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Sample records for muscle phosphocreatine kinetics

  1. Phosphocreatine kinetics at the onset of contractions in skeletal muscle of MM creatine kinase knockout mice

    Science.gov (United States)

    Roman, Brian B.; Meyer, Ronald A.; Wiseman, Robert W.

    2002-01-01

    Phosphocreatine (PCr) depletion during isometric twitch stimulation at 5 Hz was measured by (31)P-NMR spectroscopy in gastrocnemius muscles of pentobarbital-anesthetized MM creatine kinase knockout (MMKO) vs. wild-type C57B (WT) mice. PCr depletion after 2 s of stimulation, estimated from the difference between spectra gated to times 200 ms and 140 s after 2-s bursts of contractions, was 2.2 +/- 0.6% of initial PCr in MMKO muscle vs. 9.7 +/- 1.6% in WT muscles (mean +/- SE, n = 7, P muscle after 2 s only if ADP-stimulated oxidative phosphorylation was included in the model. Taken together, the results suggest that cytoplasmic ADP more rapidly increases and oxidative phosphorylation is more rapidly activated at the onset of contractions in MMKO compared with WT muscles.

  2. Intersubject differences in the effect of acidosis on phosphocreatine recovery kinetics in muscle after exercise are due to differences in proton efflux rates

    NARCIS (Netherlands)

    Broek, van den N.M.A.; Feyter, de H.M.M.L.; Graaf, de L.; Nicolay, K.; Prompers, J.J.

    2007-01-01

    31P magnetic resonance spectroscopy provides the possibility of obtaining bioenergetic data during skeletal muscle exercise and recovery. The time constant of phosphocreatine (PCr) recovery (tPCr) has been used as a measure of mitochondrial function. However, cytosolic pH has a strong influence on

  3. 31P MR spectroscopy and computational modeling identify a direct relation between Pi content of an alkaline compartment in resting muscle and phosphocreatine resynthesis kinetics in active muscle in humans.

    Directory of Open Access Journals (Sweden)

    Joep W M van Oorschot

    Full Text Available The assessment of mitochondrial properties in skeletal muscle is important in clinical research, for instance in the study of diabetes. The gold standard to measure mitochondrial capacity non-invasively is the phosphocreatine (PCr recovery rate after exercise, measured by (31P Magnetic Resonance spectroscopy ((31P MRS. Here, we sought to expand the evidence base for an alternative method to assess mitochondrial properties which uses (31P MRS measurement of the Pi content of an alkaline compartment attributed to mitochondria (Pi2; as opposed to cytosolic Pi (Pi1 in resting muscle at high magnetic field. Specifically, the PCr recovery rate in human quadriceps muscle was compared with the signal intensity of the Pi2 peak in subjects with varying mitochondrial content of the quadriceps muscle as a result of athletic training, and the results were entered into a mechanistic computational model of mitochondrial metabolism in muscle to test if the empirical relation between Pi2/Pi1 ratio and the PCr recovery was consistent with theory. Localized (31P spectra were obtained at 7T from resting vastus lateralis muscle to measure the intensity of the Pi2 peak. In the endurance trained athletes a Pi2/Pi1 ratio of 0.07 ± 0.01 was found, compared to a significantly lower (p<0.05 Pi2/Pi1 ratio of 0.03 ± 0.01 in the normally active group. Next, PCr recovery kinetics after in magnet bicycle exercise were measured at 1.5T. For the endurance trained athletes, a time constant τPCr 12 ± 3 s was found, compared to 24 ± 5s in normally active subjects. Without any parameter optimization the computational model prediction matched the experimental data well (r(2 of 0.75. Taken together, these results suggest that the Pi2 resonance in resting human skeletal muscle observed at 7T provides a quantitative MR-based functional measure of mitochondrial density.

  4. High-energy phosphate transfer in human muscle: diffusion of phosphocreatine.

    Science.gov (United States)

    Gabr, Refaat E; El-Sharkawy, Abdel-Monem M; Schär, Michael; Weiss, Robert G; Bottomley, Paul A

    2011-07-01

    The creatine kinase (CK) reaction is central to muscle energetics, buffering ATP levels during periods of intense activity via consumption of phosphocreatine (PCr). PCr is believed to serve as a spatial shuttle of high-energy phosphate between sites of energy production in the mitochondria and sites of energy utilization in the myofibrils via diffusion. Knowledge of the diffusion coefficient of PCr (D(PCr)) is thus critical for modeling and understanding energy transport in the myocyte, but D(PCr) has not been measured in humans. Using localized phosphorus magnetic resonance spectroscopy, we measured D(PCr) in the calf muscle of 11 adults as a function of direction and diffusion time. The results show that the diffusion of PCr is anisotropic, with significantly higher diffusion along the muscle fibers, and that the diffusion of PCr is restricted to a ∼28-μm pathlength assuming a cylindrical model, with an unbounded diffusion coefficient of ∼0.69 × 10(-3) mm(2)/s. This distance is comparable in size to the myofiber radius. On the basis of prior measures of CK reaction kinetics in human muscle, the expected diffusion distance of PCr during its half-life in the CK reaction is ∼66 μm. This distance is much greater than the average distances between mitochondria and myofibrils. Thus these first measurements of PCr diffusion in human muscle in vivo support the view that PCr diffusion is not a factor limiting high-energy phosphate transport between the mitochondria and the myofibrils in healthy resting myocytes.

  5. High-energy phosphate transfer in human muscle: diffusion of phosphocreatine

    OpenAIRE

    Gabr, Refaat E.; El-Sharkawy, AbdEl-Monem M.; Schär, Michael; Weiss, Robert G.; Bottomley, Paul A.

    2011-01-01

    The creatine kinase (CK) reaction is central to muscle energetics, buffering ATP levels during periods of intense activity via consumption of phosphocreatine (PCr). PCr is believed to serve as a spatial shuttle of high-energy phosphate between sites of energy production in the mitochondria and sites of energy utilization in the myofibrils via diffusion. Knowledge of the diffusion coefficient of PCr (DPCr) is thus critical for modeling and understanding energy transport in the myocyte, but DPC...

  6. ATP and phosphocreatine utilization in single human muscle fibres during the development of maximal power output at elevated muscle temperatures.

    Science.gov (United States)

    Gray, Stuart R; Söderlund, Karin; Ferguson, Richard A

    2008-05-01

    In this study, we examined the effect of muscle temperature (Tm) on adenosine triphosphate (ATP) and phosphocreatine utilization in single muscle fibres during the development of maximal power output in humans. Six male participants performed a 6-s maximal sprint on a friction-braked cycle ergometer under both normal (Tm = 34.3 degrees C, s = 0.6) and elevated (T(m) = 37.3 degrees C, s = 0.2) muscle temperature conditions. During the elevated condition, muscle temperature of the legs was raised, passively, by hot water immersion followed by wrapping in electrically heated blankets. Muscle biopsies were taken from the vastus lateralis before and immediately after exercise. Freeze-dried single fibres were dissected, characterized according to myosin heavy chain composition, and analysed for ATP and phosphocreatine content. Single fibres were classified as: type I, IIA, IIAX25 (1 - 25% IIX isoform), IIAX50 (26 - 50% IIX), IIAX75 (51 - 75% IIX), or IIAX100 (76 - 100% IIX). Maximal power output and pedal rate were both greater (P < 0.05) during the elevated condition by 258 W (s = 110) and 22 rev . min(-1) (s = 6), respectively. In both conditions, phosphocreatine content decreased significantly in all fibre types, with a greater decrease during the elevated condition in type IIA fibres (P < 0.01). Adenosine triphosphate content was also reduced to a greater (P < 0.01) extent in type IIA fibres during the elevated condition. The results of the present study indicate that after passive elevation of muscle temperature, there was a greater decrease in ATP and phosphocreatine content in type IIA fibres than in the normal trial, which contributed to the higher maximal power output.

  7. Comparison of in vivo postexercise phosphocreatine recovery and resting ATP synthesis flux for the assessment of skeletal muscle mitochondrial function

    NARCIS (Netherlands)

    Broek, van den N.M.A.; Ciapaite, J.; Nicolay, K.; Prompers, J.J.

    2010-01-01

    31P magnetic resonance spectroscopy (MRS) has been used to assess skeletal muscle mitochondrial function in vivo by measuring 1) phosphocreatine (PCr) recovery after exercise or 2) resting ATP synthesis flux with saturation transfer (ST). In this study, we compared both parameters in a rat model of

  8. Acetyl group availability influences phosphocreatine degradation even during intense muscle contraction.

    Science.gov (United States)

    Timmons, James A; Constantin-Teodosiu, Dumitru; Poucher, Simon M; Greenhaff, Paul L

    2004-12-15

    We previously established that activation of the pyruvate dehydrogenase complex (PDC) using dichloroacetate (DCA) reduced the reliance on substrate-level phosphorylation (SLP) at the onset of exercise, with normal and reduced blood flow. PDC activation also reduced fatigue development during contraction with reduced blood flow. Since these observations, several studies have re-evaluated our observations. One study demonstrated a performance benefit without a reduction in SLP, raising a question mark over PDC's role in the regulation of ATP regeneration and our interpretation of fatigue mechanisms. Using a model of muscle contraction similar to the conflicting study (i.e. tetanic rather than twitch stimulation), we re-examined this question. Using canine skeletal muscle, one group was infused with saline while the other was pretreated with 300 mg (kg body mass)(-1) DCA. Muscle biopsies were taken at rest, peak tension (1 min) and after 6 min of tetanic electrical stimulation (75 ms on-925 ms off per second) and blood flow was limited to 25% of normal values observed during contraction. DCA reduced phosphocreatine (PCr) degradation by 40% during the first minute of contraction, but did not prevent the almost complete depletion of PCr stores at 6 min, while muscle fatigue did not differ between the two groups. During intermittent tetanic stimulation PCr degradation was 75% greater than with our previous 3 Hz twitch contraction protocol, despite a similar rate of oxygen consumption at 6 min. Thus, in the present study enhanced acetyl group availability altered the time course of PCr utilization but did not prevent the decline towards depletion. Consistent with our earlier conclusions, DCA pretreatment reduces muscle fatigue only when SLP is attenuated. The present study and our met-analysis indicates that enhanced acetyl group availability results in a readily measurable reduction in SLP when the initial rate of PCr utilization is approximately 1 mmol (kg dry mass)(-1

  9. Creatine monohydrate supplementation does not increase muscle strength, lean body mass, or muscle phosphocreatine in patients with myotonic dystrophy type 1.

    Science.gov (United States)

    Tarnopolsky, Mark; Mahoney, Douglas; Thompson, Terry; Naylor, Heather; Doherty, Timothy J

    2004-01-01

    Creatine monohydrate (CrM) supplementation may increase strength in some types of muscular dystrophy. A recent study in myotonic muscular dystrophy type 1 (DM1) did not find a significant treatment effect, but measurements of muscle phosphocreatine (PCr) were not performed. We completed a randomized, double-blind, cross-over trial using 34 genetically confirmed adult DM1 patients without significant cognitive impairment. Participants received CrM (5 g, approximately 0.074 g/kg daily) and a placebo for each 4-month phase with a 6-week wash-out. Spirometry, manual muscle testing, quantitative isometric strength testing of handgrip, foot dorsiflexion, and knee extension, handgrip and foot dorsiflexion endurance, functional tasks, activity of daily living scales, body composition (total, bone, and fat-free mass), serum creatine kinase activity, serum creatinine concentration and clearance, and liver function tests were completed before and after each intervention, and muscle PCr/beta-adenosine triphosphate (ATP) ratios of the forearm flexor muscles were completed at the end of each phase. CrM supplementation did not increase any of the outcome measurements except for plasma creatinine concentration (but not creatinine clearance). Thus, CrM supplementation at 5 g daily does not have any effects on muscle strength, body composition, or activities of daily living in patients with DM1, perhaps because of a failure of the supplementation to increase muscle PCr/beta-ATP content.

  10. Phosphocreatine recovery overshoot after high intensity exercise in human skeletal muscle is associated with extensive muscle acidification and a significant decrease in phosphorylation potential.

    Science.gov (United States)

    Zoladz, Jerzy A; Korzeniewski, Bernard; Kulinowski, Piotr; Zapart-Bukowska, Justyna; Majerczak, Joanna; Jasiński, Andrzej

    2010-09-01

    The phosphocreatine (PCr) recovery overshoot in skeletal muscle is a transient increase of PCr concentration above the resting level after termination of exercise. In the present study [PCr], [ATP], [P(i)] and pH were measured in calf muscle during rest, during plantar flexion exercise until exhaustion and recovery, using the (31)P NMR spectroscopy. A significantly greater acidification of muscle cells and significantly lower phosphorylation potential (DeltaG (ATP)) at the end of exercise was encountered in the group of subjects that evidenced the [PCr] overshoot as well as [ADP] and [P(i)] undershoots than in the group that did not. We postulate that the role of the PCr overshoot-related transiently elevated [ATP]/[ADP(free)] ratio is to activate different processes (including protein synthesis) that participate in repairing numerous damages of the muscle cells caused by intensive exercise-induced stressing factors, such as extensive muscle acidification, a significant decrease in DeltaG (ATP), an elevated level of reactive oxygen species or mechanical disturbances.

  11. Relationship between serum IGF-1 and skeletal muscle IGF-1 mRNA expression to phosphocreatine recovery after exercise in obese men with reduced GH.

    Science.gov (United States)

    Hamarneh, Sulaiman R; Murphy, Caitlin A; Shih, Cynthia W; Frontera, Walter; Torriani, Martin; Irazoqui, Javier E; Makimura, Hideo

    2015-02-01

    GH and IGF-1 are believed to be physiological regulators of skeletal muscle mitochondria. The objective of this study was to examine the relationship between GH/IGF-1 and skeletal muscle mitochondria in obese subjects with reduced GH secretion in more detail. Fifteen abdominally obese men with reduced GH secretion were treated for 12 weeks with recombinant human GH. Subjects underwent (31)P-magnetic resonance spectroscopy to assess phosphocreatine (PCr) recovery as an in vivo measure of skeletal muscle mitochondrial function and percutaneous muscle biopsies to assess mRNA expression of IGF-1 and mitochondrial-related genes at baseline and 12 weeks. At baseline, skeletal muscle IGF-1 mRNA expression was significantly associated with PCr recovery (r = 0.79; P = .01) and nuclear respiratory factor-1 (r = 0.87; P = .001), mitochondrial transcription factor A (r = 0.86; P = .001), peroxisome proliferator-activated receptor (PPAR)γ (r = 0.72; P = .02), and PPARα (r = 0.75; P = .01) mRNA expression, and trended to an association with PPARγ coactivator 1-α (r = 0.59; P = .07) mRNA expression. However, serum IGF-1 concentration was not associated with PCr recovery or any mitochondrial gene expression (all P > .10). Administration of recombinant human GH increased both serum IGF-1 (change, 218 ± 29 μg/L; P IGF-1 mRNA in muscle (fold change, 2.1 ± 0.3; P = .002). Increases in serum IGF-1 were associated with improvements in total body fat (r = -0.53; P = .04), trunk fat (r = -0.55; P = .03), and lean mass (r = 0.58; P = .02), but not with PCr recovery (P > .10). Conversely, increase in muscle IGF-1 mRNA was associated with improvements in PCr recovery (r = 0.74; P = .02), but not with body composition parameters (P > .10). These data demonstrate a novel association of skeletal muscle mitochondria with muscle IGF-1 mRNA expression, but independent of serum IGF-1 concentrations.

  12. The role of pH on the thermodynamics and kinetics of muscle biochemistry: an in vivo study by (31)P-MRS in patients with myo-phosphorylase deficiency.

    Science.gov (United States)

    Malucelli, E; Iotti, S; Manners, D N; Testa, C; Martinuzzi, A; Barbiroli, B; Lodi, R

    2011-09-01

    In this study we assessed ΔG'(ATP) hydrolysis, cytosolic [ADP], and the rate of phosphocreatine recovery using Phosphorus Magnetic Resonance Spectroscopy in the calf muscle of a group of patients affected by glycogen myo-phosphorylase deficiency (McArdle disease). The goal was to ascertain whether and to what extent the deficit of the glycogenolytic pathway would affect the muscle energy balance. A typical feature of this pathology is the lack of intracellular acidosis. Therefore we posed the question of whether, in the absence of pH decrease, the rate of phosphocreatine recovery depends on the amount of phosphocreatine consumed during exercise. Results showed that at the end of exercise both [ADP] and ΔG'(ATP) of patients were significantly higher than those of matched control groups reaching comparable levels of phosphocreatine concentration. Furthermore, in these patients we found that the rate of phosphocreatine recovery is not influenced by the amount of phosphocreatine consumed during exercise. These outcomes provide experimental evidence that: i) the intracellular acidification occurring in exercising skeletal muscle is a protective factor for the energy consumption; and ii) the influence of pH on the phosphocreatine recovery rate is at least in part related to the kinetic mechanisms of mitochondrial creatine kinase enzyme. 2011 Elsevier B.V. All rights reserved.

  13. Functional coupling of glycolysis and phosphocreatine utilization in anoxic fish muscle. : An in vivo 31P NMR study

    NARCIS (Netherlands)

    Van Waarde, A; Van den Thillart, G; Erkelens, Cees; Addink, A; Lugtenburg, J

    1990-01-01

    Three fish species with different strategies for anoxic survival (goldfish, tilapia, and common carp) were exposed to environmental anoxia (4, 3, and 1 h, respectively). The concentrations of high energy phosphate compounds and inorganic phosphate, besides the intracellular pH in the epaxial muscle

  14. Slow VO2 off-kinetics in skeletal muscle is associated with fast PCr off-kinetics--and inversely.

    Science.gov (United States)

    Korzeniewski, Bernard; Zoladz, Jerzy A

    2013-09-01

    The computer model of the bioenergetic system in skeletal muscle, developed previously, was used to study the effect of the characteristic decay time of the parallel activation of oxidative phosphorylation [τ(OFF)] during muscle recovery on the muscle oxygen consumption rate (Vo2) and phosphocreatine (PCr) work-to-rest transition (off)-kinetics and on the relationship between the Vo2 and PCr rest-to-work transition (on)- and off-kinetics in moderate and heavy exercise. An increase in τ(OFF) slows down the initial phase of the muscle Vo2 off-kinetics and accelerates the PCr off-kinetics. As a result, the relationship between the initial phase of the Vo2 off-kinetics (lasting approximately 3-60 s in computer simulations) and the PCr off-kinetics is inverse: the slower the former, the faster the latter. A faster initial phase of the Vo2 off-kinetics is associated with a slower late phase of the Vo2 off-kinetics, and as a result, the integral of Vo2 above baseline during recovery, representing the oxygen debt, is identical in all cases [values of τ(OFF)] for a given PCr decrease. Depending on τ(OFF), the muscle Vo2 on-kinetics was either equally fast or slower than the Vo2 off-kinetics in moderate exercise and always slower in heavy exercise. PCr on-kinetics was always faster than PCr off-kinetics. This study clearly demonstrates that τ(OFF) has a pronounced impact on the mutual relations between the muscle Vo2 and PCr on- and off-kinetics.

  15. Increased recovery rates of phosphocreatine and inorganic phosphate after isometric contraction in oxidative muscle fibres and elevated hepatic insulin resistance in homozygous carriers of the A-allele of FTO rs9939609

    DEFF Research Database (Denmark)

    Grunnet, Louise Groth; Brøns, Charlotte; Jacobsen, Stine

    2009-01-01

    9939609 A-allele was associated with elevated fasting blood glucose and plasma insulin, hepatic insulin resistance and shorter recovery halftimes of phosphocreatine (PCr) and inorganic phosphate (Pi) after exercise in a primarily type I muscle. These relationships - except for fasting insulin - remained...... or mitochondrially encoded genes in skeletal muscle during rest. Conclusion. Increased energy efficiency - and potentially increased mitochondrial coupling - as suggested by faster recovery rates of PCr and Pi in oxidative muscle fibres may contribute to the increased risk of obesity and type 2 diabetes...

  16. Biochemical background of the VO2 on-kinetics in skeletal muscles.

    Science.gov (United States)

    Korzeniewski, Bernard; Zoladz, Jerzy A

    2006-02-01

    This review discusses the present knowledge on the oxygen uptake kinetics at the onset of exercise in skeletal muscle and the contribution of a previously developed computer model of oxidative phosphorylation in intact skeletal muscle to the understanding of the factors determining this kinetics on the biochemical level. It has been demonstrated recently that an increase in the total creatine pool [PCr + Cr] and in glycolytic ATP supply lengthen the half-transition time of the VO2 on-kinetics, while an increase in mitochondria content, in parallel activation of ATP supply and ATP usage, in muscle oxygen concentration, in proton leak, in resting energy demand, in resting cytosolic pH, and in initial alkalization diminish this parameter. It has also been shown that the half-transition time is near-linearly proportional to the absolute difference between the phosphocreatine concentration during work and at rest (deltaPCr). The present review discusses whether the V/O2 on-kinetics on the muscle level is strictly or only approximately exponential. Finally, it is postulated that a short transition time of the VO2 on-kinetics in itself does not need be profitable for the skeletal muscle functioning during exercise, but usually a short transition time is correlated with factors that improve exercise capacity. The transition time is a phenomenological parameter resulting from the biochemical properties of the system and not a physical factor that can cause anything in the system.

  17. Possible mechanisms underlying slow component of V̇O2 on-kinetics in skeletal muscle.

    Science.gov (United States)

    Korzeniewski, Bernard; Zoladz, Jerzy A

    2015-05-15

    A computer model of a skeletal muscle bioenergetic system is used to study the background of the slow component of oxygen consumption V̇O2 on-kinetics in skeletal muscle. Two possible mechanisms are analyzed: inhibition of ATP production by anaerobic glycolysis by progressive cytosol acidification (together with a slow decrease in ATP supply by creatine kinase) and gradual increase of ATP usage during exercise of constant power output. It is demonstrated that the former novel mechanism is potent to generate the slow component. The latter mechanism further increases the size of the slow component; it also moderately decreases metabolite stability and has a small impact on muscle pH. An increase in anaerobic glycolysis intensity increases the slow component, elevates cytosol acidification during exercise, and decreases phosphocreatine and Pi stability, although slightly increases ADP stability. A decrease in the P/O ratio (ATP molecules/O2 molecules) during exercise cannot also be excluded as a relevant mechanism, although this issue requires further study. It is postulated that both the progressive inhibition of anaerobic glycolysis by accumulating protons (together with a slow decrease of the net creatine kinase reaction rate) and gradual increase of ATP usage during exercise, and perhaps a decrease in P/O, contribute to the generation of the slow component of the V̇O2 on-kinetics in skeletal muscle. Copyright © 2015 the American Physiological Society.

  18. Kinetics of glucose transport in rat muscle

    DEFF Research Database (Denmark)

    Ploug, Thorkil; Galbo, Henrik; Vinten, Jørgen

    1987-01-01

    The effects of insulin and prior muscle contractions, respectively, on 3-O-methylglucose (3-O-MG) transport in skeletal muscle were studied in the perfused rat hindquarter. Initial rates of entry of 3-O-MG in red gastrocnemius, soleus, and white gastrocnemius muscles as a function of perfusate 3-O-MG...... concentration exhibited Michaelis-Menten kinetics. Uptake by simple diffusion could not be detected. The maximum 3-O-MG transport velocity (Vmax) was increased more by maximum isometric contractions (10- to 40-fold, depending on fiber type) than by insulin (20,000 microU/ml; 3- to 20-fold) in both red and white...

  19. Factors determining the oxygen consumption rate (VO2) on-kinetics in skeletal muscles.

    Science.gov (United States)

    Korzeniewski, Bernard; Zoladz, Jerzy A

    2004-05-01

    Using a computer model of oxidative phosphorylation developed previously [Korzeniewski and Mazat (1996) Biochem. J. 319, 143-148; Korzeniewski and Zoladz (2001) Biophys. Chem. 92, 17-34], we analyse the effect of several factors on the oxygen-uptake kinetics, especially on the oxygen consumption rate (VO2) and half-transition time t(1/2), at the onset of exercise in skeletal muscles. Computer simulations demonstrate that an increase in the total creatine pool [PCr+/-Cr] (where Cr stands for creatine and PCr for phosphocreatine) and in glycolytic ATP supply lengthen the half-transition time, whereas increase in mitochondrial content, in parallel activation of ATP supply and ATP usage, in oxygen concentration, in proton leak, in resting energy demand, in resting cytosolic pH and in initial alkalization decrease this parameter. Theoretical studies show that a decrease in the activity of creatine kinase (CK) [displacement of this enzyme from equilibrium during on-transient (rest-to-work transition)] accelerates the first stage of the VO2 on-transient, but slows down the second stage of this transient. It is also demonstrated that a prior exercise terminated a few minutes before the principal exercise shortens the transition time. Finally, it is shown that at a given ATP demand, and under conditions where CK works near the thermodynamic equilibrium, the half-transition time of VO2 kinetics is determined by the amount of PCr that has to be transformed into Cr during rest-to-work transition; therefore any factor that diminishes the difference in [PCr] between rest and work at a given energy demand will accelerate the VO2 on-kinetics. Our conclusions agree with the general idea formulated originally by Easterby [(1981) Biochem. J. 199, 155-161] that changes in metabolite concentrations determine the transition times between different steady states in metabolic systems.

  20. Substrate kinetics in patients with disorders of skeletal muscle metabolism.

    Science.gov (United States)

    Ørngreen, Mette Cathrine

    2016-07-01

    The main purpose of the following studies was to investigate pathophysiological mechanisms in fat and carbohydrate metabolism and effect of nutritional interventions in patients with metabolic myopathies and in patients with severe muscle wasting. Yet there is no cure for patients with skeletal muscle disorders. The group of patients is heterozygous and this thesis is focused on patients with metabolic myopathies and low muscle mass due to severe muscle wasting. Disorders of fatty acid oxidation (FAO) are, along with myophosphorylase deficiency (McArdle disease), the most common inborn errors of metabolism leading to recurrent episodes of rhabdomyolysis in adults. Prolonged exercise, fasting, and fever are the main triggering factors for rhabdomyolysis in these conditions, and can be complicated by acute renal failure. Patients with low muscle mass are in risk of loosing their functional skills and depend on a wheel chair and respiratory support. We used nutritional interventions and metabolic studies with stable isotope technique and indirect calorimetry in patients with metabolic myopathies and patients with low muscle mass to get information of the metabolism of the investigated diseases, and to gain knowledge of the biochemical pathways of intermediary metabolism in human skeletal muscle. We have shown that patients with fat metabolism disorders in skeletal muscle affecting the transporting enzyme of fat into the mitochondria (carnitine palmitoyltransferase II deficiency) and affecting the enzyme responsible for breakdown of the long-chain fatty acids (very long chain acyl-CoA dehydrogenase deficiency) have a normal fatty acid oxidation at rest, but enzyme activity is too low to increase fatty acid oxidation during exercise. Furthermore, these patients benefit from a carbohydrate rich diet. Oppositely is exercise capacity worsened by a fat-rich diet in these patients. The patients also benefit from IV glucose, however, when glucose is given orally just before

  1. Immobilization of cardioprotective drug phosphocreatine on a surface of nanoparticles of silica

    Science.gov (United States)

    Korolev, D. V.; Evreinova, N. V.; Zakharova, E. V.; Gareev, K. G.; Naumysheva, E. B.; Postnov, V. N.; Galagudza, M. M.

    2017-11-01

    In this work silica aminated nanoparticles were used to show capability for chemisorbing organic compound having a carboxyl group. Phosphocreatine (creatine phosphate) was used as an active ingredient. Since the method for determination of phosphocreatine with the sample analysis using Jaffe reaction didn’t give a positive result, the definition of free phosphocreatine was carried out by the method of diacetyl in the presence of α-naphthol.

  2. Progressive recruitment of muscle fibers is not necessary for the slow component of VO2 kinetics.

    Science.gov (United States)

    Zoladz, Jerzy A; Gladden, L Bruce; Hogan, Michael C; Nieckarz, Zenon; Grassi, Bruno

    2008-08-01

    The "slow component" of O2 uptake (VO2) kinetics during constant-load heavy-intensity exercise is traditionally thought to derive from a progressive recruitment of muscle fibers. In this study, which represents a reanalysis of data taken from a previous study by our group (Grassi B, Hogan MC, Greenhaff PL, Hamann JJ, Kelley KM, Aschenbach WG, Constantin-Teodosiu D, Gladden LB. J Physiol 538: 195-207, 2002) we evaluated the presence of a slow component-like response in the isolated dog gastrocnemius in situ (n=6) during 4 min of contractions at approximately 60-70% of peak VO2. In this preparation all muscle fibers are maximally activated by electrical stimulation from the beginning of the contraction period, and no progressive recruitment of fibers is possible. Muscle VO2 was calculated as blood flow multiplied by arteriovenous O2 content difference. The muscle fatigued (force decreased by approximately 20-25%) during contractions. Kinetics of adjustment were evaluated for 1) VO2, uncorrected for force development; 2) VO2 normalized for peak force; 3) VO2 normalized for force-time integral. A slow component-like response, described in only one muscle out of six when uncorrected VO2 was considered, was observed in all muscles when VO2/peak force and VO2/force-time were considered. The amplitude of the slow component-like response, expressed as a fraction of the total response, was higher for VO2/peak force (0.18+/-0.06, means+/-SE) and for VO2/force-time (0.22+/-0.05) compared with uncorrected VO2 (0.04+/-0.04). A progressive recruitment of muscle fibers may not be necessary for the development of the slow component of VO2 kinetics, which may be caused by the metabolic factors that induce muscle fatigue and, as a consequence, reduce the efficiency of muscle contractions.

  3. Kinetics of contraction-induced GLUT4 translocation in skeletal muscle fibers from living mice

    DEFF Research Database (Denmark)

    Lauritzen, Hans Peter M. Mortensen; Galbo, Henrik; Toyoda, Taro

    2010-01-01

    Exercise is an important strategy for the treatment of type 2 diabetes. This is due in part to an increase in glucose transport that occurs in the working skeletal muscles. Glucose transport is regulated by GLUT4 translocation in muscle, but the molecular machinery mediating this process is poorly...... understood. The purpose of this study was to 1) use a novel imaging system to elucidate the kinetics of contraction-induced GLUT4 translocation in skeletal muscle and 2) determine the function of AMP-activated protein kinase alpha2 (AMPKalpha2) in this process....

  4. Kinetics of contraction-induced GLUT4 translocation in skeletal muscle fibers from living mice

    DEFF Research Database (Denmark)

    Lauritzen, Hans Peter M. Mortensen; Galbo, Henrik; Toyoda, Taro

    2010-01-01

    Exercise is an important strategy for the treatment of type 2 diabetes. This is due in part to an increase in glucose transport that occurs in the working skeletal muscles. Glucose transport is regulated by GLUT4 translocation in muscle, but the molecular machinery mediating this process is poorl...... understood. The purpose of this study was to 1) use a novel imaging system to elucidate the kinetics of contraction-induced GLUT4 translocation in skeletal muscle and 2) determine the function of AMP-activated protein kinase alpha2 (AMPKalpha2) in this process.......Exercise is an important strategy for the treatment of type 2 diabetes. This is due in part to an increase in glucose transport that occurs in the working skeletal muscles. Glucose transport is regulated by GLUT4 translocation in muscle, but the molecular machinery mediating this process is poorly...

  5. The Kinetics of Myosin Light Chain Kinase Activation of Smooth Muscle Myosin in an In Vitro Model System

    OpenAIRE

    Hong, Feng; Facemyer, Kevin C.; Carter, Michael S.; Jackson, Del R.; Haldeman, Brian D.; Ruana, Nick; Sutherland, Cindy; Walsh, Michael P.; Cremo, Christine R.; Baker, Josh E.

    2013-01-01

    During activation of smooth muscle contraction, one myosin light chain kinase (MLCK) molecule rapidly phosphorylates many smooth muscle myosin (SMM) molecules, suggesting that muscle activation rates are influenced by the kinetics of MLCK-SMM interactions. To determine the rate-limiting step underlying activation of SMM by MLCK, we measured the kinetics of calcium-calmodulin (Ca2+-CaM)-MLCK-mediated SMM phosphorylation and the corresponding initiation of SMM-based F-actin motility in an in vi...

  6. Training-induced acceleration of oxygen uptake kinetics in skeletal muscle: the underlying mechanisms.

    Science.gov (United States)

    Zoladz, J A; Korzeniewski, B; Grassi, B

    2006-11-01

    It is well known that the oxygen uptake kinetics during rest-to-work transition (V(O2) on-kinetics) in trained subjects is significantly faster than in untrained individuals. It was recently postulated that the main system variable that determines the transition time (t(1/2)) of the V(O2) on-kinetics in skeletal muscle, at a given moderate ATP usage/work intensity, and under the assumption that creatine kinase reaction works near thermodynamic equilibrium, is the absolute (in mM) decrease in [PCr] during rest-to-work transition. Therefore we postulate that the training-induced acceleration of the V(O2) on-kinetics is a marker of an improvement of absolute metabolic stability in skeletal muscles. The most frequently postulated factor responsible for enhancement of muscle metabolic stability is the training-induced increase in mitochondrial proteins. However, the mechanism proposed by Gollnick and Saltin (1982) can improve absolute metabolic stability only if training leads to a decrease in resting [ADP(free)]. This effect is not observed in many examples of training causing an acceleration of the V(O2) on-kinetics, especially in early stages of training. Additionally, this mechanism cannot account for the significant training-induced increase in the relative (expressed in % or as multiples of the resting values) metabolic stability at low work intensities, condition in which oxidative phosphorylation is not saturated with [ADP(free)]. Finally, it was reported that in the early stage of training, acceleration in the V(O2) on-kinetics and enhancement of muscle metabolic stability may precede adaptive responses in mitochondrial enzymes activities or mitochondria content. We postulate that the training-induced acceleration in the V(O2) on-kinetics and the improvement of the metabolite stability during moderate intensity exercise in the early stage of training is mostly caused by an intensification of the "parallel activation" of ATP consumption and ATP supply pathways

  7. Muscle interstitial potassium kinetics during intense exhaustive exercise

    DEFF Research Database (Denmark)

    Nordsborg, Nikolai; Mohr, Magni; Pedersen, Lasse Dannemann

    2003-01-01

    Interstitial K+ ([K+]i) was measured in human skeletal muscle by microdialysis during exhaustive leg exercise, with (AL) and without (L) previous intense arm exercise. In addition, the reproducibility of the [K+]i determinations was examined. Possible microdialysis-induced rupture of the sarcolemma...... was assessed by measurement of carnosine in the dialysate, because carnosine is only expected to be found intracellularly. Changes in [K+]i could be reproduced, when exhaustive leg exercise was performed on two different days, with a between-day difference of approximately 0.5 mM at rest and 1.5 m......M at exhaustion. The time to exhaustion was shorter in AL than in L (2.7 +/- 0.3 vs. 4.0 +/- 0.3 min; P exercise period in AL compared with L (9.2 +/- 0.7 vs. 6.4 +/- 0.9 mM; P

  8. Influence of exercise intensity on skeletal muscle blood flow, O2 extraction and O2 uptake on-kinetics

    DEFF Research Database (Denmark)

    Jones, Andrew M; Krustrup, Peter; Wilkerson, Daryl P

    2012-01-01

    Key points Following the start of low-intensity exercise in healthy humans, it has been established that the kinetics of muscle O(2) delivery is faster than, and does not limit, the kinetics of muscle O(2) uptake. Direct data are lacking, however, on the question of whether O(2) delivery might...... limit O(2) uptake kinetics during high-intensity exercise. In this study, we made frequent measurements of muscle blood flow, arterial-to-venous O(2) difference (a- difference) and O(2) uptake following the onset of multiple transitions of both low-intensity and high-intensity knee-extension exercise...... in the same subjects. We show that although blood flow kinetics is slower for high-intensity compared with low-intensity exercise, this does not result in slower O(2) uptake kinetics. These results indicate that muscle O(2) delivery does not limit O(2) uptake during knee-extension exercise in healthy humans....

  9. Locomotor muscle fatigue does not alter oxygen uptake kinetics during high-intensity exercise

    Directory of Open Access Journals (Sweden)

    James Hopker

    2016-10-01

    Full Text Available The slow component (VO2sc that develops during high-intensity aerobic exercise is thought to be strongly associated with locomotor muscle fatigue. We sought to experimentally test this hypothesis by pre-fatiguing the locomotor muscles used during subsequent high-intensity cycling exercise. Over two separate visits, eight healthy male participants were asked to either perform a non-metabolically stressful 100 intermittent drop-jumps protocol (pre fatigue condition or rest for 33 minutes (control condition according to a random and counterbalanced order. Locomotor muscle fatigue was quantified with 6-second maximal sprints at a fixed pedaling cadence of 90 rev·min-1. Oxygen kinetics and other responses (heart rate, capillary blood lactate concentration and rating of perceived exertion, RPE were measured during two subsequent bouts of 6 min cycling exercise at 50% of the delta between the lactate threshold and VO2max determined during a preliminary incremental exercise test. All tests were performed on the same cycle ergometer. Despite significant locomotor muscle fatigue (P = 0.03, the VO2sc was not significantly different between the pre fatigue (464 ± 301 mL·min-1 and the control (556 ± 223 mL·min-1 condition (P = 0.50. Blood lactate response was not significantly different between conditions (P = 0.48 but RPE was significantly higher following the pre-fatiguing exercise protocol compared with the control condition (P < 0.01 suggesting higher muscle recruitment. These results demonstrate experimentally that locomotor muscle fatigue does not significantly alter the VO2 kinetic response to high intensity aerobic exercise, and challenge the hypothesis that the VO2sc is strongly associated with locomotor muscle fatigue.

  10. Locomotor Muscle Fatigue Does Not Alter Oxygen Uptake Kinetics during High-Intensity Exercise.

    Science.gov (United States)

    Hopker, James G; Caporaso, Giuseppe; Azzalin, Andrea; Carpenter, Roger; Marcora, Samuele M

    2016-01-01

    The [Formula: see text] slow component ([Formula: see text]) that develops during high-intensity aerobic exercise is thought to be strongly associated with locomotor muscle fatigue. We sought to experimentally test this hypothesis by pre-fatiguing the locomotor muscles used during subsequent high-intensity cycling exercise. Over two separate visits, eight healthy male participants were asked to either perform a non-metabolically stressful 100 intermittent drop-jumps protocol (pre-fatigue condition) or rest for 33 min (control condition) according to a random and counterbalanced order. Locomotor muscle fatigue was quantified with 6-s maximal sprints at a fixed pedaling cadence of 90 rev·min -1 . Oxygen kinetics and other responses (heart rate, capillary blood lactate concentration and rating of perceived exertion, RPE) were measured during two subsequent bouts of 6 min cycling exercise at 50% of the delta between the lactate threshold and [Formula: see text] determined during a preliminary incremental exercise test. All tests were performed on the same cycle ergometer. Despite significant locomotor muscle fatigue ( P = 0.03), the [Formula: see text] was not significantly different between the pre-fatigue (464 ± 301 mL·min -1 ) and the control (556 ± 223 mL·min -1 ) condition ( P = 0.50). Blood lactate response was not significantly different between conditions ( P = 0.48) but RPE was significantly higher following the pre-fatiguing exercise protocol compared with the control condition ( P locomotor muscle fatigue does not significantly alter the [Formula: see text] kinetic response to high intensity aerobic exercise, and challenge the hypothesis that the [Formula: see text] is strongly associated with locomotor muscle fatigue.

  11. Rat muscle microvascular PO2 kinetics during the exercise off-transient.

    Science.gov (United States)

    McDonough, P; Behnke, B J; Kindig, C A; Poole, D C

    2001-05-01

    Dependent upon the relative speed of pulmonary oxygen consumption (VO2) and blood flow (Q) kinetics, the exercise off-transient may represent a condition of sub- or supra-optimal perfusion. To date, there are no direct measurements of the dynamics of the VO2/Q relationship within the muscle at the onset of the work/recovery transition. To address this issue, microvascular PO2 (PO2,m) dynamics were studied in the spinotrapezius muscles of 11 female Sprague-Dawley rats (weight approximately 220 g) during and following electrical stimulation (1 Hz) to assess the adequacy of Q. relative to VO2 post exercise. The exercise blood flow response (radioactive microspheres: muscle Q increased approximately 240 %), and post-exercise arterial blood pH (7.40 +/- 0.02) and blood lactate (1.3 +/- 0.4 mM x l(-1)) values were consistent with moderate-intensity exercise. Recovery PO2,m (i.e. off-transient) rose progressively until baseline values were achieved ((Delta)end-recovery exercise PO2,m, 14.0 +/- 1.9 Torr) and at no time fell below exercising PO2,m. The off-transient PO2,m was well fitted by a dual exponential model with both fast (tau = 25.4 +/- 5.1 s) and slow (tau = 71.2 +/- 34.2 s) components. Furthermore, there was a pronounced delay (54.9 +/- 10.7 s) before the onset of the slow component. These data, obtained at the muscle microvascular level, support the notion that muscle VO2 falls with faster kinetics than muscle Q during the off-transient, such that PO2,m increases systematically, though biphasically, during recovery.

  12. Factors determining the oxygen consumption rate (VO2) on-kinetics in skeletal muscles.

    OpenAIRE

    Korzeniewski, Bernard; Zoladz, Jerzy A

    2004-01-01

    Using a computer model of oxidative phosphorylation developed previously [Korzeniewski and Mazat (1996) Biochem. J. 319, 143-148; Korzeniewski and Zoladz (2001) Biophys. Chem. 92, 17-34], we analyse the effect of several factors on the oxygen-uptake kinetics, especially on the oxygen consumption rate (VO2) and half-transition time t(1/2), at the onset of exercise in skeletal muscles. Computer simulations demonstrate that an increase in the total creatine pool [PCr+/-Cr] (where Cr stands for c...

  13. Change in concentration of inorganic phosphate and phosphocreatine in the rat diaphragm under the influence of whole-body gamma irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Mansour, M A; Gaber, M; Abdel-Fatah, K I

    1987-01-01

    The influence of irradiation on the concentration of creatine phosphate and inorganic phosphate in the diaphragm muscle were studied in rats exposed to 400 rad and 800 rad whole-body gamma radiation. The results showed that on the first day of post-exposure with 400 rad, the creatine phosphate concentration significantly increased, while the level significantly decreased on the third up to the fourteenth days of post exposure. In animals exposed to 800 rad, the diaphragm phosphocreatine showed a significant decrease on the first up to the ninth day post-irradiation as compared with the control group.

  14. Change in concentration of inorganic phosphate and phosphocreatine in the rat diaphragm under the influence of whole-body gamma irradiation

    International Nuclear Information System (INIS)

    Mansour, M.A.; Gaber, M.; Abdel-Fatah, K.I.

    1987-01-01

    The influence of irradiation on the concentration of creatine phosphate and inorganic phosphate in the diaphragm muscle were studied in rats exposed to 400 rad and 800 rad whole-body gamma radiation. The results showed that on the first day of post-exposure with 400 rad, the creatine phosphate concentration significantly increased, while the level significantly decreased on the third up to the fourteenth days of post exposure. In animals exposed to 800 rad, the diaphragm phosphocreatine showed a significant decrease on the first up to the ninth day post-irradiation as compared with the control group

  15. Association between isometric muscle strength and gait joint kinetics in adolescents and young adults with cerebral palsy.

