1,720,972 research outputs found
Large emboli on their way through the heart - First live demonstration of large paradoxical embolisms through a patent foramen ovale
No full textWe report a case of large paradoxical embolisms through a patent foramen ovate in a patient with acquired heparin-induced thrombocytopenia type II (HIT). One large ventricular thrombus embolizing through the aortic valve was documented on videotape for the first time while performing transesophageal echocardiography. A 56-year-old man was admitted with acute respiratory failure initially believed to have an exacerbated chronic obstructive pulmonary disease. Arterial oxygen saturation was only 33%. He received antibiotic and anti-obstructive treatments and was mechanically ventilated for 7 days. Few hours after extubation, he developed recurrent severe dyspnea accompanied by acute pain and pulselessness in his left leg. Transthoracic echocardiography revealed an enlarged right ventricle and suggested the presence of free-floating thrombi both in the right and in the left-heart cavities. During transesophageal echocardiography, a large serpentine left-heart thrombus embolized through the aortic valve and disappeared. The patient developed ventricular fibrillation and underwent successful cardiopulmonary resuscitation including emergency thrombolysis with alteplase. Four hours later, the surgeon retrieved a 20-cm tong thrombus from the left femoral, artery. (C) 2006 The European Society of Cardiology. Published by Elsevier Ltd. All rights reserved
Prevention of TNF alpha-associated myocardial dysfunction resulting from cardiopulmonary bypass and cardioplegic arrest by glucocorticoid treatment
No full textObjective: Cardiac surgery on cardiopulmonary bypass (CPB) results in progressive myocardial dysfunction, despite unimpaired coronary blood flow, and is associated with increased myocardial tumor necrosis factor-alpha (TNF alpha) expression. We investigated whether anti-inflammatory treatment prevents increased TNF alpha expression and myocardial dysfunction after CPB. Methods and results: Baseline systemic hemodynamics, myocardial contractile function, aortic and coronary blood flow were measured in anesthetized pigs. Then, placebo (PLA; saline; n = 7) or methylprednisolone (MP; 30 mg/kg; n = 6) was infused intravenously and CPB was instituted. Global ischemia was induced for 10 min by aortic cross-clamping, followed by 1 h of cardioplegic cardiac arrest. After declamping and reperfusion, CPB was terminated after a total of 3 h. Measurements were repeated at 15 min, 4 h, and 8 h following termination of CPB. Systemic TNF alpha-plasma concentrations and left ventricular TNF alpha expression were analyzed. With unchanged coronary blood flow in both groups, a progressive toss of myocardial contractile function to 38 +/- 2% of baseline (p < 0.01) and cardiac index to 48 +/- 6% of baseline (p < 0.01) at 8 h after CPB in PLA was attenuated in MP (myocardial function: 72 +/- 3%, p < 0.01 vs PLA; cardiac index: 78 +/- 6%, p < 0.05 vs PLA). Systemic TNFa was increased at 8 h in PLA compared to MP (243 +/- 34 vs 90 +/- 34 pg/ml, p < 0.05). Myocardial TNF alpha was increased at 8 h after CPB compared to baseline and MP (p < 0.05). Myocardial TNF alpha immunostaining was more pronounced in PLA than in MP (p < 0.05), with TNF alpha-mRNA localization predominantly to cardiomyocytes. Conclusions: Methylprednisolone attenuates both systemic and myocardial TNF alpha increases and progressive myocardial dysfunction induced by cardiac surgery, suggesting a key rote for TNF alpha. (c) 2006 Elsevier B.V. All rights reserved
alpha(1)-adrenergic stress induces downregulation of Na+/Ca2+ exchanger in myocardial preparations from rabbits at physiological preload
