Preface: special issue of photodynamic therapy and photodetection with porphyrin precursors for the journal of environmental pathology, toxicology, and oncology.

摘要

The collection of articles put together in this special issue originated from a selection of papers presented at the 5th International Workshop on Photodynamic Therapy and Photodetection with Porphyrin Precursors, held in Buenos Aires, Argentine, June 22-24, 2006. This meeting was attended by leading scientists from 13 countries of the world, whom we have had the pleasure and honor of having been closely associated with or known for a long time. The four previous International Workshops on Photodynamic Therapy with Aminolevulinic Acid had been organized by Professor Stanley Brown, at Leeds in the United Kingdom, in the periods of April 29-31,1995; April 24-26,1998; April 14-16, 2000; and April 19-21, 2002. Porphyrin synthesis is one of the most fundamental attributes of all living cells. Porphyrins are considered "the pigments of life" as coined by Lemberg and Ledge in 1944. Porphyrins are the only photosensitizers synthesized in the cells, and the best examples of these endogenous sensitizers are the porphyrin intermediates formed and accumulated in the cutaneous porphyrias, producing the characteristic skin photosensitization. Photodynamic therapy (PDT) is a promising new modality of cancer treatment, which involves the combination of a photosensitizing agent that is taken up selectively and retained by tumoral cells, and light of an appropriate wavelength. Separately, each of these factors is harmless by itself, although when combined in the presence of oxygen, cytotoxic reactive oxygen species are produced, leading to irreversible cellular damage and causing cell death and tumor destruction. After either exogeneous administration or endogenous synthesis, porphyrins finally accumulate in higher proliferative cells.