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Effects of strain, body mass, and thread tip preparation on the establishment of focal cerebral ischemia mouse models

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Neural Regeneration Research 2008年第1期3卷 61-65页

作者： xuemei chen yun xu Department of Neurology Gulou Hospital Affiliated to Medical College Nanjing University Nanjing 210008 Jiangsu Province China

BACKGROUND： What are the successful factors of the establishment of the thread-blocking method for focal cerebral ischemia/reperfusion mouse models？ OBJECTIVE： To study the effects of strain, body mass, and thread tip preparation for the establishment of focal cerebral ischemia mouse models by using middle cerebral artery occlusion （MCAO）. DESIGN： Observational contrast animal study. SETTING： Gulou Hospital, Medical College of Nanjing University. MATERIALS：（1） The following experiment was performed at the Animal Experimental Center, Gulou Hospital Affiliated to Medical College of Nanjing University from December 2006 to April 2007. Sixty male white Kunming mice, whose body masses were 18-22 g （n =40）, 25-29 g （n =10） and 30-33 g （n =10）, as well as 10 male C57BL/6J mice, whose body mass was 18-22 g, were provided by the Animal Experimental Center, Gulou Hospital Affiliated to Medical College of Nanjing University. All mice were 10-12 weeks old. The project received confirmed consent from the local ethics committee. （2）Experimental materials： tripheryltetrazolium hydrochloride （TTC） and 0.1% poly-L-lysine were provided by Sigma Company, USA; citromint was provided by Shanghai Lingfeng Chemical Company Limited. METHODS：（1） Strain comparison： Ten white Kunming mice （weighing 18-22 g） and ten C57BL/6J mice （weighing 18 - 22 g） were selected. （2） Comparison of body mass： Thirty white Kunming mice, whose body masses were 18-22 g （n =10）, 25-30 g （n =10）, and 30-35 g （n =10）, were divided into groups. （3） Comparison of thread tip preparation： White Kunming mice weighing 18-22 g were divided into a poly-L-lysine line group and general line group, with 10 mice in each group. Mice in these two groups, which were respectively treated with poly-L-lysine or nothing, underwent MCAO. （4） All experimental mice received MCAO. Three hours after ischemia, and 24 hours after reperfusion, neurological deficit scores were measured and a success rate of model establishment was calculate

关键词： mice ischemia/reperfusion animal model thread-blocking method

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Deciphering fungal metabolon coupling tandem inverse-electrondemand Diels-Alder reaction and semipinacol rearrangement for the biosynthesis of spiro polycyclic alkaloids

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Science China Chemistry 2025年第1期68卷 288-296页

作者： Shuai Liu Wen-Qiang xu Ying-Tong Di Man-cheng Tang Ding-Kang chen Ming-Ming Cao Yao-Wen Chang Hong-Yu Tang Chun-Mao Yuan Jun-Bo Yang Zhi-Li Zuo Han Guo Zi-Fei xu Ying Zeng yun-Dong Wu Xiao-Jiang Hao Key Laboratory of Phytochemistry and Natural Medicines (Chinese Academy of Sciences) Kunming Institute of Botany Chinese Academy of Sciences University of Chinese Academy of Sciences Lab of Computational Chemistry and Drug Design State Key Laboratory of Chemical Oncogenomics Peking University Shenzhen Graduate School Shenzhen Bay Laboratory State Key Laboratory of Microbial Metabolism School of Life Sciences & Biotechnology Shanghai Jiao Tong University State Key Laboratory of Functions and Applications of Medicinal Plants Guizhou Medical University Molecular Biology Experimental Center Germplasm Bank of Wild Species in Southwest China Kunming Institute of Botany Chinese Academy of Sciences yunnan Key Laboratory for Wild Plant Resources Kunming Institute of Botany Chinese Academy of Sciences Research Unit of Chemical Biology of Natural Anti-Virus Products Chinese Academy of Medical Sciences

In the intricate process of natural product biosynthesis, a metabolon can enhance metabolic flux by associating sequential enzymes. A fungal metabolon, comprising of flavin-dependent monooxygenase Spe F and P450 monooxygenase Spe G, is identified in the biosynthesis of spiro polycyclic alkaloids(+)-notoamide B and its diastereomer(+)-versicolamide B. Using notoamide E as a substance, Spe F/Spe G metabolon can control the stereoselectivity of its 2,3-epoxidation, followed by hydrogen atom ion at C-17 to generate reactive epoxide tau-m A with dienyl iminium unit. Subsequently,(+)-notoamide B and(+)-versicolamide B are produced via tandem nonenzymatic inverse-electron-demand Diels-Alder reaction and semipinacol rearrangement. This provides the first example of metabolon in the biosynthesis of spiro-prenylated indole alkaloids.

