A trait-environment relationship approach to participatory plant breeding for organic agriculture

The extent of intraspecific variation in trait-environment relationships is an open question with limited empirical support in crops. In organic agriculture, with high environmental heterogeneity, this knowledge could guide breeding programs to optimize crop attributes. We propose a three-dimensional framework involving crop performance, crop traits, and environmental axes to uncover the multidimensionality of trait-environment relationships within a crop. We modeled instantaneous photosynthesis (A_sat ) and water-use efficiency (WUE) as functions of four phenotypic traits, three soil variables, five carrot (Daucus carota) varieties, and their interactions in a national participatory plant breeding program involving a suite of farms across Canada. We used these interactions to describe the resulting 12 trait-environment relationships across varieties. We found one significant trait-environment relationship for A_sat (taproot tissue density-soil phosphorus), which was consistent across varieties. For WUE, we found that three relationships (petiole diameter-soil nitrogen, petiole diameter-soil phosphorus, and leaf area-soil phosphorus) varied significantly across varieties. As a result, WUE was maximized by different combinations of trait values and soil conditions depending on the variety. Our three-dimensional framework supports the identification of functional traits behind the differential responses of crop varieties to environmental variation and thus guides breeding programs to optimize crop attributes from an eco-evolutionary perspective.

Divergent experiences of U.S. veterans who did and did not complete trauma-focused therapies for PTSD: A national qualitative study of treatment dropout

Prolonged Exposure (PE) and Cognitive Processing Therapy (CPT) are first-line treatments for posttraumatic stress disorder (PTSD) and have been disseminated throughout the U.S. Veterans Health Administration. Treatment non-completion is common and lessens clinical effectiveness; however, prior work has failed to identify factors consistently associated with non-completion. Semi-structured interviews were conducted with a national sample of veterans who recently completed (n = 60) or did not complete (n = 66) PE or CPT. Non-completer interviews focused on factors that contributed to veterans' decisions to drop out and efforts undertaken to complete PE/CPT. Completer interviews focused on challenges faced in completing treatment and facilitators of completion. Transcripts were coded using a mixed deductive/inductive approach; constant comparison was used to identify differences between completers and non-completers. Completers and non-completers differed in the extent of treatment-specific therapist support received, therapists' flexibility in treatment delivery, the type of encouragement offered by the care team and social supports, their interpretation of symptom worsening, the perceived impact of treatment on functioning, and the impact of stressors on their treatment engagement. Treatment-specific therapist support, more patient-centered and flexible treatment delivery, leveraging the full care team, and addressing functional concerns are potential targets for PE and CPT engagement interventions.

Computational modeling identifies the cellular electromechanical effects of disrupted intracellular calcium handling in arrhythmogenic cardiomyopathy patients

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): NWO - ZonMw (VIDI grant 016.176.340 to JL) Dutch Heart Foundation (ERA-CVD JTC2018 grant 2018T094; Dr. Dekker Program grant 2015T082 to JL) The Netherlands Cardio Vascular Research Initiative (CVON): the Dutch Heart Foundation, Dutch Federation of University Medical Center, the Netherlands Organization for Health Research and Development and the Royal Netherlands Academy of Sciences (CVON-eDETECT 2015-12 and CVON-PREDICT2 2018-30 to TvV).

Background

Patients with arrhythmogenic cardiomyopathy (ACM), an inherited progressive cardiac disease, mostly remain asymptomatic until the occurrence of life-threatening arrhythmias. Previous research identified disturbed calcium handling as a potential disease-initiating mechanism [1], but how this translates to arrhythmogenesis and cardiac mechanical dysfunction remains unknown.

Purpose

To characterize disturbed molecular regulators of intracellular calcium (Ca2+) handling in patients with ACM and predict their effects on action potential (AP), calcium transient (CaT) and tension development in both left and right ventricles (LV, RV) using a computer model of cellular electromechanics.

Methods

We performed gene expression (qPCR) and protein level (Western blot) analysis using LV and RV tissue samples obtained from 5 ACM patients who underwent heart transplant and 5 controls with no history of cardiac disease. Changes in protein levels were implemented in our recent human electromechanical cardiomyocyte computer model [2]. CaT, AP and tension traces were simulated and compared to control. Clinical data (age, sex, genetics, ECG, echocardiography) were related to the simulation outcome.

