1,720,969 research outputs found
Microvesicles: neuroglial unconventional signaling to cortical brain cells
Full text linkExtracellular vesicles (EVs) represent an alternative and recently discovered way by which diverse cell phenotype can deliver complex messages through released vesicles and their cargoes to neighbor or distant targets. EVs mediate fundamental physiological and pathological processes in biological systems.
In particular, we focused on neuron-glia communication mediated by microvesicles (MVs), a subpopulation of EVs that directly originate by outward budding of cellular plasma membrane, which are mostly released under specific stimuli. Given the nanosized dimension and origin of MVs, we tested the ability of carbon-based nanomaterial (small graphene oxide nanoflakes, s-GO), which are demonstrated to interface cells and interact with their physiology at the level of their plasma membrane, to affect the mechanisms governing vesicles release. We first investigated whether s-GO affected the ability of astrocytes to release synaptic-like MVs in pure glial cultures. Our results describe the potential of GO nanosheets to alter different modes of interneuronal communication systems in the central nervous system (CNS). We further tested the reactivity of microglia, a sub-population of neuroglia that acts as the first active immune response, when challenged by chronic s-GO delivery at high doses. We investigated the tissue reactivity in 3D tissue models by using organotypic spinal cord cultures, ideally suited for studying long-term interference with cues delivered at controlled times and concentrations and in isolated neuroglia cultures. In the latter condition, we further tested the role of microglial micro-vesicle release in mediating cell responses to s-GO. Finally, starting from the observation that small graphene oxide flakes (s-GO) are able to boost MVs basal release in cortical glial cells of rodents after a sub-chronic treatment of 6-8 days, we compared through the use of highly sensitive and resolutive nanotechnological tools, MVs obtained under s-GO exposure with MVs obtained by stimulation with the purinergic agonist bzATP, known to induce such release in glial cells. The structural and macromolecular similarities found, suggested a comparable nature of s-GO-derived MVs with the bzATP-derived ones, despite the unusual induction of release. We finally investigated the acute effects of those populations of vesicles exerted on single cortical neurons by focusing on their synaptic activity. We found that both the MVs types
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induced an increase in spontaneous post synaptic currents (PSCs) on neurons, after 15 minutes from MVs administration
Modulation of climbing fibers intrinsic excitability can reshape the architecture of olivo-cerebellar circuit
No full textModulation of climbing fibers intrinsic excitability can reshape the architecture of the olivo-cerebellar circuit
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Activity-dependent structural plasticity of cerebellar climbing fibers and its functional consequences
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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
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