The aim of the work was to measure DNA damage induced within tumoral human monocytes by gamma rays, UVA radiation, and exogenous photosensitizers. The accurate HPLC-EC assay was used to determine the level of 8-oxodGuo. The formation of FapyGua and FapyAde was monitored by HPLC/GC-MS analyses after formic acid hydrolysis at room temperature. For this purpose, cells were exposed to relatively high doses of gamma rays and UVA radiation. The extent of formation of FapyGua in the DNA of cells exposed to gamma rays was estimated to be more than 2-fold higher than that of 8-oxodGuo, i.e., about 0. 027 lesion per 10(6) bases per Gy. The yield of FapyAde was estimated to be 1 order of magnitude lower. The latter results were used to calibrate the alkaline comet assay associated with DNA N-glycosylases. The latter approach allowed the determination of the background level (0.11-0.16 Fpg-sensitive site/10(6) bases) and the yields of strand breaks and DNA base damage upon low irradiation doses. Insights into the mechanism of radiation-induced DNA damage were gained from these measurements. A major involvement of (1)O(2) with respect to hydroxyl radicals and type I photosensitization was thus observed within cells exposed to UVA radiation.
Recently there has been growing interest in the effects of antioxidants on insulin activity. In the present study, we investigated the effect of metformin on free radical activity and insulin sensitivity in high fructose-fed rats, a diet that leads to insulin resistance. The animals were divided into four groups (n = 16 per group; experiment duration = 6 weeks): the control (C) group received a standard diet; the control metformin (CM) group was fed a control diet and received metformin (200 mg x kg(-1) x day(-1) in water); the fructose control (FT) group was fed a diet in which fructose composed 56.8% of the total carbohydrates; and the fructose metformin (FM) group received high-fructose diet and metformin (200 mg x kg(-1) x day(-1) in water). The glucose clamp technique was used to determine insulin sensitivity in eight animals per group. Metabolic and oxidative stress parameters were measured in the remaining rats. In the FT rats, insulin resistance, lower red cell CuZn superoxide dismutase activity and lower blood reduced glutathione were observed. Metformin treatment improved both the insulin activity and the antioxidant defense system. In the CM group, metformin had no effect on metabolic parameters, but improved red cell antioxidant enzyme activities and the blood GSH level, which suggests that it has an antioxidant activity independent of its effect on insulin activity.
Topical use of APCs might be helpful in bone reconstruction. No clinical, radiologic, or histologic osteogenesis inhibition of high PLT concentration was observed. The resulting osteogenesis was adapted to dental implant placements.
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