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https://www.readbyqxmd.com/read/27896430/myosin-light-chain-phosphorylation-is-required-for-peak-power-output-of-mouse-fast-skeletal-muscle-in-vitro
#1
Joshua Bowslaugh, William Gittings, Rene Vandenboom
The skeletal myosin light chain kinase (skMLCK) catalyzed phosphorylation of the myosin regulatory light chain (RLC) is associated with potentiation of force, work, and power in rodent fast twitch muscle. The purpose of this study was to compare concentric responses of EDL from wild-type (WT) and skMLCK devoid (skMLCK(-/-)) muscles at a range of shortening speeds (0.05 to 0.70 V max) around that expected to produce maximal power (in vitro, 25 °C) both before (unpotentiated) and after (potentiated) a potentiating stimulus (PS)...
November 28, 2016: Pflügers Archiv: European Journal of Physiology
https://www.readbyqxmd.com/read/27895593/baseline-muscle-mass-is-a-poor-predictor-of-functional-overload-induced-gain-in-the-mouse-model
#2
Audrius Kilikevicius, Lutz Bunger, Arimantas Lionikas
Genetic background contributes substantially to individual variability in muscle mass. Muscle hypertrophy in response to resistance training can also vary extensively. However, it is less clear if muscle mass at baseline is predictive of the hypertrophic response. The aim of this study was to examine the effect of genetic background on variability in muscle mass at baseline and in the adaptive response of the mouse fast- and slow-twitch muscles to overload. Males of eight laboratory mouse strains: C57BL/6J (B6, n = 17), BALB/cByJ (n = 7), DBA/2J (D2, n = 12), B6...
2016: Frontiers in Physiology
https://www.readbyqxmd.com/read/27891608/compensatory-axon-sprouting-for-very-slow-axonal-die-back-in-a-transgenic-model-of-spinal-muscular-atrophy-type-iii
#3
Esther Udina, Charles Putman, Luke Harris, N Tyreman, Victoria Cook, Tessa Gordon
Spinal muscular atrophy (SMA) is a common autosomal recessive disorder in humans and is the leading genetic cause of infantile death. Patients lack the SMN1 gene with the severity of the disease depending on the number of copies of the highly homologous SMN2 gene. Although motoneuron death in the Smn+/- transgenic mouse model of mildest form of SMA, SMA type III, has been reported, we have used retrograde tracing of sciatic and femoral motoneurons in the hindlimb with recording of muscle and motor unit isometric forces to count the number of motoneurons with intact neuromuscular connections...
November 28, 2016: Journal of Physiology
https://www.readbyqxmd.com/read/27891518/size-and-proportions-of-slow-twitch-and-fast-twitch-muscle-fibers-in-human-costal-diaphragm
#4
Marija Meznaric, Erika Cvetko
Smaller diaphragmatic motor unit potentials (MUPs) compared to MUPs of limb muscles lead to the hypothesis that diaphragmatic muscle fibers, being the generators of MUPs, might be also smaller. We compared autopsy samples of costal diaphragm and vastus lateralis of healthy men with respect to fibers' size and expression of slow myosin heavy chain isoform (MyHC-1) and fast 2A isoform (MyHC-2A). Diaphragmatic fibers were smaller than fibers in vastus lateralis with regard to the mean minimal fiber diameter of slow-twitch (46...
2016: BioMed Research International
https://www.readbyqxmd.com/read/27884960/can-inorganic-phosphate-explain-sag-during-unfused-tetanic-contractions-of-skeletal-muscle
#5
Ian C Smith, Catherine Bellissimo, Walter Herzog, A Russell Tupling
We test the hypothesis that cytosolic inorganic phosphate (Pi) can account for the contraction-induced reductions in twitch duration which impair summation and cause force to decline (sag) during unfused tetanic contractions of fast-twitch muscle. A five-state model of crossbridge cycling was used to simulate twitch and unfused tetanic contractions. As Pi concentration ([Pi]) was increased from 0 to 30 mmol·L(-1), twitch duration decreased, with progressive reductions in sensitivity to Pi as [Pi] was increased...
November 2016: Physiological Reports
https://www.readbyqxmd.com/read/27882537/neurochemical-and-behavioral-effects-of-hypidone-hydrochloride-yl-0919-a-novel-combined-selective-serotonin-reuptake-inhibitor-and-partial-5-ht1a-agonist
#6
Li-Ming Zhang, Xiao-Yun Wang, Nan Zhao, Yu-Lu Wang, Xiao-Xu Hu, Yu-Hua Ran, Yan-Qin Liu, You-Zhi Zhang, Ri-Fang Yang, Yun-Feng Li
The purpose of the present study was to investigate the pharmacology of hypidone hydrochloride (YL-0919), a novel selective serotonin reuptake inhibitor (SSRI) and 5-hydroxytryptamine (5-HT)1A receptor agonist with high affinity for serotonin transporter (SERT) and 5-HT1A receptors. YL-0919 promoted [(35) S]GTPγ S binding at 85% of the magnitude of the full 5-HT1A receptor agonist 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT), suggesting that YL-0919 is a high-efficacy partial agonist of 5-HT1A receptors...
