Subjects -> MEDICAL SCIENCES (Total: 8529 journals)
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MEDICAL SCIENCES (2342 journals)            First | 3 4 5 6 7 8 9 10 | Last

Showing 1201 - 1400 of 3562 Journals sorted alphabetically
Journal of Health Research and Reviews     Open Access  
Journal of Health Science and Medical Research     Open Access  
Journal of Health Science Research     Open Access  
Journal of Health Sciences     Open Access   (Followers: 1)
Journal of health sciences     Open Access  
Journal of Health Sciences / Sağlık Bilimleri Dergisi     Open Access  
Journal of Health Sciences and Medicine     Open Access  
Journal of Health Sciences and Surveillance System     Open Access  
Journal of Health Sciences Scholarship     Open Access  
Journal of Health Specialties     Open Access  
Journal of Health Studies     Open Access  
Journal of Healthcare Informatics Research     Hybrid Journal   (Followers: 1)
Journal of Heavy Metal Toxicity and Diseases     Open Access  
Journal of Helminthology     Hybrid Journal   (Followers: 2)
Journal of Herbs Spices & Medicinal Plants     Hybrid Journal  
Journal of HIV for Clinical and Scientific Research     Open Access   (Followers: 1)
Journal of Hospital Medicine     Hybrid Journal   (Followers: 10)
Journal of Huazhong University of Science and Technology [Medical Sciences]     Hybrid Journal  
Journal of Human Hypertension     Hybrid Journal   (Followers: 3)
Journal of Human Rhythm     Open Access  
Journal of Human Transcriptome     Open Access  
Journal of Ideas in Health     Open Access  
Journal of Inflammation     Open Access   (Followers: 2)
Journal of Inflammation Research     Open Access  
Journal of Injury and Violence Research     Open Access   (Followers: 7)
Journal of Innovation in Health Informatics     Open Access   (Followers: 17)
Journal of Institute of Medicine     Open Access  
Journal of Insulin Resistance     Open Access   (Followers: 1)
Journal of Interactional Research in Communication Disorders     Hybrid Journal   (Followers: 5)
Journal of Interferon & Cytokine Research     Hybrid Journal   (Followers: 3)
Journal of International Medical Research     Open Access   (Followers: 4)
Journal of Interventional Medicine     Open Access   (Followers: 1)
Journal of Investigative Medicine     Hybrid Journal   (Followers: 3)
Journal of Islamabad Medical & Dental College     Open Access  
Journal of Istanbul Faculty of Medicine     Open Access  
Journal of Karnali Academy of Health Sciences     Open Access   (Followers: 1)
Journal of Kathmandu Medical College     Open Access   (Followers: 1)
Journal of King Abdulaziz University : Medical Sciences     Open Access   (Followers: 2)
Journal of Laboratory Medicine     Hybrid Journal   (Followers: 27)
Journal of Laryngology and Voice     Open Access   (Followers: 11)
Journal of Lasers in Medical Sciences     Open Access  
Journal of Law, Medicine & Ethics     Hybrid Journal   (Followers: 24)
Journal of Legal Medicine     Hybrid Journal   (Followers: 7)
Journal of Limb Lengthening & Reconstruction     Open Access  
Journal of Lumbini Medical College     Open Access   (Followers: 1)
Journal of Mahatma Gandhi Institute of Medical Sciences     Open Access  
Journal of Manipulative and Physiological Therapeutics     Hybrid Journal   (Followers: 6)
Journal of Manmohan Memorial Institute of Health Sciences     Open Access   (Followers: 1)
Journal of Marine Medical Society     Open Access  
Journal of Materials Science : Materials in Medicine     Hybrid Journal   (Followers: 4)
Journal of Maternal and Child Health     Open Access  
Journal of Mechanics in Medicine and Biology     Hybrid Journal  
Journal of Medical and Biological Engineering     Hybrid Journal   (Followers: 4)
Journal of Medical and Biomedical Sciences     Open Access   (Followers: 2)
Journal of Medical Case Reports     Open Access   (Followers: 1)
Journal of Medical Cases     Open Access   (Followers: 6)
Journal of Medical Colleges of PLA     Full-text available via subscription  
Journal of Medical Disorders     Open Access  
Journal of Medical Economics     Hybrid Journal   (Followers: 8)
Journal of Medical Education and Curricular Development     Open Access   (Followers: 6)
Journal of Medical Ethics     Partially Free   (Followers: 25)
Journal of Medical Ethics and History of Medicine     Open Access   (Followers: 15)
Journal of Medical Humanities     Hybrid Journal   (Followers: 21)
Journal of Medical Hypotheses and Ideas     Open Access  
Journal of Medical Imaging and Health Informatics     Full-text available via subscription   (Followers: 1)
Journal of Medical Investigation and Practice     Open Access  
Journal of Medical Laboratory and Diagnosis     Open Access  
