1,720,986 research outputs found
Sex effect on presenilins expression in post-natal rat brain
No full textPresenilin 1 and presenilin 2 are widely expressed during brain development. Several mutations in these proteins have been associated with autosomal-domi- nant inherited forms of Alzheimer disease. Their ex- pression is regulated by various cellular and ex- tracellular factors, which change with age and sex. Both age and sex are key risk factors for Alzheimer’s disease, but the issue of whether the expression of presenilins is influenced by the sex during early post- natal development of the brain has been poorly inves- tigated so far. In this study, we report that transcript levels of presenilins, and the subset of neurons ex- pressing these proteins in various brain areas of the developing post-natal brain are different in male and female rats, suggesting that their function(s) may contribute to sexual dimorphism in the brain, both at morphological and functional level
Thapsigargin affects presenilin-2 but not presenilin-1 regulation in SK-N-BE cells
No full textPresenilin-1 (PS1) and presenilin-2 (PS2) are transmembrane proteins widely expressed in the central nervous system, which
function as the catalytic subunits of g-secretase, the enzyme that releases amyloid-b protein (Ab) from ectodomain cleaved
amyloid precursor protein (APP) by intramembrane proteolysis. Mutations in PS1, PS2, and Ab protein precursor are involved
in the etiology of familial Alzheimer’s disease (FAD), while the cause of the sporadic form of AD (SAD) is still not known. However,
since similar neuropathological changes have been observed in both FAD and SAD, a common pathway in the etiology of the
disease has been suggested. Given that age-related deranged Ca2þ regulation has been hypothesized to play a role in SAD
pathogenesis via PS gene regulation and g-secretase activity, we studied the in vitro regulation of PS1 and PS2 in the human
neuron-like SK-N-BE cell line treated with the specific endoplasmic reticulum (ER) calcium ATPase inhibitor Thapsigargin (THG), to
introduce intracellular Ca2þ perturbations and mimic the altered Ca2þ homeostasis observed in AD. Our results showed a consistent
and significant down-regulation of PS2, while PS1 appeared to be unmodulated. These events were accompanied by
oxidative stress and a number of morphological alterations suggestive of the induction of apoptotic machinery. The administration
of the antioxidant N-acetylcysteine (NAC) did not revert the THG-induced effects reported, while treatment with the Ca2þ-independent
ER stressor Brefeldin A did not modulate basal PS1 and PS2 expression. Collectively, these results suggest that Ca2þ
fluctuation rather than ER stress and/or oxidative imbalance seems to play an essential role in PS2 regulation and confirm that,
despite their strong homology, PS1 and PS2 could play different roles in AD
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
Variations 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
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe 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
Get PDFWe 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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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