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The intracellular Na+ concentration ([Na+]) regulates cardiac contractility. Previous studies have suggested that subsarcolemmal [Na+] is higher than cytosolic [Na+] in cardiac myocytes, but this concept remains controversial. Here, we used electrophysiological experiments and mathematical modeling to test whether there are subsarcolemmal pools with different [Na+] and dynamics compared with the bulk cytosol in rat ventricular myocytes. A Na+ dependency curve for Na+-K+-ATPase (NKA) current was recorded with symmetrical Na+ solutions, i.e., the same [Na+] in the superfusate and internal solution. This curve was used to estimate [Na+] sensed by NKA in other experiments. Three experimental observations suggested that [Na+] is higher near NKA than in the bulk cytosol: 1) when extracellular [Na+] was high, [Na+] sensed by NKA was ~6 mM higher than the internal solution in quiescent cells; 2) long trains of Na+ channel activation almost doubled this gradient; compared with an even intracellular distribution of Na+, the increase of [Na+] sensed by NKA was 10 times higher than expected, suggesting a local Na+ domain; and 3) accumulation of Na+ near NKA after trains of Na+ channel activation dissipated very slowly. Finally, mathematical models assuming heterogeneity of [Na+] between NKA and the Na+ channel better reproduced experimental data than the homogeneous model. In conclusion, our data suggest that NKAsensed [Na+] is higher than [Na+] in the bulk cytosol and that there are differential Na+ pools in the subsarcolemmal space, which could be important for cardiac contractility and arrhythmogenesis. [ABSTRACT FROM AUTHOR]

Single channel dynamics can be modeled using stochastic differential equations, and the dynamics of the state of the channel (e.g. open, closed, inactivated) can be represented using Markov models. Such models can also be used to represent the effect of mutations as well as the effect of drugs used to alleviate deleterious effects of mutations. Based on the Markov model and the stochastic models of the single channel, it is possible to derive deterministic partial differential equations (PDEs) giving the probability density functions (PDFs) of the states of the Markov model. In this study, we have analyzed PDEs modeling wild type (WT) channels, mutant channels (MT) and mutant channels for which a drug has been applied (MTD). Our aim is to show that it is possible to optimize the parameters of a given drug such that the solution of theMTD model is very close to that of the WT: the mutation’s effect is, theoretically, reduced significantly.We will present the mathematical framework underpinning this methodology and apply it to several examples. In particular, we will show that it is possible to use the method to, theoretically, improve the properties of some well-known existing drugs.

Background: People with epilepsy (PWE) and people with intellectual disabilities (ID) both live shorter lives than the general population and both conditions increase the risk of death further. We aimed to measure associations between certain risk factors for death in PWE and ID., Methods: A retrospective case-control study was conducted in ten regions in England and Wales. Data were collected on PWE registered with secondary care ID and neurology services between 2017 and 2021. Prevalence rates of neurodevelopmental, psychiatric and medical diagnoses, seizure frequency, psychotropic and antiseizure medications (ASM) prescribed, and health activity (epilepsy reviews/risk assessments/care plans/compliance etc.) recorded were compared between the two groups., Results: 190 PWE and ID who died were compared with 910 living controls. People who died were less likely to have had an epilepsy risk assessment but had a greater prevalence of genetic conditions, older age, poor physical health, generalized tonic-clonic seizures, polypharmacy (not ASMs) and antipsychotic use. The multivariable logistic regression for risk of epilepsy-related death identified that age over 50, medical condition prevalence, antipsychotic medication use and the lack of an epilepsy review in the last 12 months as associated with increased risk of death. Reviews by psychiatrists in ID services was associated with a 72% reduction in the odds of death compared neurology services., Conclusions: Polypharmacy and use of antipsychotics may be associated with death but not ASMs. Greater and closer monitoring by creating capable health communities may reduce the risk of death. ID services maybe more likely to provide this holistic approach., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany.)

