An inter-dimer allosteric switch controls NMDA receptor activity.

NMDA receptors (NMDARs) are glutamate-gated ion channels that are key mediators of excitatory neurotransmission and synaptic plasticity throughout the central nervous system. They form massive heterotetrameric complexes endowed with unique allosteric capacity provided by eight extracellular clamshell-like domains arranged as two superimposed layers. Despite an increasing number of full-length NMDAR structures, how these domains cooperate in an intact receptor to control its activity remains poorly understood. Here, combining single-molecule and macroscopic electrophysiological recordings, cysteine biochemistry, and in silico analysis, we identify a rolling motion at a yet unexplored interface between the two constitute dimers in the agonist-binding domain (ABD) layer as a key structural determinant in NMDAR activation and allosteric modulation. This rotation acts as a gating switch that tunes channel opening depending on the conformation of the membrane-distal N-terminal domain (NTD) layer. Remarkably, receptors locked in a rolled state display "super-activity" and resistance to NTD-mediated allosteric modulators. Our work unveils how NMDAR domains move in a concerted manner to transduce long-range conformational changes between layers and command receptor channel activity.

Tripartite split-GFP assay to identify selective intracellular nanobody that suppresses GTPase RHOA subfamily downstream signaling.

Strategies based on intracellular expression of artificial binding domains present several advantages over manipulating nucleic acid expression or the use of small molecule inhibitors. Intracellularly-functional nanobodies can be considered as promising macrodrugs to study key signaling pathways by interfering with protein-protein interactions. With the aim of studying the RAS-related small GTPase RHOA family, we previously isolated, from a synthetic phage display library, nanobodies selective towards the GTP-bound conformation of RHOA subfamily proteins that lack selectivity between the highly conserved RHOA-like and RAC subfamilies of GTPases. To identify RHOA/ROCK pathway inhibitory intracellular nanobodies, we implemented a stringent, subtractive phage display selection towards RHOA-GTP followed by a phenotypic screen based on F-actin fiber loss. Intracellular interaction and intracellular selectivity between RHOA and RAC1 proteins was demonstrated by adapting the sensitive intracellular protein-protein interaction reporter based on the tripartite split-GFP method. This strategy led us to identify a functional intracellular nanobody, hereafter named RH28, that does not cross-react with the close RAC subfamily and blocks/disrupts the RHOA/ROCK signaling pathway in several cell lines without further engineering or functionalization. We confirmed these results by showing, using SPR assays, the high specificity of the RH28 nanobody towards the GTP-bound conformation of RHOA subfamily GTPases. In the metastatic melanoma cell line WM266-4, RH28 expression triggered an elongated cellular phenotype associated with a loss of cellular contraction properties, demonstrating the efficient intracellular blocking of RHOA/B/C proteins downstream interactions without the need of manipulating endogenous gene expression. This work paves the way for future therapeutic strategies based on protein-protein interaction disruption with intracellular antibodies.

GluN2A and GluN2B NMDA receptors use distinct allosteric routes.

Allostery represents a fundamental mechanism of biological regulation that involves long-range communication between distant protein sites. It also provides a powerful framework for novel therapeutics. NMDA receptors (NMDARs), glutamate-gated ionotropic receptors that play central roles in synapse maturation and plasticity, are prototypical allosteric machines harboring large extracellular N-terminal domains (NTDs) that provide allosteric control of key receptor properties with impact on cognition and behavior. It is commonly thought that GluN2A and GluN2B receptors, the two predominant NMDAR subtypes in the adult brain, share similar allosteric transitions. Here, combining functional and structural interrogation, we reveal that GluN2A and GluN2B receptors utilize different long-distance allosteric mechanisms involving distinct subunit-subunit interfaces and molecular rearrangements. NMDARs have thus evolved multiple levels of subunit-specific allosteric control over their transmembrane ion channel pore. Our results uncover an unsuspected diversity in NMDAR molecular mechanisms with important implications for receptor physiology and precision drug development.

Review of the effects of soft robotic gloves for activity-based rehabilitation in individuals with reduced hand function and manual dexterity following a neurological event.

Despite limited scientific evidence, there is an increasing interest in soft robotic gloves to optimize hand- and finger-related functional abilities following a neurological event. This review maps evidence on the effects and effectiveness of soft robotic gloves for hand rehabilitation and, whenever possible, patients' satisfaction. A systematized search of the literature was conducted using keywords structured around three areas: technology attributes, anatomy, and rehabilitation. A total of 272 titles, abstracts, and keywords were initially retrieved, and data were extracted out of 13 articles. Six articles investigated the effects of wearing a soft robotic glove and eight studied the effect or effectiveness of an intervention with it. Some statistically significant and meaningful beneficial effects were confirmed with the 29 outcome measures used. Finally, 11 articles also confirmed users' satisfaction with regard to the soft robotic glove, while some articles also noticed an increased engagement in the rehabilitation program with this technology. Despite the heterogeneity across studies, soft robotic gloves stand out as a safe and promising technology to improve hand- and finger-related dexterity and functional performance. However, strengthened evidence of the effects or effectiveness of such devices is needed before their transition from laboratory to clinical practice.

