Pathological Hearts Research Articles

Supersulfide catabolism participates in maladaptive remodeling of cardiac cells

The atrophic myocardium resulting from mechanical unloading and nutritional deprivation is considered crucial as maladaptive remodeling directly associated with heart failure, as well as interstitial fibrosis. Conversely, myocardial hypertrophy resulting from hemodynamic loading is perceived as compensatory stress adaptation. We previously reported the abundant presence of highly redox-active polysulfide molecules, termed supersulfide, with two or more sulfur atoms catenated in normal hearts, and the supersulfide catabolism in pathologic hearts after myocardial infarction correlated with worsened prognosis of heart failure. However, the impact of supersulfide on myocardial remodeling remains unclear. Here, we investigated the involvement of supersulfide metabolism in cardiomyocyte remodeling, using a model of adenosine 5′-triphosphate (ATP) receptor-stimulated atrophy and endothelin-1 receptor-stimulated hypertrophy in neonatal rat cardiomyocytes. Results revealed contrasting changes in intracellular supersulfide and its catabolite, hydrogen sulfide (H2S), between cardiomyocyte atrophy and hypertrophy. Stimulation of cardiomyocytes with ATP decreased supersulfide activity, while H2S accumulation itself did not affect cardiomyocyte atrophy. This supersulfide catabolism was also involved in myofibroblast formation of neonatal rat cardiac fibroblasts. Thus, unraveling supersulfide metabolism during myocardial remodeling may lead to the development of novel therapeutic strategies to improve heart failure.

Traitement médico-judiciaire de la mort subite inattendue du sujet jeune à Toulouse : bilan des pratiques avant mise en place d’un protocole

IntroductionSudden death of adults is a natural death occurring within the hour from the onset of symptoms. It may be of cardiac origin and, in young people, there may be a genetic origin which requires family screening to prevent further deaths. These events justify the forensic institutes investigations on requisition. The aim of this study was to assess the practices of the Toulouse forensic medicine department in order to evaluate the management of these victims. Material and methodsThe autopsy reports of subjects under 45 years old, carried out between 01/01/2012 and 31/12/2021, were extracted from the database of the forensic medicine department. Only subjects who were not putrefied, not drug addicts and whose causes of death were unexplained or of cardiac origin, were retained. Subjects with ischaemic heart disease were excluded. Epidemiological and autopsy data, as well as the results of toxicological, anatomopathological and genetic analysis were collected and analysed. ResultsOf the 5947 forensic autopsies performed in this period, 164 individuals were included. The population was predominantly male (71%), with an average age of 32±8.5 years. The medical history was mainly psychiatric (17%) or cardiovascular (11.6%). Death occurred in the majority of cases at home (67%). Half of our population was obese or overweight. At autopsy, 52% of the hearts were normal. In 25% of cases, cardiomegaly was found. Toxicological and anatomopathological tests were almost always made, but they were only analysed in 74% and 63% of cases respectively. Genetic tests were taken in only 30% of cases and less than one-third of them were analysed. The results of the toxicological analysis could be recovered in 78% of cases and showed that more than 1/3 of the subjects had a lethal dose of at least one toxic substance. At the anatomopathological analysis, a majority of the hearts were normal and only 35% of the macroscopically pathological hearts had microscopic lesions. Genetic analysis results could only be retrieved in 3 cases and only one patient had a mutation. ConclusionOur retrospective study shows that toxicological and anatomopathological investigations are insufficiently performed in cases of sudden death in young people. However, a non-negligible proportion of these subjects die from a toxic cause. Genetic tests and analysis are very inadequate. An improvement in practices with the systematic tests and their analysis is therefore advisable.

