Comparison of growth performance and tissue cobalt concentrations in beef cattle fed inorganic and organic cobalt sources

Cobalt is an essential trace mineral required for ruminal vitamin B12 synthesis, but sources differ in ruminal microbial utilization, i.e., cobalt carbonate is poorly water soluble, whereas acetate and lactate forms are water soluble. Reports comparing organic cobalt lactate to other cobalt salts are lacking. The study objective was to determine if feeding cobalt lactate at two inclusion rates resulted in similar growth performance and tissue cobalt concentrations as the carbonate and acetate forms used in feeds. One hundred Angus cross bred steers weighing 385 ± 20 kg were randomly assigned to one of five treatments. Cattle were fed a basal diet plus: 1) cobalt carbonate to supply cobalt at 30 mg/steer/d, 2) cobalt acetate to supply cobalt at 30 mg/steer/d, 3) cobalt acetate to supply cobalt at 60 mg/steer/d, 4) cobalt lactate to supply cobalt at 30 mg/steer/d, and 5) cobalt lactate to supply cobalt at 60 mg/steer/d. Cattle were fed according to industry standards until body fat deposition was visually deemed to grade USDA Choice, which was 92 and 117 d for each of the 2 blocks, respectively. Steers were harvested and carcass measurements recorded along with sampling of adipose, heart, kidney, liver, and muscle for tissue cobalt concentrations. Three statistical contrasts consisted of: 1: inorganic (cobalt carbonate) vs. organic (cobalt acetate and lactate); 2: cobalt acetate vs. cobalt lactate; and 3: feeding rate of 30 vs. 60 mg/steer/d cobalt. Body weight gains, average daily gains, dry matter intake, and feed conversions were similar (P > 0.10) for steers fed all cobalt sources and feeding rates. Hot carcass weight, yield grade, back fat thickness, and ribeye area were similar (P > 0.10) among steers fed all cobalt sources and inclusion rates. Liver, kidney, muscle, and adipose cobalt concentrations were similar (P > 0.08) for steers fed inorganic vs. organic cobalt sources. Feeding cobalt lactate compared with cobalt acetate did not affect (P > 0.10) liver, kidney, heart, muscle, and adipose tissue cobalt concentrations. Feeding 60 mg/steer/d cobalt compared with 30 mg/steer/d increased (P < 0.01) liver, kidney, heart, and adipose tissue cobalt concentrations, while muscle was a tendency (P < 0.06). The study demonstrated that feeding soluble cobalt lactate, a new cobalt source, resulted in similar growth performance, carcass characteristics, and tissue cobalt concentrations when compared with cobalt acetate and carbonate.

Electrocardiogram metrics identify ionic current dysregulation relevant to atrial fibrillation

Background

Personalisation of pharmacological treatment for atrial fibrillation (AF) is challenging. Pharmacological ionic current blockers such as digoxin or flecainide are commonly used, with caution given possible cardiotoxicity and proarrhythmia. Moreover, patients are stratified based on their associated heart disease rather than individual electrophysiological substrate, in part due to the inability for its non-invasive characterisation. Here we hypothesise that the ECG may contain information on key ionic currents regulating AF initiation and sustenance, and which would enable personalisation of pharmacological treatments to increase safety and efficacy.

Purpose

To identify clinical ECG markers that reflect dysregulation of key ionic currents for AF using modelling and simulation in populations of whole-atria models without structural heart disease.

Methods

Experimental data obtained from human AF and control patients was used to develop a virtual population of 200 whole-atria models (Figure, organ-level) with individual ionic profiles (Figure 1, bottom-left), including electrophysiological regional inhomogeneities (Figure 1, bottom-right). Modified-limb 12 lead ECGs were computed during sinus rhythm (Figure 1, body-surface-level) and biomarkers were quantified for the P and Ta-waves, such as duration, time-to-peak, decay, dispersion, amplitude and P-wave terminal force.

Results

Simulated modified-limb ECG consistently reproduced the clinical ECG observed in human subjects, with an apparent Ta-wave inversion in lead II (Figure 1, body-surface-level). The inward rectified K+ current (IK1), known to be critical for AF, was the only ionic current associated with Ta-wave duration, showing an inversely proportional relationship (236±48 vs. 466±53 ms, IK1 up-regulation vs. down-regulation in lead V5; median ± interquartile range; P&lt;0.001). Elevated IK1 additionally yield Ta-wave inversion in lead V5 and a higher Ta-wave magnitude in lead II (0.15±0.03 vs. 0.07±0.04 mV, IK1 up-regulation vs. down-regulation; P&lt;0.001). However, Ta-wave magnitude showed a predominant relationship with the Na+/K+ pump (INaK), especially in the precordial leads (0.17±0.13 vs. 0.07±0.04 mV, INaK up-regulation vs. down-regulation in V5; P&lt;0.001). Thus, the up-regulation of both currents led to very short, high-amplitude Ta-waves. While elevated IK1 additionally increased the P-wave terminal force (1.58±0.37 vs. 1.31±0.33 mV ms, IK1 up-regulation vs. down-regulation; P&lt;0.001), a higher increase was observed for decreased fast Na+ current (INa) (1.35±0.17 vs. 1.86±0.30 mV ms, INa up-regulation vs. down-regulation; P&lt;0.001).

Conclusion

Ta-wave duration and amplitude are revealing of IK1 and INaK dysregulation, respectively, holding potential for improving cardiac safety and efficacy through a better stratification of AF patients for pharmacological treatment.

Funding Acknowledgement

Type of funding sources: Public grant(s) – EU funding. Main funding source(s): European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 860974

Modelling and in silico simulation of human induced pluripotent stem cell derived cardiomyocyte electro-mechanical properties

Funding Acknowledgements

Type of funding sources: Foundation. Main funding source(s): BHF

Background

Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CM) enable accessible human data-based cardiology studies. However, a caveat in hiPSC-CM-based studies is their immature electrophysiological and contractile phenotype. One of the modifications occurring during hiPSC-CM maturation is the change in myofilament calcium sensitivity, an important indicator of cardiac muscle function [1, 2]. In silico hiPSC-CM investigations could help improve understanding of the hiPSC-CM-specific contractile behaviour and its changes during maturation. Considering the growing use of hiPSC-CM, it is vital to enable investigations of hiPSC-CM-specific contractile features.

