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Fast twitch

Pavlos E Evangelidis, Garry J Massey, Richard A Ferguson, Patrick C Wheeler, Matthew T G Pain, Jonathan P Folland
Hamstrings muscle fiber composition may be predominantly fast-twitch and could explain the high incidence of hamstrings strain injuries. However, hamstrings muscle composition in vivo, and its influence on knee flexor muscle function, remains unknown. We investigated biceps femoris long head (BFlh) myosin heavy chain (MHC) composition from biopsy samples, and the association of hamstrings composition and hamstrings muscle volume (using MRI) with knee flexor maximal and explosive strength. Thirty-one young men performed maximal (concentric, eccentric, isometric) and explosive (isometric) contractions...
October 13, 2016: Scandinavian Journal of Medicine & Science in Sports
Malek Kammoun, Philippe Pouletaut, Francis Canon, Malayannan Subramaniam, John R Hawse, Muriel Vayssade, Sabine F Bensamoun
As transforming growth factor (TGF)-β inducible early gene-1 is highly expressed in skeletal muscle, the effect of TIEG1 gene deletion on the passive mechanical properties of slow and fast twitch muscle fibers was analyzed. Twenty five muscle fibers were harvested from soleus (Sol) and extensor digitorum longus (EDL) muscles from TIEG1-/- (N = 5) and control (N = 5) mice. Mechanical tests were performed on fibers and the dynamic and static stresses were measured. A viscoelastic Hill model of 3rd order was used to fit the experimental relaxation test data...
2016: PloS One
Yoo Kim, Daeyoung Kim, Yeonhwa Park
Previously, it was reported that conjugated linoleic acid (CLA) with exercise training potentially improved endurance capacity via the peroxisome proliferator-activated receptor δ (PPARδ)-mediated mechanism in mice. This study determined the role of exercise and/or CLA in endurance capacity and PPARδ-associated regulators. Male 129Sv/J mice were fed either control (soybean oil) or CLA (0.5%) containing diets for 4 weeks and were further divided into sedentary or training regimes. CLA supplementation significantly reduced body weight and fat mass independent of exercise during the experimental period...
September 7, 2016: Journal of Nutritional Biochemistry
Alba Chacon-Cabrera, Joaquim Gea, Esther Barreiro
Skeletal muscle dysfunction and atrophy are characteristic features accompanying chronic conditions. Epigenetic events regulate muscle mass and function maintenance. We hypothesized that the pattern of epigenetic events (muscle-enriched microRNAs and histone acetylation) and acetylation of transcription factors known to signal muscle wasting may differ between early- and late-time points in skeletal muscles of mice exposed to hindlimb immobilization (I) and recovery following I. Body and muscle weights, grip strength, muscle-enriched microRNAs, histone deacetylases (HDACs), acetylation of proteins, histones, and transcription factors (TF), myogenic TF factors, and muscle phenotype were assessed in gastrocnemius of mice exposed to periods (1, 2, 3, 7, 15 and 30 days, I groups) of hindlimb immobilization, and in those exposed to reloading for different periods of time (1, 3, 7, 15, and 30 days, R groups) following 7-day immobilization...
October 7, 2016: Journal of Cellular Physiology
Henry G Zot, Javier E Hasbun
To explain disparate decay rates of cytosolic Ca(2+) and structural changes in the thin filaments during a twitch, we model the time course of Ca(2+)-bound troponin (Tn) resulting from the free Ca(2+) transient of fast skeletal muscle. In fibers stretched beyond overlap, the decay of Ca(2+) as measured by a change in fluo-3 fluorescence is significantly slower than the intensity decay of the meridional 1/38.5 nm(-1) reflection of Tn; this is not simply explained by considering only the Ca(2+) binding properties of Tn alone (Matsuo et al...
2016: Frontiers in Physiology
Mitchell A Frankel, V John Mathews, Gregory A Clark, Richard A Normann, Sanford G Meek
Asynchronous intrafascicular multi-electrode stimulation (aIFMS) of small independent populations of peripheral nerve motor axons can evoke selective, fatigue-resistant muscle forces. We previously developed a real-time proportional closed-loop control method for aIFMS generation of isometric muscle force and the present work extends and adapts this closed-loop controller to the more demanding task of dynamically controlling joint position in the presence of opposing joint torque. A proportional-integral-velocity controller, with integrator anti-windup strategies, was experimentally validated as a means to evoke motion about the hind-limb ankle joint of an anesthetized feline via aIFMS stimulation of fast-twitch plantar-flexor muscles...
2016: Frontiers in Neuroscience
Kristin Halvorsen Hortemo, Per Kristian Lunde, Jan Haug Anonsen, Heidi Kvaløy, Morten Munkvik, Tommy Aune Rehn, Ivar Sjaastad, Ida Gjervold Lunde, Jan Magnus Aronsen, Ole M Sejersted
Protein O-GlcNAcylation has emerged as an important intracellular signaling system with both physiological and pathophysiological functions, but the role of protein O-GlcNAcylation in skeletal muscle remains elusive. In this study, we tested the hypothesis that protein O-GlcNAcylation is a dynamic signaling system in skeletal muscle in exercise and disease. Immunoblotting showed different protein O-GlcNAcylation pattern in the prototypical slow twitch soleus muscle compared to fast twitch EDL from rats, with greater O-GlcNAcylation level in soleus associated with higher expression of the modulating enzymes O-GlcNAc transferase (OGT), O-GlcNAcase (OGA), and glutamine fructose-6-phosphate amidotransferase isoforms 1 and 2 (GFAT1, GFAT2)...
