Discontinuation of a randomised controlled trial in general practice due to unsuccessful patient recruitment.

BACKGROUND: A randomised controlled trial (RCT) in general practice, recruiting incident patients with (sub)acute sciatica, was discontinued because of insufficient recruitment. AIM: To describe factors that influenced the recruitment process and ultimately led to discontinuation of this trial, and to enable others to learn from this experience. DESIGN & SETTING: A pragmatic RCT was designed to compare two pain medication prescription strategies for treatment of (sub)acute sciatica in general practice. After 1 year of patient recruitment, the trial was prematurely terminated. METHOD: To analyse the underperforming recruitment, patient information systems of 20 general practices were screened twice a month to search for eligible patients and identify reasons for non-eligibility. Secondly, after study termination, an open question was distributed to the participating GPs for their views on the recruitment process. RESULTS: A total of 116 GPs from 37 general practices collaborated in the trial. Only eight of 234 patients were included after 12 months. The 22 GPs who offered their opinion on the main reasons for unsuccessful recruitment considered that these were the low incidence rate and strict eligibility criteria, a strong patient and/or GP preference, and time constraints. CONCLUSION: For this RCT, multiple factors were related to recruitment problems but it remains unknown which determinants prevailed. As the research question is unanswered but remains relevant, it is recommended that GPs' daily practice is taken into account when designing an RCT, a pilot study should be performed for feasibility of recruitment, and GP assistants should be involved at an early stage

A Calculation of the Full Neutrino Phase Space in Cold+Hot Dark Matter Models

This paper presents a general-relativistic N-body technique for evolving the phase space distribution of massive neutrinos in linear perturbation theory. The method provides a much more accurate sampling of the neutrino phase space for the HDM initial conditions of N-body simulations in a cold+hot dark matter universe than previous work. Instead of directly sampling the phase space at the end of the linear era, we first compute the evolution of the metric perturbations by numerically integrating the coupled, linearized Einstein, Boltzmann, and fluid equations for all particle species. We then sample the phase space shortly after neutrino decoupling at redshift z=10^9 when the distribution is Fermi-Dirac. To follow the trajectory of each neutrino, we subsequently integrate the geodesic equations for each neutrino in the perturbed background spacetime from z=10^9 to z=13.55, using the linearized metric found in the previous calculation to eliminate discreteness noise. The positions and momenta resulting from this integration represent a fair sample of the full neutrino phase space and can be used as HDM initial conditions for N-body simulations of nonlinear structure evolution in this model. A total of 21 million neutrino particles are used in a 100 Mpc box, with Omega_cdm=0.65, Omega_hdm=0.30, Omega_baryon=0.05, and Hubble constant H_0=50. We find that correlations develop in the neutrino densities and momenta which are absent when only the zeroth-order Fermi-Dirac distribution is considered.Comment: 20 pages, AAS LaTeX v3.0, figures and/or postscript available by anonymous ftp to arcturus.mit.edu, MIT CSR-93-1

Distinct molecular signature of phospholamban p.Arg14del arrhythmogenic cardiomyopathy.

Phospholamban (PLN) p.Arg14del cardiomyopathy is characterized by a distinct arrhythmogenic biventricular phenotype that can be predominantly left ventricular, right ventricular, or both. Our aim was to further elucidate distinct features of this cardiomyopathy with respect to the distribution of desmosomal proteins observed by immunofluorescence (IF) in comparison to desmosomal arrhythmogenic cardiomyopathy and co-existent genetic variants. We studied eight explanted heart specimens from PLN p.Arg14del mutation carriers. Macro- and microscopic examination revealed biventricular presence of fibrofatty replacement and interstitial fibrosis. Five out of 8 (63%) patients met consensus criteria for both arrhythmogenic right ventricular cardiomyopathy (ARVC) and dilated cardiomyopathy (DCM). In four cases, targeted next-generation sequencing revealed one additional pathogenic variant and six variants of unknown significance. IF showed diminished junction plakoglobin signal intensity at the intercalated disks in 4 (67%) out of 6 cases fulfilling ARVC criteria but normal intensity in both cases fulfilling only DCM criteria. Notably, the four cases with diminished junction plakoglobin were also those where an additional gene variant was detected. IF for two proteins recently investigated in desmosomal arrhythmogenic cardiomyopathy (ACM), synapse-associated protein 97 and glycogen synthase kinase-3 beta, showed a distinct distributional pattern in comparison to desmosomal ACM. In 7 (88%) out of 8 cases we observed both a strong synapse-associated protein 97 signal at the sarcomeres and no glycogen synthase kinase-3 beta translocation to the intercalated discs. Phospholamban p.Arg14del cardiomyopathy is characterized by a distinct molecular signature compared to desmosomal ACM, specifically a different desmosomal protein distribution. This study substantiates the idea that additional genetic variants play a role in the phenotypical heterogeneity