Purpose

To address the need of hiPSC-CM model with integrated contractile element, our goal is to develop an electromechanical human data-based iPSC-CM computer model. We aim to use the model to investigate the effects of the changes in myofilament calcium sensitivity on hiPSC-CM electrophysiology and contractility.

Methods

We coupled a published hiPSC-CM electrophysiological model [3] with a model of the human adult cardiomyocyte contractile machinery [4] by linking intracellular calcium and calcium-bound troponin dynamics. The established electromechanical hiPSC-CM model was calibrated using experimental hiPSC-CM active tension data and its simulated electromechanical biomarkers were also evaluated against experimental action potential and calcium transient data. We conducted a sensitivity analysis to investigate the effects of changes in myofilament calcium sensitivity on the electrophysiology and contractility of the cell.

Results

First, we demonstrated that the model successfully reproduces the hiPSC-CM contractile phenotype. Simulations showed a peak twitch tension of 0.44 kPa which takes 201 ms to peak and 164 ms to achieve 50% relaxation, which all agree with the experimental hiPSC-CM values. Simulated calcium transient and action potential biomarkers remain within the experimentally established ranges after electromechanical coupling. The sensitivity analysis of the hiPSC-CM model focused on the myofilament calcium sensitivity effects showed an increase in active tension amplitude with a decrease in calcium transient peaks upon increased myofilament calcium sensitivity. Large increases in myofilament calcium sensitivity result in depolarization failure with low amplitude fluctuations of membrane voltage, calcium transient and active tension. Altogether simulation results demonstrate the usability of the model for simulating and exploring not only physiological, but also pathological cardiac conditions.

Conclusions

We present a new electromechanical hiPSC-CM model for in silico hiPSC-CM-based studies. The model has been evaluated against experimental data and has demonstrated the capacity to generate key electrophysiological currents, active tension as well as myofilament calcium sensitivity-induced electromechanical abnormalities.

Utilization of remote access electron microscopes to enhance technology education and foster STEM interest in preteen students

Remote access technology in STEM education fills dual roles as an educational tool to deliver science education (Educational Technology) and as a means to teach about technology itself (Technology Education). A five-lesson sequence was introduced to eleven to twelve-year-old students at an urban school. The lesson sequences were inquiry-based, hands-on, and utilized active learning pedagogies which have been implemented in STEM classrooms worldwide. Each lesson employed a Scanning Electron Microscope (SEM) and Energy Dispersive Spectroscopy (EDS) accessed remotely. Students were assessed using multiple choice questions to ascertain (1) technology education learning gains: did students gain an understanding of how electron microscopes work? and (2) educational technology learning gains: did students gain a better understanding of lesson content through use of the electron microscope? Likert-item surveys were developed, distributed and analyzed to established how remote access technology affected student attitudes toward science, college, and technology. Participating students had a positive increase in attitudes toward scientific technology by engaging in the lesson sequences; reported positive attitudes toward remote access experiences; and exhibited learning gains in the science behind the SEM technology they accessed remotely. These findings suggest that remote experiences are a strong form of technology education, but also that future research could explore ways to strengthen remote access as an educational technology (a tool to deliver lesson content), such as one-on-one engagement. This study promotes future research into inquiry-based, hands-on, integrated lessons approach that utilize educational technology learning through remote instruments as a pedagogy to increase students' engagement with and learning of the T in STEM.

Correlates of psychological intimate partner violence with HIV care outcomes on patients in HIV care

Background

Among people living with HIV (PLWH), physical intimate partner violence (IPV) is associated with poor virologic, psychiatric, and behavioral outcomes. We examined non-physical, psychological intimate partner violence (psy-IPV) and HIV care outcomes using data from two U.S. consortia.

Methods

We conducted multivariable analyses with robust standard errors to compare patients indicating/not indicating psy-IPV.

Results

Among PLWH (n = 5950), 9.5% indicated psy-IPV; these individuals were younger (− 3; 95% CI [− 2,-4], p-value < 0.001), less likely to be on antiretroviral treatment (ART) (0.73 [0.55,0.97], p = 0.03), less adherent to ART (− 4.2 [− 5.9,-2.4], p < 0.001), had higher odds of detectable viral load (1.43 [1.15,1.78], p = 0.001) and depression (2.63 [2.18,3.18], p < 0.001), and greater use of methamphetamines/crystal [2.98 (2.30,3.87),p < 0.001], cocaine/crack [1.57 (1.24,1.99),p < 0.001], illicit opioids [1.56 (1.13,2.16),p = 0.007], and marijuana [1.40 (1.15,1.70), p < 0.001].

Conclusion

Psychological IPV, even in the absence of physical or sexual IPV, appears to be associated with HIV care outcomes and should be included in IPV measures integrated into routine HIV care.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-021-11854-x.

Human-based computational and experimental investigation of disease mechanisms in mutation-specific hypertrophic cardiomyopathy

Funding Acknowledgements

Type of funding sources: Public grant(s) – EU funding. Main funding source(s): European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement 764738. British Heart Foundation Intermediate Basic Science Fellowship (FS/17/22/32644).

Background

The pathogenic TNNI3R21C/+ variant causes malignant hypertrophic cardiomyopathy (HCM) with high incidence of sudden cardiac death, even in individuals absent of hypertrophy. There is evidence to support a known biophysical defect in the protein, yet the cellular mechanisms that precipitate adverse clinical outcomes remain unclear.

Purpose

We aim to computationally model and map the TNNI3R21C/+ cellular phenotype observed in induced pluripotent stem cell derived cardiomyocytes (iPSC-CMs) to human disease, thereby explaining the key mechanisms driving HCM in TNNI3R21C/+ variant carriers. 

