OXYGEN AND LIGHT DEPENDENCY OF PHOTODYNAMIC THERAPY

光动力疗法（PDT）的有效性取决于同时 肿瘤组织中存在光敏剂、氧和光。 因素 限制这些参数中的任何一个都将限制PDT。 一个这样的限制 因素可能是缺氧肿瘤细胞区域的存在， 由于肿瘤血液供应不良而在PDT之前存在，或者可能是 由于严重的血管损伤， 由PDT诱导。 另一个可能的限制因素是 出血伴随PDT诱导的血管损伤， 在完全有效的光剂量被输送到 肿瘤细胞。 建议审查以下方面的程度和重要性： 这些限制PDT治疗在体内。 PDT治疗的氧依赖性将在细胞内测定。 在体内卟啉摄取条件下获得的藜芦醇浓度。 预先存在的缺氧肿瘤细胞区域对in的可能影响 将检查体内PDT。 PDT血管损伤对肿瘤的影响 氧合和急性缺氧肿瘤区域的可能产生， 将研究PDT光递送。 将检查是否有肿瘤 PDT后发生再氧合。 光动力治疗过程中皮肤和肿瘤组织的光穿透性变化 将被监测，并将测量由于出血导致的光损失。 携氧增强肿瘤氧合的可能性 化学品和高氧呼吸可能会增强光动力肿瘤 将研究销毁。

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.