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Muscle force

Angela Trocino, Cristina Zomeño, Marco Birolo, Guido Di Martino, Annalisa Stefani, Lebana Bonfanti, Daniela Bertotto, Francesco Gratta, Gerolamo Xiccato
In growing rabbits (n = 320; 84 d of age), an increase in the journey duration to the slaughterhouse from 1 h to 3 h under mild climatic conditions (10-13 °C; 75-90% relative humidity) affected several stress indicators in the plasma and muscle collected at slaughter (cortisol; corticosterone; lactate dehydrogenase, LDH; lactate; heat shock protein 70 kDa, HSP70; osmolality, and Na) (0.001 < P < .05), reduced muscle L*, b* (P < .01), and meat shear force (P < .05), and increased the dressing out percentage and muscle pH (P < ...
August 1, 2018: Meat Science
David W Russ, Sean M Garvey, Clay Densmore, Trevor Hawks, Stephanie Herman, Katherine Pardi
AIM: Contusion injury in aging muscle has not been studied in detail, but older adults are at risk for such injuries due to increased risk of falls. As falls in older populations are unlikely to be eliminated, interventions to minimize the negative impact of falls, including contusion injury should be pursued. Dietary fish oil (FO) is a common often supplement in older adults, which is associated with factors that might reduce or worsen the negative impact of contusion. METHODS: Here, we investigate whether 8 weeks of FO can blunt the impact of contusion injury in adult (n = 14) and aged (n = 12) rats...
August 10, 2018: Experimental Gerontology
Christopher T Pappas, Gerrie P Farman, Rachel M Mayfield, John P Konhilas, Carol C Gregorio
Leiomodin-2 (Lmod2) is a striated muscle-specific actin binding protein that is implicated in assembly of thin filaments. The necessity of Lmod2 in the adult mouse and role it plays in the mechanics of contraction are unknown. To answer these questions, we generated cardiac-specific conditional Lmod2 knockout mice (cKO). These mice die within a week of induction of the knockout with severe left ventricular systolic dysfunction and little change in cardiac morphology. Cardiac trabeculae isolated from cKO mice have a significant decrease in maximum force production and a blunting of myofilament length-dependent activation...
August 10, 2018: Journal of Molecular and Cellular Cardiology
William A Kronert, Kaylyn M Bell, Meera C Viswanathan, Girish C Melkani, Adriana S Trujillo, Alice Huang, Anju Melkani, Anthony Cammarato, Douglas M Swank, Sanford I Bernstein
K146N is a dominant mutation in human β-cardiac myosin heavy chain, which causes hypertrophic cardiomyopathy. We examined how Drosophila muscle responds to this mutation and integratively analyzed the biochemical, physiological and mechanical foundations of the disease. ATPase assays, actin motility, and indirect flight muscle mechanics suggest at least two rate constants of the cross-bridge cycle are altered by the mutation: increased myosin attachment to actin and decreased detachment, yielding prolonged binding...
August 13, 2018: ELife
Álvaro Bustamante-Sánchez, Miguel Delgado-Terán, Vicente Javier Clemente-Suárez
Hypoxia remains the most important hazard in high altitude flights, but there is still a need for deeper analysis of the effect of hypoxia exposition in the psychophysiological and cognitive functions. The aim of this study was to study the effect of hypoxia training in cortical arousal, autonomic modulation, muscle strength and cognitive function. We analysed 23 male aircrew personnel of the Spanish Army and Air Force (10 Helicopter Pilots, 7 Transport Aircrew, 3 Transport Pilots and 3 F-18 Fighter Pilots) before, during and after a normobaric hypoxia exposition...
August 13, 2018: Ergonomics
Antonis Giannopoulos, Rene B Svensson, Katja M Heinemeier, Peter Schjerling, Karl E Kadler, David F Holmes, Michael Kjaer, S Peter Magnusson
Tendons transmit contractile muscular force to bone to produce movement, and it is believed cells can generate endogenous forces on the extracellular matrix to maintain tissue homeostasis. However, little is known about the direct mechanical measurement of cell-matrix interaction in cell-generated human tendon constructs. In this study we examined if cell-generated force could be detected and quantified in engineered human tendon constructs, and if glycosaminoglycans (GAGs) contribute to tendon force transmission...
July 30, 2018: Journal of Biomechanics
Callum J Donaldson, Ka Hou Lao, Lingfang Zeng
Atherosclerosis, a chronic inflammatory condition that is characterized by the accumulation of lipid-loaded macrophages, occurs preferentially at the arterial branching points where disturbed flow is prominent. The pathogenesis of atherosclerotic lesion formation is a multistage process involving multiple cell types, inflammatory mediators and hemodynamic forces in the vessel wall in response to atherogenic stimuli. Researches from the past decade have uncovered the critical roles of microRNAs (miRNAs) in regulating multiple pathophysiological effects and signaling pathways in endothelial cells (ECs), vascular smooth muscle cells (VSMCs), macrophages and lipid homeostasis, which are key in atherosclerotic lesion formation...
