DEVELOPMENT OF A NOVEL WHOLE BLOOD COAGULATION ASSAY

本子项目是利用由NIH/NCRR资助的中心赠款提供的资源的众多研究子项目之一。子项目和研究者（PI）可能已经从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。列出的机构是中心的，不一定是研究者的机构。在过去的40年里，我们对血液凝固的认识发生了重大变化。新的、更有效的抗血小板和抗凝药物已经被引入。尽管药物治疗的创新，我们的标准实验室止血分析不能反映我们对凝血机制的新见解，也不能作为这些新药的足够的实验室监测。目前的临床实验室检测是对不含血小板的血浆样本进行的。越来越明显的是，全血是分析凝血最合适的患者样本。该止血分析系统（H.A.S.）分析全血样本使用定量物理技术。先前的研究表明，has测量的参数不仅反映了血凝块的结构质量，还反映了血凝块形成过程中的血小板功能。H.A.S.是第一个在凝块形成过程中定量评估血小板功能的体外系统。由于最近引入了非常有效的抗血小板和抗凝药物，监测其效果的能力变得越来越重要。这些强效药物在疗效和毒性之间的治疗窗口非常狭窄。虽然它们能有效控制高凝条件下的血栓形成，但它们的相对效力会增加大出血的风险。不幸的是，传统的监测参数（即PT、aPTT、INR）不能测量或预测疗效或毒性。因此，临床医生不能充分（或安全地）监测这些新药治疗的安全性或有效性。虽然一些抗凝剂（如低分子肝素）的常规监测在正常患者中可能没有必要，但记录足够和安全的临床反应对于并发出血危险因素的复杂患者（如肝肾功能障碍患者）至关重要。我们在终末期肾病（ESRD）受试者中进行了令人信服的初步数据，显示暴露于低分子肝素依诺肝素后抗凝反应增强。对于这些特殊人群，临床医生迫切需要一种廉价的检测方法，可以快速测量疗效并预测毒性风险。我们相信H.A.S.可以发挥这一作用，并改善对这些特殊凝血障碍人群的护理。通过这样做，这将允许临床医生定制抗凝治疗，以获得成功的结果，同时防止不良出血事件。这些结果将降低医疗成本。这项研究有两个具体目的。第一种方法是使用haemdyne止血分析系统，在两组受试者中确定增加依诺肝素剂量（0.25、0.50和1.0 mg/kg）后，抗Xa因子活性与凝血酶生成时间（TGT）的体内关系：1)没有肾功能障碍的正常健康受试者；2)接受维持性血液透析的终末期肾病（ESRD；肌酐清除率< 10 mL/min）患者。第二个目标是确定血红素止血分析系统在单剂量依诺肝素1mg /kg后12小时内凝血酶生成时间组间（对照与ESRD）差异的能力。所有以前和现在的血小板功能测量都必须与凝血一起进行，通过表征这些重要的凝血参数，H.A.S.是一种灵敏、新颖的全血检测，可监测各种疾病状态和抗凝治疗患者的凝血状态。

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. Over the last 40 years, our understanding of blood coagulation has changed significantly. Newer, more potent antiplatelet and anticoagulant medications have been introduced. Despite the innovation of drug therapy, our standard laboratory assays of hemostasis do not reflect our new insights into the clotting mechanism, and do not serve as adequate laboratory monitors for these new drugs. Current clinical laboratory assays are performed on plasma samples that do not contain platelets. It is becoming increasingly apparent that whole blood is the most appropriate patient sample for analyzing coagulation. The Hemodyne Hemostasis Analysis System (H.A.S.) analyzes whole blood samples using quantitative physical techniques. Previous investigations have shown that the parameters measured by the H.A.S. reflect not only the structural qualities of the blood clot, but also platelet function during clot formation. The H.A.S. is the first ex vivo system to quantitatively assess platelet function during clot formation. Due to the recent introduction of very potent antiplatelet and anticoagulant medications, the ability to monitor their effects is increasingly important. These potent drugs have a very narrow therapeutic window between efficacy and toxicity. Although they effectively control thrombosis in hypercoagulable conditions, their relative potency increases the risk of major hemorrhage. Unfortunately conventional monitoring parameters (i.e., PT, aPTT, INR) cannot measure or predict efficacy or toxicity. Thus, clinicians cannot adequately (or safely) monitor these new drug therapies for safety or efficacy. While the routine monitoring of some anticoagulants (such as low molecular weight heparin (LMWH)) may not be necessary in normal patients, the importance of documenting adequate and safe clinical response is critical in complex patients with concurrent risk factors for hemorrhage (e.g., patients with hepatic or renal dysfunction). We have compelling preliminary data conducted in end-stage renal disease (ESRD) subjects that demonstrate an enhanced anticoagulant response following exposure to the LMWH enoxaparin. For these special populations, clinicians desperately need an inexpensive assay that can quickly measure efficacy and predict risk of toxicity. We believe the H.A.S. can serve this role, and improve the care to these special populations with coagulation disorders. By doing so, this would allow clinicians to tailor anticoagulant therapy to achieve successful outcomes while preventing adverse bleeding events. These outcomes should result in reduced healthcare costs. This study has two specific aims. The first involves using the Hemodyne Hemostasis Analysis System , to define the in vivo relationship of antifactor Xa activity to thrombin generation time (TGT) following increasing doses of enoxaparin (0.25, 0.50 and 1.0 mg/kg) in two groups of subjects: 1) normal, healthy subjects without renal dysfunction; and 2) subjects with end-stage renal disease (ESRD; creatinine clearance < 10 mL/min) on maintenance hemodialysis. The second goal is to determine the ability of the Hemodyne Hemostasis Analysis System to characterize intergroup (control versus ESRD) differences in thrombin generation time over 12 hours following single dose enoxaparin 1 mg/kg. All previous and current measures of platelet function must be performed with clotting by characterizing these important clotting parameters, the H.A.S. is a sensitive, novel, whole blood assay that monitors coagulation status in various disease states and in patients on anticoagulant therapy.