1,720,978 research outputs found
Serotonin‐Elicited Amplification of Adenylate Cyclase Activity in Hippocampal Membranes from Adult Rat
No full textThe activity of the adenylate cyclase located in membranes prepared from hippocampus of adult rat can be stimulated by serotonin (5‐HT) (Ka= 4 x 10‐7M). The maximal effect is obtained with 10 μM 5‐HT. Freezing of the tissue decreases the 5‐HT stimulation; this stimulation is optimal in the presence of 82.5 mM Tris‐maleate buffer (pH 7.4) and 50 μM GTP. The adenylate cyclase activity of membranes prepared from cortex, hypothalamus, and colliculi of adult rats is not significantly stimulated by 5‐HT. Dopamine (DA) also stimulates adenylate cyclase located in hippocampal membranes; its effect can be blocked by haloperidol (10‐6 M), which fails to inhibit 5‐HT stimulation. Moreover, p‐chlorophenylalanine treatment for 2 weeks or selective lesion of 5‐HT axons afferent to the hippocampus increases the Vmax of 5‐HT stimulation, but fails to change that of DA stimulation. The 5‐HT stimulation can be inhibited by metergoline, spiroperidol, and pizotyline (10‐6 M), but not by the same concentrations of mianserin, ketanserine, alprenolol, phenoxybenzamine, and mepyramine. The 5‐HT stimulation of adenylate cyclase of hippocampal membranes can be mimicked by tryptamine, 5‐methoxytryptamine, bufotenine, and to a lesser extent by LSD; N‐methyltryptamine, N‐methyltryptophan, and 5‐hydroxytryptophan are inactive. Studies with kainic acid suggest that the 5‐HT recognition site (5‐HT1) linked to adenylate cyclase is located on the membrane of intrinsic hippocampal neurons. Copyright © 1983, Wiley Blackwell. All rights reserve
On the mode of action of imipramine: Relationship between serotonergic axon terminal function and down-regulation of β-adrenergic receptors
No full textRecognition sites for [3H]imipramine and I3H]mianserin are located in different structures and regulate different neuronal functions. Recognition sites for [3H]imipramine are located on serotonergic terminals, are part of the supramolecular organization of the uptake mechanisms and can be down-regulated by prolonged administration of the drug. When the number of recognition sites for imipramine is down-regulated, uptake of 5-hydroxytryptamine (5HT) in rat brain hippocampal slices is increased. The presence of the binding sites for imipramine in 5HT terminals is essential to mediate the down-regulation of recognition sites for norepinephrine (NE) and NE-mediated stimulation of adenylate cyclase. Mianserin binds on a site that is modulated by 5HT, the number of its binding sites is not down-regulated by repeated treatment and, like imipramine, decreases the NE-dependent cyclase but nbt the number of β-adrenergic receptor recognition sites. Repeated treatment with imipramine and mianserin down-regulated the number of 5HT2 recognition sites. Several lines of evidence indicate that binding site for mianserin is related but not identical to the 5HT2 receptor binding site. © 1983
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
Approaching coronavirus disease 2019: Mechanisms of action of repurposed drugs with potential activity against SARS-CoV-2
Full text linkOn March 11, 2020, the World Health Organization (WHO) declared the severe acute respiratory syndrome caused by coronavirus 2 (SARS-CoV-2) a global pandemic. As of July 2020, SARS-CoV-2 has infected more than 14 million people and provoked more than 590,000 deaths, worldwide. From the beginning, a variety of pharmacological treatments has been empirically used to cope with the life-threatening complications associated with Corona Virus Disease 2019 (COVID-19). Thus far, only a couple of them and not consistently across reports have been shown to further decrease mortality, respect to what can be achieved with supportive care. In most cases, and due to the urgency imposed by the number and severity of the patients’ clinical conditions, the choice of treatment has been limited to repurposed drugs, approved for other indications, or investigational agents used for other viral infections often rendered available on a compassionate-use basis. The rationale for drug selection was mainly, though not exclusively, based either i) on the activity against other coronaviruses or RNA viruses in order to potentially hamper viral entry and replication in the epithelial cells of the airways, and/or ii) on the ability to modulate the excessive inflammatory reaction deriving from dysregulated host immune responses against the SARS-CoV-2. In several months, an exceptionally large number of clinical trials have been designed to evaluate the safety and efficacy of anti-COVID-19 therapies in different clinical settings (treatment or pre- and post-exposure prophylaxis) and levels of disease severity, but only few of them have been completed so far. This review focuses on the molecular mechanisms of action that have provided the scientific rationale for the empirical use and evaluation in clinical trials of structurally different and often functionally unrelated drugs during the SARS-CoV-2 pandemic
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
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