蚌蛙蛭抗凝血蛋自的分离及抗凝血特性(英文)

以超速离心和肝素琼脂糖亲和层析从蚌蛙蛭（Batracobdellakasmiana）的粗提取液中分离到2种抗凝血蛋白．抗凝血活性测定证明,这2种蛋白具有显著抑制凝血酶的活性而不具有抑制凝血因子Xa的活性．亲和层析的蛋白洗脱峰与抑制凝血酶的活力峰相吻合;因此,蚌蛙蛭的抗凝血蛋白是属于凝血酶特异性的抗凝血蛋白．这为进一步研究蚌蛙蛭抗凝血蛋白的抗凝血机理及其应用打下了基础．     

心房纤颤治疗新进展

房颤是一种常见的心律失常，其发病率随年龄的增加而升高，目前高血压、冠心病已逐渐成为老年房颤的最常见原因，现已公认房颤与脑卒中有很大关系，所以房颤病人进行转复治疗尤其抗凝治疗具特殊意义。在抗凝治疗过程中，应结合患者的年龄、临床危险因素及抗凝治疗的益处和潜在危险，合理使用抗凝药物。抗凝治疗有预防栓塞的作用，从而能显著降低卒中的发病率     

盐源山蛭抗凝血蛋白的分离及抗凝血特性分析

以肝素琼脂糖亲和层析和超速离心分离了盐源山蛭的抗凝血蛋白,抗凝血活性试验证明,该蛋白不抑制凝血因子Ｘａ的活性,而显著抑制凝血酶的活性,亲和层析的蛋白洗脱峰与抗凝血酶的活力峰相吻合,因此,盐源山蛭抗凝血蛋白属于凝血酶特异性的抗凝血蛋白。     

DNA-programmable nanoparticle crystallization

It was first shown more than ten years ago that DNA oligonucleotides can be attached to gold nanoparticles rationally to direct the formation of larger assemblies. Since then, oligonucleotide-functionalized nanoparticles have been developed into powerful diagnostic tools for nucleic acids and proteins, and into intracellular probes and gene regulators. In contrast, the conceptually simple yet powerful idea that functionalized nanoparticles might serve as basic building blocks that can be rationally assembled through programmable base-pairing interactions into highly ordered macroscopic materials remains poorly developed. So far, the approach has mainly resulted in polymerization, with modest control over the placement of, the periodicity in, and the distance between particles within the assembled material. That is, most of the materials obtained thus far are best classified as amorphous polymers, although a few examples of colloidal crystal formation exist. Here, we demonstrate that DNA can be used to control the crystallization of nanoparticle-oligonucleotide conjugates to the extent that different DNA sequences guide the assembly of the same type of inorganic nanoparticle into different crystalline states. We show that the choice of DNA sequences attached to the nanoparticle building blocks, the DNA linking molecules and the absence or presence of a non-bonding single-base flexor can be adjusted so that gold nanoparticles assemble into micrometre-sized face-centred-cubic or body-centred-cubic crystal structures. Our findings thus clearly demonstrate that synthetically programmable colloidal crystallization is possible, and that a single-component system can be directed to form different structures.     

Selection of single-stranded DNA molecules that bind and inhibit human thrombin.

Aptamers are double-stranded DNA or single-stranded RNA molecules that bind specific molecular targets. Large randomly generated populations can be enriched in aptamers by in vitro selection and polymerase chain reaction. But so far single-stranded DNA has not been investigated for aptamer properties, nor has a target protein been considered that does not interact physiologically with nucleic acid. Here we describe the isolation of single-stranded DNA aptamers to the protease thrombin of the blood coagulation cascade and report binding affinities in the range 25-200 nM. Sequence data from 32 thrombin aptamers, selected from a pool of DNA containing 60 nucleotides of random sequence, displayed a highly conserved 14-17-base region. Several of these aptamers at nanomolar concentrations inhibited thrombin-catalysed fibrin-clot formation in vitro using either purified fibrinogen or human plasma.     

Single-site enzymatic cleavage of yeast genomic DNA mediated by triple helix formation.

Physical mapping of chromosomes would be facilitated by methods of breaking large DNA into manageable fragments, or cutting uniquely at genetic markers of interest. Key issues in the design of sequence-specific DNA cleaving reagents are the specificity of binding, the generalizability of the recognition motif, and the cleavage yield. Oligonucleotide-directed triple helix formation is a generalizable motif for specific binding to sequences longer than 12 base pairs within DNA of high complexity. Studies with plasmid DNA show that triple helix formation can limit the operational specificity of restriction enzymes to endonuclease recognition sequences that overlap oligonucleotide-binding sites. Triple helix formation, followed by methylase protection, triple helix-disruption, and restriction endonuclease digestion produces near quantitative cleavage at the single overlapping triple helix-endonuclease site. As a demonstration that this technique may be applicable to the orchestrated cleavage of large genomic DNA, we report the near quantitative single-site enzymatic cleavage of the Saccharomyces cerevisiae genome mediated by triple helix formation. The 340-kilobase yeast chromosome III was cut uniquely at an overlapping homopurine-EcoRI target site 27 base pairs long to produce two expected cleavage products of 110 and 230 kilobases. No cleavage of any other chromosome was detected. The potential generalizability of this technique, which is capable of near quantitative cleavage at a single site in at least 14 megabase pairs of DNA, could enable selected regions of chromosomal DNA to be isolated without extensive screening of genomic libraries.     

