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Monetary cutbacks have occurred in the healthcare industry with increasing incidence since the mid-1980s. Attempts at self-preservation through cost-constraint have been instituted by hospitals, Medicare and Medicaid, and private insurance companies. Curtailment of expenditures, as well as reestablishing profit, has taken many forms. These include managed care, mergers, changing profit status, and aggressive competition. The purpose of this study was to evaluate whether directors of nurse anesthesia programs (NAPs) perceived these items as being detrimental to their NAPs. Data were gathered by descriptive survey design by completing a survey tool. Findings identified directors perceived NAPs at moderate to high risk for closure because of the financial constraints hospitals are experiencing as a result of healthcare reimbursement cutbacks. We found it interesting that many directors were either unaware or considered the hospitals' financial burdens as not impacting their NAP. However, directors who had taken courses or seminars with a focus on issues affecting the financing and reimbursement of healthcare institutions perceived significantly greater risk than those who did not. Potential learning opportunities and strategies to ameliorate risk were identified. Additional education may provide the knowledge and insight to find alternatives to risk, develop strategies, and promote more successful and stable nurse anesthesia educational programs. [ABSTRACT FROM AUTHOR]

Genetic variants in the genes GRIN1, GRIN2A, GRIN2B, and GRIN2D, which encode subunits of the N-methyl-D-aspartate receptor (NMDAR), have been associated with severe and heterogeneous neurologic and neurodevelopmental disorders, including early onset epilepsy, developmental and epileptic encephalopathy, intellectual disability, and autism spectrum disorders. Missense variants in these genes can result in gain or loss of the NMDAR function, requiring opposite therapeutic treatments. Computational methods that predict pathogenicity and molecular functional effects of missense variants are therefore crucial for therapeutic applications. We assembled 223 missense variants from patients, 631 control variants from the general population, and 160 missense variants characterized by electrophysiological readouts that show whether they can enhance or reduce the function of the receptor. This includes new functional data from 33 variants reported here, for the first time. By mapping these variants onto the NMDAR protein structures, we found that pathogenic/benign variants and variants that increase/decrease the channel function were distributed unevenly on the protein structure, with spatial proximity to ligands bound to the agonist and antagonist binding sites being a key predictive feature for both variant pathogenicity and molecular functional consequences. Leveraging distances from ligands, we developed two machine-learning based predictors for NMDA variants: a pathogenicity predictor which outperforms currently available predictors and the first molecular function (increase/decrease) predictor. Our findings can have direct application to patient care by improving diagnostic yield for genetic neurodevelopmental disorders and by guiding personalized treatment informed by the knowledge of the molecular disease mechanism., (© The Author(s) 2024. Published by Oxford University Press.)

Aneurysmal subarachnoid hemorrhage (aSAH) may be associated with cerebral vasospasm, which can lead to delayed cerebral ischemia, infarction, and worsened functional outcomes. The delayed nature of cerebral ischemia secondary to SAH-related vasculopathy presents a window of opportunity for the evaluation of well-tolerated neuroprotective agents administered soon after ictus. Secondary ischemic injury in SAH is associated with increased extracellular glutamate, which can overactivate NMDA receptors (NMDARs), thereby triggering NMDAR-mediated cellular damage. In this study, we have evaluated the effect of the pH-sensitive GluN2B-selective NMDAR inhibitor, NP10679, on neurologic impairment after SAH. This compound demonstrates a selective increase in potency at the acidic extracellular pH levels that occur in the setting of ischemia. We found that NP10679 produced durable improvement of behavioral deficits in a well-characterized murine model of SAH, and these effects were greater than those produced by nimodipine alone, the current standard of care. In addition, we observed an unexpected reduction in SAH-induced luminal narrowing of the middle cerebral artery. Neither nimodipine nor NP10679 alter each other's pharmacokinetic profile, suggesting no obvious drug-drug interactions. Based on allometric scaling of both toxicological and efficacy data, the therapeutic margin in man should be at least 2. These results further demonstrate the utility of pH-dependent neuroprotective agents and GluN2B-selective NMDAR inhibitors as potential therapeutic strategies for the treatment of aSAH. Significance Statement This report describes the properties and utility of the GluN2B-selective pH-sensitive NMDA receptor inhibitor, NP10679, in a well-characterized rodent model of subarachnoid hemorrhage. We show that the administration of NP10679 improves long-term neurological function following subarachnoid hemorrhage, and that in rats there are no drug-drug interactions between NP10679 and nimodipine, the standard of care for this indication., (Copyright © 2024 American Society for Pharmacology and Experimental Therapeutics.)

Past research has evaluated participants' understanding of their memory by soliciting judgments of learning (JOLs). Importantly, JOLs sometimes change memory for the judged material, leading to JOL reactivity . The cue-strengthening account (Soderstrom et al., 2015) and changed-goal account (Mitchum et al., 2016) propose different mechanisms that lead to JOL reactivity. In the present study, we collected measures that can provide further insight into these mechanisms. Specifically, participants studied related and unrelated word pairs in different colored fonts for a source recognition test. Across three experiments, data were analyzed using a hierarchical Bayesian model of multidimensional source memory to determine how JOLs impact item memory as well as relatedness and color source memory. In Experiment 2, we also compared the effects of making JOLs to making judgments of relatedness (JORs), and Experiment 3 examined how JOLs impact study time allocation. The results of our experiments failed to fully follow predictions of either account. Making JOLs (Experiments 1-3) and JORs (Experiment 2) strengthened item memory for related as well as unrelated pairs, the latter finding not predicted by either account. In addition, JOLs and JORs did not specifically strengthen source memory for relatedness, as the cue-strengthening account predicts, nor did JOLs change study time (Experiment 3), as suggested by the changed-goal account. In all, our results provide novel insight that enhanced item memory may be largely responsible for JOL reactivity, thus adjudicating between candidate explanations. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Background: Women of reproductive age experience cyclical variation in the female sex steroid hormones 17β-estradiol and progesterone during the menstrual cycle that is attenuated by some hormonal contraceptives. Estrogens perform a primary function in sexual development and reproduction but have nonreproductive effects on bone, muscle, and sinew tissues (ie, ligaments and tendons), which may influence injury risk and physical performance., Objective: The purpose of the study is to understand the effect of the menstrual cycle and hormonal contraceptive use on bone and calcium metabolism, and musculoskeletal health and performance., Methods: A total of 5 cohorts of physically active women (aged 18-40 years) will be recruited to participate: eumenorrheic, nonhormonal contraceptive users (n=20); combined oral contraceptive pill (COCP) users (n=20); hormonal implant users (n=20); hormonal intrauterine system users (n=20); and hormonal injection users (n=20). Participants must have been using the COCP and implant for at least 1 year and the intrauterine system and injection for at least 2 years. First-void urine samples and fasted blood samples will be collected for biochemical analysis of calcium and bone metabolism, hormones, and metabolic markers. Knee extensor and flexor strength will be measured using an isometric dynamometer, and lower limb tendon and stiffness, tone, and elasticity will be measured using a Myoton device. Functional movement will be assessed using a single-leg drop to assess the frontal plane projection angle and the qualitative assessment of single leg loading. Bone density and macro- and microstructure will be measured using ultrasound, dual-energy x-ray absorptiometry, and high-resolution peripheral quantitative computed tomography. Skeletal material properties will be estimated from reference point indentation, performed on the flat surface of the medial tibia diaphysis. Body composition will be assessed by dual-energy x-ray absorptiometry. The differences in outcome measures between the hormonal contraceptive groups will be analyzed in a one-way between-group analysis of covariance. Within the eumenorrheic group, the influence of the menstrual cycle on outcome measures will be assessed using a linear mixed effects model. Within the COCP group, differences across 2 time points will be analyzed using the paired-samples 2-tailed t test., Results: The research was funded in January 2020, and data collection started in January 2022, with a projected data collection completion date of August 2024. The number of participants who have consented at the point of manuscript submission is 66. It is expected that all data analysis will be completed and results published by the end of 2024., Conclusions: Understanding the effects of the menstrual cycle and hormonal contraception on musculoskeletal health and performance will inform contraceptive choices for physically active women to manage injury risk., Trial Registration: ClinicalTrials.gov NCT05587920; https://classic.clinicaltrials.gov/ct2/show/NCT05587920., International Registered Report Identifier (irrid): DERR1-10.2196/50542., (©Sarah J Myers, Rebecca L Knight, Sophie L Wardle, Kirsty AM Waldock, Thomas J O'Leary, Richard K Jones, Paul E Muckelt, Anton Eisenhauer, Jonathan CY Tang, William D Fraser, Julie P Greeves. Originally published in JMIR Research Protocols (https://www.researchprotocols.org), 11.07.2024.)

