He et al. (pp.585-591) used Immuno-Spin Trapping, where the spin-trapping technique was combined with ELISA and Western blotting methods to study the formation of metHb radicals. The application of this new methodology led to the detection of low concentrations of protein derived radicals. The radicals are first spin trapped with DMPO, followed by the formation of an auto-oxidation product. It is this product that is detected through antigen-antibody interactions. The effect of UVA irradiation and the presence of ketoprofen in isolation and combined was studied. The formation of radicals was enhanced when ketoprofen was used as a sensitizer for the reaction with purified hemoglobin as well as in the presence of red blood cells. The formation of the radicals is dependent on the UVA dose and the ketoprofen concentrations, and resulted mainly from the formation of H^sub 2^O^sub 2^. This work provides new insights into the potential mechanisms for the phototoxicity and photo-allergy of ketoprofen when used as a non-steroidal anti-inflammatory drug. In addition, the development of Immuno-Spin Trapping will be applicable to many other circumstances in photobiology when reactions leading to low concentrations of radicals occur.
Cornelia Bohne
Dye Induces DNA-histone Protein Cross-linking Under Normal Exposure Conditions
In a Rapid Communication in this issue (pp. 675-679), Davis and Bardeen examine the effect of 365 and 410 nm illumination on the dye Hoechst 33342 induced protein-DNA cross-linking. The authors conclude that normal exposure conditions, in particular in fluorescence microscopy, can have consequences in live cell experiments or cell sorting procedures. While not directly affecting DNA, exposure creates chemical changes in the chromatin which contain the DNA in living cells. The effects are particularly relevant in long exposure experiments, such as microscopy, but may be significantly smaller for short exposures, such as those required in flow cytometry.
J. C. Scaiano
Copyright American Society of Photobiology Jun 2003
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