of branches and junctions in tube formation,(2)inhibited the activation of the VEGF/VEGFR2 pathway induced by Aβ25-35,(3)increased the expression of TJPs,including ZO-1 and claudin-5,and(4)restored Aβ25-35-induced activation of the NF-κB pathway.Conclusion:Overexpression of ACE2 can improve pathological angiogenesis and blood–brain barrier damage in AD models in vitro by inhibiting NF-κB/VEGF/VEGFR2 pathway activity.ACE2 may therefore represent a therapeutic target for endothelial cell dysfunction in AD.
基金the National Natural Science Foundation of China under Grants 31660140 and 31560150the Jiangxi Province 13th Five-Year Social Science Planning Project under Grant 17YJ11the Humanities and Social Sciences Planning Project of Colleges and Universities in Jiangxi Province under Grant GL17113.
文摘The lotus(Nelumbo nucifera Gaertn.)is an aquatic plant that grows in shallow water and has long been cultivated in South China.It can improve the incomes of farmers and plays an important role in alleviating poverty in rural China.However,a modern method is required to accurately estimate the area of lotus fields.Lotus has spectral characteristics similar to those of rice,grassland,and shrubs.The features surrounding areas where it is grown are complex,small,and fragmented.Few studies have examined the remote sensing extraction of lotus fields,and automatic extraction and mapping are still challenging methods.Here,we compared the spectral characteristics of lotus fields and other ground objects and devised a remote sensing method for the rapid extraction of lotus fields.Using this method,the extraction accuracy of lotus was 96.3%.The Kappa coefficient was 0.926,which is higher than those of the unsupervised K-means classification,Mahalanobis distance,and support vector machine supervised classification,and demonstrates the potential of this method for extracting and mapping lotus fields by remote sensing.
基金Supported by Project of National Natural Science Foundation(40861029)Social Science Research "12th Five-Year Plan" Project of Jiangxi Province(11YJ12 and 11Y13)+2 种基金Scientific and Technological Project of Jiangxi Provincial Department of Education(GJJ12218)Soft Science Project of Jiangxi Province(20111BAA10010)Humanity and Social Science Project of Colleges and Universities in Jiangxi Province(GL1030)
文摘Land use/coverage change(LUCC)exerts a profound influence on global carbon emission through changing structure and functions of ecosystem.Taking Nanchang City as an example,this study determined organic carbon emission of land ecosystem by ecosystem type method.In 2005,total carbon emission of Nanchang City was 4.826 2 Tg.In 2010,it became 5.535 9 Tg,showing a growth trend of carbon emission from land use change.The carbon emission of cropland and grassland decreased in 2005-2010,that of garden land and construction land had increase,and carbon absorption function of water land and other unused land was weakened.Due to difference of land use structure,the carbon emission of Nanchang City is varied.In 2005-2010,the rank of carbon emission from high to low is as follows:Nanchang County,Xinjian County,Jinxian County and Qingshanhu District.In combination with land use change and development plan of Nanchang City,Nanchang City should take carbon emission reduction measures,including conceding the land to forestry,returning the land to water,limiting excessive expansion of construction land,optimizing distribution of urban land use,flexibly regulating land supply policies,and establishing carbon trading legal system,to reach the objective of combining land use plan with ecological construction.
基金the Beijing Natural Science Foundation.L222003the National Key Research and Development Program.2020YFB1806100。
文摘The rejuvenation of non-geostationary orbit(NGSO)satellite communication holds the promise of seamless and ubiquitous broadband access from the space.However,the NGSO constellations must share the scarce radio spectrum resources with geostationary orbit(GSO)satellite systems,which results in dynamically changing and unevenly distributed interference to GSO systems.In this context,the ultra-large-scale NGSO constellation incurs a more complicated interference environment with GSO systems,which raises urgent demands on inter-system interference evaluation.In this case,we investigate the inter-system downlink interference from a NGSO satellite mega-constellation to a GSO earth station.Specifically,we consider the scenario where the NGSO and GSO earth stations are co-located,and apply a novel visibility analysis method in the interference modeling to reduce computation redundancy.The interference evaluation is then performed through comprehensive simulations,in which the Starlink constellation with more than 4000 satellites is examined for the first time.The simulation results demonstrate various states of interference on the GSO earth station at different deployment locations.It reveals that the number of visible satellites could influence the angle between the main lobe directions of NGSO satellites and the GSO earth station antenna,which further affects the interference level.
