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Muscle co contraction

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https://www.readbyqxmd.com/read/28444807/rkip-lessons-of-a-better-way-for-%C3%AE-adrenergic-receptor-activation-in-the-heart
#1
Kristina Lorenz, Marsha Rich Rosner, Theresa Brand, Joachim P Schmitt
Stimulation of β-adrenergic receptors (βAR) provides the most efficient physiological mechanism to enhance contraction and relaxation of the heart. Activation of βAR allows rapid enhancement of myocardial function in order to fuel the muscles for running and fighting in a fight-or-flight response. Likewise, βAR get activated during cardiovascular disease in an attempt to counteract the restrictions of cardiac output. However, long-term stimulation of βAR increases the likelihood of cardiac arrhythmias, adverse ventricular remodelling, decline of cardiac performance and premature death, thereby limiting the use of βAR agonists in the treatment of heart failure...
April 26, 2017: Journal of Physiology
https://www.readbyqxmd.com/read/28433389/comparison-of-methodologies-to-assess-muscle-co-contraction-during-gait
#2
H Souissi, R Zory, J Bredin, P Gerus
The aim of this study was to compare co-contraction index (CCI) computed from muscle moments to different co-activation indexes (Co-Act) derived from EMG data at the ankle and the knee joint during gait. An EMG-driven model was used to estimate muscle moments during over-ground walking gait at a self-selected velocity from twelve healthy subjects. The CCI calculated from muscle moments was compared with three Co-Acts estimated from the normalized EMG data. The co-activation methods produced lower values than the CCI during the first double-support and the swing phase at the ankle joint and during the stance phase at the knee joint...
April 9, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28430879/role-of-phosphatase-and-tensin-homolog-pten-in-hypoxic-pulmonary-vasoconstriction
#3
Adrienn Krauszman, Tak Mak, Katalin Szaszi, Wolfgang M Kuebler
AIMS: Hypoxic pulmonary vasoconstriction (HPV) redistributes blood flow from poorly ventilated to better aerated areas in the lung, thereby optimizing ventilation-perfusion ratio (V/Q). Pulmonary artery smooth muscle cell (PASMC) contraction in response to hypoxia is triggered by Ca2+ influx via transient receptor potential canonical 6 (TRPC6) cation channels that have translocated to caveolae in the plasma membrane. Since phosphatase and tensin homolog (PTEN) was suggested to regulate TRPC6 in endothelial cells, we aimed to define its role in the hypoxic response of PASMCs and as a putative mediator of HPV...
April 18, 2017: Cardiovascular Research
https://www.readbyqxmd.com/read/28423914/current-views-on-neuropeptide-y-and-diabetes-related-atherosclerosis
#4
Wei-Wei Sun, Ping Zhu, Yan-Chuan Shi, Chen-Liang Zhang, Xu-Feng Huang, Shi-Yu Liang, Zhi-Yuan Song, Shu Lin
Diabetes-induced atherosclerotic cardiovascular disease is the leading cause of death of diabetic patients. Neuronal regulation plays a critical role in glucose metabolism and cardiovascular function under physiological and pathological conditions, among which, neurotransmitter neuropeptide Y has been shown to be closely involved in these two processes. Elevated central neuropeptide Y level promotes food intake and reduces energy expenditure, thereby increasing adiposity. Neuropeptide Y is co-localized with noradrenaline in central and sympathetic nervous systems...
April 1, 2017: Diabetes & Vascular Disease Research
https://www.readbyqxmd.com/read/28420971/dynamic-increase-in-corticomuscular-coherence-during-bilateral-cyclical-ankle-movements
#5
Takashi Yoshida, Kei Masani, Karl Zabjek, Robert Chen, Milos R Popovic
In humans, the midline primary motor cortex is active during walking. However, the exact role of such cortical participation is unknown. To delineate the role of the primary motor cortex in walking, we examined whether the primary motor cortex would activate leg muscles during movements that retained specific requirements of walking (i.e., locomotive actions). We recorded electroencephalographic and electromyographic signals from 15 healthy, young men while they sat and performed bilateral, cyclical ankle movements...