关键词： metabolon Diels-Alder reaction semipinacol rearrangement biosynthesis notoamides spiro polycyclic alkaloids

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A versatile synthetic strategy towards rare earth based metal-organic frameworks

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Science China Chemistry 2025年

作者： Quan Shi yun-Hao xu Ming-Hui chen Peng Zhao Wen-Bo Deng Ji Xiong Kai Guo Ya-Qing Feng Bao Zhang School of Chemical Engineering and Technology Tianjin University Tianjin Collaborative Innovation Center of Chemical Science and Engineering Guangdong Laboratory Chemistry & Fine Chemical Industry Jieyang Center

Rare earth metal-organic frameworks (RE-MOFs) have drawn wide attention owing to diverse network structures and various application ***,due to the unpredictable formation of the nodes,it is still challenging to design novel RE-MOFs.A novel versatile strategy was developed employing a RE-acetate complex (RE2(CH3COO)6·4H2O) as a precursor to construct RE-MOFs.2D RE-MOFs (RE-DBP) and 3D RE-MOFs (RE-TCPP) could be obtained by using dicarboxylic porphyrin ligands H2DBP and tetracarboxylic porphyrin ligands H2TCPP,*** RE-MOFs were further synthesized to verify the universality of the *** crystalline RE-MOFs could also be prepared at room temperature via the developed strategy,which could significantly promote large-scale preparation and practical application of *** proof of the concept,the performance of porphyrin-based RE-MOFs was investigated in the photocatalytic cycloaddition of CO2with *** the RE-DBP(Co) MOFs,Tb-DBP(Co) exhibited the best photocatalytic performance,which was also greater than that of the corresponding 3D MOF Tb-TCPP(Co) due to the optimal 2D structure and thus the accelerated photogenerated charge separation and transfer *** work not only provides a novel versatile strategy to design and develop RE-MOFs,but also proposes a promising approach for the potential bulk production of RE-MOFs at room temperature.

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microRNA biogenesis and stabilization in plants

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Fundamental Research 2023年第5期3卷 707-717页

作者： Ye xu xuemei chen Institute for Integrative Genome Biology University of CaliforniaRiversideCA 92521United States Department of Botany and Plant Sciences University of CaliforniaRiversideCA 92521United States School of Life Sciences Peking-Tsinghua Joint Center for Life SciencesPeking UniversityBeijing 100871China

MicroRNAs(miRNAs)are short endogenous non-coding RNAs that regulate gene expression at the posttranscriptional level in a broad range of eukaryotic *** animals,it is estimated that more than 60%of mammalian genes are targets of miRNAs,with miRNAs regulating cellular processes such as differentiation and *** plants,miRNAs regulate gene expression and play essential roles in diverse biological processes,including growth,development,and stress *** mutants with defective miRNA biogenesis are embryo lethal,and abnormal expression of miRNAs can cause severe developmental *** is therefore crucial that the homeostasis of miRNAs is tightly *** this review,we summarize the key mechanisms of plant miRNA biogenesis and *** provide an update on nuclear proteins with functions in miRNA biogenesis and proteins linking miRNA biogenesis to environmental triggers.

关键词： microRNAs Biogenesis Processing AGO1 pri-miRNA

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The plant Mediator and its role in noncoding RNA production

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Frontiers in Biology 2011年第2期6卷 125-132页

作者： yun Ju KIM xuemei chen Department of Botany and Plant Sciences and Institute of Integrative Genome Biology University of CaliforniaRiversideCA 92521USA

Mediator,a conserved multiprotein complex in animals,plants,and fungi,is a cofactor of RNA polymerase II(Pol II).It is known to promote basal Pol II-mediated transcription as well as bridge sequence-specific transcriptional regulators and Pol II to integrate regulatory *** II transcribes not only protein-coding genes but also intergenic regions to generate noncoding RNAs such as small RNAs(microRNAs and small interfering RNAs)and long noncoding ***,two plant-specific polymerases,Pol IV and Pol V,have evolved from Pol II and play a role in the production of small interfering RNAs and long noncoding RNAs at heterochromatic regions to maintain genome stability through transcriptional gene silencing(TGS).Recent studies have defined the composition of the plant Mediator and evaluated its role in noncoding RNA production in relationship to Pol II,Pol IV and Pol ***,we review the functions of Mediator and that of noncoding RNAs generated by Pol II,Pol IV and Pol V in plants,and discuss a role of Mediator in epigenetic regulation via noncoding RNA production.