Results

Measured protein levels varied significantly between the 5 patients and between individual LV and RV samples. Exemplary results for one ACM patient are shown in the figure below. In the LV, AP duration was shorter than control (221ms vs. 255ms), CaT peak was increased (0.52µM vs. 0.39µM) but CaT amplitude was reduced due to increased diastolic Ca2+ (0.26µM vs. 0.060µM). Relaxation was also impaired, as shown by a longer CaT and tension duration (965ms vs. 640ms), and an increased diastolic tension (10mN vs. 4.8mN). In the RV, AP duration was shortened, and CaT and tension peak were lower than in the LV (0.37µM and 13.6mN). Diastolic levels were elevated compared to control, and CaT and tension development were prolonged. This can be related to the measured Ca2+ changes: in the LV, a lower activity of the sodium-calcium exchanger (NCX) (22% of control) and SERCA pump (52%) combined with an increased ryanodine receptor (RyR) activity (96%) may impair the extrusion of Ca2+, leading to accumulation of Ca2+ and increased diastolic Ca2+ levels. In the RV, milder changes in NCX (48% of control) and RyR (11%) may explain the larger Ca2+ extrusion, leading to lower CaT peak and diastolic levels. The patient showed a normal LV size, a severely dilated RV, as well as a poor LV fractional shortening suggesting increased ventricular stiffness, in line with the potential impaired relaxation shown by the simulations.

Conclusion

By integrating protein level data from ACM patients into a computational model of cellular electromechanics, we quantified the electromechanical effects of patient-specific Ca2+ handling changes. Future whole-heart extensions of this work have the potential to identify and understand proarrhythmic mechanisms in ACM patients.

Understanding the contribution of stretch-activated ion channels to cardiac arrhythmogenesis using computational modelling

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Dutch heart foundation, ERA-CVD

Introduction

Cardiac electrophysiology and mechanics are strongly interconnected. Among other things, their interaction is mediated by cardiac mechano-electric feedback through stretch-activated ion-channels (SACs). These channels are also thought to contribute to the development of arrhythmias, but their precise role remains unclear.

Purpose

To elucidate the contribution of SACs to arrhythmias using a novel computational model of cardiac electromechanics.

Methods

We implemented two types of SACs in the O’Hara-Rudy model (ORd) of human ventricular electrophysiology: potassium-selective SACs and non-selective SACs (conducting sodium and potassium). The model was calibrated based on experimental human and rodent data of cardiomyocytes undergoing stretch. The calibration also considered inter-species differences, age, and upregulation of SACs under disease conditions. Subsequently, we varied the amplitude, duration, and timing of the simulated stretch to investigate their effects on action potential (AP).

Results

The model reproduced APs measured experimentally. Early afterdepolarizations, delayed afterdepolarizations, and ectopic beats were observed when applying stretch with short duration (e.g. 20ms) and high amplitude (e.g. 40%). When varying the time of application, stretch applied closer to the subsequent beat (cycle length: 1000ms) also shortened the following AP duration (APD) (shortening of 30ms with stretch at t=600ms, 130ms at t=800ms). Higher sensitivity to stretch was observed when simulating disease-related remodelling of SACs. Milder effects (no APD shortening with stretch at t=600ms and t=800ms) were seen with a lower stretch amplitude (e.g. 10% with SACs disease-related remodelling, 15% without). Failure of repolarization only occurred when sustained stretch (1000ms duration) of more than 10% (with SACs disease-related remodelling) or 15% (without) was applied.

Conclusions

Using a novel human electromechanical computational model, we quantified the contribution of SACs to cardiac AP changes. We showed that both disease-related SAC remodelling and variations of amplitude, timing, and duration of cardiomyocyte stretch modulated the effects on cardiac electrophysiology. We also showed that SACs may lead to afterdepolarizations and shorten the subsequent AP duration, factors which may potentially contribute to the generation of arrhythmias.