Characteristics of aortic and pulmonary valve cusp fenestrations in healthy hearts

Fenestrations in semilunar valves of human hearts have been incidentally described during autopsies since the 1800s, and were thought to be a degenerative process of the valve cusps. Due to the nature of autopsy, prior literature has primarily examined these fenestrations in pathologic hearts, and has implicated them in leading to valve insufficiency, regurgitation, and cusp rupture. More recent studies have predicted an increase in fenestration prevalence in the rapidly aging United States and have warned of a potential increase in fenestration-related valvular pathology. Herein, we analyze fenestration prevalence in 403 healthy human hearts and report findings that differ from these prior reports, and emphasize that fenestrations may not necessarily portend significant valvular dysfunction.

PO-01-143 HYPOTHERMIA-INDUCED J-WAVES AND ARRHYTHMIAS ARE ASSOCIATED WITH AN EXACERBATION OF REPOLARIZATION RATHER THAN CONDUCTION HETEROGENEITY IN HUMAN HEARTS

The cardiac effects of hypothermia have been studied for many years since the initial discovery of the electrocardiographic J-wave in a case of accidental hypothermia. However, the precise mechanisms underlying the origin of the hypothermic J-wave and associated arrhythmias in man are still debated. A limited number of ex vivo animal studies have focused on the transmural repolarization dispersion, but do not provide global mapping of ventricular activation and repolarization heterogeneities. To map hypothermia-induced electrophysiological changes at a tissue level and study the mechanisms of initiation and maintenance of arrhythmias. Optical mapping experiments were performed on isolated right ventricles (RV) from pigs (N=7) and humans obtained through our organ donation program (N=3 control subjects; N=1 SCN5A BrS-associated mutant subject). Epi- and endocardial (EPI and ENDO) action potential conduction and repolarization properties were assessed at different pacing frequencies and arrhythmias were mapped and quantified at baseline (37°C), during severe hypothermia (29°C), and after a return to normothermia. Hypothermia induced a reversible prolongation of global action potential duration at 80% of repolarization (APD80) in pigs (EPI: +27%, ENDO: +21%; p<0.01) and humans (+45% in both EPI and ENDO), an increase in APD80 dispersion, and steepness of APD restitution curve. Repolarization time dispersion was increased in both species (pigs: +94%, p<0.001 in EPI and +79%, p<0.05 in ENDO; humans: +97% in EPI and +14% in ENDO). The total activation time was significantly prolonged in pigs (EPI: +58%, p<0.001; ENDO: +46%, p<0.01) but not in humans. Arrhythmogenicity was further increased in human ventricles (+43% of spontaneous arrhythmias in pigs versus +100% in humans), which always displayed defibrillation-resistant arrhythmias. In the carrier of a SCN5A mutant, hypothermia additionally potentiated epicardial localized conductive disorders already detected at baseline. Our results indicate that, in humans, and contrary to pigs, the hypothermic J-wave and associated arrhythmogenesis result more from an exacerbation of repolarization rather than conduction heterogeneity. Pre-existing localized conduction heterogeneities within pathological hearts can however contribute to the J-wave phenotype during hypothermia.

PO-02-246 PPARΓ ACTIVATION MEDIATES CARDIAC PATHOLOGIES IN TWO MOUSE MODELS OF ARRHYTHMOGENIC CARDIOMYOPATHY (ACM) AND ITS THERAPEUTIC IMPLICATIONS

