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Wen Pan, Ziqi Yang, Jun Cheng, Cheng Qian, Yanggan Wang
The transmural heterogeneity of the contractility in ventricular muscle has not been well-studied. Here, we investigated the calcium transient and sarcomere contraction/relaxation in the endocardial (Endo) and epicardial (Epi) myocytes. Endo and Epi myocytes were isolated from C57/BL6 mice by Langendorff perfusion. Ca2+ transient and sarcomere contraction/relaxation were recorded simultaneously at different stimulation frequencies using a dual excitation fluorescence photomultiplier system. We found that the Endo myocytes have higher baseline diastolic calcium, significantly larger calcium transient and stronger sarcomere shortening than Epi myocytes...
August 2018: Journal of Cellular Physiology
Débora Wanderley, Andrea Lemos, Eduarda Moretti, Manuella Moraes Monteiro Barbosa Barros, Marcelo Moraes Valença, Daniella Araújo de Oliveira
The objective of this study was to evaluate the efficacy of proprioceptive neuromuscular facilitation (PNF) on range of motion (ROM) gain in young healthy adults. We performed a systematic review of randomized controlled trials and quasi-randomized trials, including young healthy adults. The interventions were: PNF compared with different PNF techniques, control, other muscle stretching exercises and musculoskeletal manipulations. The outcome measures were: articular ROM and adverse effects. The final number of included studies was 46, involving 1,864 adults...
February 23, 2018: Physiotherapy Theory and Practice
Cole Zmurchok, Dhananjay Bhaskar, Leah Edelstein-Keshet
Regulators of the actin cytoskeleton such Rho GTPases can modulate forces developed in cells by promoting actomyosin contraction. At the same time, through mechanosensing, tension is known to affect the activity of Rho GTPases. What happens when these effects act in concert? Using a minimal model (1 GTPase coupled to a Kelvin-Voigt element), we show that two-way feedback between signaling ('RhoA') and mechanical tension (stretching) leads to a spectrum of cell behaviors, including contracted or relaxed cells, and cells that oscillate between these extremes...
April 30, 2018: Physical Biology
Betzabé Nieto-Lima, Agustina Cano-Martínez, María E Rubio-Ruiz, Israel Pérez-Torres, Verónica Guarner-Lans
Different human-like cardiomyopathies associated to β-adrenergic stimulation are experimentally modeled in animals through variations in dose, route, and duration of administration of different cardiotoxic drugs. However, associated changes in the vasculature and their relation to systemic inflammation, and the influence of cardiovascular diseases risk factors (gender and age) upon them are seldom analyzed. Here we studied the effect of age and gender on the vasoreactivity of aortas from mice subjected to in vivo repeated β-adrenergic stimulation with different doses of isoproterenol (ISO) in association with circulating inflammatory cytokines...
2018: Frontiers in Physiology
Edward W Li, Olivia C McKee-Muir, Penney M Gilbert
Satellite cells, adult stem cells in skeletal muscle tissue, reside within a mechanically dynamic three-dimensional microenvironment. With each contraction-relaxation cycle, a satellite cell is expected to experience tensile, shear, and compressive stresses, and through cell-extracellular matrix interactions, also gauge the stiffness of the niche. Via mechanoreceptors, cells can sense these biophysical parameters of the niche, which serve to physically induce conformational changes that impact biomolecule activity, and thereby alter downstream signal transduction pathways and ultimately cell fate...
2018: Current Topics in Developmental Biology
Christopher J Payne, Isaac Wamala, Colette Abah, Thomas Thalhofer, Mossab Saeed, Daniel Bautista-Salinas, Markus A Horvath, Nikolay V Vasilyev, Ellen T Roche, Frank A Pigula, Conor J Walsh
Soft robotic devices have significant potential for medical device applications that warrant safe synergistic interaction with humans. This article describes the optimization of an implantable soft robotic system for heart failure whereby soft actuators wrapped around the ventricles are programmed to contract and relax in synchrony with the beating heart. Elastic elements integrated into the soft actuators provide recoiling function so as to aid refilling during the diastolic phase of the cardiac cycle. Improved synchronization with the biological system is achieved by incorporating the native ventricular pressure into the control system to trigger assistance and synchronize the device with the heart...