Methods

Wild-type (WT) and TNNI3R21C/+ iPSC-CMs were characterised by calcium transient analysis and direct sarcomere tracking to assess cellular contraction and relaxation. In-vitro data was used to inform the in-silico modelling of human cardiomyocytes. We constructed an in-silico population of WT adult cardiomyocytes and used it to transform the in-vitro data into corresponding adult phenotypes by means of a novel iPSC-to-adult data mapping. We tested the hypothesis that the abnormal TNNI3R21C/+ phenotype observed in iPSC-CMs would be explained by alterations in calcium affinity of troponin and increased myofilament calcium sensitivity. 

Results

Analysis of in-vitro iPSC-CM data showed that TNNI3R21C/+ cells exhibit increased contractility with slowed relaxation when compared to WT. They also exhibited a faster rise in the calcium transient with a slowed calcium decay in comparison to WT. The in-silico adult TNNI3R21C/+ phenotype from the iPSC-to-adult mapping replicated the abnormalities observed in iPSC-CMs. The WT in-silico population accurately covered the ranges of electromechanical biomarkers providing a representative cohort of physiological variability. The TNNI3R21C/+ calcium phenotype could be recovered by our in-silico mutant models. Simulation results suggest that calcium abnormalities in TNNI3R21C/+ are a direct consequence of abnormal calcium buffering by thin filaments, mediated by increases in calcium affinity of troponin and myofilament calcium sensitivity. The TNNI3R21C/+ phenotype could not be recovered if these two factors were considered in isolation. Corresponding contractility analyses of in-silico models showed that the calcium level changes caused by the TNNI3R21C/+ phenotype are associated with hypercontractility and diastolic dysfunction, well-known hallmarks of HCM, which were also observed in the iPSC-CM model of disease.

Conclusions

This study showcases human-based computational and experimental methodologies that unearth direct mechanistic explanations of phenotypes driven by the TNNI3R21C/+ HCM variant. We show that the TNNI3R21C/+ HCM-causing mutation exhibits multifactorial remodelling of troponin calcium affinity and myofilament calcium sensitivity. Unearthing mechanistic pathways in mutation-specific HCM will be key to develop effective pharmacological interventions for a wide variety of understudied variants.

Post myocardial infarction ionic remodelling promotes repolarisation dispersion and electrocardiogram abnormalities in acute and chronic stages

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Wellcome Trust

Background

Sudden cardiac death (SCD) occurs in both acute and chronic stages post myocardial infarction (MI), and the left ventricular ejection fraction (LVEF) and electrocardiogram (ECG) characteristics are important biomarkers for clinical decision making. While various ionic remodelling has been reported in literature at various stages post-MI, the effect of them on clinical biomarkers have not been fully explored.

Purpose

Evaluate the effects of cellular ionic remodelling in acute and chronic post myocardial infarction on ECG and LVEF biomarkers through computational modelling and simulations of human biventricular electromechanics.

Methods

An electromechanical coupled biventricular model with ToR-ORd (Tomek 2019) human electrophysiology coupled with human excitation-contraction machinery (Land 2017) and orthotropic passive mechanics (Holzapfel 2009) was used as baseline model. The 12-lead ECG were simulated at standard body-surface electrode locations, and the biventricular pressure volume loop was simulated to quantify the simulated LVEF. A cardiac magnetic resonance (CMR) derived human biventricular geometry (Strocchi 2020) was used in combination with rigidly aligned torso geometry (Minchole 2019). An anterior sub-endocardial infarction was delineated with infarct, border zone (BZ) and remote zone (RZ) regions. For acute infarction, three types of BZ ionic remodelling from literature, and their effects on simulated LVEF and ECG characteristics were quantified. For chronic infarction, a single chronic BZ ionic remodelling was combine with two different models of RZ ionic remodelling from literature, and the effects of these remodelling on the simulated LVEF and ECG were quantified. The electromechanical properties of the sub-endocardial infarct region did not significantly affect simulated ECG or LVEF biomarkers.

Results

For the acute phase, simulations showed pre-cordial ECG abnormalities for all three BZ models, with T-wave inversion and QT prolongation (80 ms) in BZ1, ST-segment elevation with T-wave inversion in BZ2, and decreased T-wave amplitude in BZ3. Activation maps showed conduction block in BZ2 simulations, leading to ST-segment elevation. Repolarisation maps showed high dispersion in BZ1 simulations, leading to T-wave inversion. LVEF for BZ2 decreased by 4% (from 57% in control) due to conduction block in BZ and lack of contraction in that region, LVEF remained constant for BZ1 and BZ3 simulations. For the chronic phase, there was QT prolongation in both RZ1 (80 ms) and RZ2 (170 ms) as well as decreased T-wave amplitude, reflected by elevated repolarisation dispersion. LVEF was not significantly altered for either simulations.

Conclusions

Post-MI ionic remodelling at the acute and chronic stages cause varying degrees of dispersion of repolarisation and T-wave and ST-segment abnormalities, with minimal effect on mechanical function, except in the case of severe conduction abnormality. Abstract Figure.

Brief Report: Weight Gain Following ART Initiation in ART-Naïve People Living With HIV in the Current Treatment Era

OBJECTIVES

Evaluate differences in weight change by regimen among people living with HIV (PLWH) initiating antiretroviral therapy (ART) in the current era.

METHODS

Between 2012 and 2019, 3232 ART-naïve PLWH initiated ≥3-drug ART regimens in 8 Centers for AIDS Research Network of Integrated Clinical Systems sites. We estimated weight change by regimen for 11 regimens in the immediate (first 6 months) and extended (all follow-up on initial regimen) periods using linear mixed models adjusted for time on regimen, interaction between time and regimen, age, sex, race/ethnicity, hepatitis B/C coinfection, nadir CD4, smoking, diabetes, antipsychotic medication, and site. We included more recently approved regimens [eg, with tenofovir alafenamide fumarate (TAF)] only in the immediate period analyses to ensure comparable follow-up time.

