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https://www.readbyqxmd.com/read/28639137/the-frank-starling-law-a-jigsaw-of-titin-proportions
#1
REVIEW
Vasco Sequeira, Jolanda van der Velden
The Frank-Starling Law dictates that the heart is able to match ejection to the dynamic changes occurring during cardiac filling, hence efficiently regulating isovolumetric contraction and shortening. In the last four decades, efforts have been made to identify a common fundamental basis for the Frank-Starling heart that can explain the direct relationship between muscle lengthening and its increased sensitization to Ca(2+). The term 'myofilament length-dependent activation' describes the length-dependent properties of the myofilaments, but what is(are) the underlying molecular mechanism(s) is a matter of ongoing debate...
June 21, 2017: Biophysical Reviews
https://www.readbyqxmd.com/read/28606867/testosterone-deficiency-prevents-left-ventricular-contractility-dysfunction-after-myocardial-infarction
#2
REVIEW
R F Ribeiro Júnior, K S Ronconi, I C G Jesus, P W M Almeida, L Forechi, D V Vassallo, S Guatimosim, I Stefanon, A A Fernandes
Testosterone may affect myocardial contractility since its deficiency decreases the contraction and relaxation of the heart. Meanwhile, testosterone replacement therapy has raised concerns because it may worsen cardiac dysfunction and remodeling after myocardial infarction (MI). In this study, we evaluate cardiac contractility 60 days after MI in rats with suppressed testosterone. Male Wistar rats underwent bilateral orchidectomy one week before the ligation of the anterior descending left coronary artery. The animals were divided into orchidectomized (OCT); MI; orchidectomized + MI (OCT + MI); orchidectomized + MI + testosterone (OCT + MI + T) and control (Sham) groups...
June 9, 2017: Molecular and Cellular Endocrinology
https://www.readbyqxmd.com/read/28596337/cardiac-regeneration-strategies-staying-young-at-heart
#3
REVIEW
Eldad Tzahor, Kenneth D Poss
The human heart is continually operating as a muscular pump, contracting, on average, 80 times per minute to propel 8000 liters of blood through body tissues each day. Whereas damaged skeletal muscle has a profound capacity to regenerate, heart muscle, at least in mammals, has poor regenerative potential. This deficiency is attributable to the lack of resident cardiac stem cells, combined with roadblocks that limit adult cardiomyocytes from entering the cell cycle and completing division. Insights for regeneration have recently emerged from studies of animals with an elevated innate capacity for regeneration, the innovation of stem cell and reprogramming technologies, and a clearer understanding of the cardiomyocyte genetic program and key extrinsic signals...
June 9, 2017: Science
https://www.readbyqxmd.com/read/28587976/mechanosensing-of-matrix-by-stem-cells-from-contractility-and-matrix-heterogeneity-to-cardiogenesis-and-muscle-stem-cells
#4
REVIEW
Lucas Smith, Sangkyun Cho, Dennis E Discher
Stem cells are particularly 'plastic' cell types that are induced by various cues to become specialized, tissue-functional lineages by switching on the expression of specific gene programs. Matrix stiffness is among the cues that multiple stem cell types can sense and respond to. This seminar-style review focuses on mechanosensing of matrix elasticity in the differentiation or early maturation of a few illustrative stem cell types, with an intended audience of biologists and physical scientists. Contractile forces applied by a cell's acto-myosin cytoskeleton are often resisted by the extracellular matrix and transduced through adhesions and the cytoskeleton ultimately into the nucleus to modulate gene expression...
June 3, 2017: Seminars in Cell & Developmental Biology
https://www.readbyqxmd.com/read/28578382/astragaloside-iv-alleviates-heart-failure-via-activating-ppar%C3%AE-to-switch-glycolysis-to-fatty-acid-%C3%AE-oxidation
#5
Zhiwei Dong, Pei Zhao, Ming Xu, Chen Zhang, Wei Guo, Huihua Chen, Jing Tian, Hongchang Wei, Rong Lu, Tongtong Cao
In heart failure (HF), energy metabolism pathway in cardiac muscle changes from fatty acid β-oxidation to glycolysis. However, the exact mechanism is unknown. Sarcoendoplasmic reticulum Ca(2+)α ATPase (SERCA) expression is downregulated and mitochondrial function is reduced in HF, perhaps partly due to a substantially reduced energy supply for excitation-contraction coupling resulting from a lower fatty acid β-oxidation rate. We investigated whether Astragaloside IV can activate peroxisome proliferator-activated receptor alpha (PPARα) to stimulate fatty acid β-oxidation and increase cardiac energy production, improving mitochondrial function and the efficiency of SERCA in HF...
