1,720,984 research outputs found
Overview of ventilator-induced lung injury mechanisms
No full textPURPOSE OF REVIEW: Mechanical ventilation is the main supportive therapy for patients with acute respiratory distress syndrome. As with any therapy, mechanical ventilation has side effects and may induce lung injury. This review will focus on stretch-dependent activation of alveolar epithelial and endothelial cells and polymorphonuclear leukocytes, and apoptosis/necrosis balance. RECENT FINDINGS: The past year has seen important research in the area of mechanotransduction and lung native immunity, suggesting further mechanisms of lung inflammation and injury in ventilator-induced lung injury. Research in the past year has also stressed the importance of inflammatory response by alveolar cells and role of polymorphonuclear leukocytes in stretch-induced lung injury and has suggested a role for apoptosis in the maintenance of the alveolar epithelium. SUMMARY: The proportion of patients receiving protective ventilatory strategies remains modest. If efforts to minimize the iatrogenic consequences of mechanical ventilation are to succeed, there must be a greater understanding of the signal transduction mechanisms and the development of potential pharmacologic targets to modulate the molecular and cellular effects of lung stretch
Control of autocrine and paracrine myocardial signals: an emerging therapeutic strategy in heart failure
No full textA growing body of evidence supports the hypothesis that autocrine and paracrine mechanisms, mediated by factors released by the resident cardiac cells, could play an essential role in the reparative process of the failing heart. Such signals may influence the function of cardiac stem cells via several mechanisms, among which the most extensively studied are cardiomyocyte survival and angiogenesis. Moreover, besides promoting cytoprotection and angiogenesis, paracrine factors released by resident cardiac cells may alter cardiac metabolism and extracellular matrix turnover, resulting in more favorable post-injury remodeling. It is reasonable to believe that critical intracellular signals are activated and modulated in a temporal and spatial manner exerting different effects, overall depending on the microenvironment changes present in the failing myocardium. The recent demonstration that chemically, mechanically or genetically activated cardiac cells may release peptides to protect tissue against ischemic injury provides a potential route to achieve the delivery of specific proteins produced by these cells for innovative pharmacological regenerative therapy of the heart. It is important to keep in mind that therapies currently used to treat heart failure (HF) and leading to improvement of cardiac function fail to induce tissue repair/regeneration. As a matter of facts, if specific autocrine/paracrine cell-derived factors that improve cardiac function will be identified, pharmacological-based therapy might be more easily translated into clinical benefits than cell-based therapy. This review will focus on the recent development of potential pharmacologic targets to promote and drive at molecular level the cardiac repair/regeneration in HF
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
Early detection of acute lung injury uncoupled to hypoxemia in pigs using ultrasound lung comets
No full textObjective: Oleic acid-induced lung injury is an established experimental model of acute lung injury in pigs and is considered to reproduce the early exudative phase of acute respiratory dis- tress syndrome. Ultrasound lung comets are an echographic sign of extravascular lung water, originating from thickened interlob- ular septa. The objective of this study was to evaluate the timing and relationship between the number of ultrasound lung comets, the PaO2/FIO2 ratio, and the static respiratory compliance in an experimental model of oleic acid-induced lung injury in pigs. Design: Laboratory experiment. Setting: Research institute. Subjects: Ten anesthetized pigs. Interventions: Acute lung injury was induced by injection of oleic acid (0.1 mL/kg, intravenously). Ultrasound lung comets, PaO2/FIO2, and static respiratory compliance were measured at baseline and at 15, 30, 60, and 90 mins after the injection of oleic acid. We evaluated ultrasound lung comets by transthoracic echography (7.5-MHz vascular probe), scanning on right and left hemithoraxes at 12 predefined scanning sites. Measurements and Main Results: Acute lung injury/acute re- spiratory distress syndrome was present in all pigs at 90 mins. The number of ultrasound lung comets increased over time and was consistently earlier than the decrease in PaO2/FIO2. At 15 mins, ultrasound lung comets were markedly increased, but no significant changes in PaO2/FIO2 were observed. Accordingly, static respiratory compliance was dramatically reduced at 15 mins compared with baseline (17.04 1.82 vs. 34.84 2.62 mL/cm H2O, p < .05). Conclusions: Ultrasound lung comets, assessed by transtho- racic echography, detected extravascular lung water accumu- lation very early in the course of the oleic acid-lung injury in pigs, in the presence of a normal PaO2/FIO2. These results suggest that ultrasound lung comets could be a very early, noninvasive, and simple method to detect and quantify pulmo- nary edema in acute lung injury
Ferritin as a reporter gene to track stem cells by cardiac magnetic resonance imaging, in vivo
No full textNot availabl
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
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