1,720,988 research outputs found
Pathophysiology and management of fatigue in multiple sclerosis
No full textLa fatigue est un symptôme fréquent chez les patients atteints de sclérose en plaques (SEP). Malgré la gravité de ce symptôme, sa physiopathologie demeure vague et ses traitements sont insatisfaisants dans la majorité des cas. L’objectif de ce travail était de comprendre les mécanismes sous-jacents de la fatigue liée à la SEP, et tester les effets de la stimulation électrique transcrânienne (tDCS) sur ce symptôme. Dans une première étude (revue de littérature), on a analysé les données disponibles sur la physiopathologie de la fatigue dans la SEP, et on a identifié une boucle cortico-striato-thalamo-corticale associée à ce symptôme. On a trouvé que, sur le plan neuropsychologique, les symptômes affectifs sont les corrélats les plus pertinents. Cependant, les corrélats neurophysiologiques de ce symptôme sont peu étudiés et une discordance existe dans la littérature quant aux résultats rapportés par les divers travaux. Ensuite, dans une deuxième étude, on a effectué une évaluation physiopathologique de la fatigue chez 38 patients atteints de SEP. Les patients fatigués avaient, par rapport à ceux non fatigués, une symptomatologie affective plus prononcée, une inhibition intracorticale plus élevée et des anomalies cortico-sous-corticales touchant les noyaux caudés et le cortex pariétal. Les résultats neuropsychologiques de ce travail suggèrent des mécanismes sous-jacents communs ainsi que des relations bidirectionnelles entre la fatigue et les symptômes affectifs. Les résultats neurophysiologiques reflètent des processus de plasticité mal adaptative à l’origine de la fatigue. Les résultats radiologiques soutiennent la présence d’une boucle cortico-sous-corticale à la base de la perception de la fatigue dans la SEP. Dans une troisième étude, on s’est intéressé à étudier, chez 27 patients, la neurophysiologie des symptômes affectifs associés à la fatigue dans la SEP. Une association significative a été observée entre l'alexithymie et la période de silence corticale. Les résultats mettent en évidence la relation entre l'alexithymie et une transmission gabaergique défectueuse, et concordent avec des travaux antérieurs réalisés chez des sujets sains et des patients souffrant de troubles de la personnalité. Dans une quatrième étude, on a effectué une revue de la littérature sur la place de la tDCS dans le traitement de la fatigue de la SEP, et on a identifié quelques travaux qui ont rapporté des résultats prometteurs obtenus en réponse à une stimulation anodique des régions sensorimotrices. Ensuite, dans une cinquième étude, on a évalué la place de la tDCS anodique préfrontale gauche ou pariétale droite dans le traitement de la fatigue liée à la SEP. 10 patients fatigués atteints de SEP ont été inclus dans une étude croisée randomisée contrôlée en double aveugle (stimulation anodique réelle ou placebo ciblant le cortex préfrontal gauche ou pariétal droit). Seule la stimulation active préfrontale gauche s’est avérée efficace sur la fatigue. Enfin, du fait de la possibilité de prolonger et de potentialiser les effets en multipliant les séances de stimulation, on a appliqué dans une dernière étude, 14-19 séances de tDCS anodique préfrontale gauche chez deux patients ; cette intervention a permis de maintenir, sur plusieurs semaines, les effets bénéfiques de la tDCS sur la fatigue et améliorer d’autres mesures cognitives et affectives. Compte tenu du caractère handicapant de la SEP, des projets futurs pourraient tester l’application de la tDCS à domicile, avec un outil de stimulation bien sécurisé et un contrôle technique supervisé à distance afin de s’assurer du bon déroulement des séances et maximiser les bénéfices. Aussi, un couplage de la tDCS à des techniques de psychothérapie, notamment la thérapie cognitivo-comportementale, semble avoir une place dans l’arsenal thérapeutique de ce symptôme et mérite d’être évalué dans l’avenir proche.Fatigue is a common symptom that dramatically affects the quality of life of patients with multiple sclerosis (MS). Despite the severity of this symptom, its pathophysiology remains vague and diverse, and its available treatments are unsatisfactory in the majority of cases. The aim of this work was to understand the underlying mechanisms of fatigue in MS, and then to conduct a therapeutic study to assess the effects of transcranial direct current stimulation (tDCS) on fatigue in MS patients.In a first study (literature review), the available data on the pathophysiology of fatigue in MS were analyzed, and a cortico-striato-thalamo-cortical loop associated with this symptom was identified. Affective symptoms constitute the most pertinent neuropsychological correlates. Neurophysiological data are scarce and inconsistent across the studies. Then, in a second study, a multidisciplinary assessment of fatigue was performed in 38 MS patients. Compared to non-fatigued patients, fatigued ones had higher scores of affective symptoms; higher intracortical inhibition; and cortico-subcortical abnormalities (caudate nuclei and parietal cortex). The neuropsychological findings suggest common underlying mechanisms as well as bidirectional relationships between fatigue and affective symptoms. The neurophysiological findings may reflect maladaptive plasticity processes behind the generation of fatigue. The radiological findings support the existence of a cortico-subcortical loop at the basis of MS fatigue. In a third study, the neurophysiology of affective symptoms associated with MS fatigue was assessed in 27 patients. A significant association was found between alexithymia and the cortical silent period. These results highlight the relationship between alexithymia and defective GABAergic transmission and are consistent with previous work in healthy subjects and patients with personality disorders.In a fourth study, a literature review was conducted on the use of tDCS to treat MS fatigue, and a few studies targeting the sensorimotor regions, and yielding promising antifatigue effects were identified. In a fifth study, the place of anodal prefrontal or parietal tDCS in the treatment of fatigue was assessed in 10 fatigued MS patients in a crossover randomized controlled double-blind study (active or sham anodal tDCS over the left prefrontal or right parietal cortex). Only active left prefrontal stimulation improved fatigue. This work proposes tDCS as a potential therapeutic tool for treating MS fatigue. Finally, based on recent literature supporting the idea of a cumulative effect following the repetition of stimulation sessions, several sessions of left prefrontal anodal tDCS (14-19 sessions) were performed in two patients; this intervention led to a long-term improvement of fatigue as well as an amelioration of other cognitive and affective manifestations.Since MS is a debilitating disease, future projects could test the application of home-based tDCS using a well-secured stimulation setting and a remotely supervised technical control in order to ensure a successful session performance and maximize the clinical benefits. In addition, coupling tDCS with some psychotherapeutic approaches, notably the cognitive-behavioral therapy, could have a place in the therapeutic armamentarium of MS fatigue and merits in-depth assessment in the near future
