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https://www.readbyqxmd.com/read/29347676/twitching-motility-of-bacteria-with-type-iv-pili-fractal-walks-first-passage-time-and-their-consequences-on-microcolonies
#1
Konark Bisht, Stefan Klumpp, Varsha Banerjee, Rahul Marathe
A human pathogen, Neisseria gonorrhoeae (NG), moves on surfaces by attaching and retracting polymeric structures called Type IV pili. The tug-of-war between the pili results in a two-dimensional stochastic motion called twitching motility. In this paper, with the help of real-time NG trajectories, we develop coarse-grained models for their description. The fractal properties of these trajectories are determined and their influence on first passage time and formation of bacterial microcolonies is studied. Our main observations are as follows: (i) NG performs a fast ballistic walk on small time scales and a slow diffusive walk over long time scales with a long crossover region; (ii) there exists a characteristic persistent length l_{p}^{*}, which yields the fastest growth of bacterial aggregates or biofilms...
November 2017: Physical Review. E
https://www.readbyqxmd.com/read/29342086/copy-number-variation-in-sox6-contributes-to-chicken-muscle-development
#2
Shudai Lin, Xiran Lin, Zihao Zhang, Mingya Jiang, Yousheng Rao, Qinghua Nie, Xiquan Zhang
Copy number variations (CNVs), which cover many functional genes, are associated with complex diseases, phenotypic diversity and traits that are economically important to raising chickens. The sex-determining region Y-box 6 (Sox6) plays a key role in fast-twitch muscle fiber differentiation of zebrafish and mice, but it is still unknown whether SOX6 plays a role in chicken skeletal muscle development. We identified two copy number polymorphisms (CNPs) which were significantly related to different traits on the genome level in chickens by AccuCopy® and CNVplex® analyses...
January 17, 2018: Genes
https://www.readbyqxmd.com/read/29335929/computational-model-to-investigate-the-relative-contributions-of-different-neuromuscular-properties-of-tibialis-anterior-on-force-generated-during-ankle-dorsiflexion
#3
Ariba Siddiqi, Sridhar Poosapadi Arjunan, Dinesh Kant Kumar
This study describes a new model of the force generated by tibialis anterior muscle with three new features: single-fiber action potential, twitch force, and pennation angle. This model was used to investigate the relative effects and interaction of ten age-associated neuromuscular parameters. Regression analysis (significance level of 0.05) between the neuromuscular properties and corresponding simulated force produced at the footplate was performed. Standardized slope coefficients were computed to rank the effect of the parameters...
January 16, 2018: Medical & Biological Engineering & Computing
https://www.readbyqxmd.com/read/29315934/effect-of-euk-134-on-akt-mtor-signaling-in-the-rat-soleus-during-7-days-of-mechanical-unloading
#4
J Matthew Kuczmarski, Jeff M Hord, Yang Lee, Vinicius Guzzoni, Dinah Rodriguez, Matthew S Lawler, Erika L Garcia-Villatoro, Dylan Holly, Patrick Ryan, Kristian Falcon, Marcela Garcia, Mariana Janini Gomes, James D Fluckey, John M Lawler
Mechanical unloading stimulates rapid changes in skeletal muscle morphology, characterized by atrophy of muscle fiber cross-sectional area (CSA) and a partial fiber-type shift from slow to fast-twitch. Recent studies revealed that oxidative stress contributes to activation of FoxO3a, proteolytic signaling and unloading-induced muscle atrophy via translocation of the mu-splice variant of neuronal nitric oxide synthase (nNOSμ) and activation of FoxO3a. Yet, there is limited understanding of the role of reactive oxygen species (ROS) on the Akt-mTOR pathway signaling during unloading...
January 8, 2018: Experimental Physiology
https://www.readbyqxmd.com/read/29315676/aging-impairs-regulation-of-ryanodine-receptors-from-edl-but-not-soleus-muscles
#5
Angela J Gaboardi, Jochen Kressler, Teresa K Snow, Edward M Balog
INTRODUCTION: Because impaired excitation-contraction coupling and reduced sarcoplasmic reticulum Ca2+ release may contribute to the age-associated decline in skeletal muscle strength, we investigated the effect of aging on RyR1 regulation by physiological channel ligands. METHODS: [3 H]Ryanodine binding to membranes from 8 and 26 month old Fischer 344 extensor digitorum longus (EDL) and soleus muscles was used to investigate the effects of age on RyR1 modulation by Ca2+ and calmodulin (CaM)...
