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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-22 2:10 |
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Conference: Bucharest University Faculty of Physics 2012 Meeting
Section: Biophysics; Medical Physics
Title:
Interaction of ultraviolet radiations with living matter. Medical applications
Authors:
Doina GAZDARU, Claudia CHILOM, A. POPESCU
Affiliation:
Dept. Electricity, Solid State and Biophysics, Faculty of Physics, University of Bucharest, Romania
E-mail
aurel.popescu.46@gmail.com
Keywords:
Interactions, living matter, nucleic acids, phototherapeutic effect, UV radiations
Abstract:
Living matter had appeared, had evolved and is currently operating under an inevitable and permanent interaction with all kinds of radiations: corpuscular and electromag-netic, non-ionising and ionising ones. Some of these interactions are beneficent for biosystems, while others induce biomolecular lesions (i.e., protein and/or nucleic acid breakings) with negative consequences at higher level of living matter organization (e.g., at cellular, tissular, and organism levels). We shall focus only to one class of electromagnetic radiations, namely, those pertaining to ultraviolet (UV) domain. While long wavelength UV radiations are able to induce only molecular excitations, the short wavelength UV radiations are able to provoke breakings of chemical bonds and ionisations of the component atoms of proteins and nucleic acids. Fortunately, the living matter had succeeded to counterbalance the harmful effect of these radiations, developing very useful defence enzymatic systems. For instance, the single strand break of DNA is actively repaired by a set of cooperating enzymes, plastically called “cut and patch system”. This system, present in each skin cell, is assuring the repair of the lesions induced in DNA strands by UV radiations, during the sun exposure of the body. In exchange, the long wavelength UV radiations are stimulating cellular melanin synthesis with a protective effect against the harmful short wavelength radiations.The interaction mechanism between UV radiations and living matter is very intricate. Therefore its deciphering is absolutely necessary in order to prevent the undesired cellular effects of UV radiations, or to use these radiations in therapeutic purposes. For instance, combining the effect of UV radiations with a prior specific drug administration (i.e., exploiting the UV photodynamic effect), one can apply an efficient phototherapy in curing some diseases (e.g., psoriasis).
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