Background: A quarter of people with Intellectual Disability (ID) in the UK have epilepsy compared to 0.6% in the general population and die much younger. Epilepsy is associated with two-fifths of all deaths with related polypharmacy and multi-morbidity. Epilepsy research on this population has been poor. This study describes real-world clinical and risk characteristics of a large cohort across England and Wales., Methods: A retrospective multi-centre cohort study was conducted. Information on seizure characteristics, ID severity, relevant co-morbidities, psychotropic and antiseizure drugs (ASDs), SUDEP and other risk factors was collected across a year., Results: Of 904 adults across 10 centres (male:female, 1.5:1), 320 (35%) had mild ID and 584 (65%) moderate-profound (M/P) ID. The mean age was 39.9 years (SD 15.0). Seizures were more frequent in M/P ID (p < 0.001). Over 50% had physical health co-morbidities, more in mild ID (p < 0.01). A third had psychiatric co-morbidity and a fifth had an underlying genetic disorder. Autism Spectrum Disorder was seen in over a third (37%). Participants were on median two ASDs and overall, five medications. Over quarter were on anti-psychotics. Over 90% had an epilepsy review in the past year but 25% did not have an epilepsy care plan, particularly those with mild ID (p < 0.001). Only 61% had a documented discussion of SUDEP, again less likely with mild ID or their care stakeholders (p < 0.001)., Conclusions: Significant levels of multi-morbidity, polypharmacy and a lack of systemised approach to treatment and risk exist. Addressing these concerns is essential to reduce premature mortality., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany.)

Purpose: To assess state-level variation in changes in uninsurance among Black, Hispanic, and low-income Americans after implementation of the Affordable Care Act (ACA). Methods: We analyzed data from the Behavioral Risk Factor Surveillance System from 2012 to 2016, excluding 2014. For Black, Hispanic, and low-income (<$35,000/year) adults 18-64 years of age, we estimated multivariable regression adjusted pre- (2012-2013) to post-ACA (2015-2016) percentage point changes in uninsurance for each U.S. state. We compared absolute and relative changes and the proportion remaining uninsured post-ACA across states. We also examined whether state-level variation in coverage gains was associated with changes in forgoing needed care due to cost. Results: The range in the percentage point reduction in uninsurance varied substantially across states: 19-fold for Black (0.9-17.4), 18-fold for Hispanic (1.2-21.5), and 23-fold for low-income (1.0-27.8) adults. State-level variation in changes in uninsurance relative to baseline uninsurance rates also varied substantially. In some states, more than one quarter of Black, one half of Hispanic, and approaching one half of low-income adults remained uninsured after full implementation of the ACA. Compared with states in the lowest quintile of change in coverage, states in the highest quintile experienced greater improvements in ability to see a physician. Conclusions: Performance on reducing uninsurance for Black, Hispanic, and low-income Americans under the ACA varied substantially among U.S. states with some making substantial progress and others making little. Post-ACA uninsurance rates remained high for these populations in many states., Competing Interests: No competing financial interests exist., (© Gregory Lines et al., 2021; Published by Mary Ann Liebert, Inc.)

Mutations in presenilin 1 (PSEN1) or presenilin 2 (PSEN2), the catalytic subunit of γ-secretase, cause familial Alzheimer's disease (fAD). We hypothesized that mutations in PSEN1 reduce Notch signaling and alter neurogenesis. Expression data from developmental and adult neurogenesis show relative enrichment of Notch and γ-secretase expression in stem cells, whereas expression of APP and β-secretase is enriched in neurons. We observe premature neurogenesis in fAD iPSCs harboring PSEN1 mutations using two orthogonal systems: cortical differentiation in 2D and cerebral organoid generation in 3D. This is partly driven by reduced Notch signaling. We extend these studies to adult hippocampal neurogenesis in mutation-confirmed postmortem tissue. fAD cases show mutation-specific effects and a trend toward reduced abundance of newborn neurons, supporting a premature aging phenotype. Altogether, these results support altered neurogenesis as a result of fAD mutations and suggest that neural stem cell biology is affected in aging and disease., Competing Interests: Declaration of Interests H.Z. has served at scientific advisory boards for Denali, Roche Diagnostics, Wave, Samumed, Siemens Healthineers, Pinteon Therapeutics, and CogRx; has given lectures in symposia sponsored by Fujirebio, Alzecure, and Biogen; and is a co-founder of Brain Biomarker Solutions in Gothenburg AB (BBS), which is a part of the GU Ventures Incubator Program. The other authors have no conflicts of interest to declare., (Copyright © 2020 The Author(s). Published by Elsevier Inc. All rights reserved.)

