1,720,966 research outputs found
Future strategies of reverse remodeling prevention of hibernation
No full textA complex interrelationship exists among chronic ischemic left ventricular dysfunction, persistence of myocardial viability and possibility to limit progression of chronic heart failure. Cardiac remodeling is influenced by several factors still under investigation. Hibernation is basically an adaptive mechanism
to chronically abnormal coronary blood flow, characterized by metabolic and structural alterations of the cardiac tissue, that are fully recovered upon revascularization. The estimate of the prevalence of myocardial viability in patients with chronic ischemic left ventricular dysfunction is crucial and different figures can be obtained by applying different diagnostic techniques and
analyzing different cohorts of patients. In patients with chronic heart failure and substantial areas of myocardial ischemia and viability, revascularization is likely to prolong survival. The amount of viable myocardium needed to be clinically relevant remains to be established: only randomized prospective studies, focusing on both functional improvement and prognosis, will give an evidence-based conclusion. An aggressive and thoughtful surgical approach to patients with ischemic heart failure can yield satisfying long-term results, with survival rates superior to medical management alone, and can constitute a true and valid alternative to heart transplantation
TNF alpha in patients with congestive heart failure
No full textIt is now generally accepted that chronically extensive stimulation
of the cytokine system – and of TNF in particular – is detrimental to the heart and to peripheral tissue and that such stimulation may contribute to the pathogenesis of congestive heart failure of various causes. During the past decade, basic and clinical research has provided growing evidence for the role of systemic and local inflammatory responses that, however, have so far failed to translate into new treatments for patients. The present paper represents an attempt to critically review the general concepts that lie behind the dichotomy existing between an impressive bulk of biologic research showing the role of TNF as a pathogen in congestive heart failure and the difficulties in translating this evidence into patients’ treatment
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
Effects of amipamil on myocardial sarcolemmal and mitochondrial calcium transport, comparison with verapamil and nifedipine.
No full textEffect of angiotensin converting enzyme inhibition with quinaprilat on the ischaemic and reperfused myocardium
No full textWe assessed whether the local inhibition of myocardial converting enzyme by quinaprilat and captopril reduces the functional and metabolic damage caused by ischaemia and reperfusion. Quinaprilat and captopril were either subcutaneously injected (0.3 mg/kg once daily for 5-6 days) in the rabbit before isolation of the heart or delivered to the isolated hearts in the perfusate (10-6 M) 60 min before ischaemia. Cardiac protection was evaluated in terms of left ventricular pressure recovery during reperfusion, creatine phosphokinase (CPK) release, mitochondrial function, ATP and CP tissue contents, calcium homeostasis and the occurrence of oxidative stress, established by measuring content and release of reduced and oxidized glutathione. Both drugs exerted cardioprotection. Optimal myocardial preservation is achieved when quinaprilat is prophylactically administered to the rabbit. Recovery of developed pressure on reperfusion improved from 11.3 ± 2.7 (S.E.) to 25.4 ± 5.4 mmHg, P < 0.01 and the release of CPK was reduced from 665.8 ± 101.4 to 231.8 ± 81.4 mU/min/g wet wt, P < 0.01. Peak of noradrenaline release was also attenuated, from 5.253 ng/min/g wet wt to 1.764 ng/min/g wet wt. The accumulation of tissue and mitochondrial calcium was reduced from 52.3 ± 7.5 and 44.1 ± 5.6 to 20.5 ± 3.2 and 27.3 ± 4.6 nmol/kg dry wt, respectively, P < 0.01. This resulted in significant (P < 0.01) improvement of left ventricular diastolic dysfunction during ischaemia and reperfusion and in a preservation of all indices of mitochondrial function, allowing a higher recovery of ATP and CP after reperfusion (from 4.1 ± 0.5 and 5.2 ± 0.5 to 11.1 ± 1.1 and 24.8 ± 1.0 μmol/g dry wt, respectively, P < 0.01). Reperfusion-induced myocardial accumulation and release of oxidized glutathione were reduced from 0.301 ± 0.056 and 0.318 ± 0.083 to 0.138 ± 0.025 nmol/mg protein and 0.076 ± 0.012 nmol/min/g wet wt, respectively, P < 0.01. Similar results were obtained when quinaprilat was administered to the isolated heart. These data suggest that the cardioprotective effect of quinaprilat is independent from haemodynamic changes or direct reduction of toxicity due to oxygen free-radicals but it is likely to be related to a reduction in the release of noradrenaline, maintainance of high energy phosphates and membrane integrity
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