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排序方式: 共有7041条查询结果,搜索用时 218 毫秒
941.
Yadong Yu Yu-Lin Kuang Dongsheng Lei Xiaobo Zhai Meng Zhang Ronald M. Krauss Gang Ren 《Journal of lipid research》2016,57(10):1879-1888
Human VLDLs assembled in the liver and secreted into the circulation supply energy to peripheral tissues. VLDL lipolysis yields atherogenic LDLs and VLDL remnants that strongly correlate with CVD. Although the composition of VLDL particles has been well-characterized, their 3D structure is elusive because of their variations in size, heterogeneity in composition, structural flexibility, and mobility in solution. Here, we employed cryo-electron microscopy and individual-particle electron tomography to study the 3D structure of individual VLDL particles (without averaging) at both below and above their lipid phase transition temperatures. The 3D reconstructions of VLDL and VLDL bound to antibodies revealed an unexpected polyhedral shape, in contrast to the generally accepted model of a spherical emulsion-like particle. The smaller curvature of surface lipids compared with HDL may also reduce surface hydrophobicity, resulting in lower binding affinity to the hydrophobic distal end of the N-terminal β-barrel domain of cholesteryl ester transfer protein (CETP) compared with HDL. The directional binding of CETP to HDL and VLDL may explain the function of CETP in transferring TGs and cholesteryl esters between these particles. This first visualization of the 3D structure of VLDL could improve our understanding of the role of VLDL in atherogenesis. 相似文献
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945.
Wei-Li?Fu Zhou?XiangEmail author Fu-Guo?Huang Shi-Qiang?Cen Gang?Zhong Xin?Duan Ming?Liu Frankie?Leung 《Cell and tissue banking》2016,17(1):161-169
Endothelial progenitor cells (EPC) derived from the circulation may be used to enhance neovascularization. Since the combination of granulocyte colony-stimulating factor (GCSF) and CXCR4 antagonist AMD3100 efficiently mobilizes hematopoietic stem cells into peripheral circulation, it may increase the pool of endogenously circulating EPC. We tested this hypothesis by administering GCSF and AMD3100 to adult rabbits and rats, isolating mononuclear cells from peripheral blood by Ficoll density gradient centrifugation, and characterizing the blood-derived EPC based on morphology, immunophenotyping, gene expression and other functional analyses. These EPC showed clonal growth similar to that of human umbilical vein endothelial cells when cultured in complete EGM-2 medium on collagen I-precoated culture plates. The EPC exhibited a typical cobblestone-like morphology and were relatively homogeneous by the third passage. The cells expressed the typical endothelial marker CD31 based on flow cytometry and fluorescence microscopy, formed capillary-like structures when cultured in Matrigel, internalized DiI-acetylated low-density lipoprotein, bound Ulex europaeus agglutinin-1, and expressed CD31 and several other endothelial markers (VEGFR2, VE-cadherin, Tie-2, eNOS, vWF) at significantly higher levels than bone marrow-derived mesenchymal stem cells. These results suggest that the combination of GCSF and AMD3100 can efficiently release stem cells into peripheral circulation and generate EPC that show the desired morphological, immunophenotypic and functional characteristics. This minimally invasive approach may be useful for autologous cell transplantation for postnatal neovasculogenesis and tissue repair. 相似文献
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947.
Scholten JC Culley DE Brockman FJ Wu G Zhang W 《Biochemical and biophysical research communications》2007,352(1):48-54
The sulfate reducing bacteria Desulfovibrio vulgaris and the methanogenic archaea Methanosarcina barkeri can grow syntrophically on lactate. In this study, a set of three closely located genes, DVU2103, DVU2104, and DVU2108 of D. vulgaris, was found to be up-regulated 2- to 4-fold following the lifestyle shift from syntroph to sulfate reducer; moreover, none of the genes in this gene set were differentially regulated when comparing gene expression from various D. vulgaris pure culture experiments. Although exact function of this gene set is unknown, the results suggest that it may play roles related to the lifestyle change of D. vulgaris from syntroph to sulfate reducer. This hypothesis is further supported by phylogenomic analyses showing that homologies of this gene set were only narrowly present in several groups of bacteria, most of which are restricted to a syntrophic lifestyle, such as Pelobacter carbinolicus, Syntrophobacter fumaroxidans, Syntrophomonas wolfei, and Syntrophus aciditrophicus. Phylogenetic analysis showed that all three individual genes in the gene set tended to be clustered with their homologies from archaeal genera, and they were rooted on archaeal species in the phylogenetic trees, suggesting that they were horizontally transferred from archaeal methanogens. In addition, no significant bias in codon and amino acid usages was detected between these genes and the rest of the D. vulgaris genome, suggesting the gene transfer may have occurred early in the evolutionary history so that sufficient time has elapsed to allow an adaptation to the codon and amino acid usages of D. vulgaris. This report provides novel insights into the origin and evolution of bacterial genes linked to the lifestyle change of D. vulgaris from a syntrophic to a sulfate-reducing lifestyle. 相似文献
948.
Zhang H Li J Barrington RA Liang G Qin G Liu DX 《Biochemical and biophysical research communications》2007,359(2):285-291
C1 inhibitor (C1INH), a complement regulatory protein, prevents endotoxin shock via a direct interaction of the amino-terminal domain with gram-negative bacterial lipopolysaccharide (LPS). Importantly, the cleaved, inactive C1INH still is an anti-endotoxin effector indicating the anti-endotoxin peptide that generates from the amino-terminal domain of C1INH. In this study, we first identified that a cleaved fragment within the major part of the amino-terminal domain in in vitro proteolytic analysis of C1INH had an ability to bind to LPS. We synthesized several peptides overlapping the C1INH cleaved fragment. Among these synthetic peptides, a 13-mer derivative peptide at position from 18 to 30, named N2((18-30)), exhibited the most powerful anti-endotoxin activity in vitro, enlightening that it was most strong at binding to LPS, inhibiting the interaction of LPS with LPS-binding protein (LBP), blocking LPS binding to CD14(+) cells, and suppressing production of tumor necrosis factor (TNF)-alpha by murine macrophages, RAW 264.7. In the murine endotoxin shock model, the peptide N2((18-30)) protected mice from LPS-induced lethal septic shock by inhibiting macrophage activation. These data indicate that the peptide N2((18-30)) derived from the amino-terminal region of C1INH is anti-endotoxin. 相似文献
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950.
长江中下游滩地植被与钉螺孳生关系的研究 总被引:33,自引:2,他引:31
对由莎草、苔草、狗牙根为优势种组成的杂草群落植被类型、由多种苔草、荻、为优势种组成的苔草、荻群落植被类型和由芦苇、菱笋、蒌蒿及蓼类为优势种组成的芦苇群落植被类型3种长江中下游滩地主要群落植被类型进行了钉螺密度与植被高度、钉螺密度与植被盖度之间的关系。结果表明:杂草群落植被类型,钉螺生存最适宜的植被高度为22.05cm、范围为15~47cm,钉螺生存最适宜的植被盖度为65.28%、范围为35%~90%;苔草、荻群落植被类型,钉螺生存最适宜的植被高度为22.69cm、范围为20~33cm,钉螺生存最适宜的植被盖度为67.80%、范围为35%~95%;芦苇群落植被类型,钉螺生存最适宜的植被高度为64.82cm、范围为72~78cm,钉螺生存最适宜植被盖度为63.95%、范围为1%~100%。这一研究结果对通过生态工程措施控制植被因子,实现抑螺防病的策略提供科学依据 相似文献