J002 The cAMP binding protein Epac regulates cardiac myofilament function

In the heart, cAMP is a key regulator of excitation—contraction coupling and its biological effects are mainly associated with the activity of protein kinase A (PKA). The aim of this study was to investigate the contribution of the cAMP-binding protein Epac (Exchange protein directly activated by cAMP) in the regulation of the contractile properties of rat ventricular cardiac myocytes. We report that both PKA and Epac increased cardiac sarcomere contraction but through opposite mechanisms. Differently from PKA, selective Epac activation by the cAMP analog 8-pCPT reduced Ca2+ transient amplitude and increased cell shortening in intact cardiomyocytes as well as myofilament Ca2+ sensitivity in permeabilized cardiomyocytes. Moreover, ventricular myocytes, which were infected in vivo with a constitutively active form of Epac, showed enhanced myofilament Ca2+ sensitivity compared to control cells infected with GFP alone. At the molecular level, Epac increased phosphorylation of two key sarcomeric proteins, cardiac Troponin I (cTnI) and cardiac Myosin Binding Protein-C (cMyBP-C). The effects of Epac activation on myofilament Ca2+ sensitivity and on cTnI and cMyBP-C phosphorylation were independent of PKA, and were blocked by protein kinase C (PKC) and Ca2+ calmodulin kinase II (CaMKII) inhibitors. Altogether these findings identify Epac as a new regulator of myofilament function

C009 Perte du gradient transmural de la fonction mitochondriale et altération du couplage excitation-contraction dans l’insuffisance cardiaque ischémique

L’insuffisance cardiaque (IC) est caractérisée par des altérations du métabolisme énergétique associées à une augmentation de la production de radicaux libres (RL). Les RL altèrent le couplage excitation-contraction (CEC) des myocytes en interagissant avec la signalisation calcique et les protéines contractiles. Chez des rats ayant subit une ligature de l’artère coronaire gauche (PMI), nous avons déterminé si, au stade d’insuffisance cardiaque, la perte du gradient transmural de contractilité et l’altération de la signalisation Ca2+ étaient associées à une dysfonction mitochondriale régionalisée au sein de la paroi du ventricule gauche (VG).Les propriétés métaboliques ont été évaluées en mesurant l’autofluorescence du NADH (microscopie multiphotonique), et les activités de la citrate synthase (CS) et de la cytochrome-c oxydase (COX) de cardiomyocytes isolés du sous-endocarde (ENDO) et du sousépicarde (EPI) du VG de rats PMI ou contrôles (sham). Parallèlement, nous avons mesuré les activités de la superoxyde dismutase (SOD) et de la catalase ainsi que la production mitochondriale de RL (MitoSOX) en microscopie confocale. Le raccourcissement cellulaire, la sensibilité au Ca2+ des myofilaments, le transitoire Ca2+, ainsi que les sparks Ca2+ ont été mesurés en absence ou en présence d’un antioxydant (N-acetyl cysteine NAC: 20mM).Chez les shams, l’utilisation du NADH au cours d’une stimulation électrique est plus importante dans l’ENDO que dans l’EPI et s’accompagne d’activités CS et COX plus élevées. Ce gradient transmural de capacité oxydative disparait au cours de l’IC en raison d’altérations localisées uniquement dans l’ENDO. Ces perturbations métaboliques sont associées à une diminution des défenses antioxydantes et à une élévation de la production de RL dans l’ENDO. Le NAC améliore les propriétés contractiles, la fuite diastolique de Ca2+ du réticulum sarcoplasmique (baisse de la fréquence des sparks spontanés) et réduit le nombre de transitoires Ca2+ ectopiques pro-arythmogéniques dans l’ENDO.En conclusion, la perte du gradient transmural de contractilité au cours de l’IC est partiellement due à une altération régionalisée de la fonction mitochondriale. De plus, la production exacerbée de RL associée aux troubles métaboliques participe à la genèse d’événements arythmiques dans la région sous-endocardique

Methods and pharmaceutical compositions for the cardioprotection

The present invention relates to methods and pharmaceutical compositions for cardioprotection of subjects who experienced a myocardial infarction. In particular, the present invention relates to a ligand of the sonic hedgehog signaling pathway for use in the cardioprotection of a subject who experienced a myocardial infarction

Founders, Feminists, and a Fascist -- Some Notable Women in the Missouri Section of the MAA

In the history of the Missouri Section of the MAA, some of the more interesting people who influenced the growth and development of the section through the years were and are women. In this chapter, we discuss the contributions of a few (certainly not all) of these women to the Missouri Section and mathematics as a whole, including Emily Kathryn Wyant (founder of KME), Margaret F. Willerding (who dealt with sexism in the 1940s), Maria Castellani (an official in Mussolini’s Italy before coming to America), and T. Christine Stevens (co-founder of Project NExT). Without them, and others like them, both mathematics and the Missouri Section of the MAA would be poorer

Nonenzymatic lipid mediators, neuroprostanes, exert the antiarrhythmic properties of docosahexaenoic acid

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Osteocalcin signaling in myofibers is necessary and sufficient for optimum adaptation to exercise

Circulating levels of undercarboxylated and bioactive osteocalcin double during aerobic exercise at the time levels of insulin decrease. In contrast, circulating levels of osteocalcin plummet early during adulthood in mice, monkeys, and humans of both genders. Exploring these observations revealed that osteocalcin signaling in myofibers is necessary for adaptation to exercise by favoring uptake and catabolism of glucose and fatty acids, the main nutrients of myofibers. Osteocalcin signaling in myofibers also accounts for most of the exercise-induced release of interleukin-6, a myokine that promotes adaptation to exercise in part by driving the generation of bioactive osteocalcin. We further show that exogenous osteocalcin is sufficient to enhance the exercise capacity of young mice and to restore to 15-month-old mice the exercise capacity of 3-month-old mice. This study uncovers a bone-to-muscle feedforward endocrine axis that favors adaptation to exercise and can reverse the age-induced decline in exercise capacity