September 2017: Soft Robotics
Martin M LeWinter, Douglas Taatjes, Takamaru Ashikaga, Bradley Palmer, Nicole Bishop, Peter VanBuren, Stephen Bell, Cameron Donaldson, Markus Meyer, Kenneth B Margulies, Margaret Redfield, David A Bull, Michael Zile
Advanced glycation end-products (AGEs) play a role in the pathophysiology of diabetes mellitus (DM) and possibly hypertension (HTN). In experimental DM, AGEs accumulate in myocardium. Little is known about AGEs in human myocardium. We quantified abundance, localization, and functional correlates of the AGE carboxymethyl lysine (CML) in left ventricular (LV) myocardium from patients undergoing coronary bypass grafting (CBG). Immunoelectron microscopy was used to quantify CML in epicardial biopsies from 98 patients (71 M, 27 F) with HTN, HTN + DM or neither (controls), all with normal LV ejection fraction...
November 2017: Physiological Reports
Jagmohan Singh, Ipsita Mohanty, Satish Rattan
In these studies, we developed a novel approach of in vivo magnetofection for localized delivery of nucleic acids such as micro-RNA-139-5p (miR-139-5p; which is known to target Rho kinase2) to the circular smooth muscle layer of the internal anal sphincter (IAS). The IAS tone is known to play a major role in the rectoanal continence via activation of RhoA-associated kinase (RhoA/ROCK2). These studies established an optimized protocol for efficient gene delivery using an assembly of equal volumes of in vivo PolyMag and miR139-5p or anti-miR-139-5p (100 nM each) injected in the circular smooth muscle layer in the pinpointed areas of the rat perianal region and then incubated for 20 min under magnetic field...
January 1, 2018: American Journal of Physiology. Gastrointestinal and Liver Physiology
Diana A Monteiro, Edwin W Taylor, Francisco T Rantin, Ana L Kalinin
Metal pollutants have been considered one of the main factors underlying the depletion of biodiversity in natural populations unbalancing aquatic environments. The aim of this study was to evaluate the effects of exposure to inorganic Hg on myocardial contractility and the electrocardiogram (ECG) of two ecologically distinct Neotropical fish species, namely: matrinxã (Brycon amazonicus) and trahira (Hoplias malabaricus). Matrinxãs were exposed to a sublethal concentration of 0.1mgL-1 of Hg in water for 96h...
October 2017: Comparative Biochemistry and Physiology. Toxicology & Pharmacology: CBP
Matthew J Fuxjager, Meredith C Miles, Franz Goller, John Petersen, Julia Yancey
Steroid hormone action in the brain regulates many animals' elaborate social displays used for courtship and competition, but it is increasingly recognized that the periphery may also be a site for potent steroidal modulation of complex behavior. However, the mechanisms of such "bottom-up" regulation of behavioral outflow are largely unclear. To study this problem, we examined how androgenic sex hormones act through the skeletal muscular system to mediate elaborate courtship acrobatics in a tropical bird called the golden-collared manakin...
November 1, 2017: Endocrinology
Luc Leybaert, Paul D Lampe, Stefan Dhein, Brenda R Kwak, Peter Ferdinandy, Eric C Beyer, Dale W Laird, Christian C Naus, Colin R Green, Rainer Schulz
Connexins are ubiquitous channel forming proteins that assemble as plasma membrane hemichannels and as intercellular gap junction channels that directly connect cells. In the heart, gap junction channels electrically connect myocytes and specialized conductive tissues to coordinate the atrial and ventricular contraction/relaxation cycles and pump function. In blood vessels, these channels facilitate long-distance endothelial cell communication, synchronize smooth muscle cell contraction, and support endothelial-smooth muscle cell communication...
October 2017: Pharmacological Reviews
A Stępień, K Fabian, K Graff, M Podgurniak, A Wit
BACKGROUND: Impairment of spine rotation is a key concept in several theories explaining the pathogenesis and progression of scoliosis. In previous studies, a more limited range of motion in scoliotic girls compared to their non-scoliotic peers was noted. The Trunk-Pelvis-Hip Angle measurement is a test used to assess the range of motion in the trunk-pelvis-hip complex in the transverse plane. The aim of this study was to assess an immediate effect of Proprioceptive Neuromuscular Facilitation specific mobilization (mPNF) on the angle of trunk rotation and Trunk-Pelvis-Hip Angle range of motion in adolescent girls with double scoliosis...
2017: Scoliosis and Spinal Disorders
Yanfei Xie, Beibei Feng, Kedi Chen, Lars L Andersen, Phil Page, Yuling Wang
OBJECTIVE: To evaluate the efficacy of dynamic contract-relax stretching on delayed-onset muscle soreness (DOMS) in the calf muscle of healthy individuals. DESIGN: Randomized clinical trial. SETTING: Research laboratory. PARTICIPANTS: Three groups of 16 healthy participants (n = 48) were recruited by convenience sampling. INTERVENTIONS: Three sets of resisted bilateral heel-raising exercises until exhaustion were conducted to initiate DOMS...
