1,720,990 research outputs found
HYPOXIC SIGNALS IN THE ISCHEMIC MYOCARDIUM: ROLE OF GALECTIN-1 AND GALECTIN-3
Full text linkMyocardial infarction is the most serious manifestation of coronary artery disease and the cause of significant levels of mortality and morbidity worldwide. Galectin-1 (GAL-1) and Galectin-3 (GAL-3) are beta galactoside binding lectins with diverse functions. Hypoxia inducible factor-1 alpha (HIF-1α) is a transcription factor mediating early and late responses to myocardial ischemia. We aim to study the direct effects of ischemia on GAL-1, GAL-3 and HIF-1α in the heart. Male C57B6/J and GAL-3 knockout mice were used for our two disease models. In the Myocardial infarction (MI) model, the left anterior descending artery of the heart is permanently ligated to create ischemia in the anterior myocardium. In the Ischemia reperfusion model (IR), the artery is temporarily ligated for a specific period of time and then reperfusion is established. Heart samples were processed for immunohistochemical and immunofluorescent labeling, western blotting, Enzyme linked immunosorbent assay and quantitative real time PCR. Inflammatory, Apoptotic and Oxidative stress markers were also studied. We show for the first time that GAL-1, GAL-3 and HIF-1α levels in the left ventricle are raised in early ischemic period in conjunction with a predominant antiapoptotic activity in the heart. Our identification of the pattern of expression of GAL-1, GAL-3 and HIF-1α in the heart during the first 24 hours following acute MI has helped in understanding early molecular changes in this event and may provide methods to overcome serious complications. Our work further showed that GAL-3 acted as a regulator of proinflammatory and antiapoptotic mechanisms in the myocardium after myocardial infarction that will shape the future course of the disease. GAL-3 was also shown to interfere with vii redox pathways controlling cell survival and death and plays a protective role in the pathogenesis of ischemia reperfusion injury in the heart. Our work has contributed in understanding the local microenvironment in which GAL-3 works in the heart after ischemia/infarction or ischemia-reperfusion and has opened a new window in understanding the exact role of GAL-3 in the heart
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
Introduction to research ethics and integrity
No full textEthics deals with moral principles. The ethical principles of autonomy, beneficence, non-maleficence and justice applies to biomedical research as much as it applies to other human activities. This chapter gives an overview of the ethics of planning, conducting, and reporting of research. It discusses the basic principles of collection, use and interpretation of research data. It touches upon areas pertaining to the protection of research subjects and ethical principles governing the use of human and animal in research. The concept of research misconduct and importance of responsible conduct in research is also discussed. Education in research ethics is essential for all scientists and researchers as it equips them to assess, interpret and apply ethical principles in different situations
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
Galectin-3 is expressed in the myocardium very early post-myocardial infarction
No full textBackground: Galectin-3 (GAL-3) plays a regulatory role in several diverse biological processes and disease states. It is associated with heart failure and increased risk of death in a number of studies. We aim to study the direct effects of ischemia on GAL-3 levels in the heart very early in the course of events following myocardial infarction (MI).Methods: Male C57B6/J mice were used for permanently ligating the left anterior descending artery of the heart to create ischemia/infarction in the anterior wall of left ventricle (LV). Heart samples were processed for immunohistochemical and immunofluorescent labeling, enzyme-linked immunosorbent assay, and quantitative reverse transcriptase polymerase chain reaction to identify GAL-3 levels in the heart during the first 24 h following MI.Results: GAL-3 mRNA was significantly increased at 60min (P=.032), 4 h (P=.012), and 24 h (P=.00) post-MI groups in the infarcted LV as compared to sham. Thirty minutes post-MI GAL-3 mRNA is higher than the sham and almost reaching statistical significance (P=.056). GAL-3 protein was significantly increased in the LV at 30 min (P=.021), 60 min (P=.029), 4 h (P=.015), and 24 h (P=.01) post-MI compared to corresponding sham-operated mice. Plasma GAL-3 levels are also significantly raised at 24-h post-MI. GAL-3 is colocalized with cardiomyocytes and endothelial cells in the ischemic area of the LV. GAL-3 is also colocalized with hypoxia-inducible factor-1 alpha (HIF-1α).Conclusions: We show for the first time that GAL-3 is increased at both transcriptional and translational levels in the LV in early ischemic period, which can possibly be a part of the prosurvival gene expression profile transcribed by HIF-1α. This is significant because it can help in understanding the mechanism of very early response of the myocardium following acute infarction and help devise ways to save the viable tissue before permanent damage sets in
Acute myocardial infarction and myocardial ischemia-reperfusion injury: A comparison
Full text linkMyocardial infarction (MI) denotes the death of cardiac myocytes due to extended ischemia. Myocardial reperfusion is the restoration of coronary blood flow after a period of coronary occlusion. Reperfusion has the potential to salvage ischemic myocardium but paradoxically can cause injury, a phenomenon called as \u27reperfusion injury\u27 (IR). Standard histologic, immunohistochemical and Elisa techniques were used to study the histopathologic, oxidative, apoptotic and inflammatory changes in MI and IR. The IL-6 levels in the LV of the MI group were significantly raised as compared to the IR group (P=0.0008). Plasma IL-6 was also significantly increased in the MI group as compared to the IR group (P=0.031). MI model was also associated with increase in the neutrophil polymorphs number in the infarction related myocardium as compared to the re-perfused myocardium. A significant increase in troponin I level in the MI group as compared to the IR group is also seen (P=0.0001). Our IR model showed enhanced pro-apoptotic mediators like cleaved caspase-3 (P=0.005) and cytochrome c in the myocardium as compared to the MI model. In conclusion, myocardial damage in MI is mainly due to ischemic necrosis and inflammatory mechanisms while apoptosis is the main mechanism of cell death in IR in addition to limited ischemic necrosis
Molecular switch model for cardiomyocyte proliferation
Full text linkThis review deals with the human adult cardiomyocyte proliferation as a potential source for heart repair after injury. The mechanism to regain the proliferative capacity of adult cardiomyocytes is a challenge. However, recent studies are promising in showing that the \u27locked\u27 cell cycle of adult cardiomyocytes could be released through modulation of cell cycle checkpoints. In support of this are the signaling pathways of Notch, Hippo, Wnt, Akt and Jak/Stat that facilitate or inhibit the transition at cell cycle checkpoints. Cyclins and cyclin dependant kinases (CDKs) facilitate this transition which in turn is regulated by inhibitory action of pocket protein e.g. p21, p27 and p57. Transcription factors e.g. E2F, GATA4, TBx20 up regulate Cyclin A, A2, D, E, and CDK4 as promoters of cell cycle and Meis-1 and HIF-1 alpha down regulate cyclin D and E to inhibit the cell cycle. Paracrine factors like Neuregulin-1, IGF-1 and Oncostatin M and Extracellular Matrix proteins like Agrin have been involved in cardiomyocyte proliferation and dedifferentiation processes. A molecular switch model is proposed that transforms the post mitotic cell into an actively dividing cell. This model shows how the cell cycle is regulated through on- and off switch mechanisms through interaction of transcription factors and signaling pathways with proteins of the cell cycle checkpoints. Signals triggered by injury may activate the right combination of the various pathways that can \u27switch on\u27 the proliferation signals leading to myocardial regeneration
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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