Practicing retrieval is a potent learning enhancer. Theoretical accounts of the testing effect generally suggest that the magnitude of the testing effect is dependent on retrieval practice performance, such that conditions that promote better retrieval practice performance should result in a greater testing effect. Empirical evidence, however, has been mixed. Although some studies showed a positive association between retrieval practice performance and the testing effect, others have shown either no relation or the reverse. In the present study, we experimentally manipulated retrieval practice performance using a retrieval-based response deadline manipulation and an encoding-based study trial manipulation. Across six experiments, the magnitude of the testing effect was independent of retrieval practice performance. However, when we aggregated the data across the experiments, participants with superior retrieval practice performance showed a greater testing effect-an individual difference. This dissociation between experimental and correlational outcomes suggests that the positive relation between retrieval practice performance and the testing effect is not causal, and indeed, simulation data showed that the correlation between retrieval practice performance and testing effect was an artifact. We discuss the challenges these findings present to existing accounts of the testing effect. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Given the finding that retrieval practice improves memory, it is frequently suggested that students test themselves while studying. This study examined whether participants benefit from testing if they create and use their own test questions. In Experiment 1, participants read passages, generated questions about the passages, and then either answered their questions as they created them (the procedure used in previous studies) or after a delay. In Experiments 2 and 3, participants either generated questions and answered them after a delay (i.e., self-testing), answered experimenter-provided questions, or reread the passages before taking a final test administered shortly after learning or following a 2-day delay. The experiments found no benefits of answering one's own questions after a delay. In fact, those who self-tested tended to have worse performance on a final assessment of learning than the other learning conditions. Exploratory analyses suggested that participants' questions often did not target material that was on the later criterion test, which may explain why self-testing was not beneficial. The present study suggests that testing may not benefit learning if students create their own test questions. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

N-methyl-D-aspartate receptors (NMDARs) are members of the glutamate receptor family and participate in excitatory postsynaptic transmission throughout the central nervous system. Genetic variants in GRIN genes encoding NMDAR subunits are associated with a spectrum of neurological disorders. The M3 transmembrane helices of the NMDAR couple directly to the agonist-binding domains and form a helical bundle crossing in the closed receptors that occludes the pore. The M3 functions as a transduction element whose conformational change couples ligand binding to opening of an ion conducting pore. In this study, we report the functional consequences of 48 de novo missense variants in GRIN1, GRIN2A, and GRIN2B that alter residues in the M3 transmembrane helix. These de novo variants were identified in children with neurological and neuropsychiatric disorders including epilepsy, developmental delay, intellectual disability, hypotonia and attention deficit hyperactivity disorder. All 48 variants in M3 for which comprehensive testing was completed produce a gain-of-function (28/48) compared to loss-of-function (9/48); 11 variants had an indeterminant phenotype. This supports the idea that a key structural feature of the M3 gate exists to stabilize the closed state so that agonist binding can drive channel opening. Given that most M3 variants enhance channel gating, we assessed the potency of FDA-approved NMDAR channel blockers on these variant receptors. These data provide new insight into the structure-function relationship of the NMDAR gate, and suggest that variants within the M3 transmembrane helix produce a gain-of-function., (© 2024. The Author(s).)

GRID1 and GRID2 encode the enigmatic GluD1 and GluD2 proteins, which form tetrameric receptors that play important roles in synapse organization and development of the central nervous system. Variation in these genes has been implicated in neurodevelopmental phenotypes. We evaluated GRID1 and GRID2 human variants from the literature, ClinVar, and clinical laboratories and found that many of these variants reside in intolerant domains, including the amino terminal domain of both GRID1 and GRID2. Other conserved regions, such as the M3 transmembrane domain, show different intolerance between GRID1 and GRID2. We introduced these variants into GluD1 and GluD2 cDNA and performed electrophysiological and biochemical assays to investigate the mechanisms of dysfunction of GRID1/2 variants. One variant in the GRID1 distal amino terminal domain resides at a position predicted to interact with Cbln2/Cbln4, and the variant disrupts complex formation between GluD1 and Cbln2, which could perturb its role in synapse organization. We also discovered that, like the lurcher mutation (GluD2-A654T), other rare variants in the GRID2 M3 domain create constitutively active receptors that share similar pathogenic phenotypes. We also found that the SCHEMA schizophrenia M3 variant GluD1-A650T produced constitutively active receptors. We tested a variety of compounds for their ability to inhibit constitutive currents of GluD receptor variants and found that pentamidine potently inhibited GluD2-T649A constitutive channels (IC50 50 nM). These results identify regions of intolerance to variation in the GRID genes, illustrate the functional consequences of GRID1 and GRID2 variants, and suggest how these receptors function normally and in disease., (© The Author(s) 2023. Published by Oxford University Press.)

N -methyl-D-aspartate receptors (NMDARs) are crucial for neuronal development and synaptic plasticity. Dysfunction of NMDARs is associated with multiple neurodevelopmental disorders, including epilepsy, autism spectrum disorder, and intellectual disability. Understanding the impact of genetic variants of NMDAR subunits can shed light on the mechanisms of disease. Here, we characterized the functional implications of a de novo mutation of the GluN2A subunit (P1199Rfs*32) resulting in the truncation of the C-terminal domain. The variant was identified in a male patient with epileptic encephalopathy, multiple seizure types, severe aphasia, and neurobehavioral changes. Given the known role of the CTD in NMDAR trafficking, we examined changes in receptor localization and abundance at the postsynaptic membrane using a combination of molecular assays in heterologous cells and rat primary neuronal cultures. We observed that the GluN2A P1199Rfs*32-containing receptors traffic efficiently to the postsynaptic membrane but have increased extra-synaptic expression relative to WT GluN2A-containing NMDARs. Using in silico predictions, we hypothesized that the mutant would lose all PDZ interactions, except for the recycling protein Scribble1. Indeed, we observed impaired binding to the scaffolding protein postsynaptic protein-95 (PSD-95); however, we found the mutant interacts with Scribble1, which facilitates the recycling of both the mutant and the WT GluN2A. Finally, we found that neurons expressing GluN2A P1199Rfs*32 have fewer synapses and decreased spine density, indicating compromised synaptic transmission in these neurons. Overall, our data show that GluN2A P1199Rfs*32 is a loss-of-function variant with altered membrane localization in neurons and provide mechanistic insight into disease etiology., (Copyright © 2024 the authors.)

