Intensificação da terapia fotodinamica do cancer pela variação da pressão parcial do oxigenio no tecido : efeitos fisicos e biologicos

AUTOR(ES)
DATA DE PUBLICAÇÃO

1997

RESUMO

Photodynamic therapy is based on simultaneous involvement of three factors, namely: tumor tissue retention of an specific photosensitizer; local illumination of the lesion and occurrence of oxygen in the triplet state. Theoretically, changes in any one of these factors may be compensated by a change in the other factors, leading to the same therapeutic resulto Practically this is not true, but we expect to find an ideal combination of these three factors which may give the best clinical results. We present experimental results of PDT under Hyperbaric hyperoxia (HBO) in tumor masses at the dorsal subcutaneous tissue of rats. These tumors were created by previous inoculation of "Walker 256" neoplastic cells. Haematoporphyrin Esther (HpE) was administered as the photosensitizer. The rats were pressurized up to 3 atm, with 100% oxygen continuous ventilation condition in an specially designed hyperbaric chamber. In animaIs treated with PDT/HBO the histology revealed a very important reduction in the number of the tumor cells as compared with PDT controls in normal atmospheric condition, showing numerous apoptotic as well as necrotic cells at the border of the irradiated area. The observed enhancement in the PDT for this situation is, of course, related to extra oxygen in the circulatory system

ASSUNTO(S)

oxigenação hiperbarica fotossensibilização biologica cancer

ACESSO AO ARTIGO

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