bluuebunny/crossref_metadata_2025_split huggingface dataset:
Inhalation exposure to flavored electronic nicotine delivery systems (vaping) negatively impacts cardiac electrophysiology
Authors: Abou-Assali O , Ebner M , Chams J , Chang M , Zhang Y , Calcul L , Chidipi B , Noujaim S 
Published: May 2024

Abstract

Background
Electronic nicotine delivery systems (ENDS) heat "e-liquids" to generate "e-vapor", an inhalable aerosol. E-liquids contain nicotine and flavors in a solvent of 70% vegetable glycerin, 30% propylene glycol (70VG/30PG). Flavored ENDS are very popular among teens vapers, however, the possible cardiac electrophysiological harm of inhalation exposure to flavored ENDS are not fully understood.

Purpose
To test if inhalation exposure to e-liquids or their constituents compromises mitochondrial integrity, increases oxidative stress, and leads to cardiac electrophysiological toxicity.

Methods
Gas chromatography mass spectrometry (GC/MS), and flow cytometry, in-vivo programmed electrical stimulation (PES), and transmission electron microscopy (TEM) were used in atrial like HL-1 myocytes and in mice overexpressing the antioxidant mitochondrial catalase (MCAT) which underwent inhalation exposure to e-vapor.

Results
We compared the toxicity of e-vapor exposure to 30 differently flavored e-liquids (70VG/30PG, with 6 mg/ml nicotine) in HL-1 cells using annexinV flow cytometry. Most e-liquids were toxic. We then quantified the concentrations of major flavoring carbonyls (cinnamaldehyde, vanillin, ethyl-vanillin, maltol, and ethyl-maltol) in the 30 e-liquids using GC/MS. Toxicity of the e-liquids in HL-1 cells correlated with their flavoring carbonyls concentration. We assessed oxidative stress (OS) via CellROX flow cytometry in HL-1 cells exposed to vanilla flavored e-vapor. OS increased in exposed cells but this was blunted by N-acetylcycteine pretreatment. In-vivo inhalation exposure to e-vapor of vanilla flavored e-liquid with 6 mg/ml nicotine increased inducible ventricular tachycardia duration in WT but not in MCAT mice versus control. In TEM, mitochondrial perimeter was unaffected, but cristae thickness decreased in exposed WT, but not in exposed MCAT hearts versus controls. We then investigated whether adverse cardiac effects of vaping are due only to nicotine. Mice were exposed to the e-vapor of 70VG/30PG base alone or base plus vanillin WITHOUT nicotine. In telemetric ECG analysis of heart rate variability, exposure to base plus vanillin decreased parasympathetic indices more than exposure to base alone. In PES, the effective refractory periods of base alone and base plus vanillin groups tended to be shortened vs air controls. While exposure to base alone and to base plus vanillin significantly increased inducible ventricular tachycardia duration compared to air controls, the increase in the base plus vanillin group was more significant compared to that of base alone.

Conclusions
Inhalation exposure to flavored ENDS or to their NON-NICOTINE constituents negatively affects ventricular electrophysiology, possibly via adverse mitochondrial remodeling, and increased oxidative stress.
A new hiPSC-based viral expression system to study virus host-cell interaction in hiPSC-derived cardiomyocytes
Authors: Peischard S , Strutz-Seebohm N , Seebohm G 
Published: May 2024