June 2, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28577155/rbm20-a-potential-target-for-treatment-of-cardiomyopathy-via-titin-isoform-switching
#6
REVIEW
Wei Guo, Mingming Sun
Cardiomyopathy, also known as heart muscle disease, is an unfavorable condition leading to alterations in myocardial contraction and/or impaired ability of ventricular filling. The onset and development of cardiomyopathy have not currently been well defined. Titin is a giant multifunctional sarcomeric filament protein that provides passive stiffness to cardiomyocytes and has been implicated to play an important role in the origin and development of cardiomyopathy and heart failure. Titin-based passive stiffness can be mainly adjusted by isoform switching and post-translational modifications in the spring regions...
June 2, 2017: Biophysical Reviews
https://www.readbyqxmd.com/read/28571696/functional-electrical-stimulation-improves-muscle-strength-and-endurance-in-patients-after-cardiac-surgery-a-randomized-controlled-trial
#7
Jociane Schardong, Gabriela Castro Kuinchtner, Graciele Sbruzzi, Rodrigo Della Méa Plentz, Antônio Marcos Vargas da Silva
BACKGROUND: Functional electrical stimulation (FES) has shown benefits in patients with chronic heart failure. Therefore, it is possible that FES can benefit patients similarly after cardiac surgery. OBJECTIVE: This randomized placebo-controlled trial aimed to evaluate the effects of FES on lower limb functional capacity, strength, endurance, and muscle mass after discharge from cardiac surgery. METHODS: Twenty patients were allocated (1:1) to the group receiving FES to the quadriceps (FESG) or FES placebo (FESPG)...
May 19, 2017: Brazilian Journal of Physical Therapy
https://www.readbyqxmd.com/read/28571132/cardiovascular-response-and-serum-interleukin-6-level-in-concentric-vs-eccentric-exercise
#8
Mayank Agarwal, Shraddha Singh, Jagdish Narayan, Shivani Pandey, Sunita Tiwari, Priyanka Sharma
INTRODUCTION: Cardiovascular Disease (CVD) is a leading cause of morbidity and mortality in India. Resistance exercise is strongly recommended for implementation in CVD prevention programs. Dynamic resistance exercise comprises of concentric (muscle shortening) and eccentric (muscle lengthening) phase. The contraction of skeletal muscle promotes the synthesis and secretion of cytokines and peptides from myocytes, known as 'myokines'. Interleukin-6 (IL-6) is the first myokine to be released in the blood in response to exercise...
April 2017: Journal of Clinical and Diagnostic Research: JCDR
https://www.readbyqxmd.com/read/28557670/validity-and-reliability-of-the-moxy-oxygen-monitor-during-incremental-cycling-exercise
#9
E M Crum, W J O'Connor, L Van Loo, M Valckx, S R Stannard
INTRODUCTION: The Moxy is a novel, cutaneously placed muscle oxygen monitor which claims to measure local oxygen saturation (SmO2) and total haemoglobin (THb) using near-infrared spectroscopy. If shown to be reliable, its data storage and telemetric capability will be useful for assessing localised O2 usage during field-based exercise. This study investigated the reliability of the Moxy during cycling and assessed the correlations between its measurements, whole-body O2 consumption (VO2) and heart rate (HR)...
May 30, 2017: European Journal of Sport Science
https://www.readbyqxmd.com/read/28553667/translation-of-cardiac-myosin-activation-with-2-deoxy-atp-to-treat-heart-failure-via-an-experimental-ribonucleotide-reductase-based-gene-therapy
#10
Kassandra S Thomson, Guy L Odom, Charles E Murry, Gregory G Mahairas, Farid Moussavi-Harami, Sam L Teichman, Xiaolan Chen, Stephen D Hauschka, Jeffrey S Chamberlain, Michael Regnier
Despite recent advances, chronic heart failure remains a significant and growing unmet medical need, reaching epidemic proportions carrying substantial morbidity, mortality, and costs. A safe and convenient therapeutic agent that produces sustained inotropic effects could ameliorate symptoms, and improve functional capacity and quality of life. We discovered small amounts of 2-deoxy-ATP (dATP) activate cardiac myosin leading to enhanced contractility in normal and failing heart muscle. Cardiac myosin activation triggers faster myosin crossbridge cycling with greater force generation during each contraction...