July 21, 2017: Clinical Journal of Sport Medicine: Official Journal of the Canadian Academy of Sport Medicine
Qiang Zheng, Bojing Shi, Zhou Li, Zhong Lin Wang
Implantable medical devices (IMDs) have become indispensable medical tools for improving the quality of life and prolonging the patient's lifespan. The minimization and extension of lifetime are main challenges for the development of IMDs. Current innovative research on this topic is focused on internal charging using the energy generated by the physiological environment or natural body activity. To harvest biomechanical energy efficiently, piezoelectric and triboelectric energy harvesters with sophisticated structural and material design have been developed...
July 2017: Advanced Science (Weinheim, Baden-Wurttemberg, Germany)
Liisa M Blowes, Michaela Egertová, Yankai Liu, Graham R Davis, Nick J Terrill, Himadri S Gupta, Maurice R Elphick
The body wall of starfish is composed of magnesium calcite ossicles connected by collagenous tissue and muscles and it exhibits remarkable variability in stiffness, which is attributed to the mechanical mutability of the collagenous component. Using the common European starfish Asterias rubens as an experimental animal, here we have employed a variety of techniques to gain new insights into the structure of the starfish body wall. The structure and organisation of muscular and collagenous components of the body wall were analysed using trichrome staining...
September 2017: Journal of Anatomy
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 25, 2017: Proceedings of the National Academy of Sciences of the United States of America
Jiazhong Zhou, Sangjin Ryu, David Admiraal
Vorticella convallaria is a protozoan attached to a substrate by a stalk which can contract in less than 10 ms, translating the zooid toward the substrate with a maximum Reynolds number of ∼1. Following contraction, the stalk slowly relaxes, moving the zooid away from the substrate, which results in creeping flow. Although Vorticella has long been believed to contract to evade danger, it has been suggested that its stalk may contract to enhance food transport near the substrate. To elucidate how Vorticella utilizes its contraction-relaxation cycle, we investigated water flow caused by the cycle, using a computational fluid dynamics model validated with an experimental scale model and particle tracking velocimetry...
May 2017: Biomicrofluidics
Zhenyu Liu, Guofeng Wang
We used the first-principles density functional theory (DFT) to predict the magnetic properties of (1 0 0), (0 0 1), (1 0 1), (1 1 0), and (1 1 1) surfaces of L10 ordered CoPt alloy. Our results indicate that bulk-terminated CoPt surfaces exhibit magnetic moment higher than that of bulk CoPt crystal and surface magnetic anisotropy favoring in-plane magnetization. Moreover, our DFT calculations predict that Pt prefers to segregate to the outermost layer of all these five CoPt surfaces with energy gain in the range of 0...
September 6, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Nicholas T Kruse, William E Hughes, Kenichi Ueda, Darren P Casey
PURPOSE: The aim of this study was to examine whether independent effects exist between contractile work and metabolic demand (VO2m) on vasoconstrictor responsiveness (i.e., functional sympatholysis) under different contraction durations matched for total contractile work in exercising human skeletal muscle. METHODS: Ten young men performed rhythmic forearm contractions at 10 and 15% of maximum voluntary contraction (MVC) which consisted of muscle contractions using the same duty cycle but altering the duration of the contraction-relaxation cycles of exercise and included: 1) fast frequency contractions at 10% MVC (FFC10%) using a contraction relaxation cycle at 1:2 s; 2) slow frequency contractions at 10% MVC (SFC10%) at 2:4 s; and 3) SFC at 15% MVC (SFC15%) at 2:4 s...
August 2017: European Journal of Applied Physiology
Pasquale Chitano, Lu Wang, Gabrielle Y Y Tin, Mitsuo Ikebe, Peter D Paré, Chun Y Seow
Smooth muscle is able to function over a much broader length range than striated muscle. The ability to maintain contractility after a large length change is thought to be due to an adaptive process involving restructuring of the contractile apparatus to maximize overlap between the contractile filaments. The molecular mechanism for the length-adaptive behavior is largely unknown. In smooth muscle adapted to different lengths we quantified myosin monomers, basal and activation-induced myosin light chain (MLC) phosphorylation, shortening velocity, power output and active force...
August 1, 2017: Journal of Cell Science
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