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Photodynamic Treatment with Fractionated Light Decreases Production of Reactive Oxygen Species and Cytotoxicity In Vitro via Regeneration of Glutathione

Authors

  • Cristian Benno Oberdanner,

    1. Division of Allergology and Immunology, Department of Molecular Biology, University of Salzburg Hellbrunnerstrasse 34, 5020 Salzburg, Austria
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  • Kristjan Plaetzer,

    1. Division of Allergology and Immunology, Department of Molecular Biology, University of Salzburg Hellbrunnerstrasse 34, 5020 Salzburg, Austria
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  • Tobias Kiesslich,

    1. Division of Allergology and Immunology, Department of Molecular Biology, University of Salzburg Hellbrunnerstrasse 34, 5020 Salzburg, Austria
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  • Barbara Krammer

    Corresponding author
    1. Division of Allergology and Immunology, Department of Molecular Biology, University of Salzburg Hellbrunnerstrasse 34, 5020 Salzburg, Austria
      *To whom correspondence should be addressed: Division of Allerology and lmmunology, Department of Molecular Biology, University of Salzburg, Hellbrunnerstrasse 34, 5020 Salzburg, Austria. Fax: ++43-662-8044-150; e-mail: barbara.krammer@sbg.ac.at.
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  • Posted on website on 1 February 2005

*To whom correspondence should be addressed: Division of Allerology and lmmunology, Department of Molecular Biology, University of Salzburg, Hellbrunnerstrasse 34, 5020 Salzburg, Austria. Fax: ++43-662-8044-150; e-mail: barbara.krammer@sbg.ac.at.

ABSTRACT

Photodynamic therapy removes unwated or harmful cells by overproduction of reactive oxygen species (ROS). Fractionated light delivery in photodynamic therapy may enhance the photodynamic effect in tumor areas with insufficient blood supply by enabling the reoxygenation of the treated area. This study addresses the outcome of fractionated irradiation in an in vitro photodynamic treatment (PDT) system, where deoxygenation can be neglected. Our results show that fractionated irradiation with light/dark intervals of 45/60 s decrease ROS production and cytotoxicity of PDT. This effect can be reversed by addition of 1,3-bis-(2-chlorethyl)-1-nitrosurea (BCNU), an inhibitor of the glutathione allow the glutathione reductase to regenerate reduced glutathione (GSH), thereby rendering cells less susceptible to ROS produced by PDT compared with continnous irradiation. Our results could be of particular clinical importance for photodynamic therapy applied to well-oxygenated tumors.

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