Journal of Medical Law and Ethics     Full-text available via subscription   (Followers: 15)
Journal of Medical Microbiology     Full-text available via subscription   (Followers: 6)
Journal of Medical Sciences     Open Access  
Journal of Medical Sciences     Open Access  
Journal of Medical Screening     Hybrid Journal   (Followers: 6)
Journal of Medical Signals and Sensors     Open Access   (Followers: 3)
Journal of Medical Society     Open Access  
Journal of Medical Systems     Hybrid Journal  
Journal of Medical Toxicology     Hybrid Journal   (Followers: 6)
Journal of Medical Ultrasound     Open Access   (Followers: 2)
Journal of Medicinal Botany     Open Access  
Journal of Medicinal Chemistry     Hybrid Journal   (Followers: 197)
Journal of Medicine     Open Access   (Followers: 1)
Journal of Medicine and Biomedical Research     Open Access   (Followers: 1)
Journal of Medicine and Philosophy     Hybrid Journal   (Followers: 8)
Journal of Medicine and the Person     Hybrid Journal  
Journal of Medicine in Scientific Research     Open Access  
Journal of Medicine in the Tropics     Open Access  
Journal of Medicine Research and Development     Open Access   (Followers: 3)
Journal of Medicine, Physiology and Biophysics     Open Access   (Followers: 5)
Journal of Medicines Development Sciences     Open Access   (Followers: 1)
Journal of Metabolomics & Systems Biology     Open Access  
Journal of Mind and Medical Sciences     Open Access   (Followers: 1)
Journal of Molecular Medicine     Hybrid Journal   (Followers: 11)
Journal of Movement Disorders     Open Access   (Followers: 2)
Journal of Muscle Research and Cell Motility     Hybrid Journal   (Followers: 1)
Journal of Nanotechnology in Engineering and Medicine     Full-text available via subscription   (Followers: 6)
Journal of Natural Medicines     Hybrid Journal  
Journal of Natural Science, Biology and Medicine     Open Access   (Followers: 3)
Journal of Nature and Science of Medicine     Open Access   (Followers: 4)
Journal of Negative and No Positive Results     Open Access  
Journal of Nepalgunj Medical College     Open Access  
Journal of Neurocritical Care     Open Access  
Journal of Neurodegenerative Diseases     Open Access   (Followers: 2)
Journal of Neurorestoratology     Open Access  
Journal of Neuroscience and Neurological Disorders     Open Access  
Journal of Nobel Medical College     Open Access  
Journal of Obesity and Bariatrics     Open Access  
Journal of Occupational Health     Open Access  
Journal of Occupational Therapy Education     Open Access   (Followers: 9)
Journal of Ocular Biology, Diseases, and Informatics     Hybrid Journal  
Journal of Oral Biology and Craniofacial Research     Full-text available via subscription  
Journal of Oral Health and Craniofacial Science     Open Access  
Journal of Orofacial Sciences     Open Access  
Journal of Otorhinolaryngology, Hearing and Balance Medicine     Open Access   (Followers: 1)
Journal of Ovarian Research     Open Access  
Journal of Ozone Therapy     Open Access  
Journal of Palliative Medicine     Hybrid Journal   (Followers: 47)
Journal of Paramedical Sciences & Rehabilitation     Open Access  
Journal of Parkinsonism and Restless Legs Syndrome     Open Access   (Followers: 2)
Journal of Parkinson’s Disease and Alzheimer’s Disease     Open Access  
Journal of Participatory Medicine     Open Access  
Journal of Patan Academy of Health Sciences     Open Access  
Journal of Pathogens     Open Access   (Followers: 1)
Journal of Patient Experience     Open Access  
Journal of Patient Safety and Risk Management     Hybrid Journal   (Followers: 1)
Journal of Patient-Centered Research and Reviews     Open Access  
Journal of Patient-Reported Outcomes     Open Access  
Journal of Periodontal Research     Hybrid Journal  
Journal of Personalized Medicine     Open Access   (Followers: 3)
Journal of Pest Science     Hybrid Journal   (Followers: 1)
Journal of Pharmaceutical Policy and Practice     Open Access   (Followers: 4)
Journal of Physiobiochemical Metabolism     Hybrid Journal   (Followers: 2)
Journal of Physiology-Paris     Hybrid Journal   (Followers: 2)
Journal of Pioneering Medical Sciences     Open Access  
Journal of Postgraduate Medicine     Open Access  
Journal of Pregnancy     Open Access   (Followers: 4)
Journal of Prevention & Intervention Community     Hybrid Journal   (Followers: 6)
Journal of Preventive Medicine and Public Health     Open Access  
Journal of Primary Prevention     Hybrid Journal   (Followers: 7)
Journal of Prosthodontic Research     Full-text available via subscription   (Followers: 1)
Journal of Prosthodontics     Hybrid Journal   (Followers: 2)
Journal of Receptor, Ligand and Channel Research     Open Access  
