932 resultados para Damage of flood


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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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There has been little research on geochemistry and isotopic compositions in tholeiites of the Northern region from the Paraná Continental Flood Basalts (PCFB), one of the largest continental provinces of the world. In order to examine the mantle sources involved in the high-Ti (Pitanga and Paranapanema) basalt genesis, we studied Sr, Nd, and Pb isotopic systematics, and major, minor and incompatible trace element abundances. The REE patterns of the investigated samples (Pitanga and Paranapanema magma type) are similar (parallel to) to those of Island Arc Basalts' REE patterns. The high-Ti basalts investigated in this study have initial (133Ma) 87Sr/86Sr ratios of 0.70538-0.70642, 143Nd/144Nd of 0.51233-0.51218, 206Pb/204Pb of 17.74-18.25, 207Pb/204Pb of 15.51-15.57, and 208Pb/204Pb of 38.18-38.45. These isotopic compositions do not display any correlation with Nb/Th, Nb/La or P2O5/K2O ratios, which also reflect that these rocks were not significantly affected by low-pressure crustal contamination. The incompatible trace element ratios and Sr-Nd-Pb isotopic compositions of the PCFB tholeiites are different to those found in Tristan da Cunha ocean island rocks, showing that this plume did not play a substantial role in the PCFB genesis. This interpretation is corroborated by previously published osmium isotopic data (initial γOs values range from+1.0 to+2.0 for high-Ti basalts), which also preclude basalt generation by melting of ancient subcontinental lithospheric mantle. The geochemical composition of the northern PCFB may be explained through the involvement of fluids and/or small volume melts related to metasomatic processes. In this context, we propose that the source of these magmas is a mixture of sublithospheric peridotite veined and/or interlayered with mafic components (e.g., pyroxenites or eclogites). The sublithospheric mantle (dominating the osmium isotopic compositions) was very probably enriched by fluids and/or magmas related to the Neoproterozoic subduction processes. This sublithospheric mantle region may have been frozen and coupled to the base of the Parana basin lithospheric plate above which the Paleozoic subsidence and subsequent Early Cretaceous magmatism occurred. © 2013 Elsevier Ltd.

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Chronic cardiomyopathy is the most important clinical form of Chagas disease, and it is characterised by myocarditis that is associated with fibrosis and organ dysfunction. Alternative treatment options are important tools to modulate host immune responses. The main goal of this work was to evaluate the anti-inflammatory actions of melatonin during the chronic phase of Chagas disease. TNF-α, IL-10 and nitrite concentrations were evaluated as predictive factors of immune modulation. Creatine phosphokinase-MB (CK-MB), cardiac inflammatory foci and heart weight were assessed to evaluate the efficacy of the melatonin treatment. Male Wistar rats were infected with 1 × 105 blood trypomastigotes of the Y strain of Trypanosoma cruzi and kept untreated for 60 days to mimic chronic infection. After this period, the rats were orally treated with melatonin 50 mg/kg/day, and the experiments were performed 90, 120, and 180 days post-infection. Melatonin treatment significantly increased the concentration of IL-10 and reduced the concentrations of NO and TNF-α produced by cardiomyocytes. Furthermore, it led to decreased heart weight, serum CK-MB levels and inflammatory foci when compared to the untreated and infected control groups. We conclude that melatonin therapy is effective at protecting animals against the harmful cardiac inflammatory response that is characteristic of chronic T. cruzi infection. © 2013 Elsevier B.V. All rights reserved.