1,721,044 research outputs found
Neurobiology of migraine
No full textMigraine - an episodic headache - affects more than 10% of the general population. Despite recent progress, drug therapy for preventing and treating migraine remains unsatisfactory for many patients. One problem that slows the development of new therapeutic approaches is our limited understanding of migraine neurobiology. Activation of the trigeminovascular system is a central step in the development of migraine. However, two main issues remain incompletely understood: the primary cause of migraine, leading to activation of the trigeminovascular system, and the mechanisms of pain generation after its activation
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
Familial hemiplegic migraine mutations increase Ca2+ influx through single human Ca(V)2.1 channels and decrease maximal Ca(V)2.1 current density in neurons
No full textInsights into the pathogenesis of migraine with aura may be gained from a study of human Ca(V)2.1 channels containing mutations linked to familial hemiplegic migraine (FHM). Here, we extend the previous single-channel analysis to human Ca(V)2.1 channels containing mutation V1457L. This mutation increased the channel open probability by shifting its activation to more negative voltages and reduced both the unitary conductance and the density of functional channels in the membrane. To investigate the possibility of changes in Ca(V)2.1 function common to all FHM mutations, we calculated the product of single-channel current and open probability as a measure of Ca(2+) influx through single Ca(V)2.1 channels. All five FHM mutants analyzed showed a single-channel Ca(2+) influx larger than wild type in a broad voltage range around the threshold of activation. We also expressed the FHM mutants in cerebellar granule cells from Ca(V)2.1alpha(1)(-/-) mice rather than HEK293 cells. The FHM mutations invariably led to a decrease of the maximal Ca(V)2.1 current density in neurons. Current densities were similar to wild type at lower voltages because of the negatively shifted activation of FHM mutants. Our data show that mutational changes of functional channel densities can be different in different cell types, and they uncover two functional effects common to all FHM mutations analyzed: increase of single-channel Ca(2+) influx and decrease of maximal Ca(V)2.1 current density in neurons. We discuss the relevance of these findings for the pathogenesis of migraine with aura
Molecular nature of anomalous L-type calcium channels in mouse cerebellar granule cells.
Full text linkSingle-channel analysis revealed the existence of neuronal L-type Ca2+ channels (LTCCs) with fundamentally different gating properties; in addition to LTCCs resembling cardiac channels, LTCCs with anomalous gating were identified in a variety of neurons, including cerebellar granule cells. Anomalous LTCC gating is mainly characterized by long reopenings after repolarization following strong depolarizations or trains of action potentials. To elucidate the unknown molecular nature of anomalous LTCCs, we performed single-channel patch-clamp recordings from cerebellar granule cells of wild-type, Ca(v)1.3(-/-) and Ca(v)1.2DHP(-/-) [containing a mutation in the Ca(v)1.2 alpha(1) subunit that eliminates dihydropyridine (DHP) sensitivity] mice. Quantitative reverse transcription-PCR revealed that Ca(v)1.2 accounts for 89% and Ca(v)1.3 for 11% of the LTCC transcripts in wild- type cerebellar granule cells, whereas Ca(v)1.1 and Ca(v)1.4 are expressed at insignificant levels. Anomalous LTCCs were observed in neurons of Ca(v)1.3(-/-) mice with a frequency not different from wild type. In the presence of the DHP agonist (+)-( S)- 202- 791, the typical prepulse- induced reopenings of anomalous LTCCs after repolarization were shorter in Ca(v)1.2DHP(-/-) neurons than in Ca(v)1.3(-/-) neurons. Reopenings in Ca(v)1.2DHP(-/-) neurons in the presence of theDHPagonist were similar to those in wild- type neurons in the absence of the agonist. These data show that Ca(v)1.2 alpha(1) subunits are the pore- forming subunits of anomalous LTCCs in mouse cerebellar granule cells. Given the evidence that Ca(v)1.2 channels are specifically involved in sustained Ras- MAPK (mitogen-activated protein kinase)- dependent cAMP response element- binding protein phosphorylation and LTCC-dependent hippocampal long- term potentiation (LTP) ( Moosmang et al., 2005), we discuss the hypothesis that anomalous rather than cardiac-type Ca(v)1.2 channels are specifically involved in LTCC-dependent and gene transcription- dependent LTP
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
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