Frontotemporal dementia (FTD) describes a group of clinically heterogeneous conditions that frequently affect people under the age of 65 (Le Ber et al., 2013). There are multiple genetic causes of FTD, including coding or splice-site mutations in MAPT, GRN mutations that lead to haploinsufficiency of progranulin protein, and a hexanucleotide GGGGCC repeat expansion in C9ORF72. Pathologically, FTD is characterised by abnormal protein accumulations in neurons and glia. These aggregates can be composed of the microtubule-associated protein tau (observed in FTD with MAPT mutations), the DNA/RNA-binding protein TDP-43 (seen in FTD with mutations in GRN or C9ORF72 repeat expansions) or dipeptide proteins generated by repeat associated non-ATG translation of the C9ORF72 repeat expansion. There are currently no disease-modifying therapies for FTD and the availability of in vitro models that recapitulate pathologies in a disease-relevant cell type would accelerate the development of novel therapeutics. It is now possible to generate patient-specific stem cells through the reprogramming of somatic cells from a patient with a genotype/phenotype of interest into induced pluripotent stem cells (iPSCs). iPSCs can subsequently be differentiated into a plethora of cell types including neurons, astrocytes and microglia. Using this approach has allowed researchers to generate in vitro models of genetic FTD in human cell types that are largely inaccessible during life. In this review we explore the recent progress in the use of iPSCs to model FTD, and consider the merits, limitations and future prospects of this approach., (Crown Copyright © 2020. Published by Elsevier Inc. All rights reserved.)

NOTUM is a carboxylesterase that has been shown to act by mediating the O -depalmitoleoylation of Wnt proteins resulting in suppression of Wnt signaling. Here, we describe the development of NOTUM inhibitors that restore Wnt signaling for use in in vitro disease models where NOTUM over activity is an underlying cause. A crystallographic fragment screen with NOTUM identified 2-phenoxyacetamide 3 as binding in the palmitoleate pocket with modest inhibition activity (IC 50 33 μM). Optimization of hit 3 by SAR studies guided by SBDD identified indazole 38 (IC 50 0.032 μM) and isoquinoline 45 (IC 50 0.085 μM) as potent inhibitors of NOTUM. The binding of 45 to NOTUM was rationalized through an X-ray co-crystal structure determination which showed a flipped binding orientation compared to 3 . However, it was not possible to combine NOTUM inhibition activity with metabolic stability as the majority of the compounds tested were rapidly metabolized in an NADPH-independent manner.

Purpose: Comorbid epilepsy is found in 22.5% of people with intellectual disability (ID). Responding to the continuing lack of clarity to the role of the ID psychiatrist in the United Kingdom with regards to epilepsy care, the Royal College of Psychiatrists (RCPsych) published the College Report (CR) 203 in May 2017. This proposed a three-tiered model of competency in ID epilepsy care, with minimum acceptable standards described as Bronze and greater expertise as Silver and Gold. This article documents the perceptions of ID psychiatrists as to their skills and training needs, and the perceived impact of CR203 on the profession., Methods: An e- questionnaire, matching the standards on CR203 and encouraging comments was designed, reviewed and approved by the RCPsych ID executive faculty. The survey was sent by email to all UK-registered RCPsych ID Faculty members via the RCPsych communications., Results: Of the expected 332 ID psychiatrists in the UK, 141 responses were received (42.4%). Key findings included that ID psychiatrists as a group have an interest in epilepsy but Bronze standards were frequently unmet, with variation across the UK. There was a noted lack of agreement on role among ID psychiatrists again linked to geographical variation. Regional disparity correlated to population density and proximity to tertiary neurological centres., Conclusion: There are significant implications on training, both pre- and post- accreditation for the ID psychiatry speciality. The CR203 standards appear to be steps in the right direction to help define the role ID psychiatrists have in the delivery of epilepsy care., (Copyright © 2018 British Epilepsy Association. Published by Elsevier Ltd. All rights reserved.)

Background: Prophylactic treatment of latent tuberculosis infection (LTBI) is necessary for controlling TB in low-incidence settings. However, treatment is often limited by poor completion rates., Methods: At a community health center serving low-income Hispanics, treatment completion among patients accepting 12 weekly doses of isoniazid (INH) plus rifapentine (RPT) administered as directly observed therapy (DOT) was compared with that among patients accepting nine months of daily self-administered INH during 2012 and 2013 (n=139)., Results: Among patients who agreed to treatment, INH-RPT combination therapy was associated with higher completion rates (OR 3.06; 95% CI, 1.23-7.62; p=.016) when compared to INH only. Overall completion rates were 77.8% (35/45) for INH-RPT combination therapy and 52.1% (49/94) for INH monotherapy., Conclusions: High completion rates for LTBI treatment can be achieved at a community health center using INH-RPT administered via DOT. Greater success treating with INH-RPT may be attributed to DOT strategy and a shorter treatment regimen.

