LASER MICROPROBE ANALYSIS OF NEURONAL MERCURY

肌萎缩侧索硬化症的病因学 以选择性运动死亡为特征的退行性疾病 神经元，是未知的。PI之前的研究表明， 与对照组相比，肌萎缩侧索硬化症组织中汞含量大幅增加， 支持有毒金属可能致病的假说 在肌萎缩侧索硬化症。然而，这一假设仍然是相当投机的。 因为有毒金属的细胞分布还没有 调查以确定汞是否实际上是有选择性的 富含运动神经元。 在拟议的研究中，激光激活的微探针质量分析 (南丫岛)将被用来测量汞的丰度和 运动神经元中的其他元素。南丫岛是一种新技术， 能够探测单个细胞的特定区域和 用空间元素分析确定完整的元素组成 分辨率为1-2微米。肌萎缩侧索硬化症的脑和脊髓 将获得年龄匹配的对照；已知的地区是 ALS(运动皮质、腹侧脊髓)的病理参与 将使用南丫大学进行分析。在对照组中，汞的丰度 会在运动神经元的胞核和胞浆中被检测到 与其他细胞进行比较，以检验汞是 运动神经元选择性地堆积。在ALS中，特别是 我们将关注不同阶段的运动神经元 退行性变包括近端轴突球体的分析 确定神经元汞蓄积是否先于汞蓄积，或者是 神经元死亡的后果。汞的化验将在 OnuFrowicz核(支配膀胱的运动神经元； 在ALS中幸免于难)以确定这些细胞是否不同于易感 脊髓运动神经元与其毒性负荷的关系 金属。将在ALS和对照之间进行比较 基于逐个区域和逐个单元格类型来确定是否 肌萎缩侧索硬化症患者汞的相对丰度增加。散装 来自相同患者的组织样本将被分析为 中子活化将南丫岛数据直接与之前的 由PI和其他人进行的研究。尽管工作的主要重点是 水银、南丫岛和中子活化是否都能提供 同时分析其他人假设的多种元素 参与肌萎缩侧索硬化症的发病机制(例如：铅、铝、 硒)。 这项研究的结果将提供第一次测量 散发性肌萎缩侧索硬化症患者运动神经元中汞的丰度。 这些分析将直接检验这一假设 脊髓运动神经元中汞的积累标志着细胞 容易发生肌萎缩侧索硬化症类型的退化。

The etiology of amyotrophic lateral sclerosis (ALS), a degenerative disorder characterized by selective death of motor neurons, is unknown. Prior studies by the PI have demonstrated large increases in mercury in ALS tissues compared to controls, supporting the hypothesis that toxic metals may be pathogenetic in ALS. However the hypothesis remains quite speculative because the cellular distribution of toxic metals has not been investigated to determine if mercury is, in fact, selectively enriched in motor neurons. In the proposed study, Laser Activated Microprobe Mass Analysis (LAMMA) will be used to measure the abundances of mercury and other elements in motor neurons. LAMMA is a new technique, capable of probing specific regions of individual cells and determining the complete elemental composition with a spatial resolution of 1-2 microns. The brain and spinal cord of ALS and age-matched controls will be obtained; regions known to be pathologically involved in ALS (motor cortex, ventral spinal cord) will be analyzed using LAMMA. In controls, mercury abundance will be assayed in the nucleus and cytoplasm of motor neurons and compared to other cells to test the hypothesis that mercury is selectively accumulated by motor neurons. In ALS, particular attention will be directed to motor neurons in various stages of degeneration including analysis of proximal axonal spheroids to determine if neuronal mercury accumulation preceeds, or is a consequence of, neuronal death. Mercury will be assayed in the Onufrowicz nucleus (motor neurons innervating the bladder; spared in ALS) to determine if these cells differ from susceptible motor neurons in the cord with regard to their burden of toxic metals. Comparisons will be made between ALS and controls on a region-by-region and cell type-by-cell type basis to establish if the relative abundance of mercury is increased in ALS. Bulk tissue samples from the same patients will be analyzed using neutron activation to relate the LAMMA data directly to previous studies by the PI and others. Although the primary focus of work is mercury, both LAMMA and neutron activation provide simultaneous analysis of multiple elements postulated by others to be involved in the pathogenesis of ALS (eg: lead, aluminum, selenium). The results of this study will provide the first measurement of mercury abundances in motor neurons of sporadic cases of ALS. These analyses will provide a direct test of the hypothesis that mercury accumulation in spinal motor neurons marks the cell as susceptible for ALS-type degeneration to occur.