    Science.gov (United States)

    Dallmeijer, A J; Baker, R; Dodd, K J; Taylor, N F

    2011-03-01

    The purpose of this study was to determine the association between isometric muscle strength of the lower limbs and gait joint kinetics in adolescents and young adults with cerebral palsy (CP). Twenty-five participants (11 males) with bilateral spastic CP, aged 14-22 years (mean: 18.9, sd: 2.0 yr) and Gross Motor Function Classification System (GMFCS) level II (n=19) and III (n=6) were tested. Hand held dynamometry was used to measure isometric strength (expressed in Nm/kg) of the hip, knee, and ankle muscles using standardized testing positions and procedures. 3D gait analysis was performed with a VICON system to calculate joint kinetics in the hip, knee and ankle during gait. Ankle peak moments exceeded by far the levels of isometric strength of the plantar flexors, while the knee and hip peak moments were just at or below maximal isometric strength of knee and hip muscles. Isometric muscle strength showed weak to moderate correlations with peak ankle and hip extension moment and power during walking. Despite considerable muscle weakness, joint moment curves were similar to norm values. Results suggest that passive stretch of the muscle-tendon complex of the triceps surae contributes to the ankle moment during walking and that muscle strength assessment may provide additional information to gait kinetics. Copyright © 2010 Elsevier B.V. All rights reserved.

  16. Influence of exercise intensity on skeletal muscle blood flow, O2 extraction and O2 uptake on-kinetics

    Science.gov (United States)

    Jones, Andrew M; Krustrup, Peter; Wilkerson, Daryl P; Berger, Nicolas J; Calbet, José A; Bangsbo, Jens

    2012-01-01

    Following the start of low-intensity exercise in healthy humans, it has been established that the kinetics of skeletal muscle O2 delivery is faster than, and does not limit, the kinetics of muscle O2 uptake (). Direct data are lacking, however, on the question of whether O2 delivery might limit kinetics during high-intensity exercise. Using multiple exercise transitions to enhance confidence in parameter estimation, we therefore investigated the kinetics of, and inter-relationships between, muscle blood flow (), a– difference and following the onset of low-intensity (LI) and high-intensity (HI) exercise. Seven healthy males completed four 6 min bouts of LI and four 6 min bouts of HI single-legged knee-extension exercise. Blood was frequently drawn from the femoral artery and vein during exercise and , a– difference and were calculated and subsequently modelled using non-linear regression techniques. For LI, the fundamental component mean response time (MRTp) for kinetics was significantly shorter than kinetics (mean ± SEM, 18 ± 4 vs. 30 ± 4 s; P exercise intensities; however, the MRTp for a– difference was significantly shorter for HI compared with LI (17 ± 3 vs. 28 ± 4 s; P exercise and remained unaltered thereafter, with no differences between LI and HI. These results indicate that bulk O2 delivery does not limit kinetics following the onset of LI or HI knee-extension exercise. PMID:22711961

  17. Relationship between gluteal muscle activation and upper extremity kinematics and kinetics in softball position players.

    Science.gov (United States)

    Oliver, Gretchen D

    2014-03-01

    As the biomechanical literature concerning softball pitching is evolving, there are no data to support the mechanics of softball position players. Pitching literature supports the whole kinetic chain approach including the lower extremity in proper throwing mechanics. The purpose of this project was to examine the gluteal muscle group activation patterns and their relationship with shoulder and elbow kinematics and kinetics during the overhead throwing motion of softball position players. Eighteen Division I National Collegiate Athletic Association softball players (19.2 ± 1.0 years; 68.9 ± 8.7 kg; 168.6 ± 6.6 cm) who were listed on the active playing roster volunteered. Electromyographic, kinematic, and kinetic data were collected while players caught a simulated hit or pitched ball and perform their position throw. Pearson correlation revealed a significant negative correlation between non-throwing gluteus maximus during the phase of maximum external rotation to maximum internal rotation (MIR) and elbow moments at ball release (r = -0.52). While at ball release, trunk flexion and rotation both had a positive relationship with shoulder moments at MIR (r = 0.69, r = 0.82, respectively) suggesting that the kinematic actions of the pelvis and trunk are strongly related to the actions of the shoulder during throwing.

  18. A short period of high-intensity interval training improves skeletal muscle mitochondrial function and pulmonary oxygen uptake kinetics

    DEFF Research Database (Denmark)

    Christensen, Peter Møller; Jacobs, Robert A; Bonne, Thomas Christian

    2016-01-01

    The aim of the present study was to examine whether improvements in pulmonary V̇O2 kinetics following a short period of high-intensity training (HIT) would be associated with improved skeletal muscle mitochondrial function. Ten untrained male volunteers (age: 26 ± 2; mean ± SD) performed six HIT...

  19. Association between isometric muscle strength and gait joint kinetics in adolescents and young adults with cerebral palsy

    NARCIS (Netherlands)

    Dallmeijer, A.J.; Baker, R.; Dodd, K.; Taylor, N.

    2011-01-01

    The purpose of this study was to determine the association between isometric muscle strength of the lower limbs and gait joint kinetics in adolescents and young adults with cerebral palsy (CP). Twenty-five participants (11 males) with bilateral spastic CP, aged 14-22 years (mean: 18.9, sd: 2.0. yr)

  20. Effect of intensified training on muscle ion kinetics, fatigue development and repeated short term performance in endurance trained cyclists

    DEFF Research Database (Denmark)

    Gunnarsson, Thomas Gunnar Petursson; Christensen, Peter Møller; Thomassen, Martin

    2013-01-01

    The effects of intensified training in combination with a reduced training volume on muscle ion kinetics, transporters and work capacity were examined. Eight well-trained cyclists replaced their regular training with speed-endurance training (12x30-s sprints) 2-3 times per wk and aerobic high...

  1. Role of glycogen availability in sarcoplasmic reticulum Ca2+ kinetics in human skeletal muscle

    DEFF Research Database (Denmark)

    Ørtenblad, Niels; Nielsen, Joachim; Saltin, Bengt

    2011-01-01

    Glucose is stored as glycogen in skeletal muscle. The importance of glycogen as a fuel during exercise has been recognized since the 1960s; however, little is known about the precise mechanism that relates skeletal muscle glycogen to muscle fatigue. We show that low muscle glycogen is associated...... with an impairment of muscle ability to release Ca(2+), which is an important signal in the muscle activation. Thus, depletion of glycogen during prolonged, exhausting exercise may contribute to muscle fatigue by causing decreased Ca(2+) release inside the muscle. These data provide indications of a signal...

  2. Electrostimulation improves muscle perfusion but does not affect either muscle deoxygenation or pulmonary oxygen consumption kinetics during a heavy constant-load exercise.

    Science.gov (United States)

    Layec, Gwenael; Millet, Grégoire P; Jougla, Aurélie; Micallef, Jean-Paul; Bendahan, David

    2008-02-01

    Electromyostimulation (EMS) is commonly used as part of training programs. However, the exact effects at the muscle level are largely unknown and it has been recently hypothesized that the beneficial effect of EMS could be mediated by an improved muscle perfusion. In the present study, we investigated rates of changes in pulmonary oxygen consumption (VO(2p)) and muscle deoxygenation during a standardized exercise performed after an EMS warm-up session. We aimed at determining whether EMS could modify pulmonary O(2) uptake and muscle deoxygenation as a result of improved oxygen delivery. Nine subjects performed a 6-min heavy constant load cycling exercise bout preceded either by an EMS session (EMS) or under control conditions (CONT). VO(2p) and heart rate (HR) were measured while deoxy-(HHb), oxy-(HbO(2)) and total haemoglobin/myoglobin (Hb(tot)) relative contents were measured using near infrared spectroscopy. EMS significantly increased (P < 0.05) the Hb(tot) resting level illustrating a residual hyperaemia. The EMS priming exercise did not affect either the HHb time constant (17.7 +/- 14.2 s vs. 13.1 +/- 2.3 s under control conditions) or the VO(2p) kinetics (time-constant = 18.2 +/- 5.2 s vs. 15.4 +/- 4.6 s under control conditions). Likewise, the other VO(2p) parameters were unchanged. Our results further indicated that EMS warm-up improved muscle perfusion through a residual hyperaemia. However, neither VO(2p) nor [HHb] kinetics were modified accordingly. These results suggest that improved O(2) delivery by residual hyperaemia induced by EMS does not accelerate the rate of aerobic metabolism during heavy exercise at least in trained subjects.

  3. Training-induced acceleration of O(2) uptake on-kinetics precedes muscle mitochondrial biogenesis in humans.

    Science.gov (United States)

    Zoladz, Jerzy A; Grassi, Bruno; Majerczak, Joanna; Szkutnik, Zbigniew; Korostyński, Michał; Karasiński, Janusz; Kilarski, Wincenty; Korzeniewski, Bernard

    2013-04-01

    The effects of 5 weeks of moderate-intensity endurance training on pulmonary oxygen uptake kinetics (V(O(2)) on-kinetics) were studied in 15 healthy men (mean ± SD: age 22.7 ± 1.8 years, body weight 76.4 ± 8.9 kg and maximal V(O(2)) 46.0 ± 3.7 ml kg(-1) min(-1)). Training caused a significant acceleration (P = 0.003) of V(O(2)) on-kinetics during moderate-intensity cycling (time constant of the 'primary' component 30.0 ± 6.6 versus 22.8 ± 5.6 s before and after training, respectively) and a significant decrease (P = 0.04) in the amplitude of the primary component (837 ± 351 versus 801 ± 330 ml min(-1)). No changes in myosin heavy chain distribution, muscle fibre capillarization, level of peroxisome proliferator-activated receptor γ coactivator 1α and other markers of mitochondrial biogenesis (mitochondrial DNA copy number, cytochrome c and cytochrome oxidase subunit I contents) in the vastus lateralis were found after training. A significant downregulation in the content of the sarcoplasmic reticulum ATPase 2 (SERCA2; P = 0.03) and a tendency towards a decrease in SERCA1 (P = 0.055) was found after training. The decrease in SERCA1 was positively correlated (P = 0.05) with the training-induced decrease in the gain of the V(O(2)) on-kinetics (ΔV(O(2)) at steady state/Δpower output). In the early stage of training, the acceleration in V(O(2)) on-kinetics during moderate-intensity cycling can occur without enhanced mitochondrial biogenesis or changes in muscle myosin heavy chain distribution and in muscle fibre capillarization. The training-induced decrease of the O(2) cost of cycling could be caused by the downregulation of SERCA pumps.

  4. An Active Learning Mammalian Skeletal Muscle Lab Demonstrating Contractile and Kinetic Properties of Fast- and Slow-Twitch Muscle

    Science.gov (United States)

    Head, S. I.; Arber, M. B.

    2013-01-01

    The fact that humans possess fast and slow-twitch muscle in the ratio of approximately 50% has profound implications for designing exercise training strategies for power and endurance activities. With the growth of exercise and sport science courses, we have seen the need to develop an undergraduate student laboratory that demonstrates the basic…

  5. Muscle oxygen kinetics at onset of intense dynamic exercise in humans

    DEFF Research Database (Denmark)

    Bangsbo, J; Krustrup, P; González-Alonso, J

    2000-01-01

    The present study examined the onset and the rate of rise of muscle oxidation during intense exercise in humans and whether oxygen availability limits muscle oxygen uptake in the initial phase of intense exercise. Six subjects performed 3 min of intense one-legged knee-extensor exercise [65.3 +/-...

  6. Concentric resistance training increases muscle strength without affecting microcirculation

    International Nuclear Information System (INIS)

    Weber, Marc-Andre; Hildebrandt, Wulf; Schroeder, Leif; Kinscherf, Ralf; Krix, Martin; Bachert, Peter; Delorme, Stefan; Essig, Marco; Kauczor, Hans-Ulrich; Krakowski-Roosen, Holger

    2010-01-01

    Purpose: While the evidence is conclusive regarding the positive effects of endurance training, there is still some controversy regarding the effects of resistance training on muscular capillarity. Thus, the purpose was to assess whether resistance strength training influences resting skeletal muscle microcirculation in vivo. Materials and methods: Thirty-nine middle-aged subjects (15 female, 24 male; mean age, 54 ± 9 years) were trained twice a week on an isokinetic system (altogether 16 sessions lasting 50 min, intensity 75% of maximum isokinetic and isometric force of knee flexors and extensors). To evaluate success of training, cross-sectional area (CSA) of the quadriceps femoris muscle and its isokinetic and isometric force were quantified. Muscular capillarization was measured in biopsies of the vastus lateralis muscle. In vivo, muscular energy and lipid metabolites were quantified by magnetic resonance spectroscopy and parameters of muscular microcirculation, such as local blood volume, blood flow and velocity, by contrast-enhanced ultrasound analyzing replenishment kinetics. Results: The significant (P 2 after training) and in absolute muscle strength (isometric, 146 ± 44 vs. 174 ± 50 Nm; isokinetic, 151 ± 53 vs. 174 ± 62 Nm) demonstrated successful training. Neither capillary density ex vivo (351 ± 75 vs. 326 ± 62) nor ultrasonographic parameters of resting muscle perfusion were significantly different (blood flow, 1.2 ± 1.2 vs. 1.1 ± 1.1 ml/min/100 g; blood flow velocity, 0.49 ± 0.44 vs. 0.52 ± 0.74 mm s -1 ). Also, the intensities of high-energy phosphates phosphocreatine and β-adenosintriphosphate were not different after training within the skeletal muscle at rest (β-ATP/phosphocreatine, 0.29 ± 0.06 vs. 0.28 ± 0.04). Conclusion: The significant increase in muscle size and strength in response to concentric isokinetic and isometric resistance training occurs without an increase in the in vivo microcirculation of the skeletal muscles at

  7. Concentric resistance training increases muscle strength without affecting microcirculation

    Energy Technology Data Exchange (ETDEWEB)

    Weber, Marc-Andre [Department of Diagnostic and Interventional Radiology, University of Heidelberg, Heidelberg (Germany)], E-mail: MarcAndre.Weber@med.uni-heidelberg.de; Hildebrandt, Wulf [Immunochemistry, German Cancer Research Center (dkfz), Heidelberg (Germany); Schroeder, Leif [Medical Physics in Radiology, German Cancer Research Center (dkfz), Heidelberg (Germany); Kinscherf, Ralf [Department of Anatomy and Developmental Biology, University of Heidelberg, Heidelberg (Germany); Krix, Martin [Radiology, German Cancer Research Center (dkfz), Heidelberg (Germany); Bachert, Peter [Medical Physics in Radiology, German Cancer Research Center (dkfz), Heidelberg (Germany); Delorme, Stefan; Essig, Marco [Radiology, German Cancer Research Center (dkfz), Heidelberg (Germany); Kauczor, Hans-Ulrich [Department of Diagnostic and Interventional Radiology, University of Heidelberg, Heidelberg (Germany); Krakowski-Roosen, Holger [National Center for Tumor Diseases (NCT), Heidelberg (Germany)

    2010-03-15

    Purpose: While the evidence is conclusive regarding the positive effects of endurance training, there is still some controversy regarding the effects of resistance training on muscular capillarity. Thus, the purpose was to assess whether resistance strength training influences resting skeletal muscle microcirculation in vivo. Materials and methods: Thirty-nine middle-aged subjects (15 female, 24 male; mean age, 54 {+-} 9 years) were trained twice a week on an isokinetic system (altogether 16 sessions lasting 50 min, intensity 75% of maximum isokinetic and isometric force of knee flexors and extensors). To evaluate success of training, cross-sectional area (CSA) of the quadriceps femoris muscle and its isokinetic and isometric force were quantified. Muscular capillarization was measured in biopsies of the vastus lateralis muscle. In vivo, muscular energy and lipid metabolites were quantified by magnetic resonance spectroscopy and parameters of muscular microcirculation, such as local blood volume, blood flow and velocity, by contrast-enhanced ultrasound analyzing replenishment kinetics. Results: The significant (P < 0.001) increase in CSA (60 {+-} 16 before vs. 64 {+-} 15 cm{sup 2} after training) and in absolute muscle strength (isometric, 146 {+-} 44 vs. 174 {+-} 50 Nm; isokinetic, 151 {+-} 53 vs. 174 {+-} 62 Nm) demonstrated successful training. Neither capillary density ex vivo (351 {+-} 75 vs. 326 {+-} 62) nor ultrasonographic parameters of resting muscle perfusion were significantly different (blood flow, 1.2 {+-} 1.2 vs. 1.1 {+-} 1.1 ml/min/100 g; blood flow velocity, 0.49 {+-} 0.44 vs. 0.52 {+-} 0.74 mm s{sup -1}). Also, the intensities of high-energy phosphates phosphocreatine and {beta}-adenosintriphosphate were not different after training within the skeletal muscle at rest ({beta}-ATP/phosphocreatine, 0.29 {+-} 0.06 vs. 0.28 {+-} 0.04). Conclusion: The significant increase in muscle size and strength in response to concentric isokinetic and isometric

  8. Electromyographic analysis of knee push up plus variations: what is the influence of the kinetic chain on scapular muscle activity?

    Science.gov (United States)

    Maenhout, A; Van Praet, K; Pizzi, L; Van Herzeele, M; Cools, A

    2010-11-01

    First, to look for appropriate closed kinetic chain exercises to restore intramuscular imbalance between upper trapezius (UT) and serratus anterior (SA) in overhead athletes. Second, to determine the influence of using diagonal pattern muscle recruitment during knee push up plus (KPP) exercises on scapular electromyographic activity. Single group repeated-measures design. Controlled laboratory study. Thirty-two physically active individuals in good general health who did not have a history of neck and/or shoulder injury or surgery nor participated in high-level overhead sports or performed upper limb strength training for more than 5 h/week. Interventions Subjects performed the standard KPP and six variations. Electromyographic activity of the three trapezius parts and the SA. Four exercises with a low UT/SA can be selected for rehabilitation of intramuscular balance: standard KPP, KPP with homolateral leg extension, KPP with a wobble board and homolateral leg extension and one-handed KPP. The use of a wobble board during KPP exercises and performance on one hand has no influence on SA electromyographic activity. Heterolateral leg extension during KPP stimulates lower trapezius activity, whereas homolateral leg extension stimulates SA activity. In case of intramuscular scapular imbalance, some exercises are preferable over others because of their low UT/SA ratio. The use of a kinetic chain approach during KPP exercises influences scapular muscle activity.

  9. Muscle glycogen reduction in man: relationship between surface EMG activity and oxygen uptake kinetics during heavy exercise.

    Science.gov (United States)

    Osborne, Mark A; Schneider, Donald A

    2006-01-01

    The purpose of this study was to determine whether muscle glycogen reduction prior to exercise would alter muscle fibre recruitment pattern and change either on-transient O2 uptake (VO2) kinetics or the VO2 slow component. Eight recreational cyclists (VO2peak, 55.6 +/- 1.3 ml kg (-1) min(-1)) were studied during 8 min of heavy constant-load cycling performed under control conditions (CON) and under conditions of reduced type I muscle glycogen content (GR). VO2 was measured breath-by-breath for the determination of VO2 kinetics using a double-exponential model with independent time delays. VO2 was higher in the GR trial compared to the CON trial as a result of augmented phase I and II amplitudes, with no difference between trials in the phase II time constant or the magnitude of the slow component. The mean power frequency (MPF) of electromyography activity for the vastus medialis increased over time during both trials, with a greater rate of increase observed in the GR trial compared to the CON trial. The results suggest that the recruitment of additional type II motor units contributed to the slow component in both trials. An increase in fat metabolism and augmented type II motor unit recruitment contributed to the higher VO2 in the GR trial. However, the greater rate of increase in the recruitment of type II motor units in the GR trial may not have been of sufficient magnitude to further elevate the slow component when VO2 was already high and approaching VO2peak .

  10. 31P saturation transfer and phosphocreatine imaging in the monkey brain

    International Nuclear Information System (INIS)

    Mora, B.; Narasimhan, P.T.; Ross, B.D.; Allman, J.; Barker, P.B.

    1991-01-01

    31 P magnetic resonance imaging with chemical-shift discrimination by selective excitation has been employed to determine the phosphocreatine (PCr) distribution in the brains of three juvenile macaque monkeys. PCr images were also obtained while saturating the resonance of the γ-phosphate of ATP, which allowed the investigation of the chemical exchange between PCr and the γ-phosphate of ATP catalyzed by creatine kinase. Superposition of the PCr images over the proton image of the same monkey brain revealed topological variations in the distribution of PCr and creatine kinase activity. PCr images were also obtained with and without visual stimulation. In two out of four experiments, an apparently localized decrease in PCr concentration was noted in visual cortex upon visual stimulation. This result is interpreted in terms of a possible role for the local ADP concentration in stimulating the accompanying metabolic response

  11. Influence of short-term unweighing and reloading on running kinetics and muscle activity.

    Science.gov (United States)

    Sainton, Patrick; Nicol, Caroline; Cabri, Jan; Barthelemy-Montfort, Joëlle; Berton, Eric; Chavet, Pascale

    2015-05-01

    In running, body weight reduction is reported to result in decreased lower limb muscle activity with no change in the global activation pattern (Liebenberg et al. in J Sports Sci 29:207-214). Our study examined the acute effects on running mechanics and lower limb muscle activity of short-term unweighing and reloading conditions while running on a treadmill with a lower body positive pressure (LBPP) device. Eleven healthy males performed two randomized running series of 9 min at preferred speed. Each series included three successive running conditions of 3 min [at 100 % body weight (BW), 60 or 80 % BW, and 100 % BW]. Vertical ground reaction force and center of mass accelerations were analyzed together with surface EMG activity recorded from six major muscles of the left lower limb for the first and last 30 s of each running condition. Effort sensation and mean heart rate were also recorded. In both running series, the unloaded running pattern was characterized by a lower step frequency (due to increased flight time with no change in contact time), lower impact and active force peaks, and also by reduced loading rate and push-off impulse. Amplitude of muscle activity overall decreased, but pre-contact and braking phase extensor muscle activity did not change, whereas it was reduced during the subsequent push-off phase. The combined neuro-mechanical changes suggest that LBPP technology provides runners with an efficient support during the stride. The after-effects recorded after reloading highlight the fact that 3 min of unweighing may be sufficient for updating the running pattern.

  12. Effects of hypo- und hyperthyroidism on skeletal muscle metabolism

    International Nuclear Information System (INIS)

    Moka, D.; Theissen, P.; Linden, A.; Waters, W.; Schicha, H.

    1991-01-01

    31 P magnetic resonance spectroscopy allows non-invasive evaluation of phosphorus metabolism in man. The purpose of the present study was to assess the influence of hyper- and hypothyroidism on the metabolism of resting human skeletal muscle. The present data show that quantitative measurement of phosphate metabolism by NMR is possible as also demonstrated by other studies. Using a quantitative evaluation method with an external standard, significant differences in the levels of phosphocreatine, adenosintriphosphate, and phosphodiesters were found. In hypothyroid patients a TSH-dependent increase in phosphodiesters and a decrease in adenosintriphosphate and phosphocreatine was observed. In hyperthyroidism a similar decrease in adenosintriphosphate but a considerably higher decrease in phosphocreatine occurred. In the light of the results of other studies of muscle matabolism, these changes appear to be non-specific so that further studies are required to assess the clinical value of such measurements. (orig.) [de

  13. Kinetics and Muscle Activity Patterns during Unweighting and Reloading Transition Phases in Running.

    Directory of Open Access Journals (Sweden)

    Patrick Sainton

    Full Text Available Amongst reduced gravity simulators, the lower body positive pressure (LBPP treadmill is emerging as an innovative tool for both rehabilitation and fundamental research purposes as it allows running while experiencing reduced vertical ground reaction forces. The appropriate use of such a treadmill requires an improved understanding of the associated neuromechanical changes. This study concentrates on the runner's adjustments to LBPP-induced unweighting and reloading during running. Nine healthy males performed two running series of nine minutes at natural speed. Each series comprised three sequences of three minutes at: 100% bodyweight (BW, 60 or 80% BW, and 100% BW. The progressive unweighting and reloading transitions lasted 10 to 15 s. The LBPP-induced unweighting level, vertical ground reaction force and center of mass accelerations were analyzed together with surface electromyographic activity from 6 major lower limb muscles. The analyses of stride-to-stride adjustments during each transition established highly linear relationships between the LBPP-induced progressive changes of BW and most mechanical parameters. However, the impact peak force and the loading rate systematically presented an initial 10% increase with unweighting which could result from a passive mechanism of leg retraction. Another major insight lies in the distinct neural adjustments found amongst the recorded lower-limb muscles during the pre- and post-contact phases. The preactivation phase was characterized by an overall EMG stability, the braking phase by decreased quadriceps and soleus muscle activities, and the push-off phase by decreased activities of the shank muscles. These neural changes were mirrored during reloading. These neural adjustments can be attributed in part to the lack of visual cues on the foot touchdown. These findings highlight both the rapidity and the complexity of the neuromechanical changes associated with LBPP-induced unweighting and reloading

  14. Kinetics and Muscle Activity Patterns during Unweighting and Reloading Transition Phases in Running

    Science.gov (United States)

    Sainton, Patrick; Nicol, Caroline; Cabri, Jan; Barthèlemy-Montfort, Joëlle; Chavet, Pascale

    2016-01-01

    Amongst reduced gravity simulators, the lower body positive pressure (LBPP) treadmill is emerging as an innovative tool for both rehabilitation and fundamental research purposes as it allows running while experiencing reduced vertical ground reaction forces. The appropriate use of such a treadmill requires an improved understanding of the associated neuromechanical changes. This study concentrates on the runner’s adjustments to LBPP-induced unweighting and reloading during running. Nine healthy males performed two running series of nine minutes at natural speed. Each series comprised three sequences of three minutes at: 100% bodyweight (BW), 60 or 80% BW, and 100% BW. The progressive unweighting and reloading transitions lasted 10 to 15 s. The LBPP-induced unweighting level, vertical ground reaction force and center of mass accelerations were analyzed together with surface electromyographic activity from 6 major lower limb muscles. The analyses of stride-to-stride adjustments during each transition established highly linear relationships between the LBPP-induced progressive changes of BW and most mechanical parameters. However, the impact peak force and the loading rate systematically presented an initial 10% increase with unweighting which could result from a passive mechanism of leg retraction. Another major insight lies in the distinct neural adjustments found amongst the recorded lower-limb muscles during the pre- and post-contact phases. The preactivation phase was characterized by an overall EMG stability, the braking phase by decreased quadriceps and soleus muscle activities, and the push-off phase by decreased activities of the shank muscles. These neural changes were mirrored during reloading. These neural adjustments can be attributed in part to the lack of visual cues on the foot touchdown. These findings highlight both the rapidity and the complexity of the neuromechanical changes associated with LBPP-induced unweighting and reloading during running

  15. Thick-to-Thin Filament Surface Distance Modulates Cross-Bridge Kinetics in Drosophila Flight Muscle

    Energy Technology Data Exchange (ETDEWEB)

    Tanner, Bertrand C.W.; Farman, Gerrie P.; Irving, Thomas C.; Maughan, David W.; Palmer, Bradley M.; Miller, Mark S. (IIT); (Vermont); (BU)

    2012-09-19

    The demembranated (skinned) muscle fiber preparation is widely used to investigate muscle contraction because the intracellular ionic conditions can be precisely controlled. However, plasma membrane removal results in a loss of osmotic regulation, causing abnormal hydration of the myofilament lattice and its proteins. We investigated the structural and functional consequences of varied myofilament lattice spacing and protein hydration on cross-bridge rates of force development and detachment in Drosophila melanogaster indirect flight muscle, using x-ray diffraction to compare the lattice spacing of dissected, osmotically compressed skinned fibers to native muscle fibers in living flies. Osmolytes of different sizes and exclusion properties (Dextran T-500 and T-10) were used to differentially alter lattice spacing and protein hydration. At in vivo lattice spacing, cross-bridge attachment time (t{sub on}) increased with higher osmotic pressures, consistent with a reduced cross-bridge detachment rate as myofilament protein hydration decreased. In contrast, in the swollen lattice, t{sub on} decreased with higher osmotic pressures. These divergent responses were reconciled using a structural model that predicts t{sub on} varies inversely with thick-to-thin filament surface distance, suggesting that cross-bridge rates of force development and detachment are modulated more by myofilament lattice geometry than protein hydration. Generalizing these findings, our results suggest that cross-bridge cycling rates slow as thick-to-thin filament surface distance decreases with sarcomere lengthening, and likewise, cross-bridge cycling rates increase during sarcomere shortening. Together, these structural changes may provide a mechanism for altering cross-bridge performance throughout a contraction-relaxation cycle.

  16. Kinetic analysis of cooking losses from beef and other animal muscles heated in a water bath--effect of sample dimensions and prior freezing and ageing.

    Science.gov (United States)

    Oillic, Samuel; Lemoine, Eric; Gros, Jean-Bernard; Kondjoyan, Alain

    2011-07-01

    Cooking loss kinetics were measured on cubes and parallelepipeds of beef Semimembranosus muscle ranging from 1 cm × 1 cm × 1 cm to 7 cm × 7 cm × 28 cm in size. The samples were water bath-heated at three different temperatures, i.e. 50°C, 70°C and 90°C, and for five different times. Temperatures were simulated to help interpret the results. Pre-freezing the sample, difference in ageing time, and in muscle fiber orientation had little influence on cooking losses. At longer treatment times, the effects of sample size disappeared and cooking losses depended only on the temperature. A selection of the tests was repeated on four other beef muscles and on veal, horse and lamb Semimembranosus muscle. Kinetics followed similar curves in all cases but resulted in different final water contents. The shape of the kinetics curves suggests first-order kinetics. Copyright © 2011 The American Meat Science Association. Published by Elsevier Ltd. All rights reserved.

  17. A potential role for muscle in glucose homeostasis: in vivo kinetic studies in glycogen storage disease type 1a and fructose-1,6-bisphosphatase deficiency

    NARCIS (Netherlands)

    Huidekoper, Hidde H.; Visser, Gepke; Ackermans, Mariëtte T.; Sauerwein, Hans P.; Wijburg, Frits A.

    2010-01-01

    A potential role for muscle in glucose homeostasis was recently suggested based on characterization of extrahepatic and extrarenal glucose-6-phosphatase (glucose-6-phosphatase-beta). To study the role of extrahepatic tissue in glucose homeostasis during fasting glucose kinetics were studied in two

  18. The effects of body weight unloading on kinetics and muscle activity of overweight males during Overground walking.

    Science.gov (United States)

    Fischer, Arielle G; Wolf, Alon

    2018-02-01

    Excess body weight has become a major worldwide health and social epidemic. Training with body weight unloading, is a common method for gait corrections for various neuromuscular impairments. In the present study we assessed the effects of body weight unloading on knee and ankle kinetics and muscle activation of overweight subjects walking overground under various levels of body weight unloading. Ten overweight subjects (25 ≤ BMI weight unloading experimental conditions. Gait parameters assessed under these conditions included knee and ankle flexion moments and the Electromygraphic activity of the Tibialis Anterior, Lateral Gastrocnemius and Vastus Lateralis. Increasing body weight unloading levels from 0% to 30% was found to significantly reduce the peak knee flexion and ankle plantarflexion moments. Also observed was a significant reduction in muscle activity of the Tibialis Anterior, Lateral Gastrocnemius and Vastus Lateralis under the three body-weight unloading conditions. Our results demonstrate that a reduction of up to 30% overweight subjects' body weight during gait is conducive to a reduction in the knee and ankle flexion moments and in the balancing net quadriceps moment and ankle flexors moment. The newly devised body weight unloading device is therefore an effective method for reducing joint loads allowing overweight people who require controlled weight bearing scenarios to retrain their gait while engaging in sustained walking exercise. Copyright © 2018 Elsevier Ltd. All rights reserved.

  19. Three-layered architecture of the popliteal fascia that acts as a kinetic retinaculum for the hamstring muscles.

    Science.gov (United States)

    Satoh, Masahiro; Yoshino, Hiroyuki; Fujimura, Akira; Hitomi, Jiro; Isogai, Sumio

    2016-09-01

    When patients report pain in the popliteal fossa upon knee extension, the pain is usually localized in the lower region of the popliteal fossa. However, some patients complain of pain in the upper region of the popliteal fossa as the knee is flexed, which motivated us to examine the role of the popliteal fascia as the retinaculum of the hamstring muscles. Thirty-four thighs from 19 Japanese cadavers were dissected. The popliteal fascia was defined as the single aponeurotic sheet covering the popliteal fossa. We found that the fascia acted as a three-layered retinaculum for the flexor muscles of the thigh and provided a secure route for neurovascular structures to the lower leg in any kinetic position of the knee joint. The superficial layer of the popliteal fascia covering the thigh was strongly interwoven with the epimysium of biceps femoris along its lateral aspect and with that of the semimembranosus along its medial aspect, ensuring that the flexor muscles remained in their correct positions. The intermediate layer arose from the medial side of biceps femoris and merged medially with the superficial layer. The profound layer stretched transversely between the biceps femoris and the semimembranosus. Moreover, we investigated the nerve distribution in the popliteal fascia using Sihler's staining and whole-mount immunostaining for neurofilaments. The three-layered fascia was constantly innervated by branches from the posterior femoral cutaneous or saphenous nerve. The nerves were closely related and distributed to densely packed collagen fibers in the superficial layer as free or encapsulated nerve endings, suggesting that the fascia is involved in pain in the upper region of the popliteal fossa.

  20. V̇O2 and Muscle Deoxygenation Kinetics During Skating: Comparison Between Slide Board and Treadmill Skating.

    Science.gov (United States)

    Piucco, Tatiane; Soares, Rogério; Diefenthaeler, Fernando; Millet, Guillaume; Murias, Juan

    2017-11-15

    this study aimed to compare the oxygen uptake (V̇O 2 ) kinetics during skating on a treadmill and skating on a slide board and discuss potential mechanisms that might control the V̇O 2 kinetics responses during skating. breath-by-breath pulmonary V̇O 2 and near-infrared spectroscopy-derived muscle deoxygenation ([HHbMb]) were monitored continuously in 12 well-trained young long track speed skaters. On-transient V̇O 2 and [HHbMb] responses to skating on a treadmill and skating on a slide board at 80% of the estimated gas exchange threshold were fitted as mono-exponential function. The signals were time aligned, and the individual [HHbMb]-to-V̇O 2 ratio was calculated as the average value from 20-120 s after exercise starts. the time constants for the adjustment of phase II V̇O 2 (τ V̇O 2 ) and [HHbMb] (τ[HHbMb]) were low and similar between slide board vs. treadmill skating (18.1 ± 3.4 vs. 18.9 ± 3.6 for τ V̇O 2 and 12.6 ± 4.0 vs. 12.4 ± 4.0 s for τ[HHbMb]). The [HHbMb]/V̇O 2 ratio was not different from 1.0 (p > 0.05) in both conditions. the fast V̇O 2 kinetics during skating suggest that chronical adaptation to skating might overcome any possible restriction in leg blood flow during low intensity exercise. The [HHbMb]/V̇O 2 ratio values also suggest a good matching of O 2 delivery to O 2 utilization in trained speed skaters. The similar τ V̇O 2 and τ [HHbMb] values between slide board and treadmill further reinforce the validity of using a slide board for skating testing and training purposes.

  1. Faster and stronger manifestation of mitochondrial diseases in skeletal muscle than in heart related to cytosolic inorganic phosphate (Pi) accumulation.

    Science.gov (United States)

    Korzeniewski, Bernard

    2016-08-01

    A model of the cell bioenergetic system was used to compare the effect of oxidative phosphorylation (OXPHOS) deficiencies in a broad range of moderate ATP demand in skeletal muscle and heart. Computer simulations revealed that kinetic properties of the system are similar in both cases despite the much higher mitochondria content and "basic" OXPHOS activity in heart than in skeletal muscle, because of a much higher each-step activation (ESA) of OXPHOS in skeletal muscle than in heart. Large OXPHOS deficiencies lead in both tissues to a significant decrease in oxygen consumption (V̇o2) and phosphocreatine (PCr) and increase in cytosolic ADP, Pi, and H(+) The main difference between skeletal muscle and heart is a much higher cytosolic Pi concentration in healthy tissue and much higher cytosolic Pi accumulation (level) at low OXPHOS activities in the former, caused by a higher PCr level in healthy tissue (and higher total phosphate pool) and smaller Pi redistribution between cytosol and mitochondria at OXPHOS deficiency. This difference does not depend on ATP demand in a broad range. A much greater Pi increase and PCr decrease during rest-to-moderate work transition in skeletal muscle at OXPHOS deficiencies than at normal OXPHOS activity significantly slows down the V̇o2 on-kinetics. Because high cytosolic Pi concentrations cause fatigue in skeletal muscle and can compromise force generation in skeletal muscle and heart, this system property can contribute to the faster and stronger manifestation of mitochondrial diseases in skeletal muscle than in heart. Shortly, skeletal muscle with large OXPHOS deficiencies becomes fatigued already during low/moderate exercise. Copyright © 2016 the American Physiological Society.

  2. Barefoot vs common footwear: A systematic review of the kinematic, kinetic and muscle activity differences during walking.

    Science.gov (United States)

    Franklin, Simon; Grey, Michael J; Heneghan, Nicola; Bowen, Laura; Li, François-Xavier

    2015-09-01

    Habitual footwear use has been reported to influence foot structure with an acute exposure being shown to alter foot position and mechanics. The foot is highly specialised thus these changes in structure/position could influence functionality. This review aims to investigate the effect of footwear on gait, specifically focussing on studies that have assessed kinematics, kinetics and muscle activity between walking barefoot and in common footwear. In line with PRISMA and published guidelines, a literature search was completed across six databases comprising Medline, EMBASE, Scopus, AMED, Cochrane Library and Web of Science. Fifteen of 466 articles met the predetermined inclusion criteria and were included in the review. All articles were assessed for methodological quality using a modified assessment tool based on the STROBE statement for reporting observational studies and the CASP appraisal tool. Walking barefoot enables increased forefoot spreading under load and habitual barefoot walkers have anatomically wider feet. Spatial-temporal differences including, reduced step/stride length and increased cadence, are observed when barefoot. Flatter foot placement, increased knee flexion and a reduced peak vertical ground reaction force at initial contact are also reported. Habitual barefoot walkers exhibit lower peak plantar pressures and pressure impulses, whereas peak plantar pressures are increased in the habitually shod wearer walking barefoot. Footwear particularly affects the kinematics and kinetics of gait acutely and chronically. Little research has been completed in older age populations (50+ years) and thus further research is required to better understand the effect of footwear on walking across the lifespan. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

  3. The effects of RSR13 on microvascular Po2 kinetics and muscle contractile performance in the rat arterial ligation model of peripheral arterial disease.

    Science.gov (United States)

    Watanabe, Aiko; Poole, David C; Kano, Yutaka

    2017-10-01

    Exercise intolerance and claudication are symptomatic of peripheral arterial disease. There is a close relationship between muscle O 2 delivery, microvascular oxygen partial pressure (P mv O 2 ), and contractile performance. We therefore hypothesized that a reduction of hemoglobin-oxygen affinity via RSR13 would maintain a higher P mv O 2 and enhance blood-muscle O 2 transport and contractile function. In male Wistar rats (12 wk of age), we created hindlimb ischemia via right-side iliac artery ligation (AL). The contralateral (left) muscle served as control (CONT). Seven days after AL, phosphorescence-quenching techniques were used to measure P mv O 2 at rest and during contractions (electrical stimulation; 1 Hz, 300 s) in tibialis anterior muscle (TA) under saline ( n = 10) or RSR13 ( n = 10) conditions. RSR13 at rest increased TA P mv O 2 in CONT (13.9 ± 1.6 to 19.3 ± 1.9 Torr, P < 0.05) and AL (9.0 ± 0.5 to 9.9 ± 0.7 Torr, P < 0.05). Furthermore, RSR13 extended maintenance of the initial TA force (i.e., improved contractile performance) such that force was not decreased significantly until contraction 240 vs. 150 in CONT and 80 vs. 20 in AL. This improved muscle endurance with RSR13 was accompanied by a greater ΔP mv O 2 (P mv O 2 decrease from baseline) (CONT, 7.4 ± 1.0 to 11.2 ± 1.3; AL, 6.9 ± 0.5 to 8.6 ± 0.6 Torr, both P < 0.05). Whereas RSR13 did not alter the kinetics profile of P mv O 2 (i.e., mean response time) substantially during contractions, muscle force was elevated, and the ratio of muscle force to P mv O 2 increased. In conclusion, reduction of hemoglobin-oxygen affinity via RSR13 in AL increased P mv O 2 and improved muscle contractile performance most likely via enhanced blood-muscle O 2 diffusion. NEW & NOTEWORTHY This is the first investigation to examine the effect of RSR13 (erythrocyte allosteric effector) on skeletal muscle microvascular oxygen partial pressure kinetics and contractile function using an arterial ligation model of

  4. Slow receptor dissociation kinetics differentiate macitentan from other endothelin receptor antagonists in pulmonary arterial smooth muscle cells.

    Directory of Open Access Journals (Sweden)

    John Gatfield

    Full Text Available Two endothelin receptor antagonists (ERAs, bosentan and ambrisentan, are currently approved for the treatment of pulmonary arterial hypertension (PAH, a devastating disease involving an activated endothelin system and aberrant contraction and proliferation of pulmonary arterial smooth muscle cells (PASMC. The novel ERA macitentan has recently concluded testing in a Phase III morbidity/mortality clinical trial in PAH patients. Since the association and dissociation rates of G protein-coupled receptor antagonists can influence their pharmacological activity in vivo, we used human PASMC to characterize inhibitory potency and receptor inhibition kinetics of macitentan, ambrisentan and bosentan using calcium release and inositol-1-phosphate (IP(1 assays. In calcium release assays macitentan, ambrisentan and bosentan were highly potent ERAs with K(b values of 0.14 nM, 0.12 nM and 1.1 nM, respectively. Macitentan, but not ambrisentan and bosentan, displayed slow apparent receptor association kinetics as evidenced by increased antagonistic potency upon prolongation of antagonist pre-incubation times. In compound washout experiments, macitentan displayed a significantly lower receptor dissociation rate and longer receptor occupancy half-life (ROt(1/2 compared to bosentan and ambrisentan (ROt(1/2:17 minutes versus 70 seconds and 40 seconds, respectively. Because of its lower dissociation rate macitentan behaved as an insurmountable antagonist in calcium release and IP(1 assays, and unlike bosentan and ambrisentan it blocked endothelin receptor activation across a wide range of endothelin-1 (ET-1 concentrations. However, prolongation of the ET-1 stimulation time beyond ROt(1/2 rendered macitentan a surmountable antagonist, revealing its competitive binding mode. Bosentan and ambrisentan behaved as surmountable antagonists irrespective of the assay duration and they lacked inhibitory activity at high ET-1 concentrations. Thus, macitentan is a competitive

  5. A comparison of the kinematics, kinetics and muscle activity between pneumatic and free weight resistance.

    Science.gov (United States)

    Frost, David Michael; Cronin, John Barry; Newton, Robert Usher

    2008-12-01

    Pneumatic devices provide a resistance comprising minimal mass, possibly affording greater movement velocities, compared to free weight, while reducing the influence of momentum. Thirty men completed three testing sessions [free weight (FW), ballistic (BALL) and pneumatic (P)] each consisting of a one repetition maximum (1RM) and six sets (15, 30, 45, 60, 75 and 90% 1RM) of four explosive repetitions of a bench press. Dependent variables were expressed as mean and as a percentage of the concentric displacement. Significant differences (P < 0.05) were evaluated using two way repeated measures ANOVAs with Holm-Sidak post hoc comparisons. On average, the mean and peak P velocity were 36.5 and 28.3% higher than FW, and 22.9 and 19.1% higher than the BALL movements. The FW and BALL peak force were both significantly higher than the P (26.3 and 22.7% for FW and BALL, respectively). BALL mean power output was significantly higher than the FW and P at loads of 15 and 30% 1RM; however, between loads of 60-90% 1RM the highest mean power was produced with a P resistance. A 15% 1RM load maximized the peak power for each condition and no significant differences were found between the P and BALL. For loads of 45-90% 1RM the force, power and muscle activity were higher during the last 10-20% of the concentric displacement when subjects employed the P resistance. In summary, pneumatic resistance may offer specific advantages over loads comprising only mass (FW and BALL), although not without its own limitations.

