3 February 1999 Quantitative methods for studying the role of free radicals in biology
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The mechanism of the primary sensitization steps in Photodynamic Therapy could be of essential importance concerning the efficiency of the treatment. Besides the well known mechanisms there is a possibility that the interaction between the excited triplet state sensitizer and the doublet state free radicals generated by the cells adds a significant contribution to the overall photodynamic effect. To support this hypothesis the quantification and identification of free radicals would be required. For this purpose chemiluminescence studies and spin trapping seemed to be the most suitable methods due to the extremely short lifetime of free radicals in biological systems. We present data on the kinetics of accumulation of free radicals: (1) by measuring luminol- dependent chemiluminescence of stimulated macrophages both in the absence and in the presence of a free radical inhibitor 3,5 di-tert-butyl-4-hydroxyphenyl propionic acid; (2) by following the production of primary, secondary and tertiary radical adducts using DMPO (5,5-dimethyl-1-pyrroline N-oxide) as spin trapping agent in chemical model systems. The measured data are used to determine the effect of the excited sensitizers on the kinetics of accumulation of free radicals under biological conditions. These results would serve to design new and more effective sensitizers used for therapy based on the triplet-doublet mechanism of action.
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Judit Jakus, Judit Jakus, Tamas Kriska, Tamas Kriska, Tatjana K. Maximova, Tatjana K. Maximova, Andras Nemeth, Andras Nemeth, Laszlo Korecz, Laszlo Korecz, Dezso Gal, Dezso Gal, } "Quantitative methods for studying the role of free radicals in biology", Proc. SPIE 3563, Photochemotherapy of Cancer and Other Diseases, (3 February 1999); doi: 10.1117/12.339125; https://doi.org/10.1117/12.339125

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