L'agent anticonvulsant valproate induit l'expression de la PIMT via la voie de signalisation PI3K/AKT/GSK-3

Les protéines subissent des modifications post-traductionnelles tout au long de leur vieillissement mais aussi dans certains états pathologiques. Parmi ces modifications progressives des protéines, on retrouve notamment la formation des résidus aspartates isomérisés. La protéine L-isoaspartyl méthyltransférase (PIMT) reconnaît et répare des résidus L-isoaspartates anormaux retrouvés dans des protéines. Il a été démontré que la PIMT joue un rôle crucial dans la formation et le maintien du système nerveux central. Ainsi, son fonctionnement s'est avéré important dans le désordre neurologique qu'est l'épilepsie, mais aussi potentiellement dans certaines maladies neurodégénératives comme l'Alzheimer. Notre laboratoire a déjà démontré que l'acide valproïque (VPA), un médicament anticonvulsant, induit l'expression de la PIMT via la voie de signalisation de ERK et également la voie de signalisation glycogènen-synthase-kinase-3 (GSK-3)/β-caténine. Le but de notre recherche a été d'identifier des nouvelles voies de signalisation qui contrôlent l'expression de la PIMT lorsque celle-ci est stimulée par le VPA. Comme modèle cellulaire nous avons utilisé des neuroblastomes SH-SY5Y qui ont été traités avec le VPA pour étudier l'implication de la voie de signalisation phosphatidylinositol 3-kinase (PI3K)/Akt dans l'induction de la PIMT. Nos résultats montrent que lors de l'induction de la PIMT par VPA, la protéine Akt est phosphorylée (Thr 308). De plus, lorsque la protéine PI3K est inhibée par des inhibiteurs pharmacologiques, wortmannin et le LY294002, la phosphorylation de Akt est bloquée et l'induction de la PIMT par VPA est arrêtée. L'inhibition de Akt par un siRNA spécifique produit le même effet. Également, lorsque la voie de signalisation PI3K/Akt est stimulée par le VPA on observe une phosphorylation de la protéine GSK-3 (Ser 21) qui est également observable lorsque les cellules sont traitées avec le lithium, un inhibiteur directe de GSK-3. Finalement, l'inhibition du facteur de transcription CREB avec un siRNA spécifique n'a pas affecté l'induction de la PIMT par VPA. En conclusion, notre étude a démontrée que j'induction de la PIMT par VPA est dépendante de la voie de signalisation PI3K/Akt. L'activation de cette voie de signalisation permet la phosphorylation et donc l'inhibition de la kinase GSK-3, mais l'induction de la PIMT par VPA est indépendante de facteur de transcription CREB. Ces résultats suggèrent plutôt que VPA en inhibant la kinase GSK-3 stabilise la β-caténine permettant ainsi l'expression de la PIMT. \ud ______________________________________________________________________________ \ud MOTS-CLÉS DE L’AUTEUR : PIMT, épilepsie, VPA, PI3K/Ak

Effect of surgical experience and spine subspecialty on the reliability of the {AO} Spine Upper Cervical Injury Classification System