  6. Musculus gastrocnemius tetanus kinetics in alcohol-intoxicated rats with experimentally-induced hindlimb vascular ischemia under conditions of low-frequence muscle fatigue

    Directory of Open Access Journals (Sweden)

    O. A. Melnychuk

    2014-04-01

    Full Text Available Alcohol intoxication and ischemic injury of skeletal muscles often accompany each other. It is shown that patients hospitalized with chronic alcoholism develop muscle fatigue. Skeletal muscle dysfunction in alcohol-dependent patients is caused by ethanol-associated myofibrillar atrophy and metabolic disbalance, while compression-ischemic lesions result from unconsciousness of the patient, in case of taking the critical alcohol dose. Therefore, the aim of this study is to discover typical m. gastrocnemius (cap. med. tetanic kinetics changes in alcohol intoxicated rats with experimentally induced vascular ischemia of hindlimb muscles under conditions of low-frequency progressive muscle fatigue. Experiments were carried out on 10 young male Wistar rats (149.5 ± 5.8 g kept under standard vivarium conditions and diet. The investigation was conducted in two phases: chronic (30 days and acute (3 hours experiment. All surgical procedures were carried out aseptically under general anesthesia. Ishemic m. gastrocnemius (cap. med. tetanic kinetic changes and force productivity in alcohol intoxicated rats were investigated in the isometric mode, with direct electrical stimulation. The fatigue of m. gastrocnemius (cap. med. was evaluated by three characteristic criteria: the first sag effect, the secondary force rise, the second sag effect. There have been 10 similar experiments: 5 series in each study group with 10 tetanic runs in each series. The highest amplitude of the native m. gastrocnemius (cap. med. tetanus relative to isoline was taken as 100% force response. The same pattern of m. gastrocnemius (cap. med. low-frequency fatigue development was found in both rat groups under study. It is evidenced by the absence of substantial m. gastrocnemius (cap. med. tetanus kinetics differences in alcohol intoxicated rats, compared with non-alcohol intoxicated rats during fatigue test. However, the appreciable m. gastrocnemius (cap. med. tetanic force reduction

  7. Gender Differences in the Effect of Tobacco Use on Brain Phosphocreatine Levels in Methamphetamine Dependent Subjects

    Science.gov (United States)

    Sung, Young-Hoon; Yurgelun-Todd, Deborah A.; Kondo, Douglas G.; Shi, Xian-Feng; Lundberg, Kelly J.; Hellem, Tracy L.; Huber, Rebekah S.; McGlade, Erin C.; Jeong, Eun-Kee; Renshaw, Perry F.

    2015-01-01

    Background A high prevalence of tobacco smoking has been observed in methamphetamine users, but there have been no in vivo brain neurochemistry studies addressing gender effects of tobacco smoking in methamphetamine users. Methamphetamine addiction is associated with increased risk of depression and anxiety in females. There is increasing evidence that selective analogues of nicotine, a principal active component of tobacco smoking, may improve depression and cognitive performance in animals and humans. Objectives To investigate the effects of tobacco smoking and gender on brain phosphocreatine (PCr) levels, a marker of brain energy metabolism reported to be reduced in methamphetamine-dependent subjects. Methods Thirty female and twenty-seven male methamphetamine-dependent subjects were evaluated with phosphorus-31 magnetic resonance spectroscopy (31P-MRS) to measure PCr levels within the pregenual anterior cingulate, which has been implicated in methamphetamine neurotoxicity. Results Analysis of covariance revealed that there were statistically significant slope (PCr versus lifetime amount of tobacco smoking) differences between female and male methamphetamine-dependent subjects (p=0.03). In females, there was also a statistically significant interaction between lifetime amounts of tobacco smoking and methamphetamine in regard to PCr levels (p=0.01), which suggests that tobacco smoking may have a more significant positive impact on brain PCr levels in heavy, as opposed to light to moderate, methamphetamine-dependent females. Conclusion These results indicate that tobacco smoking has gender-specific effects in terms of increased anterior cingulate high energy PCr levels in methamphetamine-dependent subjects. Cigarette smoking in methamphetamine-dependent women, particularly those with heavy methamphetamine use, may have a potentially protective effect upon neuronal metabolism. PMID:25871447

  8. Ingestion of Casein in a Milk Matrix Modulates Dietary Protein Digestion and Absorption Kinetics but Does Not Modulate Postprandial Muscle Protein Synthesis in Older Men.

    Science.gov (United States)

    Churchward-Venne, Tyler A; Snijders, Tim; Linkens, Armand M A; Hamer, Henrike M; van Kranenburg, Janneau; van Loon, Luc J C

    2015-07-01

    The slow digestion and amino acid absorption kinetics of isolated micellar casein have been held responsible for its relatively lower postprandial muscle protein synthetic response compared with rapidly digested proteins such as isolated whey. However, casein is normally consumed within a milk matrix. We hypothesized that protein digestion and absorption kinetics and the subsequent muscle protein synthetic response after micellar casein ingestion are modulated by the milk matrix. The aim of this study was to determine the impact of a milk matrix on casein protein digestion and absorption kinetics and postprandial muscle protein synthesis in older men. In a parallel-group design, 32 healthy older men (aged 71 ± 1 y) received a primed continuous infusion of L-[ring-(2)H5]-phenylalanine, L-[ring-3,5-(2)H2]-tyrosine, and L-[1-(13)C]-leucine, and ingested 25 g intrinsically L-[1-(13)C]-phenylalanine and L-[1-(13)C]-leucine labeled casein dissolved in bovine milk serum (Cas+Serum) or water (Cas). Plasma samples and muscle biopsies were collected in the postabsorptive state and for 300 min in the postprandial period to examine whole-body and skeletal muscle protein metabolism. Casein ingestion increased plasma leucine and phenylalanine concentrations and L-[1-(13)C]-phenylalanine enrichments, with a more rapid rise after Cas vs. Cas+Serum. Nonetheless, dietary protein-derived phenylalanine availability did not differ between Cas+Serum (47 ± 2%, mean ± SEM) and Cas (46 ± 3%) when assessed over the 300-min postprandial period (P = 0.80). The milk matrix did not modulate postprandial myofibrillar protein synthesis rates from 0 to 120 min (0.038 ± 0.005 vs. 0.031 ± 0.007%/h) or from 120 to 300 min (0.052 ± 0.004 vs. 0.067 ± 0.005%/h) after Cas+Serum vs. Cas. Similarly, no treatment differences in muscle protein-bound L-[1-(13)C]-phenylalanine enrichments were observed at 120 min (0.003 ± 0.001 vs. 0.002 ± 0.001) or 300 min (0.015 ± 0.002 vs. 0.016 ± 0.002 mole

  9. Defective mitochondrial function in vivo in skeletal muscle in adults with Down's syndrome: a 31P-MRS study.

    Directory of Open Access Journals (Sweden)

    Alexander C Phillips

    Full Text Available Down's syndrome (DS is a developmental disorder associated with intellectual disability (ID. We have previously shown that people with DS engage in very low levels of exercise compared to people with ID not due to DS. Many aspects of the DS phenotype, such as dementia, low activity levels and poor muscle tone, are shared with disorders of mitochondrial origin, and mitochondrial dysfunction has been demonstrated in cultured DS tissue. We undertook a phosphorus magnetic resonance spectroscopy ((31P-MRS study in the quadriceps muscle of 14 people with DS and 11 non-DS ID controls to investigate the post-exercise resynthesis kinetics of phosphocreatine (PCr, which relies on mitochondrial respiratory function and yields a measure of muscle mitochondrial function in vivo. We found that the PCr recovery rate constant was significantly decreased in adults with DS compared to non-DS ID controls (1.7 ± 0.1 min(-1 vs 2.1 ± 0.1 min(-1 respectively who were matched for physical activity levels, indicating that muscle mitochondrial function in vivo is impaired in DS. This is the first study to investigate mitochondrial function in vivo in DS using (31P-MRS. Our study is consistent with previous in vitro studies, supporting a theory of a global mitochondrial defect in DS.

  10. Lactate/H+ transport kinetics in rat skeletal muscle related to fibre type and changes in transport capacity

    DEFF Research Database (Denmark)

    Juel; Pilegaard

    1998-01-01

    muscles, muscles of old rats and rats that had been subjected to high-intensity training, endurance training, repeated exposure to hypoxia, and hypothyroid or hyperthyroid treatments. The lactate/H+ transport capacity of red muscles was greater than that of white muscles, and this difference...... and hypothyroidism was due to a decrease in Vmax. The denervation-induced decline in lactate/H+ transport capacity resulted from both an increased Km and a reduced Vmax. The present data show that muscle type differences and most changes in the lactate/H+ transport capacity are mediated by modifications in Vmax......, which is expected to represent the number of membrane transporter molecules. Km is unaffected by most treatments and appears to be independent of fibre type....

  11. Exercise-induced muscle modifications

    International Nuclear Information System (INIS)

    Kerviler, E. de; Willig, A.L.; Jehenson, P.; Duboc, D.; Syrota, A.

    1990-01-01

    This paper compares changes in muscle proton T2 after exercise in normal subjects and in patients with muscular glycogenoses. Four patients suffering from muscular glycogenosis and eight normal volunteers were studied. Muscle T2s were measured in forearm muscles at rest and after exercise, with a 0.5-T imager. The exercise was performed with handgrips and was evaluated by P-31 spectroscopy (end-exercise decrease in pH and phosphocreatine) performed with a 2-T magnet. In normal subjects, a relative T2 increase, ranging from 14% to 44%, was observed in the exercised muscles. In the patients, who cannot produce lactate during exercise, weak pH variation occurred, and only a slight T2 increase (7% - 9%) was observed

  12. Early time course of N-acetylaspartate, creatine and phosphocreatine, and compounds containing choline in the brain after acute stroke. A proton magnetic resonance spectroscopy study

    DEFF Research Database (Denmark)

    Gideon, P; Henriksen, O; Sperling, B

    1992-01-01

    BACKGROUND AND PURPOSE: The early time course after acute stroke of cerebral N-acetylaspartate, creatine and phosphocreatine, and compounds containing choline was studied in vivo by means of localized water-suppressed proton magnetic resonance spectroscopy. METHODS: Eight patients with acute stroke......, with the loss appearing to occur between 6 and 24 hours after the stroke incident. The reduction in N-acetylaspartate content was greater in the central part than in the peripheral part of the infarcted area. Creatine and phosphocreatine were also reduced in the infarcted area, whereas no significant change...

  13. Bioenergetics of the calf muscle in Friedreich ataxia patients measured by 31P-MRS before and after treatment with recombinant human erythropoietin.

    Directory of Open Access Journals (Sweden)

    Wolfgang Nachbauer

    Full Text Available Friedreich ataxia (FRDA is caused by a GAA repeat expansion in the FXN gene leading to reduced expression of the mitochondrial protein frataxin. Recombinant human erythropoietin (rhuEPO is suggested to increase frataxin levels, alter mitochondrial function and improve clinical scores in FRDA patients. Aim of the present pilot study was to investigate mitochondrial metabolism of skeletal muscle tissue in FRDA patients and examine effects of rhuEPO administration by phosphorus 31 magnetic resonance spectroscopy (31P MRS. Seven genetically confirmed FRDA patients underwent 31P MRS of the calf muscles using a rest-exercise-recovery protocol before and after receiving 3000 IU of rhuEPO for eight weeks. FRDA patients showed more rapid phosphocreatine (PCr depletion and increased accumulation of inorganic phosphate (Pi during incremental exercise as compared to controls. After maximal exhaustive exercise prolonged regeneration of PCR and slowed decline in Pi can be seen in FRDA. PCr regeneration as hallmark of mitochondrial ATP production revealed correlation to activity of complex II/III of the respiratory chain and to demographic values. PCr and Pi kinetics were not influenced by rhuEPO administration. Our results confirm mitochondrial dysfunction and exercise intolerance due to impaired oxidative phosphorylation in skeletal muscle tissue of FRDA patients. MRS did not show improved mitochondrial bioenergetics after eight weeks of rhuEPO exposition in skeletal muscle tissue of FRDA patients.EU Clinical Trials Register2008-000040-13.

  14. The cross-bridge dynamics is determined by two length-independent kinetics: Implications on muscle economy and Frank-Starling Law.

    Science.gov (United States)

    Amiad Pavlov, Daria; Landesberg, Amir

    2016-01-01

    The cellular mechanisms underlying the Frank-Starling Law of the heart and the skeletal muscle force-length relationship are not clear. This study tested the effects of sarcomere length (SL) on the average force per cross-bridge and on the rate of cross-bridge cycling in intact rat cardiac trabeculae (n=9). SL was measured by laser diffraction and controlled with a fast servomotor to produce varying initial SLs. Tetanic contractions were induced by addition of cyclopiazonic acid, to maintain a constant activation. Stress decline and redevelopment in response to identical ramp shortenings, starting at various initial SLs, was analyzed. Both stress decline and redevelopment responses revealed two distinct kinetics: a fast and a slower phase. The duration of the rapid phases (4.2 ± 0.1 msec) was SL-independent. The second slower phase depicted a linear dependence of the rate of stress change on the instantaneous stress level. Identical slopes (70.5 ± 1.6 [1/s], p=0.33) were obtained during ramp shortening at all initial SLs, indicating that the force per cross-bridge and cross-bridge cycling kinetics are length-independent. A decrease in the slope at longer SLs was obtained during stress redevelopment, due to internal shortening. The first phase is attributed to rapid changes in the average force per cross-bridge. The second phase is ascribed to both cross-bridge cycling between its strong and weak conformations and to changes in the number of strong cross-bridges. Cross-bridge cycling kinetics and muscle economy are length-independent and the Frank-Starling Law cannot be attributed to changes in the force per cross-bridge or in the single cross-bridge cycling rates. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. Kinetics on Demand Is a Simple Mathematical Solution that Fits Recorded Caffeine-Induced Luminal SR Ca2+ Changes in Smooth Muscle Cells.

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    Norma C Perez-Rosas

    Full Text Available The process of Ca2+ release from sarcoplasmic reticulum (SR comprises 4 phases in smooth muscle cells. Phase 1 is characterized by a large increase of the intracellular Ca2+ concentration ([Ca2+]i with a minimal reduction of the free luminal SR [Ca2+] ([Ca2+]FSR. Importantly, active SR Ca2+ ATPases (SERCA pumps are necessary for phase 1 to occur. This situation cannot be explained by the standard kinetics that involves a fixed amount of luminal Ca2+ binding sites. A new mathematical model was developed that assumes an increasing SR Ca2+ buffering capacity in response to an increase of the luminal SR [Ca2+] that is called Kinetics-on-Demand (KonD model. This approach can explain both phase 1 and the refractory period associated with a recovered [Ca2+]FSR. Additionally, our data suggest that active SERCA pumps are a requisite for KonD to be functional; otherwise luminal SR Ca2+ binding proteins switch to standard kinetics. The importance of KonD Ca2+ binding properties is twofold: a more efficient Ca2+ release process and that [Ca2+]FSR and Ca2+-bound to SR proteins ([Ca2+]BSR can be regulated separately allowing for Ca2+ release to occur (provided by Ca2+-bound to luminal Ca2+ binding proteins without an initial reduction of the [Ca2+]FSR.

  16. Supra- and Sub-Baseline Phosphocreatine Recovery in Developing Brain after Transient Hypoxia-Ischaemia: Relation to Baseline Energetics, Insult Severity and Outcome

    Science.gov (United States)

    Iwata, Osuke; Iwata, Sachiko; Bainbridge, Alan; De Vita, Enrico; Matsuishi, Toyojiro; Cady, Ernest B.; Robertson, Nicola J.

    2008-01-01

    Following hypoxia-ischaemia (HI), an early biomarker of insult severity is desirable to target neuroprotective therapies to patients most likely to benefit; currently there are no biomarkers within the "latent phase" period before the establishment of secondary energy failure. Brief transient phosphocreatine (PCr) recovery overshoot (measured…

  17. The concentration of N-acetyl aspartate, creatine + phosphocreatine, and choline in different parts of the brain in adulthood and senium

    DEFF Research Database (Denmark)

    Christiansen, P; Toft, P; Larsson, H B

    1993-01-01

    The fully relaxed water signal was used as an internal standard in a STEAM experiment to calculate the concentrations of the metabolites: N-acetyl aspartate (NAA), creatine + phosphocreatine (Cr + PCr), and choline (Cho) containing compounds in four different parts of the brain in two age groups...

  18. Voluntary enhanced cocontraction of hamstring muscles during open kinetic chain leg extension exercise: its potential unloading effect on the anterior cruciate ligament.

    Science.gov (United States)

    Biscarini, Andrea; Benvenuti, Paolo; Botti, Fabio M; Brunetti, Antonella; Brunetti, Orazio; Pettorossi, Vito E

    2014-09-01

    A number of research studies provide evidence that hamstring cocontraction during open kinetic chain knee extension exercises enhances tibiofemoral (TF) stability and reduces the strain on the anterior cruciate ligament. To determine the possible increase in hamstring muscle coactivation caused by a voluntary cocontraction effort during open kinetic chain leg-extension exercises, and to assess whether an intentional hamstring cocontraction can completely suppress the anterior TF shear force during these exercises. Descriptive laboratory study. Knee kinematics as well as electromyographic activity in the semitendinosus (ST), semimembranosus (SM), biceps femoris (BF), and quadriceps femoris muscles were measured in 20 healthy men during isotonic leg extension exercises with resistance (R) ranging from 10% to 80% of the 1-repetition maximum (1RM). The same exercises were also performed while the participants attempted to enhance hamstring coactivation through a voluntary cocontraction effort. The data served as input parameters for a model to calculate the shear and compressive TF forces in leg extension exercises for any set of coactivation patterns of the different hamstring muscles. For R≤ 40% 1RM, the peak coactivation levels obtained with intentional cocontraction (l) were significantly higher (P hamstring muscle, maximum level l was reached at R = 30% 1RM, corresponding to 9.2%, 10.5%, and 24.5% maximum voluntary isometric contraction (MVIC) for the BF, ST, and SM, respectively, whereas the ratio l/l 0 reached its maximum at R = 20% 1RM and was approximately 2, 3, and 4 for the BF, SM, and ST, respectively. The voluntary enhanced coactivation level l obtained for R≤ 30% 1RM completely suppressed the anterior TF shear force developed by the quadriceps during the exercise. In leg extension exercises with resistance R≤ 40% 1RM, coactivation of the BF, SM, and ST can be significantly enhanced (up to 2, 3, and 4 times, respectively) by a voluntary hamstring

  19. Peak Muscle Activation, Joint Kinematics, and Kinetics during Elliptical and Stepping Movement Pattern on a Precor Adaptive Motion Trainer

    Science.gov (United States)

    Rogatzki, Matthew J.; Kernozek, Thomas W.; Willson, John D.; Greany, John F.; Hong, Di-An; Porcari, John P.

    2012-01-01

    Kinematic, kinetic, and electromyography data were collected from the biceps femoris, rectus femoris (RF), gluteus maximus, and erector spinae (ES) during a step and elliptical exercise at a standardized workload with no hand use. Findings depicted 95% greater ankle plantar flexion (p = 0.01), 29% more knee extension (p = 0.003), 101% higher peak…

  20. The effects of short work vs. longer work periods within intermittent exercise on V̇o2p kinetics, muscle deoxygenation, and energy system contribution.

    Science.gov (United States)

    McCrudden, Michael C; Keir, Daniel A; Belfry, Glen R

    2017-06-01

    We examined the effects of inserting 3-s recovery periods during high-intensity cycling exercise at 25-s and 10-s intervals on pulmonary oxygen uptake (V̇o 2p ), muscle deoxygenation [deoxyhemoglobin (HHb)], their associated kinetics (τ), and energy system contributions. Eleven men (24 ± 3 yr) completed two trials of three cycling protocols: an 8-min continuous protocol (CONT) and two 8-min intermittent exercise protocols with work-to-rest periods of 25 s to 3 s (25INT) and 10 s to 3 s (10INT). Each protocol began with a step-transition from a 20-W baseline to a power output (PO) of 60% between lactate threshold and maximal V̇o 2p (Δ60). This PO was maintained for 8 min in CONT, whereas 3-s periods of 20-W cycling were inserted every 10 s and 25 s after the transition to Δ60 in 10INT and 25INT, respectively. Breath-by-breath gas exchange measured by mass spectrometry and turbine and vastus lateralis [HHb] measured by near-infrared spectroscopy were recorded throughout. Arterialized-capillary lactate concentration ([Lac - ]) was obtained before and 2 min postexercise. The τV̇o 2p was lowest ( P 0.05) between conditions. Postexercise [Lac - ] was lowest ( P exercise speeded V̇o 2p kinetics and reduced overall V̇o 2p , suggesting an increased reliance on PCr-derived phosphorylation during the work period of INT compared with an identical PO performed continuously. NEW & NOTEWORTHY We report novel observations on the effects of differing heavy-intensity work durations between 3-s recovery periods on pulmonary oxygen uptake (V̇o 2p ) kinetics, muscle deoxygenation, and energy system contributions. Relative to continuous exercise, V̇o 2p kinetics are faster in intermittent exercise, and increased frequency of 3-s recovery periods improves microvascular O 2 delivery and reduces V̇o 2p and arterialized-capillary lactate concentration. The metabolic burden of identical intensity work is altered when performed intermittently vs. continuously. Copyright

  1. In vivo measurements of T1 relaxation times of 31P-metabolites in human skeletal muscle

    DEFF Research Database (Denmark)

    Thomsen, C; Jensen, K E; Henriksen, O

    1989-01-01

    The T1 relaxation times were estimated for 31P-metabolites in human skeletal muscle. Five healthy volunteers were examined in a 1.5 Tesla wholebody imaging system using an inversion recovery pulse sequence. The calculated T1 relaxation times ranged from 5.517 sec for phosphocreatine to 3.603 sec...

  2. Both Creatine and Its Product Phosphocreatine Reduce Oxidative Stress and Afford Neuroprotection in an In Vitro Parkinson’s Model

    Directory of Open Access Journals (Sweden)

    Mauricio Peña Cunha

    2014-10-01

    Full Text Available Creatine is the substrate for creatine kinase in the synthesis of phosphocreatine (PCr. This energetic system is endowed of antioxidant and neuroprotective properties and plays a pivotal role in brain energy homeostasis. The purpose of this study was to investigate the neuroprotective effect of creatine and PCr against 6-hydroxydopamine (6-OHDA-induced mitochondrial dysfunction and cell death in rat striatal slices, used as an in vitro Parkinson’s model. The possible involvement of the signaling pathway mediated by phosphatidylinositol-3 kinase (PI3K, protein kinase B (Akt, and glycogen synthase kinase-3β (GSK3β was also evaluated. Exposure of striatal slices to 6-OHDA caused a significant disruption of the cellular homeostasis measured as 3-(4,5 dimethylthiazol-2-yl-2,5-diphenyl-tetrazolium bromide reduction, lactate dehydrogenase release, and tyrosine hydroxylase levels. 6-OHDA exposure increased the levels of reactive oxygen species and thiobarbituric acid reactive substances production and decreased mitochondrial membrane potential in rat striatal slices. Furthermore, 6-OHDA decreased the phosphorylation of Akt (Serine473 and GSK3β (Serine9. Coincubation with 6-OHDA and creatine or PCr reduced the effects of 6-OHDA toxicity. The protective effect afforded by creatine or PCr against 6-OHDA-induced toxicity was reversed by the PI3K inhibitor LY294002. In conclusion, creatine and PCr minimize oxidative stress in striatum to afford neuroprotection of dopaminergic neurons.

  3. Both Creatine and Its Product Phosphocreatine Reduce Oxidative Stress and Afford Neuroprotection in an In Vitro Parkinson’s Model

    Science.gov (United States)

    Martín-de-Saavedra, Maria D.; Romero, Alejandro; Egea, Javier; Ludka, Fabiana K.; Tasca, Carla I.; Farina, Marcelo; Rodrigues, Ana Lúcia S.; López, Manuela G.

    2014-01-01

    Creatine is the substrate for creatine kinase in the synthesis of phosphocreatine (PCr). This energetic system is endowed of antioxidant and neuroprotective properties and plays a pivotal role in brain energy homeostasis. The purpose of this study was to investigate the neuroprotective effect of creatine and PCr against 6-hydroxydopamine (6-OHDA)-induced mitochondrial dysfunction and cell death in rat striatal slices, used as an in vitro Parkinson’s model. The possible involvement of the signaling pathway mediated by phosphatidylinositol-3 kinase (PI3K), protein kinase B (Akt), and glycogen synthase kinase-3β (GSK3β) was also evaluated. Exposure of striatal slices to 6-OHDA caused a significant disruption of the cellular homeostasis measured as 3-(4,5 dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide reduction, lactate dehydrogenase release, and tyrosine hydroxylase levels. 6-OHDA exposure increased the levels of reactive oxygen species and thiobarbituric acid reactive substances production and decreased mitochondrial membrane potential in rat striatal slices. Furthermore, 6-OHDA decreased the phosphorylation of Akt (Serine473) and GSK3β (Serine9). Coincubation with 6-OHDA and creatine or PCr reduced the effects of 6-OHDA toxicity. The protective effect afforded by creatine or PCr against 6-OHDA-induced toxicity was reversed by the PI3K inhibitor LY294002. In conclusion, creatine and PCr minimize oxidative stress in striatum to afford neuroprotection of dopaminergic neurons. PMID:25424428

  4. Effects of prior heavy exercise on VO(2) kinetics during heavy exercise are related to changes in muscle activity.

    Science.gov (United States)

    Burnley, Mark; Doust, Jonathan H; Ball, Derek; Jones, Andrew M

    2002-07-01

    We hypothesized that the elevated primary O(2) uptake (VO(2)) amplitude during the second of two bouts of heavy cycle exercise would be accompanied by an increase in the integrated electromyogram (iEMG) measured from three leg muscles (gluteus maximus, vastus lateralis, and vastus medialis). Eight healthy men performed two 6-min bouts of heavy leg cycling (at 70% of the difference between the lactate threshold and peak VO(2)) separated by 12 min of recovery. The iEMG was measured throughout each exercise bout. The amplitude of the primary VO(2) response was increased after prior heavy leg exercise (from mean +/- SE 2.11 +/- 0.12 to 2.44 +/- 0.10 l/min, P exercise (491 +/- 108 vs. 604 +/- 151% increase above baseline values, P exercise is related to a greater recruitment of motor units at the onset of exercise.

  5. Effects of hypo- und hyperthyroidism on skeletal muscle metabolism. A sup 31 P magnetic resonance spectroscopy study. Einfluss von Hyper- und Hypothyreose auf den Energiestoffwechsel der Skelettmuskulatur. Eine Untersuchung mit sup 31 P-Kernspinspektroskopie

    Energy Technology Data Exchange (ETDEWEB)

    Moka, D.; Theissen, P.; Linden, A.; Waters, W.; Schicha, H. (Koeln Univ. (Germany, F.R.). Klinik und Poliklinik fuer Nuklearmedizin)

    1991-06-01

    {sup 31}P magnetic resonance spectroscopy allows non-invasive evaluation of phosphorus metabolism in man. The purpose of the present study was to assess the influence of hyper- and hypothyroidism on the metabolism of resting human skeletal muscle. The present data show that quantitative measurement of phosphate metabolism by NMR is possible as also demonstrated by other studies. Using a quantitative evaluation method with an external standard, significant differences in the levels of phosphocreatine, adenosintriphosphate, and phosphodiesters were found. In hypothyroid patients a TSH-dependent increase in phosphodiesters and a decrease in adenosintriphosphate and phosphocreatine was observed. In hyperthyroidism a similar decrease in adenosintriphosphate but a considerably higher decrease in phosphocreatine occurred. In the light of the results of other studies of muscle matabolism, these changes appear to be non-specific so that further studies are required to assess the clinical value of such measurements. (orig.).

  6. The study of the tolerance to skeletal muscle ischemia

    International Nuclear Information System (INIS)

    Tsubo, Masahiko; Takai, Hiroaki; Ikata, Takaaki; Sogabe, Takayuki; Miura, Iwao.

    1988-01-01

    A model of amputated and replanted legs were used for the study on the energy metabolism during long-period skeletal muscle ischemia. The energy metabolic changes and intracellular pH were measured continuously and non-invasively by 31 P-MRS technique. Immediately following ischemia, phosphocreatine declined and inorganic phosphate rose. However, ATP was maintained for 2 hours. During ischemia, phosphocreatine was not detected after about 3.5 hours and ATP was no longer detectable after about 5 hours. On the other hand, intracellular pH began declining linearly after 30 minutes. All cases of 4-hour ischemia and 57 % of 5-hour ischemia recovered. And all cases of 6-hour ischemia did not recover. (author)

  7. Energy conservation attenuates the loss of skeletal muscle excitability during intense contractions

    DEFF Research Database (Denmark)

    Macdonald, W A; Ørtenblad, N; Nielsen, Ole Bækgaard

    2007-01-01

    High-frequency stimulation of skeletal muscle has long been associated with ionic perturbations, resulting in the loss of membrane excitability, which may prevent action potential propagation and result in skeletal muscle fatigue. Associated with intense skeletal muscle contractions are large...... with control muscles, the resting metabolites ATP, phosphocreatine, creatine, and lactate, as well as the resting muscle excitability as measured by M-waves, were unaffected by treatment with BTS plus dantrolene. Following 20 or 30 s of continuous 60-Hz stimulation, BTS-plus-dantrolene-treated muscles showed...... changes in muscle metabolites. However, the role of metabolites in the loss of muscle excitability is not clear. The metabolic state of isolated rat extensor digitorum longus muscles at 30 degrees C was manipulated by decreasing energy expenditure and thereby allowed investigation of the effects of energy...

  8. Comparing localized and nonlocalized dynamic 31P magnetic resonance spectroscopy in exercising muscle at 7T

    Science.gov (United States)

    Meyerspeer, Martin; Robinson, Simon; Nabuurs, Christine I; Scheenen, Tom; Schoisengeier, Adrian; Unger, Ewald; Kemp, Graham J; Moser, Ewald

    2012-01-01

    By improving spatial and anatomical specificity, localized spectroscopy can enhance the power and accuracy of the quantitative analysis of cellular metabolism and bioenergetics. Localized and nonlocalized dynamic 31P magnetic resonance spectroscopy using a surface coil was compared during aerobic exercise and recovery of human calf muscle. For localization, a short echo time single-voxel magnetic resonance spectroscopy sequence with adiabatic refocusing (semi-LASER) was applied, enabling the quantification of phosphocreatine, inorganic phosphate, and pH value in a single muscle (medial gastrocnemius) in single shots (TR = 6 s). All measurements were performed in a 7 T whole body scanner with a nonmagnetic ergometer. From a series of equal exercise bouts we conclude that: (a) with localization, measured phosphocreatine declines in exercise to a lower value (79 ± 7% cf. 53 ± 10%, P = 0.002), (b) phosphocreatine recovery shows shorter half time (t1/2 = 34 ± 7 s cf. t1/2 = 42 ± 7 s, nonsignificant) and initial postexercise phosphocreatine resynthesis rate is significantly higher (32 ± 5 mM/min cf. 17 ± 4 mM/min, P = 0.001) and (c) in contrast to nonlocalized 31P magnetic resonance spectroscopy, no splitting of the inorganic phosphate peak is observed during exercise or recovery, just an increase in line width during exercise. This confirms the absence of contaminating signals originating from weaker-exercising muscle, while an observed inorganic phosphate line broadening most probably reflects variations across fibers in a single muscle. Magn Reson Med, 2012. © 2012 Wiley Periodicals, Inc. PMID:22334374

  9. Some factors determining the PCr recovery overshoot in skeletal muscle.

    Science.gov (United States)

    Korzeniewski, Bernard; Zoladz, Jerzy A

    2005-07-01

    It has been proposed recently that the phosphocreatine (PCr) overshoot (increase above the resting level) during muscle recovery after exercise is caused by a slow decay during this recovery of the direct activation of oxidative phosphorylation taking place during muscle work. In the present article the factors determining the appearance and size of the PCr overshoot are studied using the computer model of oxidative phosphorylation in intact skeletal muscle developed previously. It is demonstrated that the appearance and duration of this overshoot is positively correlated with the value of the characteristic decay time of the direct activation of oxidative phosphorylation. It is also shown that the size of PCr overshoot is increased by low resting PCr/Cr ratio (what is confirmed by our unpublished experimental data), by high intensity of the direct activation of oxidative phosphorylation, by high muscle work intensity and by low rate of the return of cytosolic pH to the resting value during muscle recovery.

  10. Evaluation of skeletal muscle during calf exercise by 31-phosphorus magnetic resonance spectroscopy in patients on statin medications.

    Science.gov (United States)

    Wu, Jim S; Buettner, Catherine; Smithline, Howard; Ngo, Long H; Greenman, Robert L

    2011-01-01

    Muscle pain is a common side effect of statin medications, but the cause is poorly understood. We characterized phosphocreatine (PCr) exercise recovery kinetics in 10 patients with hypercholesterolemia before and after a 4-week regimen of statin therapy using 31-phosphorus magnetic resonance spectroscopy ((31) P-MRS). (31) P spectra were obtained before, during, and after exercise on a calf flexion pedal ergometer. Creatine kinase (CK) serum levels were drawn before and after statin therapy. The mean metabolic recovery time constant in subjects increased from 28.1 s (SE = 6.5 s) to 55.4 s (SE = 7.4 s) after statin therapy. The unweighted mean of the pre/post-recovery time difference was -27.3 s (SE = 12.4 s; P = 0.02). Pre- and post-therapy CK levels were not significantly different (P = 0.50). Metabolic recovery time in the calf is prolonged in patients after statin use. This suggests that statins impair mitochondrial oxidative function, and (31) P MRS is a potential study model for statin-associated myopathy. Copyright © 2010 Wiley Periodicals, Inc.

  11. Evaluation of skeletal muscle during calf exercise by 31P MR spectroscopy in patients on statin medications

    Science.gov (United States)

    Buettner, Catherine; Smithline, Howard; Ngo, Long H; Greenman, Robert L.

    2012-01-01

    Introduction Muscle pain is a common side effect of statin medications, however, the cause is poorly understood. Methods We characterized phosphocreatine (PCr) exercise recovery kinetics in 10 patients with hypercholesterolemia before and after a 4 week regimen of statin therapy using 31P magnetic resonance spectroscopy (31P-MRS). 31P spectra were obtained before, during, and following exercise on a calf flexion pedal ergometer. Creatine kinase (CK) serum levels were drawn before and after statin therapy. Results The mean metabolic recovery time constant in subjects increased from 28.1s (SE=6.5s) to 55.4s (SE=7.4s) following statin therapy. The unweighted mean of the pre-post recovery time difference was -27.3s (SE=12.4s); (p-value = 0.02). Pre- and post-therapy CK levels were not significantly different (p-value = 0.50). Discussion Metabolic recovery time in the calf is prolonged in patients following statin use. This suggests that statins impair mitochondrial oxidative function, and 31P –MRS is a potential study model for statin-associated myopathy. PMID:21171098

  12. A study of fatigue in rabbit skeletal muscle by in vivo 31P MRS

    International Nuclear Information System (INIS)

    Koga, Keiko; Miura, Iwao

    1989-01-01

    Energy metabolism during exercise and recovery process of rabbit skeletal muscle was obserbed by in vivo 31 P MRS. The small value of the ratio of the intensities between inorganic phosphate and phosphocreatine at rest indicated that the observed moiety of muscle had high fast-twitch fiber content. More than half of ATP and almost all of phosphocreatine were depleted by electric stimulation at 4Hz. The extreme intracellular pH was 5.9. The recovery from this metabolic state was very slow, and only a small amount of ATP was resynthesized after 40 minutes of recovery. These phenomena show the characteristic features of the energy metabolism in the fatigue of fast-twitch muscle. The metabolic state as indicated by the intensity of phosphocreatine and intracellular pH during exercise was not always parallel to contraction power measured by straingauge. Two inorganic phosphate peaks were observed, which are regarded as the signals from fast-twitch fiber and slow-twitch fiber from their pH values. The ratios of these two peaks were different between 1Hz, 2Hz, and 4Hz electric stimulation. We conclude that we are observing the different recruitment of fiber types at different exercise level in vivo. (author)

  13. Incubating Isolated Mouse EDL Muscles with Creatine Improves Force Production and Twitch Kinetics in Fatigue Due to Reduction in Ionic Strength

    Science.gov (United States)

    Head, Stewart I.; Greenaway, Bronwen; Chan, Stephen

    2011-01-01

    Background Creatine supplementation can improve performance during high intensity exercise in humans and improve muscle strength in certain myopathies. In this present study, we investigated the direct effects of acute creatine incubation on isolated mouse fast-twitch EDL muscles, and examined how these effects change with fatigue. Methods and Results The extensor digitorum longus muscle from mice aged 12–14 weeks was isolated and stimulated with field electrodes to measure force characteristics in 3 different states: (i) before fatigue; (ii) immediately after a fatigue protocol; and (iii) after recovery. These served as the control measurements for the muscle. The muscle was then incubated in a creatine solution and washed. The measurement of force characteristics in the 3 different states was then repeated. In un-fatigued muscle, creatine incubation increased the maximal tetanic force. In fatigued muscle, creatine treatment increased the force produced at all frequencies of stimulation. Incubation also increased the rate of twitch relaxation and twitch contraction in fatigued muscle. During repetitive fatiguing stimulation, creatine-treated muscles took 55.1±9.5% longer than control muscles to lose half of their original force. Measurement of weight changes showed that creatine incubation increased EDL muscle mass by 7%. Conclusion Acute creatine application improves force production in isolated fast-twitch EDL muscle, and these improvements are particularly apparent when the muscle is fatigued. One likely mechanism for this improvement is an increase in Ca2+ sensitivity of contractile proteins as a result of ionic strength decreases following creatine incubation. PMID:21850234

  14. Incubating isolated mouse EDL muscles with creatine improves force production and twitch kinetics in fatigue due to reduction in ionic strength.

    Directory of Open Access Journals (Sweden)

    Stewart I Head

    Full Text Available BACKGROUND: Creatine supplementation can improve performance during high intensity exercise in humans and improve muscle strength in certain myopathies. In this present study, we investigated the direct effects of acute creatine incubation on isolated mouse fast-twitch EDL muscles, and examined how these effects change with fatigue. METHODS AND RESULTS: The extensor digitorum longus muscle from mice aged 12-14 weeks was isolated and stimulated with field electrodes to measure force characteristics in 3 different states: (i before fatigue; (ii immediately after a fatigue protocol; and (iii after recovery. These served as the control measurements for the muscle. The muscle was then incubated in a creatine solution and washed. The measurement of force characteristics in the 3 different states was then repeated. In un-fatigued muscle, creatine incubation increased the maximal tetanic force. In fatigued muscle, creatine treatment increased the force produced at all frequencies of stimulation. Incubation also increased the rate of twitch relaxation and twitch contraction in fatigued muscle. During repetitive fatiguing stimulation, creatine-treated muscles took 55.1±9.5% longer than control muscles to lose half of their original force. Measurement of weight changes showed that creatine incubation increased EDL muscle mass by 7%. CONCLUSION: Acute creatine application improves force production in isolated fast-twitch EDL muscle, and these improvements are particularly apparent when the muscle is fatigued. One likely mechanism for this improvement is an increase in Ca(2+ sensitivity of contractile proteins as a result of ionic strength decreases following creatine incubation.

  15. Application of the principles of systems biology and Wiener's cybernetics for analysis of regulation of energy fluxes in muscle cells in vivo.

    Science.gov (United States)

    Guzun, Rita; Saks, Valdur

    2010-03-08

    The mechanisms of regulation of respiration and energy fluxes in the cells are analyzed based on the concepts of systems biology, non-equilibrium steady state kinetics and applications of Wiener's cybernetic principles of feedback regulation. Under physiological conditions cardiac function is governed by the Frank-Starling law and the main metabolic characteristic of cardiac muscle cells is metabolic homeostasis, when both workload and respiration rate can be changed manifold at constant intracellular level of phosphocreatine and ATP in the cells. This is not observed in skeletal muscles. Controversies in theoretical explanations of these observations are analyzed. Experimental studies of permeabilized fibers from human skeletal muscle vastus lateralis and adult rat cardiomyocytes showed that the respiration rate is always an apparent hyperbolic but not a sigmoid function of ADP concentration. It is our conclusion that realistic explanations of regulation of energy fluxes in muscle cells require systemic approaches including application of the feedback theory of Wiener's cybernetics in combination with detailed experimental research. Such an analysis reveals the importance of limited permeability of mitochondrial outer membrane for ADP due to interactions of mitochondria with cytoskeleton resulting in quasi-linear dependence of respiration rate on amplitude of cyclic changes in cytoplasmic ADP concentrations. The system of compartmentalized creatine kinase (CK) isoenzymes functionally coupled to ANT and ATPases, and mitochondrial-cytoskeletal interactions separate energy fluxes (mass and energy transfer) from signalling (information transfer) within dissipative metabolic structures - intracellular energetic units (ICEU). Due to the non-equilibrium state of CK reactions, intracellular ATP utilization and mitochondrial ATP regeneration are interconnected by the PCr flux from mitochondria. The feedback regulation of respiration occurring via cyclic fluctuations of

  16. Effects of intra-arterial epinephrine on energy metabolism in exercising rabbit gastrocnemius muscle, studied by in vivo phosphorus nuclear magnetic resonance.

    Science.gov (United States)

    Argov, Z; Nioka, S; Eleff, S; Chance, B

    1991-10-01

    Epinephrine has an inotropic effect on skeletal muscle, especially on glycolytic type 2 fibers. The mechanism of this effect is not completely clear and its association with a change in oxidative metabolism or glycolytic activation was not fully investigated. Epinephrine's effects on muscle bioenergetics were studied by in vivo 31P nuclear magnetic resonance to find if mitochondrial metabolism is changed during the inotropic action and if the known glycolytic activation by epinephrine is operative during muscle twitch. The study was also used as a model for the application of in vivo 31P nuclear magnetic resonance in the evaluation of short-term acting drugs. When injected intra-arterially, epinephrine (1 micrograms/kg) augmented the twitch tension of indirectly stimulated, continuously working rabbit gastrocnemius muscle by 15.4 + 6.5%. This increase in work was associated with reduction of phosphocreatine to inorganic phosphate ratio (PCr/Pi) from 3.4 to 2.1 without change in ATP levels. Intracellular pH was reduced from 6.9 to 6.75, but no accumulation of glycolytic intermediates could be observed. The increase in work was not associated with a rise in ADP. All these changes occurred for a few minutes only. The findings suggest that epinephrine's inotropic action is not mediated by a change in mitochondrial metabolism. Glycolytic activation by epinephrine occurs even during twitch and contributes partly to the energy demands of the augmented force. Epinephrine's inotropic effect is, however, not primarily due to changes in bioenergetic kinetics, but to effects on force generating mechanisms, with secondary reduction in energy state.