Using ACM patient-specific induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs), we showed that abnormal peroxisome proliferator-activated receptor-gamma (PPARγ) activation on normal adult PPARα-mediated metabolic backgrounds in CMs resulted in pathological hallmarks of ACM. PPARγ inhibitors rescue all ACM pathologies effects (Nature 2013) but may carry systemic side effects. Here, we study the pathogenic role of PPARγ activation in 2 ACM mouse models and test therapeutic potentials of 2 angiotensin II-receptor blockers (ARBs) commonly used to treat cardiomyopathies: Valsartan and Losartan. Valsartan has minimal activity yet Losartan has strong activity for PPARγ gene activation, respectively. We used 2 established ACM mouse models in this study: 1) mice with tamoxifen (TAM)-inducible and CM-specific (by αγMHC-Cre) double knockout (DKO) of plakoglobin (JUP) and βcatenin (MCB 2012) that developed ACM pathologies at 2-3 months only after TAM injection; and 2) mice with CM-specific and homozygous knockout of JUP (JUP KO, Hum Mol Genet 2011) that develop ACM pathologies rapidly in 1-2 months after birth. Feeding DKO mice with 0.1 mg/ml rosiglitazone (Rosi, a PPARγ activator) for 2 weeks (wks) after TAM injection accelerated the decrease in left ventricular ejection fraction (LV EF) (from 67.4% to 27.1%) within 2-3 weeks after feeding Rosi. For JUP KO mice at 8-9 wks after birth, the pathological hearts showed hyperactivated PPARγ (at both mRNA and protein levels) and elevated apoptotic gene expressions (3-fold increases in caspase 3 and BAX/BCL2 ratios). Feeding both ACM mouse models with 0.2 mg/ml Valsartan for 6 wks reduced PPARγ proteins and apoptotic genes (BAX/BCL2 ratios) by 2-3 folds. In JUP KO mice, Valsartan prevented LV EF deterioration yet losartan at equivalent doses led to early death and reduced LV EF. Our study results support strongly that abnormal PPARγ activation in ACM CMs plays a key pathogenic role in both human iPSC-CM-based and 2 mouse models of ACM. An ARB with PPARγ agnostic activities can worsen ACM pathologies and only ARB with minimal PPARγ agonistic activity can prevent ACM disease progression. These results have significant implications in avoiding using any drug with PPARγ agnostic activities to treat human ACM.

Cardiac-derived extracellular matrix: A decellularization protocol for heart regeneration.

Extracellular matrix (ECM) is a fundamental component of the heart, guiding vital cellular processes during organ homeostasis. Most cardiovascular diseases lead to a remarkable remodeling of the ECM, accompanied by the formation of a fibrotic tissue that heavily compromises the heart function. Effective therapies for managing fibrosis and promoting physiological ECM repair are not yet available. The production of a decellularized extracellular matrix (d-ECM) serving as a three-dimensional and bioactive scaffold able to modulate cellular behavior and activities is considered crucial to achieve a successful regeneration. The protocol represents a step-by-step method to obtain a decellularized cardiac matrix through the combination of sodium dodecyl sulphate (SDS) and Triton X-100. Briefly, cardiac samples obtained from left ventricles of explanted, pathological human hearts were dissected and washed to remove residual body fluids. Samples were then snap-frozen and sliced by a cryostat into 350 μm thick sections. The sections obtained were decellularized using a solution containing 1% Triton X-100 and 1% SDS in combination, for 24 hours, until observing the color change from brownish-red to translucent-white. As a result, the protocol shows efficiency in preserving ECM architecture and protein composition during the whole process, suggesting that it is worthwhile, highly reproducible and produces a well- preserved decellularized extracellular matrix from cardiac samples. Notwithstanding, some limitations need to be addressed, such as the risk for microbial contamination and the unpredictable trend of the protocol when applied to decellularize samples other than myocardium, vessels, or skin. These issues require antibiotics mixture supplement during the procedure followed by UV sterilization, and appropriate adjustments for a tissue-specific utilization, respectively. The protocol is intended to produce a cardiac d-ECM for cell settlement, representing the ideal scaffold for tissue engineering purposes.

Overexpression of cardiac‐specific IGF‐IIRα accelerates the development of liver dysfunction through STZ‐induced diabetic hepatocyte damage in transgenic rats