RESULTS

Mean follow-up was 1.9 years on initial ART regimen. In comparison to efavirenz/tenofovir disoproxil fumarate (TDF)/emtricitabine (FTC), initiating bictegravir/TAF/FTC {3.9 kg [95% confidence interval (CI): 2.2 to 5.5]} and dolutegravir/TAF/FTC [4.4 kg (95% CI: 2.1 to 6.6)] were associated with the greatest weight gain in the immediate period, followed by darunavir/TDF/FTC [3.7 kg (95% CI: 2.1 to 5.2)] and dolutegravir/TDF/FTC [2.6 kg (95% CI: 1.3 to 3.9)]. In the extended period, compared with efavirenz/TDF/FTC, initiating darunavir/TDF/FTC was associated with a 1.0 kg (95% CI: 0.5 to 1.5) per 6-months greater weight gain, whereas dolutegravir/abacavir/FTC was associated with a 0.6-kg (95% CI: 0.3 to 0.9) and dolutegravir/TDF/FTC was associated with a 0.6-kg (95% CI: 0.1 to 1.1) per 6-months greater gain. Weight gain on dolutegravir/abacavir/FTC and darunavir/TDF/FTC was significantly greater than that for several integrase inhibitor-based regimens.

CONCLUSIONS

There is heterogeneity between regimens in weight gain following ART initiation among previously ART-naïve PLWH; we observed greater gain among PLWH taking newer integrase strand transfer inhibitors (DTG, BIC) and DRV-based regimens.

Statistical control of processes applied to geometric uncertainties for CTV expansion margins determination in prostate cancer patients treated with VMAT: a prospective study in 57 patients

PURPOSE

To study the control graphs applicability for the geometric uncertainties of VMAT treatments in prostate cancer patients, and their use to verify the hypothesis of the data obtained randomness, to apply the margins of Van Herk expression.

MATERIAL AND METHODS

During the first 5 days of treatment, and then once a week, a Kv CBCT was performed, compared with the simulation CT and adjusted the displacements, to determine the inter-fraction errors. Immediately after radiation therapy, another CBCT was performed (for intra-fraction errors). With these data, the X, R position control charts have been made. The patients, not maintained the deviations within the charts control limits, were called "anomalies". Then, we compared the deviations and margins calculated with the van Herk expression for all patients and for those without anomalies.

RESULTS

The margins determined show appreciable differences if there were calculated for the total set of patients or for the set of them without anomalies in the control charts. For the overall set of patients, the lateral, longitudinal, and vertical margins were 0.45 cm, 0.52 cm, 0.56 cm, while for the set of patients without anomalies were 0.29 cm, 0.35 cm, and 0.38 cm.

CONCLUSIONS

The use of control charts allows tracking geometric deviations both inter and intra-fraction, variability real-time control and to detect situations in which it can change for non-random reasons, and require immediate investigation. Maintaining geometric deviations in the control state decreases the margins needed to administer a high dose to CTV in a high percentage of cancer prostate patients.

Sensitivity analysis of a strongly-coupled human-based electromechanical cardiac model: Effect of mechanical parameters on physiologically relevant biomarkers

The human heart beats as a result of multiscale nonlinear dynamics coupling subcellular to whole organ processes, achieving electrophysiologically-driven mechanical contraction. Computational cardiac modelling and simulation have achieved a great degree of maturity, both in terms of mathematical models of underlying biophysical processes and the development of simulation software. In this study, we present the detailed description of a human-based physiologically-based, and fully-coupled ventricular electromechanical modelling and simulation framework, and a sensitivity analysis focused on its mechanical properties. The biophysical detail of the model, from ionic to whole-organ, is crucial to enable future simulations of disease and drug action. Key novelties include the coupling of state-of-the-art human-based electrophysiology membrane kinetics, excitation-contraction and active contraction models, and the incorporation of a pre-stress model to allow for pre-stressing and pre-loading the ventricles in a dynamical regime. Through high performance computing simulations, we demonstrate that 50% to 200% - 1000% variations in key parameters result in changes in clinically-relevant mechanical biomarkers ranging from diseased to healthy values in clinical studies. Furthermore mechanical biomarkers are primarily affected by only one or two parameters. Specifically, ejection fraction is dominated by the scaling parameter of the active tension model and its scaling parameter in the normal direction ( k ort 2 ); the end systolic pressure is dominated by the pressure at which the ejection phase is triggered ( P ej ) and the compliance of the Windkessel fluid model ( C ); and the longitudinal fractional shortening is dominated by the fibre angle ( ϕ ) and k ort 2 . The wall thickening does not seem to be clearly dominated by any of the considered input parameters. In summary, this study presents in detail the description and implementation of a human-based coupled electromechanical modelling and simulation framework, and a high performance computing study on the sensitivity of mechanical biomarkers to key model parameters. The tools and knowledge generated enable future investigations into disease and drug action on human ventricles.

Anemia risk factors among people living with HIV across the United States in the current treatment era: a clinical cohort study

Background

Anemia is common among people living with HIV infection (PLWH) and is associated with adverse health outcomes. Information on risk factors for anemia incidence in the current antiretroviral therapy (ART) era is lacking.

Methods

Within a prospective clinical cohort of adult PLWH receiving care at eight sites across the United States between 1/2010–3/2018, Cox proportional hazards regression analyses were conducted among a) PLWH free of anemia at baseline and b) PLWH free of severe anemia at baseline to determine associations between time-updated patient characteristics and development of anemia (hemoglobin < 10 g/dL), or severe anemia (hemoglobin < 7.5 g/dL). Linear mixed effects models were used to examine relationships between patient characteristics and hemoglobin levels during follow-up. Hemoglobin levels were ascertained using laboratory data from routine clinical care. Potential risk factors included: age, sex, race/ethnicity, body mass index, smoking status, hazardous alcohol use, illicit drug use, hepatitis C virus (HCV) coinfection, estimated glomerular filtration rate (eGFR), CD4 cell count, viral load, ART use and time in care at CNICS site.

