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https://www.readbyqxmd.com/read/28433388/magnetic-resonance-and-diffusion-tensor-imaging-analyses-indicate-heterogeneous-strains-along-human-medial-gastrocnemius-fascicles-caused-by-submaximal-plantar-flexion-activity
#1
Agah Karakuzu, Uluç Pamuk, Cengizhan Ozturk, Burak Acar, Can A Yucesoy
Sarcomere length changes are central to force production and excursion of skeletal muscle. Previous modeling indicates non-uniformity of that if mechanical interaction of muscle with its surrounding muscular and connective tissues is taken into account. Hence, quantifying length changes along the fascicles of activated human muscle in vivo is crucial, but this is lacking due to technical complexities. Combining magnetic resonance imaging deformation analyses and diffusion tensor imaging tractography, the aim was to test the hypothesis that submaximal plantar flexion activity at 15% MVC causes heterogeneous length changes along the fascicles of human medial gastrocnemius (GM) muscle...
April 9, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28432448/resistance-to-radial-expansion-limits-muscle-strain-and-work
#2
E Azizi, A R Deslauriers, N C Holt, C E Eaton
The collagenous extracellular matrix (ECM) of skeletal muscle functions to transmit force, protect sensitive structures, and generate passive tension to resist stretch. The mechanical properties of the ECM change with age, atrophy, and neuromuscular pathologies, resulting in an increase in the relative amount of collagen and an increase in stiffness. Although numerous studies have focused on the effect of muscle fibrosis on passive muscle stiffness, few have examined how these structural changes may compromise contractile performance...
April 21, 2017: Biomechanics and Modeling in Mechanobiology
https://www.readbyqxmd.com/read/28432254/tlr4-defective-c3h-hej-mice-are-not-protected-from-cast-immobilization-induced-muscle-atrophy
#3
Noriaki Kawanishi, Risa Nozaki, Hisashi Naito, Shuichi Machida
Recent studies have shown that activation of Toll-like receptor (TLR)4 signaling may be an important factor in muscle atrophy and excessive inflammatory response associated with immobilization. To examine the role of TLR4 signaling on cast immobilization-induced skeletal muscle atrophy, we tested the hypothesis that muscle atrophy and inflammation after cast immobilization is reduced in TLR4-defective mice. TLR4-defective (C3H/HeJ) and wild type (C3H/HeN) mice were divided into control and cast-immobilization groups...
April 2017: Physiological Reports
https://www.readbyqxmd.com/read/28432118/molecular-basis-for-exercise-induced-fatigue-the-importance-of-strictly-controlled-cellular-ca-2-handling
#4
Arthur J Cheng, Nicolas Place, Håkan Westerblad
The contractile function of skeletal muscle declines during intense or prolonged physical exercise, that is, fatigue develops. Skeletal muscle fibers fatigue acutely during highly intense exercise when they have to rely on anaerobic metabolism. Early stages of fatigue involve impaired myofibrillar function, whereas decreased Ca(2+) release from the sarcoplasmic reticulum (SR) becomes more important in later stages. SR Ca(2+) release can also become reduced with more prolonged, lower intensity exercise, and it is then related to glycogen depletion...
April 21, 2017: Cold Spring Harbor Perspectives in Medicine
https://www.readbyqxmd.com/read/28431604/a-reappraisal-of-diagnostic-tests-for-myasthenia-gravis-in-a-large-asian-cohort
#5
Yew Long Lo, Raymond P Najjar, Kelvin Y Teo, Sharon L Tow, Jing Liang Loo, Dan Milea
BACKGROUND: Myasthenia gravis (MG) is a chronic autoimmune neuromuscular disease characterized by weakness of bodily skeletal muscles. Office-based diagnostic tests such as repetitive nerve stimulation (RNS), single fiber electromyography (SFEMG), and the ice test, are used to refine the differential clinical diagnosis of this disease. Evaluating the clinical sensitivity and specificity of these tests, however, may be confounded by lack of a gold standard, non-blinding, incorporation bias, use of non-representative populations and retrospective data...
May 15, 2017: Journal of the Neurological Sciences
https://www.readbyqxmd.com/read/28429074/ultrastructure-of-pheochromocytoma-undescribed-morphologic-features
#6
A Beiras Fernandez, A Kornberger, M Fraga, C F Vahl, A Beiras
We examined samples of human pheochromocytoma from 11 patients aged 30-70 years including one case of malignant pheochromocytoma with a view to identifying previously unreported ultrastructural details.We identified two types of nuclear inclusions consisting of irregularly shaped singular or multiple granulofibrillar formations with a typical concentric halo, on the one hand, and accumulations of egg-shaped structures consisting of granules and microfilaments, on the other. In some of the tumor cells, membrane-covered inclusions containing parallel laminar elements arranged in a paracrystalline, periodic fashion, or mega-mitrochondriae characterized by increased electrodensity of their matrix, and fibrillary material in the spaces between the cristae were present...