Role of oxygen exposure on the differentiation of human induced pluripotent stem cells in 2D and 3D cardiac organoids

Introduction Human induced pluripotent stem cells (hiPSC) have the ability to differentiate theoritically into any cell type. The development of organoid systems exhibiting the essential features of human organ such as liver and heart is of high interest. Optimizing the culture conditions to obtain the highest cardiac organoids efficacy is crucial. In fact, cardiac differentiation protocols have been established by essentially focusing on specific growth factors on hiPSC differentiation efficiency. However, the optimal environmental factors such as the optimal oxygen exposure to obtain cardiac myocytes in network are still unclear. The mesoderm germ layer differentiation is known to be enhanced by low oxygen exposure. Yet, the effect of low oxygen exposure on the molecular and functional maturity of the hiPSC-derived cardiomyocytes remains unexplored. Aims We aimed here at comparing the molecular and functional consequences of low (5% O2 or LOE) and high oxygen exposure (21% O2 or HOE) on cardiac differentiation of hiPSCs in 2D monolayer and 3D organoids protocols. Methods hiPSC-CMs were differentiated through both the 2D (monolayer) and 3D (embryoid body) protocols using several lines. Cardiac marker expression and cell morphology were assessed using qRT-PCR and immunofluorescence. The mitochondrial localization and metabolic properties were evaluated by high-resolution respirometry and mitochondrial staining. The intracellular Ca2+ handling and contractile properties were also monitored using confocal fluorescent microscopy and atomic force microscopy. Results Our results indicated that the 2D cardiac monolayer can only be differentiated in HOE. The 3D cardiac organoids containing hiPSC-CMs in LOE exhibited higher cardiac markers expression such as troponin T (TnTc), RyR2, Serca2a, alpha and beta heavy myosin chains. Moreover, we found enhanced contractile force, hypertrophy and steadier SR Ca2+ release reflected by a more regular spontaneous Ca2+ transients associated with a higher maximal amplitude and lower spontaneous Ca2+ events revealing a better SR Ca2+ handling in LOE. Similar beat rate, preserved distribution of mitochondria and similar oxygen consumption by the mitochondrial respiratory chain complexes were also observed. Conclusions Our results brought evidences that LOE is moderately beneficial for the 3D cardiac organoids with hPSC-CMs exhibiting further maturity. In contrast, the 2D cardiac monolayers strictly require HOE.Introduction Human induced pluripotent stem cells (hiPSC) have the ability to differentiate theoritically into any cell type. The development of organoid systems exhibiting the essential features of human organ such as liver and heart is of high interest. Optimizing the culture conditions to obtain the highest cardiac organoids efficacy is crucial. In fact, cardiac differentiation protocols have been established by essentially focusing on specific growth factors on hiPSC differentiation efficiency. However, the optimal environmental factors such as the optimal oxygen exposure to obtain cardiac myocytes in network are still unclear. The mesoderm germ layer differentiation is known to be enhanced by low oxygen exposure. Yet, the effect of low oxygen exposure on the molecular and functional maturity of the hiPSC-derived cardiomyocytes remains unexplored. Aims We aimed here at comparing the molecular and functional consequences of low (5% O2 or LOE) and high oxygen exposure (21% O2 or HOE) on cardiac differentiation of hiPSCs in 2D monolayer and 3D organoids protocols. Methods hiPSC-CMs were differentiated through both the 2D (monolayer) and 3D (embryoid body) protocols using several lines. Cardiac marker expression and cell morphology were assessed using qRT-PCR and immunofluorescence. The mitochondrial localization and metabolic properties were evaluated by high-resolution respirometry and mitochondrial staining. The intracellular Ca2+ handling and contractile properties were also monitored using confocal fluorescent microscopy and atomic force microscopy. Results Our results indicated that the 2D cardiac monolayer can only be differentiated in HOE. The 3D cardiac organoids containing hiPSC-CMs in LOE exhibited higher cardiac markers expression such as troponin T (TnTc), RyR2, Serca2a, alpha and beta heavy myosin chains. Moreover, we found enhanced contractile force, hypertrophy and steadier SR Ca2+ release reflected by a more regular spontaneous Ca2+ transients associated with a higher maximal amplitude and lower spontaneous Ca2+ events revealing a better SR Ca2+ handling in LOE. Similar beat rate, preserved distribution of mitochondria and similar oxygen consumption by the mitochondrial respiratory chain complexes were also observed. Conclusions Our results brought evidences that LOE is moderately beneficial for the 3D cardiac organoids with hPSC-CMs exhibiting further maturity. In contrast, the 2D cardiac monolayers strictly require HOE

Energy autonomous wearable sensors for smart healthcare: a review

Energy Autonomous Wearable Sensors (EAWS) have attracted a large interest due to their potential to provide reliable measurements and continuous bioelectric signals, which help to reduce health risk factors early on, ongoing assessment for disease prevention, and maintaining optimum, lifelong health quality. This review paper presents recent developments and state-of-the-art research related to three critical elements that enable an EAWS. The first element is wearable sensors, which monitor human body physiological signals and activities. Emphasis is given on explaining different types of transduction mechanisms presented, and emerging materials and fabrication techniques. The second element is the flexible and wearable energy storage device to drive low-power electronics and the software needed for automatic detection of unstable physiological parameters. The third is the flexible and stretchable energy harvesting module to recharge batteries for continuous operation of wearable sensors. We conclude by discussing some of the technical challenges in realizing energy-autonomous wearable sensing technologies and possible solutions for overcoming them