978 resultados para Système de sécrétion de type III
Resumo:
Synthesis, structural characterization, and magnetic properties of a new cyano-bridged one-dimensional iron (III)-gadolinium (III) compound, trans-[Gd(o-phen)(2)(H2O)(2)(mu-CN)(2)Fe(CN)(4)], - 2no-phen (o-phen = 1,10-phenanthroline), have been described. The compound crystallizes in the triclinic P (1) over bar space group with the following unit cell parameters: a = 10.538(14) angstrom, b = 12.004(14) angstrom, c = 20.61(2) angstrom, alpha = 92.41(1)degrees, beta = 92.76(1)degrees, gamma = 11 2.72(1)degrees, and Z = 2. In this complex, each gadolinium (III) is coordinated to two nitrile nitrogens of the CN groups coming from two different ferricyanides, the mutually trans cyanides of each of which links another different Gd-III to create -NC-Fe(CN)(4)-CN-Gd-NC- type 1-D chain structure. The one-dimensional chains are self-assembled in two-dimensions via weak C-H center dot center dot center dot N hydrogen bonds. Both the variable-temperature (2-300 K, 0.01 T and 0.8 T) and variable-field (0-50 000 Gauss, 2 K) magnetic measurements reveal the existence of very weak interaction in this molecule. The temperature dependence of the susceptibilities has been analyzed using a model for a chain of alternating classic (7/2) and quantum (1/2) spins. (c) 2005 Elsevier B.V. All rights reserved.
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Using the 1: 2 condensate of benzildihydrazone and 2-acetylpyridine as a tetradentate N donor ligand L, LaL(NO3)(3) (1) and EuL(NO3)(3) (2), which are pale yellow in colour, are synthesized. While single crystals of 1 could not be obtained, 2 crystallises as a monodichloromethane solvate, 2 center dot CH2Cl2 in the space group Cc with a = 11.7099(5) angstrom, b = 16.4872(5) angstrom, c = 17.9224(6) angstrom and beta = 104.048(4)degrees. From the X-ray crystal structure, 2 is found to be a rare example of monohelical complex of Eu(III). Complex 1 is diamagnetic. The magnetic moment of 2 at room temperature is 3.32 BM. Comparing the FT-IR spectra of 1 and 2, it is concluded that 1 also is a mononuclear single helix. H-1 NMR reveals that both 1 and 2 are mixtures of two diastereomers. In the case of the La(III) complex (1), the diastereomeric excess is only 10% but in the Eu(III) complex 2 it is 80%. The occurrence of diastereomerism is explained by the chiralities of the helical motif and the type of pentakis chelates present in 1 and 2.
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Conditions of stress, such as myocardial infarction, stimulate up-regulation of heme oxygenase (HO-1) to provide cardioprotection. Here, we show that CO, a product of heme catabolism by HO-1, directly inhibits native rat cardiomyocyte L-type Ca2+ currents and the recombinant alpha1C subunit of the human cardiac L-type Ca2+ channel. CO (applied via a recognized CO donor molecule or as the dissolved gas) caused reversible, voltage-independent channel inhibition, which was dependent on the presence of a spliced insert in the cytoplasmic C-terminal region of the channel. Sequential molecular dissection and point mutagenesis identified three key cysteine residues within the proximal 31 amino acids of the splice insert required for CO sensitivity. CO-mediated inhibition was independent of nitric oxide and protein kinase G but was prevented by antioxidants and the reducing agent, dithiothreitol. Inhibition of NADPH oxidase and xanthine oxidase did not affect the inhibitory actions of CO. Instead, inhibitors of complex III (but not complex I) of the mitochondrial electron transport chain and a mitochondrially targeted antioxidant (Mito Q) fully prevented the effects of CO. Our data indicate that the cardioprotective effects of HO-1 activity may be attributable to an inhibitory action of CO on cardiac L-type Ca2+ channels. Inhibition arises from the ability of CO to promote generation of reactive oxygen species from complex III of mitochondria. This in turn leads to redox modulation of any or all of three critical cysteine residues in the channel's cytoplasmic C-terminal tail, resulting in channel inhibition.
