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Journal of Environmental Pathology, Toxicology and Oncology
Facteur d'impact: 1.625 Facteur d'impact sur 5 ans: 1.63 SJR: 0.402 SNIP: 0.613 CiteScore™: 2.3

ISSN Imprimer: 0731-8898
ISSN En ligne: 2162-6537

Journal of Environmental Pathology, Toxicology and Oncology

DOI: 10.1615/JEnvironPatholToxicolOncol.v30.i3.60
pages 235-240

Fluorescence Photobleaching of ALA and ALA-Heptyl Ester Induced Protoporphyrin IX During Photodynamic Therapy of Normal Hairless Mouse Skin: A Comparison of Two Light Sources and Different Illumination Schemes

Xiao Pudroma
Department of Physics, Tibet University, Lhasa, China
Asta Juzeniene
Department of Radiation Biology, Institute for Cancer Research, Norwegian Radium Hospital, Oslo University Hospital, Montebello, 0310 Oslo, Norway
Li-Wei Ma
Department of Radiation Biophysics, Institute for Cancer Research, Rikshospital-Radiumhospital HF and Plasma/Room Physics, University of Oslo, Oslo, Norway
Vladimir Iani
Department of Radiation Biophysics, Institute for Cancer Research, Rikshospital-Radiumhospital HF and Plasma/Room Physics, University of Oslo, Oslo, Norway
Johan Moan
Department of Radiation Biophysics, Institute for Cancer Research, Rikshospital-Radiumhospital HF and Plasma/Room Physics, University of Oslo; lnstitute of Physics, University of Oslo, Blindern, Oslo, Norway

RÉSUMÉ

This study investigated photobleaching of protoporphyrin IX (PpIX) induced by 5-aminolevulinic acid (ALA) and ALA-heptyl ester during superficial photodynamic therapy (PDT) in normal skin of the female BALB/c-nu/nu athymic mouse. We examined the effects of two light sources (laser and broadband lamp) and two different illumination schemes (fractionated light and continuous irradiation) on the kinetics of photobleaching. Our results show that light exposure (0−30 minutes, 10 mW/cm2) of wavelengths of approximately 420 nm (blue light) and 635 nm (red light) induced time-dependent PpIX photobleaching for mouse skin of 2% ALA and ALA-heptyl ester. Blue light (10 mW/cm2) caused more rapid PpIX photobleaching than did red light (100 mW/cm2), which is attributed to stronger absorption at 407 nm than at 632 nm for PpIX. In the case of light fractionation, fractionated light induced faster photobleaching compared with continuous light exposure after topical application of 2% ALA and ALA-heptyl ester in vivo. These have been suggested to allow reoxygenation of the irradiated tissue, with a consequent enhancement of singlet oxygen production in the second and subsequent fractions.


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