Mathematically aggregating experts' predictions of possible futures

Structured protocols offer a transparent and systematic way to elicit and combine/aggregate, probabilistic predictions from multiple experts. These judgements can be aggregated behaviourally or mathematically to derive a final group prediction. Mathematical rules (e.g., weighted linear combinations of judgments) provide an objective approach to aggregation. The quality of this aggregation can be defined in terms of accuracy, calibration and informativeness. These measures can be used to compare different aggregation approaches and help decide on which aggregation produces the "best" final prediction. When experts' performance can be scored on similar questions ahead of time, these scores can be translated into performance-based weights, and a performance-based weighted aggregation can then be used. When this is not possible though, several other aggregation methods, informed by measurable proxies for good performance, can be formulated and compared. Here, we develop a suite of aggregation methods, informed by previous experience and the available literature. We differentially weight our experts' estimates by measures of reasoning, engagement, openness to changing their mind, informativeness, prior knowledge, and extremity, asymmetry or granularity of estimates. Next, we investigate the relative performance of these aggregation methods using three datasets. The main goal of this research is to explore how measures of knowledge and behaviour of individuals can be leveraged to produce a better performing combined group judgment. Although the accuracy, calibration, and informativeness of the majority of methods are very similar, a couple of the aggregation methods consistently distinguish themselves as among the best or worst. Moreover, the majority of methods outperform the usual benchmarks provided by the simple average or the median of estimates.

Development of a multiscale electromechanical computer model from cell to hemodynamics

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): CVON eDETECT 2015-12

Background

Patients with genetic cardiomyopathies mostly remain asymptomatic until the occurrence of life-threatening arrhythmias and sudden cardiac death. The responsible pro-arrhythmic mechanisms, as well as the indicators for pro-arrhythmia, often remain unclear. Current research approaches are commonly based on experimental animal models or clinical data obtained from mutation carriers. The translation (and bridging) of results obtained from experimental models to humans and scale integration of these findings remains challenging. As a consequence, clinical relevance is often disputed. In light of these challenges, computer modelling shows strong potential for its ability to capture the complex dynamics of the cardiovascular system across different scales.

Purpose

We therefore aim to develop a multiscale electromechanical computer model coupling electrophysiology, sarcomere dynamics (contractility), whole-heart function and hemodynamics to investigate mechanisms (resulting from genetic predisposition to cardiomyopathy) of arrhythmogenicity and cardiac dysfunction in these patients.

Methods

We coupled our previously published model of cellular electromechanics to the CircAdapt computer model of the heart and circulation. Electromechanical coupling was performed through the amount of calcium bound to troponin (as described in the cellular model). The same electrophysiological properties were assumed in all cardiac walls. Diffusion of calcium from the sarcolemmal space to the membrane was described phenomenologically through a resistance model.

Results

Simulated hemodynamics properties were in range with control values with LVEDV = 110.8mL, LVESV = 38.7mL, RVEDV = 99.2mL, mLAP = 10.2mmHg, mRAP = 4.0mmHg. At the cellular level, sarcolemmal calcium transients showed the effect of mechanical change as illustrated by the bump in CaT. This effect was attenuated at the membrane due to the effect of diffusion. Alterations in the functionality of molecular entities underlying calcium homeostasis recapitulated cellular experimental findings as expected illustrated by implementing changes in adrenergic signaling.

Conclusions

We have established a new multiscale electromechanical computer model describing electrophysiology, sarcomere mechanics and hemodynamics. The model simulates normal values in the control situation. Current work focusses on parameter sensitivity analysis and validation. Feeding this new model with experimentally obtained data from patient-specific models (ranging from individual cells to e.g. transgenic mouse models based on relevant mutations) therefore has potential to bridge the gap between pathogenic experimental models and patient data. This will add to the understanding of underlying mechanisms responsible for disease onset and progression, and furthermore could develop into a tool to identify patients/mutation carriers at risk for severe disease outcome. Abstract Figure.

Arrhythmogenic cardiomyopathy is characterized by apex-to-base heterogeneity of right ventricular myocardial contractility, stiffness, and mechanical delay: a patient-specific modeling study

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): NWO-ZonMw, VIDI grant 016.176.340 Dutch Heart Foundation (2015T082)

Introduction

Arrhythmogenic Cardiomyopathy (AC) is an inherited cardiac disease, characterized by life-threatening ventricular arrhythmias and progressive cardiac dysfunction. Geno-positive subjects with and without symptoms may suffer from sudden cardiac death. Therefore, early disease detection and risk stratification is important. Right ventricular (RV) longitudinal deformation abnormalities in early stages of disease have been shown to be of prognostic value. We propose an imaging-based patient-specific computer modelling approach for non-invasive quantification of regional ventricular tissue abnormalities.

Purpose

To non-invasively reveal the individual patient’s myocardial tissue substrates underlying the regional RV deformation abnormalities in AC mutation carriers.

