MACULAR BIOCHEMISTRY

视网膜相关性黄斑变性（AMD）是导致失明的主要原因 在美国老年人中。为什么中央（尤其是副中央） 人类视网膜上最容易受损的区域的基本假设 这个建议是，黄斑的独特性不仅要被发现， 在其不同寻常的解剖学上，也在其生物化学上，特别是在 保护剂的详细空间分布。次级 假设活跃生化过程可能是导致 视网膜抗氧化剂和其他化合物显示的特定模式 给予保护。 长期目标是提高我们的 了解黄斑生物化学及其与黄斑 退化重点将放在微量营养素，因为 可能性或预防性饮食干预。 具体目标是回答以下问题： l）黄斑色素类胡萝卜素、叶黄素 和玉米黄质，显示出对AMD的保护作用， 在灵长类动物（和人类）视网膜的中央凹区域积累了多少？我们 假设黄斑中特异性黄斑色素结合蛋白 是造成这种增长的原因 这些将被识别和隔离 通过追踪内源性配体的特征，可见的， 类胡萝卜素光谱 物理和配体结合性质将是 测定了部分氨基酸序列的测定将允许 与其他生物体的类胡萝卜素结合蛋白相比， 中央凹cDNA文库。 2)中位玉米黄质进入人体的机制是什么？ 黄斑中心凹还是黄斑色素它不在血液中。我们 假设在黄斑中有特定的转化酶， 把叶黄素变成这种立体异构体。如果是的话，它们的基质是什么 特异性、定位和作用机制？ 3)维生素E是一种有效的膜抗氧化剂， 猴神经视网膜中的浓度，在放射状位置， 中央凹脊就在中央凹外面是否存在类似的最小值， 图或维生素E在人类视网膜？这种生物化学的重要性 弱点在于观察到它的位置会与 地图状萎缩的初始位置--常见的“干燥”形式 或者是威胁视力的老年黄斑变性 4)其他存在于细胞膜和可溶性隔室中的抗氧化剂 或灵长类动物和人类的视网膜，补偿（或可能加剧） 视网膜中央凹嵴缺乏维生素E先前的研究 缺乏详细的抗氧化剂地图的空间分辨率。径向 维生素C，谷胱甘肽，泛醇和胆红素的分布将是 考察 这些项目的方法是分析生物化学， 主要是HPLC分离和分析。 此外，目标1要求 合作的分子生物学技术，目标2涉及短- 术语组织培养。

Age-related macular degeneration (AMD) is the leading cause of blindness among older Americans. Why is the central (especially the parafoveal) region of the human retina so prone to damage? The basic hypothesis of this proposal is that the uniqueness of the macula is to be found not only in its unusual anatomy but also in its biochemistry, particularly in the detailed spatial distributions of protective agents. A secondary hypothesis that active biochemical proc~ may be responsible for the specific patterns displayed by retinal antioxidants and by other compounds conferring protection. The long-term goal is to increase our understanding of macular biochemistry and how it relates to macular degeneration. Focus will be placed on micronutrients, because of the possibility or preventive dietary intervention. Specific Aims are to answer the following questions: l) What is the mechanism by which the macular-pigment carotenoids, lutein and zeaxanthin, shown to be protective against AMD, are selectively accumulated in the foveal region of the primate (and human) retina? We hypothesize that specific macular pigment-binding proteins in the macula are responsible for this accretion. These will be identified and isolated through tracking endogenous ligands by their characteristic, visible, carotenoid spectra. Physical and ligand-binding properties will be measured. Determination of partial amino-acid sequences will allow comparison to carotenoid-binding proteins of other organisms, and also to foveal cDNA libraries. 2) What is the mechanism by which meso-zeaxanthin comes to be in the human fovea as part Or the macular pigment? It is not in the blood. We hypothesize that there are specific converting enzymes in the macula that change lutein into this stereoisomer. If so, what are their substrate specificities, localizations, and mechanisms of action? 3) Vitamin E, a potent membrane antioxidant, displays a dramatic dip in concentration in the monkey neural retina, at the radial position of the foveal crest, just outside the fovea. Does a similar minimum exist in a map Or vitamin E in the human retina? The importance Or such a biochemical vulnerability lies in the observation that its position would coincide with the initial location of geographic atrophy -- the common, "dry" form Or sight-threatening AMD. 4) Do other antioxidants, present in membranes and in soluble compartments Or the primate and human retina, compensate for (or perhaps exacerbate) the deficiency of vitamin E at the foveal crest? Previous studies have lacked the spatial resolution for a detailed antioxidant map. The radial distributions of vitamin C, glutathione, ubiquinols, and bilirubin will be examined. The methodology for these projects is that of analytical biochemistry, chiefly HPLC separations and analyses. In addition, Aim 1 will require collaborations for molecular-biology techniques, and Aim 2 involves short- term tissue culture.