84 resultados para Enzymes des sols


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Society for French Studies conference
Liverpool, July 2008

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In spite of the fact that the laterite masonry was often used for building, during the colonial period, the laterite rock is rarely studied. To resolve the economic and environmental problems, concerning the concrete or cinder block construction in Africa, this material can be again a local resource. The objective is to determine the hydro-thermo-mechanical properties of laterite rocks linking with the local geological conditions, to investigate the possibilities to be used in construction housing, sufficiently able to resist to limited loads and to give thermal comfort inside. Some preliminary results are presented here.

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Objective: Enhanced oxidative stress is involved in mediating the endothelial dysfunction associated with hypertension. The aim of this study was to investigate the relative contributions of pro-oxidant and anti-oxidant enzymes to the pathogenesis of endothelial dysfunction in genetic hypertension. Methods: Dilator responses to endothelium-dependent and endothelium-independent agents such as acetylcholine (ACh) and sodium nitroprusside were measured in the thoracic aortas of 28-week-old spontaneously hypertensive rats (SHR) and their matched normotensive counterparts, Wistar Kyoto rats (WKY). The activity and expression (mRNA and protein levels) of endothelial nitric oxide synthase (eNOS), p22-phox, a membrane-bound component of NAD(P)H oxidase, and antioxidant enzymes, namely, superoxide dismutases (CuZn- and Mn-SOD), catalase and glutathione peroxidase (GPx), were also investigated in aortic rings. Results: Relaxant responses to ACh were attenuated in phenylephrine-precontracted SHR aortic rings, despite a 2-fold increase in eNOS expression and activity. Although the activity and/or expression of SODs, NAD(P)H oxidase (p22-phox) and GPx were elevated in SHR aorta, catalase activity and expression remained unchanged compared to WKY. Pretreatment of SHR aortic rings with the inhibitor of xanthine oxidase, allopurinol, and the inhibitor of cyclooxygenase, indomethacin, significantly potentiated ACh-induced relaxation. Pretreatment of SHR rings with catalase and Tiron, a superoxide anion (O) scavenger, increased the relaxant responses to the levels observed in WKY rings whereas pyrogallol, a O -generator, abolished relaxant responses to ACh. Conclusion: These data demonstrate that dysregulation of several enzymes, resulting in oxidative stress, contributes to the pathogenesis of endothelial dysfunction in SHR and indicate that the antioxidant enzyme catalase is of particular importance in the reversal of this defect. © 2003 European Society of Cardiology. Published by Elsevier B.V. All rights reserved.

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After the outbreak of war in 1914 and the subsequent blockade implemented by British navy, the German economy faced serious food shortages leading to famine-like conditions, especially towards the end of the war. As a response to these shortages, the German authorities introduced and implemented socialist policies such as price ceilings and food rations. This study focuses on the inefficient use of high-quality foodstuffs by members of lower social strata by discussing consumer decisions during the First World War from a microeconomic perspective. The German rationing system provided small, but valuable – measured by black market prices – quantities of superior foodstuffs. Especially meat could have been traded on flourishing black markets for greater quantities of inferior staple foods such as bread and potatoes. In this paper I argue that a more efficient use of rations by the poor could have improved their nutritional situation.