To develop a fast and sensitive liquid chromatography-mass spectrometry method for the determination of penehyclidine hydrochloride （PH） in beagle dog plasma. PH and diphenhydramine hydrochloride （internal standard...To develop a fast and sensitive liquid chromatography-mass spectrometry method for the determination of penehyclidine hydrochloride （PH） in beagle dog plasma. PH and diphenhydramine hydrochloride （internal standard, IS） were extracted with a solvent mixture of petroleum ether-ethyl ether （7：3）. Chromatographic separation was achieved on a reversed-phase Eclipse XDB-C18 column （4.6 mm × 150 mm, 5 um） using the eluent of methanol-water （5 mmol/L ammonium acetate） （90：10, v/v, pH 5.8） as mobile phase. The electrospray ionization source was set at the positive multiple reaction monitoring （MRM） mode. This method involved the use of the [M＋H]^＋ ions of PH and diphenhydramine hydrochloride at m/z 316.4- 128.2 and m/z 256.4-167.2. The calibration curve was linear in the range of 1-1000 ng/mL with a correlation coefficient of 0.9988. The lower limit of quantification was 0.05 ng/mL. The precision, accuracy and recovery of the method were acceptable. Following intravenous injection admires＇ tration at doses of 0.5, 1 and 5 mg/kg PH, the main pharmacokinetic parameters were as the followings, t1/2a 0.33 h, t1/2β 2.44 1% tmax 0.058 1% AUC and Cmax exhibited a linear increase along with the increase of dose. The two-compartment model fit the three dose groups. This method was sensitive, accurate and fast for the determination of concentration of PH in beagle dog plasma. It could be used in pharmacokinetic studies of PH.展开更多
Guillain-Barrésyndrome(GBS)is often triggered by a preceding bacterial or viral infection.Occasionally,it has been observed in association with acute hepatitis A,B and C,and three cases have been previously descr...Guillain-Barrésyndrome(GBS)is often triggered by a preceding bacterial or viral infection.Occasionally,it has been observed in association with acute hepatitis A,B and C,and three cases have been previously described in India in which GBS was associated with acute hepatitis E.A molecular mimicry mechanism is supposed to be involved in the pathogenesis of GBS triggered by infectious agents,although the nature of the shared epitopes has not been characterized in most instances,including that in the case of hepatotropic viruses.We report a case of GBS following acute hepatitis E in a European individual.The presence of antiganglioside GM2 antibodies in this patient suggested molecular mimicry involving ganglioside GM2 in the pathogenesis of GBS associated with hepatitis E.展开更多
The alkylation of toluene with 1,3-pentadiene to produce pentyltoluene was carded out to obtain 2,6-dimethylnaphalene, which is an important intermediate during the production of 2,6-naphthalene dicarboxylic acid. Bas...The alkylation of toluene with 1,3-pentadiene to produce pentyltoluene was carded out to obtain 2,6-dimethylnaphalene, which is an important intermediate during the production of 2,6-naphthalene dicarboxylic acid. Based on our previous work using anhydrous AlCl3 as catalyst, [bupy]BF4-AlCl3 ionic liquids were employed to catalyze the reaction of 1,3-pentadiene with toluene. The experimental results show that [bupy]BF4-AlCl3 ionic liquids are suitable for the reaction especially when the molar ratio of AlCl3 to [bupy]BF4 is 1.75 ： 1, and the reaction could proceed at the temperature as low as 0℃. It could be as active as pure AlCl3, but much more environmentally friendly.展开更多
Indoor smog chamber experiments have been conducted to investigate the dynamics of sec- ondary organic aerosol （SOA） formation from OH-initiated photo-oxidation of isoprene in the presence of organic seed aerosol. T...Indoor smog chamber experiments have been conducted to investigate the dynamics of sec- ondary organic aerosol （SOA） formation from OH-initiated photo-oxidation of isoprene in the presence of organic seed aerosol. The dependence of the size distributions of SOA on both the level of pre-existing particles generated in situ from the photo-oxidation of trace hydrocarbons of indoor atmosphere and the concentration of precursor, has been investi- gated. It was shown that in the presence of high-level seed aerosol and low-level isoprene （typical urban atmospheric conditions）, particle growth due to condensation of secondary organic products on pre-existing particles dominated; while in the presence of low-level seed aerosol and comparatively high-level isoprene （typical atmospheric conditions in rural re-gion）, bimodal structures appeared in the size distributions of SOA, which corresponded to new particle formation resulting from homogeneous nucleation and particle growth due to condensation of secondary organic products on the per-existing particles respectively. The effects of concentrations of organic seed particles on SOA were also investigated. The particle size distributions evolutions as well as the corresponding formation rates of new particles in different conditions were also estimated.展开更多
The kinetic study of the anionic polymerization of isoprene is carried out in tetrahy-drofuran(THF), using n-BuLi as initiator. Kinetic parameters are obtained, which comprise chain propagation rate constant, kp, and ...The kinetic study of the anionic polymerization of isoprene is carried out in tetrahy-drofuran(THF), using n-BuLi as initiator. Kinetic parameters are obtained, which comprise chain propagation rate constant, kp, and partial rate constants, k3 and k4 + k5, propagation orders with respect to monomer and active species concentrations, α and β, real activation energy, E, as well as partial activation energies, E3 and E4+5 and so on. The relationship between the microstruc-ture of polyisoprene and the ratio of [THF]/[n-BuLi] has been investigated. On the basis of the studies mentioned above, a reasonable mechanism of the anionic polymerization of isoprene in THF is proposed.展开更多
AIM： To investigate the seroprevalence and molecular characteristics of hepatitis E virus （HEV） in the illegal blood donors （IBDs） of central China in the early 1990s.