Journal of Regenerative Medicine     Partially Free   (Followers: 3)
Journal of Research in Medical Sciences     Open Access   (Followers: 2)
Journal of Science and Applications : Biomedicine     Open Access   (Followers: 1)
Journal of Science and Technology (Ghana)     Open Access   (Followers: 3)
Journal of Scientific Innovation in Medicine     Open Access  
Journal of Scientific Perspectives     Open Access   (Followers: 1)
Journal of Sensory Studies     Hybrid Journal   (Followers: 4)
Journal of Shaheed Suhrawardy Medical College     Open Access  
Journal of Shoulder and Elbow Arthroplasty     Open Access  
Journal of Sleep Disorders : Treatment & Care     Hybrid Journal   (Followers: 10)
Journal of South American Earth Sciences     Hybrid Journal   (Followers: 5)
Journal of Spinal Cord Medicine     Hybrid Journal   (Followers: 4)
Journal of Spinal Disorders & Techniques     Hybrid Journal   (Followers: 2)
Journal of Sports Medicine and Allied Health Sciences : Official Journal of the Ohio Athletic Trainers Association     Open Access   (Followers: 1)
Journal of Stem Cell Therapy and Transplantation     Open Access   (Followers: 1)
Journal of Stomal Therapy Australia     Full-text available via subscription  
Journal of Strength and Conditioning Research     Hybrid Journal   (Followers: 73)
Journal of Substance Use     Hybrid Journal   (Followers: 14)
Journal of Surgical Academia     Open Access   (Followers: 1)
Journal of Surgical and Clinical Research     Open Access  
Journal of Surgical Case Reports     Open Access  
Journal of Surgical Education     Full-text available via subscription   (Followers: 3)
Journal of Surgical Technique and Case Report     Open Access  
Journal of Systemic Therapies     Full-text available via subscription   (Followers: 3)
Journal of Taibah University Medical Sciences     Open Access  
Journal of Telemedicine and Telecare     Hybrid Journal   (Followers: 12)
Journal of The Academy of Clinical Microbiologists     Open Access  
Journal of the American Association for Laboratory Animal Science     Full-text available via subscription   (Followers: 7)
Journal of the American College of Certified Wound Specialists     Hybrid Journal   (Followers: 2)
Journal of the American College of Clinical Wound Specialists     Hybrid Journal   (Followers: 2)
Journal of the American Medical Directors Association     Hybrid Journal   (Followers: 6)
Journal of the American Medical Informatics Association : JAMIA     Hybrid Journal   (Followers: 35)
Journal of the American Podiatric Medical Association     Full-text available via subscription   (Followers: 7)
Journal of the Anatomical Society of India     Full-text available via subscription  
Journal of the Anus, Rectum and Colon     Open Access  
Journal of The Arab Society for Medical Research     Open Access  
Journal of the Australasian College of Nutritional and Environmental Medicine     Full-text available via subscription  
Journal of the Australasian Society of Aerospace Medicine     Open Access   (Followers: 1)
Journal of the Ceylon College of Physicians     Open Access  
Journal of the Chinese Medical Association     Open Access   (Followers: 2)
Journal of the College of Community Physicians of Sri Lanka     Open Access  
Journal of The Egyptian Public Health Association     Open Access   (Followers: 1)
Journal of the Formosan Medical Association     Open Access   (Followers: 2)
Journal of the Ghana Science Association     Full-text available via subscription   (Followers: 3)
Journal of the Grodno State Medical University     Open Access   (Followers: 1)
Journal of the History of Medicine and Allied Sciences     Hybrid Journal   (Followers: 17)
Journal of the International Society for Telemedicine and eHealth     Open Access   (Followers: 3)
Journal of the Learning Sciences     Hybrid Journal   (Followers: 17)
Journal of the Medical Library Association     Open Access   (Followers: 284)
Journal of the Medical Sciences (Berkala ilmu Kedokteran)     Open Access   (Followers: 1)
Journal of the National Medical Association     Full-text available via subscription  
Journal of the Peripheral Nervous System     Hybrid Journal   (Followers: 3)
Journal of the Postgraduate Institute of Medicine     Open Access  
Journal of the Renin-Angiotensin-Aldosterone System     Open Access   (Followers: 1)
Journal of the Royal Society of Medicine     Hybrid Journal   (Followers: 2)
Journal of the Ruhunu Clinical Society     Open Access  
Journal of the Scientific Society     Open Access   (Followers: 1)
Journal of the Siena Academy of Sciences     Open Access   (Followers: 1)
Journal of Therapeutic Ultrasound     Open Access  
Journal of Thyroid Research     Open Access   (Followers: 1)

