1,721,077 research outputs found
Vagus nerve stimulation increases neurotrophins gene expression and alters cell proliferation in the rat hippocampus
No full textVagus nerve stimulation (VNS) is effective in patients with treatment-resistant epilepsy. More recently, VNS has been ap- proved for treatment-resistant depression; nevertheless, the molec- ular mechanism(s) underlying its therapeutic action remains un- clear. In light of the proven anticonvulsant properties of VNS, its modulation of neurochemical systems implicated in major de- pression and impact on neuronal functional activity and plasticity, we tested the possibility that VNS could promote the synthesis of neurotrophic factors (BDNF, bFGF and NGF) that promote survival, maintenance and proliferation of neuronal cells, in the rat brain. Moreover, we investigate whether VNS could interfere with neurogenesis in the hippocampal dentate gyrus.
RNase protection assay revealed that acute VNS increases the abundance of BDNF and bFGF mRNAs in the hippocampus, and do not significantly alters the abundance of NGF mRNA. Immunohistochemical studies demonstrate that VNS alters cell proliferation and neurogenesis in dentate gyrus, as demonstrated by the double labeling with specific antibodies for the nuclear neuronal protein NeuN and BrdU.
Our results suggest that VNS could trigger neuronal plastic changes and demonstrate that such stimulation induced an increase in the gene expression of BDNF and bFGF in the rat hippocampus. These increases in growth factors were associated with a disrup- tion of cell proliferation and neurogenesis process in the granule cell layer of the dentate gyrus. These new findings contribute to elucidate the molecular mechanisms underlying the action of VNS, a new therapeutic tool for the treatment of epilepsy and depression.
References
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Palma, E., Torchia, G., Limatola, C., Trettel, A., Arcella, A., Can- tore, G., Di Gennaro, G., Manfredi, M., Esposito, V., Quarato, P.P., Miledi, R., Eusebi, F., 2005. BDNF modulates GABAA receptors microtransplated from thehuman epileptic brain to Xenopus oocites. Proc Natl Acad Sci USA 102, 1667–1672
Therapeutic interventions and adjustments in the management of parkinson disease: Role of combined carbidopa/levodopa/entacapone (stalevo®)
No full textParkinson disease (PD) is a neurodegenerative disorder characterized by 3 cardinal motor symptoms: resting tremor, rigidity, and bradykinesia. Since its introduction 40 years ago, levodopa has represented the gold standard for dopaminergic stimulation therapy in patients with PD. Levodopa is routinely combined with a dopa-decarboxylase inhibitor (DDCI) to prevent the conversion of levodopa into dopamine in peripheral circulation. However, up to 80% of patients treated with continuous levodopa manifest the onset of disabling motor complications capable of producing an adverse effect on quality of life as the disease progresses. In recent years, a new, safe, and efficacious armamentarium of treatment options has been provided by the marketing of the catechol-O-methyltransferase (COMT) inhibitor, entacapone, a peripheral blocker of dopa to 3-0-methyldopa metabolism, which increments levodopa brain availability. When administered with levodopa, entacapone conjugates the rapid onset of levodopa-induced effects with a protracted efficiency, thus providing additional benefits to classic levodopa treatment by increasing “on” time in fluctuating PD patients, and theoretically providing a more continuous and physiological-like stimulation of dopamine receptors implying a reduced risk of motor complications. In this context, the use of a single administration of combined carbidopa/levodopa/entacapone (Stalevo®) in the treatment of PD affords clinical improvements similar to those obtained by 2 separate tablets (ie, levodopa/DDCI and entacapone), although the former produces a more positive effect on quality of life than the latter. Additionally, the STalevo Reduction In Dyskinesia Evaluation (STRIDE-PD) study was designed with the aim of demonstrating that the combination of levodopa, carbidopa, and entacapone, used as initial levodopa therapy, significantly delays the onset of dyskinesias compared with the conventional levodopa/carbidopa formulation. Unfortunately, STRIDE-PD failed to prove the benefit of continuous dopaminergic stimulation with triple therapy in a clinical setting. Recently, the effect of combined COMT inhibitor with levodopa administration in reducing homocysteine synthesis has been described. To this regard, clear evidence has been presented indicating homocysteine as a risk factor for vascular diseases, cognitive impairment, and dementia. Several studies have discussed the potential of entacapone as adjunct to levodopa/ DDCI in reducing plasma homocysteine levels with contrasting results
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
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