  17. Application of the Principles of Systems Biology and Wiener’s Cybernetics for Analysis of Regulation of Energy Fluxes in Muscle Cells in Vivo

    Science.gov (United States)

    Guzun, Rita; Saks, Valdur

    2010-01-01

    The mechanisms of regulation of respiration and energy fluxes in the cells are analyzed based on the concepts of systems biology, non-equilibrium steady state kinetics and applications of Wiener’s cybernetic principles of feedback regulation. Under physiological conditions cardiac function is governed by the Frank-Starling law and the main metabolic characteristic of cardiac muscle cells is metabolic homeostasis, when both workload and respiration rate can be changed manifold at constant intracellular level of phosphocreatine and ATP in the cells. This is not observed in skeletal muscles. Controversies in theoretical explanations of these observations are analyzed. Experimental studies of permeabilized fibers from human skeletal muscle vastus lateralis and adult rat cardiomyocytes showed that the respiration rate is always an apparent hyperbolic but not a sigmoid function of ADP concentration. It is our conclusion that realistic explanations of regulation of energy fluxes in muscle cells require systemic approaches including application of the feedback theory of Wiener’s cybernetics in combination with detailed experimental research. Such an analysis reveals the importance of limited permeability of mitochondrial outer membrane for ADP due to interactions of mitochondria with cytoskeleton resulting in quasi-linear dependence of respiration rate on amplitude of cyclic changes in cytoplasmic ADP concentrations. The system of compartmentalized creatine kinase (CK) isoenzymes functionally coupled to ANT and ATPases, and mitochondrial-cytoskeletal interactions separate energy fluxes (mass and energy transfer) from signalling (information transfer) within dissipative metabolic structures – intracellular energetic units (ICEU). Due to the non-equilibrium state of CK reactions, intracellular ATP utilization and mitochondrial ATP regeneration are interconnected by the PCr flux from mitochondria. The feedback regulation of respiration occurring via cyclic fluctuations

  18. Similar mitochondrial activation kinetics in wild-type and creatine kinase-deficient fast-twitch muscle indicate significant Pi control of respiration

    NARCIS (Netherlands)

    Jeneson, J.A.L.; Veld, ter F.; Schmitz, J.P.J.; Meyer, R.A.; Hilbers, P.A.J.; Nicolay, K.

    2011-01-01

    Past simulations of oxidative ATP metabolism in skeletal muscle have predicted that elimination of the creatine kinase (CK) reaction should result in dramatically faster oxygen consumption dynamics during transitions in ATP turnover rate. This hypothesis was investigated. Oxygen consumption of

  19. The effects of methylmercury on the mitochondrial energetics of rat skeletal muscle

    International Nuclear Information System (INIS)

    Kuwabara, Takeo; Yuasa, Tatsuhiko; Nagashima, Masaru; Igarashi, Hironaka; Yonemochi, Yousuke; Atsumi, Tetsushi; Miyatake, Tadashi

    1989-01-01

    In this report it is shown that methylmercury chloride (MMC) affected the mitochondrial energetics of rat skeletal muscles in case of chronic intoxication. High energy phosphate compounds were measured by 31 P-NMR spectroscopy in the living rat hindleg skeletal muscle. Decreased value of phosphocreatine (PCr)/inorganic phosphate (Pi) ratio was observed in the resting muscle of the MMC intoxicated group, and suspend recovery of the ATP, PCr and intracellular pH after muscle contraction was found in the MMC intoxicated muscle. There was no difference in the ATP levels of the resting muscle between the control and MMC group. These results suggested that the synthesis of ATP was disturbed by the inhibition of mitochondrial respiration below TCA cycle. (author)

  20. Application of 31P MR spectroscopy to the study of skeletal muscles in man

    International Nuclear Information System (INIS)

    Hajek, M.; Horska, A.; Belan, A.; Taborsky, P.; Grosmanova, A.

    1990-01-01

    The potential of in vivo magnetic resonance spectroscopy in clinical practice is discussed. The principles of in vivo technique are outlined, the present state is characterized, and a survey of applications of the magnetic resonance of the quiescent skeletal muscle is presented. The phosphocreatine-to-inorganic phosphate signal ratios were evaluated for a cohort of patients with neuromuscular metabolic diseases, a cohort of patients with chronic renal insufficiency, and a control cohort. Statistically significant differences were found between the groups of patients and the control. The difference between the spectra of normal skeletal muscles with benign tumors is also discussed. (author). 5 figs., 6 tabs., 28 refs

  1. Wortmannin inhibits both insulin- and contraction-stimulated glucose uptake and transport in rat skeletal muscle

    DEFF Research Database (Denmark)

    Wojtaszewski, Jørgen; Hansen, B F; Ursø, Birgitte

    1996-01-01

    The role of phosphatidylinositol (PI) 3-kinase for insulin- and contraction-stimulated muscle glucose transport was investigated in rat skeletal muscle perfused with a cell-free perfusate. The insulin receptor substrate-1-associated PI 3-kinase activity was increased sixfold upon insulin...... stimulation but was unaffected by contractions. In addition, the insulin-stimulated PI 3-kinase activity and muscle glucose uptake and transport in individual muscles were dose-dependently inhibited by wortmannin with one-half maximal inhibition values of approximately 10 nM and total inhibition at 1 micro......M. This concentration of wortmannin also decreased the contraction-stimulated glucose transport and uptake by approximately 30-70% without confounding effects on contractility or on muscle ATP and phosphocreatine concentrations. At higher concentrations (3 and 10 microM), wortmannin completely blocked the contraction...

  2. A Drosophila model of dominant inclusion body myopathy type 3 shows diminished myosin kinetics that reduce muscle power and yield myofibrillar defects.

    Science.gov (United States)

    Suggs, Jennifer A; Melkani, Girish C; Glasheen, Bernadette M; Detor, Mia M; Melkani, Anju; Marsan, Nathan P; Swank, Douglas M; Bernstein, Sanford I

    2017-06-01

    Individuals with inclusion body myopathy type 3 (IBM3) display congenital joint contractures with early-onset muscle weakness that becomes more severe in adulthood. The disease arises from an autosomal dominant point mutation causing an E706K substitution in myosin heavy chain type IIa. We have previously expressed the corresponding myosin mutation (E701K) in homozygous Drosophila indirect flight muscles and recapitulated the myofibrillar degeneration and inclusion bodies observed in the human disease. We have also found that purified E701K myosin has dramatically reduced actin-sliding velocity and ATPase levels. Since IBM3 is a dominant condition, we now examine the disease state in heterozygote Drosophila in order to gain a mechanistic understanding of E701K pathogenicity. Myosin ATPase activities in heterozygotes suggest that approximately equimolar levels of myosin accumulate from each allele. In vitro actin sliding velocity rates for myosin isolated from the heterozygotes were lower than the control, but higher than for the pure mutant isoform. Although sarcomeric ultrastructure was nearly wild type in young adults, mechanical analysis of skinned indirect flight muscle fibers revealed a 59% decrease in maximum oscillatory power generation and an approximately 20% reduction in the frequency at which maximum power was produced. Rate constant analyses suggest a decrease in the rate of myosin attachment to actin, with myosin spending decreased time in the strongly bound state. These mechanical alterations result in a one-third decrease in wing beat frequency and marginal flight ability. With aging, muscle ultrastructure and function progressively declined. Aged myofibrils showed Z-line streaming, consistent with the human heterozygote phenotype. Based upon the mechanical studies, we hypothesize that the mutation decreases the probability of the power stroke occurring and/or alters the degree of movement of the myosin lever arm, resulting in decreased in vitro

  3. A Drosophila model of dominant inclusion body myopathy type 3 shows diminished myosin kinetics that reduce muscle power and yield myofibrillar defects

    Directory of Open Access Journals (Sweden)

    Jennifer A. Suggs

    2017-06-01

    Full Text Available Individuals with inclusion body myopathy type 3 (IBM3 display congenital joint contractures with early-onset muscle weakness that becomes more severe in adulthood. The disease arises from an autosomal dominant point mutation causing an E706K substitution in myosin heavy chain type IIa. We have previously expressed the corresponding myosin mutation (E701K in homozygous Drosophila indirect flight muscles and recapitulated the myofibrillar degeneration and inclusion bodies observed in the human disease. We have also found that purified E701K myosin has dramatically reduced actin-sliding velocity and ATPase levels. Since IBM3 is a dominant condition, we now examine the disease state in heterozygote Drosophila in order to gain a mechanistic understanding of E701K pathogenicity. Myosin ATPase activities in heterozygotes suggest that approximately equimolar levels of myosin accumulate from each allele. In vitro actin sliding velocity rates for myosin isolated from the heterozygotes were lower than the control, but higher than for the pure mutant isoform. Although sarcomeric ultrastructure was nearly wild type in young adults, mechanical analysis of skinned indirect flight muscle fibers revealed a 59% decrease in maximum oscillatory power generation and an approximately 20% reduction in the frequency at which maximum power was produced. Rate constant analyses suggest a decrease in the rate of myosin attachment to actin, with myosin spending decreased time in the strongly bound state. These mechanical alterations result in a one-third decrease in wing beat frequency and marginal flight ability. With aging, muscle ultrastructure and function progressively declined. Aged myofibrils showed Z-line streaming, consistent with the human heterozygote phenotype. Based upon the mechanical studies, we hypothesize that the mutation decreases the probability of the power stroke occurring and/or alters the degree of movement of the myosin lever arm, resulting in

  4. In vivo relaxation of N-acetyl-aspartate, creatine plus phosphocreatine, and choline containing compounds during the course of brain infarction: a proton MRS study

    DEFF Research Database (Denmark)

    Gideon, P; Henriksen, O

    1992-01-01

    Localized water suppressed proton spectroscopy has opened up a new field of pathophysiological studies of severe brain ischemia. The signals obtained with the pulse sequences used so far are both T1 and T2 weighted. In order to evaluate the extent to which changes in metabolite signals during...... the course of infarction can be explained by changes in T1 and T2 relaxation times, eight patients with acute stroke were studied. STEAM sequences with varying echo delay times and repetition times were used to measure T1 and T2 of N-acetyl-aspartate (NAA), creatine plus phosphocreatine (Cr+PCr) and choline...... containing compounds (CHO) in a 27-ml voxel located in the affected area of the brain. Ten healthy volunteers served as controls. We found no difference in T1 or T2 of the metabolites between the patients and the normal controls. The T2 of CHO was longer than that of NAA and Cr+PCr. Our results indicate...

  5. Unchanged content of oxidative enzymes in fast-twitch muscle fibers and V˙O2 kinetics after intensified training in trained cyclists

    DEFF Research Database (Denmark)

    Christensen, Peter Møller; Gunnarsson, Thomas Gunnar Petursson; Thomassen, Martin

    2015-01-01

    perturbation during INT. Pulmonary V˙O2 kinetics was determined in eight trained male cyclists (V˙O2-max: 59 ± 4 (means ± SD) mL min(-1) kg(-1)) during MOD (205 ± 12 W ~65% V˙O2-max) and INT (286 ± 17 W ~85% V˙O2-max) exercise before and after a 7-week HIT period (30-sec sprints and 4-min intervals) with a 50...... DW(-1) min(-1)) of CS (56 ± 8 post-HIT vs. 59 ± 10 pre-HIT), HAD (27 ± 6 vs. 29 ± 3) and PFK (340 ± 69 vs. 318 ± 105) and the capillary to fiber ratio (2.30 ± 0.16 vs. 2.38 ± 0.20) was unaltered following HIT. V˙O2 kinetics was unchanged with HIT and the speed of the primary response did not differ...... of oxidative enzymes in fast-twitch fibers, and did not change V˙O2 kinetics....

  6. Administration of exercise-conditioned plasma alters muscle catalase kinetics in rat: An argument for in vivo-like Km instead of in vitro-like Vmax

    Directory of Open Access Journals (Sweden)

    Aristidis S. Veskoukis

    2018-05-01

    Full Text Available Maximal velocity (Vmax is a well established biomarker for the assessment of tissue redox status. There is scarce evidence, though, that it does not probably reflect sufficiently in vivo tissue redox profile. Instead, the Michaelis constant (Km could more adequately image tissue oxidative stress and, thus, be a more physiologically relevant redox biomarker. Therefore, the aim of the present study was to side-by-side compare Vmax and Km of an antioxidant enzyme after implementing an in vivo set up that induces alterations in tissue redox status. Forty rats were divided into two groups including rats injected with blood plasma originating from rats that had previously swam until exhaustion and rats injected with blood plasma originating from sedentary rats. Tail-vein injections were performed daily for 21 days. Catalase Vmax and Km measured in gastrocnemius muscle were increased after administration of the exercise-conditioned plasma, denoting enhancement of the enzyme activity but impairment of its affinity for the substrate, respectively. These alterations are potential adaptations stimulated by the administered plasma pointing out that blood is an active fluid capable of regulating tissue homeostasis. Our findings suggest that Km adequately reflects in vivo modifications of skeletal muscle catalase and seems to surpass Vmax regarding its physiological relevance and biological interpretation. In conclusion, Km can be regarded as an in vivo-like biomarker that satisfactorily images the intracellular environment, as compared to Vmax that could be aptly parallelized with a biomarker that describes tissue oxidative stress in an in vitro manner.

  7. Administration of exercise-conditioned plasma alters muscle catalase kinetics in rat: An argument for in vivo-like Km instead of in vitro-like Vmax.

    Science.gov (United States)

    Veskoukis, Aristidis S; Paschalis, Vassilis; Kyparos, Antonios; Nikolaidis, Michalis G

    2018-05-01

    Maximal velocity (V max ) is a well established biomarker for the assessment of tissue redox status. There is scarce evidence, though, that it does not probably reflect sufficiently in vivo tissue redox profile. Instead, the Michaelis constant (K m ) could more adequately image tissue oxidative stress and, thus, be a more physiologically relevant redox biomarker. Therefore, the aim of the present study was to side-by-side compare V max and K m of an antioxidant enzyme after implementing an in vivo set up that induces alterations in tissue redox status. Forty rats were divided into two groups including rats injected with blood plasma originating from rats that had previously swam until exhaustion and rats injected with blood plasma originating from sedentary rats. Tail-vein injections were performed daily for 21 days. Catalase V max and K m measured in gastrocnemius muscle were increased after administration of the exercise-conditioned plasma, denoting enhancement of the enzyme activity but impairment of its affinity for the substrate, respectively. These alterations are potential adaptations stimulated by the administered plasma pointing out that blood is an active fluid capable of regulating tissue homeostasis. Our findings suggest that K m adequately reflects in vivo modifications of skeletal muscle catalase and seems to surpass V max regarding its physiological relevance and biological interpretation. In conclusion, K m can be regarded as an in vivo-like biomarker that satisfactorily images the intracellular environment, as compared to V max that could be aptly parallelized with a biomarker that describes tissue oxidative stress in an in vitro manner. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

  8. Ins(1,4,5)P{sub 3} facilitates ATP accumulation via phosphocreatine/creatine kinase in the endoplasmic reticulum extracted from MDCK cells

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Jing [Medical Research Center, School of Medicine, Fukuoka University, Fukuoka 814-0180 (Japan); Department of Dental Implantology, School of Stomatology, Tongji University, Shanghai 200072 (China); Ogata, Shigenori [Joint Laboratory for Frontier Medical Science, School of Medicine, Fukuoka University, Fukuoka 814-0180 (Japan); Segawa, Masaru [Central Laboratory for Pathology and Morphology, School of Medicine, Fukuoka University, Fukuoka 814-0180 (Japan); Usune, Sadaharu [Research Laboratory of Biodynamics, School of Medicine, Fukuoka University, Fukuoka 814-0180 (Japan); Zhao, Yumei [Department of Pediatric Dentistry, School of Dentistry of Shanghai Tongji University, Shanghai 200072 (China); Katsuragi, Takeshi, E-mail: katsurag@fukuoka-u.ac.jp [Medical Research Center, School of Medicine, Fukuoka University, Fukuoka 814-0180 (Japan)

    2010-07-02

    So far, the content and accumulation of ATP in isolated endoplasmic reticulum (ER) are little understood. First, we confirmed using electron microscopic and Western blotting techniques that the samples extracted from MDCK cells are endoplasmic reticulum (ER). The amounts of ATP in the extracted ER were measured from the filtrate after a spinning down of ultrafiltration spin column packed with ER. When the ER sample (5 {mu}g) after 3 days freezing was suspended in intracellular medium (ICM), 0.1% Triton X and ultrapure water (UPW), ATP amounts from the ER with UPW were the highest and over 10 times compared with that from the control with ICM, indicating that UPW is the most effective tool in destroying the ER membrane. After a 10-min-incubation with ICM containing phosphocreatine (PCr)/creatine kinase (CK) of the fresh ER. ATP amounts in the filtrate obtained by spinning down were not changed from that in the control (no PCr/CK). However, ATP amounts in the filtrate from the second spinning down of the ER (treated with PCr/CK) suspended in UPW became over 10-fold compared with the control. When 1 {mu}M inositol(1,4,5)trisphosphate (Ins(1,4,5)P{sub 3}) was added in the incubation medium (ICM with PCr/CK), ATP amounts from the filtrate after the second spinning down were further enhanced around three times. This enhancement was almost canceled by Ca{sup 2+}-removal from ICM and by adding thapsigargin, a Ca{sup 2+}-ATPase inhibitor, but not by 2-APB and heparin, Ins(1,4,5)P{sub 3} receptor antagonists. Administration of 500 {mu}M adenosine to the incubation medium (with PCr/CK) failed to enhance the accumulation of ATP in the ER. These findings suggest that the ER originally contains ATP and ATP accumulation in the ER is promoted by PCr/CK and Ins(1,4,5)P{sub 3}.

  9. Thermodynamics of the hydrolysis reactions of α-D-galactose 1-phosphate, sn-glycerol 3-phosphate, 4-nitrophenyl phosphate, phosphocreatine, and 3-phospho-D-glycerate

    International Nuclear Information System (INIS)

    Goldberg, Robert N.; Lang, Brian E.; Lo, Catherine; Ross, David J.; Tewari, Yadu B.

    2009-01-01

    Microcalorimetry, high-performance liquid chromatography (h.p.l.c.), and an enzymatic assay have been used to conduct a thermodynamic investigation of five phosphate hydrolysis reactions: {α-D-galactose 1-phosphate(aq) + H 2 O(l) = D-galactose(aq) + orthophosphate(aq)} (1), {sn-glycerol 3-phosphate(aq) + H 2 O(l) = glycerol(aq) + orthophosphate(aq)} (2), {4-nitrophenyl phosphate(aq) + H 2 O(l) = 4-nitrophenol(aq) + orthophosphate(aq)} (3), {phosphocreatine(aq) + H 2 O(l) = creatine(aq) + orthophosphate(aq)} (4), and {3-phospho-D-glycerate(aq) + H 2 O(l) = D-glycerate(aq) + orthophosphate(aq)} (5). Calorimetrically determined enthalpies of reaction Δ r H(cal) were measured for reactions (1)-(5) and the apparent equilibrium constant K' was measured for reaction (2). The pKs and standard enthalpies of reaction Δ r H 0 for the H + and Mg 2+ binding reactions of the reactants and products in the aforementioned reactions were obtained either from the literature or by estimation. A chemical equilibrium model was then used to calculate standard equilibrium constants K and standard enthalpies of reaction Δ r H 0 for chemical reference reactions that correspond to the overall biochemical reactions that were studied experimentally. Property values from the literature and thermodynamic network calculations were used to obtain values of the equilibrium constants for the chemical reference reactions that correspond to the overall biochemical reactions (1). These values were compared with other results from the literature and also correlated with structural features. The results obtained in this study can be used in the chemical equilibrium model to calculate values of K', the standard apparent Gibbs free energy changes Δ r G '0 , the standard apparent enthalpy changes Δ r H '0 , changes in binding of the proton Δ r N(H + ), and the position of equilibrium for the overall biochemical reactions considered in this study over a reasonably wide range of temperature, pH, p

  10. Kinetic Typography

    DEFF Research Database (Denmark)

    van Leeuwen, Theo; Djonov, Emilia

    2014-01-01

    After discussing broad cultural drivers behind the development of kinetic typography, the chapter outlines an approach to analysing kinetic typography which is based on Halliday's theory of transitivity, as applied by Kress and Van Leeuwen to visual images.......After discussing broad cultural drivers behind the development of kinetic typography, the chapter outlines an approach to analysing kinetic typography which is based on Halliday's theory of transitivity, as applied by Kress and Van Leeuwen to visual images....

  11. Muscle Deoxygenation Causes Muscle Fatigue

    Science.gov (United States)

    Murthy, G.; Hargens, A. R.; Lehman, S.; Rempel, D.

    1999-01-01

    Muscle fatigue is a common musculoskeletal disorder in the work place, and may be a harbinger for more disabling cumulative trauma disorders. Although the cause of fatigue is multifactorial, reduced blood flow and muscle oxygenation may be the primary factor in causing muscle fatigue during low intensity muscle exertion. Muscle fatigue is defined as a reduction in muscle force production, and also occurs among astronauts who are subjected to postural constraints while performing lengthy, repetitive tasks. The objectives of this research are to: 1) develop an objective tool to study the role of decreased muscle oxygenation on muscle force production, and 2) to evaluate muscle fatigue during prolonged glovebox work.

  12. Muscle Cramps

    Science.gov (United States)

    ... Talk to your provider about the risks and benefits of medicines. How can I prevent muscle cramps? To prevent muscle cramps, you can Stretch your muscles, especially before exercising. If you often get leg cramps at night, ...

  13. Glycolysis in contracting rat skeletal muscle is controlled by factors related to energy state

    DEFF Research Database (Denmark)

    Ørtenblad, Niels; Macdonald, Will A; Sahlin, Kent

    2009-01-01

    The control of glycolysis in contracting muscle is not fully understood. The aim of the present study was to examine whether activation of glycolysis is mediated by factors related to the energy state or by a direct effect of Ca2+ on the regulating enzymes. Extensor digitorum longus muscles from...... and 58% of those in Con respectively. Glycolytic rate in BTS was only 51% of that in Con but the relative contribution of ATP derived from PCr (phosphocreatine) and glycolysis and the relation between muscle contents of PCr and Lac (lactate) were not different. Prolonged cyanide incubation of quiescent...... contribution of energy delivered from PCr and glycolysis during both conditions suggests that the glycolytic rate is controlled by factors related to energy state....

  14. Dynamic 31P-MR-spectroscopy of the quadriceps muscle. Influence of sex and age on spectroscopic results

    International Nuclear Information System (INIS)

    Schunk, K.; Romaneehsen, B.; Kessler, S.; Schadmand-Fischer, S.; Thelen, M.

    1999-01-01

    Purpose: 31 P-MRS is used to assess the influence of sex and age on quadriceps muscle metabolism before and after exercise. Materials and Methods: 32 healthy volunteers (15 women, 17 men; mean age: 38±17 yrs.) were examined by dynamic phosphorus-31 ( 31 P) magnetic resonance spectroscopy (MRS). In the magnet, the quadriceps muscle was stressed by an isometric and an isotonic form of exercise until exhaustion, respectively. Results: Resting conditions: With increasing subjects' age, the ratio β-adenosine triphosphate/total phosphate decreased (r=-0.37; p=0.02). With increasing subjects' age, the ratios inorganic phosphate/phosphocreatine (r=0.79; p=5x10 -8 ), phosphomonoester/β-adenosine triphosphate (r=0.74; p=10 -6 ) and phosphodiester/β-adenosine triphosphate (r=0.62; p=10 -4 ) increased. The pH was the only one of the evaluated spectroscopic parameters which showed a sex-dependence: Female subjects had a significantly lower pH (7.03±0.02) than male subjects (7.05±0.03; p=0,01). Exercise: With increasing age, the maxima of inorganic phosphate/phosphocreatine were less extreme during both of the exercises (r=-0.42; p=0.0005). Likewise, the exercise-induced acidosis was less severe with increasing age (r=0.53; p=6x10 -6 ). After the end of the exercise, the times of half recovery of inorganic phosphate/phosphocreatine and the pH correlated neither with the subjects' age nor with sex or cross-sectional area of the quadriceps muscle. Conclusion: Sex and age of volunteers affect spectroscopic results. This influence has to be considered in the interpretation of spectroscopic studies. (orig.) [de

  15. Some parameters of radionuclide kinetics

    International Nuclear Information System (INIS)

    Prokof'ev, O.N.; Smirnov, V.A.; Belen'kij, E.I.

    1978-01-01

    Numerical values of the rates of radionuclide absorption into, and elimination from, bovine organs were determined. Kinetic rate constants of radionuclides such as 89 Sr, 99 Mo, 131 I, 132 Tl, and 140 Be were calculated. The calculations were done for muscle, liver, and kidney

  16. Salting kinetics and salt diffusivities in farmed Pantanal caiman muscle Cinética de salga e difusividades de sal em carne de jacaré do Pantanal criado em cativeiro

    Directory of Open Access Journals (Sweden)

    Vânia Regina Nicoletti Telis

    2003-04-01

    Full Text Available The legal Pantanal caiman (Caiman crocodilus yacare farming, in Brazil, has been stimulated and among meat preservation techniques the salting process is a relatively simple and low-cost method. The objective of this work was to study the sodium chloride diffusion kinetics in farmed caiman muscle during salting. Limited volumes of brine were employed, with salting essays carried at 3, 4 and 5 brine/muscle ratios, at 15%, 20% and 25% w/w brine concentrations, and brine temperatures of 10, 15 and 20ºC. The analytical solution of second Fick's law considering one-dimensional diffusion through an infinite slab in contact with a well-stirred solution of limited volume was used to calculate effective salt diffusion coefficients and to predict the sodium chloride content in the fillets. A good agreement was obtained between the considered analytical model and experimental data. Salt diffusivities in fillets were found to be in the range of 0.47x10-10 to 9.62x10-10 m²/s.A criação de jacaré do Pantanal (Caiman crocodilus yacare em cativeiro tem sido estimulada, e entre as técnicas de processamento de sua carne, a salga é um processo de conservação relativamente simples e de baixo custo. O objetivo deste trabalho foi estudar a cinética de difusão de cloreto de sódio em carne de jacaré do Pantanal criado em cativeiro, durante a salga úmida. Foram utilizados volumes limitados de salmoura e os experimentos foram realizados com relações salmoura/músculo de 3, 4 e 5, com concentrações de salmoura de 15%, 20% e 25% em peso e temperaturas de 10, 15 e 20ºC. A solução analítica da segunda lei de Fick, considerando difusão unidimensional em uma placa infinita em contato com uma solução bem agitada de volume limitado, foi utilizada para calcular os coeficientes de difusão efetivos de sal e estimar o conteúdo de cloreto de sódio nos filés. Obteve-se boa concordância entre o modelo analítico considerado e os dados experimentais. As

  17. Effect of L-carnitine supplementation on the body carnitine pool, skeletal muscle energy metabolism and physical performance in male vegetarians.

    Science.gov (United States)

    Novakova, Katerina; Kummer, Oliver; Bouitbir, Jamal; Stoffel, Sonja D; Hoerler-Koerner, Ulrike; Bodmer, Michael; Roberts, Paul; Urwyler, Albert; Ehrsam, Rolf; Krähenbühl, Stephan

    2016-02-01

    More than 95% of the body carnitine is located in skeletal muscle, where it is essential for energy metabolism. Vegetarians ingest less carnitine and carnitine precursors and have lower plasma carnitine concentrations than omnivores. Principle aims of the current study were to assess the plasma and skeletal muscle carnitine content and physical performance of male vegetarians and matched omnivores under basal conditions and after L-carnitine supplementation. Sixteen vegetarians and eight omnivores participated in this interventional study with oral supplementation of 2 g L-carnitine for 12 weeks. Before carnitine supplementation, vegetarians had a 10% lower plasma carnitine concentration, but maintained skeletal muscle carnitine stores compared to omnivores. Skeletal muscle phosphocreatine, ATP, glycogen and lactate contents were also not different from omnivores. Maximal oxygen uptake (VO2max) and workload (P max) per bodyweight (bicycle spiroergometry) were not significantly different between vegetarians and omnivores. Sub-maximal exercise (75% VO2max for 1 h) revealed no significant differences between vegetarians and omnivores (respiratory exchange ratio, blood lactate and muscle metabolites). Supplementation with L-carnitine significantly increased the total plasma carnitine concentration (24% in omnivores, 31% in vegetarians) and the muscle carnitine content in vegetarians (13%). Despite this increase, P max and VO2max as well as muscle phosphocreatine, lactate and glycogen were not significantly affected by carnitine administration. Vegetarians have lower plasma carnitine concentrations, but maintained muscle carnitine stores compared to omnivores. Oral L-carnitine supplementation normalizes the plasma carnitine stores and slightly increases the skeletal muscle carnitine content in vegetarians, but without affecting muscle function and energy metabolism.

  18. Capsiate supplementation reduces oxidative cost of contraction in exercising mouse skeletal muscle in vivo.

    Science.gov (United States)

    Yashiro, Kazuya; Tonson, Anne; Pecchi, Émilie; Vilmen, Christophe; Le Fur, Yann; Bernard, Monique; Bendahan, David; Giannesini, Benoît

    2015-01-01

    Chronic administration of capsiate is known to accelerate whole-body basal energy metabolism, but the consequences in exercising skeletal muscle remain very poorly documented. In order to clarify this issue, the effect of 2-week daily administration of either vehicle (control) or purified capsiate (at 10- or 100-mg/kg body weight) on skeletal muscle function and energetics were investigated throughout a multidisciplinary approach combining in vivo and in vitro measurements in mice. Mechanical performance and energy metabolism were assessed strictly non-invasively in contracting gastrocnemius muscle using magnetic resonance (MR) imaging and 31-phosphorus MR spectroscopy (31P-MRS). Regardless of the dose, capsiate treatments markedly disturbed basal bioenergetics in vivo including intracellular pH alkalosis and decreased phosphocreatine content. Besides, capsiate administration did affect neither mitochondrial uncoupling protein-3 gene expression nor both basal and maximal oxygen consumption in isolated saponin-permeabilized fibers, but decreased by about twofold the Km of mitochondrial respiration for ADP. During a standardized in vivo fatiguing protocol (6-min of repeated maximal isometric contractions electrically induced at a frequency of 1.7 Hz), both capsiate treatments reduced oxidative cost of contraction by 30-40%, whereas force-generating capacity and fatigability were not changed. Moreover, the rate of phosphocreatine resynthesis during the post-electrostimulation recovery period remained unaffected by capsiate. Both capsiate treatments further promoted muscle mass gain, and the higher dose also reduced body weight gain and abdominal fat content. These findings demonstrate that, in addition to its anti-obesity effect, capsiate supplementation improves oxidative metabolism in exercising muscle, which strengthen this compound as a natural compound for improving health.

  19. Physical kinetics

    International Nuclear Information System (INIS)

    Lifschitz, E.M.; Pitajewski, L.P.

    1983-01-01

    The textbook covers the subject under the following headings: kinetic gas theory, diffusion approximation, collisionless plasma, collisions within the plasma, plasma in the magnetic field, theory of instabilities, dielectrics, quantum fluids, metals, diagram technique for nonequilibrium systems, superconductors, and kinetics of phase transformations

  20. Effects of physical activity and inactivity on muscle fatigue

    Directory of Open Access Journals (Sweden)

    Gregory C. Bogdanis

    2012-05-01

    Full Text Available The aim of this review was to examine the mechanisms by which physical activity and inactivity modify muscle fatigue. It is well known that acute or chronic increases in physical activity result in structural, metabolic, hormonal, neural and molecular adaptations that increase the level of force or power that can be sustained by a muscle. These adaptations depend on the type, intensity and volume of the exercise stimulus, but recent studies have highlighted the role of high intensity, short duration exercise as a time-efficient method to achieve both anaerobic and aerobic/endurance type adaptations. The factors that determine the fatigue profile of a muscle during intense exercise include muscle fibre composition, neuromuscular characteristics high energy metabolite stores, buffering capacity, ionic regulation, capillarization and mitochondrial density. Muscle fiber type transformation during exercise training is usually towards the intermediate type IIA at the expense of both type I and type IIx myosin heavy chain isoforms. High intensity training results in increases of both glycolyic and oxidative enzymes, muscle capilarization, improved phosphocreatine resynthesis and regulation of K+, H+ and lactate ions. Decreases of the habitual activity level due to injury or sedentary lifestyle result in partial or even compete reversal of the adaptations due to previous training, manifested by reductions in fibre cross-sectional area, decreased oxidative capacity and capillarization. Complete immobilization due to injury results in markedly decreased force output and fatigue resistance. Muscle unloading reduces electromyographic activity and causes muscle atrophy and significant decreases in capillarization and oxidative enzymes activity. The last part of the review discusses the beneficial effects of intermittent high intensity exercise training in patients with different health conditions to demonstrate the powerful effect exercise on health and well

  1. Heparin kinetics

    International Nuclear Information System (INIS)

    Swart, C.A.M. de.

    1983-01-01

    The author has studied the kinetics of heparin and heparin fractions after intravenous administration in humans and in this thesis the results of this study are reported. Basic knowledge about the physico-chemical properties of heparin and its interactions with proteins resulting in anticoagulant and lipolytic effects are discussed in a review (chapter II), which also comprises some clinical aspects of heparin therapy. In chapter III the kinetics of the anticoagulant effect are described after intravenous administration of five commercial heparin preparations. A mathematical model is presented that fits best to these kinetics. The kinetics of the anticoagulant and lipolytic effects after intravenous injection of various 35 S-radiolabelled heparin fractions and their relationship with the disappearance of the radiolabel are described in chapter IV. Chapter V gives a description of the kinetics of two radiolabels after injection of in vitro formed complexes consisting of purified, 125 I-radiolabelled antithrombin III and various 35 S-radiolabelled heparin fractions. (Auth.)

  2. Muscle enzyme release does not predict muscle function impairment after triathlon.

    Science.gov (United States)

    Margaritis, I; Tessier, F; Verdera, F; Bermon, S; Marconnet, P

    1999-06-01

    We sought to determine the effects of a long distance triathlon (4 km swim, 120 km bike-ride, and 30 km run) on the four-day kinetics of the biochemical markers of muscle damage, and whether they were quantitatively linked with muscle function impairment and soreness. Data were collected from 2 days before until 4 days after the completion of the race. Twelve triathletes performed the triathlon and five did not. Maximal voluntary contraction (MVC), muscle soreness (DOMS) and total serum CK, CK-MB, LDH, AST and ALT activities were assessed. Significant changes after triathlon completion were found for all muscle damage indirect markers over time (p triathlon. Long distance triathlon race caused muscle damage, but extent, as well as muscle recovery cannot be evaluated by the magnitude of changes in serum enzyme activities. Muscle enzyme release cannot be used to predict the magnitude of the muscle function impairment caused by muscle damage.

  3. Kinetic Interface

    DEFF Research Database (Denmark)

    2009-01-01

    A kinetic interface for orientation detection in a video training system is disclosed. The interface includes a balance platform instrumented with inertial motion sensors. The interface engages a participant's sense of balance in training exercises.......A kinetic interface for orientation detection in a video training system is disclosed. The interface includes a balance platform instrumented with inertial motion sensors. The interface engages a participant's sense of balance in training exercises....

  4. Skeletal muscle ATP turnover and muscle fiber conduction velocity are elevated at higher muscle temperatures during maximal power output development in humans.

    Science.gov (United States)

    Gray, Stuart R; De Vito, Giuseppe; Nimmo, Myra A; Farina, Dario; Ferguson, Richard A

    2006-02-01

    The effect of temperature on skeletal muscle ATP turnover and muscle fiber conduction velocity (MFCV) was studied during maximal power output development in humans. Eight male subjects performed a 6-s maximal sprint on a mechanically braked cycle ergometer under conditions of normal (N) and elevated muscle temperature (ET). Muscle temperature was passively elevated through the combination of hot water immersion and electric blankets. Anaerobic ATP turnover was calculated from analysis of muscle biopsies obtained before and immediately after exercise. MFCV was measured during exercise using surface electromyography. Preexercise muscle temperature was 34.2 degrees C (SD 0.6) in N and 37.5 degrees C (SD 0.6) in ET. During ET, the rate of ATP turnover for phosphocreatine utilization [temperature coefficient (Q10) = 3.8], glycolysis (Q10 = 1.7), and total anaerobic ATP turnover [Q10 = 2.7; 10.8 (SD 1.9) vs. 14.6 mmol x kg(-1) (dry mass) x s(-1) (SD 2.3)] were greater than during N (P < 0.05). MFCV was also greater in ET than in N [3.79 (SD 0.47) to 5.55 m/s (SD 0.72)]. Maximal power output (Q10 = 2.2) and pedal rate (Q10 = 1.6) were greater in ET compared with N (P < 0.05). The Q10 of maximal and mean power were correlated (P < 0.05; R = 0.82 and 0.85, respectively) with the percentage of myosin heavy chain type IIA. The greater power output obtained with passive heating was achieved through an elevated rate of anaerobic ATP turnover and MFCV, possibly due to a greater effect of temperature on power production of fibers, with a predominance of myosin heavy chain IIA at the contraction frequencies reached.

  5. Muscle Contraction.

    Science.gov (United States)

    Sweeney, H Lee; Hammers, David W

    2018-02-01

    SUMMARYMuscle cells are designed to generate force and movement. There are three types of mammalian muscles-skeletal, cardiac, and smooth. Skeletal muscles are attached to bones and move them relative to each other. Cardiac muscle comprises the heart, which pumps blood through the vasculature. Skeletal and cardiac muscles are known as striated muscles, because the filaments of actin and myosin that power their contraction are organized into repeating arrays, called sarcomeres, that have a striated microscopic appearance. Smooth muscle does not contain sarcomeres but uses the contraction of filaments of actin and myosin to constrict blood vessels and move the contents of hollow organs in the body. Here, we review the principal molecular organization of the three types of muscle and their contractile regulation through signaling mechanisms and discuss their major structural and functional similarities that hint at the possible evolutionary relationships between the cell types. Copyright © 2018 Cold Spring Harbor Laboratory Press; all rights reserved.

  6. Endurance training facilitates myoglobin desaturation during muscle contraction in rat skeletal muscle.

    Science.gov (United States)

    Takakura, Hisashi; Furuichi, Yasuro; Yamada, Tatsuya; Jue, Thomas; Ojino, Minoru; Hashimoto, Takeshi; Iwase, Satoshi; Hojo, Tatsuya; Izawa, Tetsuya; Masuda, Kazumi

    2015-03-24

    At onset of muscle contraction, myoglobin (Mb) immediately releases its bound O2 to the mitochondria. Accordingly, intracellular O2 tension (PmbO2) markedly declines in order to increase muscle O2 uptake (mVO2). However, whether the change in PmbO2 during muscle contraction modulates mVO2 and whether the O2 release rate from Mb increases in endurance-trained muscles remain unclear. The purpose of this study was, therefore, to determine the effect of endurance training on O2 saturation of Mb (SmbO2) and PmbO2 kinetics during muscle contraction. Male Wistar rats were subjected to a 4-week swimming training (Tr group; 6 days per week, 30 min × 4 sets per day) with a weight load of 2% body mass. After the training period, deoxygenated Mb kinetics during muscle contraction were measured using near-infrared spectroscopy under hemoglobin-free medium perfusion. In the Tr group, the VmO2peak significantly increased by 32%. Although the PmbO2 during muscle contraction did not affect the increased mVO2 in endurance-trained muscle, the O2 release rate from Mb increased because of the increased Mb concentration and faster decremental rate in SmbO2 at the maximal twitch tension. These results suggest that the Mb dynamics during muscle contraction are contributing factors to faster VO2 kinetics in endurance-trained muscle.

  7. Effects of branched-chain amino acids supplementation on both plasma amino acids concentration and muscle energetics changes resulting from muscle damage: A randomized placebo controlled trial.

    Science.gov (United States)

    Fouré, Alexandre; Nosaka, Kazunori; Gastaldi, Marguerite; Mattei, Jean-Pierre; Boudinet, Hélène; Guye, Maxime; Vilmen, Christophe; Le Fur, Yann; Bendahan, David; Gondin, Julien

    2016-02-01

    Branched-chain amino acids promote muscle-protein synthesis, reduce protein oxidation and have positive effects on mitochondrial biogenesis and reactive oxygen species scavenging. The purpose of the study was to determine the potential benefits of branched-chain amino acids supplementation on changes in force capacities, plasma amino acids concentration and muscle metabolic alterations after exercise-induced muscle damage. (31)P magnetic resonance spectroscopy and biochemical analyses were used to follow the changes after such damage. Twenty six young healthy men were randomly assigned to supplemented branched-chain amino acids or placebo group. Knee extensors maximal voluntary isometric force was assessed before and on four days following exercise-induced muscle damage. Concentrations in phosphocreatine [PCr], inorganic phosphate [Pi] and pH were measured during a standardized rest-exercise-recovery protocol before, two (D2) and four (D4) days after exercise-induced muscle damage. No significant difference between groups was found for changes in maximal voluntary isometric force (-24% at D2 and -21% at D4). Plasma alanine concentration significantly increased immediately after exercise-induced muscle damage (+25%) in both groups while concentrations in glycine, histidine, phenylalanine and tyrosine decreased. No difference between groups was found in the increased resting [Pi] (+42% at D2 and +34% at D4), decreased resting pH (-0.04 at D2 and -0.03 at D4) and the slower PCr recovery rate (-18% at D2 and -24% at D4). The damaged muscle was not able to get benefits out of the increased plasma branched-chain amino acids availability to attenuate changes in indirect markers of muscle damage and muscle metabolic alterations following exercise-induced muscle damage. Copyright © 2015 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.

  8. Lower Mitochondrial Energy Production of the Thigh Muscles in Patients With Low-Normal Ankle-Brachial Index.

    Science.gov (United States)

    AlGhatrif, Majd; Zane, Ariel; Oberdier, Matt; Canepa, Marco; Studenski, Stephanie; Simonsick, Eleanor; Spencer, Richard G; Fishbein, Kenneth; Reiter, David; Lakatta, Edward G; McDermott, Mary M; Ferrucci, Luigi

    2017-08-30

    Lower muscle mitochondrial energy production may contribute to impaired walking endurance in patients with peripheral arterial disease. A borderline ankle-brachial index (ABI) of 0.91 to 1.10 is associated with poorer walking endurance compared with higher ABI. We hypothesized that in the absence of peripheral arterial disease, lower ABI is associated with lower mitochondrial energy production. We examined 363 men and women participating in the Baltimore Longitudinal Study of Aging with an ABI between 0.90 and 1.40. Muscle mitochondrial energy production was assessed by post-exercise phosphocreatine recovery rate constant ( k PCr) measured by phosphorus magnetic resonance spectroscopy of the left thigh. A lower post-exercise phosphocreatine recovery rate constant reflects decreased mitochondria energy production.The mean age of the participants was 71±12 years. A total of 18.4% had diabetes mellitus and 4% were current and 40% were former smokers. Compared with participants with an ABI of 1.11 to 1.40, those with an ABI of 0.90 to 1.10 had significantly lower post-exercise phosphocreatine recovery rate constant (19.3 versus 20.8 ms -1 , P =0.015). This difference remained significant after adjusting for age, sex, race, smoking status, diabetes mellitus, body mass index, and cholesterol levels ( P =0.028). Similarly, post-exercise phosphocreatine recovery rate constant was linearly associated with ABI as a continuous variable, both in the ABI ranges of 0.90 to 1.40 (standardized coefficient=0.15, P =0.003) and 1.1 to 1.4 (standardized coefficient=0.12, P =0.0405). An ABI of 0.90 to 1.10 is associated with lower mitochondrial energy production compared with an ABI of 1.11 to 1.40. These data demonstrate adverse associations of lower ABI values with impaired mitochondrial activity even within the range of a clinically accepted definition of a normal ABI. Further study is needed to determine whether interventions in persons with ABIs of 0.90 to 1.10 can prevent

  9. Kinetics and

    Directory of Open Access Journals (Sweden)

    Mojtaba Ahmadi

    2016-11-01

    Full Text Available The aqueous degradation of Reactive Yellow 84 (RY84 by potassium peroxydisulfate (K2S2O8 has been studied in laboratory scale experiments. The effect of the initial concentrations of potassium peroxydisulfate and RY84, pH and temperature on RY84 degradation were also examined. Experimental data were analyzed using first and second-order kinetics. The degradation kinetics of RY84 of the potassium peroxydisulfate process followed the second-order reaction kinetics. These rate constants have an extreme values similar to of 9.493 mM−1min−1 at a peroxydisulfate dose of 4 mmol/L. Thermodynamic parameters such as activation (Ea and Gibbs free energy (ΔG° were also evaluated. The negative value of ΔGo and Ea shows the spontaneous reaction natural conditions and exothermic nature.