Ferrocenium monocations as photoinitiators for cationic photopolymerization suffer from a limitation of low absorption and low reactivity under high-pressure Hg lamp. Here, a ferrocenium dication salt, biphenyl bis [...Ferrocenium monocations as photoinitiators for cationic photopolymerization suffer from a limitation of low absorption and low reactivity under high-pressure Hg lamp. Here, a ferrocenium dication salt, biphenyl bis [π-cyclopentadienyl）iron] hexafluorophosphate （[bis（Cp-Fe）-biphenyl] （PF6）2 was synthesized by the ligand exchange reaction between ferrocene and biphenyl. The chemical structure was characterized with FTIR and ^1HNMR. The separation of ferrocenium monocation cyclopentadien-iron-biphenyl hexafluorophosphate （[Cp-Fe-biphenyl] PF6） and dication [bis（Cp-Fe）-biphenyl] （PF6）2 was carried out by column chromatography. The photoactivity of initiating photopolyinerization of epoxide ER14221 was studied as a cationic photoinitiator. [Bis（Cp-Fe）-biphenyl] （PF6）2 can efficiently absorb radiation above 300nm and its photoactivity is higher than that of its monocation.展开更多
Dynamic regulation of histone methylation/demethylation plays an important role during development. Mutations and truncations in human plant homeodomain （PHD） finger protein 8 （PHF8） are associated with X-linked m...Dynamic regulation of histone methylation/demethylation plays an important role during development. Mutations and truncations in human plant homeodomain （PHD） finger protein 8 （PHF8） are associated with X-linked mental retardation and facial anomalies, such as a long face, broad nasal tip, cleft lip/cleft palate and large hands, yet its molecular function and structural basis remain unclear. Here, we report the crystal structures of the catalytic core of PHF8 with or without α-ketoglutarate （α-KG） at high resolution. Biochemical and structural studies reveal that PHF8 is a novel histone demethylase specific for di- and mono-methylated histone H3 lysine 9 （H3K9me2/1）, but not for H3K9me3. Our analyses also reveal how human PHF8 discriminates between methylation states and achieves sequence specificity for methylated H3K9. The in vitro demethylation assay also showed that the F279S mutant observed in clinical patients possesses no demethylation activity, suggesting that loss of enzymatic activity is crucial for pathogenesis of PHF8 patients. Taken together, these results will shed light on the molecular mechanism underlying PHF8-associated developmental and neurological diseases.展开更多
The present work contributed to a new developed production method for enhancing the quality of isoamylene （IA） by adding a small amount of tertiary amyl alcohol （TAA） to the catalyst of strong acid cation exchange...The present work contributed to a new developed production method for enhancing the quality of isoamylene （IA） by adding a small amount of tertiary amyl alcohol （TAA） to the catalyst of strong acid cation exchange resin. TAA improved the selectivity of 2-methyl-2-butene （2M2B） at a high conversion level for the isomerization of IA. Compared with the other results from the current IA units, the conversion of 2-methyl- 1-butene （2M1B）, the mass ratio of 2M2B to 2M1B and the selectivity of 2M2B were increased from 0.5474, 7.32 and 0.6864 to 0.72, 12 and 0.95, respectively, while the dimers content in the products decreased from 4.38% to below 1.0%. Optimized conditions for IA isomerization consisted of temperature between 28 and 33℃ and system pressure of 0.5 MPa, weight hourly space velocity of 8.0 h-1 with TAA mass fraction of 0.7%-0.9% in raw material. The results in lab supported bases for the developed process in industrial application which was later proved to be successful. In addition, a possible mechanism of the isomerization process was speculated to propose a key step of water formation in the TAA-added isomerization process and a verified experiment was conducted to support this speculation.展开更多
