130,379 research outputs found
Activation of the coagulation system in coronary artery bypass grafting operation: comparison between on-pump and off-pump techniques
No full textObjective: Comparing peri-operative activation of the coagulation and fibrinolytic systems and platelet function in patients receiving CABG operation by means of on pump or off pump techniques. Methods: 32 consecutive patients requiring elective CABG were enrolled in the study and assigned in a randomized fashion to: on pump group or off pump group. Heparin was given at the same dose (300 U/kg) and antifibrinolytic drugs were not administered. Activation of the coagulation system was evaluated by means of Prothrombin Fragment 1.2 (PF-1.2) and Tissue Factor (TF) measurements; fibrinolysis was evaluated measuring Tissutal Plasminogen Activator (TPA), Plasminogen Activator Inhibitor-1 (PAI-1) and D-Dimer (D-D) formation. Platelets function was evaluated by means of the Platelet Function Analyzer (PFA-100®). Blood samples were collected at T0 (during induction of anesthesia), T1 (45 min after heparin administration), T2 (15 min after protamine administration), T3 (3 h after the end of the operation), T4 (postoperative day (POD) 1), T5 (POD4), and T6 (POD6). Results were corrected for haemodilution. Results: No statically significative differences were found in pre, peri and post-operative clinical characteristics between the two groups, except for heparinization time (on pump group 159.6±40.4 min; off pump group 121.6±35.7; P<0.05) and hemoglobin value at POD6 (on pump group 9.3±2.34 g/dl; off pump group 10.9±1.35 g/dl; P<0.05). The coagulation system was activated during cardiopulmonary bypass (CPB) and highest levels of PF-1.2 were measured at T1, T2 and T3 (P<0.05 compared with off pump group); a trend towards increased levels of PF-1.2 was observed in both groups at T4,T5 and T6. TF production was similar in the two groups and no statistically significative differences were found at any sample time. The fibrinolytic system was more activated in the on pump group as demonstrated by TPA levels at T1 (P<0.05), PAI-1 levels at T2 (P<0.05) and D-D levels at T2 and T3 (P<0.05). Not surprisingly, CPB induces platelet dysfunction; PFA-100 bleeding times were significantly elevated in on pump group at T1, T2 and T3 (P<0.05). PFA-100 bleeding postoperative times were not prolonged in both groups despite aspirin administration. Conclusions: Off-pump patients produce less activation of the coagulation system and do not activate fibrinolysis during the operation; their platelet function is preserved during and after the operation. This may explain the reported reduced rate of postoperative bleeding associated with this technique. The absence of fibrinolysis together with functioning platelets and increased thrombin formation postoperatively suggest that off pump patients may experience a pro-thrombotic state
MeSH term explosion and author rank improve expert recommendations
Get PDFInformation overload is an often-cited phenomenon that reduces the productivity, efficiency and efficacy of scientists. One challenge for scientists is to find appropriate collaborators in their research. The literature describes various solutions to the problem of expertise location, but most current approaches do not appear to be very suitable for expert recommendations in biomedical research. In this study, we present the development and initial evaluation of a vector space model-based algorithm to calculate researcher similarity using four inputs: 1) MeSH terms of publications; 2) MeSH terms and author rank; 3) exploded MeSH terms; and 4) exploded MeSH terms and author rank. We developed and evaluated the algorithm using a data set of 17,525 authors and their 22,542 papers. On average, our algorithms correctly predicted 2.5 of the top 5/10 coauthors of individual scientists. Exploded MeSH and author rank outperformed all other algorithms in accuracy, followed closely by MeSH and author rank. Our results show that the accuracy of MeSH term-based matching can be enhanced with other metadata such as author rank
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
Get PDFBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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
Scholarly Communication and Publishing Lunch and Learn Talk #11: The ULS Open Access Author Fee Fund
No full textAt the May 2014 talk, you will learn about the ULS Open Access Author Fee Fund--what it is, why we do it, how it works, and how the program is going so far
The R&D Tax Incentives
No full textThis article sets out some background information and reflections of the author on the R&D tax incentive schemes included in the Common Corporate Tax Base (CCTB) Proposal. In particular the author analyzes the stimulus to private R&D through ad hoc tax incentives included in the CCTB Proposal and dives into the actual provisions included in the Proposal highlighting the most relevant issues connected with their design and interpretation. Moreover, the author explores the interaction between the CCTB Proposal and the granting by Member States of domestic R&D tax incentives
Cardiac Troponin I release following coronary artery bypass surgery. Effects on operative and mid-term survival
No full textObjective: Myocardial infarction (MI) associated with coronary artery bypass grafting (CABG) operations represents a serious and relatively frequent peri-operative complication. Markers of myocardial necrosis are usually found elevated in patients undergoing coronary bypass operation with cardiac arrest. Cardiac troponin I (cTnI) is the preferred marker to detect acute myocardial ischemia. Its ability to predict short and, particularly, midterm outcome following coronary bypass operations is uncertain. The aim of the presented study is to assess the role of postoperative cTnI in predicting in-hospital and mid-term outcome in non-selected patients undergoing CABG and to suggest a critical use of cTnI to improve post-operative care of patients with elevated troponin release. Methods: Between May 2000 and February 2003, 230 unselected patients undergoing surgical revascularization had cTnI measured preoperatively and 11 times postoperatively. Patients with unstable angina and recent MI (<7 days) were included in the study. Patients undergoing aortic dissection surgery and those undergoing heart valve procedures with associated CABG as well as patients transferred on emergency in the operative room following complicated percutaneous coronary intervention were excluded. A receiver operating characteristics (ROC) curve was constructed using cTnI postoperative peak values to assess prognostic specificity and sensitivity of the test. 13 ng/ml is the cut-off value used to assess the prognostic significance of peak cTnI postoperative release for short and mid-term outcome for mortality and hospitalization for cardiac causes. Mean and maximal follow-up were 22.6±10.7 and 48.3 months, completeness 90%. Results: 146 patients (63.5%) had postoperative cTnI peak values <13 ng/ml (mean peak value 6.6±3.1 ng/ml), 84 patients (36.5%) had postoperative cTnI peak values >13 ng/ml (mean peak value 45.5±59.9 ng/ml). Patients with peak cTnI >13 ng/ml were older, had lower body mass index and had higher preoperative cTnI values. They required longer cross-clamp time and CPB time. Post-operative results are shown. Hospital death was significantly higher in cTnI >13 ng/ml group (9.5% vs. 0.7%, P = 0.0009). = 0.0009). Multivariate analysis showed that cTnI >13 ng/ml was the only independent predictor of hospital death (OR 10.33, P = 0.04) and hospital death for = 0.04) and hospital death for cardiac causes. Two years follow-up demonstrate that cTnI postoperative release had no influence on mid-term mortality and hospitalization for cardiac causes.Conclusions: The presented is the largest study reporting mid-term survival for CABG patients based on postoperative cTnI release. CTnI is a valuable marker for immediate myocardial damage following coronary bypass operations. CTnI postoperative release does not predict mid-term outcome
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