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Similar Journals
Journal Cover
Journal of Muscle Research and Cell Motility
Journal Prestige (SJR): 0.936
Citation Impact (citeScore): 2
Number of Followers: 1  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0142-4319 - ISSN (Online) 1573-2657
Published by Springer-Verlag Homepage  [2626 journals]
  • Obituary: Sumiko Kimura 1947–2018
    • PubDate: 2019-03-22
       
  • A mechanical model of the half-sarcomere which includes the contribution
           of titin
    • Abstract: The evidence, in both resting and active muscle, for the presence of an I-band spring element like titin that anchors the Z line to the end of the thick filament did not yet produce a proper theoretical treatment in a complete model of the half-sarcomere. The textbook model developed by A. F. Huxley and his collaborators in 1981, which provides that the half-sarcomere (hs) compliance is due to the contribution of the compliances of the thin and thick filaments and actin-attached myosin motors, predicts that at any sarcomere length (SL) the absence of attached motors results in an infinite half-sarcomere compliance, in contrast with the observations. Growing evidence for the presence of a titin-like I-band spring urges the 1981 model to be implemented to include the contribution of this element in the mechanical model of the half-sarcomere. The model described here represents a tool for the interpretation of measurements of hs stiffness at increasing SL, which is important either in relation to the mechanism of stabilisation of SL against the consequence of sarcomere inhomogeneity in active force generation, or for investigations on the role of titin as mechano-sensor in thick filament regulation. Moreover the model opens the possibility for understanding the functional differences related to the titin isoform of various muscle types and the mechanism by which mutations in titin gene lead to myopathies.
      PubDate: 2019-03-21
       
  • Baboon ( Papio ursinus ) single fibre contractile properties are similar
           to that of trained humans
    • Abstract: This study investigated the contractile properties of single skeletal muscle fibres from the Vastus lateralis (VL) of two male adult chachma baboons (Papio ursinus) and compared it to that from five male human cyclists. Species comparisons are observational and statistical analyses were not performed due to the low sample size. The histological analyses revealed that the baboon muscles contained more type II fibres than their human counterparts. Cross-sectional areas of type I and type II fibres from human VL were similar in size, whereas baboon type I and type II fibres appeared smaller and larger compared to humans, respectively. On average, type II fibres from baboons and type IIAX fibres from humans produced the highest specific force (88 ± 41 and 155 ± 4 kN/m2, respectively), compared to 57 ± 27 and 68 ± 5 kN/m2 for baboon and human type I fibres. Maximum shortening velocity appeared highest in human type IIAX fibres, but fairly similar between human and baboon type I and II fibres. Baboon and human type I (2.2 ± 0.4 vs. 1.5 ± 0.5 kN/m2 Fl/s) and type II (6.0 ± 2.8 vs. 7.7 ± 1.0 kN/m2 Fl/s) fibres appeared similar in maximum power output. From these observations, it seems that baboon and human muscle fibre contractile properties appear similar to one another, and that fibre type composition itself may play a determining role in muscle strength between these two species.
      PubDate: 2019-03-20
       
  • Proteomic profiling of the mouse diaphragm and refined mass spectrometric
           analysis of the dystrophic phenotype
    • Abstract: The diaphragm is a crucial muscle involved in active inspiration and whole body homeostasis. Previous biochemical, immunochemical and cell biological investigations have established the distribution and fibre type-specific expression of key diaphragm proteins. Building on these findings, it was of interest to establish the entire experimentally assessable diaphragm proteome and verify the presence of specific protein isoforms within this specialized subtype of skeletal muscle. A highly sensitive Orbitrap Fusion Tribrid mass spectrometer was used for the systematic identification of the mouse diaphragm-associated protein population. Proteomics established 2925 proteins by high confidence peptide identification. Bioinformatics was used to determine the distribution of the main protein classes, biological processes and subcellular localization within the diaphragm proteome. Following the establishment of the respiratory muscle proteome with special emphasis on protein isoform expression in the contractile apparatus, the extra-sarcomeric cytoskeleton, the extracellular matrix and the excitation–contraction coupling apparatus, the mass spectrometric analysis of the diaphragm was extended to the refined identification of proteome-wide changes in X-linked muscular dystrophy. The comparative mass spectrometric profiling of the dystrophin-deficient diaphragm from the mdx-4cv mouse model of Duchenne muscular dystrophy identified 289 decreased and 468 increased protein species. Bioinformatics was employed to analyse the clustering of changes in protein classes and potential alterations in interaction patterns of proteins involved in metabolism, the contractile apparatus, proteostasis and the extracellular matrix. The detailed pathoproteomic profiling of the mdx-4cv diaphragm suggests highly complex alterations in a variety of crucial cellular processes due to deficiency in the membrane cytoskeletal protein dystrophin.
      PubDate: 2019-03-19
       
  • Comparative analysis of widely used methods to remove nonfunctional myosin
           heads for the in vitro motility assay
    • Abstract: The in vitro motility assay allows studies of muscle contraction through observation of actin filament propulsion by surface-adsorbed myosin motors or motor fragments isolated from muscle. A possible problem is that motility may be compromised by nonfunctional, “dead”, motors, obtained in the isolation process. Here we investigate the effects on motile function of two approaches designed to eliminate the effects of these dead motors. We first tested the removal of heavy meromyosin (HMM) molecules with ATP-insensitive “dead” heads by pelleting them with actin filaments, using ultracentrifugation in the presence of 1 mM MgATP (“affinity purification”). Alternatively we incubated motility assay flow cells, after HMM surface adsorption, with non-fluorescent “blocking actin” (1 µM) to block the dead heads. Both affinity purification and use of blocking actin increased the fraction of motile filaments compared to control conditions. However, affinity purification significantly reduced the actin sliding speed in five out of seven experiments on silanized surfaces and in one out of four experiments on nitrocellulose surfaces. Similar effects on velocity were not observed with the use of blocking actin. However, a reduced speed was also seen (without affinity purification) if HMM or myosin subfragment 1 was mixed with 1 mM MgATP before and during surface adsorption. We conclude that affinity purification can produce unexpected effects that may complicate the interpretation of in vitro motility assays and other experiments with surface adsorbed HMM, e.g. single molecule mechanics experiments. The presence of MgATP during incubation with myosin motor fragments is critical for the complicating effects.
      PubDate: 2019-03-08
       