Results

This retrospective cohort study included 15,126 PLWH. During a median follow-up of 6.6 (interquartile range [IQR] 4.3–7.6) years, 1086 participants developed anemia and 465 participants developed severe anemia. Factors that were associated with incident anemia included: older age, female sex, black race, HCV coinfection, lower CD4 cell counts, VL ≥400 copies/ml and lower eGFR.

Conclusion

Because anemia is a treatable condition associated with increased morbidity and mortality among PLWH, hemoglobin levels should be monitored routinely, especially among PLWH who have one or more risk factors for anemia.

28Impact of non-invasive rapid cardiac magnetic resonance for the assessment of cardiomyopathies in developing countries

Background

Cardiovascular mortality is higher in developing countries. Part of that is suboptimal testing. Cardiac magnetic resonance (CMR) is the gold standard for measuring structure, function of the heart and adds incremental value by imaging scarring and to assess iron level. Despite the existence of MRI units, CMR is identified as a complex test, with poor training and availability in developing countries.

Purpose

To assess the potential impact of a faster CMR protocol at a multicentre level in developing countries; implementing it with an education program, for the assessment cardiomyopathies.

Methods

An international partnership. A rapid CMR protocol for the evaluation of cardiac volumes, function and tissue characterization (Cardiac Iron T2* and LGE for scar) Figure 1a. We deployed the protocol as a multicentre study: Argentina, Peru, India and South Africa accompanied by a program of education. Pre-scan clinical information, scanning data: complications, image quality and post-scan follow-up of participants for the assessment on impact, between 3 to 24 months.

Results

510 scans (4 countries, 6 cities, 12 centres) were performed with the rapid CMR protocol. Contrast studies in 378 (74%). There were no scan-related complications. Quality of the studies was maintained in a high level as an average of 89%. 97% of studies responded referral's question. All patients with contrast CMR scan have had at least one 2D echocardiogram before CMR. Average scan duration was 21±6 mins for contrast studies and 12±3 for non-contrast T2* protocol. The most common underlying diagnoses were non-ischaemic cardiomyopathy in 73% of participants (including cardiac iron level assessment in 26%, HCM in 17%, DCM in 15%), 27% for ischaemic cardiomyopathy and 15% for other pathologies. 4 of the 12 participant centres started to incorporate CMR for the first time. Findings impacted management in 60% of patients, including new diagnosis in 21% of participants. See table 1, figure 1b. For just cardiac iron assessment: 1/3 of participants had iron deposited in the heart with 14% of patients in severe levels.

Conclusions

CMR can be delivered faster and easier. When this abbreviated protocol is enabled with education, it can be implemented in developing countries with existing technology. This protocol shows high quality exam, with an important impact on patient's management.

Characteristics and impact on management Contrast studies Non-contrast studies All patients (%) 378 (74) 132 (36) Age, mean (range) years 54 (16–93) 24 (13–41) Male (%) 151 (39) 64 (48) Pre-echocardiography exam (%) 370 (98) 42 (32) Scanning duration mean (SD) 21 (6) 12 (3) Good quality exam (%) 329 (87) 120 (91) Impact on management Total All patients (%) 510 (100) Completely new diagnosis (%) 105 (21) Change/Addition of Medication (%) 128 (25) Intervention/ Surgery (%) 31 (6) Invasive angiography/biopsy (%) 25 (5) Hospital discharge/admission (%) 15 (3) TOTAL 306 (60%) SD: Standard Deviation.

Acknowledgement/Funding

Global Engagement UCL, UK Foreign & Commonwealth Office and The Peruvian Scientific, Technological Development and Technological Innovation (FONDECYT)

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.

Making it RAIN: Using Remotely Accessible Instruments in Nanotechnology to Enhance High School Science Courses

The Remotely Accessible Instruments in Nanotechnology (RAIN) Network is a conglomerate of nineteen community colleges, four-year universities and high school sites that aims to enhance STEM learning by bringing advanced technologies to K-12 education. RAIN provides free remote access to instruments such as Scanning Electron, Atomic Force and Transmission Electron Microscopes, as well as Energy Dispersive and Infrared Spectroscopy. The following is a variety of experiments and an empirical formula lab that can be performed in a high school physical science or chemistry classroom that utilizes the RAIN Network.

Light up My Life: An Active Learning Lab to Elucidate Conductive Properties of Electrolytes

Understanding molecular structure and its influence on chemical reactivity is a fundamental component in Chemistry curriculum. For example, acidic protons ionize, or ionic solids dissociate to form charge, inducing electrolyte properties depending on molecular structure. An active learning lab is designed to demonstrate connection between electrolyte behavior and structure of various molecules. Experiments are shared to show interdisciplinary aspect of electrolytes within biology and chemistry. Specifically, how biomolecules exhibit electrolyte behavior due to chemical composition.

Slow Adaptation of Ventricular Repolarization as a Cause of Arrhythmia?

Introduction: This article is part of the Focus Theme of Methods of Information in Medicine on “Biosignal Interpretation: Advanced Methods for Studying Cardiovascular and Respiratory Systems”.

Background: Adaptation of the QT-interval to changes in heart rate reflects on the body-surface electrocardiogram the adaptation of action potential duration (APD) at the cellular level. The initial fast phase of APD adaptation has been shown to modulate the arrhythmia substrate. Whether the slow phase is potentially proarrhythmic remains unclear.

Objectives: To analyze in-vivo human data and use computer simulations to examine effects of the slow APD adaptation phase on dispersion of repolarization and reentry in the human ventricle.

Methods: Electrograms were acquired from 10 left and 10 right ventricle (LV/RV) endocardial sites in 15 patients with normal ventricles during RV pacing. Activation-recovery intervals, as a surrogate for APD, were measured during a sustained increase in heart rate. Observed dynamics were studied using computer simulations of human tissue electrophysiology.

Results: Spatial heterogeneity of rate adaptation was observed in all patients. Inhomogeneity in slow APD adaptation time constants (ΔTs) was greater in LV than RV (ΔTs LV = 31.8 ± 13.2, ΔTs RV = 19.0 ± 12.8 s, P < 0.01). Simulations showed that altering local slow time constants of adaptation was sufficient to convert partial wavefront block to block with successful reentry.

