Smog chamber experiments were performed to investigate the composition of products formed from photooxidation of aromatic hydrocarbon ethylbenzene. Vacuum ultraviolet photoionization mass spectrometer and aerosol time...Smog chamber experiments were performed to investigate the composition of products formed from photooxidation of aromatic hydrocarbon ethylbenzene. Vacuum ultraviolet photoionization mass spectrometer and aerosol time-of-flight mass spectrometer were used to measure the products in the gas and particle phases in real-time. Experimental results demonstrated that ethylphenol, methylglyoxal, phenol, benzaldehyde, and 2-ethylfurane were the predominant photooxidation products in both the gas and particle phases. However, there were some differences between detected gas phase products and those of particle phase, for example, 2-ethylfurane, ethylglyoxylic acid, nitroethylbenzene, 3,4-dioxopentanal and ethyl-nitrophenol were only existing in the particle-phase. The possible reaction mechanisms leading to these products were also discussed and proposed.展开更多
The gas-phase organic compounds resulting from OH-initiated photooxidation of isoprene have been investigated on-line by VUV photoiortization mass spectrometry based on synchrotron radiation for the first time. The ph...The gas-phase organic compounds resulting from OH-initiated photooxidation of isoprene have been investigated on-line by VUV photoiortization mass spectrometry based on synchrotron radiation for the first time. The photoionization efficiency curves of the corresponding gaseous products as well as the chosen standards have been deduced by gating the interested peaks in the photoionization mass spectra while scanning the photon energy simultaneously, which permits the identification of the pivotal gaseous products of the photooxidation of isoprene, such as formaldehyde （10.84 eV）, formic acid （11.38 eV）, acetone （9.68 eV）, glyoxal （9.84 eV）, acetic acid （10.75 eV）, methacrolein （9.91 eV）, and methyl vinyl ketone （9.66 eV）. Proposed reaction mechanisms leading to the formation of these key products were discussed, which were completely consistent with the previous works of different groups. The capability of synchrotron radiation photoionization mass spectrometry to directly identify the chemical composition of the gaseous products in a simulation chamber has been demonstrated, and its potential application in related studies of atmospheric oxidation of ambient volatile organic compounds is anticipated.展开更多
Background Astrocytes regulate blood-brain barrier(BBB)integrity,whereas subarachnoid haemorrhage(SAH)results in astrocyte dysregulation and BBB disruption.Here,we explored the involvement of tissue inhibitor of matri...Background Astrocytes regulate blood-brain barrier(BBB)integrity,whereas subarachnoid haemorrhage(SAH)results in astrocyte dysregulation and BBB disruption.Here,we explored the involvement of tissue inhibitor of matrix metalloprotease-1(TIMP1)in astrocyte-mediated BBB protection during SAH,along with its underlying mechanisms.Methods C57BL/6J mice were used to establish a model of SAH.The effects of TIMP1 on SAH outcomes were analysed by intraperitoneal injection of recombinant mouse TIMP1 protein(rm-TIMP1;250µg/kg).The roles of TIMP1 and its effectorβ1-integrin on astrocytes were observed by in vivo transduction with astrocyte-targeted adeno-associated virus carrying TIMP1 overexpression plasmid orβ1-integrin RNAi.The molecular mechanisms underlying TIMP1 andβ1-integrin interactions were explored in primary cultured astrocytes stimulated with red blood cells(RBCs).Results TIMP1 was upregulated after SAH.Administration of rm-TIMP1 mitigated SAH-induced early brain injury(EBI)in male and female mice.TIMP1 was primarily expressed in astrocytes;its overexpression in astrocytes led to increasedβ1-integrin expression in astrocytes,along with the preservation of astrocytic endfoot attachment to the endothelium and subsequent recovery of endothelial tight junctions.All of these effects were reversed by the knockdown ofβ1-integrin in astrocytes.Molecular analysis showed that TIMP1 overexpression decreased the RBC-induced ubiquitination ofβ1-integrin;this effect was partially achieved by inhibiting the interaction betweenβ1-integrin and the E3 ubiquitin ligase Trim21.Conclusion TIMP1 inhibits the interaction betweenβ1-integrin and Trim21 in astrocytes,thereby rescuing the ubiquitination of astrocyticβ1-integrin.It subsequently restores interactions between astrocytic endfeet and the endothelium,as well as BBB integrity,eventually mitigating SAH-induced EBI.展开更多
基金supported by the Knowledge Innovation Foundation of Chinese Academy of Sciences(No.KJCX2- YW-N24)the National Natural Science Foundation of China(No.40975080,10979061)
文摘Smog chamber experiments were performed to investigate the composition of products formed from photooxidation of aromatic hydrocarbon ethylbenzene. Vacuum ultraviolet photoionization mass spectrometer and aerosol time-of-flight mass spectrometer were used to measure the products in the gas and particle phases in real-time. Experimental results demonstrated that ethylphenol, methylglyoxal, phenol, benzaldehyde, and 2-ethylfurane were the predominant photooxidation products in both the gas and particle phases. However, there were some differences between detected gas phase products and those of particle phase, for example, 2-ethylfurane, ethylglyoxylic acid, nitroethylbenzene, 3,4-dioxopentanal and ethyl-nitrophenol were only existing in the particle-phase. The possible reaction mechanisms leading to these products were also discussed and proposed.
