为解决氙(Xe)的九种稳定同位素质量差异大(约9.6%),质谱探测器接收难的问题,利用Helix MC Plus静态气体质谱仪,建立一种测量Xe全部稳定同位素丰度比的高精度质谱分析方法,快速、准确获得Xe的全部稳定同位素丰度。首先对混合气体样品中...为解决氙(Xe)的九种稳定同位素质量差异大(约9.6%),质谱探测器接收难的问题,利用Helix MC Plus静态气体质谱仪,建立一种测量Xe全部稳定同位素丰度比的高精度质谱分析方法,快速、准确获得Xe的全部稳定同位素丰度。首先对混合气体样品中的Xe进行提取分离与纯化等条件实验,减小其他惰性气体及活性组分对Xe同位素分析测量的影响,再使用跳峰和多接收两种方式相结合的测量方法,实现在进样量极小时,基于Helix MC Plus型静态气体质谱仪的Xe全部稳定同位素的高精度测量,并利用天然丰度Xe标准气体对配制的混合气体样品测量结果进行线性校正。结果表明,在进样量约1.12×10^(-12)mol条件下,法拉第杯测量129 Xe/^(132)Xe、^(130)Xe/^(132)Xe、^(131)Xe/^(132)Xe、^(134)Xe/^(132)Xe、^(136)Xe/^(132)Xe丰度比的相对标准偏差≤0.24%,对于使用计数法测量124 Xe/^(132)Xe、126 Xe/^(132)Xe丰度比的相对标准偏差分别为0.22%和0.39%。本方法稳定性好、精度高,可以实现痕量Xe稳定同位素的丰度比质谱分析测试。展开更多
AIM:To investigate the effects of on ocular surface microbiota in patients who received intravitreal injections.METHODS:Samples of ocular surface microbiota were obtained from 41 eyes of 41 patients who visited the De...AIM:To investigate the effects of on ocular surface microbiota in patients who received intravitreal injections.METHODS:Samples of ocular surface microbiota were obtained from 41 eyes of 41 patients who visited the Department of Ophthalmology.Patients were separated for three groups.Group A did not receive perioperative managements or intravitreal injection.Group B1 received only once and B2 received more than twice.In operating room,the samples were collected on the ocular surface.Operating taxonomic units(OTUs) clustering and alpha/beta diversity analysis was performed.The microbial 16S rRNA from samples were analyzed using the Hi Seq 2500 platform.RESULTS:Alpha diversity did not differ in each group,and beta diversity differed in the B2 group.Beta diversity showed a significant difference between Group A and B2(P=0.048).With the perioperative managements before intravitreal injection,the composition and relative abundance were altered.Top 10 microbiota on phylum and genus level,and then microbiota notably changed at genus level were listed.Gram-negative bacteria were varied more.Furthermore,Proteus was not found in Groups A and B1,but it was appeared after the patients received perioperative management and intravitreal injections in Group B2.CONCLUSION:With the perioperative managements,the balance of microbiota on the ocular surface is destroyed,and relative composition and abundance of microbiota on the ocular surface is obviously altered.The clinical doctors should pay more attention on the consequence of perioperative managements before intravitreal injection.展开更多
The mixed lineage kinase domain-like(MLKL)protein is a key factor in tumor necrosis factor-induced necroptosis.Recent studies on necroptosis execution revealed a commitment role of MLKL in membrane disruption.However,...The mixed lineage kinase domain-like(MLKL)protein is a key factor in tumor necrosis factor-induced necroptosis.Recent studies on necroptosis execution revealed a commitment role of MLKL in membrane disruption.However,our knowledge of how MLKL functions on membrane remains very limited.Here we demonstrate that MLKL forms cation channels that are permeable preferential y to Mg2+rather than Ca2+in the presence of Na+and K+.Moreover,the N-terminal domain containing six helices(H1-H6)is sufficient to form channels.Using the substituted cysteine accessibility method,we further determine that helix H1,H2,H3,H5 and H6 are transmembrane segments,while H4 is located in the cytoplasm.Finally,MLKL-induced membrane depolarization and cell death exhibit a positive correlation to its channel activity.The Mg2+-preferred permeability and five transmembrane segment topology distinguish MLKL from previously identified Mg2+-permeable channels and thus establish MLKL as a novel class of cation channels.展开更多