January 9, 2018: Muscle & Nerve
https://www.readbyqxmd.com/read/29299218/electrical-stimulation-frequency-and-skeletal-muscle-characteristics-effects-on-force-and-fatigue
#6
Maria Vromans, Pouran Faghri
This investigation aimed to determine the force and muscle surface electromyography (EMG) responses to different frequencies of electrical stimulation (ES) in two groups of muscles with different size and fiber composition (fast- and slow-twitch fiber proportions) during a fatigue-inducing protocol. Progression towards fatigue was evaluated in the abductor pollicis brevis (APB) and vastus lateralis (VL) when activated by ES at three frequencies (10, 35, and 50Hz). Ten healthy adults (mean age: 23.2 ± 3.0 years) were recruited; participants signed an IRB approved consent form prior to participation...
December 5, 2017: European Journal of Translational Myology
https://www.readbyqxmd.com/read/29298217/sex-differences-in-mechanisms-of-recovery-after-isometric-and-dynamic-fatiguing-tasks
#7
Jonathon Senefeld, Hugo M Pereira, Nicholas Elliott, Tejin Yoon, Sandra K Hunter
PURPOSE: Determine whether supraspinal mechanisms contribute to the sex difference in fatigability during and recovery from a dynamic and isometric fatiguing task with the knee extensors. METHODS: Transcranial magnetic stimulation (TMS) and electrical stimulation were used to determine voluntary activation and contractile properties of the knee extensors in 14 men and 17 women (20.8±1.9 years) after a: 1) 60-s sustained, maximal voluntary isometric contraction (MVIC), and 2) dynamic fatiguing task involving 120 maximal voluntary concentric contractions with a 20% MVIC load...
January 3, 2018: Medicine and Science in Sports and Exercise
https://www.readbyqxmd.com/read/29291007/alteration-of-muscle-fiber-characteristics-and-the-ampk-sirt1-pgc-1%C3%AE-axis-in-skeletal-muscle-of-growing-pigs-fed-low-protein-diets-with-varying-branched-chain-amino-acid-ratios
#8
Yehui Duan, Fengna Li, Wenlong Wang, Qiuping Guo, Chaoyue Wen, Yulong Yin
There mainly exists four major myosin heavy chains (MyHC) (i.e., I, IIa, IIx, and IIb) in growing pigs. The current study aimed to explore the effects of low-protein diets supplemented with varying branched-chain amino acids (BCAAs) on muscle fiber characteristics and the AMPK-SIRT1-PGC-1α axis in skeletal muscles. Forty growing pigs (9.85 ± 0.35 kg) were allotted to 5 groups and fed with diets supplemented with varying leucine: isoleucine: valine ratios: 1:0.51:0.63 (20% crude protein, CP), 1:1:1 (17% CP), 1:0...
December 5, 2017: Oncotarget
https://www.readbyqxmd.com/read/29289708/effect-of-ageing-on-the-myosin-heavy-chain-composition-of-the-human-sternocleidomastoid-muscle
#9
M Meznaric, I Eržen, P Karen, E Cvetko
The myosin heavy chain (MyHC) composition of ageing limb muscles is transformed into a slower phenotype and expresses fast-twitch fiber type atrophy, presumably due to age-related motor unit remodeling and a change in the patterns of physical activity. It is not known if ageing affects the sternocleidomastoid muscle (SCM) in a similar way. The goal of the study was to analyze the MyHC composition and the size of muscle fibres in the ageing SCM by immunohistochemical methods and quantitative analysis and stereology using our own software for morphometry...
December 28, 2017: Annals of Anatomy, Anatomischer Anzeiger: Official Organ of the Anatomische Gesellschaft
https://www.readbyqxmd.com/read/29229646/nhe-and-diffusion-dependent-proton-fluxes-across-the-tubular-system-membranes-of-fast-twitch-muscle-fibers-of-the-rat
#10
Bradley S Launikonis, Tanya R Cully, Laszlo Csernoch, D George Stephenson
The complex membrane structure of the tubular system (t-system) in skeletal muscle fibers is open to the extracellular environment, which prevents measurements of H+ movement across its interface with the cytoplasm by conventional methods. Consequently, little is known about the t-system's role in the regulation of cytoplasmic pH, which is different from extracellular pH. Here we describe a novel approach to measure H+-flux measurements across the t-system of fast-twitch fibers under different conditions. The approach involves loading the t-system of intact rat fast-twitch fibers with a strong pH buffer (20 mM HEPES) and pH-sensitive fluorescent probe (10 mM HPTS) before the t-system is sealed off...
