BILIRUBIN ENCEPHALOPATHY--MODELS AND METABOLIC STUDIES

本提案的主要目的是发展候选人的 基础研究的技能，同时深入了解病理生理学， 核黄疸和胆红素毒性的机制。 通过课程， 讨论和监督调查，将获得理解， 细胞代谢和生理学水平，特别适合于 胚胎学和发育生物学的临床研究者。 本提案的科学目标是了解 仍不清楚潜在的细胞损伤基本核黄疸。 核黄疸，虽然主要与胎儿成红细胞增多症有关 以前，在15 - 25%的新生儿尸检中发现了这种情况。 的 核黄疸的发展不仅取决于血清中 未结合胆红素;与白蛋白明显结合， 血脑屏障是影响胆红素的至少两个缓解因素 损伤 已经开发了先前的模型来确定 核黄疸的特征性组织病理学和行为学变化。 然而，包括我们自己在内的先前研究表明， 模型仅产生短暂的胆红素脑病（TBE）， 动物 在体外，胆红素已被证明对许多细胞毒性， 许多不同类型的细胞的功能。 哪种毒性 在核黄疸中占主导地位是已知的;确定这取决于 在体内和体内都证实了相当的生理功能障碍， 体外模型 这项拟议的研究计划最初开发和表征不同的 核黄疸动物模型，包括溶血诱导模型 模拟与核黄疸相关的溶血条件。 组织学和行为学观察将确定核黄疸损伤。 核黄疸损伤的特点是神经生理学，磁 共振成像和光谱学研究，包括能量评估 新陈代谢的变化。 利用这些生理和代谢标记， 核黄疸和TBE之间的相似性和区别将被研究。 体内研究还将检查降低胆红素的疗法 生产和防止核黄疸的能力。 体外研究将进一步评估胆红素对神经源性 细胞 能量代谢的磁共振波谱研究将 允许与核黄疸的体内动物模型直接比较， 大脑能量代谢的变化。 这将 有助于验证该模型用于胆红素的进一步研究 毒性 后续研究将评估细胞环境，包括 pH值和白蛋白浓度，因为它会影响胆红素毒性，在这些 细胞 最后，胆红素毒性的研究将包括测定 对离子通道的膜生理学的影响。 这些渠道都很好- 特征在于神经母细胞瘤细胞，但不受胆红素的影响。 如果 必要时，计划应急开发替代细胞系， 胆红素毒性的体外研究。

The prime objective of this proposal is to development of the candidate's skills in basic research while gaining insight into the pathophysiology and mechanisms of kernicterus and bilirubin toxicity. By coursework, discussions and supervised investigation, understanding will be gained in cellular metabolism and physiology at a level particularly appropriate for a clinical investigator in neonatology and developmental biology. The scientific objective of this proposal is aimed at understanding the still obscure underlying cellular injuries fundamental kernicterus. Kernicterus, although primarily associated with erythroblastosis fetalis previously, has been found in 15-25% of autopsied newborns. The development of kernicterus depends on not only on serum level of unconjugated bilirubin; apparently binding to albumin and integrity of the blood-brain barrier are at least two mitigating factors affecting bilirubin injury. Prior models have been developed to determine what are the characteristic histopathologic and behavioral changes of kernicterus. However, previous studies including our own have shown that some of these models produce only a transient bilirubin encephalopathy (TBE) in these animals. In vitro, bilirubin has been shown to be toxic to many cellular functions of many different types of cells. Which of these toxicities predominates in kernicterus is known; determining this depends upon demonstration of comparable physiologic dysfunction in both in vivo and in vitro models. This proposed research plan initially develops and characterizes different animal models of kernicterus, including a hemolysis-induced model simulating hemolytic conditions associated with kernicterus. Histopathology and behavioral observations will define kernicterus injury. Kernicterus injury will then be characterized by neurophysiology, magnetic resonance imaging and spectroscopy studies, including evaluation of energy metabolism changes. Using these physiologic and metabolic markers, similarities and distinction between kernicterus and TBE will be studied. In vivo studies will also examine therapies to decrease bilirubin production and their ability to prevent kernicterus. In vitro studies will further evaluate bilirubin toxicity on neural-derived cells. Magnetic resonance spectroscopy studies of energy metabolism will allow direct comparison to in vivo animal models of kernicterus and the brain energy metabolism changes seen by our planned studies. This will help validate the use of this model for further studies of bilirubin toxicity. Subsequent studies will evaluate cellular environment including pH and albumin concentration, as it affects bilirubin toxicity in these cells. Finally, investigation of bilirubin toxicity will include assaying effects on membrane physiology of ion channels. These channels are well- characterize in neuroblastoma cells but not as affected by bilirubin. If necessary, contingencies are planned to develop alternate cell lines for in vitro studies of bilirubin toxicity.