Methods

In 65 individuals carrying a plakophilin-2 or desmoglein-2 mutation and 20 control subjects, regional longitudinal deformation patterns of the RV free wall (RVfw), interventricular septum (IVS) and left ventricular free wall (LVfw) were obtained using speckle-tracking echocardiography (Figure: left). This cohort was subdivided into 3 consecutive clinical stages i.e. subclinical (concealed, n = 18) with no abnormalities, electrical stage (n = 13) with only electrocardiographic abnormalities, and structural stage (n = 34) with both electrical and structural abnormalities defined by the 2010 Task Force AC criteria. We developed and used a patient-specific parameter estimation protocol based on the multi-scale CircAdapt cardiovascular system model to create virtual AC subjects (Figure: middle). Using the individuals’ RVfw, IVS, and LVfw strain patterns as model input, this protocol automatically estimated regional RV and global IVS and LVfw tissue properties, such as myocardial contractility, stiffness, and activation delay.

Results

The computational model was able to reproduce the regional deformation patterns as measured clinically. Patient-specific parameter estimation results (Figure: right) revealed that clinical AC disease progression is characterized by a decrease in contractility and an increase in stiffness and mechanical delay of the RV myocardial tissue in the basal segment compared to the apex. The subclinical stage subjects showed tissue properties comparable to the control group, including a small apex-to-base heterogeneity in tissue properties.

Conclusion

Our patient-specific modelling approach is able to reveal individual myocardial substrates underlying the regional RV deformation abnormalities. Early abnormalities in RV longitudinal strain are most likely caused by increased heterogeneity in local tissue properties, such as an apex-to-base decrease of contractility, increased of myocardial stiffness, and time to peak stress. Abnormalities in tissue properties may be found already in the subclinical stage. In future studies, this artificial intelligence approach will be used to investigate how these abnormalities relate to disease progression and arrhythmogenic risk.

Abstract Figure. Characterization of AC Disease Substrate

Arrhythmogenic cardiomyopathy is characterized by apex-to-base heterogeneity of right ventricular myocardial contractility and stiffness: an imaging-based patient-specific modeling study

Introduction

Arrhythmogenic Cardiomyopathy (AC) is an inherited cardiac disease, clinically characterized by life-threatening ventricular arrhythmias and progressive cardiac dysfunction. Geno-positive subjects with and without symptoms may suffer from sudden cardiac death. Therefore, early disease expression and risk stratification is important. It has been shown that right ventricular (RV) longitudinal deformation abnormalities in early stages is related to disease progression. We propose an inverse patient-specific computer modelling approach, combined with clinical imaging data, to non-invasively quantify regional ventricular tissue abnormalities in AC mutation carriers.

Purpose

To non-invasively reveal the individual myocardial substrate underlying the regional RV deformation abnormalities in AC mutation carriers.

Methods

In 74 individuals carrying a plakophilin-2 or desmoglein-2 mutation, regional longitudinal deformation patterns of the RV free wall (RVfw), interventricular septum (IVS) and left ventricular free wall (LVfw) were obtained using speckle-tracking echocardiography (Figure: left column). This cohort was subdivided into 3 consecutive clinical stages i.e. subclinical (concealed, n=19) with no abnormalities, electrical stage (n=13) with only electrocardiographic abnormalities, and structural stage (n=42) with both electrical and structural abnormalities defined by the 2010 Task Force AC criteria. We developed and used a patient-specific parameter estimation protocol based on the multi-scale CircAdapt cardiovascular system model to create virtual AC subjects (Figure: middle column). Using the individuals' RV strain patterns as model input, this protocol automatically estimated regional RV tissue properties, such as myocardial contractility and stiffness.

Results

The computational model was able to reproduce the deformation as clinically measured. Patient-specific parameter estimation results (Figure: right column) revealed that clinical AC disease progression is characterized by an increase of base-to-apex heterogeneity in contractility and stiffness of the RV myocardial tissue, with a decreased contractility and an increased stiffness in the basal segment compared to the apex. Although this heterogeneity was most severe in the structural stage group, it was already present in many of the subjects in the subclinical stage. No clear apex-to-base heterogeneity of mechanical activation delay was found in this cohort.

