1,720,959 research outputs found
Myocardial histology and outcome after cardiopulmonary bypass of neonatal piglets
Full text linkBackground: Early after neonatal cardiac surgery hemodynamic dysfunction may be evident. However, still is not clear if dysfunction and outcome is related to visible myocardial alterations. The aim of the present study was the histological analysis of myocardial tissue of neonatal piglets after cardiopulmonary bypass (CPB) and cardioplegic arrest. Methods: Neonatal piglets (younger than 7 days) were connected to CPB for 180 min, including 90 min of cardioplegic heart arrest at 32 degrees C. After termination of CPB the piglets were observed up to 6 h. During this observational period animals did not receive any inotropic support. Some piglets died within this period and formed the non-survivors group (CPB-NS group) and the remaining animals formed the CPB-6 h group. Myocardial biopsies (stained with H&E) were scored from 0 to 3 regarding histological alterations. Then, the histological data were evaluated and compared to the probes of animals handled comparable to previous piglets but without CPB (non-CPB group; n = 3) and to sibling piglets without specific treatment (control; n = 5). Results: In the first hours after CPB six piglets out of 10 died (median 3.3 h). The animals of CPB-6 h group (n = 4) were sacrificed at the end of experiments (6 h after CPB). Although the myocardial histological score of CPB-6 h group and CPB-NS group were higher than non-CPB group (2.0 +/- 0.8, 1.5 +/- 0.9, and 0.8 +/- 0.3 respectively), these differences were statistically not significant. But compared to control animals (score 0.3 +/- 0.5) the scores of CPB-6 h and CPB-NS groups were significantly higher (p < 0.05). Between the left and the right ventricular tissue there were no significant differences. Conclusions: Myocardial tissue alterations in newborn piglets are related to the surgical trauma and potentiated by cardiopulmonary bypass and ischemia. However, outcome is not related to the degree of tissue alteration.Open-Access Publikationsfonds 201
Postoperative Hemodynamics After Cardiopulmonary Bypass in Survived Newborn Piglets
No full textCardiac function and hemodynamics are frequently decreased during the first hours after heart surgery, resulting in inotropic support for treatment and prevention of further hemodynamic deterioration. The aim of this study was analysis of hemodynamics of neonatal piglets who survived early postoperative course after cardiopulmonary bypass (CPB) and cardioplegic arrest without the use of inotropic drugs. Newborn piglets (younger than 7 days) were placed on mild hypothermic CPB (32 degrees C) for 180 minutes, including 90 minutes of cardioplegic arrest. Hemodynamics were examined after, termination of CPB and none of the animals received any inotropic support. After 6 hours, survived animals were euthanized (CPB group, n = 4). For control, neonatal piglets were examined for the same time interval after surgery without CPB (control group, n = 3). Systolic left-ventricular pressure increased after CPB, mean arterial blood pressure and amplitude of left ventricular wall thickness decreased. Compared with control group, systolic left-ventricular pressure in CPB group was higher (p < 0.05). Present data demonstrated hemodynamic depression after cardiac procedures in survived neonatal animals. Although the effects may not be solely attributed to CPB and myocardial ischemia effects may be potentiate by CPB. ASAIO journal 2009; 55:93-95
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Low‐Output Is Not the Cause of Death of Neonatal Piglets Early After Cardiopulmonary Bypass
No full textThe mortality rate of neonatal piglets after heart surgery is high. Searching for a possible explanation for the death of neonatal piglets early after cardiopulmonary bypass, we analyzed hemodynamic parameters regarding survival and non-survival. Initially, 10 neonatal piglets (younger than 7 days) were connected to cardiopulmonary bypass (CPB). The mean body weight was 2.98+/-0.44 kg. Exposure of the heart was performed through a median sternotomy. After connection to the CPB, the piglets were cooled to 32 degrees C core temperature before the ascending aorta was cross-clamped and the heart arrested (90?min). Thereafter, piglets were re-warmed to 37 degrees C and separated from CPB. During follow-up, the piglets did not receive inotropic support or vasopressors. Piglets who survived at least 2h after termination of CPB were included in the study for further data analysis (n=9). Five piglets died 2.5 to 4.0 h (median: 3.5 h) after CPB; these piglets formed the non-survivors group. Four animals survived the complete follow-up of 6 h after CPB and formed the survivors group. Regarding contractility (dP/dtmax, dP/dtmax/P, and wall thickening) there were not statistically significant differences between the groups. Non-survivors showed prolonged decrease of mean arterial pressure of more than 20% of baseline values, corresponding with a value of below 30?mm?Hg. In conclusion, the death of neonatal piglets early after cardiopulmonary bypass was not determined by low output
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