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This paper introduces scientific research findings and accounts of skilled design judgement to: (i) develop an interdisciplinary account of what affects our identification of letters when reading; (ii) analyse the relationship between the approaches of psychologists and designers to explaining how we identify letters; (iii) propose ways in which collaboration may work to make psychological research more relevant to typographic practice. The topics reviewed are addressed within each discipline and cover the contribution of letters and words to reading; letter features; essential or structural forms; uniformity within font design; and letter spacing. Analysis of the literature identifies possible means of reconciling different perspectives, points out some anomalies in interpretation of findings, and proposes how designers may contribute to research planning and dissemination.
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Seamless phase II/III clinical trials in which an experimental treatment is selected at an interim analysis have been the focus of much recent research interest. Many of the methods proposed are based on the group sequential approach. This paper considers designs of this type in which the treatment selection can be based on short-term endpoint information for more patients than have primary endpoint data available. We show that in such a case, the familywise type I error rate may be inflated if previously proposed group sequential methods are used and the treatment selection rule is not specified in advance. A method is proposed to avoid this inflation by considering the treatment selection that maximises the conditional error given the data available at the interim analysis. A simulation study is reported that illustrates the type I error rate inflation and compares the power of the new approach with two other methods: a combination testing approach and a group sequential method that does not use the short-term endpoint data, both of which also strongly control the type I error rate. The new method is also illustrated through application to a study in Alzheimer's disease. © 2015 The Authors. Statistics in Medicine Published by John Wiley & Sons Ltd.
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FS CMa type stars are a group of Galactic objects with the B[e] phenomenon. They exhibit strong emission-line spectra and infrared excesses, which are most likely due to recently formed circumstellar dust. The group content and identification criteria were described in the first two papers of the series. In this paper we report our spectroscopic and photometric observations of the optical counterpart of IRAS 00470+6429 obtained in 2003-2008. The optical spectrum is dominated by emission lines, most of which have P Cyg type profiles. We detected significant brightness variations, which may include a regular component, and variable spectral line profiles in both shape and position. The presence of a weak Li I 6708 angstrom line in the spectrum suggests that the object is most likely a binary system with a B2-B3 spectral-type primary companion of a luminosity log L/L(circle dot) = 3.9 +/- 0.3 and a late-type secondary companion. We estimate a distance toward the object to be 2.0 +/- 0.3 kpc from the Sun.
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Two new species of Pamphobeteus Pocock 1901 are described from Brazil: Pamphobeteus crassifemur sp. nov. and Pamphobeteus grandis sp. nov.; Pamphobeteus nigricolor, formerly described from Colombia, Ecuador and Bolivia, is recorded from Brazil and its distribution in Ecuador and Bolivia is questioned. A new type of stridulatory organ is described from legs III and IV of P. crassifemur sp. nov. The structure consists of spiniform setae. Stridulation occurs when the spider moves the legs III and IV, sometimes while shedding urticating hairs.
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In this study, we revisited the phylogeography of the three of major DENV-3 genotypes and estimated its rate of evolution, based on the analysis of the envelope (E) gene of 200 strains isolated from 31 different countries around the world over a time period of 50 years (1956-2006). Our phylogenetic analysis revealed a geographical subdivision of DENV-3 population in several country-specific clades. Migration patterns of the main DENV-3 genotypes showed that genotype I was mainly circumspect to the maritime portion of Southeast-Asia and South Pacific, genotype 11 stayed within continental areas in South-East Asia, while genotype III spread across Asia, East Africa and into the Americas. No evidence for rampant co-circulation of distinct genotypes in a single locality was found, suggesting that some factors, other than geographic proximity, may limit the continual dispersion and reintroduction of new DENV-3 variants. Estimates of the evolutionary rate revealed no significant differences among major DENV-3 genotypes. The mean evolutionary rate of DENV-3 in areas with long-term endemic transmissions (i.e., Indonesia and Thailand) was similar to that observed in the Americas, which have been experiencing a more recent dengue spread. We estimated the origin of DENV-3 virus around 1890, and the emergence of current diversity of main DENV-3 genotypes between the middle 1960s and the middle 1970s, coinciding with human population growth, urbanization, and massive human movement, and with the description of the first cases of DENV-3 hemorrhagic fever in Asia. (C) 2008 Elsevier B.V. All rights reserved.