Conclusion

Our patient-specific modelling approach showed that early abnormalities in RV longitudinal strain are most likely caused by increased heterogeneity in local tissue properties. Strain abnormalities are predominantly caused by decreased basal tissue contractility and increased basal tissue stiffness. Abnormalities in tissue properties may be found already in the subclinical stage. Future studies will investigate how these abnormalities relate to disease progression and arrhythmogenic risk.

Characterization of AC Disease Substrate

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): This work was funded by the Netherlands Organisation for Scientific Research and the Dutch Heart Foundation.

Irregular beat-to-beat hemodynamic properties determine left ventricular function during atrial fibrillation

Background

The rapid irregular atrial electrical activity during atrial fibrillation (AF) is associated with an irregular and variable left ventricular (LV) systolic pump function. The effects of cycle length (CL) variations on LV function during AF remain incompletely understood.

Purpose

To elucidate the physiological mechanisms by which beat-to-beat changes in cycle length affect LV function during AF. We hypothesize that changes in LV preload and afterload cause a large part of the beat-to-beat variability of LV function during AF.

Methods

Beat-to-beat speckle-tracking echocardiography was performed in 10 patients with persistent AF. In each patient, a hundred consecutive beats were imaged during AF and we evaluated the relation between longitudinal strain in the image plane (4-chamber view) and (pre-)preceding CL in these patients. We used the CircAdapt cardiovascular system model to simulate cardiac mechanics and hemodynamics during AF for each individual patient 1) by imposing the exact irregular sequence of CLs as measured in the patient and 2) by making the atrial myocardium non-contractile. We also simulated generic (i.e. artificially defined) CL sequences (e.g. irregular long CL, irregular short CL) to better understand the determinants of beat-to-beat variations of LV systolic function during AF.

Results

Generic simulations uncovered the hemodynamic effects of a sudden irregular long or short beat on LV function during the following beat (top). A short beat led to lower LV function in the following beat because of smaller preload, while a longer beat led to larger LV function by Frank-Starling law of contractile myocardium. This CL dependency of LV function was confirmed when analysing clinical data of AF patients (bottom, left). A negative non-linear relation between preceding CL and longitudinal strain was observed (bottom, right). Increased longitudinal strain at high preceding CL (purple box) was explained by a higher preceding EDV (higher preload) (p<0.002). At a given preceding CL, variability in longitudinal strain was explained by the afterload of the preceding beat, with a lower preceding afterload (systolic aortic pressure) leading to higher longitudinal strain (yellow box, p<0.002), but not by changes in preceding preload (non-significant).

Conclusions

Irregularity in preceding CL leads to changes in LV function through preload and afterload changes. Indeed, as observed in patients during AF, longitudinal LV strain depends non-linearly on the preceding CL. Beat-to-beat changes in preload contribute to variable LV function but changes in afterload also are a key determinant of LV function variability at same preceding CL. Our combined clinical-computational study highlights the variability in longitudinal strain measurement during AF and provides new insight into the physiological mechanisms determining LV function in AF patients.

Determinants of LV function in AF

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): NWO-ZonMw, VIDI grant 016.176.340

P989Determinants of beat-to-beat left ventricular function during atrial fibrillation: a combined clinical-computational study

Funding Acknowledgements

Netherlands Organisation for Scientific Research (NWO-ZonMw, VIDI grant 016.176.340)

Background

The rapid irregular atrial electrical activity during atrial fibrillation (AF) is associated with an irregular and variable left ventricular (LV) systolic pump function. The mechanisms determining LV function during AF remain incompletely understood.

Purpose

To assess the reliability of global longitudinal strain (GLS) as a measure of LV function during AF, and to elucidate how beat-to-beat changes in LV preload and afterload affect LV function during AF.

Methods

Beat-to-beat speckle-tracking echocardiography was performed in patients with persistent AF. A hundred consecutive beats in each patient were imaged during AF and we evaluated the relation between GLS in the image plane (4-chamber view) and (pre-)preceding cycle length (CL) in these patients. We used the CircAdapt cardiovascular system model to simulate cardiac mechanics and hemodynamics during AF for each individual patient 1) by imposing the exact irregular sequence of CL as measured in the patient and 2) by making the atrial myocardium non-contractile. These simulations enabled beat-to-beat quantification of preload (end-diastolic volume, EDV), afterload (systolic aortic pressure) and GLS during AF. 

