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https://www.readbyqxmd.com/read/28428008/force-development-and-intracellular-ca-2-in-intact-cardiac-muscles-from-gravin-mutant-mice
#1
Zhitao Li, Sonal Singh, Santosh V Suryavanshi, Wengang Ding, Xiaoxu Shen, Cori S Wijaya, Wei Dong Gao, Bradley K McConnell
Gravin (AKAP12) is an A-kinase-anchoring-protein that scaffolds protein kinase A (PKA), β2-adrenergic receptor (β2-AR), protein phosphatase 2B and protein kinase C. Gravin facilitates β2-AR-dependent signal transduction through PKA to modulate cardiac excitation-contraction coupling and its removal positively affects cardiac contraction. Trabeculae from the right ventricles of gravin mutant (gravin-t/t) mice were employed for force determination. Simultaneously, corresponding intracellular Ca(2+) transient ([Ca(2+)]i) were measured...
April 17, 2017: European Journal of Pharmacology
https://www.readbyqxmd.com/read/28427997/distinct-sequences-and-post-translational-modifications-in-cardiac-atrial-and-ventricular-myosin-light-chains-revealed-by-top-down-mass-spectrometry
#2
Zachery R Gregorich, Wenxuan Cai, Ziqing Lin, Albert J Chen, Ying Peng, Takushi Kohmoto, Ying Ge
Myosin is the principal component of the thick filaments that, through interactions with the actin thin filaments, mediates force production during muscle contraction. Myosin is a hexamer, consisting of two heavy chains, each associated with an essential (ELC) and a regulatory (RLC) light chain, which bind the lever-arm of the heavy chain and play important modulatory roles in striated muscle contraction. Nevertheless, a comprehensive assessment of the sequences of the ELC and RLC isoforms, as well as their post-translational modifications, in the heart remains lacking...
April 17, 2017: Journal of Molecular and Cellular Cardiology
https://www.readbyqxmd.com/read/28423017/auxotonic-to-isometric-contraction-transitioning-in-a-beating-heart-causes-myosin-step-size-to-down-shift
#3
Thomas P Burghardt, Xiaojing Sun, Yihua Wang, Katalin Ajtai
Myosin motors in cardiac ventriculum convert ATP free energy to the work of moving blood volume under pressure. The actin bound motor cyclically rotates its lever-arm/light-chain complex linking motor generated torque to the myosin filament backbone and translating actin against resisting force. Previous research showed that the unloaded in vitro motor is described with high precision by single molecule mechanical characteristics including unitary step-sizes of approximately 3, 5, and 8 nm and their relative step-frequencies of approximately 13, 50, and 37%...
2017: PloS One
https://www.readbyqxmd.com/read/28419739/cardiac-troponin-t-and-fast-skeletal-muscle-denervation-in-ageing
#4
Zherong Xu, Xin Feng, Juan Dong, Zhong-Min Wang, Jingyun Lee, Cristina Furdui, Daniel Clark Files, Kristen M Beavers, Stephen Kritchevsky, Carolanne Milligan, Jian-Ping Jin, Osvaldo Delbono, Tan Zhang
BACKGROUND: Ageing skeletal muscle undergoes chronic denervation, and the neuromuscular junction (NMJ), the key structure that connects motor neuron nerves with muscle cells, shows increased defects with ageing. Previous studies in various species have shown that with ageing, type II fast-twitch skeletal muscle fibres show more atrophy and NMJ deterioration than type I slow-twitch fibres. However, how this process is regulated is largely unknown. A better understanding of the mechanisms regulating skeletal muscle fibre-type specific denervation at the NMJ could be critical to identifying novel treatments for sarcopenia...
April 16, 2017: Journal of Cachexia, Sarcopenia and Muscle
https://www.readbyqxmd.com/read/28413031/matrix-metalloproteinases-in-remodeling-of-lower-extremity-veins-and-chronic-venous-disease
#5
Yunfei Chen, Wei Peng, Joseph D Raffetto, Raouf A Khalil
The veins of the lower extremity are equipped with efficient wall, contractile vascular smooth muscle (VSM), and competent valves in order to withstand the high venous hydrostatic pressure in the lower limb and allow unidirectional movement of deoxygenated blood toward the heart. The vein wall structure and function are in part regulated by matrix metalloproteinases (MMPs). MMPs are zinc-dependent endopeptidases that are secreted as inactive pro-MMPs by different cells in the venous wall including fibroblasts, VSM, and leukocytes...