Antisense c-myb oligonucleotides inhibit intimal arterial smooth muscle cell accumulation in vivo.

Synthetic antisense oligonucleotides have been used to dissect gene function in vitro. Technical difficulties prevented the use of this approach for investigating the effect of gene products in vivo. Here we report the use of local delivery of antisense c-myb oligonucleotide to suppress intimal accumulation of rat carotid arterial smooth muscle cells. Our results suggest that antisense oligonucleotides can be used to define the in vivo biological role of specific macromolecules in the blood vessel wall and could potentially serve as a new class of therapeutic agents for cardiovascular disorders.     

A mirror-symmetric cell division that orchestrates neuroepithelial morphogenesis

The development of cell polarity is an essential prerequisite for tissue morphogenesis during embryogenesis, particularly in the development of epithelia. In addition, oriented cell division can have a powerful influence on tissue morphogenesis. Here we identify a novel mode of polarized cell division that generates pairs of neural progenitors with mirror-symmetric polarity in the developing zebrafish neural tube and has dramatic consequences for the organization of embryonic tissue. We show that during neural rod formation the polarity protein Pard3 is localized to the cleavage furrow of dividing progenitors, and then mirror-symmetrically inherited by the two daughter cells. This allows the daughter cells to integrate into opposite sides of the developing neural tube. Furthermore, these mirror-symmetric divisions have powerful morphogenetic influence: when forced to occur in ectopic locations during neurulation, they orchestrate the development of mirror-image pattern formation and the consequent generation of ectopic neural tubes.     

靶向细胞凋亡的海洋抗肿瘤多肽药物研究进展

凋亡在肿瘤的形成和发展中具有重要功能,靶向凋亡通路已成为发展化疗药物的重要策略。海洋生物多肽是抗肿瘤药物的重要来源,并且已经发现的大多数抗肿瘤海洋多肽都可以通过诱导凋亡途径发挥抗肿瘤作用。本文针对这类海洋药物研发中存在的药物抗原性及药物来源等主要问题,综述了近年来发现的海洋多肽及其诱导细胞凋亡的信号通路。     

激励Stackelberg策略下的电价算法

讨论了电力市场中制定电价算法的问题.首先将对策论中的激励Stackelberg策略概念引入到简化了的电力市场系统模型中.从用户获取最大效用函数的角度出发,研究了适合于电力市场合理发展的动态电价的新方法.该算法较以往单一电价的制定更加合理,具有激励性质.根据电力公司的生产能力再结合当时当地用户对电力的需求,分别采用线性激励策略和非线性激励策略,制定更加合理有效的电价政策.利用MATLAB对所制定的两种激励策略进行了数值仿真,仿真结果说明所得方法的有效性和结果的实用性.     

原发性髂股静脉血栓形成诊断诊治探讨

三年来收治发病后三天内的急性原发性左髂股静脉血栓形成3例。第1例术后给肝素抗凝治疗,同时给低分子右旋醣酐、阿斯匹林、潘生丁等祛聚辅助治疗。出院后遗留下肢静脉功能不全。第2例术后除应用抗凝、祛聚等治疗外,还给尿激酶溶栓治疗,伤口两个多月才愈合,出院后下肢静脉功能良好。第3例单纯应用尿激酶溶栓,辅以祛聚药物,出院后下肢静脉功能良好。     

长白山北坡森林生态系统的生物生产量及化学能研究

通过对长白山北坡森林生态系统的生物生产量及化学能的测量，揭示长白山北坡森林生态系统能量的分配规律。研究结果表明，长白山北坡森林生态系统中以针阔混交林生物量最高，人工落叶松林的生产量最高，并得出红松（Pinus koraiensis）和水曲柳（Fraxinus mandshurica）的化学能模型，从而为合理开发利用森林资源提供科学依据。     

大肠杆菌核酸适配体筛选的研究

由于传统微生物检测存在步骤繁琐、耗费时间、成本较高等缺点,因此研发快速有效检测微生物的新技术新方法显得尤为必要.本文利用whole-cell SELEX技术,进行了大肠杆菌活细胞核酸适配体的筛选,对单链DNA的制备鉴定、每轮筛选核酸文库的检测、核酸适配体的扩增克隆等内容进行了研究,在筛选过程中成功制备了单链DNA,并对整个筛选过程的核酸适配体库进行监测,保证了筛选的顺利进行,并对核酸适配体库进行了扩增和克隆,最终获得靶向大肠杆菌的核酸适配体序列,这将有助于基于核酸适配体的微生物检测新方法的建立.     

