Démarche diagnostique dans la Sclérose en Plaques

Il n'existe aucun marqueur biologique, aucun test diagnostique spécifique de la sclérose en plaques (SEP). Seul l'examen neuropathologique pourrait apporter une preuve diagnostique solide, mais il est exceptionnellement réalisé. Ainsi, le diagnostic repose à la fois sur la combinaison de critères cliniques et paracliniques en vue de démontrer la dissémination des lésions dans le temps et dans l'espace, et également sur l'exclusion des autres diagnostics possibles. L'objet de ce travail a été de définir une approche diagnostique de la SEP basée sur l'évolution des critères paracliniques liée aux améliorations techniques des moyens d'investigation. Des critères diagnostiques reposant essentiellement sur des arguments cliniques ont d'abord été proposés. Avec les progrès technologiques dans l'analyse du LCR et des potentiels évoqués et en particulier avec l'avènement de l'IRM, une nouvelle classification a été proposée par Poser et al. en 1983. Une réactualisation toute récente (McDonald et al. 2001) donne à l'IRM une place primordiale lui permettant de prouver la dissémination spatiale et temporelle des lésions dès le premier événement démyélinisant. Mais le diagnostic de SEP doit rester un diagnostic d'élimination. L'exclusion des pathologies pouvant mimer la SEP est donc requise. Nous avons montré qu'elles sont nombreuses et variées et que des éléments paracliniques, notamment l'analyse du LCR et l'IRM, pouvaient aider à les différencier de la SEP. Toutefois, dans les cas cliniques présentés, nous avons constaté que ces éléments n'étaient pas toujours suffisants. C'est alors la recherche d'atypies dans la présentation clinique et l'existence de perturbations biologiques, qui nous ont permis de mettre en doute le diagnostic de SEP et de rechercher un autre diagnostic. Au terme de cette étude, nous proposons qu'un bilan biologique soit intégré à titre systématique dans la démarche diagnostique permettant ainsi de retenir le diagnostic de SEP avec un maximum de certitudes.GRENOBLE1-BU Médecine pharm. (385162101) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

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Semantic compensation and novel word learning in university students with dyslexia

International audienceThe aim of this experiment was to use behavioral and electrophysiological methods to compare university students with dyslexia and matched skilled readers in a novel word learning experiment that included phonological categorization tasks, a word learning phase and a test phase with matching and semantic tasks. Specifically, we aimed at disentangling two hypotheses. If phonological processing drives novel word learning and if phonological processing is impaired in students with dyslexia, they should perform lower than skilled readers not only in the phonological categorization tasks but also in the matching and semantic tasks. By contrast, if students with dyslexia use semantic knowledge to compensate for their phonological deficits, should be able to reach the same level of performance and show similar enhancements of the N200 and N400 components than skilled readers in the matching and semantic tasks. Results at both behavioral and electrophysiological levels showed that the phonological deficits evidenced in the phonological tasks did not impede students with dyslexia to learn the meaning of novel words, possibly because they mobilized more frontal resources than skilled readers. These results are discussed within a general framework of semantic compensation in adults with dyslexia

Reducing canonical Wingless/Wnt signaling pathway confers protection against mutant Huntingtin toxicity in Drosophila.

International audienceHuntington's disease (HD) is a genetic neurodegenerative disease characterized by movement disorders, cognitive decline and neuropsychiatric symptoms. HD is caused by expanded CAG tract within the coding region of Huntingtin protein. Despite major insights into the molecular mechanisms leading to HD, no effective cure is yet available. Mutant Huntingtin (mHtt) has been reported to alter the stability and levels of β-Catenin, a key molecule in cell adhesion and signal transduction in Wingless (Wg)/Wnt pathway. However it remains to establish whether manipulation of Wg/Wnt signaling can impact HD pathology. We here investigated the phenotypic interactions between mHtt and Wg/Wnt signaling by using the power of Drosophila genetics. We provide compelling evidence that reducing Armadillo/β-Catenin levels confers protection and that this beneficial effect is correlated with the inactivation of the canonical Wg/Wnt signaling pathway. Knockdowns of Wnt ligands or of the downstream transcription factor Pangolin/TCF both ameliorate the survival of HD flies. Similarly, overexpression of one Armadillo/β-Catenin destruction complex component (Axin, APC2 or Shaggy/GSK-3β) increases the lifespan of HD flies. Loss of functional Armadillo/β-Catenin not only abolishes neuronal intrinsic but also glia-induced alterations in HD flies. Our findings highlight that restoring canonical Wg/Wnt signaling may be of therapeutic value

Processing interactions between phonology and melody: vowels sing but consonants speak.

The aim of this study was to determine if two dimensions of song, the phonological part of lyrics and the melodic part of tunes, are processed in an independent or integrated way. In a series of five experiments, musically untrained participants classified bi-syllabic nonwords sung on two-tone melodic intervals. Their response had to be based on pitch contour, on nonword identity, or on the combination of pitch and nonword. When participants had to ignore irrelevant variations of the non-attended dimension, patterns of interference and facilitation allowed us to specify the processing interactions between dimensions. Results showed that consonants are processed more independently from melodic information than vowels are (Experiments 1-4). This difference between consonants and vowels was neither related to the sonority of the phoneme (Experiment 3), nor to the acoustical correlates between vowel quality and pitch height (Experiment 5). The implication of these results for our understanding of the functional relationships between musical and linguistic systems is discussed in light of the different evolutionary origins and linguistic functions of consonants and vowels.Journal ArticleResearch Support, Non-U.S. Gov'tSCOPUS: ar.jinfo:eu-repo/semantics/publishe

Relations between phonology and melody in the perception and the memorization of songs

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Redox state, microstructure and viscosity of a partially crystallized basalt melt

International audienceAs measured in air above the glass transition range, the viscosity of an alkali basalt increases markedly with time by about two orders of magnitude in 12 h. This effect is essentially physical and due to the presence of microcrystals although partial crystallization of the melt into spinel and an SiO 2-poor pyroxene leads to a considerable enrichment in silica of the residual liquid. Partial crystallization depends strongly on the initial redox state of samples in that the presence of ferrous iron is required for spinel crystals to form and for pyroxene to nucleate and grow around them. Other measurements show that the viscosity of the crystal-free liquid decreases slightly with increasing ratios r=Fe 2+/∑Fe because the differences between samples with r=0.16 and 0.83 amount to about 1.5 and 0.3 log-units at 950 and 1400 K, respectively. Comparisons of the viscosities of the residual liquid matrix and of the initially crystal-free basalt show that physical effects caused by the presence of microcrystals begin to be observed at a low crystal fraction of 5 vol%. Finally, a model of viscosity calculation is developed for the melts which reproduces all data obtained in this work to better than 10%

Interactions between phonological and melodical dimensions of songs

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Perceptual Interactions between lyrics and tunes: Vowels sing but consonants speak

info:eu-repo/semantics/nonPublishe