This study reports the effect of cardiac-specific insulin-like growth factor-II receptor α (IGF-IIRα) overexpression on the development of liver dysfunction in transgenic rats via STZ-induced diabetic hepatocyte damage. The cardio-hepatic syndrome comprises a number of heart and liver illnesses in which an acute or chronic disease in one organ can lead to acute or chronic disease in the other. However, the molecular mechanism involved in such a set of conditions is unclear. In this study, we developed a transgenic rat model with cardiac-specific overexpression of IGF-IIRα, which is a supplementary splicing variant of insulin-like growth factor-II receptor (IGF-IIR), expressed in pathological hearts, to investigate the relationship between late fetal gene expression in diabetic hearts and their influence on diabetic hepatopathy. STZ (55 mg/kg) was intraperitoneally delivered into IGF-IIR overexpressed transgenic (TG) and non-transgenic (NTG) animal models developed in Sprague-Dawley (SD) rats after an overnight fast. The relationship among IGF-IIRα overexpression and hepatocyte damages have been determined based on the complexity of damage in the liver. Our findings revealed that overexpression of the cardiac-specific IGF-IIRα enhances diabetes-induced morphological alterations and hepatic inflammation in the livers. The diabetic transgenic rats demonstrated the development of pathological conditions such as thick collagen fiber deposition, bridging fibrosis, and elevation of α-SMA and MMP1 related liver fibrosis mechanisms. Our data suggest that IGF-IIRα overexpression in the heart during a pathological state may worsen diabetic hepatopathy in rats.

Abstract P3097: Post-transcriptional Mechanisms Of FTO-regulated Cardiac Contractility

Background: N6-methyladenosine (m6A), the most abundant and functionally relevant mRNA modification, is reversibly demethylated by FTO, an m6A eraser and a primary regulator of m6A in the heart. In failing hearts, decreased FTO increases m6A, critically reducing cardiomyocyte contraction. FTO overexpression improved cardiac contraction and attenuated remodeling. Here, we investigate post-transcriptional and translational mechanisms of FTO-regulation of cardiomyocyte contraction in vitro and in vivo. We hypothesize that FTO directly binds to selective cardiac contractile mRNAs at their m6A site and affects their nuclear export, polysome binding, cytoplasmic availability, and protein expression. Methods and Results: We performed immunostaining to examine the intracellular location and expression of FTO under different pathological stimuli in human ventricular cardiomyocyte cell line (AC16 cells), rat primary cardiomyocytes and mouse and human hearts. FTO was detected in both cytoplasmic and nuclear compartments, and was significantly reduced in pathological hearts compared to healthy controls. MeRIP (immunoprecipitation of m6A-RNA) sequencing analysis uncovered that FTO targets different sets of cardiac mRNAs in the cytoplasm and nucleus of cardiomyocytes. Knocking down FTO increased nuclear retention of cardiac mRNAs, which was reversed with FTO overexpression. Immunoprecipitation experiments demonstrated that FTO directly binds to cardiac mRNAs. To determine the effect of FTO on translation of select cardiac mRNAs, we isolated the polysome fraction from the cytoplasm of AC16 cells. Interestingly, our stable isotope labeling with amino acids in cell culture (SILAC) and mass spectrometry analyses suggested increased expression of cardiac contractile proteins with FTO overexpression. Conclusion: We demonstrate that FTO positively regulates post-transcriptional nuclear export, polysome binding of cardiac contractile mRNAs, and regulates their translation under pathological stimuli. By combining experimental and predictive models in human and mice, we have characterized the transcriptome-proteome molecular interplay regulating cardiac function.

Embedded Computational Heart Model for External Ventricular Assist Device Investigations

PurposeExternal cardiac assist devices are based on a promising and simple concept for treating heart failure, but they are surprisingly difficult to design. Thus, a structured approach combining experiments with computer-based optimization is essential. The latter provides the motivation for the work presented in this paper.MethodsWe present a computational modeling framework for realistic representation of the heart’s tissue structure, electrophysiology and actuation. The passive heart tissue is described by a nonlinear anisotropic material law, considering fiber and sheetlet directions. For muscle contraction, an orthotropic active-strain model is employed, initiated by a periodically propagating electrical potential. The model allows for boundary conditions at the epicardium accounting for external assist devices, and it is coupled to a circulation network providing appropriate pressure boundary conditions inside the ventricles.ResultsSimulated results from an unsupported healthy and a pathological heart model are presented and reproduce accurate deformations compared to phenomenological measurements. Moreover, cardiac output and ventricular pressure signals are in good agreement too. By investigating the impact of applying an exemplary external actuation to the pathological heart model, it shows that cardiac patches can restore a healthy blood flow.ConclusionWe demonstrate that the devised computational modeling framework is capable of predicting characteristic trends (e.g. apex shortening, wall thickening and apex twisting) of a healthy heart, and that it can be used to study pathological hearts and external activation thereof.