Conclusions: Using electrophysiological data acquired in-vivo in human and computer simulations, we identify heterogeneity in the slow phase of APD adaptation as an important component of arrhythmogenesis.

CONTEXTUALIZING TECHNOLOGY IN THE CLASSROOM VIA REMOTE ACCESS: USING SPACE EXPLORATION THEMES AND SCANNING ELECTRON MICROSCOPY AS TOOLS TO PROMOTE ENGAGEMENT IN GEOLOGY/CHEMISTRY EXPERIMENTS

A multidisciplinary science experiment was performed in K-12 classrooms focusing on the interconnection between technology with geology and chemistry. The engagement and passion for science of over eight hundred students across twenty-one classrooms, utilizing a combination of hands-on activities using relationships between Earth and space rock studies, followed by a remote access session wherein students remotely employed the use of a scanning electron microscope (SEM) and energy-dispersive spectroscopy (EDS) to validate their findings was investigated. Participants represent predominantly low-income minority communities, with little exposure to the themes and equipment used, despite being freely available resources. Students indicated greatly increased interest in scientific practices and careers, as well as a better grasp of the content as a result of the lab and remote access coupling format.

Cultivating Mars: A Project-Based Learning Lab Analyzing an Oxygen Based Redox Reaction in Order to Design an Oxygen-Rich Environment on the Red Planet

In a series of activities/labs, designed in a building block approach, whereas each subsequent lab builds into the next, students will explore the reactivity and production of oxygen in various biological and chemical systems. Through student-constructed analyses, participants will optimize oxygen-generating systems for the colonization of Mars, wherein their system will be used as part of a narrative to construct a livable habitat for future astronauts. Use of remote access technology to a Scanning Electron Microscope (SEM) with elemental analysis capabilities allows students to investigate their oxygen reaction via formation of iron oxide, resulting in rich multidimensional and contextualized scientific exploration in the chemistry classroom.

δ-cells and β-cells are electrically coupled and regulate α-cell activity via somatostatin

Key points

We used a mouse expressing a light‐sensitive ion channel in β‐cells to understand how α‐cell activity is regulated by β‐cells.

Light activation of β‐cells triggered a suppression of α‐cell activity via gap junction‐dependent activation of δ‐cells.

Mathematical modelling of human islets suggests that 23% of the inhibitory effect of glucose on glucagon secretion is mediated by β‐cells via gap junction‐dependent activation of δ‐cells/somatostatin secretion.

Abstract

Glucagon, the body's principal hyperglycaemic hormone, is released from α‐cells of the pancreatic islet. Secretion of this hormone is dysregulated in type 2 diabetes mellitus but the mechanisms controlling secretion are not well understood. Regulation of glucagon secretion by factors secreted by neighbouring β‐ and δ‐cells (paracrine regulation) have been proposed to be important. In this study, we explored the importance of paracrine regulation by using an optogenetic strategy. Specific light‐induced activation of β‐cells in mouse islets expressing the light‐gated channelrhodopsin‐2 resulted in stimulation of electrical activity in δ‐cells but suppression of α‐cell activity. Activation of the δ‐cells was rapid and sensitive to the gap junction inhibitor carbenoxolone, whereas the effect on electrical activity in α‐cells was blocked by CYN 154806, an antagonist of the somatostatin‐2 receptor. These observations indicate that optogenetic activation of the β‐cells propagates to the δ‐cells via gap junctions, and the consequential stimulation of somatostatin secretion inhibits α‐cell electrical activity by a paracrine mechanism. To explore whether this pathway is important for regulating α‐cell activity and glucagon secretion in human islets, we constructed computational models of human islets. These models had detailed architectures based on human islets and consisted of a collection of >500 α‐, β‐ and δ‐cells. Simulations of these models revealed that this gap junctional/paracrine mechanism accounts for up to 23% of the suppression of glucagon secretion by high glucose.

We used a mouse expressing a light‐sensitive ion channel in β‐cells to understand how α‐cell activity is regulated by β‐cells.

Light activation of β‐cells triggered a suppression of α‐cell activity via gap junction‐dependent activation of δ‐cells.

Mathematical modelling of human islets suggests that 23% of the inhibitory effect of glucose on glucagon secretion is mediated by β‐cells via gap junction‐dependent activation of δ‐cells/somatostatin secretion.

Risk Factors of Recurrence of Diabetic Nephropathy in Renal Transplants

BACKGROUND

Renal transplantation has been established as the treatment of choice for end-stage renal disease (ESRD) due to diabetic nephropathy. This study aimed to investigate the risk factors for recurrence of diabetic nephropathy (RDN) in renal allografts.

METHODS

We studied 1,011 renal transplant patients from 1986 to 2003, of which 95 had ESRD due to diabetic nephropathy. We retrospectively analyzed the clinical characteristics and outcomes of RDN after renal transplantation.

RESULTS

Of the 95 recipients with ESRD due to diabetic nephropathy, 41 developed RDN and 11 of those 41 underwent graft biopsy. The mean durations from transplantation to RDN and to renal replacement therapy was 81.58 months (range, 54-120 mo), and 109.66 months (range, 27-188.4 mo), respectively. At 5 years, treatment on statins and renin-angiotensin-aldosterone system (RAAS) blockers were associated with a higher survival free from RND (82.2% vs 63.2% [P = .070] and 100% vs 80% vs 0.6% [P = .013], respectively). Compared with cyclosporine, tacrolimus was associated with a higher risk for RND (odds ratio [OR], 4.27; 95% confidence interval [CI], 1.75-5.13; P = .047). High doses of prednisone (>0.06 mg/kg) were also associated with a higher risk of RDN (OR, 3.03; 95% CI, 1.19-8.30; P = .029). The combination of calcineurin inhibitor and mammalian target of rapamycin inhibitor (mTORi) demonstrated the highest risk of RDN (OR, 14.08; 95% CI, 3.72-53.29; P < .01).

