1,721,016 research outputs found
Non steroidal anti-inflammatory drugs and neurogenesis in the adult mammalian brain
No full textNon steroidal anti-inflammatory drugs (NSAIDs) are therapeutic agents of first choice for the treatment of inflammation, pain, and fever. Neuroscience research of the last decades has pointed out the important role of inflammation in the pathogenesis of several brain disorders, and epidemiological and experimental evidence has suggested a beneficial role of NSAIDs in both chronic and acute neuropathologies. More recently NSAIDs have gained further attention as potential tools to enhance neuroregenerative processes in the adult mammalian brain. The rational behind their use arises from the notion that inflammatory processes that accompany brain damage would exert a major detrimental effect on endogenous neurogenesis. However, inflammation and glial responses to acute or chronic injuries constitute a complex and multifaceted process by which, besides potentially harmful and cytotoxic activities, beneficial responses can be initiated in the attempt to re-establish the lost tissue integrity. The individuation of optimal timing and type of pharmacological intervention able to potentiate the beneficial aspects of inflammation rather than to suppress it as a whole, would allow the achievement of enhanced and successful regenerative responses. In the present article, we will review the current literature on the effects of NSAIDs on neurogenesis and briefly discuss the cellular or molecular mechanisms by which these drugs can modulate brain restorative processes. © 2008 Bentham Science Publishers Ltd
Pro-gliogenic effect of IL-1α in the differentiation of embryonic neural precursor cells in vitro
No full textInflammation is regarded as a main obstacle to brain regeneration. Major detrimental effects are attributed to microglial/macrophagic products, such as TNF-α and interleukin (IL)-6. The role of cytokines of the IL-1 family, particularly of IL-1α, in the modulation of neural precursor cell (NPC) properties is less characterized. IL-1α is one of the most abundant cytokines released upon acute stimulation of microglia with lipopolysaccharide and is down-regulated upon chronic stimulation. As we recently demonstrated, acutely activated microglia reduces NPC survival, prevent neuronal differentiation and promote glial differentiation. Chronically activated microglia are instead permissive to NPC survival and neuronal differentiation, and less effective in promoting astrocytic differentiation. We thus investigated whether IL-1α could contribute to the effects of acutely activated microglia on NPC. We found that NPC express functional IL-1 receptors and that exposure to recombinant IL-1α strongly enhances NPC differentiation into astrocytes, without affecting cell viability and neuronal differentiation. In the same conditions, recombinant IL-1β has pro-gliogenic effects at concentrations 10-fold higher than those found in activated microglial conditioned media. Interestingly, immunodepletion of IL-1α in activated microglial conditioned media fails to revert microglial pro-gliogenic action and slightly enhances neuronal differentiation, revealing that other microglial-derived factors contribute to the modulation of NPC properties. © 2010 International Society for Neurochemistry
In vitro neuronal and glial differentiation from embryonic or adult neural precursor cells are differently affected by chronic or acute activation of microglia
No full textThe contribution of microglia to the modulation of neurogenesis under pathological conditions is unclear. Both pro- and anti-neurogenic effects have been reported, likely reflecting the complexity of microglial activation process. We previously demonstrated that prolonged (72 hr) in vitro exposure to lipopolysaccharide (LPS) endows microglia with a potentially neuroprotective phenotype, here referred as to "chronic". In the present study we further characterized the chronic phenotype and investigated whether it might differently regulate the properties of embryonic and adult neural precursor cells (NPC) with respect to the "acute" phenotype acquired following a single (24 hr) LPS stimulation. We show that the LPS-dependent induction of the proinflammatory cytokines interleukin (IL)-1 alpha, IL-1 beta, IL-6, and tumor necrosis factor (TNF)-alpha was strongly reduced after chronic stimulation of microglia, as compared with acute stimulation. Conversely, the synthesis of the anti-inflammatory cytokine IL-10 and the immunomodulatory prostaglandin E-2 (PGE(2)) was still elevated or further increased, after chronic LPS exposure, as revealed by real time PCR and ELISA techniques. Acutely activated microglia, or their conditioned medium, reduced NPC survival, prevented neuronal differentiation and strongly increased glial differentiation, likely through the release of proinflammatory cytokines, whereas chronically activated microglia were permissive to neuronal differentiation and cell survival, and still supported glial differentiation. Our data suggest that, in a chronically altered environment, persistently activated microglia can display protective functions that favor rather than hinder brain repair processes. (c) 2008 Wiley-Liss, Inc
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
- …
