1,720,965 research outputs found
The P2 receptors in platelet function
No full textAfter vessel wall injury, platelets adhere to the exposed subendothelium, are activated, and release mediators such as thromboxane A2 (TXA 2) and nucleotides stored at very high concentration in the so-called dense granules. Among other soluble agents, released nucleotides act in a positive feedback mechanism to cause further platelet activation and amplify platelet responses induced by agents such as thrombin or collagen. Adenine nucleotides act on platelets through three distinct P2 receptors: two are G protein-coupled adenosine diphosphate (ADP) receptors, namely the P2Y 1 and P2Y12 receptor subtypes; the P2X1 receptor ligand-gated cation channel is activated by adenosine triphosphate (ATP). The P2Y1 receptor initiates platelet aggregation but is not sufficient for a full platelet aggregation in response to ADP, whereas the P2Y12 receptor is responsible for completion of the aggregation to ADP. This receptor, the molecular target of the antithrombotic drug clopidogrel, is responsible for most of the potentiating effects of ADP when platelets are stimulated by agents such as thrombin, collagen, or immune complexes. The P2X1 receptor is involved in platelet shape change and in activation by collagen under shear conditions. Each of these receptors is coupled to specific signal transduction pathways in response to ADP or ATP and is differentially involved in all of the sequential events involved in platelet function and hemostasis. As such, they represent potential targets for antithrombotic drugs. Copyrigh
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
The P2Y(1) receptor is normal in a patient presenting a severe deficiency of ADP-induced platelet aggregation - Further evidence for a distinct P2 receptor responsible for adenylyl cyclase inhibition
No full textADP is a key stimulus inducing platelet shape change and aggregation, a rise in internal calcium and inhibition of adenylyl cyclase. These signaling pathways are thought to be activated by three independent receptors, but to date only the P2Y1 receptor responsible for calcium mobilization and the ionotropic P2X1 receptor have been identified. We report here the characteristics of the P2Y1 receptor in a patient presenting a selective deficiency of ADP-induced aggregation. Cloning of the P2Y1 gene revealed that the patient's DNA and mRNA were normal. Pharmacological studies showed that the P2Y1 receptor was expressed and functional in patient's platelets. Hence, the P2Y1 receptor is not the cause of the impaired ADP-induced platelet aggregation in this patient. The PZX1 mRNA was also found to be present and normal. These findings add evidence to previous observations suggesting that a third P2 receptor coupled to adenylyl cyclase may be involved in ADP-induced platelet aggregation
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
MRS2500 [2-Iodo-N-6-methyl-(N)-methanocarba-2 '-deoxyadenosine-3 ',5 '-bisphosphate], a potent, selective, and stable antagonist of the platelet P2Y1 receptor with strong antithrombotic activity in mice
No full textThe platelet P2Y(1) ADP receptor is an attractive target for new antiplatelet drugs. However, because of the lack of strong and stable antagonists, only a few studies have suggested that pharmacological inhibition of the P2Y(1) receptor could efficiently inhibit experimental thrombosis in vivo. Our aim was to determine whether the newly described potent and selective P2Y(1) receptor antagonist MRS2500 [2-iodo-N-6-methyl-(N)-methanocarba-2'-deoxyadenosine-3',5'-bisphosphate ] could inhibit platelet function ex vivo and experimental thrombosis in mice in vivo. MRS2500 was injected intravenously into mice, and its effect on ex vivo platelet aggregation and in several models of thrombosis in vivo was determined. MRS2500 displayed high potency and stable and selective P2Y(1) receptor inhibition ex vivo. Although MRS2500 injection resulted in only moderate prolongation of the bleeding time, it provided strong protection in systemic thromboembolism induced by infusion of a mixture of collagen and adrenaline. MRS2500 also potently inhibited localized arterial thrombosis in a model of laser-induced vessel wall injury with two degrees of severity. Moreover, combination of MRS2500 with clopidogrel, the irreversible inhibitor of the platelet P2Y(12) receptor for ADP, led to increased antithrombotic efficacy compared with each alone. These results add further evidence for a role of the P2Y(1) receptor in thrombosis and validate the concept that targeting the P2Y(1) receptor could be a relevant alternative or complement to current antiplatelet strategie
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
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