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https://www.readbyqxmd.com/read/28721030/regular-physical-exercise-improves-cardiac-autonomic-and-muscle-vasodilatory-responses-to-isometric-exercise-in-healthy-elderly
#1
Adriana de Oliveira Sarmento, Amilton da Cruz Santos, Ivani Credidio Trombetta, Marciano Moacir Dantas, Ana Cristina Oliveira Marques, Leone Severino do Nascimento, Bruno Teixeira Barbosa, Marcelo Rodrigues Dos Santos, Maria do Amparo Andrade, Anna Myrna Jaguaribe-Lima, Maria do Socorro Brasileiro-Santos
The objective of this study was to evaluate cardiac autonomic control and muscle vasodilation response during isometric exercise in sedentary and physically active older adults. Twenty healthy participants, 10 sedentary and 10 physically active older adults, were evaluated and paired by gender, age, and body mass index. Sympathetic and parasympathetic cardiac activity (spectral and symbolic heart rate analysis) and muscle blood flow (venous occlusion plethysmography) were measured for 10 minutes at rest (baseline) and during 3 minutes of isometric handgrip exercise at 30% of the maximum voluntary contraction (sympathetic excitatory maneuver)...
2017: Clinical Interventions in Aging
https://www.readbyqxmd.com/read/28720715/ischemic-preconditioning-does-not-alter-muscle-sympathetic-responses-to-static-handgrip-and-metaboreflex-activation-in-young-healthy-men
#2
Anthony V Incognito, Connor J Doherty, Jordan B Lee, Matthew J Burns, Philip J Millar
Ischemic preconditioning (IPC) has been hypothesized to elicit ergogenic effects by reducing feedback from metabolically sensitive group III/IV muscle afferents during exercise. If so, reflex efferent neural outflow should be attenuated. We investigated the effects of IPC on muscle sympathetic nerve activity (MSNA) during static handgrip (SHG) and used post-exercise circulatory occlusion (PECO) to isolate for the muscle metaboreflex. Thirty-seven healthy men (age: 24 ± 5 years [mean ± SD]) were randomized to receive sham (n = 16) or IPC (n = 21) interventions...
July 2017: Physiological Reports
https://www.readbyqxmd.com/read/28717924/hypertrophic-cardiomyopathy-and-the-myosin-mesa-viewing-an-old-disease-in-a-new-light
#3
REVIEW
Darshan V Trivedi, Arjun S Adhikari, Saswata S Sarkar, Kathleen M Ruppel, James A Spudich
The sarcomere is an exquisitely designed apparatus that is capable of generating force, which in the case of the heart results in the pumping of blood throughout the body. At the molecular level, an ATP-dependent interaction of myosin with actin drives the contraction and force generation of the sarcomere. Over the past six decades, work on muscle has yielded tremendous insights into the workings of the sarcomeric system. We now stand on the cusp where the acquired knowledge of how the sarcomere contracts and how that contraction is regulated can be extended to an understanding of the molecular mechanisms of sarcomeric diseases, such as hypertrophic cardiomyopathy (HCM)...
July 17, 2017: Biophysical Reviews
https://www.readbyqxmd.com/read/28717163/titin-mediated-thick-filament-activation-through-a-mechanosensing-mechanism-introduces-sarcomere-length-dependencies-in-mathematical-models-of-rat-trabecula-and-whole-ventricle
#4
Lorenzo Marcucci, Takumi Washio, Toshio Yanagida
Recent experimental evidence in skeletal muscle demonstrated the existence of a thick-filament mechanosensing mechanism, acting as a second regulatory system for muscle contraction, in addition to calcium-mediated thin filament regulation. These two systems cooperate to generate force, but the extent to which their interaction is relevant in physiologically contracting muscle was not yet assessed experimentally. Therefore, we included both regulatory mechanisms in a mathematical model of rat trabecula and whole ventricle...
July 17, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28706255/mitsugumin-29-regulates-t-tubule-architecture-in-the-failing-heart
#5
Robert N Correll, Jeffrey M Lynch, Tobias G Schips, Vikram Prasad, Allen J York, Michelle A Sargent, Didier X P Brochet, Jianjie Ma, Jeffery D Molkentin
Transverse tubules (t-tubules) are uniquely-adapted membrane invaginations in cardiac myocytes that facilitate the synchronous release of Ca(2+) from internal stores and subsequent myofilament contraction, although these structures become disorganized and rarefied in heart failure. We previously observed that mitsugumin 29 (Mg29), an important t-tubule organizing protein in skeletal muscle, was induced in the mouse heart for the first time during dilated cardiomyopathy with heart failure. Here we generated cardiac-specific transgenic mice expressing Mg29 to model this observed induction in the failing heart...
July 13, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28699532/modulation-of-heart-rate-by-acute-or-chronic-aerobic-exercise-potential-effects-on-blood-pressure-control
#6
Carme Perez-Quilis, J Derek Kingsley, Kabir Malkani, Gianfranco Cervellin, Giuseppe Lippi, Fabian Sanchis-Gomar
It was initially assumed that heart rate and arterial blood pressure were modulated by normal respiration and muscle contraction. The arterial baroreflex, an inverse relationship between blood pressure and heart rate, was later reported. Nonetheless, it was then assumed that those responses involved vagal modulation. We summarize available evidence on the modulation of heart rate by acute or chronic aerobic exercise as well as its potential implications on BP control. Numerous studies have tried to clarify whether aerobic exercise modifies neurally-mediated vasoconstriction, but they report contradictory results...
