Allergic sensitization impairs lung resident memory CD8 T-cell response and virus clearance.

BACKGROUND: Patients with asthma often suffer from frequent respiratory viral infections and reduced virus clearance. Lung resident memory T cells provide rapid protection against viral reinfections. OBJECTIVE: Because the development of resident memory T cells relies on the lung microenvironment, we investigated the impact of allergen sensitization on the development of virus-specific lung resident memory T cells and viral clearance. METHODS: Mice were sensitized with house dust mite extract followed by priming with X47 and a subsequent secondary influenza infection. Antiviral memory T-cell response and protection to viral infection was assessed before and after secondary influenza infection, respectively. Gene set variation analysis was performed on data sets from the U-BIOPRED asthma cohort using an IFN-γ-induced epithelial cell signature and a tissue resident memory T-cell signature. RESULTS: Viral loads were higher in lungs of sensitized compared with nonsensitized mice after secondary infection, indicating reduced virus clearance. X47 priming induced fewer antiviral lung resident memory CD8 T cells and resulted in lower pulmonary IFN-γ levels in the lungs of sensitized as compared with nonsensitized mice. Using data from the U-BIOPRED cohort, we found that patients with enrichment of epithelial IFN-γ-induced genes in nasal brushings and bronchial biopsies were also enriched in resident memory T-cell-associated genes, had more epithelial CD8 T cells, and reported significantly fewer exacerbations. CONCLUSIONS: The allergen-sensitized lung microenvironment interferes with the formation of antiviral resident memory CD8 T cells in lungs and virus clearance. Defective antiviral memory response might contribute to increased susceptibility of patients with asthma to viral exacerbations.

Discovery of rare variants associated with blood pressure regulation through meta-analysis of 1.3 million individuals.

Genetic studies of blood pressure (BP) to date have mainly analyzed common variants (minor allele frequency > 0.05). In a meta-analysis of up to ~1.3 million participants, we discovered 106 new BP-associated genomic regions and 87 rare (minor allele frequency ≤ 0.01) variant BP associations (P < 5 × 10-8), of which 32 were in new BP-associated loci and 55 were independent BP-associated single-nucleotide variants within known BP-associated regions. Average effects of rare variants (44% coding) were ~8 times larger than common variant effects and indicate potential candidate causal genes at new and known loci (for example, GATA5 and PLCB3). BP-associated variants (including rare and common) were enriched in regions of active chromatin in fetal tissues, potentially linking fetal development with BP regulation in later life. Multivariable Mendelian randomization suggested possible inverse effects of elevated systolic and diastolic BP on large artery stroke. Our study demonstrates the utility of rare-variant analyses for identifying candidate genes and the results highlight potential therapeutic targets.

Multi-ancestry GWAS of the electrocardiographic PR interval identifies 202 loci underlying cardiac conduction.

The electrocardiographic PR interval reflects atrioventricular conduction, and is associated with conduction abnormalities, pacemaker implantation, atrial fibrillation (AF), and cardiovascular mortality. Here we report a multi-ancestry (N = 293,051) genome-wide association meta-analysis for the PR interval, discovering 202 loci of which 141 have not previously been reported. Variants at identified loci increase the percentage of heritability explained, from 33.5% to 62.6%. We observe enrichment for cardiac muscle developmental/contractile and cytoskeletal genes, highlighting key regulation processes for atrioventricular conduction. Additionally, 8 loci not previously reported harbor genes underlying inherited arrhythmic syndromes and/or cardiomyopathies suggesting a role for these genes in cardiovascular pathology in the general population. We show that polygenic predisposition to PR interval duration is an endophenotype for cardiovascular disease, including distal conduction disease, AF, and atrioventricular pre-excitation. These findings advance our understanding of the polygenic basis of cardiac conduction, and the genetic relationship between PR interval duration and cardiovascular disease.

Drug-induced myocardial dysfunction - recommendations for assessment in clinical and pre-clinical studies.

Introduction: Drug-induced myocardial dysfunction is an important safety concern during drug development. Oncology compounds can cause myocardial dysfunction, leading to decreased left ventricular ejection fraction and heart failure via several mechanisms. Cardiovascular imaging has a major role in the early detection and monitoring of cardiotoxicity. Echocardiography is the method of choice because of its widespread availability, low cost, and absence of radiation exposure. Cardiac magnetic resonance imaging can provide better reliability, reproducibility, and accuracy in the detection of drug-induced myocardial dysfunction. In addition, it enables assessment of myocardial edema, fibrosis, and necrosis. Cardiac serologic biomarkers such as troponins and B-type natriuretic peptides are used in combination with imaging during drug development. This article provides a general overview of each imaging modality and practical guidance for early detection and monitoring of cardiotoxicity.Areas covered: Cardiovascular imaging modalities and cardiac biomarkers for monitoring of cardiac function and early detection of drug-induced myocardial dysfunction in drug development.Expert opinion: Some new drugs especially in the oncology field, can cause myocardial dysfunction. Depending on the strength of pre-clinical or clinical data, CV imaging modalities and cardiac biomarkers play an important role in the early detection and mitigation plans for such drugs during their development.

