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Protective effect of ascorbic acid in experimental gastric cancer: reduction of oxidative stress

World Journal of Gastroenterology 2003年第3期9卷 446-448页

作者： Claudia P.m.S.Oliveira Paulo Kassab Fabio P.Lopasso Heraldo P.Souza m.riano janiszewski Francisco R.m.Laurindo Kioshi Iriya Antonio A.Laudanna Department of Gastroenterology of medical School of University of So Paulo (USP) So PauloBrazil Department of Emergency medicine of mcdical School of University of So Paulo (USP) So PauloBrazil Heart Institute of medical School of University of So Paulo (USP) So PauloBrazil Depatment of Pathology of medical School of University of So Paulo (USP) So PauloBrazil

AIm: Oxidative stress participates in the cell carcinogenesis by inducing DNA mutations. Our aim was to assess whether ascorbic acid, an antioxidant, could have a role in preventing ROS (Reactive Oxygen Species) generation in experimental gastric carcinoma in a rat ***: Experimental gastric cancer was induced in twelve Wistar male rats (weighting 250-350 g) by profound duodeno-gastric reflux throught split gastrojenunostomy. The rats were allocated to the following groups: Group Ⅰ (n=6)was the control; Group Ⅱ (n=6) which was mantained with daily intake of tape water with Vitamin C (30 mg/Kg). After 6 or 12 months, samples of gastric tumor or non tumor mucosa were taken from the anastomosis of both *** stress was measured by superoxide quantification through lucigenin-amplified chemiluminescence base and by staining with Nitrobluetetrazolium. The histopathologic confirmation of adenocarcinoma was made by eosinhemathoxilin ***: The intestinal type of gastric adenocarcinoma was microscopically identified in all animals of group Ⅰwhereas only 3 rats of group Ⅱ showed an adenocarcinoma without macroscopic evidence of them. The cancers were located in the anastomosis in all cases. Basal luminescence from tumor gastric tissue generated 38.4±6.8 count per minute/mg/x106 (mean±SD) and 14.9±4.0 count per minute/mg/×106, respectively, in group Ⅰ and Ⅱ animals (P＜0.05). The Nitrobluetetrazolium method showed intense staining in tumor tissues but not in non neoplasic ***: Experimental gastric tumors seem to produce more reactive oxygen species than non neoplasic gastric tissue. The reduction of oxidative stress and gastric tumor incidence in rats were induced by the intake of ascorbic acid. Therefore, it may have a role in the prevention of gastric carcinoma.

关键词：维生素C酸胃癌氧化损伤作用机制动物模型

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The Influence of Surge Arrester Location on Over-Voltages Caused by Direct Lightning Strikes to mV Lines

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Journal of Energy and Power Engineering 2014年第3期8卷 508-514页

作者： Alexandre Piantini Thais O. de Carvalho Paulo F. Obase Jorge m. janiszewski Gilnei J. G. Santos Donorvan R. Fagundes Institute of Energy and Environment University of Sao Paulo Sao Paulo 05508-010 Brazil Polytechnic School University ofS6o Paulo S6o Paulo 05508-010 Brazil AES SUL Coordination of Planning and Engineering S6o Leopoldo 93010-060 Brazil

In the period 2003-2011, lightning over-voltages accounted for about 47% of the total number of distribution transformer failures observed in the service area of AES Sul, a power company that operates in the state of Rio Grande doSul, in South Brazil. This paper presents the results of an investigation on the influence of the distance between transformer and mV arresters on the surges at the transformer windings caused by direct strikes to the mV network. The analysis, performed through simulations using the Alternative Transients Program, shows that in general higher voltages are produced by subsequent strokes. Although in relation to the primary side the surges transferred to the secondary are much less affected by the distance between transformers and primary arresters, such distance should always be kept as short as possible in order to reduce the probability of occurrence of transformer failures due to over-voltages at the mV bushings.

关键词：雷电过电压避雷器变压器故障压线位置 Grande 中压电网变压器绕组

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