PHOTODYNAMICS OF ULTRAVIOLET EPIDERMAL CHROMOPHORES

描述：(改编自申请者的摘要)压倒性 有证据表明，过度暴露在太阳紫外线(UV)下 辐射抑制免疫反应，从而促进肿瘤 生长和患皮肤癌的风险。暴露在紫外线辐射中也 在皮肤中引起各种组织学反应，包括增加 在弹性纤维中取代真皮基质中的胶原蛋白， 糖胺多聚糖、胶原交联剂和表皮的增加 变厚了。这些过程始于皮肤中的天然发色团 吸收太阳辐射。这份提案描述了一个研究项目 旨在研究两种表皮发色团的光反应性 尿毒酸和黑色素。该项目的具体目标是：(A) 测定单线态产生的体外作用谱 反式尿毒酸激发后的分子氧 确定此测得的动作谱是否与 任何已报道的不同组织学的体内作用谱 皮肤对紫外线照射的反应，(B)开发一个综合模型 对于顺式分子的光谱和波长相关的光反应性- 尿毒酸及其各种成分的作用光谱测定 光化学过程，(C)开发一个全面的模型， 合成黑色素和天然黑色素的光谱和光化学，以及 (D)研究与黑色素结合的药物分子如何影响 药物和色素的光动力学。

DESCRIPTION: (Adapted from the applicant's abstract) Overwhelming evidence indicates that excess exposure to the sun's ultraviolet (UV) radiation suppresses the immune responses, which can promote tumor growth and the risk of skin cancer. Exposure to UV radiation also causes a variety of histological responses in skin including an increase in elastic fibers replacing the collagen in the dermal matrix, an increase in glycosaminoglycans, collagen cross-linking, and epidermal thickening. These processes begin when natural chromophores in skin absorb solar radiation. This proposal describes a research program directed at studying the photoreactivity of two epidermal chromophores urocanic acid and melanin. The specific goals of the project are (a) to measure the in vitro action spectrum for the generation of singlet molecular oxygen following the excitation of trans-urocanic acid and to determine if this measured action spectrum quantitatively agrees with any of the reported in vivo action spectra for various histological responses of skin to UV exposure, (b) to develop a comprehensive model for the spectroscopy and wavelength-dependent photoreactivity of cis- urocanic acid and to determine action spectra for its various photochemical processes, (c) to develop a comprehensive model for the spectroscopy and photochemistry of synthetic and natural melanins, and (d) to study how drug molecules bound to melanin affect the photodynamics of both the drug and pigment.