CANINE COAGULOPATHIES

这个子项目是利用由NIH/NCRR资助的中心拨款提供的资源的许多研究子项目之一。子项目和调查员(PI)可能从另一个NIH来源获得了主要资金，因此可能会出现在其他CRISE条目中。列出的机构是针对中心的，而不一定是针对调查员的机构。MANV遗传性凝血病在犬中已有报道，但这些疾病很少被描述为疾病同源，以研究其发病机制，并开发新的治疗方法，包括重组治疗和基因转移。纤维蛋白原缺乏症：我们发现了一只混血犬，由于严重的低纤维蛋白原血症，术后出血过多。这只狗有各自延长的筛查凝血时间，从功能和蛋白质分析来看，纤维蛋白原水平非常低。缺乏纤维蛋白原会阻止任何纤维蛋白凝块的形成，也可能会影响伤口的愈合。这是唯一一种自然发生的低纤维蛋白原血症动物，尽管已经产生了转基因小鼠。由于我们可以接触到这只狗，计划进行研究，以进一步表征这种缺陷的生化和分子基础。因子VII缺乏症我们已经在宠物种群中发现了几只由于遗传性因子VII缺乏而有轻微到中度出血倾向的比格犬。这些动物的控制因子VII的活性一直保持在5%，而且没有发现抑制物。在制药公司的研究动物群体中也发现了其他受影响的比格犬，它们正在进行基于部分凝血活酶时间延长的药物研究。重组人凝血因子VII最近被证明对包括血友病在内的各种凝血疾病有效，因为它可以绕过这一缺陷。因此，分子鉴定和建立缺乏凝血因子VII的犬群将是非常可取的。这些研究与费城儿童医院的Mary Beth Callan VMD和Kathy High MD博士合作，导致发现了一个错义突变和一个各自功能失调的蛋白质。一种简单可靠的DNA测试已经被开发出来，用于筛查携带者和因子VII缺陷的比格犬，从而允许建立一个群体来研究新的基因转移方法。血友病A：在最初描述了与血友病人类的主要分子机制相似的因子缺失犬群中的倒位突变后，我们一直在与美国国立卫生研究院的Jay Lozier博士合作，检查其他血友病狗的DNA中的这种倒位突变。在最初的五只狗中，没有一只有这种形式的分子缺陷，进一步的研究正在进行中。凝血因子XI缺乏症：我们早些时候已经描述了克里蓝梗的凝血因子XI缺乏症，它经历了手术后出血性素质的延迟。最近，我们从一家主要饲养者那里发现了两只缺陷犬，并计划与之合作调查这种分子缺陷。这应该是很容易实现的，因为整个基因组序列现在可以从犬类基因组计划中获得。关于确切的遗传方式(隐性、不完全显性)仍然存在疑问，目前除了新鲜冰冻血浆之外，没有其他治疗方案可用。尽管有缺乏凝血因子XI的牛，但这是唯一适合进一步实验室研究新治疗策略的自然动物。Von Willebrand病杜宾犬I型von Willebrand病的发病率很高。I型指的是所有多聚体大小的von Willebrand因子的比例亏缺。我们利用这个动物模型来进一步表征去氨加压素的作用，去氨加压素是一种血管加压素类似物，通常用于治疗人类von Willebrand病，但其机制尚不清楚。我们了解到，去氨加压素的作用不依赖于血小板相关的von Willebrand因子，也不单独或根本不与von Willebrand因子的多聚体大小有关。与内皮相关的进一步机制正在研究中。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Manv hereditary coagulopathies have been reported in dogs and few of these disorders have been characterized and serve as disease homologues to study the pathogenesis and to develop novel therapies including recombinant therapy and gene transfer. Fibrinogen Deficiency: We have identified a mixed breed dog with excessive post-operative hemorrhage due to a severe hypofibrinogenemia. This dog has severally prolonged screening coagulation times and by functional as well as protein assays very low fibrinogen levels. A lack of fibrinogen prevents the formation of any fibrin clot and also is expected to affect wound healing. This is the only animal with a naturally occurring hypofibrinogenemia, although transgenic mice have been produced. As we have access to this dog studies are planned to further characterize the biochemical and molecular basis of this defect. Factor VII Deficiency We have identified several Beagles in the pet population with a mild to moderate bleeding tendency due to a hereditary factor VII deficiency. These animals have persistently 5% of control factor VII activity and no inhibitor has been found. Other affected Beagles have been found in research animal colonies of pharmaceutical companies, while performing drug studies based upon a prolonged partial thromboplastin time. Recombinant human factor VII has recently been shown to be effective in a variety of coagulopathies including hemophilia as it can bypass the defect. Therefore the molecular characterization and establishment of a dog colony with factor VII deficiency would be highly desirable. These studies in collaboration with Mary Beth Callan VMD and Kathy High MD PhD at the Children Hospital of Philadelphia, led to the discover of a single missense mutation and a severally dysfunctional protein. A simple reliable DNA test has been developed to screen for carriers and factor VII deficient Beagles, thereby permitting the establishment of a colony to study novel gene transfer approaches. Hemophilia A: After the initial description of an inversion mutation in a factor VIII deficient dog colony similar to what is the major molecular mechanism in hemophilic humans, we have been examining other hemophilic dogs¿ DNA for this inversion in collaboration with Jay Lozier PhD at NIH. Of the five initiallydogs none had this form of a molecular defect and further studies are in progress. Factor XI Deficiency: We had earlier described factor XI deficiency in Kerry Blue Terriers which experience a delayed post-operative hemorrhagic diathesis. Recently we identified two deficient dogs from a major breeder and with cooperation we are planning to investigate the molecular defect. This should be readily achievable as the entire genomic sequence is now available from the canine genome project. There are still questions regarding the precise mode of inheritance (recessive verus incomplete dominant) and no other therapeutic options other than fresh frozen plasma are currently available. Although there are cattle with factor XI deficiency, this is the only naturally occurring animal suitable for further labortary investigations of novel therapeutic strategies. Von Willebrand Disease Doberman pinschers have a high prevalence of type I von Willebrand disease. Type I refers to the proportional deficiency of all multimeric sizes of von Willebrand factor. We have utilized this animal model to further characterize the effect of desmopressin, a vasopressin analog, which is commonly used in the treatment of human von Willebrand disease but its mechanism is poorly understood. We learned that the effect of desmopressin is not dependent on platelet associated von Willebrand factor and either not solely or not at all related to the multimeric size of the von Willebrand factor. Further mechanisms related to the endothelium are being examined.