Objective To provide reference for improving drug procurement with target quantity in China.Methods Documents on drug centralized procurement such as the “Guidance on Drug Procurement with Target Quantity for 4+7 Cit...Objective To provide reference for improving drug procurement with target quantity in China.Methods Documents on drug centralized procurement such as the “Guidance on Drug Procurement with Target Quantity for 4+7 Cities” issued by National Healthcare Security Administration in November 2018 and “Notice on the National Organization of the Pilot Program for Drug Centralized Procurement and Use of Bidding Drugs” issued by the State Council were studied to summarize the mode and result of drug procurement with target quantity.Results and Conclusion Drug procurement with target quantity led by National Healthcare Security Administration solved some problems in the previous centralized drug procurement.For instance,quantity could not determine drug price,and medical institutions didn’t pay to pharmaceutical companies on time.However,this new mode may also arouse new problems such as procurement monopoly,drug shortage,drug quality and inhibition of innovation.展开更多
【目的】细菌机械敏感性离子通道MscS能够在细菌周围环境渗透压急剧降低时,打开并释放胞内内容物,平衡内外渗透压差,使细菌存活。鉴于其广泛分布在各种细菌中,而在哺乳动物中未发现其同源体,MscS被认为是一种新型抗生素靶点。MscS一个...【目的】细菌机械敏感性离子通道MscS能够在细菌周围环境渗透压急剧降低时,打开并释放胞内内容物,平衡内外渗透压差,使细菌存活。鉴于其广泛分布在各种细菌中,而在哺乳动物中未发现其同源体,MscS被认为是一种新型抗生素靶点。MscS一个独特的开放特征是具有失活特性,即在持续的机械刺激条件下,MscS从开放状态进入一种非离子通透的失活状态,从而避免因通道持续开放引起大量内容物流失导致细菌死亡。该研究的目的是鉴定影响MscS失活的关键氨基酸,为靶向Msc S的药物设计提供思路。【方法】采用分子克隆方法制备Msc S Cyto-helix(P166−I170)半胱氨酸突变体,利用巯基化合物MTSET^(+)结合半胱氨酸从而对其侧链基团进行修饰,并通过低渗刺激实验,检测表达MscS半胱氨酸突变体的大肠杆菌分别在无或有MTSET^(+)处理下,低渗刺激诱发通道开放后的存活率筛选显著影响通道功能的突变体。利用电生理膜片钳方法检测突变体在MTSET^(+)处理前后通道失活特性的变化,结合定点突变手段进一步探讨失活机制。【结果】MTSET^(+)处理导致表达半胱氨酸突变体G168C-MscS的大肠杆菌在低渗刺激后存活率极大降低;G168C-MscS在结合MTSET^(+)后失去失活特性,保持持续开放,是导致细菌胞内内容物大量流失并死亡的重要原因;酪氨酸突变G168Y-MscS、亮氨酸突变G168L-MscS和赖氨酸突变G168K-MscS的失活特性与野生型WT-MscS一致,而天冬氨酸突变G168D、缬氨酸突变G168V和异亮氨酸突变G168I的失活速率显著降低,尤其是G168I-MscS失去失活特性,表明MscS 168位点是影响通道失活的关键位点,并且通道失活特性与该位点氨基酸侧链基团的大小及电荷性质相关。【结论】G168位点甘氨酸是影响MscS通道失活的关键氨基酸。展开更多
文摘Objective To provide reference for improving drug procurement with target quantity in China.Methods Documents on drug centralized procurement such as the “Guidance on Drug Procurement with Target Quantity for 4+7 Cities” issued by National Healthcare Security Administration in November 2018 and “Notice on the National Organization of the Pilot Program for Drug Centralized Procurement and Use of Bidding Drugs” issued by the State Council were studied to summarize the mode and result of drug procurement with target quantity.Results and Conclusion Drug procurement with target quantity led by National Healthcare Security Administration solved some problems in the previous centralized drug procurement.For instance,quantity could not determine drug price,and medical institutions didn’t pay to pharmaceutical companies on time.However,this new mode may also arouse new problems such as procurement monopoly,drug shortage,drug quality and inhibition of innovation.
文摘【目的】细菌机械敏感性离子通道MscS能够在细菌周围环境渗透压急剧降低时,打开并释放胞内内容物,平衡内外渗透压差,使细菌存活。鉴于其广泛分布在各种细菌中,而在哺乳动物中未发现其同源体,MscS被认为是一种新型抗生素靶点。MscS一个独特的开放特征是具有失活特性,即在持续的机械刺激条件下,MscS从开放状态进入一种非离子通透的失活状态,从而避免因通道持续开放引起大量内容物流失导致细菌死亡。该研究的目的是鉴定影响MscS失活的关键氨基酸,为靶向Msc S的药物设计提供思路。【方法】采用分子克隆方法制备Msc S Cyto-helix(P166−I170)半胱氨酸突变体,利用巯基化合物MTSET^(+)结合半胱氨酸从而对其侧链基团进行修饰,并通过低渗刺激实验,检测表达MscS半胱氨酸突变体的大肠杆菌分别在无或有MTSET^(+)处理下,低渗刺激诱发通道开放后的存活率筛选显著影响通道功能的突变体。利用电生理膜片钳方法检测突变体在MTSET^(+)处理前后通道失活特性的变化,结合定点突变手段进一步探讨失活机制。【结果】MTSET^(+)处理导致表达半胱氨酸突变体G168C-MscS的大肠杆菌在低渗刺激后存活率极大降低;G168C-MscS在结合MTSET^(+)后失去失活特性,保持持续开放,是导致细菌胞内内容物大量流失并死亡的重要原因;酪氨酸突变G168Y-MscS、亮氨酸突变G168L-MscS和赖氨酸突变G168K-MscS的失活特性与野生型WT-MscS一致,而天冬氨酸突变G168D、缬氨酸突变G168V和异亮氨酸突变G168I的失活速率显著降低,尤其是G168I-MscS失去失活特性,表明MscS 168位点是影响通道失活的关键位点,并且通道失活特性与该位点氨基酸侧链基团的大小及电荷性质相关。【结论】G168位点甘氨酸是影响MscS通道失活的关键氨基酸。