Hogikyan N D, Hayden R E, McLear P W
Department of Otolaryngology--Head and Neck Surgery, Washington University School of Medicine, MO 63110.
Am J Otolaryngol. 1991 Jan-Feb;12(1):1-5. doi: 10.1016/0196-0709(91)90066-o.
Photodynamic therapy (PDT) is emerging as an effective therapy for a variety of malignant diseases, including head and neck cancer. Prolonged cutaneous photosensitivity following therapy, however, remains the most significant side effect. The biochemical mechanism of this sensitivity, and indeed of the tumoricidal effect of PDT, is uncertain, but is believed to involve formation of singlet oxygen and possibly other oxygen-derived free radicals. This laboratory recently reported that a singlet oxygen scavenger, diphenylisobenzofuran (DPIBF), afforded cutaneous photoprotection to 67% of animals treated with PDT. Those results, the first from an in vivo study, supported the idea that singlet oxygen plays a significant role in PDT and its associated toxicity. They also, however, suggested that it is not the sole intermediate. The current study looks at the photoprotective effects of the hydroxyl radical scavenger dimethyl thiourea, alone and in conjunction with DPIBF. Our results strongly support a role for the hydroxyl radical in producing the cutaneous phototoxicity associated with PDT.
光动力疗法（PDT）正逐渐成为治疗包括头颈癌在内的多种恶性疾病的有效疗法。然而，治疗后皮肤光敏性延长仍是最主要的副作用。这种光敏性以及PDT的肿瘤杀伤作用的生化机制尚不确定，但据信涉及单线态氧以及可能其他氧衍生自由基的形成。本实验室最近报告称，单线态氧清除剂二苯基异苯并呋喃（DPIBF）为67%接受PDT治疗的动物提供了皮肤光保护。这些结果是首次来自体内研究，支持了单线态氧在PDT及其相关毒性中起重要作用的观点。然而，它们也表明单线态氧并非唯一的中间产物。当前的研究考察了羟基自由基清除剂二甲基硫脲单独以及与DPIBF联合使用时的光保护作用。我们的结果有力地支持了羟基自由基在产生与PDT相关的皮肤光毒性中所起的作用。