December 11, 2017: Journal of General Physiology
https://www.readbyqxmd.com/read/29225211/changes-in-foxo-and-proinflammatory-cytokines-in-the-late-stage-of-immobilized-fast-and-slow-muscle-atrophy
#11
Takeshi Okamoto, Shuichi Machida
The present study aimed to examine the changes in the expression of Forkhead box protein O (FOXO) and proinflammatory cytokines in both slow-twitch soleus and fast-twitch plantaris muscles following cast immobilization. Male C57BL/6 mice were subjected to cast immobilization for 7 and 21 days. Cast immobilization increased FOXO3a mRNA and total protein expression in both the soleus and plantaris muscles. Although FOXO3a phosphorylation tended to increase in response to cast immobilization in both muscles, a significant increase was evident after 21 days of immobilization only in the soleus muscle...
2017: Biomedical Research
https://www.readbyqxmd.com/read/29206782/muscle-fiber-and-performance-changes-after-fast-eccentric-complex-training
#12
Gregory C Bogdanis, Athanasios Tsoukos, Lee E Brown, Elisavet Selima, Panagiotis Veligekas, Konstantinos Spengos, Gerasimos Terzis
INTRODUCTION: The purpose of this study was to examine the effects of a short-term fast eccentric and ballistic complex training program on muscle power, rate of force development (RFD), muscle fiber composition and cross-sectional area (CSA). METHODS: Sixteen male physical education students were randomly assigned to either a training group (TG, n=8) or a control group (C, n=8). The TG followed a 6-week low volume training program, including fast eccentric squat training with an individually optimized load of 74±7% of maximal half-squat strength (1RM) twice per week and a ballistic training session with loaded (30% 1RM) and unloaded jump squats, once per week, all combined with unloaded plyometric jumps...
December 2, 2017: Medicine and Science in Sports and Exercise
https://www.readbyqxmd.com/read/29186696/a-highly-sensitive-fret-biosensor-for-ampk-exhibits-heterogeneous-ampk-responses-among-cells-and-organs
#13
Yumi Konagaya, Kenta Terai, Yusuke Hirao, Kanako Takakura, Masamichi Imajo, Yuji Kamioka, Norio Sasaoka, Akira Kakizuka, Kenta Sumiyama, Tomoichiro Asano, Michiyuki Matsuda
AMP-activated protein kinase (AMPK), a master regulator of cellular metabolism, is a potential target for type 2 diabetes. Although extensive in vitro studies have revealed the complex regulation of AMPK, much remains unknown about the regulation in vivo. We therefore developed transgenic mice expressing a highly sensitive fluorescence resonance energy transfer (FRET)-based biosensor for AMPK, called AMPKAR-EV. AMPKAR-EV allowed us to readily examine the role of LKB1, a canonical stimulator of AMPK, in drug-induced activation and inactivation of AMPK in vitro...
November 28, 2017: Cell Reports
https://www.readbyqxmd.com/read/29185184/changes-in-contractile-and-metabolic-parameters-of-skeletal-muscle-as-rats-age-from-3-to-12-months
#14
Hongyang Xu, Graham D Lamb, Robyn M Murphy
Laboratory rats are considered mature at 3 months despite that musculoskeletal growth is still occurring. Changes in muscle physiological and biochemical characteristics during development from 3 months, however, are not well understood. Whole muscles and single skinned fibres from fast-twitch extensor digitorum longus (EDL) and predominantly slow-twitch soleus (SOL) muscles were examined from male Sprague-Dawley rats (3, 6, 9, 12 months). Ca2+ sensitivity of contractile apparatus decreased with age in both fast- (~ 0...
November 28, 2017: Journal of Muscle Research and Cell Motility
https://www.readbyqxmd.com/read/29169055/functional-electrical-stimulation-induced-muscular-fatigue-effect-of-fiber-composition-and-stimulation-frequency-on-rate-of-fatigue-development
#15
Maria Vromans, Pouran D Faghri
This investigation evaluated the progression towards fatigue in two muscles of differing fast- and slow-twitch fiber proportions (abductor pollicis brevis (APB) and vastus lateralis (VL)) when activated by functional electrical stimulation (FES) at three frequencies (10, 35, and 50 Hz). Fatigue was defined as a 50% drop from the initial FES-induced force of 25% maximal voluntary contraction (MVC). Ten healthy adults (mean age: 23.2 ± 3.0 years) were recruited; participants signed an IRB approved consent form prior to participation...