Genetic variants in TRPM7 associated with unexplained stillbirth modify ion channel function.

Stillbirth is the loss of a fetus after 22 weeks of gestation, of which almost half go completely unexplained despite post-mortem. We recently sequenced 35 arrhythmia-associated genes from 70 unexplained stillbirth cases. Our hypothesis was that deleterious mutations in channelopathy genes may have a functional effect in utero that may be pro-arrhythmic in the developing fetus. We observed four heterozygous, nonsynonymous variants in transient receptor potential melastatin 7 (TRPM7), a ubiquitously expressed ion channel known to regulate cardiac development and repolarization in mice. We used site-directed mutagenesis and single-cell patch-clamp to analyze the functional effect of the four stillbirth mutants on TRPM7 ion channel function in heterologous cells. We also used cardiomyocytes derived from human pluripotent stem cells to model the contribution of TRPM7 to action potential morphology. Our results show that two TRPM7 variants, p.G179V and p.T860M, lead to a marked reduction in ion channel conductance. This observation was underpinned by a lack of measurable TRPM7 protein expression, which in the case of p.T860M was due to rapid proteasomal degradation. We also report that human hiPSC-derived cardiomyocytes possess measurable TRPM7 currents; however, siRNA knockdown did not directly affect action potential morphology. TRPM7 variants found in the unexplained stillbirth population adversely affect ion channel function and this may precipitate fatal arrhythmia in utero.

Wetting of binary powder mixtures.

The wetting process involved when a liquid droplet comes into contact with a mixture of particles is a complex phenomenon which is often understood by reference to Cassie-Baxter theory. However, various authors have applied the Cassie-Baxter theory for the prediction of contact angles on two-component mixtures without success. We hypothesise that the main difficulty in applying the Cassie-Baxter theory to mixtures is that if the particles differ in size, it is possible for the small particles to coat the large particles, so reducing the available surface area of the large particles. This leads to the view that bulk volume fractions are not good estimates of surface fractions of the components within the mixture. We argue that the Cassie-Baxter theory over represents the influence of large particles and that below a certain critical volume fraction they exert no influence. We present a simple geometrical model that relates the critical surface coverage volume fraction to the Sauter mean particle size of the binary mixture components. As a consequence, the wetting behaviour can be determined from the bulk volume fractions and the calculated critical surface coverage volume fraction, by means of a simple geometric model. We show that the simple model describes the five two-components systems reported here and a further four systems reported in the literature, irrespective of whether the larger or small particles are hydrophobic/hydrophilic. With this model, it is possible to predict the wetting behaviour of mixtures of particles that coat each other using very simple characterisation methods, so reducing the development time in the creation of formulations in the pharmaceutical industry.

Assessing Particle Segregation Using Near-Infrared Chemical Imaging in Twin Screw Granulation.

In the present study the application of near-infrared chemical imaging (NIR-CI) for assessing particle segregation in granules from continuous twin screw granulation (TSG) granules, were the complex attributes of the machinery configuration in relation to particle segregation is not well understood was investigated. Experiments were performed along the compartmental length of the TSG barrel channel by varying the screw element type and liquid binder viscosity. Examination of the data showed a direct correlation between dispersion due to shear force and de-mixing of particles, which allowed for identification of fundamental granule segregation mechanisms affecting content uniformity in TSG. Particle segregation behavior was linked to dispersion due to shear force through a proposed regime mapping approach which links de-mixing potential to controlling granule formation mechanisms with a new dimensionless mixing number. This was carried out in order to provide a general guideline of how particles segregate along the length of the TSG barrel channel.

Postmortem Genetic Testing for Cardiac Ion Channelopathies in Stillbirths.

BACKGROUND: Although stillbirth is a significant health problem worldwide, the definitive cause of death remains elusive in many cases, despite detailed autopsy. In this study of partly explained and unexplained stillbirths, we used next-generation sequencing to examine an extended panel of 35 candidate genes known to be associated with ion channel disorders and sudden cardiac death. METHODS AND RESULTS: We examined tissue from 242 stillbirths (≥22 weeks), including those where no definite cause of death could be confirmed after a full autopsy. We obtained high-quality DNA from 70 cases, which were then sequenced for a custom panel of 35 genes, 12 for inherited long- and short-QT syndrome genes (LQT1-LQT12 and SQT1-3), and 23 additional candidate genes derived from genome-wide association studies. We examined the functional significance of a selected variant by patch-clamp electrophysiological recording. No predicted damaging variants were identified in KCNQ1 (LQT1) or KCNH2 (LQT2). A rare putative pathogenic variant was found in KCNJ2(LQT7) in 1 case, and several novel variants of uncertain significance were observed. The KCNJ2 variant (p. R40Q), when assessed by whole-cell patch clamp, affected the function of the channel. There was no significant evidence of enrichment of rare predicted damaging variants within any of the candidate genes. CONCLUSIONS: Although a causative link is unclear, 1 putative pathogenic and variants of uncertain significance variant resulting in cardiac channelopathies was identified in some cases of otherwise unexplained stillbirth, and these variants may have a role in fetal demise. CLINICAL TRIAL REGISTRATION: URL: https://www.clinicaltrials.gov. Unique identifier: NCT01120886.