Abstract
Coxsackievirus B3 (CVB3) belongs to the Picornaviridae family and is a member of the enterovirus genus. CVB3 is the most frequently detected pathogen in viral myocarditis, which leads to acute heart infections in 20-40% of cases and to dilated cardiomyopathy (DCM) in cases of prolonged viral persistence. Complex arrhythmias and sudden deaths due to CVB infections have also been reported, particularly in newborns and children. Observed arrhythmias include bradycardia, AV block and junctional ectopic tachycardia, suggesting that in addition to the functioning myocardium, the pacemaker cells and cardiac conduction system may also be impaired by CVB3 infection. The symptomatic phenotype is highly variable and depends on unclear host factors. It ranges from inconspicuous inflammation and rapid healing to acute congestive heart failure or viral persistence with progressive chronic disease. Despite the increasing and profound knowledge about viral myocarditis, it is still a challenge to identify further host factors that contribute to acute and chronic myocarditis, as science lacks sensitive and controllable disease models. The presented project shows the generation of a controlled, inducible virus-expressing hiPSC line that provides a solution for the beforementioned problems. The new human induced pluripotent stem cell line (hiPSC) i can be used to carry out virologic experiments in a controlled manner and without risk to the user. For this purpose, the modified and non-infectious genome of the enterovirus Coxsackievirus B3 (CVB3) is stably integrated into the genome of a wild-type hiPSC line. The CVB3 genome to be stably integrated was modified to prevent the formation of functional capsids by a DVP0 mutation. In addition, the 3'UTR and 5'UTR regions of the CVB3 genome were removed, which prevents uncontrolled self-replication of viral RNA. As a result, work with this CVB3DVP0-UTR genome is classified as S1 compliant. The expression of the CVB3DP0-UTR virus genome can be controlled by adding doxycycline to the cell culture medium by a TeT-On System. The transfected cells are then cultivated as clones and tested for virus expression. The dose-dependent CVB3DVP0 expression is verified using qPCR and FACS after 1 day of doxycycline application in the cell culture medium. Clones isolated and positively tested for CVB3 expression are used to carry out initial experiments on the interaction of the expressed viral proteins with the cell. Particular focus is placed on the induction of cell death, remodelling of the cytoskeleton and increase of reactive oxygen species (ROS) in mitochondria after CVB3DVP0-UTR induction in order to validate the cell system for application. Differentiation of the CVB3-expressing hiPSC-line into cardiomyocytes with subsequent virus induction results in the elevation of mitochondrial ROS, degradation of the cytoskeleton and arrhythmic behaviour of the cells.
The entrainment of action potential duration and contraction amplitude by recapitulation of respiratory sinus arrhythmia in isolated cardiac myocytes
Authors: Carpenter A , Pannell L M K , Fowler E D , Butler A S , Paton J F R , Hancox J C , James A F 
Published: May 2024

Abstract

Introduction
Respiratory sinus arrhythmia (RSA) is the oscillation of heart rate in phase with ventilation and represents the high frequency component of heart rate variability. RSA is prevalent in the young and the endurance-trained and its loss is considered a prognostic indicator for sudden cardiac death. The recapitulation of RSA improves cardiac function in animal models of heart failure1,2. However, the precise mechanisms by which RSA affects cardiac function are unknown.
Hypothesis: We examined the hypothesis that the recapitulation of RSA in isolated ventricular myocytes affects the stimulus interval-dependence of action potential duration (APD) and sarcomere shortening through mechanisms involving sarcoplasmic reticulum (SR) Ca2+ release.

Methods
Hearts were excised from adult male guinea pigs under general anaesthesia (140 mg/kg bodyweight euthatal, i.p.) and left ventricular myocytes isolated. Isolated myocytes were superfused with Tyrode’s solution for perforated patch whole-cell current clamp recording and action potentials and sarcomere length measured simultaneously. Sample sizes are presented as n/N (cell/animal number) and nested hierarchical analysis applied using a generalized linear mixed model (P&lt;0.05).

Results
Pacing at a basic cycle length (CL, 350 ms) induced APD, Ca2+ transient amplitude (CaT) and sarcomere shortening alternans. The recapitulation of RSA through oscillatory pacing (OP), in which CL was set to 20% below and 20% above the corresponding basic CL in a 2-short, 2-long stimulus train, reduced the incidence of alternans. Furthermore, OP entrained APD, CaT and sarcomere shortening and this entrainment persisted in voltage clamp experiments with fixed APD. Using a three-step protocol to examine the dependence of APD and sarcomere shortening on both preceding (CLn-1) and anteceding (CLn-2) stimulus intervals, both APD and sarcomere shortening were found to depend directly on the preceding cycle length (CLn-1, P&lt;0.001). In contrast, sarcomere shortening depended inversely on the anteceding CL (CLn-2, P&lt;0.001; n/N = 24/4). Following treatment of the cells with caffeine (50 µM) to sensitise ryanodine receptors, the dependence of APD and sarcomere shortening on CLn-1 was markedly suppressed, and the inverse dependence of sarcomere shortening on CLn-2 was lost (P&lt;0.001, n/N = 6/3). The effects of OP are akin to post-extrasystolic potentiation3 and mathematical simulation4 supports the involvement of changes in the sarcoplasmic reticulum Ca2+ content.

