130,384 research outputs found
Periostin induces proliferation of differentiated cardiomyocytes and promotes cardiac repair
No full textAdult mammalian hearts respond to injury with scar formation and not with cardiomyocyte proliferation, the cellular basis of regeneration. Although cardiogenic progenitor cells may maintain myocardial turnover, they do not give rise to a robust regenerative response. Here we show that extracellular periostin induced reentry of differentiated mammalian cardiomyocytes into the cell cycle. Periostin stimulated mononucleated cardiomyocytes to go through the full mitotic cell cycle. Periostin activated alphaV, beta1, beta3 and beta5 integrins located in the cardiomyocyte cell membrane. Activation of phosphatidylinositol-3-OH kinase was required for periostin-induced reentry of cardiomyocytes into the cell cycle and was sufficient for cell-cycle reentry in the absence of periostin. After myocardial infarction, periostin-induced cardiomyocyte cell-cycle reentry and mitosis were associated with improved ventricular remodeling and myocardial function, reduced fibrosis and infarct size, and increased angiogenesis. Thus, periostin and the pathway that it regulates may provide a target for innovative strategies to treat heart failure
In vivo cardiac gene transfer of Kv4.3 abrogates the hypertrophic response in rats after aortic stenosis
No full textBACKGROUND:
Prolongation of the action potential duration (APD) and decreased transient outward K+ current (I(to)) have been consistently observed in cardiac hypertrophy. The relation between electrical remodeling and cardiac hypertrophy in vivo is unknown.
METHODS AND RESULTS:
We studied rat hearts subjected to pressure overload by surgical ascending aortic stenosis (AS) and simultaneously infected these hearts with an adenovirus carrying either the Kv4.3 gene (Ad.Kv4.3) or the beta-galactosidase gene (Ad.beta-gal). I(to) density was reduced and APD50 was prolonged (P<0.05) in AS rats compared with sham rats. Kv4.2 and Kv4.3 expressions were decreased by 58% and 51%, respectively (P<0.05). AS rats infected with Ad.beta-gal developed cardiac hypertrophy compared with sham rats, as assessed by cellular capacitance and heart weight-body weight ratio. Associated with the development of cardiac hypertrophy, the expression of calcineurin and its downstream transcription factor nuclear factor of activated T cells (NFAT) c1 was persistently increased by 47% and 36%, respectively (P<0.05) in AS myocytes infected with Ad.beta-gal compared with sham myocytes. In vivo gene transfer of Kv4.3 in AS rats was shown to increase Kv4.3 expression, increase I(to) density, and shorten APD50 by 1.6-fold, 5.3-fold, and 3.6-fold, respectively (P<0.05). Furthermore, AS rats infected with Ad.Kv4.3 showed significant reductions in calcineurin and NFAT expression. (P<0.05).
CONCLUSIONS:
Downregulation of I(to), APD prolongation, and cardiac hypertrophy occur early after AS, and in vivo gene transfer of Kv4.3 can restore these electrical parameters and abrogate the hypertrophic response via the calcineurin pathway
MeSH term explosion and author rank improve expert recommendations
No full textInformation overload is an often-cited phenomenon that reduces the productivity, efficiency and efficacy of scientists. One challenge for scientists is to find appropriate collaborators in their research. The literature describes various solutions to the problem of expertise location, but most current approaches do not appear to be very suitable for expert recommendations in biomedical research. In this study, we present the development and initial evaluation of a vector space model-based algorithm to calculate researcher similarity using four inputs: 1) MeSH terms of publications; 2) MeSH terms and author rank; 3) exploded MeSH terms; and 4) exploded MeSH terms and author rank. We developed and evaluated the algorithm using a data set of 17,525 authors and their 22,542 papers. On average, our algorithms correctly predicted 2.5 of the top 5/10 coauthors of individual scientists. Exploded MeSH and author rank outperformed all other algorithms in accuracy, followed closely by MeSH and author rank. Our results show that the accuracy of MeSH term-based matching can be enhanced with other metadata such as author rank
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
Dispelling the Myths Behind First-author Citation Counts
No full textWe 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
Scholarly Communication and Publishing Lunch and Learn Talk #11: The ULS Open Access Author Fee Fund
No full textAt the May 2014 talk, you will learn about the ULS Open Access Author Fee Fund--what it is, why we do it, how it works, and how the program is going so far
The R&D Tax Incentives
No full textThis article sets out some background information and reflections of the author on the R&D tax incentive schemes included in the Common Corporate Tax Base (CCTB) Proposal. In particular the author analyzes the stimulus to private R&D through ad hoc tax incentives included in the CCTB Proposal and dives into the actual provisions included in the Proposal highlighting the most relevant issues connected with their design and interpretation. Moreover, the author explores the interaction between the CCTB Proposal and the granting by Member States of domestic R&D tax incentives
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