OXYGEN AND LIGHT DEPENDENCY OF PHOTODYNAMIC THERAPY

光动力疗法(PDT)的疗效取决于同步的 肿瘤组织中存在光敏剂、氧气和光线。因素 限制这两个参数中的任何一个都会限制PDT。一个这样的限制 因素可能是低氧肿瘤细胞区域的存在，这可能是 由于肿瘤供血不足，在PDT之前出现，或者可能是 由于严重的血管损伤，在肿瘤照射期间早期产生 由PDT诱导。另一个可能的限制因素是 伴有PDT的血管损伤的出血可能会限制 在将完全有效的光剂量传递到 肿瘤细胞。建议审查以下问题的范围和意义 这些对体内PDT治疗的限制。 光动力疗法的氧依赖性将在细胞内确定。 在体内卟啉摄取条件下获得的卟啉浓度。 预先存在的低氧肿瘤细胞区对IN的可能影响 将检查活体光动力疗法。血管光动力损伤对肿瘤的影响 氧合作用与急性缺氧区的可能形成 将对光传输技术进行研究。如果有肿瘤的话就要检查 PDT后发生复氧。 光动力疗法中皮肤和肿瘤组织的光穿透变化 将被监测，并将测量由于出血造成的光损失。 载氧增强肿瘤氧合作用的可能性 化学物质和高氧呼吸可能会增强光动力肿瘤 将对销毁进行研究。

The effectiveness of photodynamic therapy (PDT) depends on the simultaneous presence in the tumor tissue of photosensitizer, oxygen and light. Factors restricting either of these parameters will limit PDT. One such limiting factor may be the existence of hypoxic tumor cell regions, which may be present prior to PDT due to poor tumor blood supply, or which may be created early during tumor illumination due to the severe vascular damage induced by PDT. Another possibly limiting factor is the development of hemorrhage accompanying PDT-induced vascular damage which may restrict light penetration before a fully effective light dose has been delivered to the tumor cells. It is proposed to examine the extent and significance of these limitations to PDT treatment in vivo. The oxygen dependency of PDT treatment will be determined at cellular prophyrin concentrations obtained under in vivo porphyrin uptake conditions. The possible influence of pre-existing hypoxic tumor cell regions on in vivo PDT will be examined. The effect of vascular PDT damage on tumor oxygenation and the possible creation of acutely hypoxic tumor areas during PDT light delivery will be studied. It will be examined if tumor reoxygenation occurs following PDT. The changes in light penetration through skin and tumor tissue during PDT will be monitored, and light loss due to hemorrhage will be measured. The possibility that enhancement of tumor oxygenation by oxygen-carrying chemicals and high oxygen breathing may enhance photodynamic tumor destruction will be studied.