Point-of Care System for Determination of Bilirubin Capacity in Neonates

说明(申请人提供)：人血清白蛋白能够以高亲和力结合胆红素，从而隔离胆红素，减轻其对患有黄疸的新生儿的不良神经影响。尽管大量研究表明，血液中胆红素相对于白蛋白结合部位的水平是评估胆红素相关性脑损伤风险的关键因素，但新生儿黄疸的管理仍然基于替代指标，如胎龄和出生体重以及胆红素水平。目前已有多种测定胆红素水平的方法。测定血清总胆红素的常用方法是湿化学法。多年来，人们发展了测定血清中储备白蛋白结合力和游离胆红素水平的方法，但由于实验室测试仍然繁琐，没有一种方法能够实现常规使用。提出的工作是开发一种利用Bili-Rubin的天然荧光的护理点系统(一个小型荧光计和一次性设备)。胆红素与白蛋白结合会产生一种可以在原始血液中检测到的荧光信号。用荧光法测定白蛋白结合胆红素水平相当于用标准方法测定的血清总胆红素水平，因为在白蛋白结合接近饱和之前，未结合胆红素水平总是低得多。胆红素的储备结合能力可以通过向血液中加入过量的胆红素来测量，荧光的增加是由于新结合的胆红素。这种方法测量实际结合能力，并自然考虑白蛋白水平、其他溶质竞争结合和弱化结合位点等因素。导致这种荧光方法的基础研究是在30多年前报道的，实验室里的原型仪器已经设计出来，并在临床环境中进行了测试。当时，在没有绑定数据的情况下，新的管理指南加上光疗的广泛使用，排除了它们的使用。由于目前的做法是非常早地释放看似健康的新生儿，以及随后在家中出现黄疸，管理变得复杂起来。与“实地”儿科医生的访谈表明，一种廉价、易用、只需要“脚后跟”输血量且基本上不需要对标本进行操作的护理点系统将提供更好的管理，因为它能够单独提供一个稳定的胆红素水平，而有约束力的数据还将为管理提供可能更有效率和更低成本的指导。在婴儿床边使用也有利于对有黄褐症住院的低出生体重和患病新生儿的管理。虽然现代光电子技术显然是可行的，但要开发这样一个小型护理系统，存在几个设计和实际挑战。拟议的工作将面对并克服这些挑战。 公共卫生相关性：核黄体症是一种可预防的新生儿脑损伤，在美国重新出现(1-5例)。目前的胆红素测定方法没有考虑到儿童安全地隔离胆红素的能力，必须从胎龄、年龄、体重和其他因素来解释(6)。建议的血液荧光仪直接测量胆红素结合量和储备胆红素结合量，具有更快、更便宜和在护理点可用的潜力。

DESCRIPTION (provided by applicant): Human serum albumin is capable of binding bilirubin with high affinity, thus sequestering it and mitigat- ing its harmful neurological effects in jaundiced newborns. Despite considerable work indicating that the level of bilirubin in the blood relative to the level of albumin binding sites is a key factor in assessing risk for bilirubin associated brain damage, management of neonatal jaundice remains based upon proxies, such as gestational age and birth weight along with the bilirubin level. A number of methods for assaying the bilirubin level now ex- ist. The common approaches determine the total serum bilirubin by wet chemical methods. Methods to assay reserve albumin binding capacity and unbound (mobilized) bilirubin levels in serum have been developed over the years but none have achieved routine use because they remain cumbersome laboratory tests. The pro- posed work is to develop a point-of-care system (a small fluorometer and disposables) that makes use of bili- rubin's natural fluorescence. Bilirubin bound to albumin produces a fluorescence signal that can be detected in raw blood. Assayed by fluorescence this albumin-bound bilirubin level equates to the total serum bilirubin by standard methods since the unbound bilirubin level is always much smaller until albumin binding approaches saturation. The reserve binding capacity for bilirubin can be measured by adding excess bilirubin to the blood, with the increase in fluorescence being due to the newly bound bilirubin. This approach measures the actual binding capacity and naturally takes into account factors such as albumin levels, competing binding by other solutes and weakened binding sites. The basic studies leading to this fluorometric approach were reported more than thirty years ago and prototype laboratory-bound instruments were devised and tested in clinical settings. At that time new manage- ment guidelines in the absence of binding data coupled with wide use of phototherapy obviated their use. With the current practice of very early release of apparently healthy newborns and susbsequent development of jaundice at home, management has become complicated. Interviews with pediatricians "on the ground" have indicated that an inexpensive and easy to use point-of-care system that requires only a "heel stick" quantity of blood and essentially no manipulation of the specimen, would provide for better management from the ability to provide a stat bilirubin level alone, and binding data would additionally provide guidance in management that may be more efficient and less costly. Use at crib-side should also benefit the management of the jaundiced hospitalized low-birth-weight and sick neonate. While apparently feasible with modern optoelectronic technology, several design and practical chal- lenges exist for the development of such a small point-of-care system. The proposed work will confront and overcome these challenges. PUBLIC HEALTH RELEVANCE: Kernicterus is a preventable brain injury in neonates, and it is reemerging in the USA (1-5). Present-day methods of assaying bilirubin do not take into account a child's ability to safely sequester bilirubin and must be interpreted in terms of gestational age, age, weight and other factors (6). The proposed hematofluorometer directly measures bilirubin binding and reserve bilirubin binding capacity, and has the potentials to be faster, less expensive and available at the point of care.