Twin screw wet granulation: Effect of process and formulation variables on powder caking during production.

This work focuses on monitoring the behaviour and the mass of the built up/caking of powder during wet granulation using Twin Screw Granulator (TSG). The variables changed during this work are; powder (α-lactose monohydrate and microcrystalline cellulose (MCC)), the screw configuration (conveying and kneading elements) and the weight percentage of hydroxypropyl-methyl cellulose (HPMC) dissolved in the granulation liquid (i.e. changing liquid viscosity). Additionally, the effect of these variables on the size distribution, of the granules produced, was determined. The experiments were conducted using an acrylic transparent barrel. A stainless steel barrel was then used to conduct the two extreme granulation liquid viscosities with two different screw configurations, using lactose only. This was done to compare the findings to those obtained from the transparent barrel for validation purpose. These variables showed to affect the behaviour and the mass of the powder caking as well as the size distribution of granules. Overall, the use of kneading element resulted in uniform behaviour in caking with higher mass. Furthermore, increasing the amount of HPMC resulted in a reduction of the mass of powder caking for lactose, while showing inconsistent trend for MCC. Furthermore, lactose showed to have a greater tendency to cake in comparison to MCC. The results, for lactose, obtained from the stainless steel barrel compared well with their corresponding conditions from the transparent barrel, as the screw configuration and HPMC mass varied.

Twin screw wet granulation: Binder delivery.

The effects of three ways of binder delivery into the twin screw granulator (TSG) on the residence time, torque, properties of granules (size, shape, strength) and binder distribution were studied. The binder distribution was visualised through the transparent barrel using high speed imaging as well as quantified using offline technique. Furthermore, the effect of binder delivery and the change of screw configuration (conveying elements only and conveying elements with kneading elements) on the surface velocity of granules across the screw channel were investigated using particle image velocimetry (PIV). The binder was delivered in three ways; all solid binder incorporated with powder mixture, 50% of solid binder mixed with powder mixture and 50% mixed with water, all the solid binder dissolved in water. Incorporation of all solid binder with powder mixture resulted in the relatively longer residence time and higher torque, narrower granule size distribution, more spherical granules, weaker big-sized granules, stronger small-sized granules and better binder distribution compared to that in other two ways. The surface velocity of granules showed variation from one screw to another as a result of uneven liquid distribution as well as shown a reduction while introducing the kneading elements into the screw configuration.

Twin screw granulation: steps in granule growth.

The present work focuses on the study of the progression of granules in different compartments along the length of screws in a twin screw granulator (TSG). The effects of varying powder feed rate; liquid to solid ratio and viscosity of granulation liquid on properties of granules was studied. The bigger granules produced at the start of the process were found to change in terms of size, shape and strength along the screw length at all the conditions investigated. The granules became more spherical and their strength increased along the screw length. Tracer granules were also introduced in order to understand the role of kneading and conveying elements in the TSG. The kneading elements promoted consolidation and breakage while the conveying elements led to coalescence, breakage and some consolidation. The results presented here help to provide a qualitative and quantitative understanding of the twin screw granulation process.

Tyrosine-derived 4-hydroxyphenylpyruvate reacts with ketone test fields of 3 commercially available urine dipsticks.

BACKGROUND: The enzyme 4-hydroxyphenylpyruvate dioxygenase (HPPD) is key in tyrosine catabolism. Inhibition of HPPD results in tyrosinemia and increased urinary excretion of 3 phenylketones: 4-hydroxyphenylpyruvate (HPPA), 4-hydroxyphenyllactate (HPLA), and 4-hydroxyphenylacetate (HPAA). A previous study involving administration of a novel HPPD inhibitor to dogs resulted in detection of ketonuria in treated animals using urine dipsticks read by reflectance photometry. Dipstick-positive results were suspected to be false because high concentrations of urinary phenylketones have been reported to react with ketone test fields of urine dipsticks, but visual confirmation was not performed. OBJECTIVE: The purpose of this study was to determine which of the 4- hydroxyphenolic acids produced by HPPD inhibition react with ketone test fields of 3 commercially available urine dipsticks. METHODS: Canine urine samples were prepared with HPPA, HPLA, HPAA, and lithium acetoacetate (positive control) at 6 concentrations. Unmodified urine samples were used as negative controls. All samples were tested for ketones using Combur 10 Test M dipsticks read by a Miditron dipstick analyzer. Urinalysis was also performed by visually inspecting ketone test fields on the Combur 10 Test M, Multistix 10 SG, and Aution 10 EA dipsticks. RESULTS: Urine samples containing HPPA were positive for ketones with Combur 10 Test M dipsticks read by the Miditron analyzer and produced a red­brown color change in ketone test fields of all 3 dipsticks. Urine samples containing HPLA and HPAA were negative by all methods. CONCLUSION: The phenylketone HPPA reacts with ketone test fields of 3 commercially available urine dipsticks, producing a red­brown color change that may be misinterpreted as positive for ketones by reflectance photometry.