Conclusion
These data are consistent with an obligatory role for the SR in the entrainment of APD, CaT and sarcomere shortening and the suppression of alternans by the recapitulation of RSA. We hypothesise that recapitulation of RSA would be protective against ventricular tachyarrhythmia and further work is required to test this.
Right atrial endomysial fibrosis is associated with higher POAF-burden
Authors: Winters J , Kawczynski M J , Gilbers M D , Isaacs A , Zeemering S , Bidar E , Maesen B , Verheule S , Schotten U 
Published: May 2024

Abstract

Background
Atrial endomysial fibrosis, rather than overall connective tissue content, determines the complexity of conduction in human atrial fibrillation (AF). Moreover, the AF-specific blood biomarker BMP10 is associated with atrial endomysial fibrosis, but not overall connective tissue content. It is unclear whether pre-operative atrial endomysial fibrosis predicts post-operative AF (POAF) incidence and burden.

Objective
To determine the predictive value of atrial fibrosis for early and late POAF burden.

Methods
Patients with and without AF history were included in the RACE V tissue bank study (n=134). Post-operative rhythm was monitored continuously for 2.5 years with implantable loop recorders. Late POAF-burden was investigated following a 90-day blanking period. Left (n=89) and/or right (n=92) atrial appendage biopsies (LAA/RAA) were snap-frozen and histologically investigated following WGA-staining.

Results
Logistic regression, corrected for age, sex and AF history, showed that left (st.β = 0.54 [0.23-0.85], p=0.001) and right (st.β=0.35 [0.07-0.64], p=0.017) atrial endomysial fibrosis were associated with early POAF burden in the blanking period. Only right atrial endomysial fibrosis, however, predicted late POAF-burden (st.β=0.44 [-], p=0.009). Adjusted Cox proportional hazards analyses indicated that patients in the highest tertile of right atrial endomysial fibrosis, in particular, are at risk for late POAF (HR T3 vs T1: 2.47 [1.18-5.17], p=0.016, Fig 1). Overall connective tissue content in both atria was not associated with POAF-burden.

Conclusion
Patients with higher levels of right atrial endomysial fibrosis are at risk for developing late POAF with a higher POAF-burden.Figure 1
Bioenergetics and mitochondrial deregulation underlie self-sustained persistency of atrial fibrillation in an ovine model
Authors: Caluori G , Nattel S , Vaillant F , Charron S , Naud P , Guilloteau F , Claverol S , Abell E , Loyer V , Constantin M , Popa M A , Bernus O , Jais P , Dos Santos P , Pasdois P 
Published: May 2024

Abstract

Background
Atrial fibrillation (AF) often transitions from paroxysmal to more sustained forms in a 4-15/100 person-year range(1). It is well-recognized from both clinical and animal studies that some individuals undergo this transition much more readily than others, but the underlying mechanisms remain unclear.

Purpose
To identify potential differences in atrial bioenergetics between animals developing stable AF (AF-S) versus those resistant to this transition (AF-R) in a sheep AF-model.

Methods
AF was induced through repeated bursts of atrial tachystimulation (2). Stability of AF was monitored with telemetry. In-vivo electrophysiological remodeling was assessed via contact mapping. Metabolic and bioenergetic remodeling were evaluated using frozen left atrial appendage (LAA) tissues and isolated LAA mitochondria.

Results
AF-S sheep developed stable (&gt;24-hour self-sustained) AF after 13 (range 5-22) days on average, whereas AF-R sheep failed to develop stable AF despite 120-day tachystimulation. Contact mapping and histological analysis revealed similar electro-anatomical remodeling in AF-S and AF-R groups, with the only significant difference observed in the decrease of activation time and conduction velocity in the AF-S atria. Both AF-S and AF-R animals displayed a notable increase in mitochondrial mass. Proteomic analysis showed significant differences in metabolism-related proteins and pathways between AF-S and AF-R, in particular concerning the anaplerotic supplementation of the tricarboxylic acid cycle at the level of α-ketoglutarate. Furthermore, compared to AF-R, AF-S LAA exhibited a 45% increase in succinate content, and a 23% decrease in ATP and Creatine Phosphate (PCr) content, suggesting a pathological metabolic alteration linked to a bioenergetic default. AF-S mitochondria presented abnormal succinate-oxidation, associated with a significant 20% decrease in ATP-synthesis rate, 22% increase in ROS-production, mitochondrial-membrane hyperpolarization, and decreased Complex I/II specific activity ratio. AF-S mitochondria alterations were prevented by complex I inhibitor S1QEL1.1, hinting to a participation of mitochondrial ROS into the mechanism of AF stabilization. In vivo acute intravenous perfusion of succinate in rats made them more susceptible to more frequent (OR 35 CI=[1.63-449.80]) and longer AF episodes upon treansesophageal stimulation; this vulnerability to AF was prevented by intraperitoneal pretreatment with SQEL1.1.