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[Ru-2(dNSAID)(4)Cl] and novel [Ru-2(dNSAID)(4)(H2O)(2)]PF6 complexes, where dNSAID = deprotonated carboxylate from the non-steroidal anti-inflammatory drugs (NSIDs), respectively: ibuprofen, Hibp (1) and aspirin, Hasp (2); naproxen, Hnpx (3) and indomethacin, Hind (4), have been prepared and characterized by optical spectroscopic methods. All of the compounds exhibit mixed valent Ru-2(II, III) cores where metal-metal bonds are stabilized by four drug-carboxylate bridging ligands in paddlewheel type structures. The diruthenium complexes and their parent NSAIDs showed no significant effects for Hep2 human larynx or T24/83 human bladder tumor. In contrast, the coordination of Ru-2(II,III) core led to synergistic effects that increased significantly the inhibition of C6 rat glioma proliferation in relation to the organic NSAIDs naproxen and ibuprofen, The possibility that the complexes Ru-2-ibp and Ru-2-npx may exert effects (anti-angiogenic and anti-matrix metalloprotease) that are similar to those exhibited by NAMI-A opens new horizons for in vivo C6 glioma model studies. (C) 2007 Elsevier Ltd. All rights reserved.
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Abrus pulchellus seeds contain at least seven closely related and highly toxic type 2 ribosome-inactivating pulchellins, each consisting of a toxic A-chain linked to a sugar binding B-chain. In the present study, four pulchellin isoforms (termed P I, P II, P III and P IV) were isolated by affinity, ion exchange and chromatofocusing chromatographies, and investigated with respect to toxicity and sugar binding specificity. Half maximal inhibitory concentration and median lethal dose values indicate that P I and P II have similar toxicities and that both are more toxic to cultured HeLa cells and mice than P III and P IV. Interestingly, the secondary structural characteristics and sugar binding properties of the respective pairs of isoforms correlate well with the two toxicity levels, in that P I/P II and P III/P IV form two specific subgroups. From the deduced amino acids sequences of the four isoforms, it is clear that the highest similarity within each subgroup is found to occur within domain 2 of the B-chains, suggesting that the disparity in toxicity levels might be attributed to subtle differences in B-chain-mediated cell surface interactions that precede and determine toxin uptake pathways.
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Two porous mixed valent diruthenium(II,III)-dicarboxylate compounds have been prepared and characterized by spectroscopic methods, X-ray diffraction and thermogravimetry. Crystalline solids of [Ru(2)(tere)(2)Cl] center dot 3.5H(2)O (tere=terephthalate) and [Ru(2)(adip)(2)Cl] center dot 1.5H(2)O (adip=adipate) consist of extended chains in which polymeric layers of multiply metal-metal bonded [Ru(2)](5+) cores are bridged by dicarboxylate ligands in paddlewheel type geometries. Units of [Ru(2)(dicarboxylate)(2)](n)(+) are linked by axial bridging chloride ions generating three-dimensional networks. The polymers loose non-bonded water molecules at low temperatures but do not undergo thermal decomposition below 280-300 degrees C. Both of compounds exhibit high BET surface areas, [Ru(2)(tere)(2)Cl]: 235 m(2) g(-1) and [Ru(2)(adip)(2)Cl]: 281 m(2) g(-1), and occlude similar numbers of mol of N(2) per mol of metal. The terephthalate ligand generated an organized structure with supermicropores (total pore size of 0.24 cm(3) g(-1)) while the adipate ligand led to a mesoporous structure (total pore sizes of 0.47 cm(3) g(-1)) for the corresponding diruthenium(II,III)-dicarboxylate polymers. (c) 2008 Elsevier B.V. All rights reserved.
Resumo:
Several studies indicate that molecular variants of HPV-16 have different geographic distribution and risk associated with persistent infection and development of high-grade cervical lesions. In the present study, the frequency of HPV-16 variants was determined in 81 biopsies from women with cervical intraepithelial neoplasia grade III or invasive cervical cancer from the city of Belem, Northern Brazil. Host DNAs were also genotyped in order to analyze the ethnicity-related distribution of these variants. Ninie different HPV-16 LCR variants belonging to four phylogenetic branches were identified. Among these, two new isolates were characterized. The most prevalent HPV-16 variant detected was the Asian-American B-2,followed by the European B-12 and the European prototype. Infections by multiple variants were observed in both invasive cervical cancer and cervical intraepithelial neoplasia grade III cases. The analysis of a specific polymorphism within the E6 viral gene was performed in a subset of 76 isolates. The E6-350G polymorphism was significantly more frequent in Asian-American variants. The HPV-16 variability detected followed the same pattern of the genetic ancestry observed in Northern Brazil, with European, Amerindian and African roots. Although African ancestry was higher among women infected by the prototype, no correlation between ethnical origin and HPV-16 variants was found. These results corroborate previous data showing a high frequency of Asian-American variants in cervical neoplasia among women with multiethnic origin.