April 20, 2017: Virchows Archiv: An International Journal of Pathology
https://www.readbyqxmd.com/read/28428630/hinge-deleted-igg4-blocker-therapy-for-acetylcholine-receptor-myasthenia-gravis-in-rhesus-monkeys
#7
Mario Losen, Aran F Labrijn, Vivianne H van Kranen-Mastenbroek, Maarten L Janmaat, Krista G Haanstra, Frank J Beurskens, Tom Vink, Margreet Jonker, Bert A 't Hart, Marina Mané-Damas, Peter C Molenaar, Pilar Martinez-Martinez, Eline van der Esch, Janine Schuurman, Marc H de Baets, Paul W H I Parren
Autoantibodies against ion channels are the cause of numerous neurologic autoimmune disorders. Frequently, such pathogenic autoantibodies have a restricted epitope-specificity. In such cases, competing antibody formats devoid of pathogenic effector functions (blocker antibodies) have the potential to treat disease by displacing autoantibodies from their target. Here, we have used a model of the neuromuscular autoimmune disease myasthenia gravis in rhesus monkeys (Macaca mulatta) to test the therapeutic potential of a new blocker antibody: MG was induced by passive transfer of pathogenic acetylcholine receptor-specific monoclonal antibody IgG1-637...
April 20, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28428485/pathological-lesions-in-the-central-nervous-system-and-peripheral-tissues-of-ddy-mice-with-street-rabies-virus-1088-strain
#8
Kazunori Kimitsuki, Kentaro Yamada, Nozomi Shiwa, Satoshi Inoue, Akira Nishizono, Chun-Ho Park
Most studies on rabies virus pathogenesis in animal models have employed fixed rabies viruses, and the results of those employing street rabies viruses have been inconsistent. Therefore, to clarify the pathogenesis of street rabies virus (1088 strain) in mice, 10(6) focus forming units were inoculated into the right hindlimb of ddY mice (6 weeks, female). At 3 days postinoculation (DPI), mild inflammation was observed in the hindlimb muscle. At 5 DPI, ganglion cells in the right lumbosacral spinal dorsal root ganglia showed chromatolysis...
April 20, 2017: Journal of Veterinary Medical Science
https://www.readbyqxmd.com/read/28426898/improving-myoblast-differentiation-on-electrospun-poly-%C3%AE%C2%B5-caprolactone-scaffolds
#9
Phammela N Abarzúa-Illanes, Cristina Padilla, Andrea Ramos, Mauricio Isaacs, Jorge Ramos-Grez, Hugo C Olguín, Loreto M Valenzuela
Polymer scaffolds are used as an alternative to support tissue regeneration when it does not occur on its own. Cell response on polymer scaffolds is determined by factors such as polymer composition, topology, and the presence of other molecules. We evaluated the cellular response of murine skeletal muscle myoblasts on aligned or unaligned fibers obtained by electrospinning poly(ε-caprolactone) (PCL), and blends with poly(lactic-co-glycolic acid) (PLGA) or decorin, a proteoglycan known to regulate myogenesis...
April 20, 2017: Journal of Biomedical Materials Research. Part A
https://www.readbyqxmd.com/read/28424630/hippo-pathway-and-skeletal-muscle-mass-regulation-in-mammals-a-controversial-relationship
#10
REVIEW
Olouyomi Gnimassou, Marc Francaux, Louise Deldicque
Skeletal muscle mass reflects a dynamic turnover between net protein synthesis and degradation. In addition, satellite cell inclusion may contribute to increase muscle mass while fiber loss results in a reduction of muscle mass. Since 2010, a few studies looked at the involvement of the newly discovered Hippo pathway in the regulation of muscle mass. In line with its roles in other organs, it has been hypothesized that the Hippo pathway could play a role in different regulatory mechanisms in skeletal muscle as well, namely proliferation and renewal of satellite cells, differentiation, death, and growth of myogenic cells...