C2 prenylated indoles are widespread in a variety of bioactive natural alkaloids.Therefore,theselective installation of prenyl group at C2 position of NH indoles is of great significance.However,the known protocols ge...C2 prenylated indoles are widespread in a variety of bioactive natural alkaloids.Therefore,theselective installation of prenyl group at C2 position of NH indoles is of great significance.However,the known protocols generally require a multi‐step procedure and stoichiometric promoters.Hereinwe develop a one‐step C2 prenylation of NH indole with cheap tert‐prenyl alcohol enabled by acidcatalysis.Salient features include good regioselectivity,step‐and atom‐economy,broad substratescope,and simple catalytic system.The mechanistic investigations demonstrate that both C2prenylation and C3 prenylation/migration pathways are engaged in the reaction.Notably,this practicalstrategy can be applied to the late‐stage diversification of tryptophan‐based peptides and concisesynthesis of tryprostatin B.展开更多
The composition of HMW-GS and pentosan and its various component contents in different wheat varieties were analyzed. According to scores of these subunits in several wheat varieties, the correlation relationship betw...The composition of HMW-GS and pentosan and its various component contents in different wheat varieties were analyzed. According to scores of these subunits in several wheat varieties, the correlation relationship between the composition of HMW-GS, subunit combination types and pentosan, various components and component ratio were ascertained. The results showed that HMW-GSs were very diverse which had 11 types. In different varieties, the variation of Ara was obvious while Xyl was not; pentosan and its various component contents were very different, and their coefficient of variability was quite high. The majority of parameters had a significant negative correlation with Glu-1 where Glu-D1 was stronger than other two loci. N, 7, 17＋18 and 2＋12 subunits had influence on pentosan and its various component contents. But some subunits such as 1 and 5＋ 10 which are good for baking quality had little contribution to pentosan and various component contents. The pentosan and various component contents were higher in the varieties which had （N, 7, 2＋12） subunit combinations. Additionally, the 21 varieties were classified into 4 categories according to HMW-GS scores and pentosan content.展开更多
文摘To develop a fast and sensitive liquid chromatography-mass spectrometry method for the determination of penehyclidine hydrochloride （PH） in beagle dog plasma. PH and diphenhydramine hydrochloride （internal standard, IS） were extracted with a solvent mixture of petroleum ether-ethyl ether （7：3）. Chromatographic separation was achieved on a reversed-phase Eclipse XDB-C18 column （4.6 mm × 150 mm, 5 um） using the eluent of methanol-water （5 mmol/L ammonium acetate） （90：10, v/v, pH 5.8） as mobile phase. The electrospray ionization source was set at the positive multiple reaction monitoring （MRM） mode. This method involved the use of the [M＋H]^＋ ions of PH and diphenhydramine hydrochloride at m/z 316.4- 128.2 and m/z 256.4-167.2. The calibration curve was linear in the range of 1-1000 ng/mL with a correlation coefficient of 0.9988. The lower limit of quantification was 0.05 ng/mL. The precision, accuracy and recovery of the method were acceptable. Following intravenous injection admires＇ tration at doses of 0.5, 1 and 5 mg/kg PH, the main pharmacokinetic parameters were as the followings, t1/2a 0.33 h, t1/2β 2.44 1% tmax 0.058 1% AUC and Cmax exhibited a linear increase along with the increase of dose. The two-compartment model fit the three dose groups. This method was sensitive, accurate and fast for the determination of concentration of PH in beagle dog plasma. It could be used in pharmacokinetic studies of PH.
文摘Guillain-Barrésyndrome(GBS)is often triggered by a preceding bacterial or viral infection.Occasionally,it has been observed in association with acute hepatitis A,B and C,and three cases have been previously described in India in which GBS was associated with acute hepatitis E.A molecular mimicry mechanism is supposed to be involved in the pathogenesis of GBS triggered by infectious agents,although the nature of the shared epitopes has not been characterized in most instances,including that in the case of hepatotropic viruses.We report a case of GBS following acute hepatitis E in a European individual.The presence of antiganglioside GM2 antibodies in this patient suggested molecular mimicry involving ganglioside GM2 in the pathogenesis of GBS associated with hepatitis E.