Results

Clinical data and simulations both showed a negative non-linear relation between preceding CL and GLS (Panel A). Non-linearity was more pronounced at low preceding CLs (<750ms), while GLS at preceding CLs >750ms showed less dependence on CL. Simulating ventricular failure by a reduction in ventricular contractility led to a lower overall GLS and a loss of non-linear response at low CL (Panel A, right, diamonds). Increased GLS at high preceding CL (purple box) was explained by a higher preceding EDV (higher preload) (p < 0.002, Panel B), reflecting the Frank-Starling mechanism of contractile myocardium. At a given preceding CL, variability in GLS was explained by the afterload of the preceding beat, with a lower preceding afterload (systolic aortic pressure) leading to higher GLS (Panel C, yellow box, p < 0.002), but not by changes in preceding preload (Panel C, p non-significant). Preload of the pre-preceding beat also correlated with changes in GLS (Panel C, p < 0.005).  

Conclusions

During AF, GLS depends non-linearly on the preceding CL, with GLS measures performed at longer preceding CLs (>750ms in our cohort) showing a low beat-to-beat variability. Beat-to-beat hemodynamic changes in preceding afterload could explain differences in LV function at same preceding CL. Our combined clinical-computational study highlights the variability in GLS measurement during AF and provides new insight into the potential hemodynamic mechanisms determining LV function in AF patients.

Abstract Figure.

P5385Development and preclinical testing of upscaled engineered heart tissue for use in translational studies

Introduction

The lack of efficacy of stem cell therapy for the treatment of heart failure may be related to the poor retention rates offered by existing delivery methods (intra-coronary/ intramyocardial). Tissue engineering strategies improve cell retention in small animal models but data regarding engineered heart tissue (EHT) patches large enough for human studies are lacking.

Purpose

To upscale EHT to a clinically relevant size and mature the patch in-vitro. Once matured to undergo preclinical testing in a rabbit model of myocardial infarction.

Methods

We developed an upscaled EHT patch (3cm x 2cm x 1.5mm) able to contain up to 50 million human induced pluripotent stem cell derived cardiomyocytes (hiPSC-CM; Fig A/B). Myocardial infarction model was performed by permanent ligation.

Results

The patches began to beat spontaneously within 3 days of fabrication and after 28 days of dynamic culture (Late EHTs) showed the development of several mature characteristics when compared to early patches (<14 days from fabrication). For example, late EHTs contained hiPSC-CMs which were more aligned (hiPSC-CM accumulative angle change: early 2702±778 degrees [n=4] vs late 922±186 [n=5], p=0.042); showed better contraction kinetics (early peak contraction amplitude 87.9±5.8a.u. versus late 952±304a.u.; p<0.001) and faster calcium transients (time to peak: early 200.8±8.8ms [n=5] vs late 147.7±10.2ms [n=6], p=0.004; time to 75% decay: early 274±9.7ms vs late 219.9±2.7ms, p=0.0003).

We then tested the EHT patch in-vivo using a rabbit model (Fig C). Patches were applied to normal (n=5) or infarcted hearts (n=8). Sham operations used non-cellular fibrin patches (n=5). The mean fraction of troponin positive cells in the graft was 27.8±10.3% at 25.2±1.7 days relative to day 0 [n=5] and KU80 (human specific marker) staining confirmed that this was of human origin. CD31 (Fig D) and KU80 staining revealed that the grafts were well vascularized and that the vasculature was not human in origin (therefore were originating from the host). Ex-vivo optical mapping revealed evidence of electrical coupling between the graft and host at 2 weeks and preliminary experiments indicated that the patch improved left ventricular function when grafted onto infarcted hearts. Telemetry recordings in vivo and arrhythmia provocation protocols (ex vivo) indicated that the patch was not proarrhythmic.

Figure 1. A/B) EHT Images; C) 20x troponin T (brown) of rabbit myocardium/EHT (2 weeks after grafting), blue counterstain = haematoxylin, red lines = EHT borders; D) 63x CD31 staining (brown) rabbit/EHT border zone (2 weeks after grafting), blue stain = haematoxylin, red lines = graft/host border zones.

Conclusion

We successfully upscaled hiPSC-CM derived EHT to a clinically relevant size and demonstrated feasibility and integration using a rabbit model of myocardial infarction. Tissue engineering strategies may be the preferred modality of cell delivery for future cardiac regenerative medicine studies.