2017: Frontiers in Physiology
https://www.readbyqxmd.com/read/28424626/a-rat-immobilization-model-based-on-cage-volume-reduction-a-physiological-model-for-bed-rest
#11
Enrica Marmonti, Sílvia Busquets, Míriam Toledo, Marina Ricci, Marc Beltrà, Victòria Gudiño, Francesc Oliva, José M López-Pedrosa, Manuel Manzano, Ricardo Rueda, Francisco J López-Soriano, Josep M Argilés
Bed rest has been an established treatment in the past prescribed for critically illness or convalescing patients, in order to preserve their body metabolic resource, to prevent serious complications and to support their rapid path to recovery. However, it has been reported that prolonged bed rest can have detrimental consequences that may delay or prevent the recovery from clinical illness. In order to study disuse-induced changes in muscle and bone, as observed during prolonged bed rest in humans, an innovative new model of muscle disuse for rodents is presented...
2017: Frontiers in Physiology
https://www.readbyqxmd.com/read/28417082/improving-glucose-tolerance-by-muscle-damaging-exercise
#12
Chien-Te Ho, Machiko Otaka, Chia-Hua Kuo
Tissue damage is regarded as an unwanted medical condition to be avoided. However, introducing tolerable tissue damages has been used as a therapeutic intervention in traditional and complementary medicine to cure discomfort and illness. Eccentric exercise is known to cause significant necrosis and insulin resistance of skeletal muscle. The purpose of this study was to determine the magnitude of muscle damage and blood glucose responses during an oral glucose tolerance test (OGTT) after eccentric training in 21 young participants...
April 2017: Journal of Traditional and Complementary Medicine
https://www.readbyqxmd.com/read/28416349/cytoplasmic-body-pathology-in-severe-acta1-related-myopathy-in-the-absence-of-typical-nemaline-rods
#13
Sandra Donkervoort, Sophelia H S Chan, Leslie H Hayes, Nathaniel Bradley, David Nguyen, Meganne E Leach, Payam Mohassel, Ying Hu, Mathula Thangarajh, Diana Bharucha-Goebel, Amanda Kan, Ronnie S L Ho, Christine A Reyes, Jessica Nance, Steven A Moore, A Reghan Foley, Carsten G Bönnemann
Mutations in ACTA1 cause a group of myopathies with expanding clinical and histopathological heterogeneity. We describe three patients with severe ACTA1-related myopathy who have muscle fiber cytoplasmic bodies but no classic nemaline rods. Patient 1 is a five-year-old boy who presented at birth with severe weakness and respiratory failure, requiring mechanical ventilation. Whole exome sequencing identified a heterozygous c.282C>A (p.Asn94Lys) ACTA1 mutation. Patients 2 and 3 were twin boys with hypotonia, severe weakness, and respiratory insufficiency at birth requiring mechanical ventilation...
March 2, 2017: Neuromuscular Disorders: NMD
https://www.readbyqxmd.com/read/28415893/rem-sleep-deprivation-impairs-muscle-regeneration-in-rats
#14
Marcos Mônico-Neto, Murilo Dáttilo, Daniel Araki Ribeiro, Kil Sun Lee, Marco Túlio de Mello, Sergio Tufik, Hanna Karen Moreira Antunes
INTRODUCTION: The aim was observe the influence of sleep deprivation (SD) and sleep recovery on muscle regeneration process in rats submitted to cryolesion. METHODS: Thirty-two Wistar rats were randomly allocated in four groups: control (CTL), SD for 96 h (SD96), control plus sleep recovery period (CTL + R) and SD96h plus 96 h of sleep recovery (SD96 + R). The animals were submitted to muscle injury by cryolesioning, after to SD and sleep recovery. RESULTS: The major outcomes of this study were the reduction of muscular IGF-1 in both legs (injured and uninjured) and a delay in muscle regeneration process of animals submitted to SD compared to animals that slept, with increase connective tissue, inflammatory infiltrate and minor muscle fibers...
April 17, 2017: Growth Factors
https://www.readbyqxmd.com/read/28412785/-functional-repair-of-cleft-lip-from-anatomical-resetting-to-biomechanical-simulation
#15
N B Yin
We are no longer entangled in the anatomical resetting of the labial-nasal muscle itself, but the sight to the muscle fiber level, to study the relationship between the muscle fiber force line and the labial-nasal shape. In the past ten years, we focused on the lip of nasal muscle fiber anatomy, imageology and biomechanics, carried out a series of research works, realized the three-dimensional (3D) visualization of small labial-nasal muscle fiber, established configuration models of normal and cleft lip with nasal muscle fibers, and put forward the hypothesis of naso-labial muscle tension band...