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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
Neurophysiological evalaution of cortical excitability and tremor in multiple sclerosis
No full textNotre travail a porté : 1) sur l'étude des modifications d'excitabilité corticale au cours du traitement des poussées de sclérose en plaques (SEP) et de l'évolution naturelle des formes progressives de SEP ; 2) sur la caractérisation du tremblement d'action, fréquemment observé dans le cadre de cette maladie et qui constitue une importante source de handicap. Ceci a conduit à la réalisation de 5 études. La première étude a démontré que l'amélioration rapide des performances motrices observées à la suite du traitement de poussées de SEP par une corticothérapie administrée en flash quotidien sur plusieurs jours, s'accompagnait de modifications significatives d'excitabilité corticale étudiée par stimulation magnétique transcrânienne. Ces modifications portaient sur la balance d'influences GABAergiques et glutamatergiques au sein du cortex moteur. Cette augmentation d'excitabilité survient bien avant toute possibilité de remyélinisation ou de régénérescence axonale et constitue donc une amélioration fonctionnelle induite par le traitement. Dans la deuxième étude, différents paramètres d'excitabilité corticale ont été suivis sur un an chez des patients présentant une forme progressive de SEP, traitée ou non traitée. Cette étude a mis en évidence une diminution de l'inhibition intracorticale et une augmentation du seuil moteur au repos chez les patients non traités, accompagnant une augmentation des scores cliniques de handicap. En revanche, les patients traités restaient stables, aussi bien sur le plan neurophysiologique que clinique. Ces résultats montrent que l'évolution de la SEP progressive est associée à une altération globale et évolutive de l'excitabilité du cortex moteur, portant aussi bien sur les neurones pyramidaux que sur les circuits de contrôle inhibiteur, probablement liée à l'aggravation de la perte neuronale au fil du temps. Nos résultats montrent également que différents types de traitement immunomodulateur peuvent arrêter ce cours évolutif. Dans une troisième étude, nous avons caractérisé l'existence d'un tremblement chez 32 patients atteints de SEP au moyen d'enregistrements électromyographiques et accélérométriques réalisés au membre supérieur. Ces enregistrements n'ont permis de confirmer l'existence d'un véritable tremblement que chez un seul patient. L'étude neurophysiologique concomitante de circuits de contrôle cérébelleux et protubérantiels a permis de montrer que la plupart des aspects cliniques de tremblement dans la SEP ne révélait en fait qu'un pseudo-tremblement lié en grande partie à des dysfonctions cérébelleuses. Nos deux dernières études ont permis de préciser ce résultat, au moyen d'une analyse du signal électromyographique et accélérométrique par décomposition modale empirique associée à une transformée de Hilbert-Huang. Cette méthode d'analyse apparaît valide et performante pour caractériser les tremblements et pseudo-tremblements survenant dans la SEP et les distinguer d'autres types de tremblement, comme le tremblement essentiel.Our work focused on: 1) the study of cortical excitability changes in the treatment of multiple sclerosis (MS) relapses and the natural history of progressive forms of MS; 2) the characterization of action tremor, which is frequently observed in the course of the disease and is a major source of disability. This has led to the realization of five studies. The first study demonstrated that a rapid improvement in motor performance can be observed following treatment of MS relapses by intravenous corticosteroids administered daily over several days, accompanied by significant changes in cortical excitability parameters studied by transcranial magnetic stimulation techniques. These changes focused on the balance between GABAergic and glutamatergic influences in the motor cortex. An increase in cortical excitability occurs well before any possibility of remyelination or axonal regeneration, demonstrating a functional improvement induced by the treatment. In the second study, different parameters of cortical excitability were followed over one year in patients with progressive MS, treated or untreated. This study showed a decrease of intracortical inhibition and increased motor threshold at rest in untreated patients, accompanying a worsening of clinical disability scores. In contrast, treated patients remained stable, both on clinical and neurophysiological parameters. These results show that the evolution of progressive MS is associated with a global and progressive impairment of motor cortex excitability, concerning both pyramidal neurons on inhibitory control circuits, probably due to the progression of cortical neuronal loss over time. Our results also showed that different types of immunomodulatory therapy can stop this evolutionary course. In a third study, we characterized the existence of action tremor in 32 MS patients using electromyographic and accelerometer recordings in the upper limb. These recordings confirmed the existence of a real tremor in only one patient. Concomitant neurophysiological study of cerebellar and pontine circuits of control showed that most of the clinical aspects of tremor in MS in fact revealed a pseudo-tremor largely due to cerebellar dysfunctions. Our last two studies have clarified this result by means of an analysis of the electromyographic and accelerometer signal using empirical mode decomposition associated with Hilbert-Huang transform. This method of analysis appears valid and effective to characterize tremor or pseudo-tremor occurring in MS patients and to distinguish them from other types of tremor, such as essential tremor
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
- …