Competing Interests: The authors declare no conflict of interest.

AMPA receptors are members of the glutamate receptor family and mediate a fast component of excitatory synaptic transmission at virtually all central synapses. Thus, their functional characteristics are a critical determinant of brain function. We evaluate intolerance of each GRIA gene to genetic variation using 3DMTR and report here the functional consequences of 52 missense variants in GRIA1-4 identified in patients with various neurological disorders. These variants produce changes in agonist EC 50 , response time course, desensitization, and/or receptor surface expression. We predict that these functional and localization changes will have important consequences for circuit function, and therefore likely contribute to the patients' clinical phenotype. We evaluated the sensitivity of variant receptors to AMPAR-selective modulators including FDA-approved drugs to explore potential targeted therapeutic options., (© 2023. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Ischemic stroke affects millions of individuals worldwide and a high prevalence of survivors experience cognitive deficits. At present, the underlying mechanisms that drive post-stroke cognitive decline are not well understood. Microglia play a critical role in the post-stroke inflammatory response, but experimental studies show that an accumulation of chronically activated microglia can be harmful and associates with cognitive impairment. This study assessed the effect of acute post-stroke minocycline treatment on chronic microglia and astrocyte expression within the infarct and remote white matter regions, as well as its effect on various domains of cognitive function post-stroke. Nine-month-old male rats received an injection of endothelin-1 into the right dorsal striatum to induce transient focal ischemia, and then were treated with minocycline or saline for 4 days post-stroke. Rats were tested using a series of lever-pressing tasks and the Morris water maze to assess striatal-based learning, cognitive flexibility, and spatial learning and reference memory. We found that minocycline-treated rats had smaller stroke-induced infarcts and less microglia activation in the infarct area and remote white matter regions compared to saline-treated rats at 28 days post-stroke. The behavioural testing results differed according to the cognitive domain; whereas minocycline-treated rats trended towards improved striatal-based learning in a lever-pressing task, but cognitive flexibility was unaffected during the subsequent set-shifting task. Furthermore, minocycline treatment unexpectedly impaired spatial learning, yet it did not alter reference memory. Collectively, we show that post-stroke minocycline treatment can reduce chronic microglia activation even in remote brain regions, with domain-specific effects on cognitive function., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Advances in sequencing technology have generated a large amount of genetic data from patients with neurological conditions. These data have provided diagnosis of many rare diseases, including a number of pathogenic de novo missense variants in GRIN genes encoding N-methyl-d-aspartate receptors (NMDARs). To understand the ramifications for neurons and brain circuits affected by rare patient variants, functional analysis of the variant receptor is necessary in model systems. For NMDARs, this functional analysis needs to assess multiple properties in order to understand how variants could impact receptor function in neurons. One can then use these data to determine whether the overall actions will increase or decrease NMDAR-mediated charge transfer. Here, we describe an analytical and comprehensive framework by which to categorize GRIN variants as either gain-of-function (GoF) or loss-of-function (LoF) and apply this approach to GRIN2B variants identified in patients and the general population. This framework draws on results from six different assays that assess the impact of the variant on NMDAR sensitivity to agonists and endogenous modulators, trafficking to the plasma membrane, response time course and channel open probability. We propose to integrate data from multiple in vitro assays to arrive at a variant classification, and suggest threshold levels that guide confidence. The data supporting GoF and LoF determination are essential to assessing pathogenicity and patient stratification for clinical trials as personalized pharmacological and genetic agents that can enhance or reduce receptor function are advanced. This approach to functional variant classification can generalize to other disorders associated with missense variants., (© The Author(s) 2023. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Background: Mutations in the NMDA receptor are known to disrupt glutamatergic signaling crucial for early neurodevelopment, often leading to severe global developmental delay/intellectual disability, epileptic encephalopathy, and cerebral palsy phenotypes. Both seizures and movement disorders can be highly treatment-refractory., Results: We describe a targeted ABA n-of-1 treatment trial with intrathecal MgSO 4 , rationally designed based on the electrophysiologic properties of this gain of function mutation in the GRIN1 NMDA subunit., Conclusion: Although the invasive nature of the trial necessitated a short-term, non-randomized, unblinded intervention, quantitative longitudinal neurophysiologic monitoring indicated benefit, providing class II evidence in support of intrathecal MgSO 4 for select forms of GRIN disorders., (© 2023. Institut National de la Santé et de la Recherche Médicale (INSERM).)

The short pre-M1 helix within the S1-M1 linker (also referred to as the pre-M1 linker) between the agonist-binding domain (ABD, S1) and the M1 transmembrane helix of the NMDA receptor (NMDAR) is devoid of missense variants within the healthy population but is a locus for de novo pathogenic variants associated with neurological disorders. Several de novo variants within this helix have been identified in patients presenting early in life with intellectual disability, developmental delay, and/or epilepsy. In this study, we evaluated functional properties for twenty variants within the pre-M1 linker in GRIN1, GRIN2A, and GRIN2B genes, including six novel missense variants. The effects of pre-M1 variants on agonist potency, sensitivity to endogenous allosteric modulators, response time course, channel open probability, and surface expression were assessed. Our data indicated that virtually all of the variants evaluated altered channel function, and multiple variants had profound functional consequences, which may contribute to the neurological conditions in the patients harboring the variants in this region. These data strongly suggest that the residues within the pre-M1 helix play a key role in channel gating and are highly intolerant to genetic variation., (© 2023. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Many cases of accidental death associated with drug overdose are due to chronic opioid use, tolerance, and addiction. Analgesic tolerance is characterized by a decreased response to the analgesic effects of opioids, requiring increasingly higher doses to maintain the desired level of pain relief. Overactivation of GluN2B-containing N -methyl-d-Aspartate receptors is thought to play a key role in mechanisms underlying cellular adaptation that takes place in the development of analgesic tolerance. Herein, we describe a novel GluN2B-selective negative allosteric modulator, EU93-108 , that shows high potency and brain penetrance. We describe the structural basis for binding at atomic resolution. This compound possesses intrinsic analgesic properties in the rodent tail immersion test. EU93-108 has an acute and significant anodyne effect, whereby morphine when combined with EU93-108 produces a higher tail flick latency compared to that of morphine alone. These data suggest that engagement of GluN2B as a target has utility in the treatment of pain, and EU93-108 could serve as an appropriate tool compound to interrogate this hypothesis. Future structure-activity relationship work around this scaffold could give rise to compounds that can be co-administered with opioids to diminish the onset of tolerance due to chronic opioid use, thereby modifying their utility.