April 9, 2017: Zhonghua Kou Qiang Yi Xue za Zhi, Zhonghua Kouqiang Yixue Zazhi, Chinese Journal of Stomatology
https://www.readbyqxmd.com/read/28411958/effects-of-step-length-and-step-frequency-on-lower-limb-muscle-function-in-human-gait
#16
Yoong Ping Lim, Yi-Chung Lin, Marcus G Pandy
The aim of this study was to quantify the effects of step length and step frequency on lower-limb muscle function in walking. Three-dimensional gait data were used in conjunction with musculoskeletal modeling techniques to evaluate muscle function over a range of walking speeds using prescribed combinations of step length and step frequency. The body was modeled as a 10-segment, 21-degree-of-freedom skeleton actuated by 54 muscle-tendon units. Lower-limb muscle forces were calculated using inverse dynamics and static optimization...
March 21, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28410762/ultrasound-assessment-of-abdominal-muscle-thickness-in-women-with-and-without-low-back-pain-during-pregnancy
#17
Carol Ann Weis, Jennifer Nash, John J Triano, Jon Barrett
OBJECTIVE: The aim of this preliminary study was to determine the differences in abdominal musculature thickness, within 1 month of delivery, in women who experienced back pain during pregnancy compared with those who did not. METHODS: B-mode ultrasound imaging was used to measure abdominal muscle thickness on 76 postpartum participants who participated in a larger study; 47 women experienced back pain during pregnancy, and 29 did not. Participant data were stratified by group, and primary comparisons were based on these grouping across the abdominal muscles, including rectus abdominis (upper and lower fibers), external oblique, internal oblique, and transversus abdominis...
April 12, 2017: Journal of Manipulative and Physiological Therapeutics
https://www.readbyqxmd.com/read/28409313/extracellular-regulation-of-the-mitotic-spindle-and-fate-determinants-driving-asymmetric-cell-division
#18
Prestina Smith, Mark Azzam, Lindsay Hinck
Stem cells use mode of cell division, symmetric (SCD) versus asymmetric (ACD), to balance expansion with self-renewal and the generation of daughter cells with different cell fates. Studies in model organisms have identified intrinsic mechanisms that govern this process, which involves partitioning molecular components between daughter cells, frequently through the regulation of the mitotic spindle. Research performed in vertebrate tissues is revealing both conservation of these intrinsic mechanisms and crucial roles for extrinsic cues in regulating the frequency of these divisions...
2017: Results and Problems in Cell Differentiation
https://www.readbyqxmd.com/read/28408640/long-term-but-not-short-term-high-fat-diet-induces-fiber-composition-changes-and-impaired-contractile-force-in-mouse-fast-twitch-skeletal-muscle
#19
Hiroaki Eshima, Yoshifumi Tamura, Saori Kakehi, Nagomi Kurebayashi, Takashi Murayama, Kyoko Nakamura, Ryo Kakigi, Takao Okada, Takashi Sakurai, Ryuzo Kawamori, Hirotaka Watada
In this study, we investigated the effects of a short-term and long-term high-fat diet (HFD) on morphological and functional features of fast-twitch skeletal muscle. Male C57BL/6J mice were fed a HFD (60% fat) for 4 weeks (4-week HFD) or 12 weeks (12-week HFD). Subsequently, the fast-twitch extensor digitorum longus muscle was isolated, and the composition of muscle fiber type, expression levels of proteins involved in muscle contraction, and force production on electrical stimulation were analyzed. The 12-week HFD, but not the 4-week HFD, resulted in a decreased muscle tetanic force on 100 Hz stimulation compared with control (5...
April 2017: Physiological Reports
https://www.readbyqxmd.com/read/28408219/developing-dyrk-inhibitors-derived-from-the-meridianins-as-a-means-of-increasing-levels-of-nfat-in-the-nucleus
#20
Simon J Shaw, Dane A Goff, Nan Lin, Rajinder Singh, Wei Li, John McLaughlin, Kristen A Baltgalvis, Donald G Payan, Todd M Kinsella
A structure-activity relationship has been developed around the meridianin scaffold for inhibition of Dyrk1a. The compounds have been focussed on the inhibition of kinase Dyrk1a, as a means to retain the transcription factor NFAT in the nucleus. NFAT is responsible for up-regulation of genes responsible for the induction of a slow, oxidative skeletal muscle phenotype, which may be an effective treatment for diseases where exercise capacity is compromised. The SAR showed that while strong Dyrk1a binding was possible with the meridianin scaffold the compounds have no effect on NFAT localisation, however, by moving from the indole to a 6-azaindole scaffold both potent Dyrk1a binding and increased NFAT residence time in the nucleus were obtained - properties not observed with the reported Dyrk1a inhibitors...
March 18, 2017: Bioorganic & Medicinal Chemistry Letters
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