关键词： small RNA noncoding RNA Mediator Pol II Pol IV Pol V

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Coupled elasto-plasticity damage constitutive models for concrete

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2013年第4期14卷 256-267页

作者： Qiang xu Jian-yun chen Jing LI Gang xu State Key Laboratory of Coastal and Offshore Engineering Dalian University of Technology School of Civil and Hydraulic Engineering Dalian University of Technology Plan and Design Institute of Daqing Oilfield Communication Company

The paper is to design and construct a coupled elasto-plasticity damage constitutive model for *** on the energy dissipation principle,the Hsieh-Ting-chen four-parameter yield function is *** model can reflect different strength characteristics of concrete in tension and compression,and reduce the limitation and lacuna of the traditional damage constitutive models for ***,numerical test for concrete stress-strain relation under uniaxial tension and compression is ***,the damage process of concrete gravity dam is calculated and analyzed in seismic *** with other damage constitutive models,the proposed model contains only one unknown parameter and the other parameters can be found in the Hsieh-Ting-chen four-parameter yield *** same damage evolution law,which is used for tension and compression,is good for determining stress-strain constitutive and damage characteristics in complex stress *** coupled damage constitutive models can be applied in analyzing damage of concrete gravity dam and arch dam.

关键词： Concrete Damage constitutive models Hsieh-Ting-chen four-parameter yield function Uniaxial tension Uniaxial compression Gravity dam Arch dam

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Correction method of airfoil thickness effect in hinge moment calculation of a folding wing

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Chinese Journal of Aeronautics 2020年第3期33卷 922-932页

作者： Hao xu Jinglong HAN Haiwei yun Xiaomao chen State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and AstronauticsNanjing 210016China Research Institute of Unmanned Aircraft Nanjing University of Aeronautics and AstronauticsNanjing 210016China

The influences of airfoil thickness on the aerodynamic loading distribution and the hinge moments of folding wing aircraft are presented in this *** traditional panel method shows deficiencies in the calculation of folding wing's hinge ***, a thickness correction strategy for the aerodynamic model with CFD results is proposed, and an aeroelastic flight simulation platform is constructed based on the secondary development of *** on the platform,the developed aerodynamic model is verified, then the flight-folding process of the folding wing aircraft is simulated, and the influences of airfoil thickness on the results are *** show that the developed aerodynamic model can effectively describe the thickness effect of the folding *** thickness, which cannot be considered by the panel method, has a great influence on the hinge moments during the folding process, and the thickness correction has great significance in the calculation of folding wing's hinge moments.

关键词： Aerodynamic correction Dynamics simulation Flight simulation Folding wing Hinge moment Morphing aircraft

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Mechanical Performance of Bio-inspired Bidirectional Corrugated Sandwich Pressure Shell Under External Hydrostatic Pressure

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China Ocean Engineering 2024年第2期38卷 297-312页

作者： ZHANG Yi chen Yue yun Lai LIANG xu Ocean College Zhejiang UniversityZhoushan 316000China Hainan Institute Zhejiang UniversitySanya 572000China

This paper aims to enhance the compression capacity of underwater cylindrical shells by adopting the corrugated sandwich structure of *** cuttlebone suffers uniaxial external compression,while underwater cylindrical shells are in a biaxial compressive stress *** suit the biaxial compressive stress state,a novel bidirectional corrugated sandwich structure is proposed to improve the bearing capacity of cylindrical *** static and buckling analysis for the sandwich shell and the unstiffened cylindrical shell with the same volume-weight ratio are studied by numerical *** is indicated that the proposed sandwich shell can effectively reduce the ratio between circumferential and axial stress from 2 to 1.25 and improve the critical buckling load by about 1.63 *** simulation shows that optimizing and adjusting the structural parameters could significantly improve the advantage of the sandwich ***,the hydrostatic pressure tests for shell models fabricated by 3D printing are carried *** to the experimental results,the overall failure position of the sandwich shell is at the center part of the sandwich *** has been found the average critical load of the proposed sandwich shell models exceeds two times that of the unstiffened shell ***,the proposed bio-inspired bidirectional corrugated sandwich structure can significantly enhance the pressure resistance capability of cylindrical shells.