This study examined the impact of Type 1 Diabetes Mellitus (T1DM) on executive function using a series of operant conditioning-based tasks in rats. Sprague Dawley rats were randomized to either non-diabetic (n = 12; 6 male) or diabetic (n = 14; 6 male) groups. Diabetes was induced using multiple low-dose streptozotocin injections. All diabetic rodents were insulin-treated using subcutaneous insulin pellet implants (9-15 mM). At week 14 of the study, rats were placed on a food restricted diet to induce 5-10 % weight loss. Rodents were familiarized and their set-shifting ability was tested on a series of tasks that required continuous adjustments to novel stimulus-reward paradigms in order to receive food rewards. Results showed no differences in the number of trials, nor number and type of errors made to successfully complete each task between groups. Therefore, we report no differences in executive function, or more specifically set-shifting abilities between non-diabetic and diabetic rodents that receive insulin., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Background: Malformations of cortical development (MCDs) have been reported in a subset of patients with pathogenic heterozygous variants in GRIN1 or GRIN2B , genes which encode for subunits of the N-methyl-D-aspartate receptor (NMDAR). The aim of this study was to further define the phenotypic spectrum of NMDAR-related MCDs., Methods: We report the clinical, radiological and molecular features of 7 new patients and review data on 18 previously reported individuals with NMDAR-related MCDs. Neuropathological findings for two individuals with heterozygous variants in GRIN1 are presented. We report the clinical and neuropathological features of one additional individual with homozygous pathogenic variants in GRIN1 ., Results: Heterozygous variants in GRIN1 and GRIN2B were associated with overlapping severe clinical and imaging features, including global developmental delay, epilepsy, diffuse dysgyria, dysmorphic basal ganglia and hippocampi. Neuropathological examination in two fetuses with heterozygous GRIN1 variants suggests that proliferation as well as radial and tangential neuronal migration are impaired. In addition, we show that neuronal migration is also impaired by homozygous GRIN1 variants in an individual with microcephaly with simplified gyral pattern., Conclusion: These findings expand our understanding of the clinical and imaging features of the 'NMDARopathy' spectrum and contribute to our understanding of the likely underlying pathogenic mechanisms leading to MCD in these patients., Competing Interests: Competing interests: SFT is principal investigator on research grants from Biogen and Janssen to Emory; a member of the Scientific Advisory Board for Eumentis, Sage Therapeutics, GRIN2B Foundation and CureGRIN Foundation; co-founder of NeurOp and Agrithera; and coinventor on Emory-owned intellectual property., (© Author(s) (or their employer(s)) 2023. No commercial re-use. See rights and permissions. Published by BMJ.)

Chronic microglia activation post-stroke is associated with worse neurological and cognitive outcomes. However, measurement of microglia activation in vivo is currently limited. Plasma derived extracellular vesicles (EVs) are cell-specific indicators that may allow for non-invasive measurement of microglia phenotype. The aim of this study was to identify activation-state specific microglia EVs (MEVs) in vitro followed by validation in an experimental stroke model. Following pro-inflammatory activation, MEVs contain the microglia protein TMEM119 alongside increased expression of the Toll-like receptor 4 co-receptor CD14. Immunoprecipitation followed by fluorescent nanoparticle tracking analysis (ONI Nanoimager) was used to confirm the isolation of TMEM119 + /CD14 + EVs from rat plasma. Electron microscopy confirmed that TMEM119 and CD14 localize to the MEV membrane. To model ischemia, plasma was collected from 3-month wildtype Fischer344 rats prior to, 7 and 28 days after endothelin-1 or saline injection into the dorsal right striatum. Fluorescently labelled MEVs were directly measured in the plasma using nanoflow cytometry (Apogee A60 Microplus). We report a significant increase in circulating TMEM119 + /CD14 + EVs 28-days post-stroke in comparison to baseline levels and saline-injected rats, which correlated weakly with stroke volume. TMEM119 + /MHC-II + EVs were also increased post-stroke in comparison to baseline and saline-injected animals. This study is the first to describe an EV biomarker of activated microglia detected directly in plasma following stroke and represents a future tool for the measurement of microglia activity in vivo., (© 2023. The Author(s).)

N-methyl-D-aspartate receptors (NMDARs) play vital roles in normal brain functions (i.e., learning, memory, and neuronal development) and various neuropathological conditions, such as epilepsy, autism, Parkinson's disease, Alzheimer's disease, and traumatic brain injury. Endogenous neuroactive steroids such as 24(S)-hydroxycholesterol (24(S)-HC) have been shown to influence NMDAR activity, and positive allosteric modulators (PAMs) derived from 24(S)-hydroxycholesterol scaffold can also enhance NMDAR function. This study describes the structural determinants and mechanism of action for 24(S)-hydroxycholesterol and two novel synthetic analogs (SGE-550 and SGE-301) on NMDAR function. We also show that these agents can mitigate the altered function caused by a set of loss-of-function missense variants in NMDAR GluN subunit-encoding GRIN genes associated with neurological and neuropsychiatric disorders. We anticipate that the evaluation of novel neuroactive steroid NMDAR PAMs may catalyze the development of new treatment strategies for GRIN-related neuropsychiatric conditions., (© 2023. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

We report on an 8-year-old girl with severe developmental and epileptic encephalopathy due to the compound heterozygous null variants p.(Gln661*) and p.(Leu830Profs*2) in GRIN2A resulting in a knockout of the human GluN2A subunit of the N-methyl-D-aspartate receptor. Both parents had less severe GRIN2A-related phenotypes and were heterozygous carriers of the respective null variant. Functional investigations of both variants suggested a loss-of-function effect. This is the first description of an autosomal recessive, biallelic type of GRIN2A-related disorder. Nonetheless, there are marked parallels to two previously published families with severe epileptic encephalopathy due to homozygous null variants in GRIN1 as well as various knockout animal models. Compared to heterozygous null variants, biallelic knockout of either GluN1 or GluN2A is associated with markedly more severe phenotypes in both humans and mice. Furthermore, recent findings enable a potential precision medicine approach targeting GRIN-related disorders due to null variants., (© 2022 The Authors. Epilepsia published by Wiley Periodicals LLC on behalf of International League Against Epilepsy.)

Cognitive impairment involves complex interactions between multiple pathways and mechanisms, one of which being cardiac disorders. Atrial cardiopathy (AC) is a structural and functional disorder of the left atrium that may be a substrate for other cardiac disorders such as atrial fibrillation (AF) and heart failure (HF). The association between AF and HF and cognitive decline is clear; however, the relationship between AC and cognition requires further investigation. Studies have shown that several markers of AC, such as increased brain natriuretic peptide and left atrial enlargement, are associated with an increased risk for cognitive impairment. The pathophysiology of cognitive decline in patients with AC is not yet well understood. Advancing our understanding of the relationship between AC and cognition may point to important treatable targets and inform future therapeutic advancements. This review presents our current understanding of the diagnosis of AC, as well as clinical characteristics and potential pathways involved in the association between AC and cognitive impairment., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Myers, Jiménez-Ruiz, Sposato and Whitehead.)

