L'effet des nanoparticules d'oxyde de zinc sur l'activité respiratoire centrale

Les nanoparticules d’oxyde de zinc (ZnO) sont capables de modifier les propriétés bioélectriques cellulaires au niveau d’un seul neurone, mais nul ne sait jusqu’à présent quelle(s) répercussion(s) ces modifications pourraient avoir à une échelle plus globale, celle des réseaux neuronaux et en particulier ceux qui contrôlent les centres respiratoires

Sur la dynamique des langues dans l'est du Soudan

Le bilinguisme est logiquement perçu comme le résultat d'une situation de contacts tantôt violents tantôt pacifiques dont le terme inéluctable serait l'acculturation. Celle-ci est souvent encouragée. Elle est, pour les tenants d'une politique volontariste, désespérément lente. De fait, comme l'a noté Marcel Cohen : « Le latin, importé par la conquête, a mis cinq siècles à éliminer le gaulois. Le latin en train de prendre forme d'ancien français a mis trois siècles à éliminer les langues germ..

Brainstem Steering of Locomotor Activity in the Newborn Rat

International audienceControl of locomotion relies on motor loops conveying modulatory signals between brainstem and spinal motor circuits. We investigated the steering control of the brainstem reticular formation over the spinal locomotor networks using isolated brainstem-spinal cord preparations of male and female neonatal rats. First, we performed patch-clamp recordings of identified reticulospinal cells during episodes of fictive locomotion. This revealed that a spinal ascending phasic modulation of reticulospinal cell activity is already present at birth. Half of the cells exhibited tonic firing during locomotion, while the other half emitted phasic discharges of action potentials phase locked to ongoing activity. We next showed that mimicking the phasic activity of reticulospinal neurons by applying patterned electrical stimulation bilaterally at the ventral caudal medulla level triggered fictive locomotion efficiently. Moreover, the brainstem stimuli-induced locomotor rhythm was entrained in a one-to-one coupling over a range of cycle periods (2-6 s). Additionally, we induced turning like motor outputs by either increasing or decreasing the relative duration of the stimulation trains on one side of the brainstem compared to the other. The ability of the patterned descending command to control the locomotor output depended on the functional integrity of ventral reticulospinal pathways and the involvement of local spinal central pattern generator circuitry. Altogether, this study provides a mechanism by which brainstem reticulospinal neurons relay steering and speed commands to the spinal locomotor networks

Differential antibacterial activity against Pseudomonas aeruginosa by carbon monoxide-releasing molecules.

International audienceAIMS: Carbon monoxide (CO) delivered in a controlled manner to cells and organisms mediates a variety of pharmacological effects to the extent that CO-releasing molecules (CO-RMs) are being developed for therapeutic purposes. Recently, ruthenium-based CO-RMs have been shown to posses important bactericidal activity. Here we assessed the effect of fast CO releasers containing ruthenium (Ru(CO)(3)Cl(glycinate) [CORM-3] and tricarbonyldichlororuthenium(II) dimer [CORM-2]) and a novel slow manganese-based CO releaser ([Me(4)N][Mn(CO)(4)(thioacetate)(2)] [CORM-371]) on O(2) consumption and growth of Pseudomonas aeruginosa (PAO1). We then compared these effects with the action elicited by sodium boranocarbonate (CORM-A1), which lacks a transition metal but liberates CO with a rate similar to CORM-371. RESULTS: CORM-2, CORM-3, and, to a lesser extent, CORM-371 exerted a significant bactericidal effect and decreased O(2) consumption in PAO1 in vitro. The effect appeared to be independent of reactive oxygen species production, but in the case of metal-containing compounds it was prevented by the thiol donor N-acetylcysteine. In contrast, CORM-A1 was bacteriostatic rather than bactericidal in vitro eliciting only a moderate and transient decrease in O(2) consumption. INNOVATION: None of the tested CO-RMs was toxic to murine macrophages or human fibroblasts at the concentration impairing PA01 growth but only ruthenium-containing CO-RMs showed potential therapeutic properties by increasing the survival of mice infected with PA01. CONCLUSION: CO carriers inhibit bacterial growth and O(2) consumption in vitro, but transition metal carbonyls appear more powerful than compounds spontaneously liberating CO. The nature of the metal in CO-RMs also modulates the anti-bacterial effect, with ruthenium-based CO-RMs being efficacious both in vitro and in vivo

Accuracy of MRI Classification Algorithms in a Tertiary Memory Center Clinical Routine Cohort

BACKGROUND:Automated volumetry software (AVS) has recently become widely available to neuroradiologists. MRI volumetry with AVS may support the diagnosis of dementias by identifying regional atrophy. Moreover, automatic classifiers using machine learning techniques have recently emerged as promising approaches to assist diagnosis. However, the performance of both AVS and automatic classifiers has been evaluated mostly in the artificial setting of research datasets.OBJECTIVE:Our aim was to evaluate the performance of two AVS and an automatic classifier in the clinical routine condition of a memory clinic.METHODS:We studied 239 patients with cognitive troubles from a single memory center cohort. Using clinical routine T1-weighted MRI, we evaluated the classification performance of: 1) univariate volumetry using two AVS (volBrain and Neuroreader$^{TM}$); 2) Support Vector Machine (SVM) automatic classifier, using either the AVS volumes (SVM-AVS), or whole gray matter (SVM-WGM); 3) reading by two neuroradiologists. The performance measure was the balanced diagnostic accuracy. The reference standard was consensus diagnosis by three neurologists using clinical, biological (cerebrospinal fluid) and imaging data and following international criteria.RESULTS:Univariate AVS volumetry provided only moderate accuracies (46% to 71% with hippocampal volume). The accuracy improved when using SVM-AVS classifier (52% to 85%), becoming close to that of SVM-WGM (52 to 90%). Visual classification by neuroradiologists ranged between SVM-AVS and SVM-WGM.CONCLUSION:In the routine practice of a memory clinic, the use of volumetric measures provided by AVS yields only moderate accuracy. Automatic classifiers can improve accuracy and could be a useful tool to assist diagnosis