MACULAR BIOCHEMISTRY

老年性黄斑变性(AMD)是导致失明的主要原因 在年长的美国人中。为什么中央(尤其是副中凹) 人类视网膜的区域如此容易受损？的基本假设 这一建议是，不仅要发现黄斑的独特性 在它不同寻常的解剖结构上，也在它的生物化学上，特别是在 保护剂的详细空间分布。次要的 假设活跃的生化过程可能是导致 视网膜抗氧化剂和其他化合物所显示的特定模式 授予保护。我们的长期目标是增加我们的 了解黄斑生物化学及其与黄斑的关系 退化。将把重点放在微量营养素上，因为 预防性饮食干预的可能性。 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，被证明对AMD有保护作用，是选择性的 聚集在灵长类(和人类)视网膜的中心凹区域？我们 假设黄斑中特定的黄斑色素结合蛋白 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， 类胡萝卜素光谱。物理和配体结合性质将是 量过了。对部分氨基酸序列的测定将使 与其他生物的类胡萝卜素结合蛋白的比较，以及 小凹cDNA文库。 2)中玉米黄质进入人体的机制是什么？ 黄斑中心凹是黄斑色素的一部分？这不是血液中的东西。我们 假设在黄斑中有特定的转换酶 把叶黄素变成这种立体异构体。如果是，它们的底物是什么？ 具体的、本地化的和作用机制？ 3)维生素E，一种有效的膜抗氧化剂，表现出显著的下降 集中在猴子神经视网膜的放射状位置 中心凹，就在中心凹外面。是否存在类似的最低要求 人类视网膜中的MAP或维生素E？这样的生物化学的重要性 脆弱性在于观察到它的位置会重合 伴随着地理萎缩的初始位置--常见的“干燥”形式 或者会影响视力的老年性黄斑变性。 4)膜和可溶性隔间中是否存在其他抗氧化剂 或灵长类动物和人类的视网膜，弥补(或可能加剧) 黄斑顶区维生素E缺乏？之前的研究已经 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、泛喹醇和胆红素的分布情况如下 检查过了。 这些项目的方法是分析生物化学， 主要是高效液相色谱分离分析。此外，目标1将要求 分子生物学技术的合作，目标2涉及简短- 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.