ACTION OF DMSA ON CELLULAR LEAD METABOLISM AND TOXICITY

铅中毒是儿科最常见的可预防疾病。 今天在美国的年龄段。在1988年提交给国会的报告中， 美国公共卫生服务估计，500万或更多的年幼儿童 所有来源的铅都有很高的风险，包括食物，饮用水， 灰尘，泥土，汽油，还有油漆。不幸的是，这种疾病会 持续很多年，因为仍然有4000多万套住房 在全国范围内，含有有害数量的含铅油漆。 许多研究都研究了络合剂对铅的作用。 动物和人类的新陈代谢，包括选择性地从软组织中清除 组织和骨骼，以及改变的金属螯合剂的组织沉积 复合体。衡量螯合剂有效性的最关键的指标(S)是 有能力(A)减少细胞铅负担，(B)恢复或防止铅- 导致细胞功能丧失，以及(C)不会产生不良影响 干扰人体动态平衡和必需微量元素的利用。 目前对Meso-2，3-的作用知之甚少。 二硫代丁二酸(DMSA)，一种孤儿螯合药物，对细胞铅的作用 新陈代谢。此应用程序中要解决的问题包括，如何 必须去除大量的铅，以及从哪个亚细胞动力学池中 提供生化功能的恢复(卟啉、血红素和 骨钙素的产生)对细胞有何影响？总而言之，这些实验将 验证DMSA将降低铅在体内的细胞负荷的假设 在动力学上不同的细胞内动力学池中的关键目标 铅，而这些池中铅含量的减少会导致 选择性地恢复细胞功能。这些实验将会进行 培养的肾近端小管细胞和克隆性成骨细胞 骨细胞(ROS 17/2.8)。三个具体目标是： 1.表征和比较DMSA降低细胞毒性的能力 通过评价DMSA对稳态的作用来评价铅的负荷 ~(210)Pb在培养的肾小管和成骨细胞中的动力学 2.描述DMSA增加Pb2进入 通过评价210Pb2+细胞的稳态动力学 210Pb-DMSA复合体，在培养的肾小管和成骨细胞中表达。 3.描述DMSA恢复铅细胞功能的能力 通过评价卟啉对染毒细胞的修复作用 肾小管和成骨细胞产生的血红蛋白，以及 成骨细胞产生骨钙素的恢复。 总而言之，本项目将描述DMSA减少 铅在两个重要靶细胞中的亚细胞负荷 用~(210)Pb代谢动力学模型研究毒性及其相关性 三种重要生化指标对细胞内铅代谢的影响 以及铅中毒的临床检测方法。这些研究将(A)有助于 要了解螯合剂作用的基本机制和过程，请参阅 细胞一级，(B)为设计更有效和更有效的 更安全的螯合药物，以及(C)在以下方面提供了一种联系： 细胞水平与临床和动物研究。

Lead (Pb) toxicity is the most common preventable disease in the pediatric age group today in the United States. In its 1988 report to Congress, the U.S. Public Health Service estimated that 5 million or more young children are at high risk from all sources of Pb, including food, drinking water, dust, dirt and gasoline, and paint. Unfortunately, this disease will continue for many years, because there are still over 40 million dwellings nationally that contain hazardous quantities of leaded paint. Numerous studies have investigated the actions of chelating agents on lead metabolism in animals and humans, including selective removal from soft tissues and the skeleton, and altered tissue deposition of metal-chelator complexes. The most critical measure(s) of chelator efficacy are the ability to (a) reduce cellular lead burden, (b) restore or prevent Pb- induced loss of cell function, and (c) not produce adverse effects by interfering with homeostasis and utilization of essential trace elements. Little is currently known regarding the action of meso-2,3- dimercaptosuccinic acid (DMSA), an orphan chelating drug, on cellular lead metabolism. The questions to be addressed in this application include, How much lead must be removed, and from which subcellular kinetic pool, to provide restoration of biochemical function (porphyrin, heme, and osteocalcin production) to the cells? together, these experiments will test the hypothesis that DMSA will decrease the cellular burden of lead in critical target within kinetically distinct intracellular kinetic pools of lead, and that reduction the amount of lead in these pools leads to a selective restoration of cell function. The experiments will be conducted in cultured renal proximal tubule cells (PCT) and in clonal osteoblastic bone cells (ROS 17/2.8). Three specific aims are to: 1. Characterize and compare the ability of DMSA to reduce the cellular burden of lead by evaluating the action of DMSA on the steady state kinetics of 210Pb in cultured renal tubule and osteoblastic bone cells. 2. Characterize the potential for DMSA to increase movement of Pb2+ into cells by evaluating the steady state kinetics of 210Pb administered as the 210Pb-DMSA complex, in cultured renal tubule and osteoblastic bone cells. 3. Characterize the ability of DMSA to restore cellular function in lead intoxicated cells by evaluating the restoration of porphyrin and hemoprotein production in renal tubule and osteoblastic bone cells, and the recovery of osteocalcin production in osteoblasts. In summary, this project will characterize the ability of DMSA to reduce the subcellular burden of lead in two important target cells for lead toxicity using a kinetic model for 210Pb metabolism and correlate these changes in intracellular lead metabolism with three important biochemical and clinical measures of lead toxicity. These studies will (a) contribute to understanding the basic mechanisms and processes of chelator action at the cellular level, (b) provide a basis for designing more effective and safer chelating drugs, and (c) provide a link between chelator action at the cellular level with clinical and animal studies.