July 10, 2017: Current Pharmaceutical Design
https://www.readbyqxmd.com/read/28698364/loss-of-mouse-cardiomyocyte-talin-1-and-talin-2-leads-to-%C3%AE-1-integrin-reduction-costameric-instability-and-dilated-cardiomyopathy
#7
Ana Maria Manso, Hideshi Okada, Francesca M Sakamoto, Emily Moreno, Susan J Monkley, Ruixia Li, David R Critchley, Robert S Ross
Continuous contraction-relaxation cycles of the heart require strong and stable connections of cardiac myocytes (CMs) with the extracellular matrix (ECM) to preserve sarcolemmal integrity. CM attachment to the ECM is mediated by integrin complexes localized at the muscle adhesion sites termed costameres. The ubiquitously expressed cytoskeletal protein talin (Tln) is a component of muscle costameres that links integrins ultimately to the sarcomere. There are two talin genes, Tln1 and Tln2. Here, we tested the function of these two Tln forms in myocardium where Tln2 is the dominant isoform in postnatal CMs...
July 11, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28694237/phase-transitions-during-compression-and-decompression-of-clots-from-platelet-poor-plasma-platelet-rich-plasma-and-whole-blood
#8
Xiaojun Liang, Irina Chernysh, Prashant K Purohit
Blood clots are required to stem bleeding and are subject to a variety of stresses, but they can also block blood vessels and cause heart attacks and ischemic strokes. We measured the compressive response of human platelet-poor plasma (PPP) clots, platelet-rich plasma (PRP) clots and whole blood clots and correlated these measurements with confocal and scanning electron microscopy to track changes in clot structure. Stress-strain curves revealed four characteristic regions, for compression-decompression: 1) linear elastic region; 2) upper plateau or softening region; 3) non-linear elastic region or re-stretching of the network; 4) lower plateau in which dissociation of some newly made connections occurs...
July 7, 2017: Acta Biomaterialia
https://www.readbyqxmd.com/read/28677887/inferior-lead-discordance-in-ventricular-arrhythmias-a-specific-marker-for-certain-arrhythmia-locations
#9
Andres Enriquez, Rajeev K Pathak, Pasquale Santangeli, Jackson Jeikai Liang, Mohammed Al Rawahi, Tatsuya Hayashi, Danielle Muser, David S Frankel, Gregory Supple, Robert Schaller, David Lin, Saman Nazarian, Erica Zado, Francis E Marchlinski, Fermin C Garcia
BACKGROUND: Most idiopathic ventricular arrhythmias (VAs) originate from the outflow tracts and are characterized by an inferior axis on the 12-lead ECG. A group of patients will exhibit inferior lead discordance (ILD), demonstrating a positive QRS in lead II with negative QRS in III or the opposite finding. METHODS AND RESULTS: We identified patients undergoing ablation of idiopathic premature ventricular contractions (PVCs) or ventricular tachycardia (VT) between 2013 and 2015...
July 5, 2017: Journal of Cardiovascular Electrophysiology
https://www.readbyqxmd.com/read/28673260/gene-expression-variations-in-high-altitude-adaptation-a-case-study-of-the-asiatic-toad-bufo-gargarizans
#10
Weizhao Yang, Yin Qi, Bin Lu, Liang Qiao, Yayong Wu, Jinzhong Fu
BACKGROUND: Genome-wide investigation of molecular mechanisms for high-altitude adaptation has attracted great attention in the last few years. In order to understand the contribution of gene expression level variations to high-altitude adaptation in Asiatic toads (Bufo gargarizans), we implemented a reciprocal transplant experiment between low- and high-altitude sites and sequenced 12 transcriptomes from brain, heart, and liver tissues. RESULTS: A large number of genes with expression differences (DEGs) between high- and low-altitude individuals (193 fixed and 844 plastic) were identified, and the majority of them were tissue specific...
July 3, 2017: BMC Genetics
https://www.readbyqxmd.com/read/28671972/diaphragm-a-mnemonic-to-describe-the-work-of-breathing-in-patients-with-respiratory-failure
#11
Aiman Tulaimat, William E Trick
BACKGROUND: The assessment of the work of breathing in the definitions of respiratory failure is vague and variable. OBJECTIVE: Identify a parsimonious set of signs to describe the work of breathing in hypoxemic, acutely ill patients. METHODS: We examined consecutive medical ICU patients receiving oxygen with a mask, non-invasive ventilation, or T-piece. A physician inspected each patient for 10 seconds, rated the level of respiratory distress, and then examined the patient for vital signs and 17 other physical signs...
2017: PloS One
https://www.readbyqxmd.com/read/28639137/the-frank-starling-law-a-jigsaw-of-titin-proportions
#12
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
#13
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
#14
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
#15
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
#16
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
#17
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
#18
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)...
July 2017: Brazilian Journal of Physical Therapy
https://www.readbyqxmd.com/read/28571132/cardiovascular-response-and-serum-interleukin-6-level-in-concentric-vs-eccentric-exercise
#19
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
#20
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
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