N-methyl-D-aspartate receptors (NMDARs) are tetrameric assemblies of two glutamate N-methyl-D-aspartate receptor subunits, GluN1 and two GluN2, that mediate excitatory synaptic transmission in the central nervous system. Four genes ( GRIN2A-D ) encode four distinct GluN2 subunits (GluN2A-D). Thus, NMDARs can be diheteromeric assemblies of two GluN1 plus two identical GluN2 subunits, or triheteromeric assemblies of two GluN1 subunits plus two different GluN2 subunits. An increasing number of de novo GRIN variants have been identified in patients with neurologic conditions and with GRIN2A and GRIN2B harboring the vast majority (> 80%) of variants in these cases. These variants produce a wide range of effects on NMDAR function depending upon its subunit subdomain location and additionally on the subunit composition of diheteromeric versus triheteromeric NMDARs. Increasing evidence implicates triheteromeric GluN1/GluN2A/GluN2B receptors as a major component of the NMDAR pool in the adult cortex and hippocampus. Here, we explore the ability of GluN2A- and GluN2B-selective inhibitors to reduce excess current flow through triheteromeric GluN1/GluN2A/GluN2B receptors that contain one copy of GRIN2A or GRIN2B gain-of-function variants. Our data reveal a broad range of sensitivities for variant-containing triheteromeric receptors to subunit-selective inhibitors, with some variants still showing strong sensitivity to inhibitors, whereas others are relatively insensitive. Most variants, however, retain sensitivity to non-selective channel blockers and the competitive antagonist D-(-)-2-amino-5-phosphonopentanoic acid. These results suggest that with comprehensive analysis, certain disease-related GRIN2A and GRIN2B variants can be identified as potential targets for subunit-selective modulation and potential therapeutic gain. SIGNIFICANCE STATEMENT: Triheteromeric NMDA receptors that contain one copy each of the GluN2A and GluN2B subunits show intermediate sensitivity to GluN2A- and GluN2B-selective inhibitors, making these compounds candidates for attenuating overactive, GRIN variant-containing NMDA receptors associated with neurological conditions. We show that functional evaluation of variant properties with inhibitor pharmacology can support selection of a subset of variants for which GluN2 subunit-selective agents remain effective inhibitors of variant-containing triheteromeric NMDA receptors., (Copyright © 2022 by The American Society for Pharmacology and Experimental Therapeutics.)

Hereditary sensory neuropathy type 1A (HSN1A) is an autosomal, dominantly inherited peripheral neuropathy caused by mutations in serine palmitoyl transferase long chain 1 (SPTLC1), involved in the de novo synthesis of sphingolipids. We have previously reported calcium imbalance, as well as mitochondrial and ER stress in both HSN1 patient lymphoblasts and a transiently transfected cell model. In this study, we investigated the role of the Ca 2+ -activated protease calpain in destabilizing the cell cytoskeleton, by examining calpain activity in SH-SY5Y cells overexpressing the V144D mutant and changes in microtubule-associated proteins (MAP). Intramitochondrial Ca 2+ was found to be significantly depleted and cytoplasmic Ca 2+ increased in the V144D mutant. Subsequently, calpain and proteasome activity were increased and calpain substrates, microtubule associated proteins MAP2, and tau were significantly reduced in the microtubule fraction of the mutant. Significant changes were also found in motor proteins dynein and KIF2A detected in the microtubule fraction of cells overexpressing the V144D mutation. There was also a reduction in anterograde and retrograde mitochondrial transport velocities in the V144D mutant. These findings strongly implicate cytoskeletal aberration caused by Ca 2+ dysregulation and subsequent loss of microtubule transport functions as the cause of axonal dying back that is characteristic of HSN1.

We describe a clinical candidate molecule from a new series of glutamate N -methyl-d-aspartate receptor subunit 2B-selective inhibitors that shows enhanced inhibition at extracellular acidic pH values relative to physiologic pH. This property should render these compounds more effective inhibitors of N -methyl-d-aspartate receptors at synapses responding to a high frequency of action potentials, since glutamate-containing vesicles are acidic within their lumen. In addition, acidification of penumbral regions around ischemic tissue should also enhance selective drug action for improved neuroprotection. The aryl piperazine we describe here shows strong neuroprotective actions with minimal side effects in preclinical studies. The clinical candidate molecule NP10679 has high oral bioavailability with good brain penetration and is suitable for both intravenous and oral dosing for therapeutic use in humans. SIGNIFICANCE STATEMENT: This study identifies a new series of glutamate N -methyl-d-aspartate (NMDA) receptor subunit 2B-selective negative allosteric modulators with properties appropriate for clinical advancement. The compounds are more potent at acidic pH, associated with ischemic tissue, and this property should increase the therapeutic safety of this class by improving efficacy in affected tissue while sparing NMDA receptor block in healthy brain., (Copyright © 2021 by The American Society for Pharmacology and Experimental Therapeutics.)

N -Methyl-D-aspartate receptors (NMDARs) are highly expressed in brain and play important roles in neurodevelopment and various neuropathologic conditions. Here, we describe a new phenotype in an individual associated with a novel de novo deleterious variant in GRIN1 (c.1595C>A, p.Pro532His). The clinical phenotype is characterized with developmental encephalopathy, striking stimulus-sensitive myoclonus, and frontal lobe and frontal white matter hypoplasia, with no apparent seizures detected. NMDARs that contained the P532H within the glycine-binding domain of GluN1 with either the GluN2A or GluN2B subunits were evaluated for changes in their pharmacological and biophysical properties, which surprisingly revealed only modest changes in glycine potency but a significant decrease in glutamate potency, an increase in sensitivity to endogenous zinc inhibition, a decrease in response to maximally effective concentrations of agonists, a shortened synaptic-like response time course, a decreased channel open probability, and a reduced receptor cell surface expression. Molecule dynamics simulations suggested that the variant can lead to additional interactions across the dimer interface in the agonist-binding domains, resulting in a more open GluN2 agonist-binding domain cleft, which was also confirmed by single-molecule fluorescence resonance energy transfer measurements. Based on the functional deficits identified, several positive modulators were evaluated to explore potential rescue pharmacology., Competing Interests: HY is PI on a research grant from Sage Therapeutics to Emory University School of Medicine. ST is PI on research grants from Janssen and Biogen to Emory University School of Medicine, is a member of the SAB for Sage Therapeutics and Eumentis, Inc., is co-founder of NeurOp Inc. and Agrithera Inc., and receives royalties for software. ST and HY are co-inventors on Emory-owned Intellectual Property that includes allosteric modulators of NMDA receptor function. SM owns shares in NeurOp. Inc. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Zhang, Tang, Bhatia, Xu, Paudyal, Liu, Kim, Song, XiangWei, Shaulsky, Myers, Dobyns, Jayaraman, Traynelis, Yuan and Bozarth.)

Test anxiety is a major concern in education because it causes uncomfortable feelings in test-anxious students and may reduce the validity of exam scores as a measure of learning. As such, brief and cost-effective interventions are necessary to minimize the negative impact of test anxiety on students' academic performance. In the present experiment, we examine two such interventions: expressive writing (Experiment 1) and an instructional intervention (Experiment 2), with the latter developed from a similar intervention for stereotype threat. Across four authentic exams in a psychology class, students alternated between completing the intervention and a control task immediately before completing the exams. Neither intervention was effective at reducing test anxiety or improving exam performance. The present results suggest that these interventions may not be successful in addressing the impacts of test anxiety in all classroom settings.