CONCLUSIONS

Treatment with tacrolimus and mTORi is the most diabetogenic immunosuppressive regimen. Treatment with tacrolimus entails a greater risk of RDN than with cyclosporine. The administration of statins or RAAS blockers could delay the progression of RDN.

En Bloc Multivisceral and Kidney Transplantation in an HIV Patient: First Case Report

The continual improvement in outcome with highly active antiretroviral therapy (HAART) for human immunodeficiency virus (HIV) infection and visceral transplantation for gut failure stimulated our interest in lifting HIV infection as a contraindication for intestinal and multivisceral transplantation. This report is the first to describe visceral transplantation in a patient with HIV infection. A HAART regimen was introduced in the setting of short-gut syndrome with successful suppression of HIV viral load. The indication for en bloc multivisceral and kidney transplantation was end-stage liver failure with portomesenteric venous thrombosis and chronic renal insufficiency. The underlying hepatic pathology was alcoholic and home parenteral nutrition-associated cirrhosis. Surgery was complicated due to technical difficulties with excessive blood loss and long operative time. The complex posttransplant course included multiple exploratory laparotomies due to serious intra-abdominal and systemic infections. Heavy immunosuppression was required to treat recurrent episodes of severe allograft rejection. Posttransplant oral HAART successfully sustained undetectable viral load. Unfortunately, the patient succumbed to sepsis 3 months posttransplant. With new insights into the biology of gut immunity, mechanisms of allograft tolerance, and HIV-associated immune dysregulation, successful outcome is anticipated, particularly in patients who are in need of isolated intestinal and less-organ-contained visceral allografts.

Human induced pluripotent stem cell-derived versus adult cardiomyocytes: an in silico electrophysiological study on effects of ionic current block

Background and Purpose

Two new technologies are likely to revolutionize cardiac safety and drug development: in vitro experiments on human‐induced pluripotent stem cell‐derived cardiomyocytes (hiPSC‐CMs) and in silico human adult ventricular cardiomyocyte (hAdultV‐CM) models. Their combination was recently proposed as a potential replacement for the present hERG‐based QT study for pharmacological safety assessments. Here, we systematically compared in silico the effects of selective ionic current block on hiPSC‐CM and hAdultV‐CM action potentials (APs), to identify similarities/differences and to illustrate the potential of computational models as supportive tools for evaluating new in vitro technologies.

Experimental Approach

In silico AP models of ventricular‐like and atrial‐like hiPSC‐CMs and hAdultV‐CM were used to simulate the main effects of four degrees of block of the main cardiac transmembrane currents.

Key Results

Qualitatively, hiPSC‐CM and hAdultV‐CM APs showed similar responses to current block, consistent with results from experiments. However, quantitatively, hiPSC‐CMs were more sensitive to block of (i) L‐type Ca²⁺ currents due to the overexpression of the Na⁺/Ca²⁺ exchanger (leading to shorter APs) and (ii) the inward rectifier K⁺ current due to reduced repolarization reserve (inducing diastolic potential depolarization and repolarization failure).

Conclusions and Implications

In silico hiPSC‐CMs and hAdultV‐CMs exhibit a similar response to selective current blocks. However, overall hiPSC‐CMs show greater sensitivity to block, which may facilitate in vitro identification of drug‐induced effects. Extrapolation of drug effects from hiPSC‐CM to hAdultV‐CM and pro‐arrhythmic risk assessment can be facilitated by in silico predictions using biophysically‐based computational models.

ECG-based estimation of dispersion of APD restitution as a tool to stratify sotalol-induced arrhythmic risk

Background

Increased spatial dispersion of restitution properties has been associated to arrhythmic risk. An ECG-based index quantifying restitution dispersion, DRest, is evaluated in patients who experienced Torsades de Pointes (TdP) under sotalol challenge and compared with the response in healthy subjects.

Methods and Results

ECG recordings were analyzed for quantification of DRest and QTc, among others biomarkers. DRest provides improved discrimination following sotalol administration between TdP and healthy subjects ([min–max]: [0.18–0.22] vs [0.02–0.12]), compared to other biomarkers including QTc ([436–548 ms] vs [376–467 ms]). Results in healthy subjects are in agreement with simulations of sotalol effects on a human tissue electrophysiological model.

Conclusions

This case study supports the potential of DRest for improved arrhythmia risk stratification even with QTc values below 450 ms.

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Several rate-dependent ECG-based biomarkers were evaluated in three patients who develop Torsades des Pointes after sotalol intake and in twenty five healthy volunteers who do not.

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Dispersion of restitution quantified from the ECG, DRest, identified better drug-induced cardiotoxicity than the conventionally used QTc.

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Neither DRest nor QTc shows sotalol-induced changes in subjects who do not develop TdP.

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Computer simulations corroborate the results of the ECG analysis and suggest that DRest is able to quantify the arrhythmogenic substrate in patients at risk of developing drug-induced arrhythmias.

Expansion of laparoscopic cholecystectomy in a resource limited setting, Mongolia: a 9-year cross-sectional retrospective review

BACKGROUND

The benefits of laparoscopic cholecystectomy have been largely unavailable to most people in developing countries. Mongolia has an extremely high incidence of gallbladder disease. In 2005, only 2% of cholecystectomies were being done laparoscopically. Open cholecystectomies were associated with high rates of wound infections, complications, and increased recovery time. Because of the unacceptable complications associated with open cholecystectomies, and nearly 50% of the nomadic population needing faster post-operative recovery times, a national project for the development of laparoscopic surgery was organised. Multi-institutional collaboration between the Mongolia Health Sciences University, the Dr W C Swanson Family Foundation (SFF), the University of Utah, Intermountain Healthcare, and the Society of American Gastrointestinal and Endoscopic Surgeons (SAGES) led to the promulgation of a formalised countrywide laparoscopic training programme during the past 9 years. This is a retrospective review of the transition from open to laparoscopic cholecystectomy throughout Mongolia.