December 2016: JACC. Basic to Translational Science
https://www.readbyqxmd.com/read/28552745/a-critical-role-for-cystathionine-%C3%AE-synthase-in-hydrogen-sulfide-mediated-hypoxic-relaxation-of-the-coronary-artery
#11
J Donovan, P S Wong, R Roberts, M J Garle, S P H Alexander, W R Dunn, V Ralevic
Hypoxia-induced coronary artery vasodilatation protects the heart by increasing blood flow under ischemic conditions, however its mechanism is not fully elucidated. Hydrogen sulfide (H2S) is reported to be an oxygen sensor/transducer in the vasculature. The present study aimed to identify and characterise the role of H2S in the hypoxic response of the coronary artery, and to define the H2S synthetic enzymes involved. Immunoblotting and immunohistochemistry showed expression of all three H2S-producing enzymes, cystathionine-β-synthase (CBS), cystathionine-γ-lyase (CSE) and 3-mercaptopyruvate sulfurtransferase (MPST), in porcine coronary artery...
May 25, 2017: Vascular Pharmacology
https://www.readbyqxmd.com/read/28543276/to-the-heart-of-activation-heat
#12
Hamish M Aitken-Buck, Regis R Lamberts
Cardiac muscle functions as a molecular machine that converts an electrical stimulus into a Ca(2+) -dependent mechanical contraction. This article is protected by copyright. All rights reserved.
May 24, 2017: Journal of Physiology
https://www.readbyqxmd.com/read/28531217/store-operated-ca2-entry-supports-contractile-function-in-hearts-of-hibernators
#13
Olga V Nakipova, Alexey S Averin, Edward V Evdokimovskii, Oleg Yu Pimenov, Leonid Kosarski, Dmitriy Ignat'ev, Andrey Anufriev, Yuri M Kokoz, Santiago Reyes, Andre Terzic, Alexey E Alekseev
Hibernators have a distinctive ability to adapt to seasonal changes of body temperature in a range between 37°C and near freezing, exhibiting, among other features, a unique reversibility of cardiac contractility. The adaptation of myocardial contractility in hibernation state relies on alterations of excitation contraction coupling, which becomes less-dependent from extracellular Ca2+ entry and is predominantly controlled by Ca2+ release from sarcoplasmic reticulum, replenished by the Ca2+-ATPase (SERCA)...
2017: PloS One
https://www.readbyqxmd.com/read/28516252/chronic-eccentric-arm-cycling-improves-maximum-upper-body-strength-and-power
#14
Steven J Elmer, Dakota J Anderson, Travis R Wakeham, Matthew A Kilgas, John J Durocher, Stan L Lindstedt, Paul C LaStayo
INTRODUCTION: Eccentric leg cycling (cycle ergometry adapted to impose muscle lengthening contractions) offers an effective exercise for restoring lower-body muscular function, maintaining health, and improving performance in clinical and athletic populations. PURPOSE: We extended this model to the upper body and evaluated the effectiveness of a 7-week eccentric arm cycling (ECCarm) intervention to improve upper-body muscular function. We also explored whether ECCarm would alter arterial function...
May 17, 2017: European Journal of Applied Physiology
https://www.readbyqxmd.com/read/28510118/tampering-with-springs-phosphorylation-of-titin-affecting-the-mechanical-function-of-cardiomyocytes
#15
REVIEW
Nazha Hamdani, Melissa Herwig, Wolfgang A Linke
Reversible post-translational modifications of various cardiac proteins regulate the mechanical properties of the cardiomyocytes and thus modulate the contractile performance of the heart. The giant protein titin forms a continuous filament network in the sarcomeres of striated muscle cells, where it determines passive tension development and modulates active contraction. These mechanical properties of titin are altered through post-translational modifications, particularly phosphorylation. Titin contains hundreds of potential phosphorylation sites, the functional relevance of which is only beginning to emerge...