CD4 +  T cells are crucial for effective repression and elimination of cancer cells. Despite a paucity of CD4 +  T cell receptor (TCR) clinical studies, CD4 + T cells are primed to become important therapeutics as they help circumvent tumor antigen escape and guide multifactorial immune responses. However, because CD8 + T cells directly kill tumor cells, most research has focused on the attributes of CD8 + TCRs. Less is known about how TCR affinity and CD4 expression affect CD4 + T cell activation in full length TCR (flTCR) and TCR single chain signaling (TCR-SCS) formats. Here, we generated an affinity panel of TCRs from CD4 + T cells and expressed them in flTCR and three TCR-SCS formats modeled after chimeric antigen receptors (CARs) to understand the contributions of TCR-pMHCII affinity, TCR format, and coreceptor CD4 interactions on CD4 + T cell activation. Strikingly, the coreceptor CD4 inhibited intermediate and high affinity TCR-construct activation by Lck-dependent and -independent mechanisms. These inhibition mechanisms had unique affinity thresholds dependent on the TCR format. Intracellular construct formats affected the tetramer staining for each TCR as well as IL-2 production. IL-2 production was promoted by increased TCR-pMHCII affinity and the flTCR format. Thus, CD4 +  T cell therapy development should consider TCR affinity, CD4 expression, and construct format., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Johnson, Magoffin, Myers, Finnell, Hancock, Orton, Persaud, Christensen and Weber.)

NMDA receptors are ligand-gated ion channels that mediate excitatory neurotransmission. Most native NMDA receptors are tetrameric assemblies of two glycine-binding GluN1 and two glutamate-binding GluN2 subunits. Co-assembly of the glycine-binding GluN1 with glycine-binding GluN3 subunits (GluN3A-B) creates glycine activated receptors that possess strikingly different functional and pharmacological properties compared to GluN1/GluN2 NMDA receptors. The role of GluN1/GluN3 receptors in neuronal function remains unknown, in part due to lack of pharmacological tools with which to explore their physiological roles. We have identified the negative allosteric modulator EU1180-438, which is selective for GluN1/GluN3 receptors over GluN1/GluN2 NMDA receptors, AMPA, and kainate receptors. EU1180-438 is also inactive at GABA, glycine, and P2X receptors, but displays inhibition of some nicotinic acetylcholine receptors. Furthermore, we demonstrate that EU1180-438 produces robust inhibition of glycine-activated current responses mediated by native GluN1/GluN3A receptors in hippocampal CA1 pyramidal neurons. EU1180-438 is a non-competitive antagonist with activity that is independent of membrane potential (i.e. voltage-independent), glycine concentration, and extracellular pH. Non-stationary fluctuation analysis of neuronal current responses provided an estimated weighted mean unitary conductance of 6.1 pS for GluN1/GluN3A channels, and showed that EU1180-438 has no effect on conductance. Site-directed mutagenesis suggests that structural determinants of EU1180-438 activity reside near a short pre-M1 helix that lies parallel to the plane of the membrane below the agonist binding domain. These findings demonstrate that structural differences between GluN3 and other glutamate receptor subunits can be exploited to generate subunit-selective ligands with utility in exploring the roles GluN3 in neuronal function., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Glutamate receptors are essential ligand-gated ion channels in the central nervous system that mediate excitatory synaptic transmission in response to the release of glutamate from presynaptic terminals. The structural and biophysical basis underlying the function of these receptors has been studied for decades by a wide range of approaches. However recent structural, pharmacological and genetic studies have provided new insight into the regions of this protein that are critical determinants of receptor function. Lack of variation in specific areas of the protein amino acid sequences in the human population has defined three regions in each receptor subunit that are under selective pressure, which has focused research efforts and driven new hypotheses. In addition, these three closely positioned elements reside near a cavity that is shown by multiple studies to be a likely site of action for allosteric modulators, one of which is currently in use as an FDA-approved anticonvulsant. These structural elements are capable of controlling gating of the pore, and appear to permit some modulators bound within the cavity to also alter permeation properties. This creates a new precedent whereby features of the channel pore can be modulated by exogenous drugs that bind outside the pore. The convergence of structural, genetic, biophysical and pharmacological approaches is a powerful means to gain insight into the complex biological processes defined by neurotransmitter receptor function., (© 2020 The Authors. The Journal of Physiology © 2020 The Physiological Society.)

Background: Hemizygous mutations in GRIA3 encoding the GluA3 subunit of the amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor are known to be associated with neurodevelopmental disorders, including intellectual disability, hypotonia, an autism spectrum disorder, sleep disturbances, and epilepsy in males., Objective: To describe a new and consistent phenotype in 4 affected male patients associated with an undescribed deleterious variant in GRIA3., Methods: We evaluated a large French family in which segregate a singular phenotype according to an apparent X-linked mode of inheritance. Molecular analyses using next generation sequencing and in vitro functional studies using 2-electrode voltage clamp recordings on Xenopus laevis oocytes and a β-lactamase reporter assay in transfected human embryonic kidney (HEK293) cells were performed., Results: In addition to mild intellectual disability and dysarthria, affected patients presented a tightly consistent early-onset movement disorder combining an exaggerated startle reflex with generalized chorea and multifocal myoclonus. The unreported GRIA3 missense variant c.2477G > A; p.(Gly826Asp) affecting the fourth transmembrane domain of the protein was identified in index patients and their unaffected mothers. Functional studies revealed that variant receptors show decreased current response evoked by agonist (ie, kainic acid and glutamate) and reduced expression on the cell surface in favor of pathogenicity by a loss-of-function mechanism., Conclusions: Taken together, our results suggest that apart from known GRIA3-related disorders, an undescribed mutation-specific singular movement disorder does exist. We thus advocate considering GRIA3 mutations in the differential diagnosis of hyperekplexia and generalized chorea with myoclonus. © 2020 International Parkinson and Movement Disorder Society., (© 2020 International Parkinson and Movement Disorder Society.)

NMDA receptors play crucial roles in excitatory synaptic transmission. Rare variants in GRIN2A encoding the GluN2A subunit are associated with a spectrum of disorders, ranging from mild speech and language delay to intractable neurodevelopmental disorders, including but not limited to developmental and epileptic encephalopathy. A de novo missense variant, p.Ser644Gly, was identified in a child with this disorder, and Grin2a knock-in mice were generated to model and extend understanding of this intractable childhood disease. Homozygous and heterozygous mutant mice exhibited altered hippocampal morphology at 2 weeks of age, and all homozygotes exhibited lethal tonic-clonic seizures by mid-third week. Heterozygous adults displayed susceptibility to induced generalized seizures, hyperactivity, repetitive and reduced anxiety behaviours, plus several unexpected features, including significant resistance to electrically-induced limbic seizures and to pentylenetetrazole induced tonic-clonic seizures. Multielectrode recordings of neuronal networks revealed hyperexcitability and altered bursting and synchronicity. In heterologous cells, mutant receptors had enhanced NMDA receptor agonist potency and slow deactivation following rapid removal of glutamate, as occurs at synapses. NMDA receptor-mediated synaptic currents in heterozygous hippocampal slices also showed a prolonged deactivation time course. Standard anti-epileptic drug monotherapy was ineffective in the patient. Introduction of NMDA receptor antagonists was correlated with a decrease in seizure burden. Chronic treatment of homozygous mouse pups with NMDA receptor antagonists significantly delayed the onset of lethal seizures but did not prevent them. These studies illustrate the power of using multiple experimental modalities to model and test therapies for severe neurodevelopmental disorders, while revealing significant biological complexities associated with GRIN2A developmental and epileptic encephalopathy., (© The Author(s) (2020). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

