917 resultados para CASCADE REACTION


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

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Two groups of mice were infested with first stage larvae of the human bot-fly, Dermatobia hominis (Linnaeus Jr) (Diptera: Oestridae). In the first group, skin biopsies were carried out 1, 3, 5, 7, 10 and 18 days after infestation. The second group was also infested but had all the larvae removed 5 days after infestation. The mice in the latter group were reinfested 4 weeks later and skin biopsies were carried out 1, 3, 5, 7, 10 and 18 days after reinfestation. In the first group, an inflammatory reaction began slowly, the neutrophils being the main inflammatory cells, eosinophils being scarce. The reaction progressed with time, developing a necrotic halo around the larvae containing inflammatory cells surrounded by fibroblasts. The inflammation invaded the adjacent tissue. In the second group, the inflammatory reaction was intense on the day immediately after reinfestation, the pattern being changed by the presence of a large number of eosinophils. Activated fibroblasts surrounding the necrotic area around the larvae appeared 3 days after reinfestation in the second group and 7 days after infestation in the first group. The results demonstrated that the previous contact with the antigens elicited the early arrival of eosinophils, probably through the chemotactic factors liberated by mast cells in the anaphylactic reaction.

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Hepatozoon canis was molecularly identified in Rio de Janeiro State, Brazil. Twelve dogs from urban areas were studied by blood smear examination and the polymerase chain reaction (PCR) assay. From these dogs, only 1 was positive in both blood smears and PCR.

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Total phosphorus concentrations in the sediment of a cascade of 8 reservoirs located in the Paranapanema River (SE, Brazil) were analysed during two consecutive seasonal periods (2000 and 200 1). The reservoirs of Jurumirim, Chavantes, Salto Grande, Canoas 11, Canoas 1, Capivara, Taquarucu and Rosana were built during the last five decades with the purpose of hydroelectric generation. The sampling points were distributed along a 700 km of river stretch in 19 stations distributed in the river-reservoirs zones and main tributaries as well as in 5 stations representing the adjacent wetlands. The nutrient concentration was determined in samples from surface layers of sediment. Temporal and spatial changes were observed for both years. Three different areas could be identified along the river, considering not only Tot-P variations but also others physical and chemical characteristics such as organic matter concentration, nitrogen concentration of sediment and 02, pH, conductivity and Eh measured in the bottom layer of the water column. Higher values of Tot-P were found in the middle and lower region of the Paranapanema basin (maximum value of 1.96 mg g(-1) in Tibagi River in October/2001). Agricultural practices and cattle raising are the main external sources of nutrient in these regions. Superficial or sub-superficial watershed drainage and tributaries entrances are important nutrient contributors, leading to an increasing accumulation of nutrient in the sediment. This process seems to be especially important in the middle region of the Paranapanema Valley, were the values of Tot-P were higher comparing to the other areas.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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We investigated the presence of mast cell granules in macrophages following an in vivo model of an allergic reaction. Injection of ovalbumin (100 mug) into the peritoneal cavity of sensitised mice produced a rapid (within 2 h) influx of neutrophils followed by a slower (after >4 h) eosinophil migration. Ovalbumin treatment induced a high incidence (similar to 50%) of mast cell degranulation compared to control phosphated-buffered saline-treated mice. The majority (similar to 90%) of peritoneal macrophages contained mast cell granules as early as 2 It post-ovalbumin, with lower values at later time-points, as determined by staining with Toluidine blue and Berberine sulphate. This was confirmed by electron microscopy which enabled us to identify the complex mast cell granule sub-structural components in macrophage phagosomes. In conclusion, we used histochemical and ultrastructural analyses to show that mast cell granules become internalised with macrophages during the early stages of an experimental allergic reaction. (C) 2001 Academic Press.

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omeprazole is a substituted benzimidazole which suppresses gastric-acid secretion by means of H+, K+-ATPase inhibition. It is an optically active drug with the sulfur of the sulfoxide being the chiral center. This pro-drug can be easily converted into its respective sulfenamide at low pH. In this work, omeprazole has been studied in relation to racemization barrier and decomposition reaction. Quantum chemistry coupled to PCA chemometric method were used to find all minimum energy structures. Conformational analysis and calculation of racemization barriers were carried out by PM3 semiempirical method (Gaussian 98). The average racemization energy barrier for all minimum energy structures (43.56 kcal mol(-1)) can be related to the velocity constant in Eyring's equation. The enormous half-life time at 100 degrees C (9.04 x 10(4) years) indicates that the process cannot be observed in human time scale. on the other hand, the difference of free energy change (Delta(Delta G) = -266.78 kcal mol(-1)) for the decomposition reaction shows that the process is favorable to the sulfenamide formation. The highly negative Delta(Delta G) obtained for the decomposition reaction shows that this process is extremely exothermic. This result explains why omeprazole decomposes and does not racemize. (C) 2008 Wiley Periodicals, Inc.

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Homogeneous catalysts prepared from rhodium trichloride in aqueous aromatic amines have been shown to reduce C-CI bonds under mild water gas shift conditions (T=100 degrees C, P-CO = 1.0 atm). In a 4-picoline/water solvent mixture, 1,2-dichloroethane is reduced to ethylene and ethane in yields compatible with the consumption of the reducing agent CO and with the formation of CO2. Variation of the catalyst solutions by using different substituted pyridines shows a pattern of catalytic activity parallel to that reported previously for H-2 production from the shift reaction, There is a moderate dependence of activity on the basicity of the aromatic amine, but a methyl group at the alpha-position exercises a strong negative steric effect. Long term studies show decrease of the activity with the time perhaps due to the build up of chloride in the medium. (C) 1999 Elsevier B.V. B.V. All rights reserved.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)