1,720,963 research outputs found
Release of cardiac troponin I in antegrade crystalloid versus cold blood cardioplegia
No full textObjective: The purpose of this study was to assess the efficacy of myocardial protection, comparing antegrade crystalloid cardioplegia with cold blood cardioplegia, in patients with preserved left ventricular function who were undergoing elective first coronary artery bypass grafting, Release of cardiac troponin I was used as a marker for the effectiveness of myocardial protection, Methods: A consecutive series of 62 patients were randomly assigned to receive crystalloid or blood cardioplegia, Cardiac troponin I concentrations were determined in venous blood samples before the operation, immediately after unclamping, at 6, 9, 12, and 24 hours, and daily thereafter for 5 days, Results: Rising levels of troponin I were found in all patients. The time course and peak release were similar in the crystalloid cardioplegia and the blood cardioplegia groups. No patients in either group had electrocardiographic evidence of perioperative myocardial infarction, Cardiac troponin I was able to detect small areas of myocardial damage, not revealed by electrocardiography or creatine kinase MB release, Aprotinin administration was associated with lower cardiac troponin I release in both groups, Cardiac troponin I was lower in patients whose conditions did not require electrical defibrillation after aortic unclanlping, irrespective of cardioplegia type. The presence of a main stem lesion was associated with higher cardiac troponin I release only in the crystalloid cardioplegia group. Conclusions: Antegrade cold blood cardioplegia is equally effective as antegrade crystalloid cardioplegia in a randomized group of patients with preserved left ventricular function who were undergoing elective first coronary artery bypass grafting, Aprotinin administration resulted in lower cardiac troponin I release, whereas electrical defibrillation was related to a higher release irrespective of cardioplegia type, The presence of a main stem lesion resulted in higher cardiac troponin I release in the crystalloid cardioplegia group
Release of cardiac troponin I in antegrade crystalloid versus cold blood cardioplegia
No full textObjective: The purpose of this study was to assess the efficacy of myocardial protection, comparing antegrade crystalloid cardioplegia with cold blood cardioplegia, in patients with preserved left ventricular function who were undergoing elective first coronary artery bypass grafting, Release of cardiac troponin I was used as a marker for the effectiveness of myocardial protection, Methods: A consecutive series of 62 patients were randomly assigned to receive crystalloid or blood cardioplegia, Cardiac troponin I concentrations were determined in venous blood samples before the operation, immediately after unclamping, at 6, 9, 12, and 24 hours, and daily thereafter for 5 days, Results: Rising levels of troponin I were found in all patients. The time course and peak release were similar in the crystalloid cardioplegia and the blood cardioplegia groups. No patients in either group had electrocardiographic evidence of perioperative myocardial infarction, Cardiac troponin I was able to detect small areas of myocardial damage, not revealed by electrocardiography or creatine kinase MB release, Aprotinin administration was associated with lower cardiac troponin I release in both groups, Cardiac troponin I was lower in patients whose conditions did not require electrical defibrillation after aortic unclanlping, irrespective of cardioplegia type. The presence of a main stem lesion was associated with higher cardiac troponin I release only in the crystalloid cardioplegia group. Conclusions: Antegrade cold blood cardioplegia is equally effective as antegrade crystalloid cardioplegia in a randomized group of patients with preserved left ventricular function who were undergoing elective first coronary artery bypass grafting, Aprotinin administration resulted in lower cardiac troponin I release, whereas electrical defibrillation was related to a higher release irrespective of cardioplegia type, The presence of a main stem lesion resulted in higher cardiac troponin I release in the crystalloid cardioplegia group
A possible role of the tubuloglomerular feedback mechanism in ischemic or hypoxic injury studied in the isolated rabbit kidney perfused with autologous blood
No full textSince functional and morphological damage after ischemic or hypoxic injury in the isolated perfused rabbit kidney is unknown, the present study starts to examine kidney function and morphology after ischemia and hypoxia. Subsequently, the study focuses on the question whether TGF is involved in the deterioration of the kidney function after exposure to hypoxia. Therefore it was aimed to inhibit TGF at three different levels: 1. Inhibition of the sensor of the TGF. This might be achieved with furosemide via inhibition of the transport at the macula densa cells, the initial step of the TGF. 2. A rightward resetting of the TGF via induction of a modulator, nitric oxide, of the TGF mechanism. This is aimed via addition of L-arginine. 3. Inhibition of adenosine, the suggested mediator of the TGF mechanism. This is pursued via a selective inhibition of the A1 and the A2 adenosine receptor. According to the introduction, adenosine and NO might also be involved in the protection against ischemia, elicited by IPC. Therefore the possible protective effects of IPC and AP against ischemia are examined in the isolated perfused kidney. It would be relevant for the understanding of the pathophysiological mechanism if the question could be answered whether IPC alters the sensitivity of the TGF. Model As discussed previously, systemic influences may affect the pathophysiology of acute renal failure. In order to study the intrinsic functional changes of the kidney itself, the isolated kidney preparation is used to exclude systemic effects. Since perfusion in the presence of erythrocyte prevents injury to the mTAL and reduces the FE Na+ , the isolated rabbit kidney perfused with autologous blood is used as a model to study the pathophysiology of acute renal failure in the present study. This model was functionally characterized in control conditions and it was shown that this preparation did not deteriorate before two hours of blood perfusion
A possible role of the tubuloglomerular feedback mechanism in ischemic or hypoxic injury studied in the isolated rabbit kidney perfused with autologous blood
No full textSince functional and morphological damage after ischemic or hypoxic injury in the isolated perfused rabbit kidney is unknown, the present study starts to examine kidney function and morphology after ischemia and hypoxia. Subsequently, the study focuses on the question whether TGF is involved in the deterioration of the kidney function after exposure to hypoxia. Therefore it was aimed to inhibit TGF at three different levels: 1. Inhibition of the sensor of the TGF. This might be achieved with furosemide via inhibition of the transport at the macula densa cells, the initial step of the TGF. 2. A rightward resetting of the TGF via induction of a modulator, nitric oxide, of the TGF mechanism. This is aimed via addition of L-arginine. 3. Inhibition of adenosine, the suggested mediator of the TGF mechanism. This is pursued via a selective inhibition of the A1 and the A2 adenosine receptor. According to the introduction, adenosine and NO might also be involved in the protection against ischemia, elicited by IPC. Therefore the possible protective effects of IPC and AP against ischemia are examined in the isolated perfused kidney. It would be relevant for the understanding of the pathophysiological mechanism if the question could be answered whether IPC alters the sensitivity of the TGF. Model As discussed previously, systemic influences may affect the pathophysiology of acute renal failure. In order to study the intrinsic functional changes of the kidney itself, the isolated kidney preparation is used to exclude systemic effects. Since perfusion in the presence of erythrocyte prevents injury to the mTAL and reduces the FE Na+ , the isolated rabbit kidney perfused with autologous blood is used as a model to study the pathophysiology of acute renal failure in the present study. This model was functionally characterized in control conditions and it was shown that this preparation did not deteriorate before two hours of blood perfusion
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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