Conclusions
Resistance to AF-stabilization is associated with specific bioenergetic remodeling. These findings provide new mechanistic insights into AF-resistance and might open avenues for novel therapeutic strategies for AF-management.
In vivo KCNH2-suppression-replacement gene therapy attenuates the pathogenic phenotype in transgenic rabbits with short QT syndrome type 1
Authors: Nimani S , Bains S , Alerni N , Giammarino L , Louradour J , Horvath A , Beslac O , Tester D J , Christoforou N , Brunner M , Casoni D , Haeberlin A , Brooks G , Ackerman M J , Odening K E 
Published: May 2024

Abstract

Background
Short QT syndrome type 1 (SQT1) is a genetic channelopathy characterized by gain-of-function variants in the KCNH2-encoded potassium channel underlying the IKr current, leading to a pathologically shortened cardiac action potential duration (APD). Patients with SQT1 manifest shortening of the QT duration on 12-lead ECG and are prone to cardiac arrhythmias that can culminate in sudden cardiac death.

Purpose
To investigate the effect of a KCNH2-specific suppression-replacement (KCNH2-SupRep) gene therapy on the pathogenic phenotype in transgenic SQT1 rabbits.

Methods
A novel dual-component KCNH2-SupRep gene therapy was developed by combining a custom-designed KCNH2 shRNA (suppression) and an shRNA-immune (shIMM) KCNH2 cDNA (replacement) into AAV9. In vivo AAV9-mediated KCNH2-SupRep / sham treatment was performed by intra-aortic root injection of the KCNH2-SupRep AAV9 (1E10 vg/kg) / NaCl 0.9% during balloon occlusion using a Swan Ganz catheter. Three weeks after administration, 12-lead ECGs were assessed in adult transgenic SQT1 (KCNH2-N588K, gain of IKr due to impaired inactivation) and wild-type (WT) rabbits to determine the effect of KCNH2-SupRep / sham treatment on the rabbit’s QTc duration and QT index. Patch-clamp recordings were performed in isolated ventricular cardiomyocytes (CMs) to evaluate the effect of KCNH2-SupRep / sham treatment on the CM’s action potential duration at 90% repolarization (APD90).

Results
After in vivo AAV9-mediated KCNH2-SupRep gene therapy injection (1E10 vg/kg) in 7 SQT1 rabbits, QTc duration and QT index significantly increased in all SQT1 rabbits (QTc: untreated(UT)-SQT1: 153.2±3.8ms vs treated-SQT1: 166.5±4.6ms, p=0.0002, N=7 each; QTi: UT-SQT1: 92.5±1.9% vs treated-SQT1: 99.7±2.7%, p=0.0007, N=7 each), reaching a QT index of ~100% typically observed in WT rabbits. No such changes were observed in the sham-SQT1 rabbits. Furthermore, cardiomyocytes isolated from 7 SQT1 rabbits that received in vivo SupRep gene therapy demonstrated APD90 prolongation closer to WT rabbits compared to UT-SQT1 and sham-SQT1 rabbits (APD90: UT-SQT1: 314.2±11.9ms, WT: 404.5±13.8ms, treated-SQT1: 362.9±10.6ms; UT-SQT1 vs WT: p&lt;0.0001; UT-SQT1 vs treated-SQT1: p=0.019; WT vs Treated-SQT1: p=0.031). In line with these observations, first IKr measurements demonstrate smaller IKr currents in SupRep-SQT1 than in sham-SQT1 CMs.

Conclusion
In vivo KCNH2-SupRep gene therapy normalizes the pathologically shortened QTc duration and QT index in transgenic SQT1 rabbits. Moreover, KCNH2-SupRep treatment prolongs APD90 in SQT1 compared to UT-SQT1 and sham-SQT1 reaching levels closer to WT.
Angiotensin II-mediated oxidative stress increased the vulnerability of ventricular arrhythmia in cardiac hypertrophy rabbit model, which is suppressed by CaMKII inhibitor
Authors: Lee Y , Bae H J , Shin D G , Jung B C 
Published: May 2024

Abstract

Objectives
Angiotensin system is a major cause of heart failure and arrhythmia. Despite a lack of direct evidence that oxidative stress causes ventricular arrhythmia, reversal of oxidative stress is considered a plausible therapy. This study evaluated the Ca2+/calmodulin-dependent protein kinase II (CaMKII) inhibitor could suppress arrhythmia in cardiac hypertrophy rabbit model.

