1,721,072 research outputs found
EVALUATION OF L-ARGININE/NITRIC OXIDE METABOLIC PATHWAY IN ERYTHROCYTES IN RELATION WITH OXIDATIVE STRESS: FOCUS ON DIFFERENT CARDIOVASCULAR DISEASES
Full text linkBackground: A decreased nitric oxide (NO) bioavailability and an increased oxidative stress play a pivotal role in different cardiovascular pathologies. Recent studies have shown that red blood cells (RBCs) participate in NO formation in the bloodstream.
Aim: The aim of this study was to assess the L-arginine (Arg)/NO pathway and the oxidative stress status in RBCs and in plasma of patients with microvascular angina (MVA), investigating similarities and differences with respect to coronary artery disease (CAD) patients or healthy controls (Ctrl).
Materials and Methods: Analytes involved in Arg/NO pathway and the ratio between the oxidized and the reduced forms of glutathione, as index of oxidative stress, were measured by liquid-chromatography tandem mass spectrometry (LC-MS/MS). The arginase and the NO synthase (NOS) expression were assessed by immunofluorescence staining. NOS activity was evaluated by ex-vivo experiments through the conversion of L-[15N2]arginine to L-[15N]citrulline.
Results: Both MVA and CAD patients showed alterations in the ability of RBCs to produce NO, based on an increase of NO synthesis inhibitors, parallel to that found in plasma, a reduction of NOS expression and activity and an increased arginase expression. When summary scores of NO synthesis and of oxidative stress were computed, both patient groups were associated with a positive oxidative score and a negative NO score, with the CAD group located in a more extreme position with respect to Ctrl.
Conclusions: This finding points out to an impairment of the capacity of RBCs to produce NO in pathological conditions characterized by alteration at the microvascular bed with/without no significant coronary stenosis
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
The red blood cell : a new key player in cardiovascular homoeostasis? Focus on the nitric oxide pathway
No full textRBCs (red blood cells) have a fundamental role in the regulation of vascular homoeostasis thanks to the ability of these cells to carry O 2 (oxygen) between respiratory surfaces and metabolizing tissues and to release vasodilator compounds, such as ATP and NO (nitric oxide), in response to tissue oxygenation. More recently it has been shown that RBCs are also able to produce NO endogenously as they express a functional NOS (nitric oxide synthase), similar to the endothelial isoform. In addition, RBCs carry important enzymes and molecules involved in l-arginine metabolism, such as arginase, NO synthesis inhibitors and the cationic amino acid transporters. Altogether these findings strongly support the role of these cells as producers, vehicles and scavengers of NO, therefore affecting several physiological processes such as blood rheology and cell adhesion. Consequently, the importance of alterations in the l-arginine/NO metabolic pathway induced by specific conditions, e.g. oxidative stress, in different pathological settings have been investigated. In the present review we discuss the role of RBCs in vascular homoeostasis, focusing our attention on the importance of the NO pathway alterations in cardiovascular diseases and their relationship to major risk factors
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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