  10. Skeletal muscle abnormalities and exercise capacity in adults with a Fontan circulation.

    Science.gov (United States)

    Cordina, Rachael; O'Meagher, Shamus; Gould, Haslinda; Rae, Caroline; Kemp, Graham; Pasco, Julie A; Celermajer, David S; Singh, Nalin

    2013-10-01

    The peripheral muscle pump is key in promoting cardiac filling during exercise, especially in subjects who lack a subpulmonary ventricle (the Fontan circulation). A muscle-wasting syndrome exists in acquired heart failure but has not been assessed in Fontan subjects. We sought to investigate whether adults with the Fontan circulation exhibit reduced skeletal muscle mass and/or metabolic abnormalities. Sixteen New York Heart Association Class I/II Fontan adults (30±2 years) underwent cardiopulmonary exercise testing and lean mass quantification with dual x-ray absorptiometry (DXA); eight had calf muscle (31)P magnetic resonance spectroscopy as did eight healthy age-matched and sex-matched controls. DXA results were compared with Australian reference data. Single tertiary referral centre. Peak VO2 was 1.9±0.1 L/min (66±3% of predicted values). Skeletal muscle mass assessed by relative appendicular lean mass index was significantly reduced compared with age-matched and sex-matched reference values (Z-score -1.46±0.22, pskeletal muscle mass correlated with poorer VO2 max (r=0.67, p=0.004). Overall, skeletal muscle mass T-score (derived from comparison with young normal reference mean) was -1.47±0.21; 4/16 Fontan subjects had sarcopenic range muscle wasting (T-score Muscle aerobic capacity, measured by the rate constant (k) of postexercise phosphocreatine resynthesis, was significantly impaired in Fontan adults versus controls (1.48±0.13 vs 2.40±0.33 min(-1), p=0.02). Fontan adults have reduced skeletal muscle mass and intrinsic muscle metabolic abnormalities.

  11. Phosphorous magnetic resonance spectroscopy-based skeletal muscle bioenergetic studies in subclinical hypothyroidism.

    Science.gov (United States)

    Rana, P; Sripathy, G; Varshney, A; Kumar, P; Devi, M Memita; Marwaha, R K; Tripathi, R P; Khushu, S

    2012-02-01

    Subclinical hypothyroidism (sHT) is considered to be a milder form of thyroid dysfunction. Few earlier studies have reported neuromuscular symptoms as well as impaired muscle metabolism in sHT patients. In this study we report our findings on muscle bioenergetics in sHT patients using phosphorous magnetic resonance spectroscopy (31P MRS) and look upon the possibility to use 31P MRS technique as a clinical marker for monitoring muscle function in subclinical thyroid dysfunction. Seventeen normal subjects, 15 patients with sHT, and 9 patients with hypothyroidism performed plantar flexion exercise while lying supine in 1.5 T magnetic resonance scanner using custom built exercise device. MR Spectroscopy measurements of inorganic phosphate (Pi), phosphocreatine (PCr), and ATP of the calf muscle were taken during rest, at the end of exercise and in the recovery phase. PCr recovery rate constant (kPCr) and oxidative capacity were calculated by monoexponential fit of PCr vs time (t) at the beginning of recovery. We observed that changes in some of the phosphometabolites (increased phosphodiester levels and Pi concentration) in sHT patients which were similar to those detected in patients with hypothyroidism. However, our results do not demonstrate impaired muscle oxidative metabolism in sHT patients based upon PCr dynamics as observed in hypothyroid patients. 31P MRS-based PCr recovery rate could be used as a marker for monitoring muscle oxidative metabolism in sub clinical thyroid dysfunction.

  12. Granulocyte kinetics

    International Nuclear Information System (INIS)

    Peters, A.M.; Lavender, J.P.; Saverymuttu, S.H.

    1985-01-01

    By using density gradient materials enriched with autologous plasma, the authors have been able to isolate granulocutes from other cellular elements and label them with In-111 without separation from a plasma environment. The kinetic behavior of these cells suggests that phenomena attributed to granulocyte activation are greatly reduced by this labeling. Here, they review their study of granulocyte kinetics in health and disease in hope of quantifying sites of margination and identifying principal sites of destruction. The three principle headings of the paper are distribution, life-span, and destruction

  13. Your Muscles

    Science.gov (United States)

    ... and you need to throw up. The muscles push the food back out of the stomach so it comes up ... body the power it needs to lift and push things. Muscles in your neck and the top part of your back aren't as large, but they are capable ...

  14. Exertional oxygen uptake kinetics: a stamen of stamina?

    Science.gov (United States)

    Whipp, Brian J; Rossiter, H B; Ward, S A

    2002-04-01

    The fundamental pulmonary O(2) uptake (.VO(2)) response to moderate, constant-load exercise can be characterized as (d.VO(2)/dt)(tau)+Delta.VO(2) (t)=Delta.VO(2SS) where Delta.VO(2SS) is the steady-state response, and tau is the time constant, with the .VO(2) kinetics reflecting intramuscular O(2) uptake (.QO(2)) kinetics, to within 10%. The role of phosphocreatine (PCr) turnover in .QO(2) control can be explored using (31)P-MR spectroscopy, simultaneously with .VO(2). Although tau.VO(2) and tauPCr vary widely among subjects (approx. 20-65 s), they are not significantly different from each other, either at the on- or off-transient. A caveat to interpreting the "well-fit" exponential is that numerous units of similar Delta.VO(2SS) but with a wide tau distribution can also yield a .VO(2) response with an apparent single tau. This tau is, significantly, inversely correlated with lactate threshold and .VO(2max)(but is poorly predictive; a frail stamen, therefore), consistent with tau not characterizing a compartment with uniform kinetics. At higher intensities, the fundamental kinetics become supplemented with a slowly-developing phase, setting .VO(2)on a trajectory towards maximum .VO(2). This slow component is also demonstrable in Delta[PCr]: the decreased efficiency thereby reflecting a predominantly high phosphate-cost of force production rather than a high O(2)-cost of phosphate production. We also propose that the O(2)-deficit for the slow-component is more likely to reflect shifting Delta.VO(2SS) rather than a single one with a single tau.

  15. Physisorption kinetics

    CERN Document Server

    Kreuzer, Hans Jürgen

    1986-01-01

    This monograph deals with the kinetics of adsorption and desorption of molecules physisorbed on solid surfaces. Although frequent and detailed reference is made to experiment, it is mainly concerned with the theory of the subject. In this, we have attempted to present a unified picture based on the master equation approach. Physisorption kinetics is by no means a closed and mature subject; rather, in writing this monograph we intended to survey a field very much in flux, to assess its achievements so far, and to give a reasonable basis from which further developments can take off. For this reason we have included many papers in the bibliography that are not referred to in the text but are of relevance to physisorption. To keep this monograph to a reasonable size, and also to allow for some unity in the presentation of the material, we had to omit a number of topics related to physisorption kinetics. We have not covered to any extent the equilibrium properties of physisorbed layers such as structures, phase tr...

  16. Muscle cramps

    Science.gov (United States)

    ... the lower leg/calf Back of the thigh (hamstrings) Front of the thigh (quadriceps) Cramps in the ... Names Cramps - muscle Images Chest stretch Groin stretch Hamstring stretch Hip stretch Thigh stretch Triceps stretch References ...

  17. Muscle atrophy

    Science.gov (United States)

    ... People who cannot actively move one or more joints can do exercises using braces or splints . When ... A.M. Editorial team. Muscle Disorders Read more Neuromuscular Disorders Read more NIH MedlinePlus Magazine Read more ...

  18. Stochastic kinetics

    International Nuclear Information System (INIS)

    Colombino, A.; Mosiello, R.; Norelli, F.; Jorio, V.M.; Pacilio, N.

    1975-01-01

    A nuclear system kinetics is formulated according to a stochastic approach. The detailed probability balance equations are written for the probability of finding the mixed population of neutrons and detected neutrons, i.e. detectrons, at a given level for a given instant of time. Equations are integrated in search of a probability profile: a series of cases is analyzed through a progressive criterium. It tends to take into account an increasing number of physical processes within the chosen model. The most important contribution is that solutions interpret analytically experimental conditions of equilibrium (moise analysis) and non equilibrium (pulsed neutron measurements, source drop technique, start up procedures)

  19. Tolrestat kinetics

    International Nuclear Information System (INIS)

    Hicks, D.R.; Kraml, M.; Cayen, M.N.; Dubuc, J.; Ryder, S.; Dvornik, D.

    1984-01-01

    The kinetics of tolrestat, a potent inhibitor of aldose reductase, were examined. Serum concentrations of tolrestat and of total 14 C were measured after dosing normal subjects and subjects with diabetes with 14 C-labeled tolrestat. In normal subjects, tolrestat was rapidly absorbed and disappearance from serum was biphasic. Distribution and elimination t 1/2s were approximately 2 and 10 to 12 hr, respectively, after single and multiple doses. Unchanged tolrestat accounted for the major portion of 14 C in serum. Radioactivity was rapidly and completely excreted in urine and feces in an approximate ratio of 2:1. Findings were much the same in subjects with diabetes. In normal subjects, the kinetics of oral tolrestat were independent of dose in the 10 to 800 mg range. Repetitive dosing did not result in unexpected cumulation. Tolrestat was more than 99% bound to serum protein; it did not compete with warfarin for binding sites but was displaced to some extent by high concentrations of tolbutamide or salicylate

  20. Leucine-Enriched Essential Amino Acids Augment Muscle Glycogen Content in Rats Seven Days after Eccentric Contraction

    Directory of Open Access Journals (Sweden)

    Hiroyuki Kato

    2017-10-01

    Full Text Available Eccentric contractions induce muscle damage, which impairs recovery of glycogen and adenosine tri-phosphate (ATP content over several days. Leucine-enriched essential amino acids (LEAAs enhance the recovery in muscles that are damaged after eccentric contractions. However, the role of LEAAs in this process remains unclear. We evaluated the content in glycogen and high energy phosphates molecules (phosphocreatine (PCr, adenosine di-phosphate (ADP and ATP in rats that were following electrically stimulated eccentric contractions. Muscle glycogen content decreased immediately after the contraction and remained low for the first three days after the stimulation, but increased seven days after the eccentric contraction. LEAAs administration did not change muscle glycogen content during the first three days after the contraction. Interestingly, however, it induced a further increase in muscle glycogen seven days after the stimulation. Contrarily, ATP content decreased immediately after the eccentric contraction, and remained lower for up to seven days after. Additionally, LEAAs administration did not affect the ATP content over the experimental period. Finally, ADP and PCr levels did not significantly change after the contractions or LEAA administration. LEAAs modulate the recovery of glycogen content in muscle after damage-inducing exercise.

  1. Novel Tyrosine Phosphorylation Sites in Rat Skeletal Muscle Revealed by Phosphopeptide Enrichment and HPLC-ESI-MS/MS

    Science.gov (United States)

    Zhang, Xiangmin; Højlund, Kurt; Luo, Moulun; Meyer, Christian; Thangiah, Geetha; Yi, Zhengping

    2012-01-01

    Tyrosine phosphorylation plays a fundamental role in many cellular processes including differentiation, growth and insulin signaling. In insulin resistant muscle, aberrant tyrosine phosphorylation of several proteins has been detected. However, due to the low abundance of tyrosine phosphorylation (tyrosine phosphorylation sites have been identified in mammalian skeletal muscle to date. Here, we used immunoprecipitation of phosphotyrosine peptides prior to HPLC-ESI-MS/MS analysis to improve the discovery of tyrosine phosphorylation in relatively small skeletal muscle biopsies from rats. This resulted in the identification of 87 distinctly localized tyrosine phosphorylation sites in 46 muscle proteins. Among them, 31 appear to be novel. The tyrosine phosphorylated proteins included major enzymes in the glycolytic pathway and glycogen metabolism, sarcomeric proteins, and proteins involved in Ca2+ homeostasis and phosphocreatine resynthesis. Among proteins regulated by insulin, we found tyrosine phosphorylation sites in glycogen synthase, and two of its inhibitors, GSK-3α and DYRK1A. Moreover, tyrosine phosphorylation sites were identified in several MAP kinases and a protein tyrosine phosphatase, SHPTP2. These results provide the largest catalogue of mammalian skeletal muscle tyrosine phosphorylation sites to date and provide novel targets for the investigation of human skeletal muscle phosphoproteins in various disease states. PMID:22609512

  2. Creatine Monohydrate Enhances Energy Status and Reduces Glycolysis via Inhibition of AMPK Pathway in Pectoralis Major Muscle of Transport-Stressed Broilers.

    Science.gov (United States)

    Zhang, Lin; Wang, Xiaofei; Li, Jiaolong; Zhu, Xudong; Gao, Feng; Zhou, Guanghong

    2017-08-16

    Creatine monohydrate (CMH) contributes to reduce transport-induced muscle rapid glycolysis and improve meat quality of broilers, but the underlying mechanism is still unknown. Therefore, this study aimed to investigate the molecular mechanisms underlying the ameliorative effects of CMH on muscle glycolysis metabolism of transported broilers during summer. The results showed that 3 h transport during summer elevated chicken live weight loss and plasma corticosterone concentration; decreased muscle concentrations of ATP, creatine, and energy charge value; increased muscle AMP concentration and AMP/ATP ratio; and upregulated muscle mRNA expression of LKB1 and AMPKα2, as well as protein expression of p-LKB1 Thr189 and p-AMPKα Thr172 , which subsequently resulted in rapid glycolysis in the pectoralis major muscle and consequent reduction of meat quality. Dietary addition of CMH at 1200 mg/kg ameliorated transport-induced rapid muscle glycolysis and reduction of meat quality via enhancement of the energy-buffering capacity of intramuscular phosphocreatine/creatine system and inhibition of AMPK pathway.

  3. Charge movement and depolarization-contraction coupling in arthropod vs. vertebrate skeletal muscle.

    OpenAIRE

    Scheuer, T; Gilly, W F

    1986-01-01

    Voltage-dependent charge movement has been characterized in arthropod skeletal muscle. Charge movement in scorpion (Centuroides sculpturatus) muscle is distinguishable from that in vertebrate skeletal muscle by criteria of kinetics, voltage dependence, and pharmacology. The function of scorpion charge movement is gating of calcium channels in the sarcolemma, and depolarization-contraction coupling relies on calcium influx through these channels.

  4. Muscle and Limb Mechanics.

    Science.gov (United States)

    Tsianos, George A; Loeb, Gerald E

    2017-03-16

    Understanding of the musculoskeletal system has evolved from the collection of individual phenomena in highly selected experimental preparations under highly controlled and often unphysiological conditions. At the systems level, it is now possible to construct complete and reasonably accurate models of the kinetics and energetics of realistic muscles and to combine them to understand the dynamics of complete musculoskeletal systems performing natural behaviors. At the reductionist level, it is possible to relate most of the individual phenomena to the anatomical structures and biochemical processes that account for them. Two large challenges remain. At a systems level, neuroscience must now account for how the nervous system learns to exploit the many complex features that evolution has incorporated into muscle and limb mechanics. At a reductionist level, medicine must now account for the many forms of pathology and disability that arise from the many diseases and injuries to which this highly evolved system is inevitably prone. © 2017 American Physiological Society. Compr Physiol 7:429-462, 2017. Copyright © 2017 John Wiley & Sons, Inc.

  5. Kinetic magnetic resonance imaging of orbital blowout fracture with restricted ocular movement

    International Nuclear Information System (INIS)

    Totsuka, Nobuyoshi; Koide, Ryouhei; Inatomi, Makoto; Fukado, Yoshinao; Hisamatsu, Katsuji.

    1992-01-01

    We analyzed the mechanism of gaze limitation in blowout fracture in 19 patients by means of kinetic magnetic resonance imaging (MRI). We could identify herniation of fat tissue and rectus muscles with connective tissue septa in 11 eyes. Depressed rectus muscles were surrounded by fat tissue. In no instance was the rectus muscle actually incarcerated. Entrapped connective tissue septa seemed to prevent movement of affected rectus muscle. We occasionally observed incarcerated connective tissue septa to restrict motility of the optic nerve. (author)

  6. Kinetic compartmental analysis of carnitine metabolism in the dog

    International Nuclear Information System (INIS)

    Rebouche, C.J.; Engel, A.G.

    1983-01-01

    This study was undertaken to quantitate the dynamic parameters of carnitine metabolism in the dog. Six mongrel dogs were given intravenous injections of L-[methyl-3H]carnitine and the specific radioactivity of carnitine was followed in plasma and urine for 19-28 days. The data were analyzed by kinetic compartmental analysis. A three-compartment, open-system model [(a) extracellular fluid, (b) cardiac and skeletal muscle, (c) other tissues, particularly liver and kidney] was adopted and kinetic parameters (carnitine flux, pool sizes, kinetic constants) were derived. In four of six dogs the size of the muscle carnitine pool obtained by kinetic compartmental analysis agreed (+/- 5%) with estimates based on measurement of carnitine concentrations in different muscles. In three of six dogs carnitine excretion rates derived from kinetic compartmental analysis agreed (+/- 9%) with experimentally measured values, but in three dogs the rates by kinetic compartmental analysis were significantly higher than the corresponding rates measured directly. Appropriate chromatographic analyses revealed no radioactive metabolites in muscle or urine of any of the dogs. Turnover times for carnitine were (mean +/- SEM): 0.44 +/- 0.05 h for extracellular fluid, 232 +/- 22 h for muscle, and 7.9 +/- 1.1 h for other tissues. The estimated flux of carnitine in muscle was 210 pmol/min/g of tissue. Whole-body turnover time for carnitine was 62.9 +/- 5.6 days (mean +/- SEM). Estimated carnitine biosynthesis ranged from 2.9 to 28 mumol/kg body wt/day. Results of this study indicate that kinetic compartmental analysis may be applicable to study of human carnitine metabolism

  7. Lower limb asymmetry in mechanical muscle function

    DEFF Research Database (Denmark)

    Jordan, M J; Aagaard, Per; Herzog, W

    2015-01-01

    .05), and the final phase of the SJ (P AI in the CMJ concentric phase (r = 0.57, P Future research is required to assess the role of the CMJ and SJ phase-specific kinetic impulse AI......-R). Elite alpine skiers with ACL-R (n = 9; 26.2 ± 11.8 months post-op) and uninjured skiers (n = 9) participated in neuromuscular screening. Vertical ground reaction force during the CMJ and SJ was assessed using dual force plate methodology to obtain phase-specific bilateral asymmetry indices (AIs......) for kinetic impulse (CMJ and SJ phase-specific kinetic impulse AI). Dual x-ray absorptiometry scanning was used to assess asymmetry in lower body muscle mass. Compared with controls, ACL-R skiers had increased AI in muscle mass (P AI in the CMJ concentric phase (P 

  8. 31P-nuclear magnetic resonance analysis of extracts of vascular smooth muscle

    International Nuclear Information System (INIS)

    Barron, J.T.; Messer, J.V.; Glonek, Thomas

    1986-01-01

    31 P-nuclear magnetic resonance spectroscopy was used to assess phosphate metabolites in perchloric acid extracts of rabbit aorta. In addition to the high energy phosphates, several other phosphorus compounds were detected and quantified. Most notable was the presence of a prominent phosphomonoester compound appearing at a chemical shift of 3.86 delta. This compound constituted 26% of the total extractable tissue phosphorus and is tentatively identified as ribose-5-phosphate, a pentose phosphate pathway intermediate. While ATP and phosphocreatine did not change during glucose and oxygen deprivation or during prolonged muscle contraction, the 3.86delta phosphate decreased significantly. Furthermore, theophylline, an agent that increases intracellular cAMP, also decreased the level of the 3.86 delta phosphate. These results are consistent with the concept that intermediate metabolism sustains high energy phosphate pools in vascular smooth muscle in the steady state under various conditions. The pentose phosphate pathway may play an important role in vascular smooth muscle metabolism. (author)

  9. The reproducibility of 31-phosphorus MRS measures of muscle energetics at 3 Tesla in trained men.

    Directory of Open Access Journals (Sweden)

    Lindsay M Edwards

    Full Text Available OBJECTIVE: Magnetic resonance spectroscopy (MRS provides an exceptional opportunity for the study of in vivo metabolism. MRS is widely used to measure phosphorus metabolites in trained muscle, although there are no published data regarding its reproducibility in this specialized cohort. Thus, the aim of this study was to assess the reproducibility of (31P-MRS in trained skeletal muscle. METHODS: We recruited fifteen trained men (VO(2peak = 4.7±0.8 L min(-1/58±8 mL kg(-1 min(-1 and performed duplicate MR experiments during plantar flexion exercise, three weeks apart. RESULTS: Measures of resting phosphorus metabolites were reproducible, with 1.7 mM the smallest detectable difference in phosphocreatine (PCr. Measures of metabolites during exercise were less reliable: exercising PCr had a coefficient of variation (CV of 27% during exercise, compared with 8% at rest. Estimates of mitochondrial function were variable, but experimentally useful. The CV of PCr(1/2t was 40%, yet much of this variance was inter-subject such that differences of <20% were detectable with n = 15, given a significance threshold of p<0.05. CONCLUSIONS: 31-phosphorus MRS provides reproducible and experimentally useful measures of phosphorus metabolites and mitochondrial function in trained human skeletal muscle.

  10. Effects of dietary energy sources on early postmortem muscle metabolism of finishing pigs.

    Science.gov (United States)

    Li, Yanjiao; Yu, Changning; Li, Jiaolong; Zhang, Lin; Gao, Feng; Zhou, Guanghong

    2017-12-01

    This study investigated the effects of different dietary energy sources on early postmortem muscle metabolism of finishing pigs. Seventy-two barrow (Duroc×Landrace×Yorkshire, DLY) pigs (65.0±2.0 kg) were allotted to three iso-energetic and iso-nitrogenous diets: A (44.1% starch, 5.9% crude fat, and 12.6% neutral detergent fibre [NDF]), B (37.6% starch, 9.5% crude fat, and 15.4% NDF) or C (30.9% starch, 14.3% crude fat, and 17.8% NDF). After the duration of 28-day feeding experiment, 24 pigs (eight per treatment) were slaughtered and the M. longissimus lumborum (LL) samples at 45 min postmortem were collected. Compared with diet A, diet C resulted in greater adenosine triphosphate and decreased phosphocreatine (PCr) concentrations, greater activity of creatine kinase and reduced percentage bound activities of hexokinase (HK), and pyruvate kinase (PK) in LL muscles (p<0.05). Moreover, diet C decreased the phosphor-AKT level and increased the hydroxy-hypoxia-inducible factor-1α (HIF-1α) level, as well as decreased the bound protein expressions of HK II, PKM2, and lactate dehydrogenase A (p<0.05). Diet C with the lowest level of starch and the highest levels of fat and NDF could enhance the PCr utilization and attenuate glycolysis early postmortem in LL muscle of finishing pigs.

  11. Bio-inspired Hybrid Carbon Nanotube Muscles

    Science.gov (United States)

    Kim, Tae Hyeob; Kwon, Cheong Hoon; Lee, Changsun; An, Jieun; Phuong, Tam Thi Thanh; Park, Sun Hwa; Lima, Márcio D.; Baughman, Ray H.; Kang, Tong Mook; Kim, Seon Jeong

    2016-05-01

    There has been continuous progress in the development for biomedical engineering systems of hybrid muscle generated by combining skeletal muscle and artificial structure. The main factor affecting the actuation performance of hybrid muscle relies on the compatibility between living cells and their muscle scaffolds during cell culture. Here, we developed a hybrid muscle powered by C2C12 skeletal muscle cells based on the functionalized multi-walled carbon nanotubes (MWCNT) sheets coated with poly(3,4-ethylenedioxythiophene) (PEDOT) to achieve biomimetic actuation. This hydrophilic hybrid muscle is physically durable in solution and responds to electric field stimulation with flexible movement. Furthermore, the biomimetic actuation when controlled by electric field stimulation results in movement similar to that of the hornworm by patterned cell culture method. The contraction and relaxation behavior of the PEDOT/MWCNT-based hybrid muscle is similar to that of the single myotube movement, but has faster relaxation kinetics because of the shape-maintenance properties of the freestanding PEDOT/MWCNT sheets in solution. Our development provides the potential possibility for substantial innovation in the next generation of cell-based biohybrid microsystems.

  12. In vivo 31P-NMR studies on the energy metabolism of atrophic muscles in rate

    International Nuclear Information System (INIS)

    Yamagiwa, Tetsuo

    1988-01-01

    Using P-31 NMR spectra, energy metabolism in the rat calf muscle was examined. The body weight in the atrophy and control groups did not differ significantly. Both the wet weight and dry weight of the calf muscle were significantly lower in the atrophy group than the control group. The muscle weight relative to the body weight was significantly lower in the atrophy group as well than the control group. There was no significant difference in the P-31 NMR spectral pattern before tourniquet ischemia between the atrophy and control groups. Rapid decrease in phosphocreatine (PCr) and rapid increase in inorganic phosphate (Pi) were observed in both groups immediately after application of the tourniquet; however, the rates of these changes were slightly greater and the PCr/Pi ratio in the peak values was significantly smaller in the atrophy group than the control group. The pH value before the ischemia was 7.15 ± 0.02 for the control group and 7.16 ± 0.02 for the atrophy group, with no significant difference between the groups. During ischemia, the pH value decreased progressively in the two groups; however, it became significantly decreased in the atrophy group from 10 to 60 min after application of tourniquet. The decrease in pH became gradual 60 min later. Since the decrease in pH was more rapid in the atrophic muscle than the intact muscle, this buffering capacity seems to be reduced in the atrophic muscle. (N.K.)

  13. The effect of neoadjuvant chemoradiotherapy on whole-body physical fitness and skeletal muscle mitochondrial oxidative phosphorylation in vivo in locally advanced rectal cancer patients--an observational pilot study.

    Directory of Open Access Journals (Sweden)

    Malcolm A West

    Full Text Available In the United Kingdom, patients with locally advanced rectal cancer routinely receive neoadjuvant chemoradiotherapy. However, the effects of this on physical fitness are unclear. This pilot study is aimed to investigate the effect of neoadjuvant chemoradiotherapy on objectively measured in vivo muscle mitochondrial function and whole-body physical fitness.We prospectively studied 12 patients with rectal cancer who completed standardized neoadjuvant chemoradiotherapy, recruited from a large tertiary cancer centre, between October 2012 and July 2013. All patients underwent a cardiopulmonary exercise test and a phosphorus magnetic resonance spectroscopy quadriceps muscle exercise-recovery study before and after neoadjuvant chemoradiotherapy. Data were analysed and reported blind to patient identity and clinical course. Primary variables of interest were the two physical fitness measures; oxygen uptake at estimated anaerobic threshold and oxygen uptake at Peak exercise (ml.kg-1.min-1, and the post-exercise phosphocreatine recovery rate constant (min-1, a measure of muscle mitochondrial capacity in vivo.Median age was 67 years (IQR 64-75. Differences (95%CI in all three primary variables were significantly negative post-NACRT: Oxygen uptake at estimated anaerobic threshold -2.4 ml.kg-1.min-1 (-3.8, -0.9, p = 0.004; Oxygen uptake at Peak -4.0 ml.kg-1.min-1 (-6.8, -1.1, p = 0.011; and post-exercise phosphocreatine recovery rate constant -0.34 min-1 (-0.51, -0.17, p<0.001.The significant decrease in both whole-body physical fitness and in vivo muscle mitochondrial function raises the possibility that muscle mitochondrial mechanisms, no doubt multifactorial, may be important in deterioration of physical fitness following neoadjuvant chemoradiotherapy. This may have implications for targeted interventions to improve physical fitness pre-surgery.Clinicaltrials.gov registration NCT01859442.

  14. Reconstruction of Cell Surface Densities of Ion Pumps, Exchangers, and Channels from mRNA Expression, Conductance Kinetics, Whole-Cell Calcium, and Current-Clamp Voltage Recordings, with an Application to Human Uterine Smooth Muscle Cells.

    Directory of Open Access Journals (Sweden)

    Jolene Atia

    2016-04-01

    Full Text Available Uterine smooth muscle cells remain quiescent throughout most of gestation, only generating spontaneous action potentials immediately prior to, and during, labor. This study presents a method that combines transcriptomics with biophysical recordings to characterise the conductance repertoire of these cells, the 'conductance repertoire' being the total complement of ion channels and transporters expressed by an electrically active cell. Transcriptomic analysis provides a set of potential electrogenic entities, of which the conductance repertoire is a subset. Each entity within the conductance repertoire was modeled independently and its gating parameter values were fixed using the available biophysical data. The only remaining free parameters were the surface densities for each entity. We characterise the space of combinations of surface densities (density vectors consistent with experimentally observed membrane potential and calcium waveforms. This yields insights on the functional redundancy of the system as well as its behavioral versatility. Our approach couples high-throughput transcriptomic data with physiological behaviors in health and disease, and provides a formal method to link genotype to phenotype in excitable systems. We accurately predict current densities and chart functional redundancy. For example, we find that to evoke the observed voltage waveform, the BK channel is functionally redundant whereas hERG is essential. Furthermore, our analysis suggests that activation of calcium-activated chloride conductances by intracellular calcium release is the key factor underlying spontaneous depolarisations.

  15. Leg and arm lactate and substrate kinetics during exercise

    DEFF Research Database (Denmark)

    Van Hall, Gerrit; Jensen-Urstad, M; Rosdahl, H

    2003-01-01

    To study the role of muscle mass and muscle activity on lactate and energy kinetics during exercise, whole body and limb lactate, glucose, and fatty acid fluxes were determined in six elite cross-country skiers during roller-skiing for 40 min with the diagonal stride (Continuous Arm + Leg) followed...... kinetics changed multiple times when exercise mode was changed. Whole body glucose and glycerol turnover was unchanged during the different skiing modes; however, limb net glucose uptake changed severalfold. In conclusion, the arterial lactate concentration can be maintained at a relatively low level...... despite high lactate R(a) during exercise with a large muscle mass because of the large capacity of active skeletal muscle to take up lactate, which is tightly correlated with lactate delivery. The limb lactate uptake during exercise is oxidized at rates far above resting oxygen consumption, implying...

  16. Extraocular muscle function testing

    Science.gov (United States)

    ... medlineplus.gov/ency/article/003397.htm Extraocular muscle function testing To use the sharing features on this page, please enable JavaScript. Extraocular muscle function testing examines the function of the eye muscles. ...

  17. Cesium removal and kinetics equilibrium: Precipitation kinetics

    International Nuclear Information System (INIS)

    Barnes, M.J.

    1999-01-01

    This task consisted of both non-radioactive and radioactive (tracer) tests examining the influence of potentially significant variables on cesium tetraphenylborate precipitation kinetics. The work investigated the time required to reach cesium decontamination and the conditions that affect the cesium precipitation kinetics

  18. Kinetic chain abnormalities in the athletic shoulder.

    Science.gov (United States)

    Sciascia, Aaron; Thigpen, Charles; Namdari, Surena; Baldwin, Keith

    2012-03-01

    Overhead activities require the shoulder to be exposed to and sustain repetitive loads. The segmental activation of the body's links, known as the kinetic chain, allows this to occur effectively. Proper muscle activation is achieved through generation of energy from the central segment or core, which then transfers the energy to the terminal links of the shoulder, elbow, and hand. The kinetic chain is best characterized by 3 components: optimized anatomy, reproducible efficient motor patterns, and the sequential generation of forces. However, tissue injury and anatomic deficits such as weakness and/or tightness in the leg, pelvic core, or scapular musculature can lead to overuse shoulder injuries. These injuries can be prevented and maladaptations can be detected with a thorough understanding of biomechanics of the kinetic chain as it relates to overhead activity.

  19. Energy demand and supply in human skeletal muscle.

    Science.gov (United States)

    Barclay, C J

    2017-04-01

    The energy required for muscle contraction is provided by the breakdown of ATP but the amount of ATP in muscles cells is sufficient to power only a short duration of contraction. Buffering of ATP by phosphocreatine, a reaction catalysed by creatine kinase, extends the duration of activity possible but sustained activity depends on continual regeneration of PCr. This is achieved using ATP generated by oxidative processes and, during intense activity, by anaerobic glycolysis. The rate of ATP breakdown ranges from 70 to 140 mM min -1 during isometric contractions of various intensity to as much as 400 mM min -1 during intense, dynamic activity. The maximum rate of oxidative energy supply in untrained people is ~50 mM min -1 which, if the contraction duty cycle is 0.5 as is often the case in cyclic activity, is sufficient to match an ATP breakdown rate during contraction of 100 mM min -1 . During brief, intense activity the rate of ATP turnover can exceed the rates of PCr regeneration by combined oxidative and glycolytic energy supply, resulting in a net decrease in PCr concentration. Glycolysis has the capacity to produce between 30 and 50 mM of ATP so that, for example, anaerobic glycolysis could provide ATP at an average of 100 mM min -1 over 30 s of exhausting activity. The creatine kinase reaction plays an important role not only in buffering ATP but also in communicating energy demand from sites of ATP breakdown to the mitochondria. In that role, creatine kinases acts to slow and attenuate the response of mitochondria to changes in energy demand.

  20. Exercise: Kinetic considerations for gas exchange.

    Science.gov (United States)

    Rossiter, Harry B

    2011-01-01

    The activities of daily living typically occur at metabolic rates below the maximum rate of aerobic energy production. Such activity is characteristic of the nonsteady state, where energy demands, and consequential physiological responses, are in constant flux. The dynamics of the integrated physiological processes during these activities determine the degree to which exercise can be supported through rates of O₂ utilization and CO₂ clearance appropriate for their demands and, as such, provide a physiological framework for the notion of exercise intensity. The rate at which O₂ exchange responds to meet the changing energy demands of exercise--its kinetics--is dependent on the ability of the pulmonary, circulatory, and muscle bioenergetic systems to respond appropriately. Slow response kinetics in pulmonary O₂ uptake predispose toward a greater necessity for substrate-level energy supply, processes that are limited in their capacity, challenge system homeostasis and hence contribute to exercise intolerance. This review provides a physiological systems perspective of pulmonary gas exchange kinetics: from an integrative view on the control of muscle oxygen consumption kinetics to the dissociation of cellular respiration from its pulmonary expression by the circulatory dynamics and the gas capacitance of the lungs, blood, and tissues. The intensity dependence of gas exchange kinetics is discussed in relation to constant, intermittent, and ramped work rate changes. The influence of heterogeneity in the kinetic matching of O₂ delivery to utilization is presented in reference to exercise tolerance in endurance-trained athletes, the elderly, and patients with chronic heart or lung disease. © 2011 American Physiological Society.

  1. Plasma kinetic theory

    International Nuclear Information System (INIS)

    Elliott, J.A.

    1993-01-01

    Plasma kinetic theory is discussed and a comparison made with the kinetic theory of gases. The plasma is described by a modified set of fluid equations and it is shown how these fluid equations can be derived. (UK)

  2. Oxygen delivery and the restoration of the muscle energetic balance following exercise: implications for delayed muscle recovery in patients with COPD.

    Science.gov (United States)

    Layec, Gwenael; Hart, Corey R; Trinity, Joel D; Kwon, Oh-Sung; Rossman, Matthew J; Broxterman, Ryan M; Le Fur, Yann; Jeong, Eun-Kee; Richardson, Russell S

    2017-07-01

    Patients with chronic obstructive pulmonary disease (COPD) experience a delayed recovery from skeletal muscle fatigue following exhaustive exercise that likely contributes to their progressive loss of mobility. As this phenomenon is not well understood, this study sought to examine postexercise peripheral oxygen (O 2 ) transport and muscle metabolism dynamics in patients with COPD, two important determinants of muscle recovery. Twenty-four subjects, 12 nonhypoxemic patients with COPD and 12 healthy subjects with a sedentary lifestyle, performed dynamic plantar flexion exercise at 40% of the maximal work rate (WR max ) with phosphorus magnetic resonance spectroscopy ( 31 P-MRS), near-infrared spectroscopy (NIRS), and vascular Doppler ultrasound assessments. The mean response time of limb blood flow at the offset of exercise was significantly prolonged in patients with COPD (controls: 56 ± 27 s; COPD: 120 ± 87 s; P 0.05). The initial postexercise convective O 2 delivery (controls: 0.15 ± 0.06 l/min; COPD: 0.15 ± 0.06 l/min) and the corresponding oxidative adenosine triphosphate (ATP) demand (controls: 14 ± 6 mM/min; COPD: 14 ± 6 mM/min) in the calf were not significantly different between controls and patients with COPD ( P > 0.05). The phosphocreatine resynthesis time constant (controls: 46 ± 20 s; COPD: 49 ± 21 s), peak mitochondrial phosphorylation rate, and initial proton efflux were also not significantly different between groups ( P > 0.05). Therefore, despite perturbed peripheral hemodynamics, intracellular O 2 availability, proton efflux, and aerobic metabolism recovery in the skeletal muscle of nonhypoxemic patients with COPD are preserved following plantar flexion exercise and thus are unlikely to contribute to the delayed recovery from exercise in this population.

  3. Coordination patterns of shoulder muscles during level-ground and incline wheelchair propulsion.

    Science.gov (United States)

    Qi, Liping; Wakeling, James; Grange, Simon; Ferguson-Pell, Martin

    2013-01-01

    The aim of this study was to investigate how the coordination patterns of shoulder muscles change with level-ground and incline wheelchair propulsion. Wheelchair kinetics and electromyography (EMG) activity of seven muscles were recorded with surface electrodes for 15 nondisabled subjects during wheelchair propulsion on a stationary ergometer and wooden ramp (4 degree slope). Kinetic data were measured by a SmartWheel. The kinetics variables and the onset, cessation, and duration of EMG activity from seven muscles were compared with paired t-tests for two sessions. Muscle coordination patterns across seven muscles were analyzed by principal component analysis. Push forces on the push rim and the percentage of push phase in the cycle increased significantly during incline propulsion. Propulsion condition and posture affected muscle coordination patterns. During incline propulsion, there was more intense and longer EMG activity of push muscles in the push phase and less EMG activity of the recovery muscles, which corresponded with the increased kinetic data total force output and longer push phase in the incline condition. This work establishes a framework for developing a performance feedback system for wheelchair users to better coordinate their muscle patterning activity.

  4. Training-induced adaptation of oxidative phosphorylation in skeletal muscles.

    OpenAIRE

    Korzeniewski, Bernard; Zoladz, Jerzy A

    2003-01-01

    Muscle training/conditioning improves the adaptation of oxidative phosphorylation in skeletal muscles to physical exercise. However, the mechanisms underlying this adaptation are still not understood fully. By quantitative analysis of the existing experimental results, we show that training-induced acceleration of oxygen-uptake kinetics at the onset of exercise and improvement of ATP/ADP stability due to physical training are mainly caused by an increase in the amount of mitochondrial protein...

  5. Neuromuscular blockade of slow twitch muscle fibres elevates muscle oxygen uptake and energy turnover during submaximal exercise in humans.

    Science.gov (United States)

    Krustrup, Peter; Secher, Niels H; Relu, Mihai U; Hellsten, Ylva; Söderlund, Karin; Bangsbo, Jens

    2008-12-15

    We tested the hypothesis that a greater activation of fast-twitch (FT) fibres during dynamic exercise leads to a higher muscle oxygen uptake (VO2 ) and energy turnover as well as a slower muscle on-kinetics. Subjects performed one-legged knee-extensor exercise for 10 min at an intensity of 30 W without (CON) and with (CUR) arterial injections of the non-depolarizing neuromuscular blocking agent cisatracurium. In CUR, creatine phosphate (CP) was unaltered in slow twitch (ST) fibres and decreased (P fibres, whereas in CON, CP decreased (P fibres, respectively. From 127 s of exercise, muscle VO2 was higher (P muscle VO2 response was slower (P muscle homogenate CP was lowered (P muscle lactate production was similar in CUR and CON (37.8 +/- 4.1 versus 35.2 +/- 6.2 mmol). Estimated total muscle ATP turnover was 19% higher (P fibres are less efficient than ST fibres in vivo at a contraction frequency of 1 Hz, and that the muscle VO2 kinetics is slowed by FT fibre activation.

  6. Exertional muscle pain in familial Mediterranean fever patients evaluated by MRI and 31P magnetic resonance spectroscopy

    International Nuclear Information System (INIS)

    Kushnir, T.; Eshed, I.; Heled, Y.; Livneh, A.; Langevitz, P.; Ben Zvi, I.; Konen, E.; Lidar, M.

    2013-01-01

    Aim: To evaluate the effect of physical activity on the structural, morphological, and metabolic characteristics of the gastrocnemius muscle in familial Mediterranean fever (FMF) patients, utilizing quantitative 31 P magnetic resonance spectroscopy (MRS), in order to elucidate the mechanism of their exertional leg pain. Materials and methods: Eleven FMF patients suffering from exertional leg pain (eight male, three female; mean age 33 years) and six healthy individuals (three male, three female; mean age 39 years) constituted the control group. All of the participants underwent magnetic resonance imaging (MRI) and non-selective 31 P MRS (3 T) of the leg muscles before and after graded exercise on a treadmill. Phosphocreatine (PCr):inorganic phosphate (Pi), PCr:adenosine triphosphate (ATP) ratios and the intracellular pH of the leg muscles were measured using 31 P MRS. Results: For both groups, normal muscle mass with no signal alterations was observed on the MRI images after exercise. The normal range of pre- and post- exercise MRS muscle parameters was observed in both groups. However, the intracellular pH post-exercise, was significantly higher (less acidic) in the FMF group compared to the control group [pH (FMF) = 7.03 ± 0.02; pH (control) 7.00 ± 0.02; p < 0.0006]. Conclusions: The finding of a less prominent, post-exercise acidification of the gastrocnemius muscle in this FMF patient group suggests a forme fruste of glycogenosis. This preliminary observation should be further investigated in a future, larger-scale study

  7. Bion 11 Spaceflight Project: Effect of Weightlessness on Single Muscle Fiber Function in Rhesus Monkeys

    Science.gov (United States)

    Fitts, Robert H.; Romatowski, Janell G.; Widrick, Jeffrey J.; DeLaCruz, Lourdes

    1999-01-01

    Although it is well known that microgravity induces considerable limb muscle atrophy, little is known about how weightlessness alters cell function. In this study, we investigated how weightlessness altered the functional properties of single fast and slow striated muscle fibers. Physiological studies were carried out to test the hypothesis that microgravity causes fiber atrophy, a decreased peak force (Newtons), tension (Newtons/cross-sectional area) and power, an elevated peak rate of tension development (dp/dt), and an increased maximal shortening velocity (V(sub o)) in the slow type I fiber, while changes in the fast-twitch fiber are restricted to atrophy and a reduced peak force. For each fiber, we determined the peak force (P(sub o)), V(sub o), dp/dt, the force-velocity relationship, peak power, the power-force relationship, the force-pCa relationship, and fiber stiffness. Biochemical studies were carried out to assess the effects of weightlessness on the enzyme and substrate profile of the fast- and slow-twitch fibers. We predicted that microgravity would increase resting muscle glycogen and glycolytic metabolism in the slow fiber type, while the fast-twitch fiber enzyme profile would be unaltered. The increased muscle glycogen would in part result from an elevated hexokinase and glycogen synthase. The enzymes selected for study represent markers for mitochondrial function (citrate synthase and 0-hydroxyacyl-CoA dehydrogenase), glycolysis (Phosphofructokinase and lactate dehydrogenase), and fatty acid transport (Carnitine acetyl transferase). The substrates analyzed will include glycogen, lactate, adenosine triphosphate, and phosphocreatine.