2017: Progress in Molecular Biology and Translational Science
https://www.readbyqxmd.com/read/28410968/increase-in-serum-noradrenaline-concentration-by-short-dives-with-bradycardia-in-indo-pacific-bottlenose-dolphin-tursiops-aduncus
#6
Miwa Suzuki, Mika Tomoshige, Miki Ito, Sotaro Koga, Makio Yanagisawa, Takashi Bungo, Yuya Makiguchi
In cetaceans, diving behavior immediately induces a change in blood circulation to favor flow to the brain and heart; this is achieved by intense vasoconstriction of the blood vessels that serve other organs. This blood circulation response is allied to a decrease in heart rate in order to optimize oxygen usage during diving. Vasoconstrictors are present in all mammals and stimulate the contraction of the smooth muscle in the walls of blood vessels. The most important of these vasoconstrictors are the hormones adrenaline (A), noradrenaline (NA), and angiotensin II (ANG II)...
April 11, 2017: General and Comparative Endocrinology
https://www.readbyqxmd.com/read/28381456/muscle-mechanoreflex-activation-via-passive-calf-stretch-causes-renal-vasoconstriction-in-healthy-humans
#7
Rachel C Drew, Cheryl A Blaha, Michael D Herr, Ruda Cui, Lawrence I Sinoway
Reflex renal vasoconstriction occurs during exercise, and renal vasoconstriction in response to upper-limb muscle mechanoreflex activation has been documented. However, the renal vasoconstrictor response to muscle mechanoreflex activation originating from lower limbs, with and without local metabolite accumulation, has not been assessed. Eleven healthy young subjects (26 ± 1y; 5 men) underwent two trials involving 3-min passive calf muscle stretch (mechanoreflex) during 7.5-min lower-limb circulatory occlusion (CO)...
April 5, 2017: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/28381455/2015-ludwig-lecture-abnormal-cardiovascular-responses-to-exercise-in-hypertension-contribution-of-neural-factors
#8
Jere Holloway Mitchell
During both dynamic (e.g. endurance) and static (e.g. strength) exercise there are exaggerated cardiovascular responses in hypertension. This includes greater increases in blood pressure, heart rate, and efferent sympathetic nerve activity than in normals. Two of the known neural factors which contribute to this abnormal cardiovascular response are the exercise pressor reflex (EPR) and functional sympatholysis. The EPR originates in contracting skeletal muscle and reflexly increases sympathetic efferent nerve activity to the heart and blood vessels as well as decreases parasympathetic efferent nerve activity to the heart...
April 5, 2017: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/28369936/the-role-played-by-oxidative-stress-in-evoking-the-exercise-pressor-reflex-in-health-and-simulated-peripheral-artery-disease
#9
Jonathan E Harms, J Matthew Kuczmarski, Joyce Kim, Gail D Thomas, Marc P Kaufman
Contraction of muscle evokes the exercise pressor reflex (EPR), which is expressed partly by increases in heart rate and arterial pressure. Patients with peripheral artery disease (PAD) show an exaggerated EPR, sometimes report pain when walking and are at risk for cardiac arrthymias. Previous research suggested that reactive oxygen species (ROS) mediate the exaggerated EPR associated with PAD. To examine the effects of ROS on the EPR, we infused a superoxide scavenger, tiron, into the superficial epigastric artery of decerebrated rats...
March 28, 2017: Journal of Physiology
https://www.readbyqxmd.com/read/28366003/complete-characterization-of-cardiac-myosin-heavy-chain-223-kda-enabled-by-size-exclusion-chromatography-and-middle-down-mass-spectrometry
#10
Yutong Jin, Liming Wei, Wenxuan Cai, Ziqing Lin, Zhijie Wu, Ying Peng, Takushi Kohmoto, Richard L Moss, Ying Ge
Myosin heavy chain (MHC), the major component of myosin motor molecule, plays an essential role in force production during muscle contraction. However, a comprehensive analysis of MHC proteoforms arising from sequence variations and post-translational modifications (PTMs) remains challenging due to the difficulties in purifying MHC (~223 kDa) and achieving complete sequence coverage. Herein, we have established a strategy to effectively purify and comprehensively characterize MHC from heart tissue by combining size-exclusion chromatography (SEC) and middle-down mass spectrometry (MS)...
