34 resultados para Acide de Lewis


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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Pós-graduação em Biociências e Biotecnologia Aplicadas à Farmácia - FCFAR

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Pós-graduação em Educação para a Ciência - FC

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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

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Espécies do gênero Strongyloides são importantes parasitas de humanos e animais domésticos e aquelas que parasitam roedores são freqüentemente utilizadas como modelos experimentais para o estudo da estrongiloidíase. S. venezuelensis parasita ratos (Rattus norvegicus) e seu estudo tem permitido o entendimento de mecanismos imunológicos envolvidos na relação parasita–hospedeiro da estrongiloidíase humana e animal. O diagnóstico parasitológico de S. venezuelensis pode ser realizado pela detecção de ovos embrionados nas fezes, com o uso do OPG (ovos por grama de fezes), também empregado no monitoramento da infecção. Entretanto, essa técnica se mostra pouco sensível quando a carga parasitária é leve. Os métodos moleculares aumentam a sensibilidade e a especificidade das análises. A PCR tem se mostrado como uma técnica sensível e precisa na detecção de parasitas em tecidos e fezes de hospedeiros infectados. A fim de comparar a sensibilidade das técnicas de OPG e PCR em ratos Lewis infectados por S. venezuelensis, foram realizados dois protocolos no presente estudo. No Protocolo I foi comparada a sensibilidade das duas técnicas em amostras de ratos Lewis com diferentes cargas parasitárias. A PCR com o emprego par de primers descrito por Dorris et al. (2002) obteve melhores resultados que o OPG nos grupos inoculados com 40 L3, considerada como infecção leve. Entretanto, não foi verificada diferença estatística significativa entre as técnicas (P>0,05), provavelmente por terem sido utilizados poucos animais (n=10). O outro par de primers utilizado foi desenhado a partir de uma seqüência parcial do gene do rDNA de S. venezuelensis e não foi capaz de detectar a presença do DNA do helminto em nenhuma amostra desse grupo. Já nos grupos inoculados com 400 e 4000 L3, tanto a PCR com...(Resumo completo, clicar acesso eletrônico abaixo)

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The use of pesticides in Brazil has intensified over the years. And since 2009 it was ranked as the largest market for pesticides worldwide. The consequential diffuse contamination of the environment is therefore due to the increasing number of chemicals of different classes, origins and modes of action. Little is known about the action of pesticides on human health in situations of co-exposure. Possible toxic effects are not restricted to agricultural and industrial workers, but also the general population that may be exposed continuously to its residues in food and water. Although these pesticides are mostly present in the environment at low doses, it must be considered that possible cumulative or synergistic effects may occur when there are concurrent or sustained exposure for two or more of these agents, which can lead to late manifestation of subclinical damages, sometimes irreversible. Thus, the specific objective of this study was to assess the effect of carcinogenesis promotion of a mixture of pesticides at low doses and analyze the phenomena of cell proliferation and apoptosis in rat liver. A total of 50 male Lewis rats was separated into 5 groups for 8 weeks in a medium term hepatocarcinogenesis model. The three different classes of pesticides (dieldrin, dicofol, endosulfan, dichlorvos and permethrin), whose residues were detected by ANVISA during the period from 2001 to 2005 in tomatoes cultures, were added to the feed of rats initiated to hepatocarcinogenesis with diethylnitrosamine (DEN- 200mg/kg ip). We used two different mixtures, one with no toxic effects at doses (MEX1) referring to the NOEL (no-observed-effect level) and another at doses LOEL / LEL / LOAEL (Lowest-observed-effect level / Lowest-effect level / Lowest -observed-adverse-effect level), to the installation of adverse effects (MEX2), derived from chronic studies. All animals ...(Complete abstract click electronic access below)

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The NbCl5 being a strong electrophile, is a potential candidate to act as a Lewis acid, and therefore it mediates various organic reactions. For this reason, it has received continuous attention by Brazilian researchers, especially in recent decades, since Brazil holds the largest reserves of niobium, besides being the largest producer of this element. The Michael addition reaction is one of the most widely used for forming carbon-carbon bonds and takes place by the addition of nucleophiles to activated olefins. Although this type of reaction is usually catalyzed by base, there are reports in the literature on the use of various Lewis acids in this type of reaction. The synthesis of enamines based acetilenodicarboxilates and amines, aromatic or alkyl, by Michael addition reaction is quite interesting, since these are valuable synthetic intermediates for the synthesis of heterocyclic and they are used in multicomponent reactions. The derivatives of anilino-fumarate also have a great potential for medical application. In this study we investigated the use of niobium pentachloride as Lewis acid to catalyze the Michael additions between the derivatives of aniline and acetilenodicarboxilates the synthesis of enamines

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Pós-graduação em Cirurgia Veterinária - FCAV

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Research partly motivated by Lewis Carroll's Euclid and his modern rivals (1879) portuguese translation, this paper presents some hermeneutical remarks taken as necessary to understand the context in which such book was produced. The paper focuses particularly on education, in general, and on the teaching of mathematics and Geometry in victorian England.

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The Brazilian federal government Agency for Health Surveillance detected pesticide residues in fresh food available for consumers all over the country. The current study investigated the effects of a mixture of some of those pesticides (dichlorvos, dicofol, dieldrin, endosulfan, and permethrin) on the reproductive system of Sprague-Dawley (SD), Wistar (WT), and Lewis (LEW) rats. Female rats from each strain were randomized into three experimental groups and were fed a control diet or diets added with pesticides mixture at their respective no-observed-effect level (NOEL)/no-observed-adverse-effect level (NOAEL) (low dose) (mg/kg/d): dichlorvos (0.23), dicofol (0.5), dieldrin (0.025), endosulfan (0.7), permethrin (5), or lowest-observed-effect level (LOEL)/lowest-effect level (LEL)/ lowest-observed-adverse-effect level (LOAEL) (toxically effective dose) (mg/kg/d): dichlorvos (2.3), dicofol (2.1), dieldrin (0.05), endosulfan (3.8), and permethrin (25) as reported in the literature. Euthanasia was performed between wk 10 and 12, during the estrous stage. Decreased body weights gain (SD and WT) and increased liver weights (SD, WT, and LEW) were observed in each strain fed the pesticides mixture at the higher levels. At that dose level, rat strains also varied in their responses regarding the estrous cycle, hormonal levels, and number of developing ovarian follicles. The studied mixture of pesticides was found to interfere with the female reproductive system when individual pesticides were mixed above a certain level, indicating a threshold exists for each of the strains studied.

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