文摘为解决氙(Xe)的九种稳定同位素质量差异大(约9.6%),质谱探测器接收难的问题,利用Helix MC Plus静态气体质谱仪,建立一种测量Xe全部稳定同位素丰度比的高精度质谱分析方法,快速、准确获得Xe的全部稳定同位素丰度。首先对混合气体样品中的Xe进行提取分离与纯化等条件实验,减小其他惰性气体及活性组分对Xe同位素分析测量的影响,再使用跳峰和多接收两种方式相结合的测量方法,实现在进样量极小时,基于Helix MC Plus型静态气体质谱仪的Xe全部稳定同位素的高精度测量,并利用天然丰度Xe标准气体对配制的混合气体样品测量结果进行线性校正。结果表明,在进样量约1.12×10^(-12)mol条件下,法拉第杯测量129 Xe/^(132)Xe、^(130)Xe/^(132)Xe、^(131)Xe/^(132)Xe、^(134)Xe/^(132)Xe、^(136)Xe/^(132)Xe丰度比的相对标准偏差≤0.24%,对于使用计数法测量124 Xe/^(132)Xe、126 Xe/^(132)Xe丰度比的相对标准偏差分别为0.22%和0.39%。本方法稳定性好、精度高,可以实现痕量Xe稳定同位素的丰度比质谱分析测试。
基金Supported by Key Research and Development Program of Shaanxi Province in China (No.2017SF-028)the Natural Science Foundation of Shaanxi Province (No.2019JQ-953)the Fundamental Research Funds for the Central Universities sponsored by Xi’an Jiaotong University (No.11913291000038/11913200000213)。
文摘AIM:To investigate the effects of on ocular surface microbiota in patients who received intravitreal injections.METHODS:Samples of ocular surface microbiota were obtained from 41 eyes of 41 patients who visited the Department of Ophthalmology.Patients were separated for three groups.Group A did not receive perioperative managements or intravitreal injection.Group B1 received only once and B2 received more than twice.In operating room,the samples were collected on the ocular surface.Operating taxonomic units(OTUs) clustering and alpha/beta diversity analysis was performed.The microbial 16S rRNA from samples were analyzed using the Hi Seq 2500 platform.RESULTS:Alpha diversity did not differ in each group,and beta diversity differed in the B2 group.Beta diversity showed a significant difference between Group A and B2(P=0.048).With the perioperative managements before intravitreal injection,the composition and relative abundance were altered.Top 10 microbiota on phylum and genus level,and then microbiota notably changed at genus level were listed.Gram-negative bacteria were varied more.Furthermore,Proteus was not found in Groups A and B1,but it was appeared after the patients received perioperative management and intravitreal injections in Group B2.CONCLUSION:With the perioperative managements,the balance of microbiota on the ocular surface is destroyed,and relative composition and abundance of microbiota on the ocular surface is obviously altered.The clinical doctors should pay more attention on the consequence of perioperative managements before intravitreal injection.
文摘The mixed lineage kinase domain-like(MLKL)protein is a key factor in tumor necrosis factor-induced necroptosis.Recent studies on necroptosis execution revealed a commitment role of MLKL in membrane disruption.However,our knowledge of how MLKL functions on membrane remains very limited.Here we demonstrate that MLKL forms cation channels that are permeable preferential y to Mg2+rather than Ca2+in the presence of Na+and K+.Moreover,the N-terminal domain containing six helices(H1-H6)is sufficient to form channels.Using the substituted cysteine accessibility method,we further determine that helix H1,H2,H3,H5 and H6 are transmembrane segments,while H4 is located in the cytoplasm.Finally,MLKL-induced membrane depolarization and cell death exhibit a positive correlation to its channel activity.The Mg2+-preferred permeability and five transmembrane segment topology distinguish MLKL from previously identified Mg2+-permeable channels and thus establish MLKL as a novel class of cation channels.
