1,720,972 research outputs found
Prenatal exposure to carbon monoxide temporarily impairs maturation of rat cardiomyocytes: Electrophysiological evidence
No full text
Heart rate reduction with ivabradine prevents the global phenotype of left ventricular remodeling.
No full textThe aim of this study was to investigate the effect of chronic heart rate (HR) reduction with the hyperpolarization-activated current inhibitor ivabradine on the global phenotype of left ventricular (LV) remodeling in a ligated rat model. Seven days after coronary artery ligation, Wistar rats received ivabradine (10 mg · kg(-1) · day(-1) administered in drinking water) [myocardial infarction + ivabradine (MI+IVA), n = 22] or vehicle only (drinking water) (MI, n = 20) for 90 days. A sham group (n = 20) was included for model validation. MI+IVA rats had 12% lower HR (P < 0.01), improved LV volumes, 15% higher LV ejection fraction (LVEF, P < 0.01) than MI rats, and 33% reductions in both plasma atrial natriuretic peptide (ANP, P = 0.052) and cardiac hydroxyproline. Using patch-clamp, action potential duration was reduced and transient outward current density increased (P < 0.05). Cardiac energy metabolism was also improved (+33% creatine phosphate, P < 0.001; +15% ATP; and +9% energy charge, P < 0.05). Significant correlations were found between HR and parameters of cardiac metabolism, ANP, and LVEF (all P < 0.05). The HR-reducing properties of ivabradine prevent changes in the global phenotype of LV remodeling in the rat, optimize energy consumption, and avoid electrophysiological and structural remodeling
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
Heart Rate Reduction Prevents The Global Phenotype Of Post-myocardial LV Infarction Remodeling
No full textRationale LV remodeling is a crucial phenomenon of adaptation/maladaptation to heart diseases and plays a major role in HF progression after myocardial infarction. We tested if in a post-MI rat model, a pure HR reduction by ivabradine (IVA) is able to modulate structural and electrophysiological remodeling processes.
Methods IVA (10 mg/kg/d) was given in drinking water for 3 months to Wistar rats, 7 days after LAD ligation (MI). SHAM rats (n = 14) were used as control (untreated; n = 14) or for electrophysiology (IVA; n = 7). MI rats were randomly allocated to IVA (n = 17) or vehicle (n = 15). At 3 months, end-diastolic volume (EDV), end-systolic volume (ESV) and EF were evaluated by echocardiography. BNP was tested in plasma by IEA. IVA effect on transient K+ outward current (Ito), the main current changed in HF, was recorded in single LV myocyte (LVM) in whole-cell configuration by applying a voltage protocol activation. OH-proline, an indirect index of collagen content in LV, was measured by spectrophotometry (n = 6/group).
Results Echocardiography: At 3 months, in MI, IVA significantly reduced HR (208 ± 5 bpm vs. 235 ± 4, p < 0.05). ESV increased in MI vs. control SHAM (0.78 ± 0.10 vs. 0.41 ± 0.03 ml) while it was significantly reduced by IVA (0.54 ± 0.1 ml, p < 0.05). As there is no effect on EDV, IVA improved EF (62.8 ± 1.7 vs. 54.7 ± 2.3%, p < 0.05) in MI. Neuroendocrine response. Circulating BNP significantly increased in MI vs. control SHAM (2.2 ± 0.2 vs. 1.4 ± 0.1 ng/ml, p < 0.01) and tended to be reduced in MI treated rats. Electrophysiology: IVA did not change peak Ito density measured at +50 mV in LVMs from SHAM. Significantly reduced in LVMs from MI untreated rats (5.1 ± 0.7 pA/pF, n = 30, p < 0.01) vs. SHAM, peak Ito was partially restored in LVMs from MI treated rats (7.3 ± 0.8 pA/pF, n = 28, p < 0.05). Interstitial remodeling: IVA significantly reduced OH-proline content in MI vs. control SHAM (9.03 ± 1.93 vs. 14.85 ± 1.70 μg/mg dry weight, p < 0.05), which is significantly correlated with infarct scare (r = 0.887, p = 0.0001) and HR (r = 0.593, p < 0.05).
Conclusions HR reduction by IVA prevents electrophysiological as well as mechanical, cellular and interstitial alteration during post-MI LV remodeling. These results reinforce the potential interest of HR reduction in HF management
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
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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