Improving the clinical understanding of hypertrophic cardiomyopathy by combining patient data, machine learning and computer simulations: A case study

•

In this paper, we present how, by combining electrocardiogram and imaging data, machine learning and high performance computing simulations, we identified four phenotypes in hypertrophic cardiomyopathy (HCM), with differences in arrhythmic risk, and provided two distinct possible mechanisms that may explain the heterogeneity of HCM manifestation.

•

This led to a better HCM patient stratification and understanding of the underlying disease mechanisms, providing a step further towards tailored HCM patient management and treatment.

Most patients with hypertrophic cardiomyopathy (HCM), the most common genetic cardiac disease, remain asymptomatic, but others may suffer from sudden cardiac death. A better identification of those patients at risk, together with a better understanding of the mechanisms leading to arrhythmia, are crucial to target high-risk patients and provide them with appropriate treatment. However, this currently remains a challenge. In this paper, we present a successful example of implementing computational techniques for clinically-relevant applications. By combining electrocardiogram and imaging data, machine learning and high performance computing simulations, we identified four phenotypes in HCM, with differences in arrhythmic risk, and provided two distinct possible mechanisms that may explain the heterogeneity of HCM manifestation. This led to a better HCM patient stratification and understanding of the underlying disease mechanisms, providing a step further towards tailored HCM patient management and treatment.

Psychological counseling and accuracy of memory for child sexual abuse

Tens of thousands of child sexual abuse (CSA) cases are reported to authorities annually. Although some of the child victims obtain psychological counseling or therapy, controversy exists about the potential consequences for the accuracy of victims' memory of CSA, both in childhood and adulthood. Yet, delaying needed therapeutic intervention may have detrimental effects on the victims' well-being and recovery. To address this controversy, this study examined whether psychological counseling during a CSA prosecution predicts accuracy or inaccuracy of long-term memory for CSA. Participants (N = 71) were CSA victims who took part in a longitudinal study of memory and legal involvement. Data regarding participants' counseling attendance during the prosecution and details of their CSA cases were gathered throughout legal involvement and shortly thereafter (Time 1). Ten to 16 years later (Time 2), participants were questioned about a range of topics, including the alleged abuse. Time 1 counseling attendance significantly predicted more correct answers to abuse-related questions and (for corroborated cases) fewer overreporting responses at Time 2. Counseling was unrelated to underreporting responses. These results held even with other potential influences, such as abuse severity, victim-defendant relationship, posttraumatic stress disorder criteria met, testifying in the case, and delay, were statistically controlled. Although further research is needed, this study provides evidence that psychological counseling received by CSA victims during or shortly after prosecutions may improve later memory for abuse-related information. (PsycINFO Database Record

Oxidative Stress and Cardiovascular Risk in Type 1 Diabetes Mellitus: Insights From the DCCT/EDIC Study

Background

Hyperglycemia leading to increased oxidative stress is implicated in the increased risk for the development of macrovascular and microvascular complications in patients with type 1 diabetes mellitus.

Methods and Results

A random subcohort of 349 participants was selected from the DCCT / EDIC (Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications) cohort. This included 320 controls and 29 cardiovascular disease cases that were augmented with 98 additional known cases to yield a case cohort of 447 participants (320 controls, 127 cases). Biosamples from DCCT baseline, year 1, and closeout of DCCT , and 1 to 2 years post‐ DCCT ( EDIC years 1 and 2) were measured for markers of oxidative stress, including plasma myeloperoxidase, paraoxonase activity, urinary F 2α isoprostanes, and its metabolite, 2,3 dinor‐8 iso prostaglandin F 2α . Following adjustment for glycated hemoblobin and weighting the observations inversely proportional to the sampling selection probabilities, higher paraoxonase activity, reflective of antioxidant activity, and 2,3 dinor‐8 iso prostaglandin F 2α , an oxidative marker, were significantly associated with lower risk of cardiovascular disease (−4.5% risk for 10% higher paraoxonase, P <0.003; −5.3% risk for 10% higher 2,3 dinor‐8 iso prostaglandin F 2α , P =0.0092). In contrast, the oxidative markers myeloperoxidase and F 2α isoprostanes were not significantly associated with cardiovascular disease after adjustment for glycated hemoblobin. There were no significant differences between DCCT intensive and conventional treatment groups in the change in all biomarkers across time segments.