April 1, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28365405/novel-insights-into-cardiac-remodelling-revealed-by-proteomic-analysis-of-the-trout-heart-during-exercise-training
#11
Laura A Dindia, Sarah L Alderman, Todd E Gillis
The changes in the cardiac proteome of rainbow trout (Oncorhynchus mykiss) were quantified during the early phases (4, 7, and 14d) of a typical exercise-training regime to provide a comprehensive overview of the cellular changes responsible for developing a trained heart phenotype. Enhanced somatic growth during the 14d experiment was paralleled by cardiac growth to maintain relative ventricular mass. This was reflected in the cardiac proteome by the increased abundance of contractile proteins and cellular integrity proteins as early as Day 4, including a pronounced and sustained increase in blood vessel epicardial substance - an intercellular adhesion protein expressed in the vertebrate heart...
March 29, 2017: Journal of Proteomics
https://www.readbyqxmd.com/read/28342525/-cardiac-hydatid-cyst-which-imaging-modality-for-an-accurate-diagnosis
#12
A Ben Khalfallah, H Ben Slima
Cardiac echinococcosis is rare. Its spontaneous course is serious because of the risk of rupture. Its clinical manifestations are variable, often latent and misleading. The diagnosis is sometimes referred to by chest radiography. It is much facilitated by non-invasive imaging techniques in particular transesophageal and transthoracic echocardiography, CT scan and magnetic resonance imaging. The latter through a morphological and topographical analysis accurate diagnosis of hydatid cyst and its relationship to cardiac muscle and surrounding tissue...
March 22, 2017: Annales de Cardiologie et D'angéiologie
https://www.readbyqxmd.com/read/28337151/a-reduction-in-maximal-incremental-exercise-test-duration-48-h-post-downhill-run-is-associated-with-muscle-damage-derived-exercise-induced-pain
#13
Bryna C R Chrismas, Lee Taylor, Jason C Siegler, Adrian W Midgley
Purpose: To examine whether exercise induced muscle damage (EIMD) and muscle soreness reduce treadmill maximal incremental exercise (MIE) test duration, and true maximal physiological performance as a consequence of exercise induced pain (EIP) and perceived effort. Methods: Fifty (14 female), apparently healthy participants randomly allocated into a control group (CON, n = 10), or experimental group (EXP, n = 40) visited the laboratory a total of six times: visit 1 (familiarization), visit 2 (pre 1), visit 3 (pre 2), visit 4 (intervention), visit 5 (24 h post) and visit 6 (48 h post)...
2017: Frontiers in Physiology
https://www.readbyqxmd.com/read/28301285/wireless-power-transfer-for-a-pacemaker-application
#14
Vladimir Vulfin, Shai Sayfan-Altman, Reuven Ianconescu
An artificial pacemaker is a small medical device that uses electrical impulses, delivered by electrodes contracting the heart muscles, to regulate the beating of the heart. The pacemaker is implanted under the skin, and uses for many years regular non-rechargeable batteries. However, the demand for rechargeable batteries in pacemakers increased, and the aim of this work is to design an efficient charging system for pacemakers.
March 16, 2017: Journal of Medical Engineering & Technology
https://www.readbyqxmd.com/read/28278300/physical-activity-levels-determine-exercise-induced-changes-in-brain-excitability
#15
Tea Lulic, Jenin El-Sayes, Hunter J Fassett, Aimee J Nelson
Emerging evidence suggests that regular physical activity can impact cortical function and facilitate plasticity. In the present study, we examined how physical activity levels influence corticospinal excitability and intracortical circuitry in motor cortex following a single session of moderate intensity aerobic exercise. We aimed to determine whether exercise-induced short-term plasticity differed between high versus low physically active individuals. Participants included twenty-eight young, healthy adults divided into two equal groups based on physical activity level determined by the International Physical Activity Questionnaire: low-to-moderate (LOW) and high (HIGH) physical activity...
