1,721,013 research outputs found

    THE STENO HYPOTHESIS FOR CARDIOVASCULAR AND RENAL DISEASE REVISITED.

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    Heparansulfate is proposed as a key player in the pathogenesis of diabetic nephropath

    Retrograde signaling and photoprotection in a gun4 mutant of Chlamydomonas reinhardtii.

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    GUN4 is a regulatory subunit of Mg-chelatase involved in the control of tetrapyrrole synthesis in plants and cyanobacteria. Here, we report the first characterization of a gun4 insertion mutant of the unicellular green alga Chlamydomonas reinhardtii. The mutant contains 50% of chlorophyll as compared to wild-type and accumulates ProtoIX. In contrast to the increase in LHC transcription, the accumulation of most LHC proteins is drastically diminished, implying posttranscriptional down-regulation in the absence of transcriptional coordination. We found that 803 genes change their expression level in gun4 as compared to wild-type, by RNA-Seq, and this wide-ranging effect on transcription is apparent under physiological conditions. Besides LHCs, we identified transcripts encoding enzymes of the tetrapyrrole pathway and factors involved in signal transduction, transcription, and chromatin remodeling. Moreover, we observe perturbations in electron transport with a strongly decreased PSI-to-PSII ratio. This is accompanied by an enhanced activity of the plastid terminal oxidase (PTOX) that could have a physiological role in decreasing photosystem II excitation pressure

    Heparin modulates proliferation and proteoglycans biosynthesis in murine mesangial cells: molecular clues for its activity in nephropathy

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    Glycosaminoglycan administration has favourable effects on morphological and functional renal abnormalities in different models. The possibility that exogenous glycosaminoglycans modulate glomerular matrix synthesis was explored in both primary and SV40-MES13 murine mesangial cell cultures. On both cell types, both low-molecular-weight heparin and different glycosaminoglycans showed dose-dependent inhibition of proliferation and increase of 35SO4(2)-uptake. After 36 h the cell compartment contained a spectrum of 35S-molecules of less than 200 kDa; under heparin treatment, the two main 35SO4(2)-components (high and medium MW) increased by 16 and 37% respectively. Susceptibility to glycosidases revealed that heparin promotes the expression of heparan sulphate and increases that of chondroitin sulphate. Moreover, heparin modifies the expression of decorin and biglycan, involved in adhesion and fibrillogenesis, while not affecting perlecan. The extracellular matrix modulation in renal cells, for which the sulphation type and ratio of heparin are crucial, may thus explain the beneficial renal effects of heparin

    Going Beyond Counting First Authors in Author Co-citation Analysis

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    The present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed

    Variations on the Author

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    “Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship

    Appropriate Similarity Measures for Author Cocitation Analysis

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    We provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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