November 20, 2017: Journal of Electromyography and Kinesiology
https://www.readbyqxmd.com/read/29168286/comparative-proteomic-profiling-reveals-a-role-for-cisd2-in-skeletal-muscle-aging
#16
Yi-Long Huang, Zhao-Qing Shen, Chia-Yu Wu, Yuan-Chi Teng, Chen-Chung Liao, Cheng-Heng Kao, Liang-Kung Chen, Chao-Hsiung Lin, Ting-Fen Tsai
Skeletal muscle has emerged as one of the most important tissues involved in regulating systemic metabolism. The gastrocnemius is a powerful skeletal muscle composed of predominantly glycolytic fast-twitch fibers that are preferentially lost among old age. This decrease in gastrocnemius muscle mass is remarkable during aging; however, the underlying molecular mechanism is not fully understood. Strikingly, there is a ~70% decrease in Cisd2 protein, a key regulator of lifespan in mice and the disease gene for Wolfram syndrome 2 in humans, within the gastrocnemius after middle age among mice...
November 23, 2017: Aging Cell
https://www.readbyqxmd.com/read/29152896/trimetazidine-restores-the-positive-adaptation-to-exercise-training-by-mitigating-statin-induced-skeletal-muscle-injury
#17
Ming Song, Fang-Fang Chen, Yi-Hui Li, Lei Zhang, Feng Wang, Ran-Ran Qin, Zhi-Hao Wang, Ming Zhong, Meng-Xiong Tang, Wei Zhang, Lu Han
BACKGROUND: Exercise rehabilitation is demonstrated to improve the prognosis of patients with coronary heart disease (CHD). Statins, as the key medicine to lower cholesterol in CHD, result in skeletal muscle injury and impair exercise training adaptation. Energy metabolism dysfunction is identified as the potential mechanism underlying statin-induced skeletal muscle injury. In this study, we investigated the effects of the metabolic modulator trimetazidine on skeletal muscle energy metabolism and statin-associated exercise intolerance...
November 19, 2017: Journal of Cachexia, Sarcopenia and Muscle
https://www.readbyqxmd.com/read/29146687/exercise-induces-muscle-fiber-type-switching-via-transient-receptor-potential-melastatin-2-trpm2-dependent-ca-2-signaling
#18
Seo-Ho Lee, Byung-Ju Kim, Dae-Ryoung Park, Uh-Hyun Kim
The aim of the present study was to examine whether transient receptor potential melastatin 2 (TRPM2) plays a role in muscle fiber type transition during exercise. Mice were trained at a speed of 12 m/min at a slope of 0 ° for 60 min 5 consecutive d/wk for 4-wk. Exhaustion tests were performed on the treadmill (the speed was set at 6 m/min at a slope of 0° and increased at a rate of 1 m/min every 6 min). Isolated primary skeletal muscle cells from TRPM2 knockout (KO) mice showed lower amplitudes of electrical stimuli (ES)-induced Ca(2+) signals when compared to wild-type (WT) mice, due to a defect in Ca(2+) influx...
November 16, 2017: Journal of Applied Physiology
https://www.readbyqxmd.com/read/29120762/intramuscular-variations-of-proteome-and-muscle-fiber-type-distribution-in-semimembranosus-and-semitendinosus-muscles-associated-with-pork-quality
#19
Gap-Don Kim, Han-Sul Yang, Jin-Yeon Jeong
Proteome analysis was performed to understand intramuscular variations in muscle fiber distribution in semimembranosus (SM) and semitendinosus (ST) muscles associated with pork quality. Fifteen SM and ST muscles were separated into dark and light portions. The relative area of oxidative fiber was higher (P < .0001) in dark portion than that in light portion, while glycolytic fiber types were distributed primarily (P < .01) in light portions regardless of muscle types. Myosin-1, myosin-4, troponin complex (fast), myosin light chains, and metabolic enzymes responsible for fast-twitch glycolytic types were overexpressed in light portions (P < ...
April 1, 2018: Food Chemistry
https://www.readbyqxmd.com/read/29119399/green-tea-extract-increases-the-expression-of-genes-responsible-for-regulation-of-calcium-balance-in-rat-slow-twitch-muscles-under-conditions-of-exhausting-exercise
#20
E A Korf, I V Kubasov, M S Vonsky, A V Novozhilov, A L Runov, E V Kurchakova, E V Matrosova, T V Tavrovskaya, N V Goncharov
We studied the role of calcium-regulating structures of slow- (m. soleus, SOL) and fast-twitch (m. extensor digitorum longus, EDL) skeletal muscles of rats during adaptation to exhausting physical activity and the possibility of modulating this adaptation with decaffeinated green tea extract. It was established that EDL adaptation is mainly aimed at Са(2+) elimination from the sarcoplasm by Са-ATPase and its retention in the reticulum by calsequestrin. Administration of green tea extract increased endurance due to involvement of slow-twitch muscles whose adaptation is associated with enhanced expression of all the studied genes responsible for the regulation of Ca(2+) balance...
November 9, 2017: Bulletin of Experimental Biology and Medicine
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