Heat Shock Protein 22 in Physiological and Pathological Hearts: Small Molecule, Large Potentials.

Small heat shock protein 22 (HSP22) belongs to the superfamily of heat shock proteins and is predominantly expressed in the heart, brain, skeletal muscle, and different types of cancers. It has been found that HSP22 is involved in variant cellular functions in cardiomyocytes and plays a vital role in cardiac protection against cardiomyocyte injury under diverse stress. This review summarizes the multiple functions of HSP22 in the heart and the underlying molecular mechanisms through modulating gene transcription, post-translational modification, subcellular translocation of its interacting proteins, and protein degradation, facilitating mitochondrial function, cardiac metabolism, autophagy, and ROS production and antiapoptotic effect. We also discuss the association of HSP22 in cardiac pathologies, including human dilated cardiomyopathy, pressure overload-induced heart failure, ischemic heart diseases, and aging-related cardiac metabolism disorder. The collected information would provide insights into the understanding of the HSP22 in heart diseases and lead to discovering the therapeutic targets.

IGF IIRα-triggered pathological manifestations in the heart aggravate renal inflammation in STZ-induced type-I diabetes rats

Pathological manifestations in either heart or kidney impact the function of the other and form the basis for the development of cardiorenal syndrome. However, the mechanism or factors involved in such scenario are not completely elucidated. In our study, to find the correlation between late fetal gene expression in diabetic hearts and their influence on diabetic nephropathy, we created a rat model with cardiac specific overexpression of IGF-IIRα, which is an alternative splicing variant of IGFIIR, expressed in pathological hearts. In this study, transgenic rats over expressing cardiac specific IGF-IIRα and non-transgenic animal models established in SD rats were administered with single dose of streptozotocin (STZ, 55 mg/Kg) to induce Type I diabetes. The correlation between IGF-IIRα and kidney damages were further determined based on their intensity of damage in the kidneys. The results show that cardiac specific overexpression of IGF-IIRα elevates the diabetes associated inflammation and morphological changes in the kidneys. The diabetic transgenic rats showed advancement in the pathological features such a renal tubular damage, collagen accumulation and enhancement in STAT3 associated mechanism of renal fibrosis. The results therefore show that that IGF-IIRα expression in the heart during pathological condition may worsen symptoms of diabetic nephropathy in rats.

Modulations of Cardiac Functions and Pathogenesis by Reactive Oxygen Species and Natural Antioxidants

Homeostasis in the level of reactive oxygen species (ROS) in cardiac myocytes plays a critical role in regulating their physiological functions. Disturbance of balance between generation and removal of ROS is a major cause of cardiac myocyte remodeling, dysfunction, and failure. Cardiac myocytes possess several ROS-producing pathways, such as mitochondrial electron transport chain, NADPH oxidases, and nitric oxide synthases, and have endogenous antioxidation mechanisms. Cardiac Ca2+-signaling toolkit proteins, as well as mitochondrial functions, are largely modulated by ROS under physiological and pathological conditions, thereby producing alterations in contraction, membrane conductivity, cell metabolism and cell growth and death. Mechanical stresses under hypertension, post-myocardial infarction, heart failure, and valve diseases are the main causes for stress-induced cardiac remodeling and functional failure, which are associated with ROS-induced pathogenesis. Experimental evidence demonstrates that many cardioprotective natural antioxidants, enriched in foods or herbs, exert beneficial effects on cardiac functions (Ca2+ signal, contractility and rhythm), myocytes remodeling, inflammation and death in pathological hearts. The review may provide knowledge and insight into the modulation of cardiac pathogenesis by ROS and natural antioxidants.