  • Increase in phospholamban content in mouse skeletal muscle after
           denervation
    • Abstract: It is well-known that denervation of motor nerves induces atrophy and decreases contractile force of the skeletal muscle. However, it is not completely understood how denervation alters calcium handling in the skeletal muscle. We investigated the effect of denervation on the expression and function of proteins involved in calcium handling. Two weeks after denervation of the right sciatic nerve in mice, we observed a significant decrease in mass and cross-sectional area of the ipsilateral tibialis anterior (TA) and flexor digitorum brevis (FDB) muscles. Also, we observed a significant decrease in the specific tetanus contractile force in the ipsilateral TA muscle. Calcium imaging of the ipsilateral FDB showed that the peak twitch and tetanus calcium concentrations were significantly decreased due to a decrease in calcium content of the sarcoplasmic reticulum (SR). Denervation reduced the maximum rate of sarcoplasmic/endoplasmic calcium ATPase (SERCA) activity. Interestingly, the amount of phospholamban (PLN), but not its transcripts, was increased in the ipsilateral vs. contralateral side after denervation, suggesting that denervation impairs constitutive regulation of PLN. Immunohistochemical analysis revealed increased PLN in all major fiber types in TA with IIx fibers showing a threefold higher expression than the contralateral side. These results suggest that the abnormal increase in PLN in the ipsilateral fast-twitch fibers may be involved in decreased SERCA activity, SR calcium content, peak calcium transients, and contractile forces of denervated muscles.
      PubDate: 2019-02-26
       
  • A new twist on tropomyosin binding to actin filaments: perspectives on
           thin filament function, assembly and biomechanics
    • Abstract: Tropomyosin, best known for its role in the steric regulation of muscle contraction, polymerizes head-to-tail to form cables localized along the length of both muscle and non-muscle actin-based thin filaments. In skeletal and cardiac muscles, tropomyosin, under the control of troponin and myosin, moves in a cooperative manner between blocked, closed and open positions on filaments, thereby masking and exposing actin-binding sites necessary for myosin crossbridge head interactions. While the coiled-coil signature of tropomyosin appears to be simple, closer inspection reveals surprising structural complexity required to perform its role in steric regulation. For example, component α-helices of coiled coils are typically zippered together along a continuous core hydrophobic stripe. Tropomyosin, however, contains a number of anomalous, functionally controversial, core amino acid residues. We argue that the atypical residues at this interface, including clusters of alanines and a charged aspartate, are required for preshaping tropomyosin to readily fit to the surface of the actin filament, but do so without compromising tropomyosin rigidity once the filament is assembled. Indeed, persistence length measurements of tropomyosin are characteristic of a semi-rigid cable, in this case conducive to cooperative movement on thin filaments. In addition, we also maintain that tropomyosin displays largely unrecognized and residue-specific torsional variance, which is involved in optimizing contacts between actin and tropomyosin on the assembled thin filament. Corresponding twist-induced stiffness may also enhance cooperative translocation of tropomyosin across actin filaments. We conclude that anomalous core residues of tropomyosin facilitate thin filament regulatory behavior in a multifaceted way.
      PubDate: 2019-02-15
       
  • A brief history of M. C. Schaub’s legacies: a life dedicated to
           heart and muscle research
    • PubDate: 2018-08-01
       
  • Acidosis affects muscle contraction by slowing the rates myosin attaches
           to and detaches from actin
    • Abstract: The loss of muscle force and power during fatigue from intense contractile activity is associated with, and likely caused by, elevated levels of phosphate ( \(\mathrm {P}_{\mathrm{i}}\) ) and hydrogen ions (decreased pH). To understand how these deficits in muscle performance occur at the molecular level, we used direct measurements of mini-ensembles of myosin generating force in the laser trap assay at pH 7.4 and 6.5. The data are consistent with a mechanochemical model in which a decrease in pH reduces myosin’s detachment from actin (by slowing ADP release), increases non-productive myosin binding (by detached myosin rebinding without a powerstroke), and reduces myosin’s attachment to actin (by slowing the weak-to-strong binding transition). Additional support of this mechanism is found by incorporating it into a branched pathway model for the effects of \(\mathrm {P}_{\mathrm{i}}\) on myosin’s interaction with actin. Including pH-dependence in one additional parameter (acceleration of \(\mathrm {P}_{\mathrm{i}}\) -induced detachment), the model reproduces experimental measurements at high and low pH, and variable \(\mathrm {P}_{\mathrm{i}}\) , from the single molecule to large ensemble levels. Furthermore, when scaled up, the model predicts force-velocity relationships that are consistent with muscle fiber measurements. The model suggests that reducing pH has two opposing effects, a decrease in attachment favoring a decrease in muscle force and a decrease in detachment favoring an increase in muscle force. Depending on experimental details, the addition of \(\mathrm {P}_{\mathrm{i}}\) can strengthen one or the other effect, resulting in either synergistic or antagonistic effects. This detailed molecular description suggests a molecular basis for contractile failure during muscle fatigue.
      PubDate: 2018-08-01
       