METHODS

Demographic patient data, diagnosis, and operation preformed-laparoscopic versus open cholecystectomy, between January, 2005, and September, 2013, were collected and trends were analysed from seven regional diagnostic referral and treatment centres, and two tertiary academic medical centres from six of the 21 provinces (Aimags) throughout Mongolia. Data were analysed by individual training centre, by year, and then compared between rural and urban centres.

FINDINGS

Nearly 16 000 cholecystectomies were analysed and compared (4417 [28·2%] men; 11 244 [71·8%] women). Men and women underwent laparoscopic cholecystectomy with the same frequency (41·2% men, 43·2% women) and had similar age (men, mean 52·2 years [SD 14·8]; women, mean 49·4 years [SD 15·7]). By 2013, 62% of gallbladders were removed laparoscopically countrywide as opposed to only 2% in 2005. More than 315 Mongolian practitioners have received laparoscopic training in 19 of 21 Aimags. On average 60% of cholecystectomies are done laparoscopically in urban surgical centres, up from 2%, versus 55% in rural surgical centres, up from 0%, in 2005. Laparoscopic cholecystectomy surpassed open cholecystectomy as the primary method for gallbladder removal countrywide in 2011.

INTERPRETATION

By 2013, 62% of cholecystectomies countrywide were done laparoscopically, a great increase from 9 years ago. Despite being a resource limited country, the expansion of laparoscopic cholecystectomy has transformed the care of biliary tract disease in Mongolia.

FUNDING

The University of Utah Center for Global Surgery.

Examination of type material of two species ofLitomosoides(Filarioidea : Onchocercidae), parasites from bats ; taxonomic consequences

Type material of Litomosoides hamletti Sandground, 1934 from Glossophaga soricina soricina in Brazil and L. penai Jiménez-Quirós & Arroyo, 1960 from Carollia perspicillata azteca in Costa Rica, was examined. The morphology of the spicules shows that these species belong to the carinii group. Their synonymy with L. guiterasi Pérez Vigueras, 1934, from Artibeus jamaicensis yucatanicus in Cuba, does not appear justified because they are distinct in several characters (body length, width of female, size and shape of buccal cavity and capsule, shape of right spicule). L. hamletti is a valid species; L. penai is closely related to it and is considered to be a sub-species, L. hamletti penai Jiménez-Quirós & Arroyo, 1960. The material recovered from Glossophaga spp., previously assigned to L. guiterasi by several authors, is identified as L. h. hamletti. L. guiterasi appears to be closely related to L. chandleri Esslinger, 1973; L. chitwoodi n. sp. (= Litomosoides sp. Chitwood, 1938) seems close to these species; all three are parasites of Artibeus spp.

A multicenter study of sensitization profiles in an allergic pediatric population in an area with high allergen exposure

BACKGROUND AND OBJECTIVE

In areas with a high number of allergens and high allergen concentrations, it is essential to identify the main causes of allergy, especially in pediatric patients. This study was conducted in allergic patients aged 14 or less to identify sensitization profiles during an initial phase, and to then evaluate changes in these profiles after 3 years of follow-up. This article describes the first phase of our investigation.

METHODS

A total of 187 patients aged between 2 and 14 years were included by 5 allergy units; all the children had symptoms suggestive of allergic disease (rhinoconjunctivitis andlor asthma). Allergy diagnosis was confirmed by evaluation of clinical history, allergen exposure, and in vivo or in vitro tests. Specific immunoglobulin E (slgE) to major allergens was tested.

RESULTS

Patients were sensitized to both seasonal (especially grass, olive, cypress and Cynodon dactylon) and perennial allergens (Alternaria alternata) and to panallergens (especially profilin and lipid transfer protein). Almost 60% of the patients included were polysensitized. Sensitization to certain major allergens such as Cup s1, Phl p1, or Sal k1 seems to increase with age. Patients sensitized to profilin had a higher number of sensitizations than non-profilin-sensitized patients. This panallergen is a diagnostic confounding factor.

CONCLUSIONS

A high percentage of allergic pediatric patients living in an area with high exposure levels to a large number of allergens are polysensitized and have a high percentage of sensitization to panallergens. The implementation of new diagnostic tools such as component-resolved diagnosis is crucial.

Effects of recombinant human interleukin 7 on T-cell recovery and thymic output in HIV-infected patients receiving antiretroviral therapy: results of a phase I/IIa randomized, placebo-controlled, multicenter study

BACKGROUND

The immune deficiency of human immunodeficiency virus (HIV) infection is not fully corrected with ARV therapy. Interleukin-7 (IL-7) can boost CD4 T-cell counts, but optimal dosing and mechanisms of cellular increases need to be defined.

METHODS

We performed a randomized placebo-controlled dose escalation (10, 20 and 30 µg/kg) trial of 3 weekly doses of recombinant human IL-7 (rhIL-7) in ARV-treated HIV-infected persons with CD4 T-cell counts between 101 and 400 cells/µL and plasma HIV levels <50 copies/mL. Toxicity, activity and the impact of rhIL-7 on immune reconstitution were monitored.

RESULTS

Doses of rhIL-7 up to 20 µg/kg were well tolerated. CD4 increases of predominantly naive and central memory T cells were brisk (averaging 323 cells/µL at 12 weeks) and durable (up to 1 year). Increased cell cycling and transient increased bcl-2 expression were noted. Expanded cells did not have the characteristics of regulatory or activated T cells. Transient low-level HIV viremia was seen in 6 of 26 treated patients; modest increases in total levels of intracellular HIV DNA were proportional to CD4 T-cell expansions. IL-7 seemed to increase thymic output and tended to improve the T-cell receptor (TCR) repertoire in persons with low TCR diversity.

CONCLUSIONS

Three weekly doses of rhIL-7 at 20 µg/kg are well tolerated and lead to a dose-dependent CD4 T-cell increase and the broadening of TCR diversity in some subjects. These data suggest that this rhIL-7 dose could be advanced in future rhIL-7 clinical studies.

CLINICAL TRIALS REGISTRATION

NCT0047732.