Excitotoxicity in Circulatory Arrest ? Brain Injury

描述(申请人提供)：低温停循环(HCA)技术是一种公认的神经保护策略，可以对胸主动脉和先天性心脏畸形进行复杂的修复。尽管HCA在临床医学上有用，但它并不是没有明显的神经后遗症，包括智力和神经精神运动障碍、癫痫、舞蹈动作障碍、发育迟缓和中风。自1992年以来，在美国国立卫生研究院的持续支持下，我们的实验室完成了一项重要的工作，其中我们在临床相关的体外循环(CPB)和HCA模型中研究了神经损伤的机制。在我们的犬模型中，复制了心脏外科手术中的临床经验，在180℃下接受2小时HCA的狗保持了一致的神经功能缺陷和选择性神经元死亡的组织学模式。最近犬全基因组测序和犬类寡核苷酸芯片的发展为我们提供了一个独特的机会来研究HCA(包括长时间和短时间)以及标准的体外循环(CPB)后神经损伤的分子机制。我们目前的建议侧重于以下目标：1.)利用微阵列分析，描述由1和2小时的HCA和没有HCA 2的标准CBP引起的兴奋性毒性神经元损伤的潜在基因组调控。)确定一种新的治疗策略(丙戊酸)和3.基因表达的神经保护性变化。)目的：研究脑脊液(CSF)和血清中存在的基因产物(蛋白质)，以确定脑和/或神经元特异性蛋白质生物标志物，以诊断HCA和CPB的诊断和预后。为了帮助我们实现这些目标，除了我们之前与肯尼迪·克里格研究所的神经科学家合作外，我们还获得了来自约翰霍普金斯大学医疗机构(JHMI)微阵列核心设施、心脏病学部、病理学系和佛罗里达大学/Banyan Biomarkers的杰出多学科研究人员的帮助。我们相信，当我们在工作中追求这些令人振奋的新方向时，我们已经组建了一支具有广泛专业知识的团队来帮助我们。多学科的转化性研究是减少低温停循环患者神经损伤的基石。通过将基因组学和蛋白质组学的综合方法应用到我们的犬类HCA模型中，我们希望发现关于脑损伤机制的新见解，药物干预如何减轻这种损伤，以及我们如何即使在检查时很微小也能清楚地识别损伤。与公共卫生相关的各种原因引起的脑损伤是一个重大的国际卫生问题。本课题以心脏手术中常见的脑损伤(短期和长期应用低温停循环(HCA)和标准体外循环(CPB)，无HCA)为研究对象，旨在阐明其机制，开发用于诊断和预后的生物标志物，并探索有效的治疗方法。显然，将这项工作转化为临床实践不仅对那些患有HCA神经并发症的患者有好处，而且对接受常规心脏外科手术的患者以及因多种因素而遭受脑损伤的患者也有好处，例如中风、创伤性脑损伤或缺氧性脑损伤。

DESCRIPTION (provided by applicant): The technique of hypothermic circulatory arrest (HCA) is an established neuroprotective strategy allowing complex repairs of the thoracic aorta and congenital cardiac malformations. Despite its utility in clinical medicine, HCA is not without significant neurological sequelae which include intellectual and neuropsychomotor impairment, seizures, choreoathetosis, delayed development and stroke. Under continuous NIH support since 1992 our laboratory has completed an important body of work in which we have investigated the mechanisms of neurologic injury in a clinically relevant model of cardiopulmonary bypass (CPB) and HCA. In our canine model, which replicates clinical experience during cardiac surgical procedures, dogs subjected to two hours of HCA at 180C sustain a consistent neurologic deficit and histological pattern of selective neuronal death. The recent sequencing of the complete canine genome and the development of canine oligonucleotide microarrays has given us a unique opportunity to examine the molecular mechanisms of neurologic injury following HCA (both for prolonged and brief durations) as well as with standard cardiopulmonary bypass (CPB). Our current proposal focuses on the following objectives: 1.) To delineate, using microarray analysis, the underlying genomic regulation responsible for excitotoxic neuronal injury caused by 1 and 2 hours of HCA and standard CBP without HCA 2.) To identify neuroprotective changes in gene expression that result from a novel therapeutic strategy (Valproic acid) and 3.) To investigate gene-products (proteins) present in the cerebral spinal fluid (CSF) and serum for identification of brain and/or neuronal specific protein biomarkers for diagnosis and prognosis in HCA and CPB. To help us accomplish these goals, we have enlisted the help of an outstanding multidisciplinary group of investigators from the Johns Hopkins Medical Institutions (JHMI) Microarray Core Facility, Division of Cardiology, Department of Pathology and the University of Florida/Banyan Biomarkers; in addition to our previous collaboration with neuroscientists at the Kennedy Krieger Institute. We are confident that we have assembled a team with broad expertise to help us as we pursue these exciting new directions in our work. Multidisciplinary translational research is the cornerstone to reducing neurologic injury in patients undergoing hypothermic circulatory arrest. By applying an integrated approach of genomics and proteomics to our canine model of HCA, we hope to uncover new insights in the mechanisms of brain injury, how pharmacologic intervention attenuates that injury, and how we can clearly identify the injury, even when subtle on exam. PUBLIC HEALTH RELEVANCE Brain injury resulting from various causes is a significant international health concern. In this project, we focus on brain injury that occurs commonly in cardiac surgery (with both short and prolonged application of hypothermic circulatory arrest, HCA, and standard cardiopulmonary bypass, CPB, without HCA) in order to elucidate its mechanisms, develop biomarkers for diagnosis and prognosis, and discover effective therapies. Clearly, the translation of this work to clinical practice can have benefits not only for those patients with neurologic complications from HCA but also for patients undergoing routine cardiac surgical procedures and for those suffering brain injury from a number of factors, such as, stroke, traumatic brain injury or anoxic brain injury.