  • Specific effects of neuregulin-1β on the communication between DRG
           neurons and skeletal muscle cells in vitro
    • Abstract: The communication between primary afferent neuron and skeletal muscle (SKM) is one of the important factors on maintaining the structure and function of SKM cells. Neuregulin-1β (NRG-1β) signaling is essential for regulating synaptic neurotransmission. Here, we established a neuromuscular coculture model of dorsal root ganglion (DRG) sensory neurons and SKM cells to explore the nerve-muscle communication in the presence of exogenous NRG-1β. The expression of three distinct subtypes (TrkA, TrkB, and TrkC) of tyrosine kinase receptors was monitored for the phenotypical alterations of the neurons. The aggregation extent of acetylcholine receptor (AChR) represents the specific changes of SKM cells after NRG-1β incubation in this neuromuscular coculture model. The results showed that NRG-1β not only enhanced neurite outgrowth of DRG neurons but also increased the length and branches of SKM cells. NRG-1β treatment not only induced expression of all the three subtypes of Trk receptors in neurons but also promoted AChR aggregation on the surface of SKM cells. The effects of NRG-1β could be blocked by administration of ERK1/2 inhibitor PD98059, PI3K inhibitor LY294002, and JAK2 inhibitor AG490, respectively. These data imply that NRG-1β is essential for the nerve-muscle communication by enhancing growth and modifying phenotypes of the two different kinds of cells. The specific effects produced by NRG-1β add novel interpretation for nerve-muscle communication between sensory neurons and SKM cells.
      PubDate: 2018-08-01
       
  • 47th European Muscle Conference in Budapest, Hungary
    • PubDate: 2018-08-01
       
  • The expression of aquaporin-4 is regulated based on innervation in
           skeletal muscles
    • Authors: Minenori Ishido; Tomohiro Nakamura
      Abstract: Aquaporin-4 (AQP4) is a selective water channel, which expresses on the plasma membrane of myofibers and regulates the osmotic pressure, energy metabolism and morphological changes in myofibers by modulating water transport across sarcolemma in skeletal muscles. Although the physiological roles of AQP4 have been gradually clarified in skeletal muscles, the regulatory mechanisms of AQP4 expression have been poorly understood in skeletal muscles. Recently, it was reported that the expression of AQP4 decreased in atrophied skeletal muscles following sciatic nerve transection, but not tail-suspension. Therefore, expecting that the nerve supply to myofibers would be one of the major regulatory factors regulating AQP4 expression in skeletal muscles, we investigated whether the expression patterns of AQP4 were changed in skeletal muscles by denervation and subsequent reinnervation. As a result, while the APQ4 expression levels were significantly decreased by sciatic nerve freezing-induced denervation, subsequently the expression levels of AQP4 were fully restored during reinnervation in skeletal muscles (p < 0.05, respectively). On the other hand, the expression levels of α1-syntrophin and AQP1, which are respectively structural and functional related AQP4 factors, were stably maintained during the denervation and subsequent reinnervation. Therefore, the present study demonstrated that the expression of AQP4 may be regulated depending on the innervation to skeletal muscles. Moreover, AQP4 regulatory mechanisms may be fundamentally different to those of AQP1 in skeletal muscles.
      PubDate: 2018-06-04
      DOI: 10.1007/s10974-018-9494-z
       
  • Cold shock protein RBM3 attenuates atrophy and induces hypertrophy in
           skeletal muscle
    • Abstract: RNA-binding motif protein 3 (RBM3), a stress-inducible RNA-binding protein that increases protein synthesis and confers cell protection in multiple cell types, has been identified as a possible regulator of skeletal muscle mass. Therefore, the primary aim of this study was to examine the impact of elevated RBM3 on skeletal muscle hypertrophy and resistance to atrophy. Plasmid-mediated overexpression of RBM3 in vitro and in vivo was used to assess the role of RBM3 in muscle. C2C12 myotubes overexpressing RBM3 were approximately 1.6 times larger than non-transfected myotubes, suggesting a role for RBM3 in hypertrophy. In addition, elevated RBM3 attenuated atrophy in myotubes exposed to dexamethasone. In agreement with in vitro results, overexpression of RBM3 in soleus muscle of F344/BN rats using electroporation techniques increased the cross sectional area of muscle fibers. Overexpression of RBM3 also attenuated muscle atrophy in rat soleus muscle undergoing disuse atrophy. These findings provide direct evidence for a novel role of RBM3 in inducing hypertrophy as well as attenuating atrophy.
      PubDate: 2018-04-01
       
