Eye and taurine

Taurine is the most abundant amino acid in retina. Although unclear, its role is mainly related to its powerful antioxidant properties. The taurine concentrations in tissues are regulated by an exogenous intake through the nutrition. This taurine intake is highly dependent on the function of taurine transporter. In addition, an endogenous synthesis accounts for the physiological taurine amounts. Previous studies had shown that taurine nutritional deprivation in cat was responsible for severe retinal damages at the photoreceptor layer. By discovering the taurine depletion was incriminated in the retinal toxicity of vigabatrin, we recently demonstrated in different models of retinal degeneration that taurine was involved in the retinal ganglion cells survival. Accordingly, Taurine may play a crucial role in the prevention of retinal degeneration such as retinopathies and glaucomas.La taurine est l’acide aminé le plus abondant dans la rétine. Son rôle, encore mal connu est essentiellement lié à son pouvoir anti-oxydant. Sa concentration tissulaire dépend d’un apport nutritionnel en taurine exogène et du fonctionnement de son transporteur. De plus, une synthèse endogène de taurine participe au maintien de son taux physiologique. D’anciennes études ont montré que la privation nutritionnelle de taurine chez le chat est responsable de dommages rétiniens graves, affectant la couche des photorécepteurs. En découvrant que la toxicité du vigabatrin est liée à une déplétion en taurine, nous avons récemment montré que la taurine participe également à la survie des cellules ganglionnaires rétiniennes dans différents modèles de dégénérescence rétinienne. La taurine pourrait ainsi être impliquée dans la prévention des dégénérescences rétiniennes telles que les rétinopathies et les glaucomes

5-hydroxytryptamine (5-HT)1A autoreceptor adaptive changes in substance P (neurokinin 1) receptor knock-out mice mimic antidepressant-induced desensitization

Antagonists at substance P receptors of the neurokinin 1 (NK1) type have been shown to represent a novel class of antidepressant drugs, with comparable clinical efficacy to the selective serotonin (5-HT) reuptake inhibitors (SSRIs). Because 5-HT 1A receptors may be critically involved in the mechanisms of action of SSRIs, we examined whether these receptors could also be affected in a model of whole-life blockade of NK1 receptors, i.e. knock-out mice lacking the latter receptors (NK1Ϫ/Ϫ). 5-HT 1A receptor labeling by the selective antagonist radioligand receptor agonist ipsapirone to inhibit the discharge of serotoninergic neurons in the dorsal raphe nucleus within brainstem slices, and reduced hypothermic response to 8-OH-DPAT, were noted in NK1Ϫ/Ϫ versus NK1ϩ/ϩ mice. On the other hand, cortical 5-HT overflow caused by systemic injection of the SSRI paroxetine was four-to sixfold higher in freely moving NK1Ϫ/Ϫ mutants than in wild-type NK1ϩ/ϩ mice. Accordingly, the constitutive lack of NK1 receptors appears to be associated with a downregulation/functional desensitization of 5-HT 1A autoreceptors resembling that induced by chronic treatment with SSRI antidepressants. Double immunocytochemical labeling experiments suggest that such a heteroregulation of 5-HT 1A autoreceptors in NK1Ϫ/Ϫ mutants does not reflect the existence of direct NK1-5-HT 1A receptor interactions in normal mice

Potentialités thérapeutiques des neurostéroïdes en psychiatrie

Les neurostéroïdes constituent une famille de molécules synthétisées par le cerveau, représentée par les hormones stéroïdes elles-mêmes, mais également par certains de leurs précurseurs et métabolites. Ils ont des propriétés neuroactives en stimulant des voies de signalisation non génomiques, spécifiques des neurones. Trois types de neurostéroïdes ont été identifiés selon les voies qu’ils activent, à savoir (i) les neurostéroïdes inhibiteurs, (ii) les neurostéroïdes excitateurs et (iii) les neurostéroïdes microtubulaires. Les neurostéroïdes inhibiteurs activent les récepteurs ionotropiques GABA-A, tandis que les neurostéroïdes excitateurs inhibent les courants GABAergiques et stimulent la neurotransmission glutamatergique (soit directement en activant les récepteurs NMDA, soit indirectement via la stimulation des récepteurs sigma-1). Enfin, les neurostéroïdes microtubulaires sont capables de se lier aux protéines associées aux microtubules, comme MAP2, pour favoriser la croissance des microtubules, et in fine la plasticité neuronale. En regard de leurs actions pharmacologiques, certains neurostéroïdes ont fait l’objet d’études cliniques pour le traitement de maladies psychiatriques. C’est le cas de l’alloprégnanolone, le principal neurostéroïde inhibiteur, qui a montré une efficacité dans le traitement de la dépression du post-partum et de l’anxiété. Contrairement à leurs dérivés sulfatés qui n’ont jamais été testés en clinique, la DHEA (déhydroépiandrostérone) et la prégnénolone ont montré des effets antidépresseurs et antipsychotiques. Cependant, la surproduction éventuelle d’hormones provoquée par leur métabolisation a conduit à développer des dérivés de synthèse non métabolisables. C’est le cas du composé MAP4343, un dérivé de la prégnénolone, qui a montré des effets de type antidépresseur dans différents modèles animaux. Il fait actuellement l’objet d’un développement clinique pour le traitement de la dépression

Caractérisation des phénotypes sérotoninergique et corticotrope chez des lignées de souris mutantes considérées comme modèles pour l'étude de la physiopathologie de la dépression

PARIS-BIUSJ-Thèses (751052125) / SudocPARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF

Christelle Dormoy-Rajramanan, Boris Gobille et Erik Neveu (dir.), Mai 68 par celles et ceux qui l’ont vécu

Cinquante ans après les mois de mai et juin 1968, on observe l’engouement que suscite toujours ce moment inattendu de la vie politique française. Aussi n’y a-t-il rien d’étonnant à constater la pléthore de publications qui rendent hommage (ou justice) à l’événement et à ses participants. En revanche, ce qui l’est davantage, c’est de laisser la parole à « celles et ceux » qui ont vécu ce moment historique. Ce défi porté par Christelle Dormoy-Rajramanan, Boris Gobille et Erik Neveu, avec le sou..