November 24, 2016: British Journal of Pharmacology
https://www.readbyqxmd.com/read/27879346/the-zebrafish-frozen-mutant-is-a-model-for-human-myopathy-associated-with-mutation-of-the-unconventional-myosin-myo18b
#7
Ritika Gurung, Yosuke Ono, Sarah Baxendale, Samantha Lin Chiou Lee, Steven Moore, Meredith Calvert, Philip W Ingham
MYOSIN 18B is an unconventional myosin that has been implicated in tumour progression in humans. In addition, loss-of-function mutations of the MYO18B gene have recently been identified in several patients exhibiting symptoms of nemaline myopathy. In mouse, mutation of Myo18B results in early developmental arrest associated with cardiomyopathy, precluding analysis of its effects on skeletal muscle development. The zebrafish, frozen (fro) mutant was identified as one of a group of immotile mutants in the 1996 Tübingen genetic screen...
November 22, 2016: Genetics
https://www.readbyqxmd.com/read/27869526/pgc-1%C3%AE-over-expression-suppresses-the-skeletal-muscle-atrophy-and-myofiber-type-composition-during-hindlimb-unloading
#8
Jing Wang, Fei Wang, Peng Zhang, Hongju Liu, Jian He, Chenyu Zhang, Ming Fan, Xiaoping Chen
Disuse leads to severe muscle atrophy and a slow-to-fast myofiber-type transition. PGC-1α (Peroxisome proliferator-activated receptor γ coactivator 1α) is documented to play an important role in muscle atrophy and slow-twitch myofiber determination. Transcription of atrophy-related Atrogin-1 by FoxO3 can be reduced by PGC-1α. While Smad3 augments FoxO3-induced Atrogin-1 and MuRF1 promoter activity. So PGC-1α, as a transcription co-activator, may regulate hindlimb unloading (HU)-induced myofiber-type transition and muscle atrophy through Smad3...
November 21, 2016: Bioscience, Biotechnology, and Biochemistry
https://www.readbyqxmd.com/read/27862560/noninvasive-assessment-of-age-gender-and-exercise-effects-on-skeletal-muscle-initial-experience-with-t1-%C3%AF-mri-of-calf-muscle
#9
Xin-Gui Peng, Yuancheng Wang, Shijun Zhang, Yingying Bai, Hui Mao, Gao-Jun Teng, Shenghong Ju
PURPOSE: To prospectively investigate age- and gender-related changes in the fast-twitch (tibialis anterior, TA) and slow-twitch (soleus, SOL) skeletal muscle of healthy rats and volunteers and to compare the exercise-related difference in health volunteers with T1 ρ magnetic resonance imaging (MRI). MATERIALS AND METHODS: In all, 18 rats and 70 humans were involved in this study. For the animal study, T1 ρ relaxation times were measured in the TA and SOL rat muscle with a 3...
November 9, 2016: Journal of Magnetic Resonance Imaging: JMRI
https://www.readbyqxmd.com/read/27861863/exploring-the-role-of-pgc-1%C3%AE-in-defining-nuclear-organisation-in-skeletal-muscle-fibres
#10
Jacob A Ross, Adam Pearson, Yotam Levy, Bettina Cardel, Christoph Handschin, Julien Ochala
Muscle fibres are multinucleated cells, with each nucleus controlling the protein synthesis in a finite volume of cytoplasm termed the myonuclear domain (MND). What determines MND size remains unclear. In the present study, we aimed to test the hypothesis that the level of expression of the transcriptional coactivator PGC-1α and subsequent activation of the mitochondrial biogenesis are major contributors. Hence, we used two transgenic mouse models with varying expression of PGC-1α in skeletal muscles. We isolated myofibres from the fast twitch extensor digitorum longus (EDL) and slow twitch diaphragm muscles...
November 7, 2016: Journal of Cellular Physiology
https://www.readbyqxmd.com/read/27820862/fast-to-slow-transition-of-skeletal-muscle-contractile-function-and-corresponding-changes-in-myosin-heavy-and-light-chain-formation-in-the-r6-2-mouse-model-of-huntington-s-disease
#11
Tanja Hering, Peter Braubach, G Bernhard Landwehrmeyer, Katrin S Lindenberg, Werner Melzer
Huntington´s disease (HD) is a hereditary neurodegenerative disease resulting from an expanded polyglutamine sequence (poly-Q) in the protein huntingtin (HTT). Various studies report atrophy and metabolic pathology of skeletal muscle in HD and suggest as part of the process a fast-to-slow fiber type transition that may be caused by the pathological changes in central motor control or/and by mutant HTT in the muscle tissue itself. To investigate muscle pathology in HD, we used R6/2 mice, a common animal model for a rapidly progressing variant of the disease expressing exon 1 of the mutant human gene...