  8. Lower leg muscle involvement in Duchenne muscular dystrophy: an MR imaging and spectroscopy study

    International Nuclear Information System (INIS)

    Torriani, Martin; Townsend, Elise; Thomas, Bijoy J.; Bredella, Miriam A.; Ghomi, Reza H.; Tseng, Brian S.

    2012-01-01

    To describe the involvement of lower leg muscles in boys with Duchenne muscular dystrophy (DMD) by using MR imaging (MRI) and spectroscopy (MRS) correlated to indices of functional status. Nine boys with DMD (mean age, 11 years) and eight healthy age- and BMI-matched boys (mean age, 13 years) prospectively underwent lower leg MRI, 1H-MRS of tibialis anterior (TA) and soleus (SOL) for lipid fraction measures, and 31P-MRS for pH and high-energy phosphate measures. DMD subjects were evaluated using the Vignos lower extremity functional rating, and tests including 6 min walk test (6MWT) and 10 m walk. DMD subjects had highest fatty infiltration scores in peroneal muscles, followed by medial gastrocnemius and soleus. Compared to controls, DMD boys showed higher intramuscular fat (P = 0.04), lipid fractions of TA and SOL (P = 0.02 and 0.003, respectively), pH of anterior compartment (P = 0.0003), and lower phosphocreatine/inorganic phosphorus ratio of posterior compartment (P = 0.02). The Vignos rating correlated with TA (r = 0.79, P = 0.01) and SOL (r = 0.71, P = 0.03) lipid fractions. The 6MWT correlated with fatty infiltration scores of SOL (r = -0.76, P = 0.046), medial (r = -0.80, P = 0.03) and lateral (r = -0.84, P = 0.02) gastrocnemius, intramuscular fat (r = -0.80, P = 0.03), and SOL lipid fraction (r = -0.89, P = 0.007). Time to walk 10 m correlated with anterior compartment pH (r = 0.78, P = 0.04). Lower leg muscles of boys with DMD show a distinct involvement pattern and increased adiposity that correlates with functional status. Lower leg MRI and 1H-MRS studies may help to noninvasively demonstrate the severity of muscle involvement. (orig.)

  9. Lower leg muscle involvement in Duchenne muscular dystrophy: an MR imaging and spectroscopy study

    Energy Technology Data Exchange (ETDEWEB)

    Torriani, Martin [Massachusetts General Hospital and Harvard Medical School, Division of Musculoskeletal Imaging and Intervention, Boston, MA (United States); Massachusetts General Hospital, Musculoskeletal Imaging and Intervention, Department of Radiology, Boston, MA (United States); Townsend, Elise [MGH Institute of Health Professions and Massachusetts General Hospital, Boston, MA (United States); Thomas, Bijoy J.; Bredella, Miriam A.; Ghomi, Reza H. [Massachusetts General Hospital and Harvard Medical School, Division of Musculoskeletal Imaging and Intervention, Boston, MA (United States); Tseng, Brian S. [Massachusetts General Hospital and Harvard Medical School, Pediatric Neuromuscular Clinic, Boston, MA (United States); Novartis Institute of Biomedical Research, Cambridge, MA (United States)

    2012-04-15

    To describe the involvement of lower leg muscles in boys with Duchenne muscular dystrophy (DMD) by using MR imaging (MRI) and spectroscopy (MRS) correlated to indices of functional status. Nine boys with DMD (mean age, 11 years) and eight healthy age- and BMI-matched boys (mean age, 13 years) prospectively underwent lower leg MRI, 1H-MRS of tibialis anterior (TA) and soleus (SOL) for lipid fraction measures, and 31P-MRS for pH and high-energy phosphate measures. DMD subjects were evaluated using the Vignos lower extremity functional rating, and tests including 6 min walk test (6MWT) and 10 m walk. DMD subjects had highest fatty infiltration scores in peroneal muscles, followed by medial gastrocnemius and soleus. Compared to controls, DMD boys showed higher intramuscular fat (P = 0.04), lipid fractions of TA and SOL (P = 0.02 and 0.003, respectively), pH of anterior compartment (P = 0.0003), and lower phosphocreatine/inorganic phosphorus ratio of posterior compartment (P = 0.02). The Vignos rating correlated with TA (r = 0.79, P = 0.01) and SOL (r = 0.71, P = 0.03) lipid fractions. The 6MWT correlated with fatty infiltration scores of SOL (r = -0.76, P = 0.046), medial (r = -0.80, P = 0.03) and lateral (r = -0.84, P = 0.02) gastrocnemius, intramuscular fat (r = -0.80, P = 0.03), and SOL lipid fraction (r = -0.89, P = 0.007). Time to walk 10 m correlated with anterior compartment pH (r = 0.78, P = 0.04). Lower leg muscles of boys with DMD show a distinct involvement pattern and increased adiposity that correlates with functional status. Lower leg MRI and 1H-MRS studies may help to noninvasively demonstrate the severity of muscle involvement. (orig.)

  10. Heterogeneity in limb fatty acid kinetics in type 2 diabetes

    DEFF Research Database (Denmark)

    Sacchetti, M; Olsen, D B; Saltin, B

    2005-01-01

    AIMS/HYPOTHESIS: In order to test the hypothesis that disturbances in skeletal muscle fatty acid metabolism with type 2 diabetes are not equally present in the upper and lower limbs, we studied fatty acid kinetics simultaneously across the arm and leg of type 2 diabetic patients (n=6) and matched...... control subjects (n=7) for 5 h under baseline conditions and during a 4-h hyperinsulinaemic-euglycaemic clamp. METHODS: Limb fatty acid kinetics was determined by means of continuous [U-(13)C]palmitate infusion and measurement of arteriovenous differences. RESULTS: The systemic palmitate rate...... in the dysregulation of skeletal muscle fatty acid metabolism, with only the leg, but not the arm, showing an impairment of fatty acid kinetics at baseline and during a hyperinsulinaemic-euglycaemic clamp causing a physiological increase in insulin concentration....

  11. Caffeine and contraction synergistically stimulate 5′-AMP-activated protein kinase and insulin-independent glucose transport in rat skeletal muscle

    Science.gov (United States)

    Tsuda, Satoshi; Egawa, Tatsuro; Kitani, Kazuto; Oshima, Rieko; Ma, Xiao; Hayashi, Tatsuya

    2015-01-01

    5′-Adenosine monophosphate-activated protein kinase (AMPK) has been identified as a key mediator of contraction-stimulated insulin-independent glucose transport in skeletal muscle. Caffeine acutely stimulates AMPK in resting skeletal muscle, but it is unknown whether caffeine affects AMPK in contracting muscle. Isolated rat epitrochlearis muscle was preincubated and then incubated in the absence or presence of 3 mmol/L caffeine for 30 or 120 min. Electrical stimulation (ES) was used to evoke tetanic contractions during the last 10 min of the incubation period. The combination of caffeine plus contraction had additive effects on AMPKα Thr172 phosphorylation, α-isoform-specific AMPK activity, and 3-O-methylglucose (3MG) transport. In contrast, caffeine inhibited basal and contraction-stimulated Akt Ser473 phosphorylation. Caffeine significantly delayed muscle fatigue during contraction, and the combination of caffeine and contraction additively decreased ATP and phosphocreatine contents. Caffeine did not affect resting tension. Next, rats were given an intraperitoneal injection of caffeine (60 mg/kg body weight) or saline, and the extensor digitorum longus muscle was dissected 15 min later. ES of the sciatic nerve was performed to evoke tetanic contractions for 5 min before dissection. Similar to the findings from isolated muscles incubated in vitro, the combination of caffeine plus contraction in vivo had additive effects on AMPK phosphorylation, AMPK activity, and 3MG transport. Caffeine also inhibited basal and contraction-stimulated Akt phosphorylation in vivo. These findings suggest that caffeine and contraction synergistically stimulate AMPK activity and insulin-independent glucose transport, at least in part by decreasing muscle fatigue and thereby promoting energy consumption during contraction. PMID:26471759

  12. Caffeine and contraction synergistically stimulate 5'-AMP-activated protein kinase and insulin-independent glucose transport in rat skeletal muscle.

    Science.gov (United States)

    Tsuda, Satoshi; Egawa, Tatsuro; Kitani, Kazuto; Oshima, Rieko; Ma, Xiao; Hayashi, Tatsuya

    2015-10-01

    5'-Adenosine monophosphate-activated protein kinase (AMPK) has been identified as a key mediator of contraction-stimulated insulin-independent glucose transport in skeletal muscle. Caffeine acutely stimulates AMPK in resting skeletal muscle, but it is unknown whether caffeine affects AMPK in contracting muscle. Isolated rat epitrochlearis muscle was preincubated and then incubated in the absence or presence of 3 mmol/L caffeine for 30 or 120 min. Electrical stimulation (ES) was used to evoke tetanic contractions during the last 10 min of the incubation period. The combination of caffeine plus contraction had additive effects on AMPKα Thr(172) phosphorylation, α-isoform-specific AMPK activity, and 3-O-methylglucose (3MG) transport. In contrast, caffeine inhibited basal and contraction-stimulated Akt Ser(473) phosphorylation. Caffeine significantly delayed muscle fatigue during contraction, and the combination of caffeine and contraction additively decreased ATP and phosphocreatine contents. Caffeine did not affect resting tension. Next, rats were given an intraperitoneal injection of caffeine (60 mg/kg body weight) or saline, and the extensor digitorum longus muscle was dissected 15 min later. ES of the sciatic nerve was performed to evoke tetanic contractions for 5 min before dissection. Similar to the findings from isolated muscles incubated in vitro, the combination of caffeine plus contraction in vivo had additive effects on AMPK phosphorylation, AMPK activity, and 3MG transport. Caffeine also inhibited basal and contraction-stimulated Akt phosphorylation in vivo. These findings suggest that caffeine and contraction synergistically stimulate AMPK activity and insulin-independent glucose transport, at least in part by decreasing muscle fatigue and thereby promoting energy consumption during contraction. © 2015 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of the American Physiological Society and The Physiological

  13. Principles of chemical kinetics

    CERN Document Server

    House, James E

    2007-01-01

    James House's revised Principles of Chemical Kinetics provides a clear and logical description of chemical kinetics in a manner unlike any other book of its kind. Clearly written with detailed derivations, the text allows students to move rapidly from theoretical concepts of rates of reaction to concrete applications. Unlike other texts, House presents a balanced treatment of kinetic reactions in gas, solution, and solid states. The entire text has been revised and includes many new sections and an additional chapter on applications of kinetics. The topics covered include quantitative rela

  14. Introduction to chemical kinetics

    CERN Document Server

    Soustelle, Michel

    2013-01-01

    This book is a progressive presentation of kinetics of the chemical reactions. It provides complete coverage of the domain of chemical kinetics, which is necessary for the various future users in the fields of Chemistry, Physical Chemistry, Materials Science, Chemical Engineering, Macromolecular Chemistry and Combustion. It will help them to understand the most sophisticated knowledge of their future job area. Over 15 chapters, this book present the fundamentals of chemical kinetics, its relations with reaction mechanisms and kinetic properties. Two chapters are then devoted to experimental re

  15. Kinetic equation solution by inverse kinetic method

    International Nuclear Information System (INIS)

    Salas, G.

    1983-01-01

    We propose a computer program (CAMU) which permits to solve the inverse kinetic equation. The CAMU code is written in HPL language for a HP 982 A microcomputer with a peripheral interface HP 9876 A ''thermal graphic printer''. The CAMU code solves the inverse kinetic equation by taking as data entry the output of the ionization chambers and integrating the equation with the help of the Simpson method. With this program we calculate the evolution of the reactivity in time for a given disturbance

  16. The effect of exercise types for rotator cuff repair patients on activities of shoulder muscles and upper limb disability.

    Science.gov (United States)

    Kang, Jeong-Il; Moon, Young-Jun; Choi, Hyun; Jeong, Dae-Keun; Kwon, Hye-Min; Park, Jun-Su

    2016-10-01

    [Purpose] This study investigated the effect on activities, shoulder muscle fatigue, upper limb disability of two exercise types performed by patients in the post- immobilization period of rotator cuff repair. [Subjects and Methods] The intervention program was performed by 20 patients from 6 weeks after rotator cuff repair. Ten subjects each were randomly allocated to a group performing open kinetic chain exercise and a group preforming closed kinetic chain exercise. Muscle activity and median frequency were measured by using sEMG and the Upper Extremity Function Assessment before and after conducting the intervention and changes in the results were compared. [Results] There was a significant within group increases in the activities of the shoulder muscles, except for the posterior deltoid. The median power frequencies (MFD) of the supraspinatus, infraspinatus and anterior deltoid significantly increased in the open kinetic chain exercise group, but that of the posterior deltoid decreased. There were significant differences in the changes in the upper limb disability scores of the two groups, in the shoulder muscle activities, except for that of the posterior deltoid, in the comparison of the change in the muscle activities of the two groups, and in the MDFs of all shoulder muscles. [Conclusion] The Median power frequencies of all these muscles after closed kinetic chain exercise increased indicating that muscle fatigue decreased. Therefore, research into exercise programs using closed kinetic chain exercises will be needed to establish exercise methods for reducing muscle fatigue.

  17. Functional Echomyography of the human denervated muscle: first results

    Directory of Open Access Journals (Sweden)

    Riccardo Zanato

    2011-03-01

    Full Text Available In this study we followed with ultrasound three patients with permanent denervation to evaluate changes in morphology, thickness, contraction and vascularisation of muscles undergoing the home-based electrical stimulation program of the Rise2-Italy project. During a period of 1 year for the first subject, 6 months for the second subject and 3 months for the third subject we studied with ultrasound the denervated muscle comparing it (if possible to the contralateral normal muscle. We evaluated: 1. Changes in morphology and sonographic structure of the pathologic muscle; 2. Muscular thickness in response to the electrical stimulation therapy; 3. Short-term modifications in muscle perfusion and arterial flow patterns after stimulation; 4. Contraction-relaxation kinetic induced by volitional activity or electrical stimulation. Morphology and ultrasonographic structure of the denervated muscles changed during the period of stimulation from a pattern typical of complete muscular atrophy to a pattern which might be considered “normal” when detected in an old patient. Thickness improved significantly more in the middle third than in the proximal and distal third of the denervated muscle, reaching in the last measurements of the first subject approximately the same thickness as the contralateral normal muscle. In all the measurements done within this study, arterial flow of the denervated muscle showed at rest a low-resistance pattern with Doppler Ultra Sound (US, and a pulsed pattern after electrical stimulation. The stimulation- induced pattern is similar to the trifasic high-resistance pattern of the normal muscle. Contraction- relaxation kinetic, measured by recording the muscular movements during electrical stimulation, showed an abnormal behaviour of the denervated muscle during the relaxation phase, which resulted to be significantly longer than in normal muscle (880 msec in the denervated muscle vs 240 msec in the contralateral normal one

  18. A Trap Motion in Validating Muscle Activity Prediction from Musculoskeletal Model using EMG

    NARCIS (Netherlands)

    Wibawa, A. D.; Verdonschot, N.; Halbertsma, J.P.K.; Burgerhof, J.G.M.; Diercks, R.L.; Verkerke, G. J.

    2016-01-01

    Musculoskeletal modeling nowadays is becoming the most common tool for studying and analyzing human motion. Besides its potential in predicting muscle activity and muscle force during active motion, musculoskeletal modeling can also calculate many important kinetic data that are difficult to measure

  19. Quantification of skeletal muscle mitochondrial function by 31P magnetic resonance spectroscopy techniques : A quantitative review

    NARCIS (Netherlands)

    Kemp, G.J.; Ahmad, R.E.; Nicolay, K.; Prompers, J.J.

    2015-01-01

    Magnetic resonance spectroscopy (MRS) can give information about cellular metabolism in vivo which is difficult to obtain in other ways. In skeletal muscle, non-invasive 31P MRS measurements of the post-exercise recovery kinetics of pH, [PCr], [Pi] and [ADP] contain valuable information about muscle

  20. Cellular fatty acid transport in heart and skeletal muscle as facilitated by proteins

    NARCIS (Netherlands)

    Luiken, J. J.; Schaap, F. G.; van Nieuwenhoven, F. A.; van der Vusse, G. J.; Bonen, A.; Glatz, J. F.

    1999-01-01

    Despite the importance of long-chain fatty acids (FA) as fuels for heart and skeletal muscles, the mechanism of their cellular uptake has not yet been clarified. There is dispute as to whether FA are taken up by the muscle cells via passive diffusion and/or carrier-mediated transport. Kinetic

  1. Influence of step-height and body mass on gastrocnemius muscle fascicle behavior during stair ascent.

    NARCIS (Netherlands)

    Spanjaard, M.; Reeves, N.D.; van Dieen, J.H.; Baltzopoulos, V.; Maganaris, C.N.

    2008-01-01

    To better understand the role of the ankle plantar flexor muscles in stair negotiation, we examined the effects of manipulation of kinematic and kinetic constraints on the behavior of the gastrocnemius medialis (GM) muscle during stair ascent. Ten subjects ascended a four-step staircase at four

  2. Healthy Muscles Matter

    Science.gov (United States)

    ... or lying down, and faster when you’re running or playing sports and your skeletal muscles need more blood to help them do their work. What can go wrong? Injuries Almost everyone has had sore muscles after exercising ...

  3. Kinetics in radiation chemistry

    International Nuclear Information System (INIS)

    Hummel, A.

    1987-01-01

    In this chapter the authors first briefly review the kinetics of first- and second-order processes for continuous and pulsed irradiation, without taking the effects of nonhomogeneous formation of the species into consideration. They also discuss diffusion controlled reactions under conditions where interactions of more than two particles can be neglected, first the kinetics of the diffusion-controlled reaction of randomly generated species (homogeneous reaction) and then that of isolated pairs of reactants. The latter is often called geminate kinetics when dealing with pairs of oppositely charged species; they shall use this term for the kinetics of isolated pairs in general. In the last section they discuss briefly the kinetics of groups of more than two reactants

  4. Oxidative metabolism in muscle.

    OpenAIRE

    Ferrari, M; Binzoni, T; Quaresima, V

    1997-01-01

    Oxidative metabolism is the dominant source of energy for skeletal muscle. Near-infrared spectroscopy allows the non-invasive measurement of local oxygenation, blood flow and oxygen consumption. Although several muscle studies have been made using various near-infrared optical techniques, it is still difficult to interpret the local muscle metabolism properly. The main findings of near-infrared spectroscopy muscle studies in human physiology and clinical medicine are summarized. The advantage...

  5. Non-kinetic capabilities: complementing the kinetic prevalence to targeting

    OpenAIRE

    Ducheine, P.

    2014-01-01

    Targeting is used in military doctrine to describe a military operational way, using (military) means to influence a target (or addressee) in order to achieve designated political and/or military goals. The four factors italicized are used to analyse non-kinetic targeting, complementing our knowledge and understanding of the kinetic prevalence. Paradoxically, non-kinetic targeting is not recognized as a separate concept: kinetic and non-kinetic are intertwined facets of targeting. Kinetic tar...

  6. Exercise and nutritional interventions for improving aging muscle health.

    Science.gov (United States)

    Forbes, Scott C; Little, Jonathan P; Candow, Darren G

    2012-08-01

    Skeletal muscle mass declines with age (i.e., sarcopenia) resulting in muscle weakness and functional limitations. Sarcopenia has been associated with physiological changes in muscle morphology, protein and hormonal kinetics, insulin resistance, inflammation, and oxidative stress. The purpose of this review is to highlight how exercise and nutritional intervention strategies may benefit aging muscle. It is well known that resistance exercise training increases muscle strength and size and evidence also suggests that resistance training can increase mitochondrial content and decrease oxidative stress in older adults. Recent findings suggest that fast-velocity resistance exercise may be an effective intervention for older adults to enhance muscle power and functional capacity. Aerobic exercise training may also benefit aging skeletal muscle by enhancing mitochondrial bioenergetics, improving insulin sensitivity, and/or decreasing oxidative stress. In addition to exercise, creatine monohydrate, milk-based proteins, and essential fatty acids all have biological effects which could enhance some of the physiological adaptations from exercise training in older adults. Additional research is needed to determine whether skeletal muscle adaptations to increased activity in older adults are further enhanced with effective nutritional interventions and whether this is due to enhanced muscle protein synthesis, improved mitochondrial function, and/or a reduced inflammatory response.

  7. Mice deficient in ribosomal protein S6 phosphorylation suffer from muscle weakness that reflects a growth defect and energy deficit.

    Directory of Open Access Journals (Sweden)

    Igor Ruvinsky

    Full Text Available BACKGROUND: Mice, whose ribosomal protein S6 cannot be phosphorylated due to replacement of all five phosphorylatable serine residues by alanines (rpS6(P-/-, are viable and fertile. However, phenotypic characterization of these mice and embryo fibroblasts derived from them, has established the role of these modifications in the regulation of the size of several cell types, as well as pancreatic beta-cell function and glucose homeostasis. A relatively passive behavior of these mice has raised the possibility that they suffer from muscle weakness, which has, indeed, been confirmed by a variety of physical performance tests. METHODOLOGY/PRINCIPAL FINDINGS: A large variety of experimental methodologies, including morphometric measurements of histological preparations, high throughput proteomic analysis, positron emission tomography (PET and numerous biochemical assays, were used in an attempt to establish the mechanism underlying the relative weakness of rpS6(P-/- muscles. Collectively, these experiments have demonstrated that the physical inferiority appears to result from two defects: a a decrease in total muscle mass that reflects impaired growth, rather than aberrant differentiation of myofibers, as well as a diminished abundance of contractile proteins; and b a reduced content of ATP and phosphocreatine, two readily available energy sources. The abundance of three mitochondrial proteins has been shown to diminish in the knockin mouse. However, the apparent energy deficiency in this genotype does not result from a lower mitochondrial mass or compromised activity of enzymes of the oxidative phosphorylation, nor does it reflect a decline in insulin-dependent glucose uptake, or diminution in storage of glycogen or triacylglycerol (TG in the muscle. CONCLUSIONS/SIGNIFICANCE: This study establishes rpS6 phosphorylation as a determinant of muscle strength through its role in regulation of myofiber growth and energy content. Interestingly, a similar

  8. Kinetics of phase transformations

    International Nuclear Information System (INIS)

    Thompson, M.O.; Aziz, M.J.; Stephenson, G.B.

    1992-01-01

    This volume contains papers presented at the Materials Research Society symposium on Kinetics of Phase Transformations held in Boston, Massachusetts from November 26-29, 1990. The symposium provided a forum for research results in an exceptionally broad and interdisciplinary field. Presentations covered nearly every major class of transformations including solid-solid, liquid-solid, transport phenomena and kinetics modeling. Papers involving amorphous Si, a dominant topic at the symposium, are collected in the first section followed by sections on four major areas of transformation kinetics. The symposium opened with joint sessions on ion and electron beam induced transformations in conjunction with the Surface Chemistry and Beam-Solid Interactions: symposium. Subsequent sessions focused on the areas of ordering and nonlinear diffusion kinetics, solid state reactions and amorphization, kinetics and defects of amorphous silicon, and kinetics of melting and solidification. Seven internationally recognized invited speakers reviewed many of the important problems and recent results in these areas, including defects in amorphous Si, crystal to glass transformations, ordering kinetics, solid-state amorphization, computer modeling, and liquid/solid transformations

  9. Irreversible processes kinetic theory

    CERN Document Server

    Brush, Stephen G

    2013-01-01

    Kinetic Theory, Volume 2: Irreversible Processes deals with the kinetic theory of gases and the irreversible processes they undergo. It includes the two papers by James Clerk Maxwell and Ludwig Boltzmann in which the basic equations for transport processes in gases are formulated, together with the first derivation of Boltzmann's ""H-theorem"" and a discussion of this theorem, along with the problem of irreversibility.Comprised of 10 chapters, this volume begins with an introduction to the fundamental nature of heat and of gases, along with Boltzmann's work on the kinetic theory of gases and s

  10. Can fast-twitch muscle fibres be selectively recruited during lengthening contractions? Review and applications to sport movements.

    Science.gov (United States)

    Chalmers, Gordon R

    2008-01-01

    Literature examining the recruitment order of motor units during lengthening (eccentric) contractions was reviewed to determine if fast-twitch motor units can be active while lower threshold slow-twitch motor units are not active. Studies utilizing surface electromyogram (EMG) amplitude, single motor unit activity, spike amplitude-frequency analyses, EMG power spectrum, mechanomyographic, and phosphocreatine-to-creatine ratio (PCr/Cr) techniques were reviewed. Only single motor unit and PCr/Cr data were found to be suitable to address the goals of this review. Nine of ten single motor unit studies, examining joint movement velocities up to 225 degrees/s and forces up to 53% of a maximum voluntary contraction, found that the size principle of motor unit recruitment applied during lengthening contractions. Deviation from the size principle was demonstrated by one study examining movements within a small range of low velocities and modest forces, although other studies examining similar low forces and lengthening velocities reported size-ordered recruitment. The PCr/Cr data demonstrated the activation of all fibre types in lengthening maximal contractions. Most evidence indicates that for lengthening contractions of a wide range of efforts and speeds, fast-twitch muscle fibres cannot be selectively recruited without activity of the slow-twitch fibres of the same muscle.

  11. A muscle stem cell for every muscle: variability of satellite cell biology among different muscle groups

    Science.gov (United States)

    Randolph, Matthew E.; Pavlath, Grace K.

    2015-01-01

    The human body contains approximately 640 individual skeletal muscles. Despite the fact that all of these muscles are composed of striated muscle tissue, the biology of these muscles and their associated muscle stem cell populations are quite diverse. Skeletal muscles are affected differentially by various muscular dystrophies (MDs), such that certain genetic mutations specifically alter muscle function in only a subset of muscles. Additionally, defective muscle stem cells have been implicated in the pathology of some MDs. The biology of muscle stem cells varies depending on the muscles with which they are associated. Here we review the biology of skeletal muscle stem cell populations of eight different muscle groups. Understanding the biological variation of skeletal muscles and their resident stem cells could provide valuable insight into mechanisms underlying the susceptibility of certain muscles to myopathic disease. PMID:26500547

  12. SHORT COMMUNICATION CATALYTIC KINETIC ...

    African Journals Online (AJOL)

    IV) catalyzes the discoloring reaction of DBS-arsenazo oxidized by potassium bromate, a new catalytic kinetic spectrophotometric method for the determination of trace titanium (IV) was developed. The linear range of the determination of ...

  13. Neuromuscular blockade of slow twitch muscle fibres elevates muscle oxygen uptake and energy turnover during submaximal exercise in humans

    DEFF Research Database (Denmark)

    Krustrup, Peter; Secher, Niels; Relu, Mihai U.

    2008-01-01

    We tested the hypothesis that a greater activation of fast-twitch (FT) fibres during dynamic exercise leads to a higher muscle oxygen uptake (VO2 ) and energy turnover as well as a slower muscle on-kinetics. Subjects performed one-legged knee-extensor exercise for 10 min at an intensity of 30 W...... without (CON) and with (CUR) arterial injections of the non-depolarizing neuromuscular blocking agent cisatracurium. In CUR, creatine phosphate (CP) was unaltered in slow twitch (ST) fibres and decreased (P fibres, whereas in CON, CP decreased (P ... at a contraction frequency of 1 Hz, and that the muscle VO2 kinetics is slowed by FT fibre activation....

  14. Child–adult differences in the kinetics of torque development

    Science.gov (United States)

    DOTAN, RAFFY; MITCHELL, CAMERON; COHEN, ROTEM; GABRIEL, DAVID; KLENTROU, PANAGIOTA; FALK, BAREKET

    2013-01-01

    Children have lower size-normalised maximal voluntary force, speed, and power than adults. It has been hypothesised that these and other age-related performance differences are due to lesser type-II motor-unit utilisation in children. This should be manifested as slower force kinetics in explosive muscle contractions. The purpose of this study was to investigate the nature of child–adult force-kinetics differences and whether the latter could support that hypothesis. Untrained boys (n = 20) and men (n = 20) (10.1 ± 1.3 and 22.9 ± 4.4 years, respectively), performed maximal, explosive, isometric elbow flexions and knee extensions on a Biodex dynamometer. Peak torque (MVC), times to 10–100% MVC, and other kinetics parameters were determined. The boys’ body-mass-normalised knee extension MVC, peak rate of torque development, and %MVC at 100 ms were 26, 17 and 23% lower compared with the men and their times to 30% and 80% MVC were 24 and 48% longer, respectively. Elbow flexion kinetics showed similar or greater differences. The findings illuminate boys’ inherent disadvantage in tasks requiring speed or explosive force. It is demonstrated that the extent of the boys–men kinetics disparity cannot be explained by muscle-composition and/or musculo-tendinous-stiffness differences. We suggest therefore that the findings indirectly support children’s lower utilisation of type-II motor units. PMID:23320937

  15. Patterns of shoulder muscle coordination vary between wheelchair propulsion techniques.

    Science.gov (United States)

    Qi, Liping; Wakeling, James; Grange, Simon; Ferguson-Pell, Martin

    2014-05-01

    This study investigated changes in the coordination patterns of shoulder muscles and wheelchair kinetics with different propulsion techniques by comparing wheelchair users' self-selected propulsion patterns with a semicircular pattern adopted after instruction. Wheelchair kinetics data were recorded by Smart(Wheel) on an ergometer, while EMG activity of seven muscles was recorded with surface electrodes on 15 able-bodied inexperienced participants. The performance data in two sessions, first using a self-selected and then the learned semicircular pattern, were compared with a paired t-test. Muscle coordination patterns across seven muscles were analyzed by principal component analysis. The semicircular pattern was characterized by significantly lower push frequency, significantly longer push length, push duration and push distance (p propulsion technique, synergistic muscles were recruited in distinct phases and displayed a clearer separation between activities in the push phase and recovery phase muscles. An instruction session in semicircular propulsion technique is recommended for the initial use of a wheelchair after an injury.

  16. Kinetics of vein graft hyperplasia

    International Nuclear Information System (INIS)

    Zwolak, R.M.; Adams, M.C.; Clowes, A.W.

    1986-01-01

    Human aortocoronary vein grafts fail due to accelerated occlusive disease. The possibility that this is related to cellular hyperplasia was investigated in a rabbit model where kinetics of vein graft thickening, endothelial (EC) repair, and smooth muscle cell (SMC) proliferation were measured from 2 days to 24 weeks after implanting jugular vein segments in the carotid artery. Immediately after graft placement focal EC denudation was observed. These defects were repaired within 1 week and did not recur. By 4 weeks intimal area had increased 30 fold from 0.028 +/- 0.004 to 0.705 +/- 0.021 mm 2 , and a 24 weeks was 0.93 +/- 0.21 mm 2 . This response did not produce a reduction in graft lumen area. EC and SMC thymidine-labeling index were measured by en face and cross-section autoradiography after injection of 3 H-thymidine and perfusion fixation. Despite rapid EC surface repair EC labeling index remained elevated and only returned to normal levels at 12 weeks; SMC labeling was 10 fold greater than baseline even at 24 weeks (0.22% vs 0.02%). SMC mass demonstrated morphometrically increased between 2 and 12 weeks. Intimal thickening in vein grafts is due to SMC proliferation and develops after the EC layer has been restored. In contrast, intimal SMC proliferate in damaged arteries when the EC layer is absent and cease when the EC layer is regenerated

  17. Proteomics of Skeletal Muscle

    DEFF Research Database (Denmark)

    Deshmukh, Atul

    2016-01-01

    , of altered protein expressions profiles and/or their posttranslational modifications (PTMs). Mass spectrometry (MS)-based proteomics offer enormous promise for investigating the molecular mechanisms underlying skeletal muscle insulin resistance and exercise-induced adaptation; however, skeletal muscle......Skeletal muscle is the largest tissue in the human body and plays an important role in locomotion and whole body metabolism. It accounts for ~80% of insulin stimulated glucose disposal. Skeletal muscle insulin resistance, a primary feature of Type 2 diabetes, is caused by a decreased ability...... of muscle to respond to circulating insulin. Physical exercise improves insulin sensitivity and whole body metabolism and remains one of the most promising interventions for the prevention of Type 2 diabetes. Insulin resistance and exercise adaptations in skeletal muscle might be a cause, or consequence...

  18. Muscles, exercise and obesity

    DEFF Research Database (Denmark)

    Pedersen, Bente K; Febbraio, Mark A

    2012-01-01

    During the past decade, skeletal muscle has been identified as a secretory organ. Accordingly, we have suggested that cytokines and other peptides that are produced, expressed and released by muscle fibres and exert either autocrine, paracrine or endocrine effects should be classified as myokines....... The finding that the muscle secretome consists of several hundred secreted peptides provides a conceptual basis and a whole new paradigm for understanding how muscles communicate with other organs, such as adipose tissue, liver, pancreas, bones and brain. However, some myokines exert their effects within...... the muscle itself. Thus, myostatin, LIF, IL-6 and IL-7 are involved in muscle hypertrophy and myogenesis, whereas BDNF and IL-6 are involved in AMPK-mediated fat oxidation. IL-6 also appears to have systemic effects on the liver, adipose tissue and the immune system, and mediates crosstalk between intestinal...

  19. Bioenergetics and ATP Synthesis during Exercise: Role of Group III/IV Muscle Afferents.

    Science.gov (United States)

    Broxterman, Ryan M; Layec, Gwenael; Hureau, Thomas J; Morgan, David E; Bledsoe, Amber D; Jessop, Jacob E; Amann, Markus; Richardson, Russell S

    2017-12-01

    The purpose of this study was to investigate the role of the group III/IV muscle afferents in the bioenergetics of exercising skeletal muscle beyond constraining the magnitude of metabolic perturbation. Eight healthy men performed intermittent isometric knee-extensor exercise to task failure at ~58% maximal voluntary contraction under control conditions (CTRL) and with lumbar intrathecal fentanyl to attenuate group III/IV leg muscle afferents (FENT). Intramuscular concentrations of phosphocreatine (PCr), inorganic phosphate (Pi), diprotonated phosphate (H2PO4), adenosine triphosphate (ATP), and pH were determined using phosphorous magnetic resonance spectroscopy (P-MRS). The magnitude of metabolic perturbation was significantly greater in FENT compared with CTRL for [Pi] (37.8 ± 16.8 vs 28.6 ± 8.6 mM), [H2PO4] (24.3 ± 12.2 vs 17.9 ± 7.1 mM), and [ATP] (75.8% ± 17.5% vs 81.9% ± 15.8% of baseline), whereas there was no significant difference in [PCr] (4.5 ± 2.4 vs 4.4 ± 2.3 mM) or pH (6.51 ± 0.10 vs 6.54 ± 0.14). The rate of perturbation in [PCr], [Pi], [H2PO4], and pH was significantly faster in FENT compared with CTRL. Oxidative ATP synthesis was not significantly different between conditions. However, anaerobic ATP synthesis, through augmented creatine kinase and glycolysis reactions, was significantly greater in FENT than in CTRL, resulting in a significantly greater ATP cost of contraction (0.049 ± 0.016 vs 0.038 ± 0.010 mM·min·N). Group III/IV muscle afferents not only constrain the magnitude of perturbation in intramuscular Pi, H2PO4, and ATP during small muscle mass exercise but also seem to play a role in maintaining efficient skeletal muscle contractile function in men.

  20. Effect of ionizing radiation on catalytic properties of Ca2+-ATP-ase from sarcoplasmic reticulum of skeletal muscle

    International Nuclear Information System (INIS)

    Bagel', I.M.; Shafranovskaya, E.V.; Gorokh, G.A.; Markova, A.G.

    1999-01-01

    It was studied kinetic and thermodynamic characteristics of Ca 2+ -ATP-ase of rat skeletal muscle (membranes of sarcoplasmic reticulum) after irradiation in doses 0,5, 4,0 and 8,0 Gy. It was shown that external gamma-irradiation at different doses changed kinetic and thermodynamic characteristics of the enzyme of sarcoplasmic reticulum membranes of skeletal muscle. These alterations probably correlate with disbalance of hormonal regulation of intracellular calcium metabolism and changes in membrane structure and functions

  1. Accessory piriformis muscle

    Directory of Open Access Journals (Sweden)

    Sedat Develi

    2017-03-01

    Full Text Available Piriformis muscle originates from facies pelvica of sacrum and inserts on the trochanter major. It is one of the lateral rotator muscles of the hip and a landmark point in the gluteal region since n. ischiadicus descends to the thigh by passing close to the muscle. This contiguity may be associated with the irritation of the nerve which is known as piriformis syndrome. A rare anatomic variation of the muscle which observed on 74 years old male cadaver is discussed in this case report. [Cukurova Med J 2017; 42(1.000: 182-183

  2. Contraction and AICAR Stimulate IL-6 Vesicle Depletion From Skeletal Muscle Fibers In Vivo

    DEFF Research Database (Denmark)

    Lauritzen, Hans P M M; Brandauer, Josef; Schjerling, Peter

    2013-01-01

    muscle fibers and in live animals in vivo. Using confocal imaging to visualize endogenous IL-6 protein in fixed muscle fibers, we found IL-6 in small vesicle structures distributed throughout the fibers under basal (resting) conditions. To determine the kinetics of IL-6 secretion, intact quadriceps...... muscles were transfected with enhanced green fluorescent protein (EGFP)-tagged IL-6 (IL-6-EGFP), and 5 days later anesthetized mice were imaged before and after muscle contractions in situ. Contractions decreased IL-6-EGFP-containing vesicles and protein by 62% (P

  3. Relativistic Chiral Kinetic Theory

    International Nuclear Information System (INIS)

    Stephanov, Mikhail

    2016-01-01

    This very brief review of the recent progress in chiral kinetic theory is based on the results of Refs. [J.-Y. Chen, D. T. Son, M. A. Stephanov, H.-U. Yee, Y. Yin, Lorentz Invariance in Chiral Kinetic Theory, Phys. Rev. Lett. 113 (18) (2014) 182302. doi: (10.1103/PhysRevLett.113.182302); J.-Y. Chen, D. T. Son, M. A. Stephanov, Collisions in Chiral Kinetic Theory, Phys. Rev. Lett. 115 (2) (2015) 021601. doi: (10.1103/PhysRevLett.115.021601); M. A. Stephanov, H.-U. Yee, The no-drag frame for anomalous chiral fluid, Phys. Rev. Lett. 116 (12) (2016) 122302. doi: (10.1103/PhysRevLett.116.122302)].

  4. Relativistic Chiral Kinetic Theory

    Energy Technology Data Exchange (ETDEWEB)

    Stephanov, Mikhail

    2016-12-15

    This very brief review of the recent progress in chiral kinetic theory is based on the results of Refs. [J.-Y. Chen, D. T. Son, M. A. Stephanov, H.-U. Yee, Y. Yin, Lorentz Invariance in Chiral Kinetic Theory, Phys. Rev. Lett. 113 (18) (2014) 182302. doi: (10.1103/PhysRevLett.113.182302); J.-Y. Chen, D. T. Son, M. A. Stephanov, Collisions in Chiral Kinetic Theory, Phys. Rev. Lett. 115 (2) (2015) 021601. doi: (10.1103/PhysRevLett.115.021601); M. A. Stephanov, H.-U. Yee, The no-drag frame for anomalous chiral fluid, Phys. Rev. Lett. 116 (12) (2016) 122302. doi: (10.1103/PhysRevLett.116.122302)].

  5. Erbium hydride decomposition kinetics.

    Energy Technology Data Exchange (ETDEWEB)

    Ferrizz, Robert Matthew

    2006-11-01

    Thermal desorption spectroscopy (TDS) is used to study the decomposition kinetics of erbium hydride thin films. The TDS results presented in this report are analyzed quantitatively using Redhead's method to yield kinetic parameters (E{sub A} {approx} 54.2 kcal/mol), which are then utilized to predict hydrogen outgassing in vacuum for a variety of thermal treatments. Interestingly, it was found that the activation energy for desorption can vary by more than 7 kcal/mol (0.30 eV) for seemingly similar samples. In addition, small amounts of less-stable hydrogen were observed for all erbium dihydride films. A detailed explanation of several approaches for analyzing thermal desorption spectra to obtain kinetic information is included as an appendix.

  6. Relativistic Kinetic Theory

    Science.gov (United States)

    Vereshchagin, Gregory V.; Aksenov, Alexey G.

    2017-02-01

    Preface; Acknowledgements; Acronyms and definitions; Introduction; Part I. Theoretical Foundations: 1. Basic concepts; 2. Kinetic equation; 3. Averaging; 4. Conservation laws and equilibrium; 5. Relativistic BBGKY hierarchy; 6. Basic parameters in gases and plasmas; Part II. Numerical Methods: 7. The basics of computational physics; 8. Direct integration of Boltzmann equations; 9. Multidimensional hydrodynamics; Part III. Applications: 10. Wave dispersion in relativistic plasma; 11. Thermalization in relativistic plasma; 12. Kinetics of particles in strong fields; 13. Compton scattering in astrophysics and cosmology; 14. Self-gravitating systems; 15. Neutrinos, gravitational collapse and supernovae; Appendices; Bibliography; Index.

  7. Quantum kinetic theory

    CERN Document Server

    Bonitz, Michael

    2016-01-01

    This book presents quantum kinetic theory in a comprehensive way. The focus is on density operator methods and on non-equilibrium Green functions. The theory allows to rigorously treat nonequilibrium dynamics in quantum many-body systems. Of particular interest are ultrafast processes in plasmas, condensed matter and trapped atoms that are stimulated by rapidly developing experiments with short pulse lasers and free electron lasers. To describe these experiments theoretically, the most powerful approach is given by non-Markovian quantum kinetic equations that are discussed in detail, including computational aspects.

  8. Muscle phosphorylase kinase deficiency

    DEFF Research Database (Denmark)

    Preisler, N; Orngreen, M C; Echaniz-Laguna, A

    2012-01-01

    To examine metabolism during exercise in 2 patients with muscle phosphorylase kinase (PHK) deficiency and to further define the phenotype of this rare glycogen storage disease (GSD).......To examine metabolism during exercise in 2 patients with muscle phosphorylase kinase (PHK) deficiency and to further define the phenotype of this rare glycogen storage disease (GSD)....

  9. the sternalis muscle

    African Journals Online (AJOL)

    2009-08-17

    Aug 17, 2009 ... CASE REPORT. CASE. 72. SA JOURNAL OF RADIOLOGY • August 2009. CASE R. Introduction ... tion is being given to imaging the medial breast, and the sternalis muscle will be revealed with increasing ... The origin of this muscle is uncertain, with pectoralis major, rectus abdominus and sternomastoid ...

