Sample records for ancrod

  1. Effects of Cardiopulmonary Bypass on Hemostasis (United States)


    Berry BR, et al. Enoxaparin for unstable angina and ancrod for cardiac surgery following heparin allergy. Ann Pharmacother 1996;30(5):476-480. 229...first hour [37,38]. PG^ is extremely unstable in plasma, and after 1 hour the recirculated platelets regain their ability to aggregate in the presence...compared, must be established after the induction of anesthesia and the opening of the chest , since anesthesia and surgery have been shown to reduce the

  2. Iron modulates the alpha chain of fibrinogen. (United States)

    Nielsen, Vance G; Jacobsen, Wayne K


    Iron-bound fibrinogen has been noted to accelerate plasmatic coagulation in patients with divergent conditions involving upregulation of heme oxygenase activity, including hemodialysis, Alzheimer's disease, sickle cell anemia, and chronic migraine. Our goal was to determine if a site of iron-fibrinogen interaction was on the alpha chain. Using thrombelastography, we compared the coagulation kinetic profiles of plasma exposed to 0-10 µM ferric chloride after activation of coagulation with thrombin generated by contact activation of plasma with the plastic sample cup or by exposure to 1 µg/ml of Calloselasma rhodostoma venom (rich in ancrod activity), which causes coagulation via polymerization of alpha chain monomers. Venom mediated coagulation always occurred before thrombin activated thrombus formation, and ferric chloride always diminished the time of onset of coagulation and increased the velocity of clot growth. Iron enhances plasmatic coagulation kinetics by modulating the alpha chain of fibrinogen.

  3. Protease activated receptors (PARS) mediation in gyroxin biological activity; Mediacao dos receptores ativados por proteases (PARs) em atividades biologicas da giroxina

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Jose Alberto Alves da


    Gyroxin is a serine protease enzyme from the South American rattlesnake (Crotalus durissus terrificus) venom; it is only partially characterized and has multiple activities. Gyroxin induces blood coagulation, blood pressure decrease and a neurotoxic behavior named barrel rotation. The mechanisms involved in this neurotoxic activity are not known. Whereas gyroxin is a member of enzymes with high potential to become a new drug with clinical applications such as thrombin, batroxobin, ancrod, tripsyn and kalicrein, it is important to find out how gyroxin works. The analysis on agarose gel electrophoresis and circular dichroism confirmed the molecules' integrity and purity. The gyroxin intravenous administration in mice proved its neurotoxicity (barrel rotation). In vivo studies employing intravital microscopy proved that gyroxin induces vasodilation with the participation of protease activated receptors (PARs), nitric oxide and Na+K+ATPase. The leukocytes' adherence and rolling counting indicated that gyroxin has no pro inflammatory activity. Gyroxin induced platelet aggregation, which was blocked by inhibitors of PAR1 and PAR4 receptors (SCH 79797 and tcY-NH{sub 2}, respectively). Finally, it was proved that the gyroxin temporarily alter the permeability of the blood brain barrier (BBB). Our study has shown that both the protease-activated receptors and nitric oxide are mediators involved in the biological activities of gyroxin. (author)

  4. Advances in Medical Revascularisation Treatments in Acute Ischemic Stroke

    Directory of Open Access Journals (Sweden)

    H. Asadi


    Full Text Available Urgent reperfusion of the ischaemic brain is the aim of stroke treatment and there has been ongoing research to find a drug that can promote vessel recanalisation more completely and with less side effects. In this review article, the major studies which have validated the use and safety of tPA are discussed. The safety and efficacy of other thrombolytic and anticoagulative agents such as tenecteplase, desmoteplase, ancrod, tirofiban, abciximab, eptifibatide, and argatroban are also reviewed. Tenecteplase and desmoteplase are both plasminogen activators with higher fibrin affinity and longer half-life compared to alteplase. They have shown greater reperfusion rates and improved functional outcomes in preliminary studies. Argatroban is a direct thrombin inhibitor used as an adjunct to intravenous tPA and showed higher rates of complete recanalisation in the ARTTS study with further studies which are now ongoing. Adjuvant thrombolysis techniques using transcranial ultrasound are also being investigated and have shown higher rates of complete recanalisation, for example, in the CLOTBUST study. Overall, development in medical therapies for stroke is important due to the ease of administration compared to endovascular treatments, and the new treatments such as tenecteplase, desmoteplase, and adjuvant sonothrombolysis are showing promising results and await further large-scale clinical trials.