The well-organized contraction of each heartbeat is enabled by an electrical wave traversing and exciting the myocardium in a regular manner. Perturbations to this wave, referred to as arrhythmias, can lead to lethal fibrillation if not treated within minutes. One manner in which arrhythmias originate is an ill-fated interaction of the regular electrical signal controlling the heartbeat, the sinus wave, with an ectopic stimulus. It is not fully understood how and when ectopic waves are generated. Based on mathematical models, we show that ectopic beats can be characterized in terms of unstable eigenmodes of the resting state.

We consider mathematical models of a collection of cardiomyocytes (myocardial tissue) coupled to a varying number of fibroblasts. Our aim is to understand how conductivity (δ) and fibroblast density (η) affect the stability of the collection. We provide mathematical and computational arguments indicating that there is a region of instability in the η-δ space. Mathematical arguments, based on a simplified model of the coupled myocyte-fibroblast system, show that for certain parameter choices, a stationary solution cannot exist. Numerical experiments (1D,2D) are based on a recently developed model of electro-chemical coupling between a human atrial myocyte and a number of associated atrial fibroblasts. The numerical experiments demonstrate that there is a region of instability of the form observed in the simplified model analysis., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Electrokinetic probes based on the differential migration of ternary boronate ester complexes permit the selective analysis of micromolar levels of UV-transparent polyol stereoisomers in urine samples via dynamic complexation-capillary electrophoresis that is applicable to single-step screening of in-born errors of sugar metabolism, such as galactosemia.

Dynamic ligand exchange-affinity capillary electrophoresis (DLE-ACE) is introduced as a convenient platform for assessing the conformational stability and relative affinity of a holoprotein to different ligands without off-line sample pretreatment, since ligand exchange and protein unfolding processes are integrated in-capillary during electromigration.

The non-linear elasticity equations of heart mechanics are solved while emulating the effects of a propagating activation wave. The dynamics of a 1 cm(3) slab of active cardiac tissue was simulated as the electrical wave traversed the muscular heart wall transmurally. The regular Newton (Newton-Raphson) method was compared to two modified Newton approaches, and also to a third approach that delayed update only of some selected Jacobian elements. In addition, the impact of changing the time step (0.01, 0.1 and 1 ms) and the relative non-linear convergence tolerance (10(-4), 10(-3) and 10(-2)) was investigated. Updating the Jacobian only when slow convergence occurred was by far the most efficient approach, giving time savings of 83-96%. For each of the four methods, CPU times were reduced by 48-90% when the time step was increased by a factor 10. Increasing the convergence tolerance by the same factor gave time savings of 3-71%. Different combinations of activation wave speed, stress rate and bulk modulus revealed that the fastest method became relatively even faster as stress rate and bulk modulus was decreased, while the activation speed had negligible influence in this respect.

The electrical activity of the heart may be modeled with a system of partial differential equations (PDEs) known as the bidomain model. Computer simulations based on these equations may become a helpful tool to understand the relationship between changes in the electrical field and various heart diseases. Because of the rapid variations in the electrical field, sufficiently accurate simulations require a fine-scale discretization of the equations. For realistic geometries this leads to a large number of grid points and consequently large linear systems to be solved for each time step. In this paper, we present a fully coupled discretization of the bidomain model, leading to a block structured linear system. We take advantage of the block structure to construct an efficient preconditioner for the linear system, by combining multigrid with an operator splitting technique.

The contraction of the heart is preceded and caused by a cellular electro-chemical reaction, causing an electrical field to be generated. Performing realistic computer simulations of this process involves solving a set of partial differential equations, as well as a large number of ordinary differential equations (ODEs) characterizing the reactive behavior of the cardiac tissue. Experiments have shown that the solution of the ODEs contribute significantly to the total work of a simulation, and there is thus a strong need to utilize efficient solution methods for this part of the problem. This paper presents how an efficient implicit Runge-Kutta method may be adapted to solve a complicated cardiac cell model consisting of 31 ODEs, and how this solver may be coupled to a set of PDE solvers to provide complete simulations of the electrical activity.