1,721,033 research outputs found
Methylene blue: potential use of an antique molecule in vasoplegic syndrome during cardiac surgery.
No full textVasoplegic syndrome is a common complication of cardiopulmonary bypass, appearing with an incidence ranging between 5 and 25%. It is characterized by significant hypotension, high or normal cardiac output and low systemic vascular resistance. This syndrome is hypothesized to be caused by the inflammation-mediated dysregulation of endothelial homeostasis and subsequent endothelial dysfunction. In vasoplegic syndrome, the inhibition of the nitric oxide/cyclic guanosine monophosphate pathway with concomitant administration with traditional ionotropes may represent a promising therapeutic option. Methylene blue, an inhibitor of nitric oxide synthase and guanylate cyclase, may contribute to the improvement of refractory hypotension associated with endothelial dysfunction in vasoplegia. In this article, we will update evidence on the potential therapeutic use of methylene blue in vasoplegic syndrome
Role of matrix metalloproteinases in animal models of ischemic stroke
No full textMatrix metalloproteinases (MMP) comprise a family of at least 25 zinc-dependent endopeptidases that play a pivotal role in the physiopathology of the mammalian central nervous system. In the first phases after stroke, the dysregulation of MMPs has been described to increase acute neurovascular disruption and cerebral injury. In particular, MMP-mediated alterations lead to blood-brain barrier (BBB) leakage, cerebral edema, hemorrhage, leukocyte infiltration and progressive inflammatory reactions underlying brain tissue loss. In addition, MMPs have been also shown to play critical activities during the repair phases of cerebral ischemia, particularly during angiogenesis and reestablishment of cerebral blood flow. The aim of this narrative review is to elucidate the mechanisms by which MMPs may provide detrimental and/or beneficial effects during the post-stroke injury and repair phases in animal models
Matrix metalloproteinase-9: a deleterious link between hepatic ischemia-reperfusion and colorectal cancer
No full textDespite the advent of improved surgical techniques and the development of cytotoxic chemotherapeutic agents useful for the treatment of colorectal cancer, the primary clinical challenge remains that of preventing and combating metastatic spread. Surgical resection is the best treatment for colorectal metastases isolated to the liver. However, in rodent models, the hepatic ischemia-reperfusion (I/R) applied during the surgery accelerates the outgrowth of implanted tumors. Among the adverse effects of I/R on cellular function, several studies have demonstrated an over expression of the matrix metalloproteinase-9 (MMP-9) in the ischemic liver. Since several studies showed high local levels of expression and activity of this proteolytic enzyme in the primary colorectal adenocarcinoma, the role of MMP-9 might be considered as a potential common mediator, favoring both growth of local tumor and the dissemination of colorectal carcinoma metastases
Role of Matrix Metalloproteinase-8 in Atherosclerosis
No full textPlaque rupture is the main cause of acute myocardial infarction and stroke. Atherosclerotic plaques have been described to be vulnerable and more prone to rupture when they are characterized by thin, highly inflamed, and collagen-poor fibrous caps and contain elevated levels of proteases, including metalloproteinases (MMPs). Initiation of collagen breakdown in plaques requires interstitial collagenases, a MMP subfamily consisting of MMP-1, MMP-8, and MMP-13. Previous reports demonstrated that MMP-1 and MMP-13 might be overexpressed in both human and experimental atherosclerosis. Since neutrophils have been only recently reported in atherosclerotic plaques, the role of MMP-8 (formerly known as “neutrophil collagenase”) was only marginally evaluated. In this paper, we will update and comment on evidence of the most relevant regulatory pathways and activities mediated by MMP-8 in atherogenesis
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
Alpha-fetoprotein: a controversial prognostic biomarker for small hepatocellular carcinoma
No full textThe assessment of the prognosis in patients with early hepatocellular carcinoma represents a hot-topic issue that requires further improvements and clarifications. The life expectancy of the patients has been shown to depend on several clinical and histological parameters (such as patient's general conditions, macroscopic tumor morphology and histopathology). Recently, the prognostic role of some biomarkers [i.e., alpha-fetoprotein (AFP)] has been also investigated with controversial findings mainly on the assessment of patient survival. The study by Giannini et al failed to show a prognostic value of AFP on survival of patients with well-compensated cirrhosis and small hepatocellular carcinoma. Since the study presents some limitations, a larger clinical trial is needed to clarify the potential prognostic role of serum AFP levels in these patients
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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