Abstrakt: |
In clinical photochemotherapy, irradiation is delayed by a few days with respect to sensitizer injection in order to enhance the specificity of action. However, there are animal experiments which, above all, require a strong response; this is expected to occur if the delay time is much shorter. To assess the influence of the delay time, lesions were produced in rat ears using haematoporphyrin derivative and green light, and characterized by a scoring system. It was found that, starting from the shortest experimentally accessible value (8 min), the intensity of lesions decreases with increasing delay time (by a factor of 2 in 90 min). This result suggests that the lesions are induced by circulating sensitizer. Dose fractionation, performed 97 min after injection, enhances the response ( p<0.005). [ABSTRACT FROM AUTHOR] |