September 2016: Physiological Reports
Xiaoxi Zhu, Melanie Kny, Franziska Schmidt, Alexander Hahn, Tobias Wollersheim, Christian Kleber, Steffen Weber-Carstens, Jens Fielitz
OBJECTIVE: In sepsis, the disease course of critically ill patients is often complicated by muscle failure leading to ICU-acquired weakness. The myokine transforming growth factor-β1 increases during inflammation and mediates muscle atrophy in vivo. We observed that the transforming growth factor-β1 inhibitor, secreted frizzled-related protein 2, was down-regulated in skeletal muscle of ICU-acquired weakness patients. We hypothesized that secreted frizzled-related protein 2 reduction enhances transforming growth factor-β1-mediated effects and investigated the interrelationship between transforming growth factor-β1 and secreted frizzled-related protein 2 in inflammation-induced atrophy...
September 21, 2016: Critical Care Medicine
Jason C Siegler, Kurt Mudie, Paul Marshall
The effect of metabolic alkalosis on fibre-specific maximal force production and rates of force development (RFD) has been previously investigated in animal models, with evidence suggesting an improved capacity to rapidly develop force in fast- compared to slow-twitch muscle. We have attempted to model in vivo the fatigue profile of voluntary and involuntary maximal force and RFD in the triceps' surae and brachii after sodium bicarbonate (NaHCO3 ) ingestion. In a double-blind, 3-way repeated measures design participants (n = 10) ingested either 0...
September 16, 2016: Experimental Physiology
Thomas Fröhlich, Elisabeth Kemter, Florian Flenkenthaler, Nikolai Klymiuk, Kathrin A Otte, Andreas Blutke, Sabine Krause, Maggie C Walter, Rüdiger Wanke, Eckhard Wolf, Georg J Arnold
Duchenne muscular dystrophy (DMD) is caused by genetic deficiency of dystrophin and characterized by massive structural and functional changes of skeletal muscle tissue, leading to terminal muscle failure. We recently generated a novel genetically engineered pig model reflecting pathological hallmarks of human DMD better than the widely used mdx mouse. To get insight into the hierarchy of molecular derangements during DMD progression, we performed a proteome analysis of biceps femoris muscle samples from 2-day-old and 3-month-old DMD and wild-type (WT) pigs...
2016: Scientific Reports
Rositsa Raikova, Piotr Krutki, Jan Celichowski
An unfused tetanus of a motor unit (MU) evoked by a train of pulses at variable interpulse intervals is the sum of non-equal twitch-like responses to these stimuli. A tool for a precise prediction of these successive contractions for MUs of different physiological types with different contractile properties is crucial for modeling the whole muscle behavior during various types of activity. The aim of this paper is to develop such a general mathematical algorithm for the MUs of the medial gastrocnemius muscle of rats...
2016: PloS One
Hidemi Misawa, Daijiro Inomata, Miseri Kikuchi, Sae Maruyama, Yasuhiro Moriwaki, Takashi Okuda, Nobuyuki Nukina, Tomoyuki Yamanaka
VAChT-Cre.Fast and VAChT-Cre.Slow mice selectively express Cre recombinase in approximately one half of post-natal somatic motor neurons. The mouse lines have been used in various studies with selective genetic modifications in adult motor neurons. In the present study, we crossed VAChT-Cre lines with a reporter line, CAG-Syp/tdTomato, in which synaptophysin-tdTomato fusion proteins are efficiently sorted to axon terminals, making it possible to label both cell bodies and axon terminals of motor neurons. In the mice, Syp/tdTomato fluorescence preferentially co-localized with osteopontin, a recently discovered motor neuron marker for slow-twitch fatigue-resistant (S) and fast-twitch fatigue-resistant (FR) types...
September 6, 2016: Genesis: the Journal of Genetics and Development
Janet D Talbot, John N Barrett, Doris Nonner, Zhongsheng Zhang, Kyle Wicomb, Ellen F Barrett
In mutant superoxide dismutase 1 (SOD1) mouse models of familial amyotrophic lateral sclerosis (fALS) some of the earliest signs of morphological and functional damage occur in the motor nerve terminals that innervate fast limb muscles. This study tested whether localized peripheral application of a protective drug could effectively preserve neuromuscular junctions in late-stage disease. Methylene blue (MB), which has mitochondria-protective properties, was infused via an osmotic pump into the anterior muscle compartment of one hind limb of late pre- symptomatic SOD1-G93A mice for ≥3weeks...