August 8, 2018: Journal of Molecular and Cellular Cardiology
Magdalena Zuk, Malgorzata Syczewska, Celina Pezowicz
The purpose of the current study was to investigate the robustness of dynamic simulation results in the presence of uncertainties resulting from application of a scaled-generic musculoskeletal model instead of a subject-specific model as well as the effect of the choice of simulation method on the obtained muscle forces. The performed sensitivity analysis consisted of the following multibody parameter modifications: maximum isometric muscle forces, number of muscles, the hip joint centre location, segment masses as well as different dynamic simulation methods, namely static optimization with three different criteria and a computed muscle control algorithm (hybrid approach combining forward and inverse dynamics)...
July 23, 2018: Journal of Biomechanical Engineering
Andrew J Chappell, Daniel M Allwood, Rebecca Johns, Samantha Brown, Kiran Sultana, Annie Anand, Trevor Simper
BACKGROUND: Use of supplements to aid performance is common practice amongst recreationally active individuals, including those without a sufficient evidence base. This investigation sought to assess whether acute supplementation with 8 g of citrulline malate (CM) (1.11: 1 ratio) would improve anaerobic performance. METHODS: A randomised double blind placebo control trial was employed, using a counterbalanced design. We recruited recreationally active men and women to take part in an isokinetic chair protocol, based on German Volume Training (GVT) whereby participants attempted to perform 10 sets of 10 repetitions against a force representing 70% of their peak concentric force...
August 10, 2018: Journal of the International Society of Sports Nutrition
Mohd Muddassir, Bharat Manna, Priyanka Singh, Surjeet Singh, Rajesh Kumar, Amit Ghosh, Deepak Sharma
Each cellular protein is surrounded by a biochemical milieu that affects its stability and the associated function. The role of this surrounding milieu in the proteins' mechanical stability remains largely unexplored. Herein, we report an as yet unknown correlation between the size of the surrounding anions and the mechanical stability of a protein. Using single-molecule force spectroscopy of the 27th domain (I27) of human cardiac muscle protein titin, we show that the average unfolding force of the protein decreases with increase in the ionic radii of the surrounding anions in the order Cl- > Br- > NO3- > I- > SO42- ≈ ClO4-, indicating an inverse correlation between anion size and the mechanical stability of I27...
August 10, 2018: Chemical Communications: Chem Comm
Tyler M Farney, Michael J MacLellan, Christopher M Hearon, Neil M Johannsen, Arnold G Nelson
Farney, TM, MacLellan, MJ, Hearon, CM, Johannsen, NM, and Nelson, AG. The effect of aspartate and sodium bicarbonate supplementation on muscle contractile properties among trained men. J Strength Cond Res XX(X): 000-000, 2018-The focus of this investigation was to examine the effects of aspartate and NaHCO3 supplementation on muscle contractile properties within trained men. Eleven men (21.9 ± 1.5 years) ingested supplementation as 4 conditions all separated by 1 week and included the following: placebo (PLA), L-aspartate (12...
August 8, 2018: Journal of Strength and Conditioning Research
Thomas Dos'Santos, Christopher Thomas, Paul Comfort, Paul A Jones
Changes of direction (CODs) are key manoeuvres linked to decisive moments in sport and are also key actions associated with lower limb injuries. During sport athletes perform a diverse range of CODs, from various approach velocities and angles, thus the ability to change direction safely and quickly is of great interest. To our knowledge, a comprehensive review examining the influence of angle and velocity on change of direction (COD) biomechanics does not exist. Findings of previous research indicate the biomechanical demands of CODs are 'angle' and 'velocity' dependent and are both critical factors that affect the technical execution of directional changes, deceleration and reacceleration requirements, knee joint loading, and lower limb muscle activity...
August 9, 2018: Sports Medicine
Anne-Violette Bruyneel, Simone C Gafner, Serge Ferrari, Gabriel Gold, Dominique Monnin, Philippe Terrier, Caroline H Bastiaenen, Lara Allet
Background: Reduced hip muscle strength has been shown to be a major factor related to falls in older persons. However, comprehensive assessment of hip abduction strength in the clinical setting is challenging. The aim of this study was to investigate the feasibility and intra-rater reliability of a quick and simple hip abductor strength test in a functional standing position. Methods: Individuals over 65 years of age were recruited from the geriatric department of a university hospital and an outpatient clinic...