基金supported by the National Natural Science Foundation of China (No. 10979061,40975080)the Knowledge Innovation Foundation of Chinese Academy of Sciences (No. KJCX2-YW-N24)+1 种基金the Open Research Fund of Key Laboratory of Atmospheric Composition and Optical Radiation,Chinese Academy of Sciences (No. JJ10-04)the foundation of director of Anhui Institute of Optics and Fine Mechanics (No. Y03AG31147)
文摘The gas-phase organic compounds resulting from OH-initiated photooxidation of isoprene have been investigated on-line by VUV photoiortization mass spectrometry based on synchrotron radiation for the first time. The photoionization efficiency curves of the corresponding gaseous products as well as the chosen standards have been deduced by gating the interested peaks in the photoionization mass spectra while scanning the photon energy simultaneously, which permits the identification of the pivotal gaseous products of the photooxidation of isoprene, such as formaldehyde （10.84 eV）, formic acid （11.38 eV）, acetone （9.68 eV）, glyoxal （9.84 eV）, acetic acid （10.75 eV）, methacrolein （9.91 eV）, and methyl vinyl ketone （9.66 eV）. Proposed reaction mechanisms leading to the formation of these key products were discussed, which were completely consistent with the previous works of different groups. The capability of synchrotron radiation photoionization mass spectrometry to directly identify the chemical composition of the gaseous products in a simulation chamber has been demonstrated, and its potential application in related studies of atmospheric oxidation of ambient volatile organic compounds is anticipated.
文摘Background Astrocytes regulate blood-brain barrier(BBB)integrity,whereas subarachnoid haemorrhage(SAH)results in astrocyte dysregulation and BBB disruption.Here,we explored the involvement of tissue inhibitor of matrix metalloprotease-1(TIMP1)in astrocyte-mediated BBB protection during SAH,along with its underlying mechanisms.Methods C57BL/6J mice were used to establish a model of SAH.The effects of TIMP1 on SAH outcomes were analysed by intraperitoneal injection of recombinant mouse TIMP1 protein(rm-TIMP1;250µg/kg).The roles of TIMP1 and its effectorβ1-integrin on astrocytes were observed by in vivo transduction with astrocyte-targeted adeno-associated virus carrying TIMP1 overexpression plasmid orβ1-integrin RNAi.The molecular mechanisms underlying TIMP1 andβ1-integrin interactions were explored in primary cultured astrocytes stimulated with red blood cells(RBCs).Results TIMP1 was upregulated after SAH.Administration of rm-TIMP1 mitigated SAH-induced early brain injury(EBI)in male and female mice.TIMP1 was primarily expressed in astrocytes;its overexpression in astrocytes led to increasedβ1-integrin expression in astrocytes,along with the preservation of astrocytic endfoot attachment to the endothelium and subsequent recovery of endothelial tight junctions.All of these effects were reversed by the knockdown ofβ1-integrin in astrocytes.Molecular analysis showed that TIMP1 overexpression decreased the RBC-induced ubiquitination ofβ1-integrin;this effect was partially achieved by inhibiting the interaction betweenβ1-integrin and the E3 ubiquitin ligase Trim21.Conclusion TIMP1 inhibits the interaction betweenβ1-integrin and Trim21 in astrocytes,thereby rescuing the ubiquitination of astrocyticβ1-integrin.It subsequently restores interactions between astrocytic endfeet and the endothelium,as well as BBB integrity,eventually mitigating SAH-induced EBI.
