9 resultados para Heparin-binding Growth Factors
em Chinese Academy of Sciences Institutional Repositories Grid Portal
Resumo:
25%Al-Zn alloy coating performs better than hot dip galvanized coating and 55%Al-Zn-Si coating with regard to general seawater corrosion protection. This study deals with the interfacial intermetallic layer's growth, which affects considerably the corrosion resistance and mechanical properties of 25%Al-Zn alloy coatings, by means of three-factor quadratic regressive orthogonal experiments, The regression equation shows that the intermetallic layer thickness decreases rapidly with increasing content of Si added to the Zn-Al alloy bath, increases with rise in bath temperature and prolonging dip time. The most effective factor that determined the thickness of intermetallic layer was the amount of Si added to Zn-Al alloy bath, while the effect of bath temperature and dip time on the thickness of intermetallic layer were not very obvious.
Resumo:
A method based on capillary zone electrophoresis (CZE) was used to study the interaction between low molecular weight heparin (LMWH) and interleukin 2 (IL-2). The results showed that the increase of the concentration of LMWH led to the decrease of the peak height and the increase of the peak width of IL-2, but the peak areas were kept constant. The binding constant of IL-2 with LMWH was calculated as 1.2 x 10(6) M(-1) by Scatchard analysis, which is in good agreement with the results found in the references using enzyme-linked immunosorbent assay (ELISA). The results demonstrated that the interaction between IL-2 and LMWH is of fast on-and-off kinetic binding reaction. CZE might be used to study not only slow on-and-off rates interactions, but also fast on-and-off rates ones. The binding constant can be calculated easily, and the method can be applied to study a wide range of heparin-protein interactions. (c) 2005 Elsevier B.V. All rights reserved.
Resumo:
Recently, we have successfully constructed flat-lying DNA monolayers on a mica surface (J. Phys. Chem. B 2006, 110, 10792-10798). In this work, the effects of various factors including bridge ions, DNA species, and developing temperature on the configuration of DNA monolayers have been investigated by atomic force microscopy (AFM) in detail. AFM results show that the species of bridge ions and developing temperature play a crucial role during the formation process. For example, the divalent cation Zn2+ resulted in many DNA chains stuck side by side in the monolayers due to the strong interactions between it and DNA's bases or the mica surface. Most DNA chain's conglutinations disappeared when the developing temperature was higher than 40 degrees C. Cd2+ and Ca2+ produced more compact DNA monolayers with some obvious aggregations, especially for the DNA monolayers constructed by using Ca2+ as the bridge ion. Co2+ produced well-ordered, flat-lying DNA monolayers similar to that of Mg2+. Furthermore, it was found that the flat-lying DNA monolayers could still form on a mica surface when plasmid DNA pBR 322 and linear DNA pBR 322/Pst I were used as the DNA source. Whereas, it was hard to form DNA monolayers on a (3-aminopropyl)triethoxysilane-mica surface because the strong interactions between DNA and substrate prevented the lateral movement of DNA molecules.
Resumo:
Background: Endothelial cells (EC) shed endothelial microparticles (EMP) in activation and apoptosis. Objectives: We compared the antigenic expression of EMP species released during activation as compared to apoptosis, in three cell lines. Methods: EC from renal and brain microvascular (MiVEC) and coronary macrovascular (MaVEC) origin were incubated with TNF-alpha to induce activation, or deprived of growth factors to induce apoptosis. Antigens expressed on EMP and EC were assayed flow cytometrically and included constitutive markers (CD31, CD51/61, CD105), inducible markers (CD54, CD62E and CD106), and annexin V binding. Results: It was found that in apoptosis, constitutive markers in EMP were markedly increased (CD31>CD105), with a concomitant decrease in expression in EC. Annexin V EC surface binding and annexin V+ EMP were more sharply increased in apoptosis than in activation. In contrast, in activation, inducible markers in EMP were markedly increased in both EMP and EC (CD62E>CD54>CD 106). Coronary MaVEC released significantly less EMP than MiVEC. Conclusion: EC release qualitatively and quantitatively distinct EMP during activation compared to apoptosis. Analysis of EMP phenotypic signatures may provide clinically useful information on the status of the endothelium. (C) 2003 Elsevier Science Ltd. All rights reserved.