Pleiotropic activity of nerve growth factor in regulating cardiac functions and counteracting pathogenesis.

Cardiac innervation density generally reflects the levels of nerve growth factor (NGF) produced by the heart—changes in NGF expression within the heart and vasculature contribute to neuronal remodelling (e.g. sympathetic hyperinnervation or denervation). Its synthesis and release are altered under different pathological conditions. Although NGF is well known for its survival effects on neurons, it is clear that these effects are more wide ranging. Recent studies reported both in vitro and in vivo evidence for beneficial actions of NGF on cardiomyocytes in normal and pathological hearts, including prosurvival and antiapoptotic effects. NGF also plays an important role in the crosstalk between the nervous and cardiovascular systems. It was the first neurotrophin to be implicated in postnatal angiogenesis and vasculogenesis by autocrine and paracrine mechanisms. In connection with these unique cardiovascular properties of NGF, we have provided comprehensive insight into its function and potential effect of NGF underlying heart sustainable/failure conditions. This review aims to summarize the recent data on the effects of NGF on various cardiovascular neuronal and non‐neuronal functions. Understanding these mechanisms with respect to the diversity of NGF functions may be crucial for developing novel therapeutic strategies, including NGF action mechanism‐guided therapies.

Abstract 14620: LncExACT1 Acts as a Pivotal Switch Between Physiological and Pathological Cardiac Growth

Rationale: Pathological hypertrophy commonly leads to heart failure (HF) and loss of cardiomyocytes, while physiological hypertrophy protects the heart and enhances cardiomyogenesis. The mechanisms underlying these differences remain unclear. While long noncoding RNAs (lncRNAs) are important in cardiac development and disease, their role in physiological hypertrophy is unknown. Objective: To investigate the role of lncRNAs in physiological hypertrophy. Methods and Results: Mice underwent voluntary wheel running for eight weeks or transverse aortic constriction (TAC) for two or ten weeks. RNAseq identified a novel set of lncRNAs altered in exercised hearts, which we termed l ong n on c oding Ex ercise- A ssociated C ardiac T ranscripts (lncExACTs). lncExACT1 was highly conserved and uniquely downregulated in exercised hearts but upregulated in pathological animal models and hearts from HF patients vs controls (1.8-fold; p &lt;0.001, N=24) as well as plasma from HF patients with reduced (2.9-fold; p =0.032, N=16) and preserved ejection fraction (3.4-fold; p =0.006, N=18). In mice, AAV9 lncExACT1 overexpression increased cardiac lncExACT1 7-fold at 16 weeks and increased heart (HW) and lung (LW) weight relative to tibial length (TL), reduced fractional shortening (FS) and increased relative wall thickness (RWT) ( p &lt;0.05 for all). These changes were associated with a pathological gene expression pattern. In contrast, antisense lncExACT1 inhibition reduced cardiac expression 2-fold at 2 weeks and increased HW/TL without an increase in LW/TL, improved cardiac function, and increased RWT ( p &lt;0.05 for all). LncExACT1 inhibition induced a physiological gene expression pattern and increased markers of cardiomyogenesis. LncExACT1 inhibition reduced TAC-induced HW/TL and fibrosis, while increasing FS ( p &lt;0.05 for all). Mechanistic studies revealed that lncExACT1 works by binding miR-222 and as a novel regulator of Hippo/Yap1 signaling through modulation of dachsous cadherin-related 2. Conclusions: lncExACT1 acts as a master switch toggling the heart between physiological and pathological growth and provides a potentially tractable therapeutic target for harnessing the beneficial effects of exercise.

Review of Single-Cell RNA Sequencing in the Heart.

Single-cell RNA sequencing (scRNA-seq) technology is a powerful, rapidly developing tool for characterizing individual cells and elucidating biological mechanisms at the cellular level. Cardiovascular disease is one of the major causes of death worldwide and its precise pathology remains unclear. scRNA-seq has provided many novel insights into both healthy and pathological hearts. In this review, we summarize the various scRNA-seq platforms and describe the molecular mechanisms of cardiovascular development and disease revealed by scRNA-seq analysis. We then describe the latest technological advances in scRNA-seq. Finally, we discuss how to translate basic research into clinical medicine using scRNA-seq technology.