文摘The alkylation of toluene with 1,3-pentadiene to produce pentyltoluene was carded out to obtain 2,6-dimethylnaphalene, which is an important intermediate during the production of 2,6-naphthalene dicarboxylic acid. Based on our previous work using anhydrous AlCl3 as catalyst, [bupy]BF4-AlCl3 ionic liquids were employed to catalyze the reaction of 1,3-pentadiene with toluene. The experimental results show that [bupy]BF4-AlCl3 ionic liquids are suitable for the reaction especially when the molar ratio of AlCl3 to [bupy]BF4 is 1.75 ： 1, and the reaction could proceed at the temperature as low as 0℃. It could be as active as pure AlCl3, but much more environmentally friendly.
文摘Indoor smog chamber experiments have been conducted to investigate the dynamics of sec- ondary organic aerosol （SOA） formation from OH-initiated photo-oxidation of isoprene in the presence of organic seed aerosol. The dependence of the size distributions of SOA on both the level of pre-existing particles generated in situ from the photo-oxidation of trace hydrocarbons of indoor atmosphere and the concentration of precursor, has been investi- gated. It was shown that in the presence of high-level seed aerosol and low-level isoprene （typical urban atmospheric conditions）, particle growth due to condensation of secondary organic products on pre-existing particles dominated; while in the presence of low-level seed aerosol and comparatively high-level isoprene （typical atmospheric conditions in rural re-gion）, bimodal structures appeared in the size distributions of SOA, which corresponded to new particle formation resulting from homogeneous nucleation and particle growth due to condensation of secondary organic products on the per-existing particles respectively. The effects of concentrations of organic seed particles on SOA were also investigated. The particle size distributions evolutions as well as the corresponding formation rates of new particles in different conditions were also estimated.
文摘The kinetic study of the anionic polymerization of isoprene is carried out in tetrahy-drofuran(THF), using n-BuLi as initiator. Kinetic parameters are obtained, which comprise chain propagation rate constant, kp, and partial rate constants, k3 and k4 + k5, propagation orders with respect to monomer and active species concentrations, α and β, real activation energy, E, as well as partial activation energies, E3 and E4+5 and so on. The relationship between the microstruc-ture of polyisoprene and the ratio of [THF]/[n-BuLi] has been investigated. On the basis of the studies mentioned above, a reasonable mechanism of the anionic polymerization of isoprene in THF is proposed.
基金Supported by The Natural Science Foundation of Maanshan,China (2008-40) (To Zhan SW and Zheng JX)
文摘AIM： To investigate the seroprevalence and molecular characteristics of hepatitis E virus （HEV） in the illegal blood donors （IBDs） of central China in the early 1990s.
基金Supported by the National Natural Science Foundation of China （20676012）.
文摘Ferrocenium monocations as photoinitiators for cationic photopolymerization suffer from a limitation of low absorption and low reactivity under high-pressure Hg lamp. Here, a ferrocenium dication salt, biphenyl bis [π-cyclopentadienyl）iron] hexafluorophosphate （[bis（Cp-Fe）-biphenyl] （PF6）2 was synthesized by the ligand exchange reaction between ferrocene and biphenyl. The chemical structure was characterized with FTIR and ^1HNMR. The separation of ferrocenium monocation cyclopentadien-iron-biphenyl hexafluorophosphate （[Cp-Fe-biphenyl] PF6） and dication [bis（Cp-Fe）-biphenyl] （PF6）2 was carried out by column chromatography. The photoactivity of initiating photopolyinerization of epoxide ER14221 was studied as a cationic photoinitiator. [Bis（Cp-Fe）-biphenyl] （PF6）2 can efficiently absorb radiation above 300nm and its photoactivity is higher than that of its monocation.