Phospholamban immunostaining is a highly sensitive and specific method for diagnosing phospholamban p.Arg14del cardiomyopathy

Phospholamban (PLN) p.Arg14del cardiomyopathy is associated with an increased risk of malignant ventricular arrhythmias and severe heart failure and a poor prognosis from late adolescence. It can be diagnosed in whole heart specimens, but rarely in right ventricular biopsy specimens, by PLN immunohistochemistry showing PLN-containing aggregates concentrated in cardiomyocytes in dense perinuclear aggresomes. The purpose of this study was to determine whether PLN immunohistochemistry can be used to diagnose PLN p.Arg14del cardiomyopathy using apical left ventricular myocardial specimens harvested during left ventricular assist device (LVAD) implantation. At that stage, a genetic diagnosis, which may guide treatment and referral of family members for further investigation, is frequently not established yet. Included were myocardial specimens from 30 diverse genetic cardiomyopathy cases with known variants (9 carriers of the pathogenic PLN p.Arg14del variant, 18 cases with other pathogenic or likely pathogenic variants in cardiomyopathy-related genes, and 3 with only variants of unknown significance). Immunohistochemical analysis revealed typical dense perinuclear globular PLN-positive aggregates, representing aggresomes, in all nine PLN p.Arg14del cases. In 20 non-PLN cases, PLN-staining was absent. In one non-PLN case, one of the two independent observers misinterpreted PLN staining of heavily wrinkled nuclear membranes of cardiomyocytes as perinuclear PLN aggregates. In this genetic cardiomyopathy cohort, PLN Immunohistochemical analysis in LVAD biopsies was found to be a highly sensitive (100%) and specific (95%) method for demonstration of PLN protein aggregates in PLN p.Arg14del cardiomyopathy. In clinical practice, PLN immunohistochemical analysis of LVAD specimens can be of incremental value in the diagnostic workup of this cardiomyopathy, even more so if genetic analysis is not readily available

Effects of food-borne nanomaterials on gastrointestinal tissues and microbiota

Ingestion of engineered nanomaterials is inevitable due to their addition to food and prevalence in food packaging and domestic products such as toothpaste and sun cream. In the absence of robust dosimetry and particokinetic data, it is currently challenging to accurately assess the potential toxicity of food-borne nanomaterials. Herein, we review current understanding of gastrointestinal uptake mechanisms, consider some data on the potential for toxicity of the most commonly encountered classes of food-borne nanomaterials (including TiO2 , SiO2 , ZnO, and Ag nanoparticles), and discuss the potential impact of the luminal environment on nanoparticle properties and toxicity. Much of our current understanding of gastrointestinal nanotoxicology is derived from increasingly sophisticated epithelial models that augment in vivo studies. In addition to considering the direct effects of food-borne nanomaterials on gastrointestinal tissues, including the potential role of chronic nanoparticle exposure in development of inflammatory diseases, we also discuss the potential for food-borne nanomaterials to disturb the normal balance of microbiota within the gastrointestinal tract. The latter possibility warrants close attention given the increasing awareness of the critical role of microbiota in human health and the known impact of some food-borne nanomaterials on bacterial viability. For further resources related to this article, please visit the WIREs website.</p

Exercise does not influence development of phenotype in PLN p.(Arg14del) cardiomyopathy