OBJECTIVE The objective of this paper was to determine the interobserver reliability and intraobserver reproducibility of the AO Spine Upper Cervical Injury Classification System based on surgeon experience (< 5 years, 5–10 years, 10–20 years, and > 20 years) and surgical subspecialty (orthopedic spine surgery, neurosurgery, and "other" surgery). METHODS A total of 11,601 assessments of upper cervical spine injuries were evaluated based on the AO Spine Upper Cervical Injury Classification System. Reliability and reproducibility scores were obtained twice, with a 3-week time interval. Descriptive statistics were utilized to examine the percentage of accurately classified injuries, and Pearson’s chi-square or Fisher’s exact test was used to screen for potentially relevant differences between study participants. Kappa coefficients (κ) determined the interobserver reliability and intraobserver reproducibility. RESULTS The intraobserver reproducibility was substantial for surgeon experience level (< 5 years: 0.74 vs 5–10 years: 0.69 vs 10–20 years: 0.69 vs > 20 years: 0.70) and surgical subspecialty (orthopedic spine: 0.71 vs neurosurgery: 0.69 vs other: 0.68). Furthermore, the interobserver reliability was substantial for all surgical experience groups on assessment 1 (< 5 years: 0.67 vs 5–10 years: 0.62 vs 10–20 years: 0.61 vs > 20 years: 0.62), and only surgeons with > 20 years of experience did not have substantial reliability on assessment 2 (< 5 years: 0.62 vs 5–10 years: 0.61 vs 10–20 years: 0.61 vs > 20 years: 0.59). Orthopedic spine surgeons and neurosurgeons had substantial intraobserver reproducibility on both assessment 1 (0.64 vs 0.63) and assessment 2 (0.62 vs 0.63), while other surgeons had moderate reliability on assessment 1 (0.43) and fair reliability on assessment 2 (0.36). CONCLUSIONS The international reliability and reproducibility scores for the AO Spine Upper Cervical Injury Classification System demonstrated substantial intraobserver reproducibility and interobserver reliability regardless of surgical experience and spine subspecialty. These results support the global application of this classification system

Development of an anti-vascular cell adhesion protein-1 aptamer for molecular imaging and inflammation detection in transgenic mouse model of Alzheimer's disease

Cerebrovascular inflammation is often involved in the pathogenesis of neurodegenerative disorders such as Alzheimer's disease (AD). Non-invasive and sensitive molecular imaging of cerebrovascular inflammation biomarkers therefore represents a potential AD diagnostic and therapeutic monitoring method. Here, we describe the development of a novel aptamer-based near infrared fluorescence imaging probe targeting Vascular Cell Adhesion Molecule-1 (VCAM-1), an adhesion molecule overexpressed by the activated cerebrovasculature during inflammation. A SELEX-type screening of a random ssDNA library against human VCAM-1 identified a high-affinity ssDNA aptamer with a dissociation constant of 49 nM. We demonstrated that the Cy5.5-labeled aptamer binds to activated endothelial cells, with no affinity to nonactivated cells. A scrambled aptamer labeled with Cy5.5 did not image activated and non-activated endothelial cells, confirming the sequence specificity of the targeting. In vivo, the aptameric imaging agent targeting VCAM-1 successfully identified inflammation associated with amyloid-\u3b2 plaques deposition in the vessels of the cerebellum of transgenic AD mice. It exhibited excellent retention by remaining bound to vessels 4 hours post-injection, indicating its effectiveness in in vivo imaging and its potential in early detection of cerebrovascular inflammation.Peer reviewed: YesNRC publication: Ye

An international validation of the AO spine subaxial injury classification system

Purpose To validate the AO Spine Subaxial Injury Classification System with participants of various experience levels, subspecialties, and geographic regions. Methods A live webinar was organized in 2020 for validation of the AO Spine Subaxial Injury Classification System. The validation consisted of 41 unique subaxial cervical spine injuries with associated computed tomography scans and key images. Intraobserver reproducibility and interobserver reliability of the AO Spine Subaxial Injury Classification System were calculated for injury morphology, injury subtype, and facet injury. The reliability and reproducibility of the classification system were categorized as slight (? = 0-0.20), fair (? = 0.21-0.40), moderate (? = 0.41-0.60), substantial (? = 0.61-0.80), or excellent (? = > 0.80) as determined by the Landis and Koch classification. Results A total of 203 AO Spine members participated in the AO Spine Subaxial Injury Classification System validation. The percent of participants accurately classifying each injury was over 90% for fracture morphology and fracture subtype on both assessments. The interobserver reliability for fracture morphology was excellent (? = 0.87), while fracture subtype (? = 0.80) and facet injury were substantial (? = 0.74). The intraobserver reproducibility for fracture morphology and subtype were excellent (? = 0.85, 0.88, respectively), while reproducibility for facet injuries was substantial (? = 0.76). Conclusion The AO Spine Subaxial Injury Classification System demonstrated excellent interobserver reliability and intraobserver reproducibility for fracture morphology, substantial reliability and reproducibility for facet injuries, and excellent reproducibility with substantial reliability for injury subtype