935 resultados para International Institute for Applied Systems Analysis


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Acknowledgements We would like to thank Cochrane Work Trials Search Co-ordinators Leena Isotalo and Kaisa Neuvonen for developing the search strategy and Managing Editor Jani Ruotsalainen and Co-ordinating Editor Jos Verbeek for editing the text and providing helpful comments. We would also like to thank Richard Othieno for his contributions to the protocol.

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Funding This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme.

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Acknowledgements This article was based on the first author’s PhD which was financed by the Malawi Health Research Capacity Strengthening Initiative. We thank Mr Patrick Naphini formerly of the Ministry of Health and Mrs Mafase Sesani at CHAM Secretariat for helping with the data. We also thank Mr Jacob Mazalale for useful comments on the article.

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Acknowledgements This work was supported by the UK Energy Research Centre Phase 2, under its Energy and Environment theme Grant Number NE/J005924/1 and NE/G007748/1. Open Access funded by Natural Environment Research Council

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Although microtubules (MTs) are generally thought to originate at the centrosome, a number of cell types have significant populations of MTs with no apparent centrosomal connection. The origin of these noncentrosomal MTs has been unclear. We applied kinetic analysis of MT formation in vivo to establish their mode of origin. Time-lapse fluorescence microscopy demonstrated that noncentrosomal MTs in cultured epithelial cells arise primarily by constitutive nucleation at, and release from, the centrosome. After release, MTs moved away from the centrosome and tended to depolymerize. Laser-marking experiments demonstrated that released MTs moved individually with their plus ends leading, suggesting that they were transported by minus end-directed motors. Released MTs were dynamic. The laser marking experiments demonstrated that plus ends of released MTs grew, paused, or shortened while the minus ends were stable or shortened. Microtubule release may serve two kinds of cellular function. Release and transport could generate the noncentrosomal MT arrays observed in epithelial cells, neurons, and other asymmetric, differentiated cells. Release would also contribute to polymer turnover by exposing MT minus ends, thereby providing additional sites for loss of subunits. The noncentrosomal population of MTs may reflect a steady-state of centrosomal nucleation, release, and dynamics.

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The Escherichia coli MG1655 genome has been completely sequenced. The annotated sequence, biochemical information, and other information were used to reconstruct the E. coli metabolic map. The stoichiometric coefficients for each metabolic enzyme in the E. coli metabolic map were assembled to construct a genome-specific stoichiometric matrix. The E. coli stoichiometric matrix was used to define the system's characteristics and the capabilities of E. coli metabolism. The effects of gene deletions in the central metabolic pathways on the ability of the in silico metabolic network to support growth were assessed, and the in silico predictions were compared with experimental observations. It was shown that based on stoichiometric and capacity constraints the in silico analysis was able to qualitatively predict the growth potential of mutant strains in 86% of the cases examined. Herein, it is demonstrated that the synthesis of in silico metabolic genotypes based on genomic, biochemical, and strain-specific information is possible, and that systems analysis methods are available to analyze and interpret the metabolic phenotype.

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We applied mutational analysis to a protein domain that functions in neither catalysis nor binding but, rather, in transmembrane signaling. The domain is part of chemoreceptor Trg from Escherichia coli. It contains four transmembrane segments, two from each subunit of the homodimer. We used cysteine scanning to investigate the functional importance of each of 54 residues in the two transmembrane segments. Cysteines at some positions resulted in subtle but significant reductions in tactic response. Those positions defined a specific helical face on each segment, implying that the segments function as helices. The functionally important faces corresponded to structural, helical packing faces identified independently by biochemical studies. All functionally impaired receptors exhibited altered signaling properties, either reduced signaling upon stimulation or induced signaling in the absence of stimulation. The distribution of substitutions creating these two phenotypes implied that conformational signaling involves movement between the two transmembrane helices within a subunit and that signaling is optimal when stable interactions are maintained across the interface between subunits.

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Peer reviewed

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FUNDING Biotechnology and Biological Sciences Research Council (BBSRC) [BB/I020926/1 to I.S.]; BBSRC PhD studentship award [C103817D to I.S. and M.C.R.]; Scottish Universities Life Science Alliance PhD studentship award (to M.C.R. and I.S.]. Funding for open access charge: BBSRC. Conflict of interest statement. None declared.

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This work was supported by the Brazilian agencies FAPESP and CNPq. MSB also acknowledges the Engineering and Physical Sciences Research Council grant Ref. EP/I032606/1. GID thanks Felipe A. C. Pereira for fruitful discussions.

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O objetivo do presente trabalho foi caracterizar as propriedades superficiais de filmes à base de gelatina. Para o qual foram elaborados filmes de: (i) Gelatina plastificado com glicerol (G) (gelatina: 5 g/100 g SFF; glicerol: 30 g/100 g de gelatina), (ii) Gelatina reforçado com montmorilhonita (G/MMT) (gelatina: 5 g/100 g SFF; glicerol: 30 g/100 g de gelatina; MMT: 5 g/100 g de gelatina) e Gelatina plastificado com citrato de acetiltributila (G/ATB) (gelatina: 5 g/100 g SFF; ATB: 50 g/100 de gelatina; lecitina de soja: 60 g/100 g de ATB; etanol: 20 g/100 g SFF). Os filmes foram produzidos mediante o uso de um aplicador automático de filmes \"Spreading\". Logo, os filmes foram submetidos a testes para determinação da espessura, umidade e propriedades óticas (brilho, cor e opacidade). Também foi caracterizada a microestrutura por microscopia eletrônica de varredura (MEV) e microscopia de força atômica (AFM); às imagens obtidas por MEV foi aplicado um analise de imagem mediante o programa Image J, para obter o valor da dimensão fractal (DF). Depois foram caracterizadas as propriedades superficiais de ângulo de contato (AC), molhabilidade ou coeficiente de espalhamento (Se), e energia livre superficial (ELS) mediante a medida do ângulo de contato pelo método da gota séssil (água: 5 µL e 1-Bromonaftaleno: 3 µL). Para o cálculo da ELS também foi aplicado o método de Owens-Wendt. Estas caracterizações foram feitas em ambos os lados do filme, lado ar e lado placa. A natureza do filme de G/ATB influenciou na umidade e as propriedades óticas, enquanto que os filmes de G e G/MMT apresentaram características similares. Em relação à microestrutura e rugosidade, o filme de G apresentou a superfície mais homogênea e lisa, contrario ao observado no filme de G/MMT, que apresentou a maior rugosidade seguida do filme de G/ATB. Foi observado que houve uma relação entre os valores de rugosidade e DF. De acordo com o valor do AC, os filmes apresentaram um caráter hidrofóbico, pois seus valores foram superiores a 65° (em ambos os lados dos filmes), na seguinte ordem: G/MMT > G > G/ATB; sendo que o Se seguiu a mesma tendência. Cabe mencionar também que não foi encontrada uma correlação significativa entre os valores de AC e rugosidade. Em função dos valores de AC, Se e ELS (especificamente a componente polar), o filme de G/ATB apresentou o menor caráter hidrofóbico, pois apresentou menores valores de AC e maiores valores de Se em comparação com os outros dois filmes. Os valores da componente polar da G/ATB foram os maiores, explicando de melhor maneira o caráter menos hidrofóbico deste filme. Pode-se concluir que os filmes à base de gelatina elaborados no presente trabalho têm propriedades hidrofóbicas (AC>65°), sendo a G/MMT o filme com melhores características hidrofóbicas.