Resumo:
The pluripotency and self-renewal of embryonic stem cells (ESC) are regulated by a variety of cytokines/growth factors with some species differences. We reported previously that rabbit ESC (rESC) are more similar to primate ESC than to mouse ESC. However,
Resumo:
Principal Component and Canonical Correlation Analysis of the Environmental Factors Influencing the Growth of Caragana korshinskii Kom. in Grassland
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蝰科蛇毒中含有丰富的具有血管通透增强活性的蛋白组分,本论文结合生物化学与分子生物学手段对几种毒蛇的蛇毒血管内皮生长因子进行了研究。其中,从云南产菜花烙铁头(Trimeresurus jerdonii)蛇毒中分离得到一个血管内皮生长因子,TjsvVEGF,并研究了其活性与受体结合特性的关系。同时,对圆斑蝰蛇、蝮蛇、山烙铁头和竹叶青等几种蛇的svVEGFs进行了分子生物学研究。此外,我们还分离到了一个蛇毒丝氨酸蛋白酶类似物,TjsvSPH,还对该蛋白的理化性质进行了初步研究。 TjsvVEGF是一个表观分子量为29 kDa的二聚体蛋白,由两个相同大小的亚基组成。活性实验表明,它在10ng的剂量下即可明显提高血管通透性,活性强度与VEGF165相当。虽然TjsvVEGF的氨基酸序列与TfsvVEGF和Pm-VEGF具有较高的相似性,但是它们的受体结合特性却有很大差异。TjsvVEGF与VEGFR-1的结合能力很弱,而对VEGR-2有很高的亲和力。这说明,TjsvVEGF的活性主要是VEGFR-2介导的。最后,我们对导致TjsvVEGF对VEGFR-1低亲和力的原因进行了探讨。 利用PCR方法,我们从圆斑蝰蛇毒腺中得到了三种svVEGFs蛋白编码区长短不一的cDNA序列,其差异是由cDNA链中一段富含AG(3’拼接接受位点)的区段发生了核苷酸缺失产生的。蛋白编码区核苷酸的缺失导致其编码的三种svVEGF蛋白N末端的氨基酸序列和长短均产生较大差异。因此我们推测,蝰属svVEGFs蛋白N末端普遍较短可能是编码它们的mRNA前体对3’拼接点的不同选择产生的。同时,通过对cDNAs推导的氨基酸序列分析发现,蝮蛇svVEGF和山烙铁头svVEGF在与受体结合相关的多个重要位点上发生了氨基酸替换,提示它们是研究svVEGFs与VEGFR结合机制的良好材料。 通过分子筛、离子交换和亲和层析等方法,我们还从菜花烙铁头蛇毒中得到了一个不具有酶活性的丝氨酸蛋白酶类似物,命名为:TjsvSPH。内肽序列测定结果表明,TjsvSPH三联体结构中的组氨酸已突变为精氨酸,这很可能是导致其失去蛋白水解酶活性的主要原因。活性检测验表明,与许多已发现的蛇毒活性组分不同,TjsvSPH不具有蛋白水解酶活性,不能引起血小板聚集,也不抑制ADP和凝血酶诱导的血小板聚集。它对人血浆的复钙时间也没有影响。TjsvSPH的氨基酸序列与典型蛇毒丝氨酸蛋白酶Halystase和Calobin有约77%的一致性。它与同科属来源的蛇毒丝氨酸蛋白酶类似物氨基酸序列相似性高达92%以上,与不同科属的也有约74%以上的相似性。通过对Genbank中六种毒蛇所有丝氨酸蛋白酶及其类似物进化分析,我们推测,蛇毒丝氨酸蛋白酶类似物很可能是由蛇毒丝氨酸蛋白酶进化而来,并在进化过程中形成了一类独特的蛋白质。
Resumo:
Substantial progress has been made recently in extending the supramolecular assembly of biomimetic structures to vesicle-based sophisticated nanocomposites and mesostructures. We report herein the successful preparation of unilamellar surfactant vesicles coated with a monolayer of ring-shaped {Mo-154} polyoxometalate (POM) nanoclusters, (NH4)(28)[Mo-154 (NO)(14)O(448)Hi(4)(H2O)(70)].approximate to 350H(2)O, by coulomb attractions using preformed didodecyldimethylammonium bromide (DDAB) surfactant vesicles as templates. The resultant vesicle-templated supramolecular assemblies are robust (they do not disintegrate upon dehydration) both at room-temperature ambient and vacuum conditions, as characterized by conventional transmission electron microscopy (TEM) and atomic force microscopy (AFM). The flexibility of the complex soft assemblies was also revealed by AFM measurements. The effect of POM-vesicle coulomb attractions on the dimensions of the templating vesicles was also investigated by using dynamic light scattering (DLS).Although origins of the structure stability of the as-prepared supramolecular assemblies are not clear yet, the nanometer scale cavities and the related properties of macroions of the POM clusters may play an important role in it.