April 10, 2017: Biophysical Reviews
https://www.readbyqxmd.com/read/28508197/antinociceptive-effect-of-the-agonist-of-5-ht1a-receptors-buspirone-in-the-model-of-abdominal-pain-in-dogs
#16
O A Lyubashina, I I Busygina, S S Panteleev, A D Nozdrachev
We have demonstrated that activation of 5-HT1A receptors with buspirone promotes visceral analgesia in awake dogs. The administration of 0.035 mg/kg (i.m.) of the drug caused depression of viscero-motor (contraction of the abdominal muscles) and pressor (increase in the heart rate) responses to noxious distension of the large intestine. An increase in the dose to 0.07 and 0.14 mg/kg did not enhance the antinociceptive effect of buspirone but triggered basal tachycardia. The obtained results provide evidence of the inhibitory role of 5-HT1A receptors in modulating visceral pain sensitivity and the possibility of an exciting effect of their activation on the cardiovascular system...
March 2017: Doklady Biological Sciences: Proceedings of the Academy of Sciences of the USSR, Biological Sciences Sections
https://www.readbyqxmd.com/read/28481238/the-adenosinergic-system-as-a-therapeutic-target-in-the-vasculature-new-ligands-and-challenges
#17
REVIEW
Joana Beatriz Sousa, Carmen Diniz
Adenosine is an adenine base purine with actions as a modulator of neurotransmission, smooth muscle contraction, and immune response in several systems of the human body, including the cardiovascular system. In the vasculature, four P1-receptors or adenosine receptors-A₁, A2A, A2B and A₃-have been identified. Adenosine receptors are membrane G-protein receptors that trigger their actions through several signaling pathways and present differential affinity requirements. Adenosine is an endogenous ligand whose extracellular levels can reach concentrations high enough to activate the adenosine receptors...
May 6, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/28474868/effects-of-drop-set-resistance-training-on-acute-stress-indicators-and-long-term-muscle-hypertrophy-and-strength
#18
Julius Fink, Brad J Schoenfeld, Naoki Kikuchi, Koichi Nakazato
BACKGROUND: We investigated the effects of 2 different resistance training (RT) protocols on muscle hypertrophy and strength. The first group (n = 8) performed a single drop set (DS) and the second group (n = 8) performed 3 sets of conventional RT (normal set, NS). METHODS: Eight young men in each group completed 6 weeks of RT. Muscle hypertrophy was assessed via magnetic resonance imaging (MRI) and strength via 12 RM tests before and after the 6 weeks. Acute stress markers such as muscle thickness (MT), blood lactate (BL), maximal voluntary contraction (MVC), heart rate (HR) and rating of perceived exertion (RPE) before and after one bout of RT...
April 26, 2017: Journal of Sports Medicine and Physical Fitness
https://www.readbyqxmd.com/read/28459744/electrical-stimulation-of-artificial-heart-muscle-a-look-into-the-electrophysiologic-and-genetic-implications
#19
Mohamed A Mohamed, Jose F Islas, Robert J Schwartz, Ravi K Birla
Development of tissue-engineered hearts for treatment of myocardial infarction or biologic pacemakers has been hindered by the production of mostly arrhythmic or in-synergistic constructs. Electrical stimulation (ES) of these constructs has been shown to produce tissues with greater twitch force and better adrenergic response. To further our understanding of the mechanisms underlying the effect of ES, we fabricated a bioreactor capable of delivering continuous or intermittent waveforms of various types to multiple constructs simultaneously...
May 2017: ASAIO Journal: a Peer-reviewed Journal of the American Society for Artificial Internal Organs
https://www.readbyqxmd.com/read/28457965/calcium-dynamics-in-cardiac-excitatory-and-non-excitatory-cells-and-the-role-of-gap-junction
#20
Phonindra Nath Das, Parul Mehrotra, Aseem Mishra, Nandadulal Bairagi, Samrat Chatterjee
Calcium ions aid in the generation of action potential in myocytes and are responsible for the excitation-contraction coupling of heart. The heart muscle has specialized patches of cells, called excitatory cells (EC) such as the Sino-atrial node cells capable of auto-generation of action potential and cells which receive signals from the excitatory cells, called non-excitatory cells (NEC) such as cells of the ventricular and auricular walls. In order to understand cardiac calcium homeostasis, it is, therefore, important to study the calcium dynamics taking into account both types of cardiac cells...
April 27, 2017: Mathematical Biosciences
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