  • BGP-15 improves contractile function of regenerating soleus muscle
    • Abstract: This study investigated the effect of the heat shock protein inducer O-[3-piperidino-2-hydroxy-1-propyl]-nicotinic amidoxime (BGP-15) on the morphology and contractile function of regenerating soleus muscles from mice. Cryolesioned soleus muscles from young mice treated daily with BGP-15 (15 mg/Kg) were evaluated on post-cryolesion day 10. At this time point, there was a significant decrease in the cross-sectional area of regenerating myofibers, maximal force, specific tetanic force, and fatigue resistance of regenerating soleus muscles. BGP-15 did not reverse the decrease in myofiber cross-sectional area but effectively prevented the reduction in tetanic force and fatigue resistance of regenerating muscles. In addition, BGP-15 treatment increased the expression of embryonic myosin heavy chain (e-MyHC), MyHC-II and MyHC-I in regenerating muscles. Although BGP-15 did not alter voltage dependent anion-selective channel 2 (VDAC2) expression in cryolesioned muscles, it was able to increase inducible 70-kDa heat shock protein (HSP70) expression. Our results suggest that BGP-15 improves strength recovery in regenerating soleus muscles by accelerating the re-expression of adult MyHC-II and MyHC-I isoforms and HSP70 induction. The beneficial effects of BGP-15 on the contractile function of regenerating muscles reinforce the potential of this molecule to be used as a therapeutic agent.
      PubDate: 2018-04-01
       
  • Physiological and biochemical characteristics of skeletal muscles in
           sedentary and active rats
    • Abstract: Laboratory rats are sedentary if housed in conditions where activity is limited. Changes in muscle characteristics with chronic inactivity were investigated by comparing sedentary rats with rats undertaking voluntary wheel running for either 6 or 12 weeks. EDL (type II fibers) and soleus (SOL) muscles (predominantly type I fibers) were examined. When measured within 1–2 h post-running, calcium sensitivity of the contractile apparatus was increased, but only in type II fibers. This increase disappeared when fibers were treated with DTT, indicative of oxidative regulation of the contractile apparatus, and was absent in fibers from rats that had ceased running 24 h prior to experiments. Specific force production was ~ 10 to 25% lower in muscle fibers of sedentary compared to active rats, and excitability of skinned fibers was decreased. Muscle glycogen content was ~ 30% lower and glycogen synthase content ~ 50% higher in SOL of sedentary rats, and in EDL glycogenin was 30% lower. Na+, K+-ATPase α1 subunit density was ~ 20% lower in both EDL and SOL in sedentary rats, and GAPDH content in SOL ~ 35% higher. There were no changes in content of the calcium handling proteins calsequestrin and SERCA, but the content of CSQ-like protein was increased in active rats (by ~ 20% in EDL and 60% in SOL). These findings show that voluntary exercise elicits an acute oxidation-induced increase in Ca2+ sensitivity in type II fibers, and also that there are substantial changes in skeletal muscle characteristics and biochemical processes in sedentary rats.
      PubDate: 2018-04-01
       
  • A study of the mechanisms of excitation–contraction coupling in frog
           skeletal muscle based on measurements of [Ca 2+ ] transients inside the
           sarcoplasmic reticulum
    • Abstract: [Ca2+] transients inside the sarcoplasmic reticulum (SR) were recorded in frog skeletal muscle twitch fibers under voltage clamp using the low affinity indicator Mag Fluo 4 (loaded in its AM form) with the purpose of studying the effect on Ca2+ release of extrinsic Ca2+ buffers (i.e. BAPTA) added at high concentration to the myoplasm. When the extrinsic Ca2+ buffer is added to the myoplasm, part of the released Ca2+ binds to it, reducing the Ca2+ signal reported by a myoplasmic indicator. This, in turn, hinders the quantification of the amount of Ca2+ released. Monitoring release by measuring [Ca2+] inside the SR avoids this problem. The application of extrinsic buffers at high concentration reduced the resting [Ca2+] in the SR ([Ca2+]SR) continuously from a starting value close to 400 μM reaching the range of 100 μM in about half an hour. The effect of reducing resting [Ca2+]SR on the Ca2+ permeability of the SR activated by voltage clamp depolarization to 0 mV was studied in cells where the myoplasmic [Ca2+] ([Ca2+]myo) transients were simultaneously recorded with Rhod2. The Ca2+ release flux was calculated from [Ca2+]myo and divided by [Ca2+]SR to obtain the permeability. Peak permeability was significantly reduced, from 0.026 ± 0.005 ms−1 at resting [Ca2+]SR = 372 ± 5 μM to 0.021 ± 0.004 ms−1 at resting [Ca2+]SR = 120 ± 16 μM (n = 4, p = 0.03). The time averaged permeability was not significantly changed (0.009 ± 0.003 and 0.010 ± 0.003 ms−1, at the higher and lower [Ca2+]SR respectively). Once the cells were equilibrated with the high buffer intracellular solution, the change in [Ca2+]SR (Δ[Ca2+]SR) in response to voltage clamp depolarization (0 mV, 200 ms) in 20 mM BAPTA was significantly lower (Δ[Ca2+]SR = 30.2 ± 3.5 μM from resting [Ca2+]SR = 88.8 ± 13.6 μM, n = 5) than in 40 mM EGTA (Δ[Ca2+]SR = 72.2 ± 10.4 μM from resting [Ca2+]SR = 98.2 ± 15.6 μM, n = 4) suggesting that a Ca2+ activated component of release was suppressed by BAPTA.
      PubDate: 2018-04-01
       
