1,720,954 research outputs found
EFFECTS OF CYSTEINYL LEUKOTRIENES ON PLATELET ACTIVATION
Full text linkPlatelet are key players in haemostasis and represent a pivotal link between inflammation, immunity and atherogenesis. Cysteinyl leukotrienes (CysLTs) such as LTC4, LTD4, and LTE4 are potent lipid inflammatory mediators which interact with G protein-coupled receptors, CysLT1R, CysLT2R . However, LTE4, the most stable cystenyl leukotriene, is not putative substrate for these two receptor. Recently have been hypothesized that a third cystenyl leukotreine receptor exists, and a computer modeling suggests P2Y12, receptor for ADP present on platelet surface, as the putative receptor. But GPR99 is also hypothesized as LTE4 putative receptor. It is known that LTE4 needs P2Y12 on platelet to mediate inflammation in sensitized mice, and LTC4 can induce release of P-selectin in sensitized mice. In human platelet LTE4 cannot increase level of cAMP, or of p-selectin.
Aim of this study was to test whether cystenyl leukotrienes elicit platelet functional responses, by interacting with the platelet P2Y12, receptor for ADP.
We measure the platelet aggregation induced by CysLTs alone or in combination with epinephrine or ADP; the cAMP level in presence of PGE1, ADP and CysLTs, and finally the p-selectin expression on platelet surface after stimulation with ADP and CysLTs and in presence/absence of cangrelor.
Ours results shows that CysLTs cannot affect platelet aggregation alone or in combination with other agonist, independently of presence of physiological level of calcium.
CysLTs failed to show an effect also on cAMP level. Also when platelet activation was tested by measuring the expression of p-selectin on the platelet membrane induced by ADP, CysLTs failed to show any effect.
The negative results of our studies are not due to alterations of the CysLTs that we used, as they were identified correctly at mass spectrometry and induced normal cellular response of HUVEC, as previously shown. The inflammatory effects of CysLTs mediated by the platelet P2Y12 receptor, which have been demonstrated in vivo experiments, were most likely indirect, rather than induced by a direct interaction of CysLTs with platelets
Inhibition of the platelet P2Y12 receptor for adenosine diphosphate does not impair the capacity of platelet to synthesize thromboxane A2
No full textAims Patients with acute coronary syndromes (ACSs) are treated with acetylsalicylic acid (ASA) and antagonists of the P2Y12 receptor (P2Y12R) for adenosine diphosphate (ADP). Based on the demonstration that P2Y12R antagonists inhibit thromboxane A2 (TxA2) production (target of ASA), it was surmised that ACS patients might be treated with P2Y12R antagonists only. However, this demonstration contrasts with the results of previous studies. The aim of this study was to test whether P2Y12R antagonists have off-target/indirect inhibitory effects on platelet TxA2 production.
Methods and results We studied 3 patients with inherited P2Y12R deficiency and 33 healthy subjects. Serum TxB2 (TxA2 metabolite) levels were similar in P2Y12R-deficient patients and healthy subjects and were not decreased by P2Y12R antagonists in vitro. Serum TxB2 levels did not decrease in 20 patients treated with prasugrel (10 mg q.i.d.) or placebo for 14 days. Arachidonic acid- and collagen-induced platelet aggregation (PA) and TxB2 production in platelet-rich plasma (PRP) of healthy subjects were inhibited in vitro by P2Y12R antagonists. However, P2Y12R antagonists did not inhibit TxB2 production when PA was prevented by avoiding the stirring of PRP in the aggregometer. The P2Y1 ADP-receptor antagonist MRS2500 had similar effects on PA and TxB2 production as P2Y12R antagonists. Acetylsalicylic acid inhibited TxB2 production more effectively than a P2Y12R antagonist; only the combination of ASA and a P2Y12R antagonist inhibited PA induced by high concentration of collagen.
Conclusion Inherited deficiency or pharmacological inhibition of P2Y12R does not affect the platelet capacity to synthesize TxA2. There is no pharmacological evidence that ACS patients may be safely treated with P2Y12R antagonists without ASA
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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