2017: Frontiers in Human Neuroscience
https://www.readbyqxmd.com/read/28420761/in-situ-measurements-of-tensile-forces-in-the-tibialis-anterior-tendon-of-the-rat-in-concentric-isometric-and-resisted-co-contractions
#6
Martin Schmoll, Ewald Unger, Hazel Sutherland, Michael Haller, Manfred Bijak, Hermann Lanmüller, Jonathan C Jarvis
Tensile-force transmitted by the tibialis anterior (TA) tendon of 11 anesthetized adult male Wistar rats (body-mass: 360.6 ± 66.3 g) was measured in-situ within the intact biomechanical system of the hind-limb using a novel miniature in-line load-cell. The aim was to demonstrate the dependence of the loading-profile experienced by the muscle, on stimulation-frequency and the resistance to shortening in a group of control-animals. Data from these acute-experiments shows the type of loading achievable by means of implantable electrical stimulators activating agonists or agonist/antagonist groups of muscles during programmed resistance-training in freely moving healthy subjects...
April 2017: Physiological Reports
https://www.readbyqxmd.com/read/28412748/tumor-necrosis-factor-receptor-2-akt-and-erk-signaling-pathways-contribute-to-the-switch-from-fibroblasts-to-cafs-by-progranulin-in-microenvironment-of-colorectal-cancer
#7
Linlin Wang, Dong Yang, Jing Tian, Aiqin Gao, Yihang Shen, Xia Ren, Xia Li, Guosheng Jiang, Taotao Dong
Cancer associated fibroblasts (CAFs) are a crucial cellular component in tumor microenvironment and could promote tumor progression. CAFs are usually derived from resident fibroblasts, which undergoing an activated process stimulated by tumor cells. However, the agents and mechanism driving this switch have not yet been elucidated. Progranulin (PGRN), a well acknowledged secreted glycoprotein, could promote proliferation and angiogenesis of colorectal cancer (CRC) cells, and high expression of PGRN correlated with patient poor prognosis...
February 17, 2017: Oncotarget
https://www.readbyqxmd.com/read/28411442/ankle-muscle-co-contractions-during-quiet-standing-are-associated-with-decreased-postural-steadiness-in-the-elderly
#8
Albert H Vette, Dimitry G Sayenko, Michael Jones, Masaki O Abe, Kimitaka Nakazawa, Kei Masani
It has been reported that the elderly use co-contraction of the tibialis anterior (TA) and plantarflexor muscles for longer duration during quiet standing than the young. However, the particular role of ankle muscle co-contractions in the elderly during quiet standing remains unclear. Therefore, the objective of this study was to investigate the association between ankle muscle co-contractions and postural steadiness during standing in the elderly. Twenty-seven young (27.2±4.5yrs) and twenty-three elderly (66...
April 5, 2017: Gait & Posture
https://www.readbyqxmd.com/read/28409828/leucine-elicits-myotube-hypertrophy-and-enhances-maximal-contractile-force-in-tissue-engineered-skeletal-muscle-in-vitro
#9
N R W Martin, M C Turner, R Farrington, D J Player, M P Lewis
The amino acid leucine is thought to be important for skeletal muscle growth by virtue of its ability to acutely activate mTORC1 and enhance muscle protein synthesis, yet little data exist regarding its impact on skeletal muscle size and its ability to produce force. We utilised a tissue engineering approach in order to test whether supplementing culture medium with leucine could enhance mTORC1 signalling, myotube growth and muscle function. Phosphorylation of the mTORC1 target proteins 4EBP-1 and rpS6 and myotube hypertrophy appeared to occur in a dose dependent manner, with 5 and 20mM of leucine inducing similar effects, which were greater than those seen with 1mM...
April 14, 2017: Journal of Cellular Physiology
https://www.readbyqxmd.com/read/28381456/muscle-mechanoreflex-activation-via-passive-calf-stretch-causes-renal-vasoconstriction-in-healthy-humans
#10
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/28379296/relaxin-treatment-reduces-angiotensin-ii-induced-vasoconstriction-in-pregnancy-and-protects-against-endothelial-dysfunction
#11
Sarah A Marshall, Chen Huei Leo, Jane E Girling, Marianne Tare, Sally Beard, Natalie J Hannan, Laura J Parry
The peptide relaxin has gained considerable attention as a new vasoactive drug, largely through its beneficial therapeutic effects in cardiovascular disease. In this study, we tested the hypothesis that relaxin treatment alleviates systemic vascular dysfunction characteristic of hypertensive diseases of pregnancy. We investigated vascular effects and mechanisms of relaxin action in: i) pregnant relaxin-deficient (Rln-/-) mice with enhanced responses to angiotensin II (AngII), and ii) arteries pre-incubated ex vivo in trophoblast conditioned media (TCM) to induce endothelial dysfunction...