2017: PloS One
https://www.readbyqxmd.com/read/28254082/ecg-artifact-cancellation-in-surface-emg-signals-by-fractional-order-calculus-application
#16
Nadica Miljković, Nenad Popović, Olivera Djordjević, Ljubica Konstantinović, Tomislav B Šekara
BACKGROUND AND OBJECTIVE: New aspects for automatic electrocardiography artifact removal from surface electromyography signals by application of fractional order calculus in combination with linear and nonlinear moving window filters are explored. Surface electromyography recordings of skeletal trunk muscles are commonly contaminated with spike shaped artifacts. This artifact originates from electrical heart activity, recorded by electrocardiography, commonly present in the surface electromyography signals recorded in heart proximity...
March 2017: Computer Methods and Programs in Biomedicine
https://www.readbyqxmd.com/read/28223172/a-simple-model-of-cardiac-muscle-for-multiscale-simulation-passive-mechanics-crossbridge-kinetics-and-calcium-regulation
#17
Fyodor A Syomin, Andrey K Tsaturyan
A simple model of cardiac muscle was designed for multiscale simulation of heart mechanics. Relaxed cardiac muscle was described as a transversally isotropic hyperelastic material. Active tension caused by actin-myosin crossbridges depends on the ensemble averaged strain of myosin heads bound to actin. Calcium activation was modeled by Ca(2+) binding to troponin-C. To account for the dependence of troponin affinity for Ca(2+) on myosin heads strongly bound to actin, the kinetics of troponin binding to Ca(2+) in the overlap zone of the thin and thick filaments and outside it were separated...
February 20, 2017: Journal of Theoretical Biology
https://www.readbyqxmd.com/read/28188199/back-to-the-future-revisiting-the-physiological-cost-of-negative-work-as-a-team-based-activity-for-exercise-physiology-students
#18
Matthew A Kilgas, Steven J Elmer
We implemented a team-based activity in our exercise physiology teaching laboratory that was inspired from Abbott et al.'s classic 1952 Journal of Physiology paper titled "The physiological cost of negative work." Abbott et al. connected two bicycles via one chain. One person cycled forward (muscle shortening contractions, positive work) while the other resisted the reverse moving pedals (muscle lengthening contractions, negative work), and the cost of work was compared. This study was the first to link human whole body energetics with isolated muscle force-velocity characteristics...
March 1, 2017: Advances in Physiology Education
https://www.readbyqxmd.com/read/28182797/can-real-time-visual-feedback-during-gait-retraining-reduce-metabolic-demand-for-individuals-with-transtibial-amputation
#19
Elizabeth Russell Esposito, Harmony S Choi, Benjamin J Darter, Jason M Wilken
The metabolic demand of walking generally increases following lower extremity amputation. This study used real-time visual feedback to modify biomechanical factors linked to an elevated metabolic demand of walking in individuals with transtibial amputation. Eight persons with unilateral, traumatic transtibial amputation and 8 uninjured controls participated. Two separate bouts of real-time visual feedback were provided during a single session of gait retraining to reduce 1) center of mass sway and 2) thigh muscle activation magnitudes and duration...
2017: PloS One
https://www.readbyqxmd.com/read/28174436/cardiovascular-response-to-bouts-of-exercise-with-blood-flow-restriction
#20
Kestutis Bunevicius, Arturas Sujeta, Kristina Poderiene, Birute Zachariene, Viktoras Silinskas, Rimantas Minkevicius, Jonas Poderys
[Purpose] Occlusion training with low-intensity resistance exercises and blood flow restriction increases muscle cross-sectional area and strength. This form of training is used in rehabilitation; therefore, the aim of this study was to examine the effect of one occlusion training session on the cardiovascular response to bouts of exercise. [Subjects and Methods] Two groups took part: a control group without blood flow restriction and an experimental group with blood flow restriction. A single training session was used with the exercise intensity set at 40% of the one repetition maximum...
December 2016: Journal of Physical Therapy Science
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