1,720,959 research outputs found
Sirtuin-mediated DNA damage response by modulation of glutamate dehydrogenase activity in Arabidopsis thaliana
No full textSirtuins, ClassIII NAD-dependent deacetylases, play a central role in
many metabolic pathways related to cell survival and are evolutionary
conserved from bacteria to mammals. Among the seven human sirtuins,
SIRT4 and SIRT6 share homology domains with the two sirtuins present
in Arabidopsis thaliana plants, AtSRT2 and AtSRT1 respectively.
With the aim to evaluate sirtuin functions in phylogenetically
distant organisms, we report data on a corresponding role between
Arabidopsis SRT2 and human SIRT4 genes. We find that AtSRT2
is involved in a defence process already known to be regulated
by SIRT4. In fact the DNA Damage Response (DDR) in human
cells induces SIRT4 that in turn limits proliferation via repression
of glutamine metabolism (Jeong et al, Cancer Cell 2013, 23:450).
In Arabidopsis seedlings, the induction of DNA damage promotes
transcriptional activation of SRT2 gene and decreased activity of glutamate
dehydrogenase (GDH), one of the enzymes that catalyze a-ketoglurate
(aKG) production from glutamine. As aKG is a major anaplerotic
component of TCA cycle in proliferating cells, the decreased GDH
activity is coherent with the slowed cell proliferation that we observed.
Moreover, in plants knock out for SRT2, GDH activity and cell
proliferation are less affected by DNA damage, confirming the role of
AtSRT2 in this metabolic pathway
Neonatal osteomyelitis of the talus due to methicillin-resistant Staphylococcus epidermidis
No full textAcute osteomyelitis is a relatively rare disorder in the neonatal period, with considerable morbidity and mortality. Early diagnosis and prompt treatment are essential for a successful outcome. In this report we present a case of acute osteomyelitis of the talus due to methicillin-resistant Staphylococcus epidermidis, observed in a 30-day-old infan
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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