April 3, 2017: Biology of Reproduction
https://www.readbyqxmd.com/read/28350712/effect-of-knee-joint-angle-and-contraction-intensity-on-hamstrings-coactivation
#12
Rui Wu, Eamonn Delahunt, Massimiliano Ditroilo, Madeleine Lowery, Giuseppe De Vito
PURPOSE: This study investigated the effect of knee joint angle and contraction intensity on the co-activation of the hamstring muscles (when acting as antagonists to the quadriceps) in young and older individuals of both sexes. METHODS: 25 young (24 ± 2.6 years) and 26 older (70 ± 2.5 years) healthy men and women participated. Maximal voluntary isometric contraction (MVIC) of the knee extensors (KE) and flexors was assessed at two knee joint angles (90° and 60°, 0° = full extension)...
March 27, 2017: Medicine and Science in Sports and Exercise
https://www.readbyqxmd.com/read/28336812/tgf-%C3%AE-1-stimulates-hdac4-nucleus-to-cytoplasm-translocation-and-nadph-oxidase4-derived-reactive-oxygen-species-in-normal-human-lung-fibroblasts
#13
Weichao Guo, Shigeki Saito, Cecilia G Sanchez, Yan Zhuang, Rafael E Gongora Rosero, Bin Shan, Fayong Luo, Joseph A Lasky
Myofibroblasts are important mediators of fibrogenesis, thus blocking fibroblast to myofibroblast differentiation (FMD) may be an effective strategy to treat pulmonary fibrosis (PF). Previously we reported that HDAC4 activity is necessary for TGF-β1-induced human lung FMD. Here we show that TGF-β1 increases NOX4 mRNA and protein expression in normal human lung fibroblasts (NHLFs) and causes nuclear export of HDAC4. Application of the NOX family inhibitor, diphenyleneiodonium chloride (DPI), reduces TGF-β1-induced HDAC4 nuclear export, expression of the myofibroblast marker α-smooth muscle actin (α-SMA), and α-SMA fiber formation...
March 23, 2017: American Journal of Physiology. Lung Cellular and Molecular Physiology
https://www.readbyqxmd.com/read/28329460/model-based-comparison-of-the-normal-and-fontan-circulatory-systems-part-iii
#14
Raymond L Watrous, Alvin J Chin
BACKGROUND: For patients with the Fontan circulatory arrangement, angiotensin-converting enzyme inhibition, guanylate cyclase activation, phosphodiesterase 5 inhibition, and endothelin receptor antagonism have so far resulted in little or no improvement in [Formula: see text] or peak cardiac index (CI), suggesting that our understanding of the factors that most impact the exercise hemodynamics is incomplete. METHODS: To facilitate comparisons with clinical reports of the exercise performance of preadolescent Fontan patients, we rescaled our previously reported computational models of a two-year-old normal child and similarly aged Fontan patient, extended our Fontan model to capture the nonlinear relationship between flow and resistance quantified from previous computational fluid dynamic analyses of the total cavopulmonary connection (TCPC), and added respiration as well as skeletal muscle contraction...
March 2017: World Journal for Pediatric & Congenital Heart Surgery
https://www.readbyqxmd.com/read/28326563/early-structural-and-functional-signature-of-3-day-human-skeletal-muscle-disuse-using-the-dry-immersion-model
#15
Rémi Demangel, Loïc Treffel, Guillaume Py, Thomas Brioche, Allan F Pagano, Marie-Pierre Bareille, Arnaud Beck, Laurence Pessemesse, Robin Candau, Claude Gharib, Angèle Chopard, Catherine Millet
KEY POINTS: Our study contributes to the characterization of muscle loss and weakness processes induced by a sedentary life style, chronic hypoactivity, clinical bed rest, immobilization and microgravity. This study, by bringing together integrated and cellular evaluation of muscle structure and function, identifies the early functional markers and biomarkers of muscle deconditioning. Three days of muscle disuse in healthy adult subjects is sufficient to significantly decrease muscle mass, tone and force, and to induce changes in function relating to a weakness in aerobic metabolism and muscle fibre denervation...