2016: PloS One
https://www.readbyqxmd.com/read/27799519/piperine-s-mitigation-of-obesity-and-diabetes-can-be-explained-by-its-up-regulation-of-the-metabolic-rate-of-resting-muscle
#12
Leonardo Nogara, Nariman Naber, Edward Pate, Marcella Canton, Carlo Reggiani, Roger Cooke
We identify a target for treating obesity and type 2 diabetes, the consumption of calories by an increase in the metabolic rate of resting skeletal muscle. The metabolic rate of skeletal muscle can be increased by shifting myosin heads from the super-relaxed state (SRX), with a low ATPase activity, to a disordered relaxed state (DRX), with a higher ATPase activity. The shift of myosin heads was detected by a change in fluorescent intensity of a probe attached to the myosin regulatory light chain in skinned skeletal fibers, allowing us to perform a high-throughput screen of 2,128 compounds...
November 15, 2016: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/27793139/a-short-term-statin-treatment-changes-the-contractile-properties-of-fast-twitch-skeletal-muscles
#13
Antoine Boulanger Piette, Sébastien S Dufresne, Jérôme Frenette
BACKGROUND: Cumulative evidence indicates that statins induce myotoxicity. However, the lack of understanding of how statins affect skeletal muscles at the structural, functional, and physiological levels hampers proper healthcare management. The purpose of the present study was to investigate the early after-effects of lovastatin on the slow-twitch soleus (Sol) and fast-twitch extensor digitorum longus (EDL) muscles. METHODS: Adult C57BL/6 mice were orally administrated with placebo or lovastatin [50 mg/kg/d] for 28 days...
October 28, 2016: BMC Musculoskeletal Disorders
https://www.readbyqxmd.com/read/27793012/foxo1-a-novel-insight-into-its-molecular-mechanisms-in-the-regulation-of-skeletal-muscle-differentiation-and-fiber-type-specification
#14
REVIEW
Meng Xu, Xiaoling Chen, Daiwen Chen, Bing Yu, Zhiqing Huang
FoxO1, a member of the forkhead transcription factor forkhead box protein O (FoxO) family, is predominantly expressed in most muscle types. FoxO1 is a key regulator of muscle growth, metabolism, cell proliferation and differentiation. In the past two decades, many researches have indicated that FoxO1 is a negative regulator of skeletal muscle differentiation while contrasting opinions consider that FoxO1 is crucial for myoblast fusion. FoxO1 is expressed much higher in fast twitch fiber enriched muscles than in slow muscles and is also closely related to muscle fiber type specification...
October 25, 2016: Oncotarget
https://www.readbyqxmd.com/read/27792730/time-course-of-muscle-mass-loss-damage-and-proteolysis-in-gastrocnemius-following-unloading-and-reloading-implications-in-chronic-diseases
#15
Alba Chacon-Cabrera, Helena Lund-Palau, Joaquim Gea, Esther Barreiro
BACKGROUND: Disuse muscle atrophy is a major comorbidity in patients with chronic diseases including cancer. We sought to explore the kinetics of molecular mechanisms shown to be involved in muscle mass loss throughout time in a mouse model of disuse muscle atrophy and recovery following immobilization. METHODS: Body and muscle weights, grip strength, muscle phenotype (fiber type composition and morphometry and muscle structural alterations), proteolysis, contractile proteins, systemic troponin I, and mitochondrial content were assessed in gastrocnemius of mice exposed to periods (1, 2, 3, 7, 15 and 30 days) of non-invasive hindlimb immobilization (plastic splint, I cohorts) and in those exposed to reloading for different time-points (1, 3, 7, 15, and 30 days, R cohorts) following a seven-day period of immobilization...
2016: PloS One
https://www.readbyqxmd.com/read/27739112/the-functional-significance-of-hamstrings-composition-is-it-really-a-fast-muscle-group
#16
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
https://www.readbyqxmd.com/read/27736981/impact-of-tieg1-deletion-on-the-passive-mechanical-properties-of-fast-and-slow-twitch-skeletal-muscles-in-female-mice
#17
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
https://www.readbyqxmd.com/read/27736732/conjugated-linoleic-acid-cla-promotes-endurance-capacity-via-peroxisome-proliferator-activated-receptor-%C3%AE-mediated-mechanism-in-mice
#18
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
https://www.readbyqxmd.com/read/27714819/short-and-long-term-hindlimb-immobilization-and-reloading-profile-of-epigenetic-events-in-gastrocnemius
#19
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
https://www.readbyqxmd.com/read/27708586/modeling-ca-2-bound-troponin-in-excitation-contraction-coupling
#20
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
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