Search results for "Muscle Fibers"
showing 10 items of 94 documents
Age affects myosin relaxation states in skeletal muscle fibers of female but not male mice
2018
The recent discovery that myosin has two distinct states in relaxed muscle–disordered relaxed (DRX) and super-relaxed (SRX)–provides another factor to consider in our fundamental understanding of the aging mechanism in skeletal muscle, since myosin is thought to be a potential contributor to dynapenia (age-associated loss of muscle strength independent of atrophy). The primary goal of this study was to determine the effects of age on DRX and SRX states and to examine their sex specificity. We have used quantitative fluorescence microscopy of the fluorescent nucleotide analog 2′/3′-O-(N-methylanthraniloyl) ATP (mantATP) to measure single-nucleotide turnover kinetics of myosin in skinned skel…
Celiac disease and selective immunoglobulin A deficiency
1997
Selective IgA deficiency was observed in 12 of 688 (1.7%) patients with celiac disease who were clinically undistinguishable from patients with celiac disease with normal IgA levels. This high prevalence of IgA deficiency in patients with celiac disease makes serum IgA assay advisable when screening for celiac disease is performed by measurement of antigliadin antibodies or anti-IgA endomysium antibodies. Similarly, subjects with IgA deficiency should be considered at risk of celiac disease.
Role of skeletal muscle-fibre type in regulation of glucose metabolism in middle-aged subjects with impaired glucose tolerance during a long-term exe…
2005
Aim: The aim of this study was to investigate the role of skeletal muscle fibre type in the regulation of glucose metabolism in middle-aged obese subjects with impaired glucose tolerance (IGT) during a 2-year exercise anddietary intervention. Methods: Muscle biopsies (musculus vastus lateralis) were taken from 22 subjects belonging to the intervention group of the Finnish Diabetes Prevention Study [1]. According to their myosin heavy chain (MHC) profile at the baseline, the subjects were divided into two groups: IGT s l o w (n = 10) with a high proportion of MHC I isoforms and IGT f a s t (n = 12) with a high proportion of MHC II isoforms in the vastus lateralis muscle. The intervention con…
The relative contribution to the plantar-flexor torque of the soleus motor units activated by the H reflex and M response in humans.
2000
Abstract This study proposes a method of quantifying the relative contribution to the plantar-flexor torque of soleus H and M responses evoked by tibial nerve stimulation. For ten subjects, the amplitude of the twitch produced by the H wave was plotted against the corresponding potential, for stimuli producing H without M (i.e. in the ascending portion of the H-recruitment curve). It was then assumed that the contribution of H to twitches produced by M plus H was similar for similar H waves on the curve-descending portion. Hence, the contribution of M was estimated, for the range of M waves including those accompanying H max . The estimated mechanical contributions of H and M wave increase …
Calf Blood Compound (CFC) and Homeopathic Drug Induce Differentiation of Primary Human Skeletal Muscle Cells.
2019
AbstractThe use of injections to treat structural muscle injuries is controversially discussed. In our controlled in vitro study, we investigated the biological impact of Actovegin and Traumeel alone and in combination on primary human skeletal muscle cells. Cells were characterized by immunofluorescence staining for myogenic factor 5 (Myf5) and MyoD, and cultured with or without Actovegin and / or Traumeel. The effects of these agents were assayed by cell viability and gene expression of the specific markers MyoD, Myf5, neural adhesion molecule (NCAM), and CD31. Myotube formation was determined by myosin staining. Neither Actovegin nor Traumeel showed toxic effects or influenced cell viabi…
Behavior of fascicles and the myotendinous junction of human medial gastrocnemius following eccentric strength training
2009
This study is the first in which measurements of thickness, fascicle angle and length, and tendon elongation were combined to examine the impact of eccentric strength training on both muscle architecture and tendinous structures. Eighteen healthy male subjects were divided into an eccentric strength training group (n = 10) and a control group (n = 8). The training program consisted of 18 sessions of eccentric exercises over a 7-week period. All subjects were tested at baseline and after the last training session. Using ultrasound imaging, the fascicle angle and length and thickness of the medial gastrocnemius (MG) were analyzed at rest (i.e., theta(p), Fl(p), and t(p), respectively), at 50%…
The cell-specific expression of metalloproteinase-disintegrins (ADAMs) in inflammatory myopathies
2007
Inflammatory cell invasion and cytokine activation are important steps in the pathogenesis of immune-mediated diseases of muscle. Metalloproteinase-disintegrins (ADAMs) are considered to play a critical role in leukocyte migration by promoting cellular adhesion, cleavage of molecules of the extracellular matrix and shedding of membrane bound cytokines. Here, we report the expression patterns of ADAM8, ADAM9, ADAM10, ADAM12, ADAM17 and ADAM19 in cultured human myoblasts and peripheral blood mononuclear cells (PBMCs) in vitro, as well as in biopsies from patients suffering from polymyositis (PM), dermatomyositis (DM), inclusion body myositis (IBM) and non-inflammatory controls. We observed an…
Medial gastrocnemius muscle behavior during human running and walking.
2007
Utilization of elastic energy in the tendinous tissues (TT) of the human skeletal muscle may be task dependent. The present study was designed to investigate this problem by comparing the fascicle-TT interaction of the medial gastrocnemius muscle (MG) during ground contact of running and walking. Seven subjects ran and walked with a natural cadence. Ankle and knee joint angular data were recorded by electrogoniometers for estimating the entire MG muscle-tendon unit (MTU) length, together with the ground reaction forces. The MG fascicle length was measured by using the high-speed ultrasound image scanning during movements. The results showed that in running, after the rapid early fascicle st…
Interaction between fascicle and tendinous tissues in short-contact stretch-shortening cycle exercise with varying eccentric intensities
2005
The interaction between fascicle and tendinous tissues (TT) in short-contact drop jumps (DJ) with three different drop heights [low (Low), optimal (OP), and high (High)] was examined with 11 subjects. The ground reaction force (F z) and ankle and knee joint angles were measured together with real-time ultrasonography (fascicle length) and electromyographic activities of the medial gastrocnemius (MG) and vastus lateralis (VL) muscles during the movement. With increasing drop height, the braking force and flight time increased from Low to OP ( P < 0.05). In High, the braking force increased but the flight time decreased compared with OP ( P < 0.05). During contact of Low and OP conditi…
Interrelationships between Muscle Structure, Muscle Strength, and Running Economy
2003
The present study was designed to investigate possible differences in running economy (RE) among elite middle-distance runners by examining muscle structure and maximal isometric force (MVC).Ten young male runners ran at six different running speeds. During the running bouts, respiratory gases, and blood lactate were measured. Muscle biopsies were obtained from the vastus lateralis muscle for analyzing fiber type distribution, muscle fiber area, myosin heavy chain (MHC) composition, activities of a number of metabolic enzymes (citrate synthase, lactate dehydrogenase, phosphofruktokinase, and 3-hydroxyacyl-CoA-dehydrogenase), and titin isoforms.Energy expenditure (EE) increased linearly up t…