Debates regarding the specific effects of general anesthesia on developing brains have persisted for over 30 years.A consensus has been reached that prolonged,repeated,high-dose exposure to anesthetics is associated w...Debates regarding the specific effects of general anesthesia on developing brains have persisted for over 30 years.A consensus has been reached that prolonged,repeated,high-dose exposure to anesthetics is associated with a higher incidence of deficits in behavior and executive function,while single exposure has a relatively minor effect on long-term neurological function.In this review,we summarize the dose-dependent neuroprotective or neurotoxic effects of gamma-aminobutyric acid type A receptor agonists,a representative group of sedatives,on developing brains or central nervous system diseases.Most preclinical research indicates that anesthetics have neurotoxic effects on the developing brain through various signal pathways.However,recent studies on low-dose anesthetics suggest that they may promote neurodevelopment during this critical period.These findings are incomprehensible for the general“dose-effect”principles of pharmacological research,which has attracted researchers'interest and led to the following questions:What is the threshold for the dual effects exerted by anesthetics such as propofol and sevoflurane on the developing brain?To what extent can their protective effects be maximized?What are the underlying mechanisms involved in these effects?Consequently,this issue has essentially become a“mathematical problem.”After summarizing the dose-dependent effects of gamma-aminobutyric acid type A receptor agonist sedatives in both the developing brain and the brains of patients with central nervous system diseases,we believe that all such anesthetics exhibit specific threshold effects unique to each drug.These effects range from neuroprotection to neurotoxicity,depending on different brain functional states.However,the exact values of the specific thresholds for different drugs in various brain states,as well as the underlying mechanisms explaining why these thresholds exist,remain unclear.Further in-depth exploration of these issues could significantly enhance the therapeutic translational value of these anesthetics.展开更多
The objective of this research was to acquire a raindrop size distribution(DSDs)retrieved from C-band polarimetric radar observations scheme for the first time in south China.An observation period of the precipitation...The objective of this research was to acquire a raindrop size distribution(DSDs)retrieved from C-band polarimetric radar observations scheme for the first time in south China.An observation period of the precipitation process was selected,and the shape-slope(μ-Λ)relationship of this region was statistically analyzed using the raindrop sample observations from the two-dimensional video disdrometer(2DVD)at Xinfeng Station,Guangdong Province.Simulated data of the C-band polarimetric radar reflectivity ZHHand differential reflectivity ZDRwere obtained through scattering simulation.The simulation data were combined with DSD fitting to determine the ZDR-Λand log10(ZHH/N0)-Λrelationships.Using Xinfeng C-band polarimetric radar observations ZDRand ZHH,the raindrop Gamma size distribution parametersμ,Λ,and N0were retrieved.A scheme for using C-band polarimetric radar to retrieve the DSDs was developed.This research revealed that during precipitation process,the DSDs obtained using the C-band polarimetric radar retrieval scheme are similar to the 2DVD observations,the precipitation characteristics of rainfall intensity(R),mass-weighted mean diameter(Dm)and intercept parameter(Nw)with time obtained by radar retrieval are basically consistent with the observational results of the 2DVD.This scheme establishes the relationship between the observations of the C-band polarimetric radar and the physical quantities of the numerical model.This method not only can test the prediction of the model data assimilation system on the convective scale and determine error sources,but also can improve the microphysical precipitation processes analysis and radar quantitative precipitation estimation.The present research will facilitate radar data assimilation in the future.展开更多
随着社会经济的发展,传统的“按项目付费”的支付方式不足以有效地控制医疗费用的不合理增长,社会需要新的支付方式来迫使医疗机构加强成本控制,优化医疗费用结构^[1]。在这样的背景下,疾病诊断相关分组(diagnosis related group,DRG)...随着社会经济的发展,传统的“按项目付费”的支付方式不足以有效地控制医疗费用的不合理增长,社会需要新的支付方式来迫使医疗机构加强成本控制,优化医疗费用结构^[1]。在这样的背景下,疾病诊断相关分组(diagnosis related group,DRG)付费方式应运而生。展开更多
文摘Debates regarding the specific effects of general anesthesia on developing brains have persisted for over 30 years.A consensus has been reached that prolonged,repeated,high-dose exposure to anesthetics is associated with a higher incidence of deficits in behavior and executive function,while single exposure has a relatively minor effect on long-term neurological function.In this review,we summarize the dose-dependent neuroprotective or neurotoxic effects of gamma-aminobutyric acid type A receptor agonists,a representative group of sedatives,on developing brains or central nervous system diseases.Most preclinical research indicates that anesthetics have neurotoxic effects on the developing brain through various signal pathways.However,recent studies on low-dose anesthetics suggest that they may promote neurodevelopment during this critical period.These findings are incomprehensible for the general“dose-effect”principles of pharmacological research,which has attracted researchers'interest and led to the following questions:What is the threshold for the dual effects exerted by anesthetics such as propofol and sevoflurane on the developing brain?To what extent can their protective effects be maximized?What are the underlying mechanisms involved in these effects?Consequently,this issue has essentially become a“mathematical problem.”After summarizing the dose-dependent effects of gamma-aminobutyric acid type A receptor agonist sedatives in both the developing brain and the brains of patients with central nervous system diseases,we believe that all such anesthetics exhibit specific threshold effects unique to each drug.These effects range from neuroprotection to neurotoxicity,depending on different brain functional states.However,the exact values of the specific thresholds for different drugs in various brain states,as well as the underlying mechanisms explaining why these thresholds exist,remain unclear.Further in-depth exploration of these issues could significantly enhance the therapeutic translational value of these anesthetics.
基金National Key R&D Program of China(2018YFC1507401)Science and Technology Planning Project of Guangdong Province(2017B020244002)+1 种基金National Natural Science Foundation of China(41975138,41705020)Natural Science Foundation of Guangdong Province(2019A1515010814)。
文摘The objective of this research was to acquire a raindrop size distribution(DSDs)retrieved from C-band polarimetric radar observations scheme for the first time in south China.An observation period of the precipitation process was selected,and the shape-slope(μ-Λ)relationship of this region was statistically analyzed using the raindrop sample observations from the two-dimensional video disdrometer(2DVD)at Xinfeng Station,Guangdong Province.Simulated data of the C-band polarimetric radar reflectivity ZHHand differential reflectivity ZDRwere obtained through scattering simulation.The simulation data were combined with DSD fitting to determine the ZDR-Λand log10(ZHH/N0)-Λrelationships.Using Xinfeng C-band polarimetric radar observations ZDRand ZHH,the raindrop Gamma size distribution parametersμ,Λ,and N0were retrieved.A scheme for using C-band polarimetric radar to retrieve the DSDs was developed.This research revealed that during precipitation process,the DSDs obtained using the C-band polarimetric radar retrieval scheme are similar to the 2DVD observations,the precipitation characteristics of rainfall intensity(R),mass-weighted mean diameter(Dm)and intercept parameter(Nw)with time obtained by radar retrieval are basically consistent with the observational results of the 2DVD.This scheme establishes the relationship between the observations of the C-band polarimetric radar and the physical quantities of the numerical model.This method not only can test the prediction of the model data assimilation system on the convective scale and determine error sources,but also can improve the microphysical precipitation processes analysis and radar quantitative precipitation estimation.The present research will facilitate radar data assimilation in the future.