Measurement of J-Tpeakc along with QT-Interval Prolongation May Increase the Assay Sensitivity and Specificity for Predicting the Onset of Drug-Induced Torsade de Pointes: Experimental Evidences Based on Proarrhythmia Model Animals.

dl-Sotalol which can block both K+ channel and ß-adrenoceptor has been shown to prolong the J-Tpeakc of electrocardiogram in beagle dogs but tended to shorten it in microminipigs, although the drug prolonged the QT interval in both animals under physiologically maintained experimental condition. In order to estimate how the changes in the J-Tpeakc in the normal hearts would be reflected in the pathologic hearts, we compared proarrhythmic effects of dl-sotalol by using proarrhythmia models of beagle dogs and microminipigs, of which atrioventricular node had been ablated > 2months and 8-9weeks before, respectively (n = 4 for each species). dl-Sotalol in an oral dose of 10mg/kg induced torsade de pointes in three out of four beagle dogs, which degenerated into ventricular fibrillation. In microminipigs, the same dose did not trigger torsade de pointes at all, whereas intermittent ventricular pauses were observed in each animal after the drug treatment. These results indicate that assessment of the J-Tpeakc along with the QT-interval prolongation in healthy subjects may provide reliable information of risk prediction for patients susceptible to the drug-induced torsade de pointes.

Abstract 279: Effects of Acute Oxidative Stress on Cardiac Proteome Dynamics

Introduction: Acute reactive oxygen species exposure is thought to trigger endoplasmic reticulum (ER) stress and unfolded protein response (UPR) commonly observed in pathological hearts. The pathways and molecular features impacted by acute oxidative stress are incompletely understood. To understand how proteostatic stressors impact cardiac protein dynamics, we investigate the effect of low to high doses of acute oxidant on the cardiac proteome using a paraquat-induced oxidative stress model. Methods: C57BL/6J mice were exposed to low, mid, or high doses of paraquat for up to 48 hours. Cardiac proteins were extracted and digested on-filters into tryptic peptides. The peptides were then tagged with isobaric stable isotope tandem mass tags (TMT) followed by high-pH reversed-phase (RP) fractionation. Each fraction was further separated by low-pH RP liquid chromatography and analyzed on a Q-Exactive HF Plus high-resolution mass spectrometer to obtain proteome-wide abundance levels across treatment groups. We then focused on the differential expression in the mitochondrial and ER subproteomes as well as their respective protein quality control pathways. Results: We found prominent differential expression in specific quality control proteins in response across low and high doses of oxidative stresses. The data suggest that oxidative stress activates UPR pathways including notably mitochondrial UPR (UPRmt) components in a dose-specific manner. In particular, we observed the repression of mitochondrial protein import machinery components as a specific feature of low but not high oxidative stress response. In addition, the differential expression of pyruvate metabolism proteins may constitute a link between cardiac metabolism and UPRmt, and serve as a determinant between adaptive and maladaptive responses to reactive oxygen species. Conclusion: Our results indicate that the activation of the UPRmt pathways may be an overlooked feature of acute oxidative insults that underlies stress response in cardiac cells. Future work will interrogate the molecular crosstalks between mitochondria and ER stress response pathways.