关键词： bio-inspiration bidirectional corrugation sandwich shell external pressure buckling

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Equivalent low-order angular flux nonlinear finite difference equation of MOC transport calculation

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Nuclear Science and Techniques 2020年第12期31卷 139-151页

作者： Li-xun Liu chen Hao yun-Lin xu Fundamental Science On Nuclear Safety and Simulation Technology Laboratory Harbin Engineering UniversityHarbin 150001China Institute of Nuclear and New Energy Technology(INET) Tsinghua UniversityBeijing 100084China Purdue University West LafayetteIN 47907USA

The key issue in accelerating method of characteristics(MOC)transport calculations is in obtaining a completely equivalent low-order neutron transport or diffusion ***,an equivalent low-order angular flux nonlinear finite difference equation is proposed for MOC transport *** method comprises three essential features:(1)the even parity discrete ordinates method is used to build a low-order angular flux nonlinear finite difference equation,and different boundary condition treatments are proposed;(2)two new defined factors,i.e.,the even parity discontinuity factor and odd parity discontinuity factor,are strictly defined to achieve equivalence between the low-order angular flux nonlinear finite difference method and MOC transport calculation;(3)the energy group and angle are decoupled to construct a symmetric linear system that is much easier to *** equivalence of this low-order angular flux nonlinear finite difference equation is analyzed for two-dimensional(2D)pin,2D assembly,and 2D C5G7 benchmark *** results demonstrate that a low-order angular flux nonlinear finite difference equation that is completely equivalent to the pin-resolved transport equation is established.

关键词： Angular flux Equivalence Even parity discrete ordinates method Nonlinear finite difference

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CAS9 is a genome mutator by directly disrupting DNA-PK dependent DNA repair pathway

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Protein & Cell 2020年第5期11卷 352-365页

作者： Shuxiang xu Jinchul Kim Qingshuang Tang Qu chen Jingfeng Liu Yang xu xuemei Fu Cancer Research Institute Guangdong Provincial Key Laboratory of Cancer ImmunotherapySchool of Basic Medical SciencesSouthern Medical UniversityGuangzhou 510515China The Eighth Affiliated Hospital Sun Yat-sen UniversityShenzhen 518033China Division of Biological Sciences University of CaliforniaSan Diego9500 Gilman DriveLa JollaCA 92093USA Shenzhen Children’s Hospital Shenzhen 518026China

With its high efficiency for site-specific genome editing and easy manipulation,the clustered regularly interspaced short palindromic repeats(CRISPR)/CRISPR associated protein 9(CAS9)system has become the most widely used gene editing technology in biomedical *** addition,significant progress has been made for the clinical development of CRISPR/CAS9 based gene therapies of human diseases,several of which are entering clinical *** we report that CAS9 protein can function as a genome mutator independent of any exogenous guide RNA(gRNA)in human cells,promoting genomic DNA double-stranded break(DSB)damage and genomic ***9 interacts with the KU86 subunit of the DNA-dependent protein kinase(DNA-PK)complex and disrupts the interaction between KU86 and its kinase subunit,leading to defective DNA-PK-dependent repair of DNA DSB damage via non-homologous end-joining(NHEJ)***9 is a CAS9 variant with potentially higher fidelity and broader compatibility,and dCAS9 is a CAS9 variant without nuclease *** show that XCAS9 and dCAS9 also interact with KU86 and disrupt DNA DSB *** the critical roles of DNA-PK in maintaining genomic stability and the pleiotropic impact of DNA DSB damage responses on cellular proliferation and survival,our findings caution the interpretation of data involving CRISPR/CAS9-based gene editing and raise serious safety concerns of CRISPR/CAS9 system in clinical application.

关键词： KEYWORDS CAS9 DNA-PK DNA double-stranded breaks genetic instability DNA repair

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