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Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Activity and fluorescence changes of euphorbia peroxidase in the presence of trifluoroethanol
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Cell-autonomous decrease in proliferative competitiveness of the aged hepatocyte
No full textBackground & Aims The regenerative potential of the liver declines with age, this might be dependent on a decrease in the intensity of the stimulus and/or an increased refractoriness of the target. In the present study, we compared the in vivo growth capacity of young and old hepatocytes transplanted into the same host. Methods We utilized the retrorsine (RS)-based model for liver repopulation, which provides a specific and effective stimulus for transplanted hepatocytes. Rats of the dipeptidyl-peptidase type IV (DPP-IV)-deficient strain were given RS and were injected with a mix of hepatocytes isolated from either a 2-month old or an 18-month old donor. To follow the fate of transplanted cells, they were each identified through a specific tag: young hepatocytes expressed the green fluorescent protein (GFP+), while those from old donors were DPP-IV-positive. Results At 1 month post-transplantation, DPP-IV-positive clusters (derived from old donor) were consistently smaller than those GFP+ (young donor); the cross sectional area of clusters was decreased by 50%, while the mean volume was reduced to 1/3. Furthermore, when 2/3 partial hepatectomy (PH) was performed, the S-phase response of old hepatocyte-derived clusters was only 30-40% compared to that observed in cluster originating from young hepatocytes. No markers of cell senescence were expressed in clusters of transplanted hepatocytes. Conclusions This is the first direct evidence in vivo that hepatocytes in the aged liver express a cell-autonomous decline in their replicative capacity and in their regenerative response to PH compared to those from a young animal
Activity and structural changes of Euphorbia characias peroxidase in the presence of trifluoroethanol
No full textActivity assays, conformational changes and transitional switches between secondary structures of a peroxidase from Euphorbia characias were studied in the presence of trifluoroethanol and in the presence or absence of calcium ions. The addition of trifluoroethanol up to 10-20% first induced a drastic decrease of alpha-helix content followed by an increase of tryptophan fluorescence emission intensity, a progressive re-induction of the formation of alpha-helical elements concomitant with loss of enzyme activity. In the presence of calcium ions, the fluorescence of the enzyme almost remained unchanged in the trifluoroethanol concentration range 5-20%. Further increase in trifluoroethanol concentration led to a protein structure characterized by a progressive re-induction of alpha-helical elements, a remarkable increase of the tryptophan fluorescence and a loss of enzyme activity. These results indicate that calcium ions in Euphorbia peroxidase play an essential role in maintaining the hydrophobic interactions on the protein structure preserving enzymatic activity
Daxx è una nuova proteina interagente con AIRE coinvolta nella patogenesi della poliendocrinopatia autoimmune di tipo I
No full textL’importanza dell’analisi molecolare del gene AIRE nella diagnosi precoce di poliendocrinopatia autoimmine di tipo I
No full textVariations on the Author
Get PDF“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
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