Resumo:
The anchoring of K[Ru-III(edta)(Cl)] on poly(amidoamine) dendrimers (PAMAM of three generations G(x)/Ru (x = 0, 2 and 3)) through a peptide type bond yielded the aquo species, [Ru-III(edta)(H2O)] on dendrimer surface, and upon NO exposure, yielded their nitrosyl analogues, Gx/RuNO. Characterization of these compounds by elemental analysis, and a UV-vis, IR and C-13 NMR spectroscopies indicated the immobilization of 4,12 and 29 molecules of [Ru-III(edta)(H2O)](-) or of the nitrosyl complex [Ru(II)edta)NO] on the dendrimer surface for G(X) = 0, 2 and 3, respectively. For each complex the electrochemical spectrum presented only one redox process with redox potential values of -0.20 and -0.32 V(vs SCE) attributed to the Ru/Run and NO+/NO0 couples in G(x)/Ru and G./RuNO, respectively. The one-electron reduction of Gx/RuNO` generates Gx/RuNOo, which undergoes aquation with a k(-NO) of 2.1 +/- 0.7 x 10(-3) s(-1) (pH 1.0, mu = 0.2 mol/L, CF3COOH/NaCF3COO, 25 degrees C). The Gx/RuNO species induced a relaxing effect in aortic rings denuded of endothelium and exhibited in vitro assay trypanocidal activity. (c) 2008 Elsevier Inc. All rights reserved.
Resumo:
The complex of Brookhart Ni(α-diimine)Cl2 (1) (α-diimine = 1,4-bis(2,6- diisopropylphenyl)-acenaphthenediimine) has been characterized after impregnation on silica (S1) and MAO-modified silicas (4.0, 8.0 and 23.0 wts.% Al/SiO2 called S2, S3 and S4, respectively). The treatment of these heterogeneous systems with MAO produces some active catalysts for the polymerization of the ethylene. A high catalytic activity has been gotten while using the system supported 1/S3 (196 kg of PE/mol[Ni].h.atm; toluene, Al/Ni = 1000, 30ºC, 60 min and atmospheric pressure of ethylene). The effects of polymerization conditions have been tested with the catalyst supported in S2 and the best catalytic activity has been gotten with solvent hexane, MAO as cocatalyst, molar ratio Al/Ni of 1000 and to the temperature of 30°C (285 kg of PE/mol[Ni].h.atm). When the reaction has been driven according to the in situ methodology, the activity practically doubled and polymers showed some similar properties. Polymers products by the supported catalysts showed the absence of melting fusion, results similar to those gotten with the homogeneous systems by DSC analysis. But then, polymers gotten with the transplanted system present according to the GPC’s curves the polydispersity (MwD) varies between 1.7 and 7.0. A polyethylene blend (BPE/LPE) was prepared using the complex Ni(α-diimine)Cl2 (1) (α-diimine = 1,4-bis(2,6-diisopropylphenyl)-acenaphthenediimine) and {TpMs*}TiCl3 (2) (TpMs* = hydridobis(3-mesitylpyrazol-1-yl)(5-mesitylpyrazol-1-yl)) supported in situ on MAO-modified silica (4.0 wts. -% Al/SiO2, S2). Reactions of polymerization of ethylene have been executed in the toluene in two different temperatures (0 and 30°C), varying the molars fraction of nickel (xNi), and using MAO as external cocatalyst. To all temperatures, the activities show a linear variation tendency with xNi and indicate the absence of the effect synergic between the species of nickel and the titanium. The maximum of activity have been found at 0°C. The melting temperature for the blends of polyethylene produced at 0 °C decrease whereas xNi increases indicating a good compatibility between phases of the polyethylene gotten with the two catalysts. The melting temperature for the blends of polyethylene showed be depend on the order according to which catalysts have been supported on the MAO-modified silica. The initial immobilization of 1 on the support (2/1/S2) product of polymers with a melting temperature (Tm) lower to the one of the polymer gotten when the titanium has been supported inicially (1/2/S2). The observation of polyethylenes gotten with the two systems (2/1/S2 and 1/2/S2) by scanning electron microscopy (SEM) showed the spherical polymer formation showing that the spherical morphology of the support to been reproduced. Are described the synthesis, the characterization and the catalytic properties for the oligomerization of the ethylene of four organometallics compounds of CrIII with ligands ([bis[2-(3,5-dimethyl-1-pyrazolyl)ethyl]amine] chromium (III) chloride (3a), [bis[2-(3,5- dimethyl-l-pyrazolyl)ethyl]benzylamine] chromium (III) chloride (3b), [bis[2-(3,5-dimethyl-lpyrazolyl) ethyl]ether] chromiun(III)chloride (3c), [bis[2-(3-phenyl-lpyrazolyl) ethyl]ether]chromiun(III)chloride (3d)). In relation of the oligomerization, at exception made of the compounds 3a, all complex of the chromium showed be active after activation with MAO and the TOF gotten have one effect differentiated to those formed with CrCl3(thf)3. The coordination of a tridentate ligand on the metallic center doesn't provoke any considerable changes on the formation of the C4 and C6, but the amount of C8 are decrease and the C10 and C12+ have increased. The Polymers produced by the catalyst 3a to 3 and 20 bar of ethylene have, according to analyses by DSC, the temperatures of fusion of 133,8 and 136ºC respectively. It indicates that in the two cases the production of high density polyethylene. The molar mass, gotten by GPC, is 46647 g/mols with MwD = 2,4 (3 bar). The system 3c/MAO showed values of TOF, activity and selectivity to different α-olefins according to the pressure of ethylene uses. Himself that shown a big sensibility to the concentration of ethylene solubilized.
Resumo:
A presente tese pretende contribuir criticamente para o entendimento das intrincadas relações existentes entre o Estado, o capital e a produção acadêmica. Para isso, se propôs a interpretar as relações acadêmicas de produção na pós-graduação em Administração no Brasil articulando-as com categorias analíticas mais amplas, delineadas de forma a fornecer um quadro, ao fundo, da economia-política. O pressuposto de que a atual intensificação dos ritmos de produção acadêmica contrasta com um passado – idealizado – de ciência contemplativa precisou ser confrontado com o desenvolvimento histórico da educação superior e da pós-graduação no país objetivando-se demover certas mitificações do debate. O Estado, em sua versão reformada a partir do ideário friedmaniano, o conceito de capital monopolista e a teoria do processo de trabalho forneceram suporte teórico-metodológico – e empírico – para a interpretação do quadro político-econômico proposto. Para a passagem do geral para o particular – das conexões entre o Estado e o capital à produção acadêmica – recorreu-se à coleta de dados em duas frentes: (i) analisou-se a produção acadêmica de todos os 168 pesquisadores-doutores bolsistas (até março de 2014) em Produtividade em Pesquisa (PQ) do CNPq na área de Administração e (ii) realizou-se entrevistas em profundidade com pesquisadores-doutores e doutorandos dos mais variados programas de pós-graduação em Administração do país. Os resultados foram inquietantes: verificou-se que está em curso um processo de intensificação da incorporação da mão-de-obra formada por alunos-orientandos às estruturas pedagógico-produtivas dos cursos de pós-graduação. Os orientandos respondem pela parcela mais substantiva do total da produção acadêmica, enquanto que os processos de trabalho aprofundam re-significações das atribuições dos cursos de pós-graduação e intensificam a divisão do trabalho, com impactos diversos nas relações entre os sujeitos da pós-graduação. Quando se procede ao movimento analítico inverso – das relações no interior da pós-graduação em Administração no Brasil para o quadro da economia-política posicionado ao fundo – observa-se que o Estado (principalmente através da CAPES e do CNPq) e o mercado capitalista acadêmico (tendendo a poucas empresas de capital monopolista) acrescentam determinações fundamentais às relações acadêmicas de produção. Índices de avaliação baseados em métricas de contabilidade da pesquisa se legitimam como monopólios epistemológicos da qualidade e se institucionalizam pelas ações coordenadas da CAPES e do CNPq no conjunto do sistema oficial de pós-graduação. Metas de produção são estabelecidas e re-significadas pelos sujeitos. No limite, define-se até mesmo o tipo de ciência que se produz na área. Conclui-se que a resistência aos atuais padrões intensificados de produção acadêmica passa pelo entendimento crítico de todas essas relações que se costuram e se estruturam no interior da pós-graduação.