Correlations between soluble alpha/beta forms of amyloid precursor protein and Abeta38, 40 and 42 in human cerebrospinal fluid

International audienceCerebrospinal fluid (CSF) biomarkers are now widely used for diagnosis of Alzheimer disease (AD) in atypical clinical forms, for differential and early diagnosis, or for stratification of patients in clinical trials. Among these biomarkers, different forms of amyloid peptides (Aβ) produced by the cleavage of a transmembrane precursor protein called APP (amyloid precursor protein) have a major role. Aβ peptides exist in different length the most common ones having 40 (Aβ40), 42 (Aβ42), or 38 (Aβ38) amino acids in length. APP processing by gamma-secretase releases also an amino-terminal secreted fragment called sAβPP-beta while an alternative nonamyloidogenic cleavage of APP, through an alpha-secretase, liberates another fragment called sAβPP-alpha. To decipher the molecular and pathological mechanisms leading to the production and the detection of these entities is essential for the comprehension and the prevention of AD. In this report, we present the results of the Keywords: Biomarkers CSF Soluble amyloid precursor proteins Aβ fragment peptides Alzheimer disease Dementi

Apports diagnostiques du 18F-MPPF en Tomographie par émission de Positons dans la maladie d Alzheimer

La maladie d Alzheimer (MA) est la principale cause de démence dégénérative. In vivo, seul un diagnostic probable de MA peut être porté, à partir des données cliniques et neuropsychologiques. Le développement de biomarqeurs spécifiques et susceptibles de discriminer les différentes phases de la MA constitue un enjeu majeur dans les perspectives d un diagnostic précoce et de l évaluation des interventions thérapeutiques. Des études récentes ont montré une modification du métabolisme sérotoninergique dans la MA. Dans une approche diagnostique précoce et différentiel de la MA, nous avons étudier le syste me sérotoninergique in vivo des patients MA à différents stades évolutifs et des patients atteints d autres types de démences grâce à la TEP au 18F-MPPF, qui permet d étudier les récepteurs sérotoninergiques 5-HT1A qui sont principalement localisés dans les régions limbiques, touchées précocement dans la MA. Nos résultats montrent que le système sérotoninergique est précocement affecté dans la MA et que son étude permet de discriminer la phase pré-démentielle de la maladie (aMCI) de la phase de démence légère, en suggérant la mise en place d un mécanisme compensatoire au stade précoce de la MA. Cette étude démontre que la TEP au 18F-MPPF est un outil intéressant pour l étude de la physiopathologie de la MA et qu elle est un outil de diagnostic précoce de la MAA probable diagnosis of Alzheimer s disease (AD) is possible during the life of the patient. Recent studies have shown modifications of the serotonergic metabolism in AD. In the early and differential diagnostic approach of AD, we have studied in vivo serotonergic system of AD patients at different stages of the disease and patients with other dementia with 18F-MPPF PET, which allows studying the 5-HT1A serotonergic receptors which mainly located the limbic structures, affected early in AD. Our results show that serotonergic system is early affected in AD, allowing the discrimination of AD at the different stages and with other dementia, suggesting the presence of a compensatory mechanism at the early stage of AD. This study shows that the 18F-MPPF PET is an interesting tool for the physiopathological study of AD and that it is a tool for early diagnosis of ADLYON1-BU.Sciences (692662101) / SudocSudocFranceF

Méningiomes du nerf optique traités par radiothérapie conformationnelle fractionnée (Résultats visuels à long terme et facteurs de mauvais pronostic)

BESANCON-BU Médecine pharmacie (250562102) / SudocSudocFranceF

Valeur pronostique de l'OCT (Optical Coherence Tomography) dans l'évaluation de la récupération visuelle des adénomes hypophysaires après traitement (étude prospective)

LYON1-BU Santé (693882101) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Optic ataxia revisited:

International audienceOptic ataxia and visual agnosia have been proposed to constitute a double dissociation which provides the main argument for the assimilation of the anatomical distinction between a dorsal and a ventral visual stream to the functional distinction between perception and action. In the present review, we argue that insufficient evidence has been collected to argue for this double dissociation. Several criteria are reviewed: (1) exploration of the visuomotor behavior in central versus peripheral vision has not been matched for the two types of patients; (2) the temporal constraints of visual processes that are impaired in the two neurological conditions appear to play a crucial role in the apparent dissociation; (3) the necessary reductionism of experimental conditions used to study action has led to an overconsideration of optic ataxia as a global deficit for action. Altogether optic ataxia appears to result from a specific impairment of immediate visuomotor control rather than of visually guided action as a whole. These results are discussed in the light of recent research on optic ataxia and on motor control, and directions for future research are proposed

Combination of attentional and spatial working memory deficits in Bálint-Holmes syndrome

International audienceThis study aims to investigate whether attention and spatiotemporal integration deficits are dissociated in patients with bilateral posterior cortical atrophy (PCA), and whether it is their combination that leads to a severe clinical handicap. We recorded performance and ocular behavior of four PCA patients and four age-matched controls in visual search and counting tasks. We measured the percentage of targets detected and the mean detection time in a "pop-out" search. We also compared counting ability when a set of dots is presented briefly (in healthy individuals, the automatic deployment of attention over space allows a fast estimation of quantity) or for unlimited duration (favoring sequential counting, hence spatiotemporal integration). All patients showed reduced deployment of attention over space (simultanagnosia), resulting in increased visual search times and underestimations of the number of briefly presented dots. Only two patients showed ocular revisiting behavior that caused frequent omissions in visual search and overestimations of the number of dots presented for unlimited duration. The impairment to deploy attention is considered here as a bilateral covert attention deficit. Disorganized ocular exploration appears to be independent and is hypothesized to result from processes maintaining a salience map over time (spatial working memory) and especially across saccades

Combination of attentional and spatial working memory deficits in Bálint-Holmes syndrome

International audienc

Chapter 20 Optic ataxia and Bálint's syndrome: neuropsychological and neurophysiological prospects

International audienc