Different Susceptibility of Cells of Porcine Skin and Internal Organs to Ultraviolet A-Induced Breaking of Nuclear DNA

Authors

  • Anna Brożyna,

    1. Department of Medical Biology, Institute of General and Molecular Biology, Nicolaus Copernicus University, Torun, Poland
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  • Barbara W. Chwirot

    Corresponding author
    1. Department of Medical Biology, Institute of General and Molecular Biology, Nicolaus Copernicus University, Torun, Poland
      *To whom correspondence should be addressed: Department of Medical Biology, Institute of General and Molecular Biology, Nicolaus Copernicus University, ul. Gagarina 9, 87-100 Torun, Poland. Fax: 4856-6114-785; e-mail: chwirot@biol.uni.torun.pl
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  • Posted on the website on 14 March 2005

*To whom correspondence should be addressed: Department of Medical Biology, Institute of General and Molecular Biology, Nicolaus Copernicus University, ul. Gagarina 9, 87-100 Torun, Poland. Fax: 4856-6114-785; e-mail: chwirot@biol.uni.torun.pl

ABSTRACT

There is a continuously growing interest in medical applications of ultraviolet radiation (UV-A and long-wavelength UV-B) especially for laser surgery, phototherapy and photodiagnostics of human internal organs. UV-B and UV-A radiation is potentially mutagenic, however, there has been very little information published to date concerning the significance of possible deleterious action of such photons on cells of internal tissues. The aim of this study is to compare the sensitivities of skin cells to those of internal organs upon exposure to UV-A. To assess this sensitivity we have determined the UV-A dose-dependent frequency of nuclear DNA breaks detected with the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end-labeling (TUNEL) technique. The materials for the study were macroscopic samples of porcine skin, colon and esophagus. The UV-A dose ranged from 0.1 to 1000 mJ/cm2, which is similar to doses received by cells in regions examined with laser-induced fluorescence or by cells surrounding areas subject to a laser ablation. To reduce the influence of DNA repair processes the tissue samples were kept at a low temperature during the irradiation and were deep frozen immediately after completing the irradiation procedure. The cells of the internal organs are much more susceptible to UV-A-induced breaking of DNA than the skin cells. The percentage fractions and the spatial distributions of the damaged cells and the characteristics of the UV-A dose dependence seem to vary by type of internal organ.

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