Astragaloside IV protects against the pathological cardiac hypertrophy in mice

Although pathologic hypertrophic hearts currently maintain output, sustained cardiac hypertrophy could predispose a patient to arrhythmia and sudden death, and also cause heart failure. Thus, finding effective treatment and exploring the underlying molecular mechanisms of cardiac hypertrophy is urgently necessary. Astragaloside IV (AST-IV) is the main active component, extracted from the traditional Chinese medicinal herb Astragalus membranaceus. Previous studies have indicated that AST-IV has various bioactivities, such as anti-cancer, anti-oxidative stress and anti-inflammation. In the present study, we aimed to explore the effects of AST-IV on cardiac hypertrophy induced by aortic banding (AB) surgery in mice, and to reveal the underlying signaling mechanisms. The suppressor of IKKε (SIKE) is a negative regulator of the interferon pathway, which could be enhanced by AST-IV to ameliorate pathological cardiac hypertrophy in mice through inactivating TANK-binding kinase 1 (TBK1)/PI3K/AKT signaling pathway. AST-IV attenuated cardiac hypertrophy, collagen accumulation and abnormal cardiac functions. In addition, AB-induced apoptosis and inflammation in the heart tissue samples of mice, which were attenuated by AST-IV administration through inhibiting SIKE expression levels. Together, the findings above indicated that AST-IV might be a potential candidate to prevent cardiac hypertrophy via elevating SIKE to suppress TBK1/PI3K/AKT activity.

Ultrasound functional imaging in an ex vivo beating porcine heart platform

In recent years, novel ultrasound functional imaging (UFI) techniques have been introduced to assess cardiac function by measuring, e.g. cardiac output (CO) and/or myocardial strain. Verification and reproducibility assessment in a realistic setting remain major issues. Simulations and phantoms are often unrealistic, whereas in vivo measurements often lack crucial hemodynamic parameters or ground truth data, or suffer from the large physiological and clinical variation between patients when attempting clinical validation. Controlled validation in certain pathologies is cumbersome and often requires the use of lab animals.In this study, an isolated beating pig heart setup was adapted and used for performance assessment of UFI techniques such as volume assessment and ultrasound strain imaging. The potential of performing verification and reproducibility studies was demonstrated. For proof-of-principle, validation of UFI in pathological hearts was examined.Ex vivo porcine hearts (n = 6, slaughterhouse waste) were resuscitated and attached to a mock circulatory system. Radio frequency ultrasound data of the left ventricle were acquired in five short axis views and one long axis view. Based on these slices, the CO was measured, where verification was performed using flow sensor measurements in the aorta. Strain imaging was performed providing radial, circumferential and longitudinal strain to assess reproducibility and inter-subject variability under steady conditions. Finally, strains in healthy hearts were compared to a heart with an implanted left ventricular assist device, simulating a failing, supported heart.Good agreement between ultrasound and flow sensor based CO measurements was found. Strains were highly reproducible (intraclass correlation coefficients >0.8). Differences were found due to biological variation and condition of the hearts. Strain magnitude and patterns in the assisted heart were available for different pump action, revealing large changes compared to the normal condition. The setup provides a valuable benchmarking platform for UFI techniques. Future studies will include work on different pathologies and other means of measurement verification.

Hands-on surgical training of congenital heart surgery using 3-dimensional print models

ObjectivePatient-based congenital heart surgery (CHS) training is opportunity-based and difficult. Three-dimensional (3D) print models of the heart were used for hands-on surgical training (HOST) at the 2015 AATS and subsequently in 2 local institutions. We aim to introduce the process of 3D printing for surgical simulation and to present the attendee's responses. MethodsUsing CT or MR angiograms, the models of congenital heart disease were created and printed with flexible rubberlike material. Altogether, 81 established surgeons or trainees performed simulated surgical procedures with the expert surgeons' guidance and supervision. At the completion of the session, 50 of 81 attendees participated in the questionnaire assessment of the program. ResultsAll responders found the course helpful in improving their surgical skills. All would consider including HOST sessions in the training programs. All found that the models showed the necessary pathologic findings. Most found that the consistency and elasticity of the model material were different from those of the human myocardium. However, the responders thought that the quality of the models was acceptable (88%) or manageable (12%) for surgical practice. The major weaknesses listed were related to the print material and poor representation of the cardiac valves. ConclusionsHOST using 3D print heart models is achievable and allows surgical practice on pathological hearts without patients' risk. HOST is a highly applicable surgical simulation format for CHS. Incorporation of HOST in training programs could change the traditional opportunity-based education to the requirement-based standardized education.