1,720,955 research outputs found
Ascorbate Deficiency Accelerates Neuropathology in Alzheimer's Disease
Get PDFSubclinical ascorbate deficiency is widespread in many populations, but its role in both Alzheimer’s disease and normal aging is understudied. We decreased brain ascorbate in the APPSWE/PSEN1deltaE9 mouse model of Alzheimer’s disease by crossing APP/PSEN1+ bigenic mice with SVCT2+/- heterozygous knockout mice, which have lower expression of the sodium-dependent vitamin C transporter required for neuronal ascorbate transport. At 6 months, SVCT2+/- and APP/PSEN1 mice and the combination genotype SVCT2+/-;APP/PSEN1 were impaired on multiple tests of cognitive ability and exhibited increased oxidative stress in the brain. Increased amyloid plaque burden was observed in SVCT2 +/-;APP/PSEN1 mice compared to APP/PSEN1 mice at 14 months. At 4 months of age, during what is considered a prodromal stage in mouse models of Alzheimer’s disease, mitochondria isolated from SVCT2+/- and APP/PSEN1 mice showed disruptions in oxygen consumption and mitochondrial respiration with opposing directionality indicating that different pathways were being affected. Both groups had significant increases in the production of reactive oxygen species. Additionally, genes commonly associated with Alzheimer’s disease pathology and progression were up-regulated in SVCT2+/-;APP/PSEN1 mice and APP/PSEN1, with a greater magnitude of gene expression change in SVCT2+/-;APP/PSEN1 mice. Furthermore, 5-hydroxymethylcytosine levels, indicative of epigenetic modification, were significantly increased compared to wild type at 4 months. There were differing patterns of gene expression based on SVCT2+/- and APP/PSEN1 status, as well as with age, suggesting an age-related change in gene expression occurs earlier in APP/PSEN+ groups and is exacerbated in combination with ascorbate deficiency. These data support the hypothesis that even moderate ascorbate deficiency plays an important role in accelerating amyloid pathogenesis, particularly during early stages of disease development, and that oxidative stress pathways likely modulate these effects
Ascorbate Deficiency Accelerates Neuropathology in Alzheimer's Disease
No full textSubclinical ascorbate deficiency is widespread in many populations, but its role in both Alzheimer’s disease and normal aging is understudied. We decreased brain ascorbate in the APPSWE/PSEN1deltaE9 mouse model of Alzheimer’s disease by crossing APP/PSEN1+ bigenic mice with SVCT2+/− heterozygous knockout mice, which have lower expression of the sodium-dependent vitamin C transporter required for neuronal ascorbate transport. At 6 months, SVCT2+/− and APP/PSEN1 mice and the combination genotype SVCT2+/−;APP/PSEN1 were impaired on multiple tests of cognitive ability and exhibited increased oxidative stress in the brain. Increased amyloid plaque burden was observed in SVCT2+/−;APP/PSEN1 mice compared to APP/PSEN1 mice at 14 months. At 4 months of age, during what is considered a prodromal stage in mouse models of Alzheimer’s disease, mitochondria isolated from SVCT2+/− and APP/PSEN1 mice showed disruptions in oxygen consumption and mitochondrial respiration with opposing directionality indicating that different pathways were being affected. Both groups had significant increases in the production of reactive oxygen species. Additionally, genes commonly associated with Alzheimer’s disease pathology and progression were up-regulated in SVCT2+/−;APP/PSEN1 mice and APP/PSEN1, with a greater magnitude of gene expression change in SVCT2+/−;APP/PSEN1 mice. Furthermore, 5-hydroxymethylcytosine levels, indicative of epigenetic modification, were significantly increased compared to wild type at 4 months. There were differing patterns of gene expression based on SVCT2+/− and APP/PSEN1 status, as well as with age, suggesting an age-related change in gene expression occurs earlier in APP/PSEN+ groups and is exacerbated in combination with ascorbate deficiency. These data support the hypothesis that even moderate ascorbate deficiency plays an important role in accelerating amyloid pathogenesis, particularly during early stages of disease development, and that oxidative stress pathways likely modulate these effects
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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