1,721,032 research outputs found
Uptake of [N-methyl-C-11]propionyl-L-carnitine (PLC) in human myocardium
No full textWe studied the uptake of propionyl-L-carnitine from plasma by the myocardium in 10 human subjects using positron emission tomography. Propionyl-L-carnitine was labeled in the N-methyl position with carbon-11 (T 1/2 = 20 4 min) and administered i.v. in trace amounts. The uptake of the radiolabel by the myocardium was then scanned over a period of 1 1/2 h. The activity-time course of the tracer in blood and plasma and the exchange of the label in plasma between propionyl carnitine, acetyl carnitine and free carnitine was followed during the scans. Myocardial blood flow was also measured in the same subjects. The results show an exchange of the tracer between the myocardium and plasma, and they show an apparently irreversible component of uptake, a result consistent with the incorporation of the label into relatively large intracellular carnitine pools
Preparation of no-carrier-added [I-124]A(14)-iodoinsulin as a radiotracer for positron emission tomography
No full textA(14)-Iodoinsulin is a close biochemical and pharmacological mimic of insulin. Human insulin was labelled in its A chain tyrosine-14 residue by direct iodination with the positron-emitter iodine-124 (beta (+) = 25.6%; t(1/2) = 4.15 days) to provide a radiotracer for imaging with positron emission tomography (PET). Several reagents were compared for conversion of cyclotron-produced [I-124]iodide into a reactive species for the labelling reaction. Radiochemical yields from the use of Iodo-Gen (R), Chloramine-T, N-bromosuccinimide or lactoperoxidase-hydrogen peroxide were similar [35% (n = 1), 33 +/- 9% (n = 10), 32 +/- 11% (n = 25) or 33% (n = 2), respectively]. [I-124]A(14)-Iodoinsulin was separated from unreacted insulin and radioactive by-products by tandem reverse phase HPLC and rapidly formulated for intravenous injection by adsorption on a Sep-Pak (t)C18-Plus (R) cartridge, followed by elution with 10 mM hydrochloric acid-ethanol (1 : 1 v/v, 1 mi). This radiotracer can now be obtained in useful radioactivities at high effective specific radioactivity and is now being applied to PET studies of its biodistribution in living subjects. Copyright (C) 2001 John Wiley & Sons, Ltd
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
In vivo imaging of insulin receptors by PET: preclinical evaluation of iodine-125 and iodine-124 labelled human insulin
No full text[A(14)-*i]iodoinsulin was prepared for studies to assess the suitability of labeled iodoinsulin for positron emission tomography (PET). Iodine-125 was used to establish the methods and for preliminary studies in rats. Further studies and PET scanning in rats were carried out using iodino-124. Tissue and plasma radioactivity was measured as the uptake index (UI = {cpm.(g tissue)(-1)}/{cpm injected.(g body weight)(-1)}) at 1 to 40 min after intravenous injection of either [A(14)-I-125]iodoinsulin or [A(14)-I-124]iodoinsulin. For both radiotracers, initial clearance of radioactivity from plasma was rapid (T-1/2 similar to 1 min), reaching a plateau (UI = 2.8) at similar to 5 min which was maintained tot, 35 min. Tissue biodistributions of the two radiotracers were comparable; at 10 min after injection, UI for myocardium was 2.4, liver, 4.0, pancreas, 5.4, brain, 0.17, kidney, 22, lung, 2.3, muscle, 0.54 and fat, 0.28. Predosing rats with unlabelled insulin reduced the UI for myocardium (0.95), liver (1.8), pancreas (1.2) and brain (0.08), increased that for kidney (61) but had no effect on that for lung (2.5), muscle (0.50) or fat (0.34). Analysis of radioactivity in plasma demonstrated a decrease of [I-125]iodoinsulin associated with the appearance of labeled metabolites; the Percentage of plasma radioactivity due to [I-125]iodoinsulin was 40% at 5 min and 10% at 10 min. The heart, liver and kidneys were visualized using [I-124]iodoinsulin with PET. (C) 2002 Elsevier Science Inc. All rights reserved
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
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