2018: European Review of Aging and Physical Activity
Dongsheng Duan
Duchenne muscular dystrophy (DMD) is a lethal muscle disease caused by dystrophin gene mutation. Conceptually, replacing the mutated gene with a normal one would cure the disease. However, this task has encountered significant challenges due to the enormous size of the gene and the distribution of muscle throughout the body. The former creates a hurdle for viral vector packaging and the latter begs for whole-body therapy. To address these obstacles, investigators have invented the highly abbreviated micro-dystrophin gene and developed body-wide systemic gene transfer with adeno-associated virus (AAV)...
July 17, 2018: Molecular Therapy: the Journal of the American Society of Gene Therapy
Mette Flindt Heisterberg, Jesper Løvind Andersen, Peter Schjerling, Alberte Lund, Simone Dalskov, Anders Overgård Jønsson, Nichlas Warming, Mathilde Fogelstrøm, Michael Kjaer, Abigail Louise Mackey
PURPOSE: To investigate the potential of blocking the angiotensin II type I receptor (AT1R) on the hypertrophy response of elderly human skeletal muscle to four months of heavy resistance exercise training. METHODS: 58 healthy elderly men (+65 years) were randomized into three groups, consuming either AT1R blocker (losartan, 100mg/day) or placebo for 4 months. Two groups performed resistance training (RT) and were treated with either losartan or placebo and one group did not train but was treated with losartan...
August 9, 2018: Journal of Applied Physiology
Jia-Zi Dong, Yun-Tao Wei, Huan-Yu Xu, Yu Zhang, Ru-Lin Yong, Ya-Nan Xue, Li-de Zhang
OBJECTIVE: To observe the effect of electroacupuncture (EA) of "Zusanli" (ST 36) on mitochondrial oxidative stress of skeletal muscle in rats with chronic fatigue syndrome (CFS) based on adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK)/ peroxlsome proliferator-activated receptor-γ coactivator-1 α (PGC-1 α) signaling, in order to reveal its mechanism underlying improvement of CFS. METHODS: Forty SD rats were randomly divided into normal control, CFS model, EA-Zusanli (ST 36) and EA-non-acupoint groups ( n =10 rats in each group)...
June 25, 2018: Zhen Ci Yan Jiu, Acupuncture Research
Lei Qi, Tomasz Kolodziej, Zenon Rajfur, Cai Huang
There are two vertebrate talin genes, TLN1 and TLN2, which encode talin1 and talin2. Talin1 governs integrin activation, thus regulating focal adhesion (FA) assembly, cell migration and invasion, but the biological function of talin2 remains to be elucidated and not too long ago talin2 was presumed to function redundantly with talin1. Recent studies have shown distinct differences between talin2 and talin1. The promoter of TLN2 is different from that of TLN1 in their size and binding to different transcription factors...
August 8, 2018: Current Protein & Peptide Science
Gijs Ijpma, Liang Chu Qiao, Linda Kachmar, Alice Panariti, Andrea Benedetti, Jean-Pierre Lavoie, Anne-Marie Lauzon
RATIONALE: Isolated human airway smooth muscle (ASM) tissue contractility studies are essential for understanding the role of ASM in respiratory disease, but limited availability and cost render storage options necessary for optimal use. However, to date no comprehensive study of cryopreservation protocols for isolated ASM has been performed. METHODS: We tested several cryostorage protocols on equine trachealis ASM, using different cryostorage media (1.8M dimethyl sulfoxide and fetal bovine serum [FBS] or Krebs-Henseleit [KH]) and different degrees of dissection (with or without epithelium and connective tissues attached) prior to storage...
August 9, 2018: American Journal of Physiology. Lung Cellular and Molecular Physiology
Arnaud Diffo Kaze, Stefan Maas, Slawomir Kedziora, James Belsey, Alexander Haupert, Claude Wolf, Alexander Hoffmann, Dietrich Pape
BACKGROUND: Many different fixation devices are used to maintain the correction angle after medial open wedge high tibial osteotomy (MOWHTO). Each device must provide at least sufficient mechanical stability to avoid loss of correction and unwanted fracture of the contralateral cortex until the bone heals. In the present study, the mechanical stability of following different implants was compared: the TomoFix small stature (sm), the TomoFix standard (std), the Contour Lock, the iBalance and the second generation PEEKPower...
August 8, 2018: Journal of Experimental Orthopaedics
Chiara Zoppirolli, Lorenzo Bortolan, Federico Stella, Gennaro Boccia, Hans-Christer Holmberg, Federico Schena, Barbara Pellegrini
Introduction: Although short-term (approximately 10-min) fatiguing DP has been reported not to alter the joint kinematics or displacement of the centre of mass (COM) of high-level skiers, we hypothesize that prolonged DP does change these kinematics, since muscular strength is impaired following endurance events lasting longer than 2 h. Methods: During the 58-km Marcialonga race in 2017, the fastest 15 male skiers were videofilmed (100 fps, FHD resolution in the sagittal plane) on two 20-m sections (inclines: 0...
2018: Frontiers in Physiology
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