  • Development of apical hypertrophic cardiomyopathy with age in a transgenic
           mouse model carrying the cardiac actin E99K mutation
    • Authors: Li Wang; Fan Bai; Qing Zhang; Weihua Song; Andrew Messer; Masataka Kawai
      Abstract: In both humans and mice, the Glu-99-Lys (E99K) mutation in the cardiac actin gene (ACTC) results in little understood apical hypertrophic cardiomyopathy (AHCM). To determine how cross-bridge kinetics change with AHCM development, we applied sinusoidal length perturbations to skinned papillary muscle fibres from 2- and 5-month old E99K transgenic (Tg) and non-transgenic (NTg) mice, and studied tension and its transients. These age groups were chosen because our preliminary studies indicated that AHCM develops with age. Fibres from 5-month old E99K mice showed significant decreases in tension, stiffness, the rate of the medium-speed exponential process and its magnitude compared to non-transgenic control. The nucleotide association constants increased with age, and they were significantly larger in E99K compared to NTg. However, there were no large differences in the rates of the cross-bridge detachment step, the rates of the force generation step, or the phosphate association constant. Our result on force/cross-bridge demonstrates that the decreased active tension of E99K fibres was caused by a decreased amount of force generated per each cross-bridge. The effects were generally less or insignificant at 2 months. A pCa-tension study showed increased Ca2+-sensitivity (pCa50) with age in both the E99K and NTg sample groups, and pCa50 was significantly larger (but only for 0.05–0.06 pCa units) in E99K than in NTg groups. A significant decrease in cooperativity (nH) was observed only in 5-month old E99K mice. We conclude that the AHCM-causing ACTC E99K mutation is associated with progressive alterations in biomechanical parameters, with changes smaller at 2 months but larger at 5 months, correlating with the development of AHCM.
      PubDate: 2018-03-26
      DOI: 10.1007/s10974-018-9492-1
       
  • Hans-Christoph Lüttgau 20 July 1926–5 November 2017
    • Authors: D. George Stephenson; David J. Miller
      PubDate: 2018-03-15
      DOI: 10.1007/s10974-018-9491-2
       
  • Changes in contractile and metabolic parameters of skeletal muscle as rats
           age from 3 to 12 months
    • Authors: Hongyang Xu; Graham D. Lamb; Robyn M. Murphy
      Abstract: 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- (~ 0.04 pCa units) and slow-twitch (~ 0.07 pCa units) muscle fibres, and specific force increased (by ~ 50% and ~ 25%, respectively). Myosin heavy chain composition of EDL and SOL muscles altered to a small extent with age (decrease in MHCIIa proportion after 3 months). Glycogen content increased with age (~ 80% in EDL and 25% in SOL) and GLUT4 protein density decreased (~ 35 and 20%, respectively), whereas the glycogen-related enzymes were little changed. GAPDH protein content was relatively constant in both muscle types, but COXIV protein decreased ~ 40% in SOL muscle. Calsequestrin (CSQ) and SERCA densities remained relatively constant with age, whereas there was a progressive ~ 2–3 fold increase in CSQ-like proteins, though their role and importance remain unclear. There was also ~ 40% decrease in the density of the Na+, K+-ATPase (NKA) α1 subunit in EDL and the α2 subunit in SOL. These findings emphasise there are substantial changes in skeletal muscle function and the density of key proteins during early to mid-adulthood in rats, which need to be considered in the design and interpretation of experiments.
      PubDate: 2017-11-28
      DOI: 10.1007/s10974-017-9484-6
       
  • Anisotropic mechanosensitive pathways in the diaphragm and their
           implications in muscular dystrophies
    • Authors: Patricia S. Pardo; Michael A. Lopez; Junaith S. Mohamed; Aladin M. Boriek
      Abstract: The diaphragm is the “respiratory pump;” the muscle that generates pressure to allow ventilation. Diaphragm muscles play a vital function and thus are subjected to continuous mechanical loading. One of its peculiarities is the ability to generate distinct mechanical and biochemical responses depending on the direction through which the mechanical forces applied to it. Contractile forces originated from its contractile components are transmitted to other structural components of its muscle fibers and the surrounding connective tissue. The anisotropic mechanical properties of the diaphragm are translated into biochemical signals that are directionally mechanosensitive by mechanisms that appear to be unique to this muscle. Here, we reviewed the current state of knowledge on the biochemical pathways regulated by mechanical signals emphasizing their anisotropic behavior in the normal diaphragm and analyzed how they are affected in muscular dystrophies.
      PubDate: 2017-10-06
      DOI: 10.1007/s10974-017-9483-7
       
 
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