Anatomy of the White Bear Suppression Inventory (WBSI): a review of previous findings and a new approach.

The White Bear Suppression Inventory (WBSI; Wegner & Zanakos, 1994) was originally designed to assess people's inclination toward thought suppression. In this article, we provide a detailed review of previous findings on the structure of this instrument and present a study that took a new statistical approach. It involved an exploratory factor analysis of the French WBSI using the weighted least squares mean and variance estimator as well as parametric item response theory analyses. Results clearly supported a 2-factor structure with a "suppression" and an "intrusion" dimension. Follow-up regression analyses revealed that intrusion significantly predicted anxiety and depression scores, whereas suppression did not.

Depressive symptoms after trauma: is self-esteem a mediating factor?

Traumatic events have predicted depressive symptoms. Despite this consensus, it remains unclear as to whether the relationship between trauma and depression is consistently mediated by a negative cognitive schema, such as low self-esteem, or whether trauma influences mood independently of low self-esteem. This study tested these relationships while considering depressive symptom types. One hundred thirty-two students reported the number of traumatic events experienced and self-esteem and depression levels. Results indicated 2 depressive symptom types: "cognitive-affective" and "somatic." Structural Equation Modeling tested an unmediated path from trauma to depressive symptoms and a path mediated by self-esteem. Results supported the unmediated relationship between trauma and "cognitive-affective" depressive symptoms, and did not support mediation by self-esteem. Findings are discussed in view of a dimensional rather than categorical approach to depression, and in consideration of alternative symptom clusters resulting from trauma in addition to those captured by posttraumatic stress disorder.

Unmasking GluN1/GluN3A excitatory glycine NMDA receptors.

GluN3A and GluN3B are glycine-binding subunits belonging to the NMDA receptor (NMDAR) family that can assemble with the GluN1 subunit to form unconventional receptors activated by glycine alone. Functional characterization of GluN1/GluN3 NMDARs has been difficult. Here, we uncover two modalities that have transformative properties on GluN1/GluN3A receptors. First, we identify a compound, CGP-78608, which greatly enhances GluN1/GluN3A responses, converting small and rapidly desensitizing currents into large and stable responses. Second, we show that an endogenous GluN3A disulfide bond endows GluN1/GluN3A receptors with distinct redox modulation, profoundly affecting agonist sensitivity and gating kinetics. Under reducing conditions, ambient glycine is sufficient to generate tonic receptor activation. Finally, using CGP-78608 on P8-P12 mouse hippocampal slices, we demonstrate that excitatory glycine GluN1/GluN3A NMDARs are functionally expressed in native neurons, at least in the juvenile brain. Our work opens new perspectives on the exploration of excitatory glycine receptors in brain function and development.

Psychotic symptoms in children and adolescents with 22q11.2 deletion syndrome: Neuropsychological and behavioral implications.

Individuals with 22q11.2 deletion syndrome (22q11DS) are at increased risk for developing schizophrenia: half of affected adolescents report transient psychotic experiences and up to 30% of adults are diagnosed with schizophrenia. Prospective studies have shown that psychotic symptoms in childhood are predictive of later schizophreniform disorders. The current study aimed to define the prevalence and correlates of psychotic symptoms (PS) in young children and adolescents with 22q11DS. Forty-three children and adolescents with 22q11DS (mean age = 10.62+/-11.19) participated in this study. The occurrence of PS and their neuropsychological and behavioral correlates were investigated through semi-structured interviews and standardized measures. Psychotic symptoms were reported in 28% of the total sample and 17% of pre-adolescent children, and associated with decreased verbal IQ scores [F(1) = 4.41, p = 0.042]. Compared to young patients without PS, young patients with PS were perceived by their parents as more anxious-depressed [F(1) = 4.76, p = 0.035] and withdrawn [F(1) = 7.63, p = 0.009], with reduced adaptive socialization skills [F(1) = 6.88, p = 0.012]. Results suggest that psychotic manifestations are present earlier than typically reported in youngsters with 22q11DS and are accompanied by reduced verbal IQ performance and decreased adaptative social skills. The symptomatic, neuropsychological and behavioral characteristics observed in the current study may constitute central markers of increased risk for psychosis in 22q11DS.

Pulse wave velocity testing in the Baltimore longitudinal study of aging.

Carotid-femoral pulse wave velocity is considered the gold standard for measurements of central arterial stiffness obtained through noninvasive methods(1). Subjects are placed in the supine position and allowed to rest quietly for at least 10 min prior to the start of the exam. The proper cuff size is selected and a blood pressure is obtained using an oscillometric device. Once a resting blood pressure has been obtained, pressure waveforms are acquired from the right femoral and right common carotid arteries. The system then automatically calculates the pulse transit time between these two sites (using the carotid artery as a surrogate for the descending aorta). Body surface measurements are used to determine the distance traveled by the pulse wave between the two sampling sites. This distance is then divided by the pulse transit time resulting in the pulse wave velocity. The measurements are performed in triplicate and the average is used for analysis.