BACKGROUND: Endurance and frequent exercise are associated with earlier onset of arrhythmogenic right ventricular cardiomyopathy (ARVC) and ventricular arrhythmias (VA) in desmosomal gene variant carriers. Individuals with the pathogenic c.40_42del; p.(Arg14del) variant in the PLN gene are frequently diagnosed with ARVC or dilated cardiomyopathy (DCM). The aim of this study was to evaluate the effect of exercise in PLN p.(Arg14del) carriers. METHODS: In total, 207 adult PLN p.(Arg14del) carriers (39.1% male; mean age 53 ± 15 years) were interviewed on their regular physical activity since the age of 10 years. The association of exercise with diagnosis of ARVC, DCM, sustained VA and hospitalisation for heart failure (HF) was studied. RESULTS: Individuals participated in regular physical activities with a median of 1661 metabolic equivalent of task (MET) hours per year (31.9 MET-hours per week) until clinical presentation. The 50% most and least active individuals had a similar frequency of sustained VA (18.3% vs 18.4%; p = 0.974) and hospitalisation for HF (9.6% vs 8.7%; p = 0.827). There was no relationship between exercise and survival free from (incident) sustained VA (p = 0.65), hospitalisation for HF (p = 0.81), diagnosis of ARVC (p = 0.67) or DCM (p = 0.39) during follow-up. In multivariate analyses, exercise was not associated with sustained VA or HF hospitalisation during follow-up in this relatively not-active cohort. CONCLUSION: There was no association between the amount of exercise and the susceptibility to develop ARVC, DCM, VA or HF in PLN p.(Arg14del) carriers. This suggested unaffected PLN p.(Arg14del) carriers can safely perform mild-moderate exercise, in contrast to desmosomal variant carriers and ARVC patients

Deep neural network-based clustering of deformation curves reveals novel disease features in PLN pathogenic variant carriers

Echocardiographic deformation curves provide detailed information on myocardial function. Deep neural networks (DNNs) may enable automated detection of disease features in deformation curves, and improve the clinical assessment of these curves. We aimed to investigate whether an explainable DNN-based pipeline can be used to detect and visualize disease features in echocardiographic deformation curves of phospholamban (PLN) p.Arg14del variant carriers. A DNN was trained to discriminate PLN variant carriers (n = 278) from control subjects (n = 621) using raw deformation curves obtained by 2D-speckle tracking in the longitudinal axis. A visualization technique was used to identify the parts of these curves that were used by the DNN for classification. The PLN variant carriers were clustered according to the output of the visualization technique. The DNN showed excellent discriminatory performance (C-statistic 0.93 [95% CI 0.87–0.97]). We identified four clusters with PLN-associated disease features in the deformation curves. Two clusters showed previously described features: apical post-systolic shortening and reduced systolic strain. The two other clusters revealed novel features, both reflecting delayed relaxation. Additionally, a fifth cluster was identified containing variant carriers without disease features in the deformation curves, who were classified as controls by the DNN. This latter cluster had a very benign disease course regarding development of ventricular arrhythmias. Applying an explainable DNN-based pipeline to myocardial deformation curves enables automated detection and visualization of disease features. In PLN variant carriers, we discovered novel disease features which may improve individual risk stratification. Applying this approach to other diseases will further expand our knowledge on disease-specific deformation patterns. Graphical abstract: [Figure not available: see fulltext.] Overview of the deep neural network-based pipeline for feature detection in myocardial deformation curves. Firstly, phospholamban (PLN) p.Arg14del variant carriers and controls were selected and a deep neural network (DNN) was trained to detect the PLN variant carriers. Subsequently, a clustering-based approach was performed on the attention maps of the DNN, which revealed 4 distinct phenotypes of PLN variant carriers with different prognoses. Moreover, a cluster without features and a benign prognosis was detected

UNC13A in amyotrophic lateral sclerosis: from genetic association to therapeutic target