Methods
Angiotensin II (Ang II) or saline was administrated for 2 weeks via osmotic minipumps implanted subcutaneously in the midclavicular region. Hearts were perfused, mapped optically to analyze action potential durations (APD), and restitution kinetics, and tested for VF vulnerability. The intracellular calcium dynamics were measured in cardiomyocyte treated with Ang II (10 ng/ml) for 1 hours.

Results
In Ang II rabbit groups, 2(30%) rabbits died and had ventricular arrhythmia and hearts had enlarged left ventricle, longer APD90, slower conduction velocity (CV; P&lt;0.01 versus control) and higher levels of transcripts for CaMKII, PLB, RyR2 (P&lt;0.05 versus control). N-acetylcysteine treatment reversed the transcripts for APD90 and CV (P&lt;0.01). Programmed stimulation triggered VF in Ang II (n=5/6) and Ang II + saline (n=4/6), but not in control (n=0/10, P&lt;0.01). Cardiomyocyte induced with Ang II showed increased spontaneous Ca2+ release (Ca2+ Wave Frequency; 1.0±0.0 vs. 5.1±0.5, p=0.001, Ca2+ Amplitude; 1.0±0.0 vs. 1.3±0.1, p=0.001) with control. CaMKII inhibitor reversed the change of Ca2+.

Conclusion
The Ang II group had an increased incidence of arrhythmia caused by increased phosphorylation of Ca2+ handling proteins. These changes were partially reversed by CaMKII inhibition.
Genetic characterization of drug-induced long QT syndrome in a large prospective cohort
Authors: Campos Garcia B , Rodriguez Santiago B , Salazar Blanco J , Hernandez Ontiveros H , Avila Parcet A , Garcia Hernando V , Carceller Sindreu M , Juanes Borrego A , Rodriguez Font E , Alonso Martin C , Mendez Zurita F , Moreno Weidmann Z , Vinolas Prat X , Guerra Ramos J M 
Published: May 2024

Abstract

Introduction
Drug-induced long QT syndrome (DI-LQTS) is a clinical entity with a poorly defined etiopathogenesis.

Purpose
The objective of the study was to determine the genetic basis of a prospective cohort of patients with DI-LQTS in the setting of a tertiary hospital center.

Methods
Prospective observational study with consecutive inclusion of patients with the diagnosis of DI-LQTS according to standard criteria, in a tertiary hospital, between 2018 and 2022. A genetic study was performed through massive DNA sequencing to identify variants in known genes associated with cardiopathy, arrhythmogenic and cardiomyopathy.

Results
86 patients (age 65±15 years, 59% men) were included. The mean corrected QT interval (QTc) of the entire cohort was 543±56 ms. The drugs associated with QTc interval prolongation were: psychotropics 51%, antiarrhythmics 38%, anesthetics 30%, antibiotics 16%, antineoplastics 5%, others 4%. Twenty-one patients (24%) presented with ventricular arrhythmias at the time of drug-induced QTc prolongation: 10 (12%) ventricular fibrillation, 7 (8%) sustained ventricular tachycardia, 3 (3%) non-sustained ventricular tachycardia, 1 (1%) frequent ventricular premature beats.
Genetic information was obtained in 83 (97%) patients. 17 pathogenic mutations associated with heart disease were identified in 15 (18%) patients: 4 (5%) patients with 5 mutations in ion channel genes (KCNE1, KCNE1B, KCNH2, RYR1, RYR2), and 12 (14%) patients with 12 mutations in genes associated with cardiomyopathy (NF1, PKD2, ABCC6, TTN, FHOD3, MYO6, COL11A1, CCDC40, CRELD1, COL4A1). Two patients had 2 pathogenic mutations each, one of them with both mutations associated with channelopathy, and another with a mutation associated with channelopathy and a second mutation related to cardiomyopathy. Only 1 patient carrying a pathogenic mutation related to cardiomyopathy had a clear phenotype, while in 3 carrier patients there was a history of transient systolic dysfunction, 2 due to tachycardiocardiopathy and 1 due to peripartum cardiomyopathy. The identification of a pathogenic mutation was not related to significant differences in QTc interval prolongation (544±63 vs 542±55 ms) or risk of ventricular arrhythmias (26% vs 24%).

Conclusions
The genetic basis of drug-induced long QT syndrome is essentially different from that of the congenital form of the disease. The identification of pathogenic mutations in genes associated with cardiomyopathy is relatively frequent, while those associated with ion channel genes are uncommon.