Prevalence, clinical correlates, and functional impact of subaortic ventricular septal bulge (from the Baltimore Longitudinal Study of Aging).

A localized hypertrophy of the subaortic segment of the ventricular septum-ventricular septal bulge (VSB)-has been frequently described in series of elderly population, but its prevalence with age, clinical correlates, and impact on cardiac function and exercise capacity remain uncertain. We explored these associations in a cross-sectional sample without known cardiac disease from the Baltimore Longitudinal Study of Aging. We randomly selected 700 participants (50% men, mean age 64 ± 15, range 26 to 95 years) and reviewed their echocardiograms. We identified 28 men and 21 women with VSB (7% overall prevalence). The prevalence of VSB significantly increased with age in both genders (p <0.0001). In multivariate logistic regression including hypertension and other cardiovascular risk factors, only age displayed a significant independent association with VSB (OR 1.06 per year, 95% confidence interval 1.03 to 1.10, p = 0.0001). After multiple adjustments, participants with VSB compared with those without had enhanced global left ventricular contractility (fractional shortening 41 ± 1.3 vs 38 ± 0.3%, p = 0.04; ejection fraction 71 ± 1.6 vs 67 ± 0.4%, p = 0.06; systolic velocity of the mitral annulus 8.4 ± 0.1 vs 8.9 ± 0.3, p = 0.06), and larger aortic root diameters (3.3 ± 0.06 vs 3.1 ± 0.02 cm, p = 0.02). In subgroup of participants who completed a maximal treadmill test (177 women and 196 men), those with VSB (19, 5.1%) had significantly lower peak oxygen consumption than their counterparts (19.6 ± 3.8 vs 22.9 ± 6.6 ml/kg/min, p = 0.03). However, this association was no longer significant after multiple adjustments. In conclusion, the presence of VSB is independently associated with older age and determines enhanced left ventricular contractility, without any evident impact on exercise capacity.

Efectos del peróxido de hidrógeno activado con luz ultravioleta y el peróxido de carbamida en aclaramiento dental / Effect of hydrogen peroxide activated by ultraviolet light and carbamide peroxide in teeth bleaching

Objetivos: Evaluar los efectos en esmalte dental después del tratamiento con PH 25% y PC 16% como sistemas de aclaramiento y posterior aplicación de flúor. Materiales y Métodos: Premolares extraídos distribuidos aleatoriamente en grupos, fueron preservados en suero fisiológico. Se realizaron dos fases con y sin aplicación de flúor post-tratamiento, utilizando Nitewhite ® y Zoom2®, se registró el color al inicio y al final del procedimiento. Las alteraciones en la superficie vestibular de las muestras fueron analizadas en MEB. Resultados: Dentro del total de muestras analizadas, se encontró que el 36.6% mostraron efectos moderados y el 32.9% efectos severos. El análisis de los grupos sin aplicación de flúor, arrojó que los resultados entre las categorías fueron variables. Mientras que en los grupos con aplicación de flúor, predominaron resultados leves. Se encontraron diferencias entre los grupos sin aplicación de Flúor después del aclaramiento (P<0.005). En contraste, entre los grupos con tratamiento posterior de Flúor no hubo diferencias (P= 0.571). Hay diferencias entre los grupos con respecto al efecto en el esmalte, según la prueba de Kruskall Wallis (P<0.005). Con la prueba de la mediana también se concluyó diferencia entre los grupos (P<0.005). Conclusiones: El uso de altas concentraciones de PH en consulta requiere un tiempo limitado en el número de sesiones comparadas con las que el fabricante recomienda, reforzando con un tratamiento casero para obtener mejores resultados y más seguros para el paciente quien reportará menor sensibilidad, siendo indispensable la aplicación de fluor post tratamiento.

Objective: to evaluate dental enamel surface alterations after bleaching treatments with Hydrogen peroxide and Fluoride. Methods: Extracted pre-molars were analys under SEM after bleaching treatment; the samples were storaged in saline solution. Two phases were made, without and with fluoride application after bleaching treatment using Nitewhite® and Zoom2® as bleaching agents, the shade was taken at baseline and after the bleaching procedure. Results: 36.6% of samples showed moderate alterations and 32.9% showed severe enamel alterations. Post/treatment with fluoride showed variable outcomes, but mild alterations in the fluoride/treated samples were found to be more frequent, A statistically significant result was found among fluoride/treated and non/treated groups after bleaching (P<0.005) chisquare test. In contrast, within fluoride/treated groups it was not found significant differences. Conclusions: The use of high concentrated in/office carbamide peroxide may require limited application sessions as recommended by the manufacturer. The use of post/treatment fluoride may bring great benefit to patient’s dental hypersensitivity.