November 2016: Experimental Neurology
Benjamin P Woodall, Meryl C Woodall, Timothy S Luongo, Laurel A Grisanti, Douglas G Tilley, John W Elrod, Walter J Koch
GRK2, a G protein-coupled receptor kinase, plays a critical role in cardiac physiology. Adrenergic receptors are the primary target for GRK2 activity in the heart; phosphorylation by GRK2 leads to desensitization of these receptors. As such, levels of GRK2 activity in the heart directly correlate with cardiac contractile function. Furthermore, increased expression of GRK2 after cardiac insult exacerbates injury and speeds progression to heart failure. Despite the importance of this kinase in both the physiology and pathophysiology of the heart, relatively little is known about the role of GRK2 in skeletal muscle function and disease...
October 14, 2016: Journal of Biological Chemistry
Anna Salazar-Degracia, David Blanco, Mònica Vilà-Ubach, Gabriel de Biurrun, Carlos Ortiz de Solórzano, Luis M Montuenga, Esther Barreiro
BACKGROUND: Muscle wasting negatively impacts the progress of chronic diseases such as lung cancer (LC) and emphysema, which are in turn interrelated. OBJECTIVES: We hypothesized that muscle atrophy and body weight loss may develop in an experimental mouse model of lung carcinogenesis, that the profile of alterations in muscle fiber phenotype (fiber type composition and morphometry, muscle structural alterations, and nuclear apoptosis), and in muscle metabolism are similar in both respiratory and limb muscles of the tumor-bearing mice, and that the presence of underlying emphysema may influence those events...
2016: Journal of Translational Medicine
Sébastien S Dufresne, Antoine Boulanger-Piette, Sabrina Bossé, Jérôme Frenette
The bone remodeling and homeostasis are mainly controlled by the receptor-activator of nuclear factor kB (RANK), its ligand RANKL, and the soluble decoy receptor osteoprotegerin (OPG) pathway. While there is a strong association between osteoporosis and skeletal muscle dysfunction, the functional relevance of a particular biological pathway that synchronously regulates bone and skeletal muscle physiopathology remains elusive. Our recent article published in the American Journal of Physiology (Cell Physiology) showed that RANK is also expressed in fully differentiated C2C12 myotubes and skeletal muscles...
May 30, 2016: Receptors & Clinical Investigation
Dawid Łochyński, Dominik Kaczmarek, Włodzimierz Mrówczyński, Wojciech Warchoł, Joanna Majerczak, Janusz Karasiński, Michał Korostyński, Jerzy A Zoladz, Jan Celichowski
Dynamic resistance training increases the force and speed of muscle contraction, but little is known about modifications to the contractile properties of the main physiological types of motor units (MUs) that contribute to these muscle adaptations. Although the contractile profile of MU muscle fibers is tightly coupled to myosin heavy chain (MyHC) protein expression, it is not well understood if MyHC transition is a prerequisite for modifications to the contractile characteristics of MUs. In this study, we examined MU contractile properties, the mRNA expression of MyHC, parvalbumin, and sarcoendoplasmic reticulum Ca(2+) pump isoforms, as well as the MyHC protein content after 5 wk of volitional progressive weight-lifting training in the medial gastrocnemius muscle in rats...
October 1, 2016: Journal of Applied Physiology
Justin E Sperringer, Robert W Grange
In vitro muscle contractile function assays are important to characterize the differences between different muscle types (e.g., slow vs. fast), between a diseased and non-diseased muscle, or importantly, to demonstrate the efficacy of a muscle treatment such as a drug, an overexpressed transgene, or knockout of a specific gene. Fundamental contractile properties can be assessed by twitch, tetanic, force-frequency, force-velocity, and fatigue assays. Many of these assays are conducted with the muscle at a constant length, e...
2016: Methods in Molecular Biology
Xuan Liu, Nares Trakooljul, Frieder Hadlich, Eduard Muráni, Klaus Wimmers, Siriluck Ponsuksili
BACKGROUND: MicroRNAs (miRNAs) are small non-coding RNAs that play critical roles in diverse biological processes via regulation of gene expression including in skeletal muscles. In the current study, miRNA expression profile was investigated in longissimus muscle biopsies of malignant hyperthermia syndrome-negative Duroc and Pietrain pigs with distinct muscle metabolic properties in order to explore the regulatory role of miRNAs related to mitochondrial respiratory activity and metabolic enzyme activity in skeletal muscle...
2016: BMC Genomics
Andrew J Murton, Matthew Maddocks, Francis B Stephens, Kanagaraj Marimuthu, Ruth England, Andrew Wilcock
INTRODUCTION: The loss of muscle is common in patients with advanced non-small-cell lung cancer (NSCLC) and contributes to the high morbidity and mortality of this group. The exact mechanisms behind the muscle loss are unclear. PATIENTS AND METHODS: To investigate this, 4 patients with stage IV NSCLC who met the clinical definitions for sarcopenia and cachexia were recruited, along with 4 age-matched healthy volunteers. After an overnight fast, biopsy specimens were obtained from the vastus lateralis, and the key components associated with inflammation and the control of muscle protein, carbohydrate, and fat metabolism were assessed...
June 25, 2016: Clinical Lung Cancer
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