March 22, 2017: Journal of Physiology
https://www.readbyqxmd.com/read/28324993/dynamic-knee-muscle-co-contraction-quantified-during-walking
#16
Annachiara Strazza, Alessandro Mengarelli, Valentina Agostini, Marco Knaflitz, Laura Burattini, Sandro Fioretti, Francesco Di Nardo
The purpose of the present study was the quantification of the co-activation patterns of the knee extensor and flexor muscles during walking at self-selected speed and cadence. To this aim, the Statistical Gait Analysis, a recent methodology providing a statistical characterization of gait, was performed on surface EMG signals from Vastus Lateralis (VL) and Medial Hamstrings (MH) in 14 healthy young adult subjects. Muscular co-contraction was assessed as the overlapping period between activation intervals of agonist and antagonist muscles...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28319133/effects-of-sudden-walking-perturbations-on-neuromuscular-reflex-activity-and-three-dimensional-motion-of-the-trunk-in-healthy-controls-and-back-pain-symptomatic-subjects
#17
Juliane Mueller, Tilman Engel, Steffen Mueller, Josefine Stoll, Heiner Baur, Frank Mayer
BACKGROUND: Back pain patients (BPP) show delayed muscle onset, increased co-contractions, and variability as response to quasi-static sudden trunk loading in comparison to healthy controls (H). However, it is unclear whether these results can validly be transferred to suddenly applied walking perturbations, an automated but more functional and complex movement pattern. There is an evident need to develop research-based strategies for the rehabilitation of back pain. Therefore, the investigation of differences in trunk stability between H and BPP in functional movements is of primary interest in order to define suitable intervention regimes...
2017: PloS One
https://www.readbyqxmd.com/read/28279980/glucose-transporter-4-glut4-is-not-necessary-for-overload-induced-glucose-uptake-or-hypertrophic-growth-in-mouse-skeletal-muscle
#18
Shawna L McMillin, Denise L Schmidt, Barbara B Kahn, Carol A Witczak
Glucose transporter 4 (GLUT4) is necessary for acute insulin- and contraction-induced skeletal muscle glucose uptake, but its role in chronic muscle loading (overload)-induced glucose uptake is unknown. Our goal was to determine if GLUT4 is required for overload-induced glucose uptake. Overload was induced in mouse plantaris muscle by unilateral synergist ablation. After 5 days, muscle weights and ex vivo [(3)H]-2-deoxy-D-glucose uptake were assessed. Overload-induced muscle glucose uptake and hypertrophic growth were not impaired in muscle-specific GLUT4 knockout mice, demonstrating that GLUT4 is not necessary for these processes...
March 9, 2017: Diabetes
https://www.readbyqxmd.com/read/28277422/neuromuscular-adaptations-to-short-term-high-intensity-interval-training-in-female-ice-hockey-players
#19
Juho-Ville Kinnunen, Harri Piitulainen, Jarmo M Piirainen
High-intensity interval training (HIIT) related neuromuscular adaptations, changes in force production and on-ice performance were investigated in female ice-hockey players during pre-season. Fourteen Finnish championship level ice hockey players (average age 22 ± 3 years) participated in 2½-week HIIT. Both spinal (H-reflex) and supraspinal (V-wave) neuromuscular responses of the soleus muscle were recorded before and after the training period. Static jump (SJ) and countermovement jump (CMJ) heights, plantar flexor maximal voluntary contraction (MVC) and rate of force development (RFD) were measured...
March 8, 2017: Journal of Strength and Conditioning Research
https://www.readbyqxmd.com/read/28268974/neuromotor-response-of-the-leg-muscles-following-a-supine-stand-retraining-with-without-neuromuscular-electrical-stimulation-training-intervention-for-individuals-with-sci-a-case-series
#20
Stephen Canton, Kamyar Momeni, Arvind Ramanujam, Erica Garbarini, Gail F Forrest
The goal of this paper is to study the effects of supine and stand retraining (SRT) interventions with and without multi muscle neuromuscular electrical stimulation (NMES) on the neuromuscular EMG responses of the leg muscles for individuals with motor complete SCI during walking on a body-weight support (BWS) treadmill. The main outcome variables were EMG amplitude, integrated EMG and co-contraction indices (co-excitation and co-activation) collected during a 10-minute walking treadmill trial. Data was analyzed for the first, fifth and tenth minute of walking...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
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