JOL reactivity refers to the finding that making judgments of learning (JOLs) while studying material influences later memory for that material. Findings of JOL reactivity have been mixed, with some experiments reporting changes to memory when participants make JOLs and others finding no influence of JOLs. Soderstrom, Clark, Halamish, and Bjork (Journal of Experimental Psychology: Learning, Memory, and Cognition, 41(2), 553-558, 2015) proposed that JOL reactivity will only occur if the final test is sensitive to the same cues used to inform JOLs. The current study evaluated this account by manipulating the type of final test. In four experiments, participants studied mixed lists of related and unrelated word pairs and either made JOLs or did not make JOLs. Making JOLs generally enhanced memory for related word pairs when a cued-recall test was administered. However, during free recall, JOLs had no influence on memory for target information, likely because cue-target associations (which are used to inform JOLs) are less beneficial in the absence of cues. JOLs improved item recognition memory for words that were studied in related pairs, although the effect was small. Collectively, data from a meta-analysis of these experiments indicate that JOL reactivity depends on the type of final test, with reactivity most likely to occur when the final test is sensitive to the same cues used to inform JOLs. Future work should continue examining different tests and study materials in order to develop a comprehensive theory of JOL reactivity.

N-methyl-D-aspartate receptors (NMDARs) mediate slow excitatory postsynaptic transmission in the central nervous system, thereby exerting a critical role in neuronal development and brain function. Rare genetic variants in the GRIN genes encoding NMDAR subunits segregated with neurological disorders. Here, we summarize the clinical presentations for 18 patients harboring 12 de novo missense variants in GRIN1, GRIN2A, and GRIN2B that alter residues in the M2 re-entrant loop, a region that lines the pore and is intolerant to missense variation. These de novo variants were identified in children with a set of neurological and neuropsychiatric conditions. Evaluation of the receptor cell surface expression, pharmacological properties, and biophysical characteristics show that these variants can have modest changes in agonist potency, proton inhibition, and surface expression. However, voltage-dependent magnesium inhibition is significantly reduced in all variants. The NMDARs hosting a single copy of a mutant subunit showed a dominant reduction in magnesium inhibition for some variants. These variant NMDARs also show reduced calcium permeability and single-channel conductance, as well as altered open probability. The data suggest that M2 missense variants increase NMDAR charge transfer in addition to varied and complex influences on NMDAR functional properties, which may underlie the patients' phenotypes., (© 2019 Wiley Periodicals, Inc.)

Rapid advances in sequencing technology have led to an explosive increase in the number of genetic variants identified in patients with neurological disease and have also enabled the assembly of a robust database of variants in healthy individuals. A surprising number of variants in the GRIN genes that encode N -methyl-D-aspartate (NMDA) glutamatergic receptor subunits have been found in patients with various neuropsychiatric disorders, including autism spectrum disorders, epilepsy, intellectual disability, attention-deficit/hyperactivity disorder, and schizophrenia. This review compares and contrasts the available information describing the clinical and functional consequences of genetic variations in GRIN2A and GRIN2B. Comparison of clinical phenotypes shows that GRIN2A variants are commonly associated with an epileptic phenotype but that GRIN2B variants are commonly found in patients with neurodevelopmental disorders. These observations emphasize the distinct roles that the gene products serve in circuit function and suggest that functional analysis of GRIN2A and GRIN2B variation may provide insight into the molecular mechanisms, which will allow more accurate subclassification of clinical phenotypes. Furthermore, characterization of the pharmacological properties of variant receptors could provide the first opportunity for translational therapeutic strategies for these GRIN -related neurological and psychiatric disorders., Competing Interests: Competing interests: SFT is PI on a research grant from Allergan and Janssen and Emory University School of Medicine, is a member of the SAB for Sage Therapeutics, is co-founder of NeurOp Inc, and receives royalties for software. SFT and SJM are co-inventors on Emory-owned Intellectual Property that includes allosteric modulators of NMDAR function.No competing interests were disclosed.No competing interests were disclosed., (Copyright: © 2019 Myers SJ et al.)

Cuprizone (CPZ) preferentially affects oligodendrocytes (OLG), resulting in demyelination. To investigate whether central oligodendrocytosis and gliosis triggered an adaptive immune response, the impact of combining a standard (0.2%) or low (0.1%) dose of ingested CPZ with disruption of the blood brain barrier (BBB), using pertussis toxin (PT), was assessed in mice. 0.2% CPZ(±PT) for 5 weeks produced oligodendrocytosis, demyelination and gliosis plus marked splenic atrophy (37%) and reduced levels of CD4 (44%) and CD8 (61%). Conversely, 0.1% CPZ(±PT) produced a similar oligodendrocytosis, demyelination and gliosis but a smaller reduction in splenic CD4 (11%) and CD8 (14%) levels and no splenic atrophy. Long-term feeding of 0.1% CPZ(±PT) for 12 weeks produced similar reductions in CD4 (27%) and CD8 (43%), as well as splenic atrophy (33%), as seen with 0.2% CPZ(±PT) for 5 weeks. Collectively, these results suggest that 0.1% CPZ for 5 weeks may be a more promising model to study the 'inside-out' theory of Multiple Sclerosis (MS). However, neither CD4 nor CD8 were detected in the brain in CPZ±PT groups, indicating that CPZ-mediated suppression of peripheral immune organs is a major impediment to studying the 'inside-out' role of the adaptive immune system in this model over long time periods. Notably, CPZ(±PT)-feeding induced changes in the brain proteome related to the suppression of immune function, cellular metabolism, synaptic function and cellular structure/organization, indicating that demyelinating conditions, such as MS, can be initiated in the absence of adaptive immune system involvement. , Competing Interests: All authors declare no conflict of interest.

N-methyl d-aspartate receptors are ligand-gated ionotropic receptors mediating a slow, calcium-permeable component of excitatory synaptic transmission in the CNS. Variants in genes encoding NMDAR subunits have been associated with a spectrum of neurodevelopmental disorders. Here we report six novel GRIN2D variants and one previously-described disease-associated GRIN2D variant in two patients with developmental and epileptic encephalopathy. GRIN2D encodes for the GluN2D subunit protein; the GluN2D amino acids affected by the variants in this report are located in the pre-M1 helix, transmembrane domain M3, and the intracellular carboxyl terminal domain. Functional analysis in vitro reveals that all six variants decreased receptor surface expression, which may underline some shared clinical symptoms. In addition the GluN2D(Leu670Phe), (Ala675Thr) and (Ala678Asp) substitutions confer significantly enhanced agonist potency, and/or increased channel open probability, while the GluN2D(Ser573Phe), (Ser1271Phe) and (Arg1313Trp) substitutions result in a mild increase of agonist potency, reduced sensitivity to endogenous protons, and decreased channel open probability. The GluN2D(Ser573Phe), (Ala675Thr), and (Ala678Asp) substitutions significantly decrease current amplitude, consistent with reduced surface expression. The GluN2D(Leu670Phe) variant slows current response deactivation time course and increased charge transfer. GluN2D(Ala678Asp) transfection significantly decreased cell viability of rat cultured cortical neurons. In addition, we evaluated a set of FDA-approved NMDAR channel blockers to rescue functional changes of mutant receptors. This work suggests the complexity of the pathological mechanisms of GRIN2D-mediated developmental and epileptic encephalopathy, as well as the potential benefit of precision medicine., (© The Author(s) (2019). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