  10. The hamstring muscle complex

    NARCIS (Netherlands)

    van der Made, A. D.; Wieldraaijer, T.; Kerkhoffs, G. M.; Kleipool, R. P.; Engebretsen, L.; van Dijk, C. N.; Golanó, P.

    2015-01-01

    The anatomical appearance of the hamstring muscle complex was studied to provide hypotheses for the hamstring injury pattern and to provide reference values of origin dimensions, muscle length, tendon length, musculotendinous junction (MTJ) length as well as width and length of a tendinous

  11. Muscle as a secretory organ

    DEFF Research Database (Denmark)

    Pedersen, Bente K

    2013-01-01

    Skeletal muscle is the largest organ in the body. Skeletal muscles are primarily characterized by their mechanical activity required for posture, movement, and breathing, which depends on muscle fiber contractions. However, skeletal muscle is not just a component in our locomotor system. Recent e...... proteins produced by skeletal muscle are dependent upon contraction. Therefore, it is likely that myokines may contribute in the mediation of the health benefits of exercise.......Skeletal muscle is the largest organ in the body. Skeletal muscles are primarily characterized by their mechanical activity required for posture, movement, and breathing, which depends on muscle fiber contractions. However, skeletal muscle is not just a component in our locomotor system. Recent...... evidence has identified skeletal muscle as a secretory organ. We have suggested that cytokines and other peptides that are produced, expressed, and released by muscle fibers and exert either autocrine, paracrine, or endocrine effects should be classified as "myokines." The muscle secretome consists...

  12. 31P magnetization transfer measurements of Pi→ATP flux in exercising human muscle.

    Science.gov (United States)

    Sleigh, Alison; Savage, David B; Williams, Guy B; Porter, David; Carpenter, T Adrian; Brindle, Kevin M; Kemp, Graham J

    2016-03-15

    Fundamental criticisms have been made over the use of (31)P magnetic resonance spectroscopy (MRS) magnetization transfer estimates of inorganic phosphate (Pi)→ATP flux (VPi-ATP) in human resting skeletal muscle for assessing mitochondrial function. Although the discrepancy in the magnitude of VPi-ATP is now acknowledged, little is known about its metabolic determinants. Here we use a novel protocol to measure VPi-ATP in human exercising muscle for the first time. Steady-state VPi-ATP was measured at rest and over a range of exercise intensities and compared with suprabasal oxidative ATP synthesis rates estimated from the initial rates of postexercise phosphocreatine resynthesis (VATP). We define a surplus Pi→ATP flux as the difference between VPi-ATP and VATP. The coupled reactions catalyzed by the glycolytic enzymes GAPDH and phosphoglycerate kinase (PGK) have been shown to catalyze measurable exchange between ATP and Pi in some systems and have been suggested to be responsible for this surplus flux. Surplus VPi-ATP did not change between rest and exercise, even though the concentrations of Pi and ADP, which are substrates for GAPDH and PGK, respectively, increased as expected. However, involvement of these enzymes is suggested by correlations between absolute and surplus Pi→ATP flux, both at rest and during exercise, and the intensity of the phosphomonoester peak in the (31)P NMR spectrum. This peak includes contributions from sugar phosphates in the glycolytic pathway, and changes in its intensity may indicate changes in downstream glycolytic intermediates, including 3-phosphoglycerate, which has been shown to influence the exchange between ATP and Pi catalyzed by GAPDH and PGK. Copyright © 2016 the American Physiological Society.

  13. The pH heterogeneity in human calf muscle during neuromuscular electrical stimulation.

    Science.gov (United States)

    Stutzig, Norman; Rzanny, Reinhard; Moll, Kevin; Gussew, Alexander; Reichenbach, Jürgen R; Siebert, Tobias

    2017-06-01

    The aim of the study was to examine pH heterogeneity during fatigue induced by neuromuscular electrical stimulation (NMES) using phosphorus magnetic resonance spectroscopy ( 31 P-MRS). It is hypothesized that three pH components would occur in the 31 P-MRS during fatigue, representing three fiber types. The medial gastrocnemius of eight subjects was stimulated within a 3-Tesla whole body MRI scanner. The maximal force during stimulation (F stim ) was examined by a pressure sensor. Phosphocreatine (PCr), adenosintriphosphate, inorganic phosphate (Pi), and the corresponding pH were estimated by a nonvolume-selective 31 P-MRS using a small loop coil at rest and during fatigue. During fatigue, F stim and PCr decreased to 27% and 33% of their initial levels, respectively. In all cases, the Pi peak increased when NMES was started and split into three different peaks. Based on the single Pi peaks during fatigue, an alkaline (6.76 ± 0.08), a medium (6.40 ± 0.06), and an acidic (6.09 ± 0.05) pH component were observed compared to the pH (7.02 ± 0.02) at rest. It is suggested that NMES is able to induce pH heterogeneity in the medial gastrocnemius, and that the single Pi peaks represent the different muscle fiber types of the skeletal muscle. Magn Reson Med 77:2097-2106, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

  14. A muscle model for hybrid muscle activation

    Directory of Open Access Journals (Sweden)

    Klauer Christian

    2015-09-01

    Full Text Available To develop model-based control strategies for Functional Electrical Stimulation (FES in order to support weak voluntary muscle contractions, a hybrid model for describing joint motions induced by concurrent voluntary-and FES induced muscle activation is proposed. It is based on a Hammerstein model – as commonly used in feedback controlled FES – and exemplarily applied to describe the shoulder abduction joint angle. Main component of a Hammerstein muscle model is usually a static input nonlinearity depending on the stimulation intensity. To additionally incorporate voluntary contributions, we extended the static non-linearity by a second input describing the intensity of the voluntary contribution that is estimated by electromyography (EMG measurements – even during active FES. An Artificial Neural Network (ANN is used to describe the static input non-linearity. The output of the ANN drives a second-order linear dynamical system that describes the combined muscle activation and joint angle dynamics. The tunable parameters are adapted to the individual subject by a system identification approach using previously recorded I/O-data. The model has been validated in two healthy subjects yielding RMS values for the joint angle error of 3.56° and 3.44°, respectively.

  15. Oxidative desulfurization: kinetic modelling.

    Science.gov (United States)

    Dhir, S; Uppaluri, R; Purkait, M K

    2009-01-30

    Increasing environmental legislations coupled with enhanced production of petroleum products demand, the deployment of novel technologies to remove organic sulfur efficiently. This work represents the kinetic modeling of ODS using H(2)O(2) over tungsten-containing layered double hydroxide (LDH) using the experimental data provided by Hulea et al. [V. Hulea, A.L. Maciuca, F. Fajula, E. Dumitriu, Catalytic oxidation of thiophenes and thioethers with hydrogen peroxide in the presence of W-containing layered double hydroxides, Appl. Catal. A: Gen. 313 (2) (2006) 200-207]. The kinetic modeling approach in this work initially targets the scope of the generation of a superstructure of micro-kinetic reaction schemes and models assuming Langmuir-Hinshelwood (LH) and Eley-Rideal (ER) mechanisms. Subsequently, the screening and selection of above models is initially based on profile-based elimination of incompetent schemes followed by non-linear regression search performed using the Levenberg-Marquardt algorithm (LMA) for the chosen models. The above analysis inferred that Eley-Rideal mechanism describes the kinetic behavior of ODS process using tungsten-containing LDH, with adsorption of reactant and intermediate product only taking place on the catalyst surface. Finally, an economic index is presented that scopes the economic aspects of the novel catalytic technology with the parameters obtained during regression analysis to conclude that the cost factor for the catalyst is 0.0062-0.04759 US $ per barrel.

  16. Oxidative desulfurization: Kinetic modelling

    International Nuclear Information System (INIS)

    Dhir, S.; Uppaluri, R.; Purkait, M.K.

    2009-01-01

    Increasing environmental legislations coupled with enhanced production of petroleum products demand, the deployment of novel technologies to remove organic sulfur efficiently. This work represents the kinetic modeling of ODS using H 2 O 2 over tungsten-containing layered double hydroxide (LDH) using the experimental data provided by Hulea et al. [V. Hulea, A.L. Maciuca, F. Fajula, E. Dumitriu, Catalytic oxidation of thiophenes and thioethers with hydrogen peroxide in the presence of W-containing layered double hydroxides, Appl. Catal. A: Gen. 313 (2) (2006) 200-207]. The kinetic modeling approach in this work initially targets the scope of the generation of a superstructure of micro-kinetic reaction schemes and models assuming Langmuir-Hinshelwood (LH) and Eley-Rideal (ER) mechanisms. Subsequently, the screening and selection of above models is initially based on profile-based elimination of incompetent schemes followed by non-linear regression search performed using the Levenberg-Marquardt algorithm (LMA) for the chosen models. The above analysis inferred that Eley-Rideal mechanism describes the kinetic behavior of ODS process using tungsten-containing LDH, with adsorption of reactant and intermediate product only taking place on the catalyst surface. Finally, an economic index is presented that scopes the economic aspects of the novel catalytic technology with the parameters obtained during regression analysis to conclude that the cost factor for the catalyst is 0.0062-0.04759 US $ per barrel

  17. Modeling chemical kinetics graphically

    NARCIS (Netherlands)

    Heck, A.

    2012-01-01

    In literature on chemistry education it has often been suggested that students, at high school level and beyond, can benefit in their studies of chemical kinetics from computer supported activities. Use of system dynamics modeling software is one of the suggested quantitative approaches that could

  18. CATALYTIC KINETIC SPECTROPHOTOMETRIC DETERMINATION ...

    African Journals Online (AJOL)

    Preferred Customer

    acetylchlorophosphonazo(CPApA) by hydrogen peroxide in 0.10 M phosphoric acid. A novel catalytic kinetic-spectrophotometric method is proposed for the determination of copper based on this principle. Copper(II) can be determined spectrophotometrically ...

  19. Kinetic energy budget details

    Indian Academy of Sciences (India)

    Abstract. This paper presents the detailed turbulent kinetic energy budget and higher order statistics of flow behind a surface-mounted rib with and without superimposed acoustic excitation. Pattern recognition technique is used to determine the large-scale structure magnitude. It is observed that most of the turbulence ...

  20. Point kinetics modeling

    International Nuclear Information System (INIS)

    Kimpland, R.H.

    1996-01-01

    A normalized form of the point kinetics equations, a prompt jump approximation, and the Nordheim-Fuchs model are used to model nuclear systems. Reactivity feedback mechanisms considered include volumetric expansion, thermal neutron temperature effect, Doppler effect and void formation. A sample problem of an excursion occurring in a plutonium solution accidentally formed in a glovebox is presented

  1. Tritium kinetics in a freshwater marsh ecosystem

    International Nuclear Information System (INIS)

    Adams, L.W.

    1976-01-01

    Ten curies of tritium (as tritiated water, HTO) were applied to a 2-ha enclosed Lake Erie marsh in northwestern Ohio on 29 October 1973. Tritium kinetics in the marsh water, bottom sediment, and selected aquatic plants and animals were determined. Following HTO application, peak tritium levels in the sediment were observed on day 13 in the top 1-cm layer, on day 27 at the 5-cm depth, and on day 64 at the 10-cm depth. Peak levels at 15 and 20 cm were not discernible, although there was some movement of HTO to the 20-cm depth. A model based on diffusion theory described tritium movement through the sediment. Unbound and bound tritium levels in curly-leaf pondweed (Potamogeton crispus), pickerelweed (Pontederia cordata), and smartweed (Polygonum lapathifolium) generally tended to follow tritium levels in marsh water. The unbound tritium:marsh water tritium ratio was significantly larger (P < 0.001) in curly-leaf pondweed than in either of the two emergents. Tritium uptake into the unbound compartments of crayfish (Procambarus blandingi), carp (Cyprinus carpio), and bluegills (Lepomis macrochirus) was rapid. For crayfish, maximum HTO levels were observed on days 3 and 2 for viscera and muscle, respectively. Unbound HTO in carp viscera peaked on day 2, and levels in carp muscle reached a maximum in 4 hours. Maximum levels of unbound HTO in bluegill viscera and muscle were observed on day 1. After peak levels were obtained, unbound HTO paralleled marsh water HTO activity in all species. Tritium uptake into the bound compartments was not as rapid nor were the levels as high as for unbound HTO in any of the species. Peak bound levels in crayfish viscera were observed on day 20 and maximum levels in muscle were noted on day 10. Bound tritium in carp viscera and muscle reached maximum levels on day 20. In bluegills, peaks were reached on days 7 and 5 for viscera and muscle, respectively. Bound tritium in all species decreased following maximum levels

  2. Training-induced adaptation of oxidative phosphorylation in skeletal muscles.

    Science.gov (United States)

    Korzeniewski, Bernard; Zoladz, Jerzy A

    2003-08-15

    Muscle training/conditioning improves the adaptation of oxidative phosphorylation in skeletal muscles to physical exercise. However, the mechanisms underlying this adaptation are still not understood fully. By quantitative analysis of the existing experimental results, we show that training-induced acceleration of oxygen-uptake kinetics at the onset of exercise and improvement of ATP/ADP stability due to physical training are mainly caused by an increase in the amount of mitochondrial proteins and by an intensification of the parallel activation of ATP usage and ATP supply (increase in direct stimulation of oxidative phosphorylation complexes accompanying stimulation of ATP consumption) during exercise.

  3. A mini-overview of single muscle fibre mechanics: the effects of age, inactivity and exercise in animals and humans.

    Science.gov (United States)

    Jee, Hyunseok; Kim, Jong-Hee

    2017-09-05

    Many basic movements of living organisms are dependent on muscle function. Muscle function allows for the coordination and harmonious integrity of movement that is necessary for various biological processes. Gross and fine motor skills are both regulated at the micro-level (single muscle fibre level), controlled by neuronal regulation, and it is therefore important to understand muscle function at both micro- and macro-levels to understand the overall movement of living organisms. Single muscle mechanics and the cellular environment of muscles fundamentally allow for the harmonious movement of our bodies. Indeed, a clear understanding of the functionality of muscle at the micro-level is indispensable for explaining muscular function at the macro-(whole gross muscle) level. By investigating single muscle fibre mechanics, we can also learn how other factors such Ca2+ kinetics, enzyme activity and contractile proteins can contribute to muscle mechanics at the micro- and macro-levels. Further, we can also describe how aging affects the capacity of skeletal muscle cells, as well as how exercise can prevent aging-based sarcopenia and frailty. The purpose of this review is to introduce and summarise the current knowledge of single muscle fibre mechanics in light of aging and inactivity. We then describe how exercise mitigates negative muscle adaptations that occur under those circumstances. In addition, single muscle fibre mechanics in both animal and human models are discussed.

  4. Contraction and AICAR stimulate IL-6 vesicle depletion from skeletal muscle fibers in vivo.

    Science.gov (United States)

    Lauritzen, Hans P M M; Brandauer, Josef; Schjerling, Peter; Koh, Ho-Jin; Treebak, Jonas T; Hirshman, Michael F; Galbo, Henrik; Goodyear, Laurie J

    2013-09-01

    Recent studies suggest that interleukin 6 (IL-6) is released from contracting skeletal muscles; however, the cellular origin, secretion kinetics, and signaling mechanisms regulating IL-6 secretion are unknown. To address these questions, we developed imaging methodology to study IL-6 in fixed mouse muscle fibers and in live animals in vivo. Using confocal imaging to visualize endogenous IL-6 protein in fixed muscle fibers, we found IL-6 in small vesicle structures distributed throughout the fibers under basal (resting) conditions. To determine the kinetics of IL-6 secretion, intact quadriceps muscles were transfected with enhanced green fluorescent protein (EGFP)-tagged IL-6 (IL-6-EGFP), and 5 days later anesthetized mice were imaged before and after muscle contractions in situ. Contractions decreased IL-6-EGFP-containing vesicles and protein by 62% (P contraction. However, contraction-mediated IL-6-EGFP reduction was normal in muscle-specific AMP-activated protein kinase (AMPK) α2-inactive transgenic mice. In contrast, the AMPK activator AICAR decreased IL-6-EGFP vesicles, an effect that was inhibited in the transgenic mice. In conclusion, resting skeletal muscles contain IL-6-positive vesicles that are expressed throughout myofibers. Contractions stimulate the rapid reduction of IL-6 in myofibers, occurring through an AMPKα2-independent mechanism. This novel imaging methodology clearly establishes IL-6 as a contraction-stimulated myokine and can be used to characterize the secretion kinetics of other putative myokines.

  5. Aging augments the impact of influenza respiratory tract infection on mobility impairments, muscle-localized inflammation, and muscle atrophy.

    Science.gov (United States)

    Bartley, Jenna M; Pan, Sarah J; Keilich, Spencer R; Hopkins, Jacob W; Al-Naggar, Iman M; Kuchel, George A; Haynes, Laura

    2016-04-01

    Although the influenza virus only infects the respiratory system, myalgias are commonly experienced during infection. In addition to a greater risk of hospitalization and death, older adults are more likely to develop disability following influenza infection; however, this relationship is understudied. We hypothesized that upon challenge with influenza, aging would be associated with functional impairments, as well as upregulation of skeletal muscle inflammatory and atrophy genes. Infected young and aged mice demonstrated decreased mobility and altered gait kinetics. These declines were more prominent in hind limbs and in aged mice. Skeletal muscle expression of genes involved in inflammation, as well as muscle atrophy and proteolysis, increased during influenza infection with an elevated and prolonged peak in aged mice. Infection also decreased expression of positive regulators of muscle mass and myogenesis components to a greater degree in aged mice. Gene expression correlated to influenza-induced body mass loss, although evidence did not support direct muscle infection. Overall, influenza leads to mobility impairments with induction of inflammatory and muscle degradation genes and downregulation of positive regulators of muscle. These effects are augmented and prolonged with aging, providing a molecular link between influenza infection, decreased resilience and increased risk of disability in the elderly.

  6. Muscles and their myokines.

    Science.gov (United States)

    Pedersen, Bente Klarlund

    2011-01-15

    In the past, the role of physical activity as a life-style modulating factor has been considered as that of a tool to balance energy intake. Although it is important to avoid obesity, physical inactivity should be discussed in a much broader context. There is accumulating epidemiological evidence that a physically active life plays an independent role in the protection against type 2 diabetes, cardiovascular diseases, cancer, dementia and even depression. For most of the last century, researchers sought a link between muscle contraction and humoral changes in the form of an 'exercise factor', which could be released from skeletal muscle during contraction and mediate some of the exercise-induced metabolic changes in other organs such as the liver and the adipose tissue. We have suggested that cytokines or other peptides that are produced, expressed and released by muscle fibres and exert autocrine, paracrine or endocrine effects should be classified as 'myokines'. Given that skeletal muscle is the largest organ in the human body, our discovery that contracting skeletal muscle secretes proteins sets a novel paradigm: skeletal muscle is an endocrine organ producing and releasing myokines, which work in a hormone-like fashion, exerting specific endocrine effects on other organs. Other myokines work via paracrine mechanisms, exerting local effects on signalling pathways involved in muscle metabolism. It has been suggested that myokines may contribute to exercise-induced protection against several chronic diseases.

  7. Functional Echomyography: thickness, ecogenicity, contraction and perfusion of the LMN denervated human muscle before and during h-bFES

    Directory of Open Access Journals (Sweden)

    Riccardo Zanato

    2010-03-01

    Full Text Available Permanent denervated muscles were evaluated by ultrasound to monitor changes in morphology, thickness, contraction-relaxation kinetics and perfusion due to the electrical stimulation program of the Rise2-Italy project. In a case of monolateral lesion, morphology and ultrasonographic structure of the denervated muscles changed during the period of stimulation from a pattern typical of complete denervation-induced muscle atrophy to a pattern which might be considered “normal” when detected in an old patient. Thickness improved significantly more in the middle third of the denervated muscle, reaching the same value as the contralateral innervated muscle. Contraction-relaxation kinetics, measured by recording the muscle movements during electrical stimulation, showed an abnormal behavior of the chronically denervated muscle during the relaxation phase, which resulted to be significantly longer than in normal muscle. The long-term denervated muscles analyzed with Echo Doppler showed at rest a low resistance arterial flow that became pulsed during and after electrical stimulation. As expected, the ultra sound measured electrical stimulation-induced hyperemia lasted longer than the stimulation period. The higher than normal energy of the delivered electrical stimuli of the Vienna home-based Functional Electrical Stimulation strategy (h-b FES demonstrate that the explored muscles were still almost completely denervated during the one-year of training. In conclusion, this pilot study confirms the usefulness of Functional Echomyography in the follow-up and the positive effects of h-b FES of denervated muscles.

  8. Is Walking Capacity in Subjects with Multiple Sclerosis Primarily Related to Muscle Oxidative Capacity or Maximal Muscle Strength? A Pilot Study

    Directory of Open Access Journals (Sweden)

    Dominique Hansen

    2014-01-01

    Full Text Available Background and Purpose. Walking capacity is reduced in subjects with multiple sclerosis (MS. To develop effective exercise interventions to enhance walking capacity, it is important to determine the impact of factors, modifiable by exercise intervention (maximal muscle strength versus muscle oxidative capacity, on walking capacity. The purpose of this pilot study is to discriminate between the impact of maximal muscle strength versus muscle oxidative capacity on walking capacity in subjects with MS. Methods. From 24 patients with MS, muscle oxidative capacity was determined by calculation of exercise-onset oxygen uptake kinetics (mean response time during submaximal exercise bouts. Maximal muscle strength (isometric knee extension and flexion peak torque was assessed on dynamometer. All subjects completed a 6-minute walking test. Relationships between walking capacity (as a percentage of normal value and muscle strength (of knee flexors and extensors versus muscle oxidative capacity were assessed in multivariate regression analyses. Results. The expanded disability status score (EDSS showed a significant univariate correlation (r=-0.70, P<0.004 with walking capacity. In multivariate regression analyses, EDSS and mean response time, but not muscle strength, were independently related to walking capacity (P<0.05. Conclusions. Walking distance is, next to disability level and not taking neurologic symptoms/deficits into account, primarily related to muscle oxidative capacity in subjects with MS. Additional study is needed to further examine/verify these findings.

  9. Muscle Bioenergetic Considerations for Intrinsic Laryngeal Skeletal Muscle Physiology

    Science.gov (United States)

    Sandage, Mary J.; Smith, Audrey G.

    2017-01-01

    Purpose: Intrinsic laryngeal skeletal muscle bioenergetics, the means by which muscles produce fuel for muscle metabolism, is an understudied aspect of laryngeal physiology with direct implications for voice habilitation and rehabilitation. The purpose of this review is to describe bioenergetic pathways identified in limb skeletal muscle and…

  10. Muscle contraction and force

    DEFF Research Database (Denmark)

    Brüggemann, Dagmar Adeline; Risbo, Jens; Pierzynowski, Stefan G.

    2008-01-01

    Muscle contraction studies often focus solely on myofibres and the proteins known to be involved in the processes of sarcomere shortening and cross-bridge cycling, but skeletal muscle also comprises a very elaborate ancillary network of capillaries, which not only play a vital role in terms...... of nutrient delivery and waste product removal, but are also tethered to surrounding fibres by collagen "wires". This paper therefore addresses aspects of the ancillary network of skeletal muscle at both a microscopic and functional level in order to better understand its role holistically as a considerable...

  11. LLNL Chemical Kinetics Modeling Group

    Energy Technology Data Exchange (ETDEWEB)

    Pitz, W J; Westbrook, C K; Mehl, M; Herbinet, O; Curran, H J; Silke, E J

    2008-09-24

    The LLNL chemical kinetics modeling group has been responsible for much progress in the development of chemical kinetic models for practical fuels. The group began its work in the early 1970s, developing chemical kinetic models for methane, ethane, ethanol and halogenated inhibitors. Most recently, it has been developing chemical kinetic models for large n-alkanes, cycloalkanes, hexenes, and large methyl esters. These component models are needed to represent gasoline, diesel, jet, and oil-sand-derived fuels.

  12. Painful unilateral temporalis muscle enlargement: reactive masticatory muscle hypertrophy.

    Science.gov (United States)

    Katsetos, Christos D; Bianchi, Michael A; Jaffery, Fizza; Koutzaki, Sirma; Zarella, Mark; Slater, Robert

    2014-06-01

    An instance of isolated unilateral temporalis muscle hypertrophy (reactive masticatory muscle hypertrophy with fiber type 1 predominance) confirmed by muscle biopsy with histochemical fiber typing and image analysis in a 62 year-old man is reported. The patient presented with bruxism and a painful swelling of the temple. Absence of asymmetry or other abnormalities of the craniofacial skeleton was confirmed by magnetic resonance imaging and cephalometric analyses. The patient achieved symptomatic improvement only after undergoing botulinum toxin injections. Muscle biopsy is key in the diagnosis of reactive masticatory muscle hypertrophy and its distinction from masticatory muscle myopathy (hypertrophic branchial myopathy) and other non-reactive causes of painful asymmetric temporalis muscle enlargement.

  13. Measuring perfusion and bioenergetics simultaneously in mouse skeletal muscle: a multi-parametric functional-NMR approach

    International Nuclear Information System (INIS)

    Baligand, C.; Wary, C.; Menard, J.C.; Giacomini, E.; Carlier, P.G.; Baligand, C.; Wary, C.; Menard, J.C.; Hogrel, J.Y.; Carlier, P.G.; Hogrel, J.Y.

    2011-01-01

    A totally noninvasive set-up was developed for comprehensive NMR evaluation of mouse skeletal muscle function in vivo. Dynamic pulsed arterial spin labeling-NMRI perfusion and blood oxygenation level-dependent (BOLD) signal measurements were interleaved with 31 P NMRS to measure both vascular response and oxidative capacities during stimulated exercise and subsequent recovery. Force output was recorded with a dedicated ergometer. Twelve exercise bouts were performed. The perfusion, BOLD signal, pH and force-time integral were obtained from mouse legs for each exercise. All reached a steady state after the second exercise, justifying the pointwise summation of the last 10 exercises to compensate for the limited 31 P signal. In this way, a high temporal resolution of 2.5 s was achieved to provide a time constant for phosphocreatine (PCr) recovery (tPCr). The higher signal-to-noise ratio improved the precision of τ(PCr) measurement [coefficient of variation (CV)1/416.5% vs CV1/449.2% for a single exercise at a resolution of 30 s]. Inter-animal summation confirmed that τ(PCr) was stable at steady state, but shorter (89.3W8.6 s) than after the first exercise (148 s, p≤0.05). This novel experimental approach provides an assessment of muscle vascular response simultaneously to energetic function in vivo. Its pertinence was illustrated by observing the establishment of a metabolic steady state. This comprehensive tool offers new perspectives for the study of muscle pathology in mice models. (authors)

  14. Effect of ischemic preconditioning in skeletal muscle measured by functional magnetic resonance imaging and spectroscopy: a randomized crossover trial

    Directory of Open Access Journals (Sweden)

    Bartko Johann

    2011-06-01

    Full Text Available Abstract Background Nuclear magnetic resonance (NMR imaging and spectroscopy have been applied to assess skeletal muscle oxidative metabolism. Therefore, in-vivo NMR may enable the characterization of ischemia-reperfusion injury. The goal of this study was to evaluate whether NMR could detect the effects of ischemic preconditioning (IPC in healthy subjects. Methods Twenty-three participants were included in two randomized crossover protocols in which the effects of IPC were measured by NMR and muscle force assessments. Leg ischemia was administered for 20 minutes with or without a subsequent impaired reperfusion for 5 minutes (stenosis model. IPC was administered 4 or 48 hours prior to ischemia. Changes in 31phosphate NMR spectroscopy and blood oxygen level-dependent (BOLD signals were recorded. 3-Tesla NMR data were compared to those obtained for isometric muscular strength. Results The phosphocreatine (PCr signal decreased robustly during ischemia and recovered rapidly during reperfusion. In contrast to PCr, the recovery of muscular strength was slow. During post-ischemic stenosis, PCr increased only slightly. The BOLD signal intensity decreased during ischemia, ischemic exercise and post-ischemic stenosis but increased during hyperemic reperfusion. IPC 4 hours prior to ischemia significantly increased the maximal PCr reperfusion signal and mitigated the peak BOLD signal during reperfusion. Conclusions Ischemic preconditioning positively influenced muscle metabolism during reperfusion; this resulted in an increase in PCr production and higher oxygen consumption, thereby mitigating the peak BOLD signal. In addition, an impairment of energy replenishment during the low-flow reperfusion was detected in this model. Thus, functional NMR is capable of characterizing changes in reperfusion and in therapeutic interventions in vivo. Trial Registration ClinicalTrials.gov: NCT00883467

  15. Muscles and their myokines

    DEFF Research Database (Denmark)

    Pedersen, Bente Klarlund

    2011-01-01

    In the past, the role of physical activity as a life-style modulating factor has been considered as that of a tool to balance energy intake. Although it is important to avoid obesity, physical inactivity should be discussed in a much broader context. There is accumulating epidemiological evidence...... or endocrine effects should be classified as 'myokines'. Given that skeletal muscle is the largest organ in the human body, our discovery that contracting skeletal muscle secretes proteins sets a novel paradigm: skeletal muscle is an endocrine organ producing and releasing myokines, which work in a hormone......-like fashion, exerting specific endocrine effects on other organs. Other myokines work via paracrine mechanisms, exerting local effects on signalling pathways involved in muscle metabolism. It has been suggested that myokines may contribute to exercise-induced protection against several chronic diseases....

  16. Pneumatic Muscle Actuator Control

    National Research Council Canada - National Science Library

    Lilly, John

    2000-01-01

    This research is relevant to the Air Fore mission because pneumatic muscle actuation devices arc advantageous for certain types of robotics as well as for strength and/or mobility assistance for humans...

  17. Brain–muscle interface

    Indian Academy of Sciences (India)

    2011-05-16

    May 16, 2011 ... Clipboard: Brain–muscle interface: The next-generation BMI. Radhika Rajan Neeraj Jain ... Keywords. Assistive devices; brain–machine interface; motor cortex; paralysis; spinal cord injury ... Journal of Biosciences | News ...

  18. Muscle glycogenolysis during exercise

    DEFF Research Database (Denmark)

    Richter, Erik; Ruderman, N B; Gavras, H

    1982-01-01

    glycogenolysis during exercise: contractions principally stimulate glycogenolysis early in exercise, and a direct effect of epinephrine on muscle is needed for continued glycogenolysis. In addition, epinephrine increased oxygen consumption and glucose uptake in both resting and electrically stimulated...

  19. Water and Muscle Contraction

    Directory of Open Access Journals (Sweden)

    Enrico Grazi

    2008-08-01

    Full Text Available The interaction between water and the protein of the contractile machinery as well as the tendency of these proteins to form geometrically ordered structures provide a link between water and muscle contraction. Protein osmotic pressure is strictly related to the chemical potential of the contractile proteins, to the stiffness of muscle structures and to the viscosity of the sliding of the thin over the thick filaments. Muscle power output and the steady rate of contraction are linked by modulating a single parameter, a viscosity coefficient. Muscle operation is characterized by working strokes of much shorter length and much quicker than in the classical model. As a consequence the force delivered and the stiffness attained by attached cross-bridges is much larger than usually believed.

  20. Muscle function loss

    Science.gov (United States)

    ... or head are damaged, you may have difficulty chewing and swallowing or closing your eyes. In these ... Medical Professional Muscle paralysis always requires immediate medical attention. If you notice gradual weakening or problems with ...

  1. Skeletal muscle intracellular pH and levels of high energy phosphates during hypercapnia in intact lizards by 31P NMR

    International Nuclear Information System (INIS)

    Johnson, D.C.; Hitzig, B.M.; Elmden, K.; McFarland, E.; Koutcher, J.; Kazemi, H.

    1986-01-01

    Lizards have been shown to reduce ventilation during CO 2 breathing. This is thought to be detrimental to the maintenance of intracellular pH (pHi) and levels of high energy phosphates. The authors subjected chameleons (n=4) to 5% CO 2 breathing and made serial measurements of tail (skeletal) muscle pHi, levels of phosphocreatine (PCr), and ATP utilizing high resolution 31 P NMR. pHi was unchanged from controls (7.27 +/- 0.06 units) (mean +/- SE) during 30 minutes of hypercapnia (7.19 +/- 0.09 units) (p>.2) demonstrating effective regulation of skeletal muscle pHi; however, there were significant decreases in the PCr/ATP ratios to 65% +/- 5% (p 2 availability because there were no increases in the levels of glycolytic intermediates and inorganic phosphate which would indicate tissue hypoxia. It is possible that an active process requiring ATP is required for the maintenance of pHi in the presence of hypercapnia and that the reduction of PCr/ATP ratio is a reflection of an increased utilization of ATP

  2. Kinetic energy absorbing pad

    International Nuclear Information System (INIS)

    Bricmont, R.J.; Hamilton, P.A.; Ming Long Ting, R.

    1981-01-01

    Reactors, fuel processing plants etc incorporate pipes and conduits for fluids under high pressure. Fractures, particularly adjacent to conduit elbows, produce a jet of liquid which whips the broken conduit at an extremely high velocity. An enormous impact load would be applied to any stationary object in the conduit's path. The design of cellular, corrugated metal impact pads to absorb the kinetic energy of the high velocity conduits is given. (U.K.)

  3. Differences between kinematic synergies and muscle synergies during two-digit grasping

    Directory of Open Access Journals (Sweden)

    Michele eTagliabue

    2015-03-01

    Full Text Available The large number of mechanical degrees of freedom of the hand is not fully exploited during actual movements such as grasping. Usually, angular movements in various joints tend to be coupled, and EMG activities in different hand muscles tend to be correlated. The occurrence of covariation in the former was termed kinematic synergies, in the latter muscle synergies. This study addresses two questions: (i Whether kinematic and muscle synergies can simultaneously accommodate for kinematic and kinetic constraints. (ii If so, whether there is an interrelation between kinematic and muscle synergies. We used a reach-grasp-and-pull paradigm and recorded the hand kinematics as well as 8 surface EMGs. Subjects had to either perform a precision grip or side grip and had to modify their grip force in order to displace an object against a low or high load. The analysis was subdivided into three epochs: reach, grasp-and-pull, and static hold. Principal component analysis (PCA, temporal or static was performed separately for all three epochs, in the kinematic and in the EMG domain. PCA revealed that (i Kinematic- and muscle-synergies can simultaneously accommodate kinematic (grip type and kinetic task constraints (load condition. (ii Upcoming grip and load conditions of the grasp are represented in kinematic- and muscle-synergies already during reach. Phase plane plots of the principal muscle-synergy against the principal kinematic synergy revealed (iii that the muscle-synergy is linked (correlated, and in phase advance to the kinematic synergy during reach and during grasp-and-pull. Furthermore (iv, pair-wise correlations of EMGs during hold suggest that muscle-synergies are (in part implemented by coactivation of muscles through common input. Together, these results suggest that kinematic synergies have (at least in part their origin not just in muscular activation, but in synergiestic muscle activation. In short: kinematic synergies may result from muscle

  4. Human Leg Model Predicts Muscle Forces, States, and Energetics during Walking.

    Science.gov (United States)

    Markowitz, Jared; Herr, Hugh

    2016-05-01

    Humans employ a high degree of redundancy in joint actuation, with different combinations of muscle and tendon action providing the same net joint torque. Both the resolution of these redundancies and the energetics of such systems depend on the dynamic properties of muscles and tendons, particularly their force-length relations. Current walking models that use stock parameters when simulating muscle-tendon dynamics tend to significantly overestimate metabolic consumption, perhaps because they do not adequately consider the role of elasticity. As an alternative, we posit that the muscle-tendon morphology of the human leg has evolved to maximize the metabolic efficiency of walking at self-selected speed. We use a data-driven approach to evaluate this hypothesis, utilizing kinematic, kinetic, electromyographic (EMG), and metabolic data taken from five participants walking at self-selected speed. The kinematic and kinetic data are used to estimate muscle-tendon lengths, muscle moment arms, and joint moments while the EMG data are used to estimate muscle activations. For each subject we perform an optimization using prescribed skeletal kinematics, varying the parameters that govern the force-length curve of each tendon as well as the strength and optimal fiber length of each muscle while seeking to simultaneously minimize metabolic cost and maximize agreement with the estimated joint moments. We find that the metabolic cost of transport (MCOT) values of our participants may be correctly matched (on average 0.36±0.02 predicted, 0.35±0.02 measured) with acceptable joint torque fidelity through application of a single constraint to the muscle metabolic budget. The associated optimal muscle-tendon parameter sets allow us to estimate the forces and states of individual muscles, resolving redundancies in joint actuation and lending insight into the potential roles and control objectives of the muscles of the leg throughout the gait cycle.

  5. Human Leg Model Predicts Muscle Forces, States, and Energetics during Walking.

    Directory of Open Access Journals (Sweden)

    Jared Markowitz

    2016-05-01

    Full Text Available Humans employ a high degree of redundancy in joint actuation, with different combinations of muscle and tendon action providing the same net joint torque. Both the resolution of these redundancies and the energetics of such systems depend on the dynamic properties of muscles and tendons, particularly their force-length relations. Current walking models that use stock parameters when simulating muscle-tendon dynamics tend to significantly overestimate metabolic consumption, perhaps because they do not adequately consider the role of elasticity. As an alternative, we posit that the muscle-tendon morphology of the human leg has evolved to maximize the metabolic efficiency of walking at self-selected speed. We use a data-driven approach to evaluate this hypothesis, utilizing kinematic, kinetic, electromyographic (EMG, and metabolic data taken from five participants walking at self-selected speed. The kinematic and kinetic data are used to estimate muscle-tendon lengths, muscle moment arms, and joint moments while the EMG data are used to estimate muscle activations. For each subject we perform an optimization using prescribed skeletal kinematics, varying the parameters that govern the force-length curve of each tendon as well as the strength and optimal fiber length of each muscle while seeking to simultaneously minimize metabolic cost and maximize agreement with the estimated joint moments. We find that the metabolic cost of transport (MCOT values of our participants may be correctly matched (on average 0.36±0.02 predicted, 0.35±0.02 measured with acceptable joint torque fidelity through application of a single constraint to the muscle metabolic budget. The associated optimal muscle-tendon parameter sets allow us to estimate the forces and states of individual muscles, resolving redundancies in joint actuation and lending insight into the potential roles and control objectives of the muscles of the leg throughout the gait cycle.

  6. Calcite Dissolution Kinetics

    Science.gov (United States)

    Berelson, W.; Subhas, A.; Dong, S.; Naviaux, J.; Adkins, J. F.

    2016-12-01

    A geological buffer for high atmospheric CO2 concentrations is neutralization via reaction with CaCO3. We have been studying the dissolution kinetics of carbonate minerals using labeled 13C calcite and Picarro-based measurements of 13C enrichments in solution DIC. This methodology has greatly facilitated our investigation of dissolution kinetics as a function of water carbonate chemistry, temperature and pressure. One can adjust the saturation state Omega by changing the ion activity product (e.g. adjusting carbonate ion concentration), or by changing the solubility product (e.g. adjusting temperature or pressure). The canonical formulation of dissolution rate vs. omega has been refined (Subhas et al. 2015) and shows distinct non-linear behavior near equilibrium and rates in sea water of 1-3 e-6 g/cm2day at omega = 0.8. Carbonic anhydrase (CA), an enzyme that catalyzes the hydration of dissolved CO2 to carbonic acid, was shown (in concentrations 500x. This result points to the importance of carbonic acid in enhancing dissolution at low degrees of undersaturation. CA activity and abundance in nature must be considered regarding the role it plays in catalyzing dissolution. We also have been investigating the role of temperature on dissolution kinetics. An increase of 16C yields an order of magnitude increase in dissolution rate. Temperature (and P) also change Omega critical, the saturation state where dissolution rates change substantially. Increasing pressure (achieved in a pressure reaction chamber we built) also shifts Omega critical closer to equilibrium and small pressure increases have large impact on dissolution kinetics. Dissolution rates are enhanced by an order of magnitude for a change in pressure of 1500 psi relative to the dissolution rate achieved by water chemistry effects alone for an omega of 0.8. We've shown that the thermodynamic determination of saturation state does not adequately describe the kinetics of dissolution. The interplay of mineral

  7. Traditional versus functional strength training: Effects on muscle strength and power in the elderly

    OpenAIRE

    Seiler, Hilde Lohne; Torstveit, Monica Klungland; Anderssen, Sigmund A.

    2013-01-01

    Published versiom of an article in the journal:Journal of Aging and Physical Activity. Also available from Human Kinetics: http://http://journals.humankinetics.com/japa-back-issues/japa-volume-21-issue-1-january/traditional-versus-functional-strength-training-effects-on-muscle-strength-and-power-in-the-elderly The aim was to determine whether strength training with machines vs. functional strength training at 80% of one-repetition maximum improves muscle strength and power among the elderl...

  8. Comparative Statistical Mechanics of Muscle and Non-Muscle Contractile Systems: Stationary States of Near-Equilibrium Systems in A Linear Regime

    Directory of Open Access Journals (Sweden)

    Yves Lecarpentier

    2017-10-01

    Full Text Available A. Huxley’s equations were used to determine the mechanical properties of muscle myosin II (MII at the molecular level, as well as the probability of the occurrence of the different stages in the actin–myosin cycle. It was then possible to use the formalism of statistical mechanics with the grand canonical ensemble to calculate numerous thermodynamic parameters such as entropy, internal energy, affinity, thermodynamic flow, thermodynamic force, and entropy production rate. This allows us to compare the thermodynamic parameters of a non-muscle contractile system, such as the normal human placenta, with those of different striated skeletal muscles (soleus and extensor digitalis longus as well as the heart muscle and smooth muscles (trachea and uterus in the rat. In the human placental tissues, it was observed that the kinetics of the actin–myosin crossbridges were considerably slow compared with those of smooth and striated muscular systems. The entropy production rate was also particularly low in the human placental tissues, as compared with that observed in smooth and striated muscular systems. This is partly due to the low thermodynamic flow found in the human placental tissues. However, the unitary force of non-muscle myosin (NMII generated by each crossbridge cycle in the myofibroblasts of the human placental tissues was similar in magnitude to that of MII in the myocytes of both smooth and striated muscle cells. Statistical mechanics represents a powerful tool for studying the thermodynamics of all contractile muscle and non-muscle systems.

  9. Kinetic variation of protein metabolism in pregnant rats

    International Nuclear Information System (INIS)

    Kubo, Katsuharu

    1980-01-01

    Kinetic variation of nitrogen metabolism in the skeletal muscle and liver of rats during the course of pregnancy was studied by the use of 15 N-amino nitrogen during acclimatization on a protein-free diet. 15 N from 15 N-glycine given on day 1 of pregnancy decreased from the 1st to 2nd trimester in the liver, suggesting contribution to the N metabolic pool. In the muscle, the rate of 15 N showed a marked decrease in the 2nd trimester, indicating, along with an increased accumulation of the total muscular N content, N accumulation in muscle protein in the 2nd trimester and promoted decomposition of mobiler muscular protein in the 2nd trimester. The marked decrease in the muscle 15 N content from the 2nd trimester and the decrease in the total N content in the 3rd trimester support the serious involvement of muscular N in fetal growth. The level of 15 N from 15 N-ammonium during the course of pregnancy was significantly high in the 2nd trimester and low in the 3rd. The 2nd trimester showed amino N accumulation in the muscle, and the 3rd, a decrease in N accumulation and amino N release. In regard to the kinetics of 15 N-lysine in the cell fraction, the muscular microsomes showed a high 15 N accumulation in the 2nd trimester and a voluminous release in the 3rd trimester. In contrast, the liver microsomes showed a linear decrease of 15 N up to 2nd trimester, followed by no change. (Chiba, N.)