基金Supplementary information is linked to the online version of the paper on the Cell Research website.Acknowledgments We thank Dr Dawei Li （China Agricultural University） for generously providing us with the experimental conditions during the early stages of this project. We thank Dr Ruiming Xu （Institute of Biophysics, Chinese Academy of Sciences） for critical reading of this manuscript and advice. We thank Dr Pinchao Mei （Chinese Academy of Medical Sciences and Peking Union Medical College）, Xinqi Liu （Nankai University） and Jiemin Wong （East China Normal University） for discussions and advice. The synchrotronradiation experiments were performed at Shanghai Synchrotron Radiation Facility （SSRF） and NE3A in the Photon Factory. Z.C. is supported by the National Basic Research Program of China （973 Program, 2009CB825501）, the National Natural Science Foundation of China （30870494 and 90919043）, the New Century Excellent Talents in University （NCET-07-0808） and the Innovative Project of SKLAB. S. H. is supported by the National Key Laboratory Special Fund 2060204. Z. D. is supported by the National Natural Science Foundation of China （J0730639）.
文摘Dynamic regulation of histone methylation/demethylation plays an important role during development. Mutations and truncations in human plant homeodomain （PHD） finger protein 8 （PHF8） are associated with X-linked mental retardation and facial anomalies, such as a long face, broad nasal tip, cleft lip/cleft palate and large hands, yet its molecular function and structural basis remain unclear. Here, we report the crystal structures of the catalytic core of PHF8 with or without α-ketoglutarate （α-KG） at high resolution. Biochemical and structural studies reveal that PHF8 is a novel histone demethylase specific for di- and mono-methylated histone H3 lysine 9 （H3K9me2/1）, but not for H3K9me3. Our analyses also reveal how human PHF8 discriminates between methylation states and achieves sequence specificity for methylated H3K9. The in vitro demethylation assay also showed that the F279S mutant observed in clinical patients possesses no demethylation activity, suggesting that loss of enzymatic activity is crucial for pathogenesis of PHF8 patients. Taken together, these results will shed light on the molecular mechanism underlying PHF8-associated developmental and neurological diseases.
文摘The present work contributed to a new developed production method for enhancing the quality of isoamylene （IA） by adding a small amount of tertiary amyl alcohol （TAA） to the catalyst of strong acid cation exchange resin. TAA improved the selectivity of 2-methyl-2-butene （2M2B） at a high conversion level for the isomerization of IA. Compared with the other results from the current IA units, the conversion of 2-methyl- 1-butene （2M1B）, the mass ratio of 2M2B to 2M1B and the selectivity of 2M2B were increased from 0.5474, 7.32 and 0.6864 to 0.72, 12 and 0.95, respectively, while the dimers content in the products decreased from 4.38% to below 1.0%. Optimized conditions for IA isomerization consisted of temperature between 28 and 33℃ and system pressure of 0.5 MPa, weight hourly space velocity of 8.0 h-1 with TAA mass fraction of 0.7%-0.9% in raw material. The results in lab supported bases for the developed process in industrial application which was later proved to be successful. In addition, a possible mechanism of the isomerization process was speculated to propose a key step of water formation in the TAA-added isomerization process and a verified experiment was conducted to support this speculation.
文摘C2 prenylated indoles are widespread in a variety of bioactive natural alkaloids.Therefore,theselective installation of prenyl group at C2 position of NH indoles is of great significance.However,the known protocols generally require a multi‐step procedure and stoichiometric promoters.Hereinwe develop a one‐step C2 prenylation of NH indole with cheap tert‐prenyl alcohol enabled by acidcatalysis.Salient features include good regioselectivity,step‐and atom‐economy,broad substratescope,and simple catalytic system.The mechanistic investigations demonstrate that both C2prenylation and C3 prenylation/migration pathways are engaged in the reaction.Notably,this practicalstrategy can be applied to the late‐stage diversification of tryptophan‐based peptides and concisesynthesis of tryprostatin B.
文摘The composition of HMW-GS and pentosan and its various component contents in different wheat varieties were analyzed. According to scores of these subunits in several wheat varieties, the correlation relationship between the composition of HMW-GS, subunit combination types and pentosan, various components and component ratio were ascertained. The results showed that HMW-GSs were very diverse which had 11 types. In different varieties, the variation of Ara was obvious while Xyl was not; pentosan and its various component contents were very different, and their coefficient of variability was quite high. The majority of parameters had a significant negative correlation with Glu-1 where Glu-D1 was stronger than other two loci. N, 7, 17＋18 and 2＋12 subunits had influence on pentosan and its various component contents. But some subunits such as 1 and 5＋ 10 which are good for baking quality had little contribution to pentosan and various component contents. The pentosan and various component contents were higher in the varieties which had （N, 7, 2＋12） subunit combinations. Additionally, the 21 varieties were classified into 4 categories according to HMW-GS scores and pentosan content.