GluN2B is the most studied subunit of N-methyl-d-aspartate receptors (NMDARs) and implicated in the pathologies of various central nervous system disorders and neurodegenerative diseases. As pan NMDAR antagonists often produce debilitating side effects, new approaches in drug discovery have shifted to subtype-selective NMDAR modulators, especially GluN2B-selective antagonists. While positron emission tomography (PET) studies of GluN2B-selective NMDARs in the living brain would enable target engagement in drug development and improve our understanding in the NMDAR signaling pathways between normal and disease conditions, a suitable PET ligand is yet to be identified. Herein we developed an 18 F-labeled potent antagonist, 2-((1-(4-[ 18 F]fluoro-3-methylphenyl)-1 H-1,2,3-triazol-4-yl)methoxy)-5-methoxypyrimidine ([ 18 F]13; also called [ 18 F]N2B-0518) as a PET tracer for imaging the GluN2B subunit. The radiofluorination of [ 18 F]13 was efficiently achieved by our spirocyclic iodonium ylide (SCIDY) method. In in vitro autoradiography studies, [ 18 F]13 displayed highly region-specific binding in brain sections of rat and nonhuman primate, which was in accordance with the expression of GluN2B subunit. Ex vivo biodistribution in mice revealed that [ 18 F]13 could penetrate the blood-brain barrier with moderate brain uptake (3.60% ID/g at 2 min) and rapid washout. Altogether, this work provides a GluN2B-selective PET tracer bearing a new chemical scaffold and shows high specificity to GluN2B subunit in vitro, which may pave the way for the development of a new generation of GluN2B PET ligands.

Preclinical studies indicate that (2 R ,6 R )-hydroxynorketamine (HNK) is a putative fast-acting antidepressant candidate. Although inhibition of NMDA-type glutamate receptors (NMDARs) is one mechanism proposed to underlie ketamine's antidepressant and adverse effects, the potency of (2 R ,6 R )-HNK to inhibit NMDARs has not been established. We used a multidisciplinary approach to determine the effects of (2 R ,6 R )-HNK on NMDAR function. Antidepressant-relevant behavioral responses and (2 R ,6 R )-HNK levels in the extracellular compartment of the hippocampus were measured following systemic (2 R ,6 R )-HNK administration in mice. The effects of ketamine, (2 R ,6 R )-HNK, and, in some cases, the (2 S ,6 S )-HNK stereoisomer were evaluated on the following: ( i ) NMDA-induced lethality in mice, ( ii ) NMDAR-mediated field excitatory postsynaptic potentials (fEPSPs) in the CA1 field of mouse hippocampal slices, ( iii ) NMDAR-mediated miniature excitatory postsynaptic currents (mEPSCs) and NMDA-evoked currents in CA1 pyramidal neurons of rat hippocampal slices, and ( iv ) recombinant NMDARs expressed in Xenopus oocytes. While a single i.p. injection of 10 mg/kg (2 R ,6 R )-HNK exerted antidepressant-related behavioral and cellular responses in mice, the ED 50 of (2 R ,6 R )-HNK to prevent NMDA-induced lethality was found to be 228 mg/kg, compared with 6.4 mg/kg for ketamine. The 10 mg/kg (2 R ,6 R )-HNK dose generated maximal hippocampal extracellular concentrations of ∼8 µM, which were well below concentrations required to inhibit synaptic and extrasynaptic NMDARs in vitro. (2 S ,6 S )-HNK was more potent than (2 R ,6 R )-HNK, but less potent than ketamine at inhibiting NMDARs. These data demonstrate the stereoselectivity of NMDAR inhibition by (2 R ,6 R ;2 S ,6 S )-HNK and support the conclusion that direct NMDAR inhibition does not contribute to antidepressant-relevant effects of (2 R ,6 R )-HNK., Competing Interests: Conflict of interest statement: T.D.G. has received research funding from Janssen, Roche, and Allergan Pharmaceuticals, and served as a consultant for FSV7 LLC during the preceding 3 years. The authors declare competing financial interests: T.D.G., P.Z., R.M., P.J.M., C.J.T., and C.A.Z. are listed as co-inventors on a patent application for the use of (2R,6R)-hydroxynorketamine and (2S,6S)-hydroxynorketamine in the treatment of depression, anxiety, anhedonia, suicidal ideation, and post-traumatic stress disorders. C.A.Z. and R.M. are listed as co-inventors on a patent for the use of (2R,6R)-hydroxynorketamine, (S)-dehydronorketamine, and other stereoisomeric dehydro- and hydroxylated metabolites of ketamine metabolites in the treatment of depression and neuropathic pain. R.M., P.J.M., C.J.T., and C.A.Z. have assigned patent rights to the US Government but will share a percentage of any royalties that may be received by the Government. P.Z. and T.D.G. have assigned their patent rights to the University of Maryland, Baltimore, but will share a percentage of any royalties that may be received by the University of Maryland, Baltimore. S.F.T. received research support from Janssen, is a consultant for Janssen, is a member of the Scientific Advisory Board for Sage Therapeutics, is a co-founder of NeurOp, Inc., and co-inventor on Emory-owned IP. S.J.M. owns stock in NeurOp, Inc., which is developing NMDAR inhibitors for use in treating neurological disease and disorders. All other authors declare no competing interests.

Background: Eosinophilic esophagitis (EoE) is a chronic TH2-assocated inflammatory condition accompanied by substantial impairments in epithelial barrier function and increased numbers of interleukin 9 (IL-9) expressing inflammatory cells. While IL-9 is known to affect barrier function in the intestine, the functional effects of IL-9 on the esophagus are unclear. Herein we aimed to understand the expression of the IL-9 receptor and effects of IL-9 on the epithelium in EoE., Methods: We used esophageal biopsies from pediatric EoE patients with active and inactive disease to analyze the expression of the IL-9 receptor, the adherens junction protein E-cadherin and the tight junction protein claudin-1. We treated primary human esophageal epithelial cells with IL-9 to understand its effects on E-cadherin expression and function., Results: Active EoE subjects had increased epithelial expression of IL-9 receptor mRNA and protein (P < 0.05) and decreased membrane bound E-cadherin (P < 0.01) and claudin-1 (P < 0.05) expression. IL-9 receptor expression and mislocalized claudin-1 positively correlated and while membrane bound E-cadherin expression negatively correlated with the degree of histologic epithelial remodeling (P < 0.05). IL-9 decreased epithelial resistance in stratified primary human esophageal epithelial cells (P < 0.01) and membrane bound E-cadherin in epithelial cell monolayers (P < 0.01)., Conclusions: These data suggest that IL-9, its receptor, and its effects on E-cadherin may be important mechanisms for epithelial barrier disruption in EoE.