抗凝血生物材料研究中的表面分析方法

开发抗凝血生物材料最主要的目的就是要找到一种在与人体血液和组织相接触后不会引起血栓、凝血和炎症等特性的高分子材料,而抗凝血生物材料的以上特性与其表面性质紧密相关.因此,需要对新合成的材料的表面性质进行表征.综述了近年来应用得比较广泛的7种用于抗凝血生物材料表面性质分析的常规方法和1种新兴的核分析方法,并以在研究中的运用为实例,介绍了各种方法的原理、特点以及一些不足,指出只有借助多种分析方法,才能全面了解抗凝血生物材料的表面结构.     

壁挂式燃气炉在晋城地区的应用

结合某小区实例,对晋城地区煤层气开发状况及家用壁挂式燃气炉的特点进行了详细分析,指出壁挂式燃气炉分户供暖的经济性较高,符合当前"节能减排"的战略思路,在晋城地区应合理推广使用。     

Effect of non-contacted bases on the affinity of 434 operator for 434 repressor and Cro

The repressor of phage 434 binds to six operator sites on the phage chromosome. A comparison of the sequences of these 14-base-pair (bp) operator sites reveals a striking pattern: at five of the six sites, the symmetrically arrayed outer eight base pairs (four in each half-site) are identical and the remaining site differs at only one position (Fig. 1b). In contrast, the sequences of the inner four base pairs are highly variable. Crystallographic analysis of the repressor-operator complex shows that at each half-site, the 'recognition alpha-helix' of the repressor is positioned in the major groove such that it could contact the outermost five base pairs, but not the innermost two (Fig. 1a). We show in this paper that the sequence of the central base pairs of the operator (two in each half-site) have a significant role in determining operator affinity for repressor, despite the evidence presented here and in the accompanying paper that these base pairs are not contacted by repressor. We also show that these central base pairs influence operator affinity for Cro, a second gene regulatory protein encoded by phage 434. We discuss the likely structural basis for this evidently indirect, but sequence-dependent, effect of the central base pairs of the operator on its affinity for the two regulatory proteins.     

Enhancing protein C interaction with thrombin results in a clot-activated anticoagulant.

Human protein C is a vitamin K-dependent plasma glycoprotein that circulates as an inactive zymogen. At the endothelial cell surface, thrombin in complex with the integral membrane protein thrombomodulin converts protein C to its active form by specific cleavage of an activation peptide. The activated form of protein C has potent anticoagulant activity as a feedback regulator of thrombin generation (reviewed in refs 4-6), and also has profibrinolytic, anti-ischaemic and anti-inflammatory properties. Protein C is effective in the treatment of model and human thrombotic diseases but, except when it has been used to treat genetic or acquired deficiencies and microvascular thrombosis, it is administered as the activated enzyme, which has a short biological half-life. We have altered two putative inhibitory acidic residues near the thrombin cleavage site, which results in a 30-fold increase in substrate utilization by alpha-thrombin. We combined these changes with a genetically altered glycoform to generate a zymogen protein C with a 60-fold increased cleavage rate by free alpha-thrombin, independent of its cofactor thrombomodulin. We show that this 'proform' of protein C, unlike the natural circulating zymogen, can be activated by thrombin generated in clotting human plasma, resulting in an inhibition of further clot formation. Our data therefore show that we have engineered a site-activated agent, which only has anticoagulant activity when significant amounts of thrombin are being generated.     

籼稻93-11和粳稻日本晴DNA插入缺失差异片段揭示的水稻籼-粳分化

碱基的插入/缺失(InDel)引起DNA序列变化并形成了DNA片段长度多态,可以用作遗传标记.为了评价基于籼稻93-11和粳稻日本晴全基因组序列比对获得的差异片段而设计的InDel引物在鉴定籼稻和粳稻两种生态型以及研究稻属不同物种之间亲缘关系的意义,采用45对InDel引物,对来自亚洲10个国家的49份籼稻、43份粳稻品种和24份野生稻进行了检验.结果表明,其中41对InDel引物鉴定籼稻或粳稻品种的准确率高于80%.主成分分析散点图显示:籼稻与粳稻存在明显的遗传分化;含AA基因组的野生稻物种与籼稻品种存在较近的亲缘关系;非AA基因组的野生稻物种不存在明显的籼-粳分化.并且证明了基于籼稻93-11和粳稻日本晴全基因组序列比对获得的InDel差异片段设计的引物可以用于栽培稻籼稻和粳稻品种的鉴定以及籼-粳分化问题的研究,及探索稻属不同物种间的亲缘关系.     

基于角点检测图像配准的一种新算法

提出了一种新的基于角点检测的图像配准方法，其核心思想是采用一种快速的基于图像灰度的角点检测新算法，通过沿圆弧曲线扫描获取角点信息，然后根据这些角点信息建立图像间角点的对应关系，并由此得到初配准参数，最后通过迭代过程以提高配准的精度。理论分析和实验结果表明，该算法对图像间的旋转角度没有限制，配准精度高而且计算量较小。