1,720,955 research outputs found
Hybrid myocardial imaging for risk stratification prior to kidney transplantation : added value of coronary calcium and epicardial adipose tissue
No full textBACKGROUND:
Patient selection and optimal approach to risk stratification prior to kidney transplantation remain uncertain. We sought new predictors of an abnormal myocardial perfusion (MYP) stress test result.
METHODS:
Retrospective study of 411 consecutive chronic kidney disease stages 4-5D patients awaiting kidney transplantation referred for risk stratification. PET-CT or SPECT-CT was used to assess MYP and quantify coronary artery calcium (CAC) and epicardial adipose tissue (EAT). Abnormal MYP was defined as a perfusion defect involving ≥5% of the left ventricular myocardium.
RESULTS:
Fixed or reversible MYP defects were present in 41 patients (10%). Male sex, smoking, and history of cardiovascular disease were more prevalent; age was higher and CAC and EAT were greater in patients with MYP defects than in those with normal MYP. On multivariate logistic regression, EAT and CAC were independent predictors of abnormal MYP while diabetes mellitus showed a borderline association (P = .08). EAT added incremental diagnostic value to a model including age, CAC and diabetes mellitus [AUC 0.73 (95% CI 0.64-0.81) to 0.76 (95% CI 0.68-0.84; P = .02)]. Furthermore, the model containing EAT showed improved diagnostic discrimination.
CONCLUSIONS:
Abnormal MYP on screening stress testing appears to be rare in patients awaiting kidney transplantation suggesting an excess of testing. EAT and CAC may help predict what patients are at higher risk of developing abnormalities of MYP under stress.
Comment in
Does hybrid imaging have a role in cardiac risk evaluation of the pre-renal transplant patient? [J Nucl Cardiol. 2013
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
Vitamin D status and coronary flow reserve measured by positron emission tomography : a co-twin control study
Full text linkContext: Vitamin D insufficiency is associated with increased cardiovascular events in the general population. Additionally, low serum 25-hydroxyvitamin D [25(OH)D] is associated with endothelial dysfunction and arterial stiffness. However, little is known about the association between serum 25(OH)D level and myocardial blood flow. Objective: Our objective was to examine the association between serum 25(OH)D levels and coronary flow reserve (CFR) measured by N-positron emission tomography in asymptomatic middle-aged male twins. Design: The Emory Twin Study is a cross-sectional study of soldiers from the Vietnam Era Registry. Setting: The study was conducted at the General Clinical Research Center, Emory University, Atlanta, GA. Participants: A total of 368 middle-aged male twins were enrolled for the study. Serum 25(OH)D levels were measured in all subjects and classified as vitamin D insufficiency [25(OH)D <30 ng/ml] or sufficiency [25(OH)D ≥30 ng/ml]. Positron emission tomography with [ N]ammonia was used to evaluate myocardial blood flow at rest and after adenosine stress. CFR was measured as the ratio of maximum to rest myocardial blood flow. Main Outcome Measure: Primary outcome was CFR measurement. Results: Mean overall serum 25(OH)D concentration was 37.0 ± 21.4 ng/ml; 167 twins (45%) were vitamin D insufficient. CFR was significantly lower in subjects with vitamin D insufficiency compared with subjects with vitamin D sufficiency (2.41 vs. 2.64; P = 0.007), even after adjustment for traditional cardiovascular risk factors, serum PTH, calcium, and phosphorus levels, and season. An abnormal CFR (CFR <2) was more prevalent in subjects with vitamin D insufficiency than with vitamin D sufficiency (31 vs. 20%; P = 0.03). In addition, in vitamin D status-discordant twin pairs, CFR was significantly lower in the vitamin D-insufficient twin than in the vitamin D-sufficient co-twin (2.35 vs. 2.58; P = 0.037). Conclusion: Vitamin D insufficiency is associated with lower CFR in men. This association may help explain some of the increased cardiovascular risk reported in individuals with vitamin D insufficiency
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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