No full textalpha 1-adrenergic stimulation and mechanical load are considered crucial for the expression of sarcolemmal Na+/Ca2+ exchanger (NCX1). However, the interaction between these processes is unknown. We investigated electrically stimulated (1 Hz, 1.75 mmol/L Ca2+) rabbit ventricular trabeculae at physiological preload under stimulation by the selective alpha(1)-agonist phenylephrine (PE, 10 mu mol/L). Using quantitative real-time PCR, downregulation of mRNA to 76.5% (p<0.05) was found, while B-type natriuretic peptide (BNP) was increased to 569.5% (p<0.05) compared to control. These changes were abolished in the presence of both the alpha(1)-blocker prazosin (13 mu mol/L) and the PKC inhibitor GF109203X (1 mu mol/L). Furthermore, no changes in NCX mRNA levels under the influence of PE were found in unstretched trabeculae or in unstretched isolated rabbit myocytes (24 h), while BNP was increased in both preparations. In addition, since the alpha(1)-adrenergic effect could be Ca2+-dependent we tested increased extracellular Ca2+ (3.0 mmol/L) in stretched trabeculae and found downregulation of NCX1 to 75.2% (p<0.05). alpha(1)-stimulation decreases NCX I mRNA in rabbit myocardium via PKC. This is critically load-dependent and may be mediated by changes in [Ca2+]. In hypertrophy and heart failure, distinct phenotypes with respect to NCX1 expression may result from the interaction between mechanical load and alpha(1)-adrenergic stimulation. (c) 2006 European Society of Cardiology. Published by Elsevier B.V. All rights reserved
BNP controls early load-dependent regulation of SERCA through calcineurin
No full textHeart failure is characterised by reduced expression of sarcoplasmic reticulum calcium-ATPase (SERCA) and increased expression of B-type natriuretic peptide (BNP). The present study was performed to investigate causality of this inverse relationship under in vivo conditions in the transversal aortic constriction mouse model (TAC). Left ventricular SERCA-mRNA expression was significantly upregulated in TAC by 32% after 6 h, but not different from sham after 24 h. Serum proANP and BNP levels were increased in TAC after 24 h (BNP +274%, p < 0.01; proANP +60%, p < 0.05), but only proANP levels were increased after 6 h (+182%, p < 0.01). cGMP levels were only increased 24 h after TAC (+307%, p < 0.01), but not 6 h after TAC. BNP infusion inhibited the increase in SERCA expression 6 h after TAC. In BNP-receptor-knockout animals (GC-A), the expression of SERCA was still significantly increased 24 h after TAC at the mRNA level by 35% (p < 0.05), as well as at the protein level by 25% (p < 0.05). MCIP expression as an indicator of calcineurin activity was regulated in parallel to SERCA after 6 and 24 h. MCIP-mRNA was increased by 333% 6 h after TAC, but not significantly different from sham after 24 h. In the GC-A-KO mice, MCIP-mRNA was significantly increased in TAC compared to WT after 24 h. In mice with BNP infusion, MCIP was significantly lower 6 h after TAC compared to control animals. In conclusion, mechanical load leads to an upregulation of SERCA expression. This is followed by upregulation of natriuretic peptides with subsequent suppression of SERCA upregulation. Elevated natriuretic peptides may suppress SERCA expression by inhibition of calcineurin activity via activation of GC-A
High Precision Quantitative Proteomics Using iTRAQ on an LTQ Orbitrap: A New Mass Spectrometric Method Combining the Benefits of All
No full textThe development of quantitative techniques in mass spectrometry has generated the ability to systematically monitor protein expression. Isobaric tags for relative and absolute quantification (iTRAQ) have become a widely used tool for the quantification of proteins. However, application of iTRAQ methodology using ion traps and hybrid mass spectrometers containing an ion trap such as the LTQ-Orbitrap was not possible until the development of pulsed Q dissociation (PQD) and higher energy C-trap dissociation (HCD). Both methods allow iTRAQ-based quantification on an LTQ-Orbitrap but are less suited for protein identification at a proteomic scale than the commonly used collisional induced dissociation (CID) fragmentation. We developed an analytical strategy combining the advantages of CID and HCD, allowing sensitive and accurate protein identification and quantitation at the same time. In a direct comparison, the novel method outperformed PQD and HCD regarding its limit of detection, the number of identified peptides and the analytical precision of quantitation. The new method was applied to study changes in protein expression in mouse hearts upon transverse aortic constriction, a model for cardiac stress
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
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