Subject spin trapping

Despite their short half-lives, it is possible to detect free radicals in biological tissues by the addition of nonradicals such as nitrones or nitroso compounds, which act as spin traps by forming relatively stable free radicals on reaction with the endogenous radical species. Utilizing the technique of electron spin resonance (e.s.r.) spectroscopy, we have demonstrated ROM generation by human rheumatoid synovium when subjected to cycles of hypoxia/normoxia in vitro. Using 3,5-dibromo-4-nitroso-benzenesulphonate (DBNBS) as a spin trap, a... 

Gas-phase spin trapping has been the subject of a short review article (Janzen, 1976). 

As already mentioned in Section 1, the radical ion-mediated mechanism, often to be denoted as inverted spin trapping in the following, was discussed and experimentally supported in several isolated cases in the period between 1975 and 1990, but was not subjected to systematic study. In addition, numerous studies were performed on systems which, in the light of later developments, must have involved inverted spin trapping, but which were interpreted differently. Two particularly interesting cases involve the formation of fluoro and acetoxy spin adducts. 

Any species dissolved in the water is clearly going to be subject to chemical reaction with these ultrasonically produced radicals and/or hydrogen peroxide. Thus if iodide ion is present in solution iodine will be liberated. Spin trapping ESR techniques afforded positive identification of the radical species sonically generated in water [40]. 

The photochemical acceleration of a variety of other reactions involving Al(Por)R is observed, and as a result, the mechanism of this photochemical activation is important and was the subject of two studies. In the first, a spin trap (tributylnitrosobenzene) was added to Al(TPP)Et in the dark, and slow production of Et (trapped as ArN(Et)0 ) was observed by EPR spectroscopy. Upon irradiation the amount of this product increased and a signal corresponding to the Al—O... 

Bahrani et al. have detected NO in the intestines and blood of rats subjected to intestinal IR.371 Other workers have used spin trapping to detect radical... 

Spin trapping can also be used to investigate the different dose-response effects of SOD in rat and rabbit hearts, subjected to ischemia and reperfusion. Does the spin-adduct formation also follow a bell-shaped dose-response relationship observed with SOD Additional studies are clearly needed to explain the protective and deleterious aspects of SOD in ischemia and reperfusion injury. 

Prior to irradiation, some extracted films were immersed in hexane solutions of stabilizers for 15 h. After removal, rinsing and drying the film, the absorbed stabilizer levels were quantified by IR spectroscopy using the 1738 cm-1 ester band in all cases. The stabilizers employed included 1,2,2,6,6-pentamethyl-4-piperidyl octadecanoate (StNCH3), 2,2,6,6-tetramethyl-4-piperidyl-N-oxyl (StNO ), octadecyl e-(3,5-di-tert.-butyl-4-hydroxyphenyl)-propionate (AOX) and d1-octadecyl 3,3 -thiodipropionate (DSTDP). Subsequent to irradiation, some films were subjected to treatment by overnight immersion in a solution of a spin trap (2-methyl-2-nitrosopropane, 0.024 mol L-1 in hexane) or in an atmosphere of a reactive gas (SF4 or S02) to selectively derivitize the polymeric products (8). 

Spin-trapping with Bu NO has been used to identify radicals formed from reaction of hydroxyl radicals with pyrimidine nucleosides. Although the main discussion in this paper conconed radicals in the pyrimidine ring, sugar radicals were also discussed briefly. A study has been presented on the formation of radicals in the ribose units when RNA, frozen in water, was subjected to Co y-irradiati[Pg.271]

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