Assessing the reliability and consistency of InSAR and GNSS data for retrieving 3D-displacement rapid changes, the example of the 2015 Piton de la Fournaise eruptions

International audienc

InSAR monitoring using RADARSAT-2 data at Piton de la Fournaise (La Reunion) and Karthala (Grande Comore) volcanoes

International audiencePiton de la Fournaise (La Reunion) and Karthala (Grande Comore) are the two active volcanoes of the Southwestern Indian Ocean. A 14 month (April 2013 to June 2014) monitoring period was carried out at both volcanoes using synthetic aperture RADAR interferometry (InSAR) techniques on RADARSAT-2 data. Thanks to the SEAS-OI (Survey of Environment Assisted by Satellite in the Indian Ocean) station, 21 SAR scenes were acquired over this period and InSAR results revealed the slow subsidence of the Dolomieu caldera floor at Piton de la Fournaise, following the 2009 and 2010 eruptions, and the subsidence of the whole cone between April and July 2013. At Karthala no evidence of any volcanic activity was found for the period April 2013 to June 2014. The use of systematic InSAR for volcano monitoring is an efficient tool to study effusive eruptions. We showed that, during periods of unrest, InSAR is able to pick up early signs of a future eruption and monitor secondary phenomena that require no real-time data. During an effusive crisis, it is still difficult to carry out fully operational InSAR monitoring, but using the example of the June 2014 eruption at Piton de la Fournaise, we show that SAR data can help with the detection and tracking of lava flows and active flow paths during effusive eruptions, based on SAR coherence and SAR amplitude. These preliminary results are very promising for the future of InSAR monitoring of active volcanoes and highlight the need for near-real-time access to SAR data in the mapping of active lava flows during effusive eruptions. This study also revealed the major role of ground stations like SEAS-OI in the efficiency of this monitoring, supplying free, near-real-time remote sensing data to the scientific and institutional communities

Posturography in patients with stroke: estimating the percentage of body weight on each foot from a single force platform.

International audienceBACKGROUND AND PURPOSE: Posturography in patients with stroke is widely based on the use of a single force platform and the weightbearing asymmetry quantified from the lateral shift of the center of pressure toward the sound leg. Because the percentage of body weight on each side is a more concrete variable, the present study analyzed the possibility of inferring percentage of body weight from center of pressure. METHODS: Forty-five hemiparetic subjects were asked to stand on a dual platform in a standardized position 3 months after a hemispheric stroke. First, the relationship between the %BW on each foot and the lateral shift of center of pressure was established. Second, the model was tested with a healthy subject standing on a single force platform. RESULTS: The percentage of body weight may be simply modeled from the center of pressure shift, a center of pressure displacement of 10 mm corresponding to a 5% increase in body weight on this side (r=0.97, P<0.001). This linear model is reliable, accurate, and may be generalized to other stand widths. CONCLUSIONS: This finding should be useful for constructors and users of single force platforms, especially those involved in posturographic assessments of asymmetric conditions such as hemiparesis

Volcanic Eruption Monitoring Using Coherence Change Detection Matrix

International audienceThis paper addresses the monitoring of volcanic eruption using a coherence change detection matrix constructed from a multitemporal InSAR image time series. The Piton de la Fournaise volcano (French island, La Reunion), one of the most active volcanoes worldwide, was selected as a case study. Changes on the ground related to eight volcanic eruptions were analyzed through a time series including 49 descending stripmap Sentinel-1 SAR images acquired from January 10, 2018 to August 21, 2019. The experimental results have shown the relevancy of the proposed framework

Contribution of each lower limb to upright standing in stroke patients.

International audienceBACKGROUND AND PURPOSE: To analyze the postural behavior of standing stroke patients: (1) To differentiate between postural impairment attributable to the neurological condition (deficits attributable to the cerebral lesion) and postural impairment attributable to new mechanical constraints caused by body weight asymmetry; (2) To assess the involvement of each limb in the postural impairment; (3) To better understand which clinical deficits underlie the postural impairment. METHODS: The posturographic characteristics of each limb in 41 stroke patients (first hemispheric stroke: 16 left, 25 right cerebral lesions) required to stand in their preferred posture were compared to those in 40 matched healthy individuals required to stand asymmetrically. RESULTS: Compared to normal individuals in a similar asymmetrical posture, stroke patients were more unstable. The weight bearing asymmetry and the lateral postural instability were mainly related to spatial neglect. The paretic limb was unable to bring into play a normal longitudinal pattern of the center of pressure, which reflects an impaired stabilization control. Overall postural instability occurred when the strong limb was unable to compensate for the postural impairment of the paretic limb. CONCLUSIONS: The weight bearing asymmetry of standing stroke patients is not the primary cause of their postural imbalance, which is rather the consequence of impaired control of postural stabilization involving both limbs. Weight bearing asymmetry may not be the principle target of rehabilitation programs aiming at restoring standing balance after stroke. Instead it is suggested that more account should be taken of the compensatory role of the strong limb