  5. Serine proteinase inhibition by the active site titrant N alpha-(N, N-dimethylcarbamoyl)-alpha-azaornithine p-nitrophenyl ester. A comparative study. (United States)

    Ascenzi, P; Balliano, G; Gallina, C; Polticelli, F; Bolognesi, M


    Kinetics for the hydrolysis of the chromogenic active-site titrant N alpha-(N,N-dimethylcarbamoyl)-alpha-azaornithine p-nitrophenyl ester (Dmc-azaOrn-ONp) catalysed by bovine beta-trypsin, bovine alpha-thrombin, bovine Factor Xa, human alpha-thrombin, human Factor Xa, human Lys77-plasmin, human urinary kallikrein, Mr 33 000 and Mr 54 000 species of human urokinase, porcine pancreatic beta-kallikrein-A and -B and Ancrod (the coagulating serine proteinase from the Malayan pit viper Agkistrodon rhodostoma venom) have been obtained between pH 6.0 and 8.0, at 21.0 degrees C, and analysed in parallel with those for the enzymatic cleavage of N alpha-(N,N-dimethylcarbamoyl)-alpha-azalysine p-nitrophenyl ester (Dmc-azaLys-ONp). The enzyme kinetics are consistent with the minimum three-step catalytic mechanism of serine proteinases, the rate-limiting step being represented by the deacylation process. Bovine beta-trypsin kinetics are modulated by the acid-base equilibrium of the His57 catalytic residue (pKa approximately 6.9). Dmc-azaOrn-ONp and Dmc-azaLys-ONp bind stoichiometrically to the serine proteinase active site, and allow the reliable determination of the active enzyme concentration between 1.0 x 10-6 M and 3.0 x 10-4 M. The affinity and the reactivity for Dmc-azaOrn-ONp (expressed by Ks and k+2/Ks, respectively) of the serine proteinases considered are much lower than those for Dmc-azaLys-ONp. The very different affinity and reactivity properties for Dmc-azaOrn-ONp and Dmc-azaLys-ONp have been related to the different size of the ornithine/lysine side chains, and to the ensuing different positioning of the active-site titrants upon binding to the enzyme catalytic centre (i.e. to P1-S1 recognition). These data represent the first detailed comparative investigation on the catalytic properties of serine proteinases towards an ornithine derivative (i. e. Dmc-azaOrn-ONp).

  6. 蛇毒类凝血酶基因工程的研究进展%Research Progress on Cloning of Snake Venom Thrombin-like Enzymes

    Institute of Scientific and Technical Information of China (English)

    李家祺; 李谦; 唐松山; 李红枝


    蛇毒类凝血酶(Thrombin-like enzyme,TLE)是蛇毒中与血浆凝血酶性质相似的一类丝氨酸蛋白酶,所不同的是在蛇毒类凝血酶结构中已经没有纤维蛋白稳定因子激活组分.由于蛇毒类凝血酶在新药研究中扮演重要角色,比如来自Bothrops jararaca和Bothrops atrox蛇毒的立芷雪、来自东北白眉蝮蛇毒的邦停和来自尖吻蝮蛇毒的苏灵,它们是具有止血作用的新药;来自Gloydius shedaoensis和Gloydius ussuriensis蛇毒的东菱克栓酶、来自白眉蝮蛇和尖吻蝮蛇毒的降纤酶、来自Calloselasma rhodostoma蛇毒的安克洛酶和来自Crotalus adamanteus蛇毒的Crotalase,它们是具有溶栓作用的新药.这些药用蛋白质的来源和产量因有限的蛇毒原料而有很大限制,通过基因克隆可解决资源问题.文章综述了蛇毒类凝血酶的基因结构、糖基化特点和各种重组表达体系,为大量制备供临床和基础研究使用奠定基础.%Snake venom thrombin-like enzymes (snTLE) are one kind of serine proteases similar to thrombin from blood, but the basic difference between them is that snTLE has no XIII-activated domain to lead thrombosis in vivo or in vitro. Because snake venoms play very important role in pharmaceutics,for example Reptilase from Bothrops jararaca or Bothrops atrox snake venom, Bangtin from Agkistrodon halys snake venom,or Siding from Agkistrodon acutus snake venom,are hemostatic drugs. Defibrase from Gloydius shedaoensis ,Cloydius ussuriensis,Agkistrodon halys,or Agkistrodon acutus snake venom,Ancrod from Calloselasma rhodostoma snake venom, or Crotalase from Crotalus adamanteus snake venom, is thrombolytic drug. So the shortage of snake venom source can be overcome by using gene recombination method. The gene structures, protein glycosylation, and all kinds of cloning expression systems for snTLE protein are summarized in the paper,which will provide a basis for large-scale production of some snTLE proteins.