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease with limited treatment options and an incompletely understood pathophysiology. Although genomewide association studies (GWAS) have advanced our understanding of the disease, the precise manner in which risk polymorphisms contribute to disease pathogenesis remains unclear. Of relevance, GWAS have shown that a polymorphism (rs12608932) in the UNC13A gene is associated with risk for both ALS and frontotemporal dementia (FTD). Homozygosity for the C-allele at rs12608932 modifies the ALS phenotype, as these patients are more likely to have bulbar-onset disease, cognitive impairment and FTD at baseline as well as shorter survival. UNC13A is expressed in neuronal tissue and is involved in maintaining synaptic active zones, by enabling the priming and docking of synaptic vesicles. In the absence of functional TDP-43, risk variants in UNC13A lead to the inclusion of a cryptic exon in UNC13A messenger RNA, subsequently leading to nonsense mediated decay, with loss of functional protein. Depletion of UNC13A leads to impaired neurotransmission. Recent discoveries have identified UNC13A as a potential target for therapy development in ALS, with a confirmatory trial with lithium carbonate in UNC13A cases now underway and future approaches with antisense oligonucleotides currently under consideration. Considering UNC13A is a potent phenotypic modifier, it may also impact clinical trial outcomes. This present review describes the path from the initial discovery of UNC13A as a risk gene in ALS to the current therapeutic options being explored and how knowledge of its distinct phenotype needs to be taken into account in future trials

Single nucleotide polymorphisms (SNPs) in coding regions of canine dopamine- and serotonin-related genes

<p>Abstract</p> <p>Background</p> <p>Polymorphism in genes of regulating enzymes, transporters and receptors of the neurotransmitters of the central nervous system have been associated with altered behaviour, and single nucleotide polymorphisms (SNPs) represent the most frequent type of genetic variation. The serotonin and dopamine signalling systems have a central influence on different behavioural phenotypes, both of invertebrates and vertebrates, and this study was undertaken in order to explore genetic variation that may be associated with variation in behaviour.</p> <p>Results</p> <p>Single nucleotide polymorphisms in canine genes related to behaviour were identified by individually sequencing eight dogs (<it>Canis familiaris</it>) of different breeds. Eighteen genes from the dopamine and the serotonin systems were screened, revealing 34 SNPs distributed in 14 of the 18 selected genes. A total of 24,895 bp coding sequence was sequenced yielding an average frequency of one SNP per 732 bp (1/732). A total of 11 non-synonymous SNPs (nsSNPs), which may be involved in alteration of protein function, were detected. Of these 11 nsSNPs, six resulted in a substitution of amino acid residue with concomitant change in structural parameters.</p> <p>Conclusion</p> <p>We have identified a number of coding SNPs in behaviour-related genes, several of which change the amino acids of the proteins. Some of the canine SNPs exist in codons that are evolutionary conserved between five compared species, and predictions indicate that they may have a functional effect on the protein. The reported coding SNP frequency of the studied genes falls within the range of SNP frequencies reported earlier in the dog and other mammalian species. Novel SNPs are presented and the results show a significant genetic variation in expressed sequences in this group of genes. The results can contribute to an improved understanding of the genetics of behaviour.</p

Prediction of ventricular arrhythmia in phospholamban p.Arg14del mutation carriers–reaching the frontiers of individual risk prediction

Aims: This study aims to improve risk stratification for primary prevention implantable cardioverter defibrillator (ICD) implantation by developing a new mutation-specific prediction model for malignant ventricular arrhythmia (VA) in phospholamban (PLN) p.Arg14del mutation carriers. The proposed model is compared to an existing PLN risk model. / Methods and results: Data were collected from PLN p.Arg14del mutation carriers with no history of malignant VA at baseline, identified between 2009 and 2020. Malignant VA was defined as sustained VA, appropriate ICD intervention, or (aborted) sudden cardiac death. A prediction model was developed using Cox regression. The study cohort consisted of 679 PLN p.Arg14del mutation carriers, with a minority of index patients (17%) and male sex (43%), and a median age of 42 years [interquartile range (IQR) 27-55]. During a median follow-up of 4.3 years (IQR 1.7-7.4), 72 (10.6%) carriers experienced malignant VA. Significant predictors were left ventricular ejection fraction, premature ventricular contraction count/24 h, amount of negative T waves, and presence of low-voltage electrocardiogram. The multivariable model had an excellent discriminative ability {C-statistic 0.83 [95% confidence interval (CI) 0.78-0.88]}. Applying the existing PLN risk model to the complete cohort yielded a C-statistic of 0.68 (95% CI 0.61-0.75). / Conclusion: This new mutation-specific prediction model for individual VA risk in PLN p.Arg14del mutation carriers is superior to the existing PLN risk model, suggesting that risk prediction using mutation-specific phenotypic features can improve accuracy compared to a more generic approach