Conclusions

Heightened antioxidant activity (rather than diminished oxidative stress markers) is associated with lower cardiovascular disease risk in type 1 diabetes mellitus, but these biomarkers did not change over time with intensification of glycemic control.

Clinical Trial Registration

URL : https://www.clinicaltrials.gov . Unique identifiers: NCT 00360815 and NCT 00360893.

Increasing medical students' engagement in public health: case studies illustrating the potential role of online learning

BACKGROUND

The value of e-learning in medical education is widely recognized but there is little evidence of its value in teaching medical students about public health. Such evidence is needed because medical students' engagement with public health has been low. We present three recent case studies from UK medical schools to illustrate diverse ways in which online approaches can increase medical students' engagement with learning public health.

METHODS

A comparative case study approach was used applying quantitative and qualitative data to examine engagement in terms of uptake/use amongst eligible students, acceptability and perceived effectiveness using an analytic framework based on Seven Principles of Effective Teaching.

RESULTS

Across the three case studies, most (67-85%) eligible students accessed online materials, and rated them more favourably than live lectures. Students particularly valued opportunities to use e-learning flexibly in terms of time and place. Online technologies offered new ways to consolidate learning of key public health concepts. Although students found contributing to online discussions challenging, it provided opportunities for students to explore concepts in depth and enabled students that were uncomfortable speaking in face-to-face discussions to participate.

CONCLUSIONS

E-learning can be applied in diverse ways that increase medical student engagement with public health teaching.

Making the case for a 'fifth wave' in public health

This paper will argue that the UK has seen several phases of public health improvement since the Industrial Revolution, and that each of these can be linked to major shifts in thinking about the nature of society and health itself. The authors are not, however, attempting to delineate firm sequences of events (or imply causality) as this would require a level of analysis of the relationship between economy, society and culture which is beyond the scope of this paper. Rather, it is suggested that each phase of health improvement can be thought of in metaphorical terms as a 'wave'. The first wave is associated with great public works and other developments arising from social responses to the profound disruptions which followed the Industrial Revolution. The second wave saw the emergence of medicine as science. The third wave involved the redesign of our social institutions during the 20th Century and gave birth to the welfare state. The fourth wave has been dominated by efforts to combat disease risk factors and the emergence of systems thinking. Although a trough of public health activity continues from each wave, none exerts the same impact as when it first emerged. This paper will discuss the complex challenges of obesity, inequality and loss of wellbeing, together with the broader problems of exponential growth in population, money creation and energy usage. As exponential growth is unsustainable on a finite planet, inevitable change looms. Taken together, these analyses suggest that a fifth wave of public health development is now needed; one which will need to differ radically from its forerunners. The authors invite others to join them in envisioning its nature and in furthering the debate about future public health.

A Metachronous Case of Gastric Lymphoma and Gastric Adenocarcinoma

The occurrence of gastric adenocarcinoma and gastric lymphoma in the same patient is very rare despite a major shared risk factor in the form of Helicobacter pylori infection. We report on a 48 year old who presented with MALT lymphoma, managed with Helicobacter eradication therapy, who presented with gastric adenocarcinoma ten years later. We suggest that MALT lymphoma patients may require extended follow up, or indeed could benefit from regular H. pylori screening programmes.

Risk management, or just a different risk?

BACKGROUND

National reporting of adverse incidents has resulted in a number of clinical alerts being issued. Despite a lack of evidence, these alerts are often accompanied by a mandatory requirement to alter practice. There is likely to be clinician resistance to such a method of change management, particularly where evidence of safety is missing.

AIM

To determine the level of implementation within neonatal units of an alert requiring the change from litmus to pH paper to test nasogastric tube position.

METHOD

A questionnaire sent to all neonatal units in the United Kingdom with more than 12 cots.

RESULTS

From the 207 questionnaires sent, there were 165 (80%) responses. Fifty five percent of units were still using litmus. All continued to use supplementary tests not recommended in best practice statements issued at the time of the alert. There was considerable variation in the pH value at which it was considered safe to feed.

CONCLUSIONS

Nine months after the alert, more than half the units had not changed to pH paper, and supplementary methods of testing were still being used. The wide range of pH values highlights the uncertainty about the "normal" gastric pH in the newborn. The evidence that, in neonatal units, changing to pH paper is safer than the long established use of litmus is lacking. Recommendations for change in practice must be based on good information and not seen just as a "knee jerk" response to adverse incidents.