  10. Suppression of skeletal muscle signal using a crusher coil: A human cardiac (31) p-MR spectroscopy study at 7 tesla.

    Science.gov (United States)

    Schaller, Benoit; Clarke, William T; Neubauer, Stefan; Robson, Matthew D; Rodgers, Christopher T

    2016-03-01

    The translation of sophisticated phosphorus MR spectroscopy ((31)P-MRS) protocols to 7 Tesla (T) is particularly challenged by the issue of radiofrequency (RF) heating. Legal limits on RF heating make it hard to reliably suppress signals from skeletal muscle that can contaminate human cardiac (31)P spectra at 7T. We introduce the first surface-spoiling crusher coil for human cardiac (31)P-MRS at 7T. A planar crusher coil design was optimized with simulations and its performance was validated in phantoms. Crusher gradient pulses (100 μs) were then applied during human cardiac (31)P-MRS at 7T. In a phantom, residual signals were 50 ± 10% with BISTRO (B1 -insensitive train to obliterate signal), and 34 ± 8% with the crusher coil. In vivo, residual signals in skeletal muscle were 49 ± 4% using BISTRO, and 24 ± 5% using the crusher coil. Meanwhile, in the interventricular septum, spectral quality and metabolite quantification did not differ significantly between BISTRO (phosphocreatine/adenosine triphosphate [PCr/ATP] = 2.1 ± 0.4) and the crusher coil (PCr/ATP = 1.8 ± 0.4). However, the specific absorption rate (SAR) decreased from 96 ± 1% of the limit (BISTRO) to 16 ± 1% (crusher coil). A crusher coil is an SAR-efficient alternative for selectively suppressing skeletal muscle during cardiac (31)P-MRS at 7T. A crusher coil allows the use of sequence modules that would have been SAR-prohibitive, without compromising skeletal muscle suppression. © 2015 The Authors. Magnetic Resonance in Medicine Published by Wiley Periodicals, Inc. on behalf of International Society of Medicine in Resonance.

  11. Suppression of skeletal muscle signal using a crusher coil: A human cardiac 31p‐MR spectroscopy study at 7 tesla

    Science.gov (United States)

    Clarke, William T.; Neubauer, Stefan; Robson, Matthew D.; Rodgers, Christopher T.

    2015-01-01

    Purpose The translation of sophisticated phosphorus MR spectroscopy (31P‐MRS) protocols to 7 Tesla (T) is particularly challenged by the issue of radiofrequency (RF) heating. Legal limits on RF heating make it hard to reliably suppress signals from skeletal muscle that can contaminate human cardiac 31P spectra at 7T. We introduce the first surface‐spoiling crusher coil for human cardiac 31P‐MRS at 7T. Methods A planar crusher coil design was optimized with simulations and its performance was validated in phantoms. Crusher gradient pulses (100 μs) were then applied during human cardiac 31P‐MRS at 7T. Results In a phantom, residual signals were 50 ± 10% with BISTRO (B1‐insensitive train to obliterate signal), and 34 ± 8% with the crusher coil. In vivo, residual signals in skeletal muscle were 49 ± 4% using BISTRO, and 24 ± 5% using the crusher coil. Meanwhile, in the interventricular septum, spectral quality and metabolite quantification did not differ significantly between BISTRO (phosphocreatine/adenosine triphosphate [PCr/ATP] = 2.1 ± 0.4) and the crusher coil (PCr/ATP = 1.8 ± 0.4). However, the specific absorption rate (SAR) decreased from 96 ± 1% of the limit (BISTRO) to 16 ± 1% (crusher coil). Conclusion A crusher coil is an SAR‐efficient alternative for selectively suppressing skeletal muscle during cardiac 31P‐MRS at 7T. A crusher coil allows the use of sequence modules that would have been SAR‐prohibitive, without compromising skeletal muscle suppression. Magn Reson Med 75:962–972, 2016. © 2015 The Authors. Magnetic Resonance in Medicine Published by Wiley Periodicals, Inc. on behalf of International Society of Medicine in Resonance. PMID:25924813

  12. Kinetics of tetrataenite disordering

    International Nuclear Information System (INIS)

    Dos Santos, E.; Gattacceca, J.; Rochette, P.; Fillion, G.; Scorzelli, R.B.

    2015-01-01

    Tetrataenite is a chemically ordered L1 0 -type Fe 50 Ni 50 alloy detected for the first time in 1977 by 57 Fe Mössbauer spectroscopy studies in iron meteorites. The thermal history of meteorites, in particular short thermal events like those associated to hypervelocity impacts, can be constrained by tracing the presence of tetrataenite or its disordering into taenite. The knowledge of the disordering kinetics of tetrataenite, that is associated with changes in its magnetic properties, is still very fragmentary so that the time–temperature history of these meteorites cannot be constrained in details. Furthermore, knowledge of disordering kinetics is important due to potential technological application of tetrataenite as a rare-earth free strong magnet. Thus, this work provides the first time–temperature data for disordering reaction of tetrataenite. We have shown that disordering is not an instantaneous process but is a kinetic limited reaction. It was shown that disordering may take place at any temperature above the order–disorder transition for L 10 superstructure phase (∼320 °C) when the appropriate time-scale is considered. This result means that the apparent Curie point for tetrataenite is not an absolute property in the sense that any estimate of this parameter should be referred to a given time-scale. - Highlights: • The first time–temperature data for tetrataenite disordering reaction is provided. • Previous works does not give a complete picture of tetrataenite disordering. • Apparent Curie temperature of tetrataenite should be referred to a time-scale. • Tetrataenite can be used as a probe to detect thermal/shock events recorded in meteorites

  13. Quantum kinetic Ising models

    International Nuclear Information System (INIS)

    Augusiak, R; Cucchietti, F M; Lewenstein, M; Haake, F

    2010-01-01

    In this paper, we introduce a quantum generalization of classical kinetic Ising models (KIM), described by a certain class of quantum many-body master equations. Similarly to KIMs with detailed balance that are equivalent to certain Hamiltonian systems, our models reduce to a set of Hamiltonian systems determining the dynamics of the elements of the many-body density matrix. The ground states of these Hamiltonians are well described by the matrix product, or pair entangled projected states. We discuss critical properties of such Hamiltonians, as well as entanglement properties of their low-energy states.

  14. Interleaved localized 1H/31P nuclear magnetic resonance spectroscopy of skeletal muscle

    International Nuclear Information System (INIS)

    Meyerspeer, M.

    2005-09-01

    Nuclear magnetic resonance (NMR) has been used as a spectroscopic method in physics and chemistry before it was developed to become a diagnostic imaging tool in medicine. When NMR spectroscopy is applied to human tissue, metabolism can be studied in normal physiological and pathological states in vivo. Metabolite concentrations and rates can be monitored dynamically and with localization of a defined region of interest. The 'window' which is opened for observation, i.e. which quantities are measured, depends on the nucleus used for RF excitation. Mechanisms of adenosine tri-phosphate (ATP) resynthesis, as a direct source of energy for muscle contraction, are phosphocreatine (PCr) splitting, glycolysis, beta-oxidation and, finally, oxidative phosphorylation. Whilst the dependency of these processes' fractional contribution to muscular energy supply on exercise type and duration is well known, quantitative models of the regulating mechanisms involved are still subject of current research. A large fraction of the established knowledge about metabolism is based on biochemical analysis of tissue acquired invasively (e.g. microdialysis and open-flow microperfusion) or representing averaged metabolic concentrations for the whole body (via serum metabolites or gas exchange analysis). Localized NMR spectroscopy, however, is capable of non-invasively acquiring time-resolved data from a defined volume of interest, in vivo. In contrast to the vast majority of MRS studies investigating metabolism, where spectra of a single nucleus (commonly 1 H, 31 P or 13 C) were acquired or several MR spectra with different nuclei were measured in separate experiments, this work opens an additional 'window' on muscle metabolism by interleaved localized acquisition of 1 H and 31 P NMR spectra from human calf muscle in vivo, during rest, exercise and recovery, in a single experiment. Using this technique, the time courses of the concentrations of phosphocreatine, inorganic phosphate (Pi), ATP

  15. A comparative study of charge movement in rat and frog skeletal muscle fibres.

    Science.gov (United States)

    Hollingworth, S; Marshall, M W

    1981-12-01

    1. The middle of the fibre voltage--clamp technique (Adrian & Marshall, 1977), modified where necessary for electrically short muscle fibres, has been used to measure non-linear charge movements in mammalian fast twitch (rat extensor digitorum longus), mammalian slow twitch (rat soleus) and frog (sartorius) muscles. 2. The maximum amount of charge moved in mammalian fast twitch muscle at 2 degrees C in hypertonic solution, was 3--5 times greater than in slow twitch muscle. The voltage distribution of fast twitch charge was 10--15 mV more positive when compared to slow twitch. 3. In both mammalian muscle types hypertonic Ringer solution negatively shifted the voltage distribution of charge some 6 mV. The steepness of charge moved around mechanical threshold was unaffected by hypertonicity. 4. The amount of charge in frog sartorius fibres at 2 degrees C in hypertonic solution was about half of that in rat fast twitch muscle; the voltage distribution of the frog charge was similar to rat soleus muscle. 5. Warming between 2 and 15 degrees C had no effect on either the amount of steady-state distribution of charge in mammalian or frog muscles. 6. At 2 degrees C, the kinetics of charge movement in fast and slow twitch mammalian muscles were similar and 2--3 times faster than frog muscle at the same temperature. In fast and slow mammalian fibres at 2 degrees C similar times were taken to shift the same fractions of the total amount of charge. The Q10 of charge movement kinetics was between 1.2 and 2.0 in the three muscles studied.

  16. in Skeletal Muscle

    Directory of Open Access Journals (Sweden)

    Espen E. Spangenburg

    2011-01-01

    Full Text Available Triglyceride storage is altered across various chronic health conditions necessitating various techniques to visualize and quantify lipid droplets (LDs. Here, we describe the utilization of the BODIPY (493/503 dye in skeletal muscle as a means to analyze LDs. We found that the dye was a convenient and simple approach to visualize LDs in both sectioned skeletal muscle and cultured adult single fibers. Furthermore, the dye was effective in both fixed and nonfixed cells, and the staining seemed unaffected by permeabilization. We believe that the use of the BODIPY (493/503 dye is an acceptable alternative and, under certain conditions, a simpler method for visualizing LDs stored within skeletal muscle.

  17. Hydraulically actuated artificial muscles

    Science.gov (United States)

    Meller, M. A.; Tiwari, R.; Wajcs, K. B.; Moses, C.; Reveles, I.; Garcia, E.

    2012-04-01

    Hydraulic Artificial Muscles (HAMs) consisting of a polymer tube constrained by a nylon mesh are presented in this paper. Despite the actuation mechanism being similar to its popular counterpart, which are pneumatically actuated (PAM), HAMs have not been studied in depth. HAMs offer the advantage of compliance, large force to weight ratio, low maintenance, and low cost over traditional hydraulic cylinders. Muscle characterization for isometric and isobaric tests are discussed and compared to PAMs. A model incorporating the effect of mesh angle and friction have also been developed. In addition, differential swelling of the muscle on actuation has also been included in the model. An application of lab fabricated HAMs for a meso-scale robotic system is also presented.

  18. Foot muscles strengthener

    Directory of Open Access Journals (Sweden)

    Boris T. Glavač

    2012-04-01

    Full Text Available Previous experience in the correction of flat feet consisted of the use of insoles for shoes and exercises with toys, balls, rollers, inclined planes, etc. A device for strengthening foot muscles is designed for the correction of flat feet in children and, as its name suggests, for strengthening foot muscles in adults. The device is made of wood and metal, with a mechanism and technical solutions, enabling the implementation of specific exercises to activate muscles responsible for the formation of the foot arch. It is suitable for home use with controlled load quantities since it has calibrated springs. The device is patented with the Intellectual Property Office, Republic of Serbia, as a petty patent.

  19. Kinetics of coal pyrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Seery, D.J.; Freihaut, J.D.; Proscia, W.M. (United Technologies Research Center, East Hartford, CT (USA)); Howard, J.B.; Peters, W.; Hsu, J.; Hajaligol, M.; Sarofim, A. (Massachusetts Inst. of Tech., Cambridge, MA (USA)); Jenkins, R.; Mallin, J.; Espindola-Merin, B. (Pennsylvania State Univ., University Park, PA (USA)); Essenhigh, R.; Misra, M.K. (Ohio State Univ., Columbus, OH (USA))

    1989-07-01

    This report contains results of a coordinated, multi-laboratory investigation of coal devolatilization. Data is reported pertaining to the devolatilization for bituminous coals over three orders of magnitude in apparent heating rate (100 to 100,000 + {degree}C/sec), over two orders of magnitude in particle size (20 to 700 microns), final particle temperatures from 400 to 1600{degree}C, heat transfer modes ranging from convection to radiative, ambient pressure ranging from near vacuum to one atmosphere pressure. The heat transfer characteristics of the reactors are reported in detail. It is assumed the experimental results are to form the basis of a devolatilization data base. Empirical rate expressions are developed for each phase of devolatilization which, when coupled to an awareness of the heat transfer rate potential of a particular devolatilization reactor, indicate the kinetics emphasized by a particular system reactor plus coal sample. The analysis indicates the particular phase of devolatilization that will be emphasized by a particular reactor type and, thereby, the kinetic expressions appropriate to that devolatilization system. Engineering rate expressions are developed from the empirical rate expressions in the context of a fundamental understanding of coal devolatilization developed in the course of the investigation. 164 refs., 223 figs., 44 tabs.

  20. Repair kinetics in tissues

    International Nuclear Information System (INIS)

    Thames, H.D.

    1989-01-01

    Monoexponential repair kinetics is based on the assumption of a single, dose-independent rate of repair of sublethal injury in the target cells for tissue injury after exposure to ionizing radiation. Descriptions of the available data based on this assumption have proved fairly successful for both acutely responding (skin, lip mucosa, gut) and late-responding (lung, spinal cord) normal tissues. There are indications of biphasic exponential repair in both categories, however. Unfortunately, the data usually lack sufficient resolution to permit unambiguous determination of the repair rates. There are also indications that repair kinetics may depend on the size of the dose. The data are conflicting on this account, however, with suggestions of both faster and slower repair after larger doses. Indeed, experiments that have been explicitly designed to test this hypothesis show either no effect (gut, spinal cord), faster repair after higher doses (lung, kidney), or slower repair after higher doses (skin). Monoexponential repair appears to be a fairly accurate description that provides an approximation to a more complicated picture, the elucidation of whose details will, however, require very careful and extensive experimental study. (author). 30 refs.; 1 fig

  1. Diffusion Influenced Adsorption Kinetics.

    Science.gov (United States)

    Miura, Toshiaki; Seki, Kazuhiko

    2015-08-27

    When the kinetics of adsorption is influenced by the diffusive flow of solutes, the solute concentration at the surface is influenced by the surface coverage of solutes, which is given by the Langmuir-Hinshelwood adsorption equation. The diffusion equation with the boundary condition given by the Langmuir-Hinshelwood adsorption equation leads to the nonlinear integro-differential equation for the surface coverage. In this paper, we solved the nonlinear integro-differential equation using the Grünwald-Letnikov formula developed to solve fractional kinetics. Guided by the numerical results, analytical expressions for the upper and lower bounds of the exact numerical results were obtained. The upper and lower bounds were close to the exact numerical results in the diffusion- and reaction-controlled limits, respectively. We examined the validity of the two simple analytical expressions obtained in the diffusion-controlled limit. The results were generalized to include the effect of dispersive diffusion. We also investigated the effect of molecular rearrangement of anisotropic molecules on surface coverage.

  2. Stoichio-Kinetic Modeling of Fenton Chemistry in a Meat-Mimetic Aqueous-Phase Medium.

    Science.gov (United States)

    Oueslati, Khaled; Promeyrat, Aurélie; Gatellier, Philippe; Daudin, Jean-Dominique; Kondjoyan, Alain

    2018-05-31

    Fenton reaction kinetics, which involved an Fe(II)/Fe(III) oxidative redox cycle, were studied in a liquid medium that mimics meat composition. Muscle antioxidants (enzymes, peptides, and vitamins) were added one by one in the medium to determine their respective effects on the formation of superoxide and hydroxyl radicals. A stoichio-kinetic mathematical model was used to predict the formation of these radicals under different iron and H 2 O 2 concentrations and temperature conditions. The difference between experimental and predicted results was mainly due to iron reactivity, which had to be taken into account in the model, and to uncertainties on some of the rate constant values introduced in the model. This stoichio-kinetic model will be useful to predict oxidation during meat processes, providing it can be completed to take into account the presence of myoglobin in the muscle.

  3. Chemical kinetics and reaction mechanism

    International Nuclear Information System (INIS)

    Jung, Ou Sik; Park, Youn Yeol

    1996-12-01

    This book is about chemical kinetics and reaction mechanism. It consists of eleven chapters, which deal with reaction and reaction speed on reaction mechanism, simple reaction by rate expression, reversible reaction and simultaneous reaction, successive reaction, complicated reaction mechanism, assumption for reaction mechanism, transition state theory, successive reaction and oscillating reaction, reaction by solution, research method high except kinetics on reaction mechanism, high reaction of kinetics like pulsed radiolysis.

  4. Chemical kinetics of gas reactions

    CERN Document Server

    Kondrat'Ev, V N

    2013-01-01

    Chemical Kinetics of Gas Reactions explores the advances in gas kinetics and thermal, photochemical, electrical discharge, and radiation chemical reactions. This book is composed of 10 chapters, and begins with the presentation of general kinetic rules for simple and complex chemical reactions. The next chapters deal with the experimental methods for evaluating chemical reaction mechanisms and some theories of elementary chemical processes. These topics are followed by discussions on certain class of chemical reactions, including unimolecular, bimolecular, and termolecular reactions. The rema

  5. Rectus abdominis muscle endometriosis

    International Nuclear Information System (INIS)

    Goker, A.

    2014-01-01

    Endometriosis is characterized by an abnormal existence of functional endometrial tissue outside the uterine cavity, typically occuring within the pelvis of women in reproductive age. We report two cases with endometriosis of the abdominal wall; the first one in the rectus abdominis muscle and the second one in the surgical scar of previous caesarean incision along with the rectus abdominis muscle. Pre-operative evaluation included magnetic resonance imaging. The masses were dissected free from the surrounding tissue and excised with clear margins. Diagnosis of the excised lesions were verified by histopathology. (author)

  6. Skeletal muscle connective tissue

    DEFF Research Database (Denmark)

    Brüggemann, Dagmar Adeline

    in the structure of fibrous collagen and myofibers at high-resolution. The results demonstrate that the collagen composition in the extra cellular matrix of Gadus morhua fish muscle is much more complex than previously anticipated, as it contains type III, IV, V  and VI collagen in addition to type I. The vascular....... Consequently, functional structures, ensuring "tissue maintenance" must form a major role of connective tissue, in addition that is to the force transmitting structures one typically finds in muscle. Vascular structures have also been shown to change their mechanical properties with age and it has been shown...

  7. Adsorption analysis equilibria and kinetics

    CERN Document Server

    Do, Duong D

    1998-01-01

    This book covers topics of equilibria and kinetics of adsorption in porous media. Fundamental equilibria and kinetics are dealt with for homogeneous as well as heterogeneous particles. Five chapters of the book deal with equilibria and eight chapters deal with kinetics. Single component as well as multicomponent systems are discussed. In kinetics analysis, we deal with the various mass transport processes and their interactions inside a porous particle. Conventional approaches as well as the new approach using Maxwell-Stefan equations are presented. Various methods to measure diffusivity, such

  8. Muscle force depends on the amount of transversal muscle loading.

    Science.gov (United States)

    Siebert, Tobias; Till, Olaf; Stutzig, Norman; Günther, Michael; Blickhan, Reinhard

    2014-06-03

    Skeletal muscles are embedded in an environment of other muscles, connective tissue, and bones, which may transfer transversal forces to the muscle tissue, thereby compressing it. In a recent study we demonstrated that transversal loading of a muscle with 1.3Ncm(-2) reduces maximum isometric force (Fim) and rate of force development by approximately 5% and 25%, respectively. The aim of the present study was to examine the influence of increasing transversal muscle loading on contraction dynamics. Therefore, we performed isometric experiments on rat M. gastrocnemius medialis (n=9) without and with five different transversal loads corresponding to increasing pressures of 1.3Ncm(-2) to 5.3Ncm(-2) at the contact area between muscle and load. Muscle loading was induced by a custom-made plunger which was able to move in transversal direction. Increasing transversal muscle loading resulted in an almost linear decrease in muscle force from 4.8±1.8% to 12.8±2% Fim. Compared to an unloaded isometric contraction, rate of force development decreased from 20.2±4.0% at 1.3Ncm(-2) muscle loading to 34.6±5.7% at 5.3Ncm(-2). Experimental observation of the impact of transversal muscle loading on contraction dynamics may help to better understand muscle tissue properties. Moreover, applying transversal loads to muscles opens a window to analyze three-dimensional muscle force generation. Data presented in this study may be important to develop and validate muscle models which enable simulation of muscle contractions under compression and enlighten the mechanisms behind. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. Effects of oblique muscle surgery on the rectus muscle pulley

    International Nuclear Information System (INIS)

    Okanobu, Hirotaka; Kono, Reika; Ohtsuki, Hiroshi

    2011-01-01

    The purpose of this study was to determine the position of rectus muscle pulleys in Japanese eyes and to evaluate the effect of oblique muscle surgery on rectus muscle pulleys. Quasi-coronal plane MRI was used to determine area centroids of the 4 rectus muscles. The area centroids of the rectus muscles were transformed to 2-dimensional coordinates to represent pulley positions. The effects of oblique muscle surgery on the rectus muscle pulley positions in the coronal plane were evaluated in 10 subjects with cyclovertical strabismus and, as a control, pulley locations in 7 normal Japanese subjects were calculated. The mean positions of the rectus muscle pulleys in the coronal plane did not significantly differ from previous reports on normal populations, including Caucasians. There were significant positional shifts of the individual horizontal and vertical rectus muscle pulleys in 3 (100%) patients with inferior oblique advancement, but not in eyes with inferior oblique recession and superior oblique tendon advancement surgery. The surgical cyclorotatory effect was significantly correlated with the change in the angle of inclination formed by the line connecting the vertical rectus muscles (p=0.0234), but weakly correlated with that of the horizontal rectus muscles. The most important factor that affects the pulley position is the amount of ocular torsion, not the difference in surgical procedure induced by oblique muscle surgery. (author)

  10. Composition of Muscle Fiber Types in Rat Rotator Cuff Muscles.

    Science.gov (United States)

    Rui, Yongjun; Pan, Feng; Mi, Jingyi

    2016-10-01

    The rat is a suitable model to study human rotator cuff pathology owing to the similarities in morphological anatomy structure. However, few studies have reported the composition muscle fiber types of rotator cuff muscles in the rat. In this study, the myosin heavy chain (MyHC) isoforms were stained by immunofluorescence to show the muscle fiber types composition and distribution in rotator cuff muscles of the rat. It was found that rotator cuff muscles in the rat were of mixed fiber type composition. The majority of rotator cuff fibers labeled positively for MyHCII. Moreover, the rat rotator cuff muscles contained hybrid fibers. So, compared with human rotator cuff muscles composed partly of slow-twitch fibers, the majority of fast-twitch fibers in rat rotator cuff muscles should be considered when the rat model study focus on the pathological process of rotator cuff muscles after injury. Gaining greater insight into muscle fiber types in rotator cuff muscles of the rat may contribute to elucidate the mechanism of pathological change in rotator cuff muscles-related diseases. Anat Rec, 299:1397-1401, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  11. Mitochondrial affinity for ADP is twofold lower in creatine kinase knock-out muscles - Possible role in rescuing cellular energy homeostasis

    NARCIS (Netherlands)

    ter Veld, F; Jeneson, JAL; Nicolay, K

    Adaptations of the kinetic properties of mitochondria in striated muscle lacking cytosolic (M) and/or mitochondrial (Mi) creatine kinase (CK) isoforms in comparison to wild-type (WT) were investigated in vitro. Intact mitochondria were isolated from heart and gastrocnemius muscle of WT and single-

  12. Nondestructive Estimation of Muscle Contributions to STS Training with Different Loadings Based on Wearable Sensor System.

    Science.gov (United States)

    Liu, Kun; Liu, Yong; Yan, Jianchao; Sun, Zhenyuan

    2018-03-25

    Partial body weight support or loading sit-to-stand (STS) rehabilitation can be useful for persons with lower limb dysfunction to achieve movement again based on the internal residual muscle force and external assistance. To explicate how the muscles contribute to the kinetics and kinematics of STS performance by non-invasive in vitro detection and to nondestructively estimate the muscle contributions to STS training with different loadings, a wearable sensor system was developed with ground reaction force (GRF) platforms, motion capture inertial sensors and electromyography (EMG) sensors. To estimate the internal moments of hip, knee and ankle joints and quantify the contributions of individual muscle and gravity to STS movement, the inverse dynamics analysis on a simplified STS biomechanical model with external loading is proposed. The functional roles of the lower limb individual muscles (rectus femoris (RF), gluteus maximus (GM), vastus lateralis (VL), tibialis anterior (TA) and gastrocnemius (GAST)) during STS motion and the mechanism of the muscles' synergies to perform STS-specific subtasks were analyzed. The muscle contributions to the biomechanical STS subtasks of vertical propulsion, anteroposterior (AP) braking and propulsion for body balance in the sagittal plane were quantified by experimental studies with EMG, kinematic and kinetic data.

  13. Force encoding in muscle spindles during stretch of passive muscle.

    Directory of Open Access Journals (Sweden)

    Kyle P Blum

    2017-09-01

    Full Text Available Muscle spindle proprioceptive receptors play a primary role in encoding the effects of external mechanical perturbations to the body. During externally-imposed stretches of passive, i.e. electrically-quiescent, muscles, the instantaneous firing rates (IFRs of muscle spindles are associated with characteristics of stretch such as length and velocity. However, even in passive muscle, there are history-dependent transients of muscle spindle firing that are not uniquely related to muscle length and velocity, nor reproduced by current muscle spindle models. These include acceleration-dependent initial bursts, increased dynamic response to stretch velocity if a muscle has been isometric, and rate relaxation, i.e., a decrease in tonic IFR when a muscle is held at a constant length after being stretched. We collected muscle spindle spike trains across a variety of muscle stretch kinematic conditions, including systematic changes in peak length, velocity, and acceleration. We demonstrate that muscle spindle primary afferents in passive muscle fire in direct relationship to muscle force-related variables, rather than length-related variables. Linear combinations of whole muscle-tendon force and the first time derivative of force (dF/dt predict the entire time course of transient IFRs in muscle spindle Ia afferents during stretch (i.e., lengthening of passive muscle, including the initial burst, the dynamic response to lengthening, and rate relaxation following lengthening. Similar to acceleration scaling found previously in postural responses to perturbations, initial burst amplitude scaled equally well to initial stretch acceleration or dF/dt, though later transients were only described by dF/dt. The transient increase in dF/dt at the onset of lengthening reflects muscle short-range stiffness due to cross-bridge dynamics. Our work demonstrates a critical role of muscle cross-bridge dynamics in history-dependent muscle spindle IFRs in passive muscle

  14. Force encoding in muscle spindles during stretch of passive muscle.

    Science.gov (United States)

    Blum, Kyle P; Lamotte D'Incamps, Boris; Zytnicki, Daniel; Ting, Lena H

    2017-09-01

    Muscle spindle proprioceptive receptors play a primary role in encoding the effects of external mechanical perturbations to the body. During externally-imposed stretches of passive, i.e. electrically-quiescent, muscles, the instantaneous firing rates (IFRs) of muscle spindles are associated with characteristics of stretch such as length and velocity. However, even in passive muscle, there are history-dependent transients of muscle spindle firing that are not uniquely related to muscle length and velocity, nor reproduced by current muscle spindle models. These include acceleration-dependent initial bursts, increased dynamic response to stretch velocity if a muscle has been isometric, and rate relaxation, i.e., a decrease in tonic IFR when a muscle is held at a constant length after being stretched. We collected muscle spindle spike trains across a variety of muscle stretch kinematic conditions, including systematic changes in peak length, velocity, and acceleration. We demonstrate that muscle spindle primary afferents in passive muscle fire in direct relationship to muscle force-related variables, rather than length-related variables. Linear combinations of whole muscle-tendon force and the first time derivative of force (dF/dt) predict the entire time course of transient IFRs in muscle spindle Ia afferents during stretch (i.e., lengthening) of passive muscle, including the initial burst, the dynamic response to lengthening, and rate relaxation following lengthening. Similar to acceleration scaling found previously in postural responses to perturbations, initial burst amplitude scaled equally well to initial stretch acceleration or dF/dt, though later transients were only described by dF/dt. The transient increase in dF/dt at the onset of lengthening reflects muscle short-range stiffness due to cross-bridge dynamics. Our work demonstrates a critical role of muscle cross-bridge dynamics in history-dependent muscle spindle IFRs in passive muscle lengthening conditions

  15. MRI appearance of muscle denervation

    Energy Technology Data Exchange (ETDEWEB)

    Kamath, S. [University Hospital of Wales, Department of Radiology, Cardiff (United Kingdom); Venkatanarasimha, N.; Walsh, M.A.; Hughes, P.M. [Derriford Hospital, Department of Radiology, Plymouth (United Kingdom)

    2008-05-15

    Muscle denervation results from a variety of causes including trauma, neoplasia, neuropathies, infections, autoimmune processes and vasculitis. Traditionally, the diagnosis of muscle denervation was based on clinical examination and electromyography. Magnetic resonance imaging (MRI) offers a distinct advantage over electromyography, not only in diagnosing muscle denervation, but also in determining its aetiology. MRI demonstrates characteristic signal intensity patterns depending on the stage of muscle denervation. The acute and subacutely denervated muscle shows a high signal intensity pattern on fluid sensitive sequences and normal signal intensity on T1-weighted MRI images. In chronic denervation, muscle atrophy and fatty infiltration demonstrate high signal changes on T1-weighted sequences in association with volume loss. The purpose of this review is to summarise the MRI appearance of denervated muscle, with special emphasis on the signal intensity patterns in acute and subacute muscle denervation. (orig.)

  16. Anti-smooth muscle antibody

    Science.gov (United States)

    ... gov/ency/article/003531.htm Anti-smooth muscle antibody To use the sharing features on this page, please enable JavaScript. Anti-smooth muscle antibody is a blood test that detects the presence ...

  17. Human skeletal muscle fatty acid and glycerol metabolism during rest, exercise and recovery

    DEFF Research Database (Denmark)

    Van Hall, Gerrit; Sacchetti, M; Rådegran, G

    2002-01-01

    glycerol uptake was observed, which was substantially higher during exercise. Total body skeletal muscle FA and glycerol uptake/release was estimated to account for 18-25 % of whole body R(d) or R(a). In conclusion: (1) skeletal muscle FA and glycerol metabolism, using the leg arterial-venous difference......This study was conducted to investigate skeletal muscle fatty acid (FA) and glycerol kinetics and to determine the contribution of skeletal muscle to whole body FA and glycerol turnover during rest, 2 h of one-leg knee-extensor exercise at 65 % of maximal leg power output, and 3 h of recovery....... To this aim, the leg femoral arterial-venous difference technique was used in combination with a continuous infusion of [U-(13)C]palmitate and [(2)H(5)]glycerol in five post-absorptive healthy volunteers (22 +/- 3 years). The influence of contamination from non-skeletal muscle tissues, skin and subcutaneous...

  18. Noninvasive detection of change in skeletal muscle oxygenation during incremental exercise with near-infrared spectroscopy

    Science.gov (United States)

    Liu, Fang; Luo, Qingming; Xu, Guodong; Li, Pengcheng

    2003-12-01

    Near infrared spectroscopy (NIRS) has been developed as a non-invasive method to assess O2 delivery, O2 consumption and blood flow, in diverse local muscle groups at rest and during exercise. The aim of this study was to investigate local O2 consumption in exercising muscle by use of near-infrared spectroscopy (NIRS). Ten elite athletes of different sport items were tested in rest and during step incremental load exercise. Local variations of quadriceps muscles were investigated with our wireless NIRS blood oxygen monitor system. The results show that the changes of blood oxygen relate on the sport items, type of muscle, kinetic capacity et al. These results indicate that NIRS is a potential useful tool to detect local muscle oxygenation and blood flow profiles; therefore it might be easily applied for evaluating the effect of athletes training.

  19. Lipolysis in Skeletal Muscle

    DEFF Research Database (Denmark)

    Serup, Annette Karen Lundbeck

    chemical structure of DAG. We took advantage of the fact that insulin sensitivity is increased after exercise, and that mice knocked out (KO) of HSL accumulate DAG after exercise, and measured insulin stimulated glucose uptake after treadmill running in skeletal muscle from HSL KO mice and wildtype control...

  20. Metabolic Diseases of Muscle

    Science.gov (United States)

    ... here and still get the great care and treatment I received in Michigan.” MDA Is Here to Help You T he Muscular Dystrophy Association offers a vast array of services to help you and your family deal with metabolic diseases of muscle. The staff at your local MDA office is ...

  1. Increased lower limb muscle coactivation reduces gait performance and increases metabolic cost in patients with hereditary spastic paraparesis.

    Science.gov (United States)

    Rinaldi, Martina; Ranavolo, Alberto; Conforto, Silvia; Martino, Giovanni; Draicchio, Francesco; Conte, Carmela; Varrecchia, Tiwana; Bini, Fabiano; Casali, Carlo; Pierelli, Francesco; Serrao, Mariano

    2017-10-01

    The aim of this study was to investigate the lower limb muscle coactivation and its relationship with muscles spasticity, gait performance, and metabolic cost in patients with hereditary spastic paraparesis. Kinematic, kinetic, electromyographic and energetic parameters of 23 patients and 23 controls were evaluated by computerized gait analysis system. We computed ankle and knee antagonist muscle coactivation indexes throughout the gait cycle and during the subphases of gait. Energy consumption and energy recovery were measured as well. In addition to the correlation analysis between coactivation indexes and clinical variables, correlations between coactivation indexes and time-distance, kinematic, kinetic, and energetic parameters were estimated. Increased coactivity indexes of both knee and ankle muscles throughout the gait cycle and during the subphases of gait were observed in patients compared with controls. Energetic parameters were significantly higher in patients than in controls. Both knee and ankle muscle coactivation indexes were positively correlated with knee and ankle spasticity (Ashworth score), respectively. Knee and ankle muscle coactivation indexes were both positively correlated with energy consumption and both negatively correlated with energy recovery. Positive correlations between the Ashworth score and lower limb muscle coactivation suggest that abnormal lower limb muscle coactivation in patients with hereditary spastic paraparesis reflects a primary deficit linked to lower limb spasticity. Furthermore, these abnormalities influence the energetic mechanisms during walking. Identifying excessive muscle coactivation may be helpful in individuating the rehabilitative treatments and designing specific orthosis to restrain spasticity. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Kinetics of Social Contagion

    Science.gov (United States)

    Ruan, Zhongyuan; Iñiguez, Gerardo; Karsai, Márton; Kertész, János

    2015-11-01

    Diffusion of information, behavioral patterns or innovations follows diverse pathways depending on a number of conditions, including the structure of the underlying social network, the sensitivity to peer pressure and the influence of media. Here we study analytically and by simulations a general model that incorporates threshold mechanism capturing sensitivity to peer pressure, the effect of "immune" nodes who never adopt, and a perpetual flow of external information. While any constant, nonzero rate of dynamically introduced spontaneous adopters leads to global spreading, the kinetics by which the asymptotic state is approached shows rich behavior. In particular, we find that, as a function of the immune node density, there is a transition from fast to slow spreading governed by entirely different mechanisms. This transition happens below the percolation threshold of network fragmentation, and has its origin in the competition between cascading behavior induced by adopters and blocking due to immune nodes. This change is accompanied by a percolation transition of the induced clusters.

  3. The temperature hydration kinetics

    Directory of Open Access Journals (Sweden)

    Mircea Oroian

    2017-07-01

    Full Text Available The aim of this study is to evaluate the hydration kinetics of lentil seeds (Lens culinaris in water at different temperatures (25, 32.5, 40, 55, 70 and 80 °C for assessing the adequacy of models for describing the absorption phenomena during soaking. The diffusion coefficient values were calculated using Fick’s model for spherical and hemispherical geometries and the values were in the range of 10−6 m2/s. The experimental data were fitted to Peleg, Sigmoidal, Weibull and Exponential models. The models adequacy was determined using regression coefficients (R2, root mean square error (RMSE and reduced chi-square (χ2. The Peleg model is the suitable one for predicting the experimental data. Temperature had a positive and significant effect on the water absorption capacities and absorption was an endothermic process.

  4. Skeletal muscle bioenergetics during all-out exercise: mechanistic insight into the oxygen uptake slow component and neuromuscular fatigue.

    Science.gov (United States)

    Broxterman, Ryan M; Layec, Gwenael; Hureau, Thomas J; Amann, Markus; Richardson, Russell S

    2017-05-01

    Although all-out exercise protocols are commonly used, the physiological mechanisms underlying all-out exercise performance are still unclear, and an in-depth assessment of skeletal muscle bioenergetics is lacking. Therefore, phosphorus magnetic resonance spectroscopy ( 31 P-MRS) was utilized to assess skeletal muscle bioenergetics during a 5-min all-out intermittent isometric knee-extensor protocol in eight healthy men. Metabolic perturbation, adenosine triphosphate (ATP) synthesis rates, ATP cost of contraction, and mitochondrial capacity were determined from intramuscular concentrations of phosphocreatine (PCr), inorganic phosphate (P i ), diprotonated phosphate ([Formula: see text]), and pH. Peripheral fatigue was determined by exercise-induced alterations in potentiated quadriceps twitch force (Q tw ) evoked by supramaximal electrical femoral nerve stimulation. The oxidative ATP synthesis rate (ATP OX ) attained and then maintained peak values throughout the protocol, despite an ~63% decrease in quadriceps maximal force production. ThusATP OX normalized to force production (ATP OX gain) significantly increased throughout the exercise (1st min: 0.02 ± 0.01, 5th min: 0.04 ± 0.01 mM·min -1 ·N -1 ), as did the ATP cost of contraction (1st min: 0.048 ± 0.019, 5th min: 0.052 ± 0.015 mM·min -1 ·N -1 ). Additionally, the pre- to postexercise change in Q tw (-52 ± 26%) was significantly correlated with the exercise-induced change in intramuscular pH ( r = 0.75) and [Formula: see text] concentration ( r = 0.77). In conclusion, the all-out exercise protocol utilized in the present study elicited a "slow component-like" increase in intramuscular ATP OX gain as well as a progressive increase in the phosphate cost of contraction. Furthermore, the development of peripheral fatigue was closely related to the perturbation of specific fatigue-inducing intramuscular factors (i.e., pH and [Formula: see text] concentration). NEW & NOTEWORTHY The physiological mechanisms

  5. Cellular assessment of muscle in COPD: case studies of two males

    Directory of Open Access Journals (Sweden)

    Howard J Green

    2009-11-01

    Full Text Available Howard J Green1, Eric Bombardier1, Margaret E Burnett1, Christine L D’Arsigny2, Sobia Iqbal1, Katherine A Webb2, Jing Ouyang1, Denis E O’Donnell21Department of Kinesiology, University of Waterloo, Waterloo, ON, Canada; 2Division of Respiratory and Critical Care Medicine, Department of Medicine, Queen’s University, Kingston, ON, CanadaAbstract: The objective of this paper is to provide an overview of the recent developments in muscle physiology and biochemistry in general, and with respect to chronic obstructive pulmonary disease (COPD specifically. As a way of illustration, we have presented data on the remodeling that occurs in vastus lateralis in two patients with COPD (COPD #1, forced expiratory volume in one second/forced vital capacity [FEV1/FVC] = 63%; COPD #2, FEV1/FVC = 41% exhibiting differences in muscle wasting as compared to healthy controls (CON;FEV1/FVC = 111 ± 2.2%, n = 4. Type I fibers percentages were lower in both COPD #1 (16.7 and COPD #2 (24.9 compared to CON (57.3 ± 5.2. Cross sectional area of the type I fibers of the patients ranged between 65%–68% of CON and for the type II subtypes (IIA, IIAX, IIX between 74% and 89% (COPD #1 and 17%–32% (COPD #2. A lower number of capillary contacts were observed for all fiber types in COPD #1 but not COPD #2. Lower concentrations of adenosine triphosphate (ATP (24%–26% and phosphocreatine (18%–20%, but not lactate occurred in COPD. In contrast to COPD #1, who displayed normal glucose transporter content, GLUT1 and GLUT4 were only 71% and 54%, respectively of CON in COPD #2. Lower monocarboxylate contents were found for MCT1 in both COPD #1 (63% and COPD #2 (41% and for MCT4 (78% in COPD #1. Maximal oxidative enzyme activities (Vmax for COPD #2 ranged between 37% (succinic dehydrogenase and 70% (cytochrome C oxidase of CON. For the cytosolic enzymes, Vmax ranged between 89% (hexokinase to 31% (pyruvate kinase of CON. Depressions were also observed in Vmax of the Na

  6. Time-Course of Muscle Mass Loss, Damage, and Proteolysis in Gastrocnemius following Unloading and Reloading: Implications in Chronic Diseases

    Science.gov (United States)

    Chacon-Cabrera, Alba; Lund-Palau, Helena; Gea, Joaquim; Barreiro, Esther

    2016-01-01

    Background Disuse muscle atrophy is a major comorbidity in patients with chronic diseases including cancer. We sought to explore the kinetics of molecular mechanisms shown to be involved in muscle mass loss throughout time in a mouse model of disuse muscle atrophy and recovery following immobilization. Methods Body and muscle weights, grip strength, muscle phenotype (fiber type composition and morphometry and muscle structural alterations), proteolysis, contractile proteins, systemic troponin I, and mitochondrial content were assessed in gastrocnemius of mice exposed to periods (1, 2, 3, 7, 15 and 30 days) of non-invasive hindlimb immobilization (plastic splint, I cohorts) and in those exposed to reloading for different time-points (1, 3, 7, 15, and 30 days, R cohorts) following a seven-day period of immobilization. Groups of control animals were also used. Results Compared to non-exposed controls, muscle weight, limb strength, slow- and fast-twitch cross-sectional areas, mtDNA/nDNA, and myosin content were decreased in mice of I cohorts, whereas tyrosine release, ubiquitin-proteasome activity, muscle injury and systemic troponin I levels were increased. Gastrocnemius reloading following splint removal improved muscle mass loss, strength, fiber atrophy, injury, myosin content, and mtDNA/nDNA, while reducing ubiquitin-proteasome activity and proteolysis. Conclusions A consistent program of molecular and cellular events leading to reduced gastrocnemius muscle mass and mitochondrial content and reduced strength, enhanced proteolysis, and injury, was seen in this non-invasive mouse model of disuse muscle atrophy. Unloading of the muscle following removal of the splint significantly improved the alterations seen during unloading, characterized by a specific kinetic profile of molecular events involved in muscle regeneration. These findings have implications in patients with chronic diseases including cancer in whom physical activity may be severely compromised. PMID

  7. Slow VO₂ kinetics during moderate-intensity exercise as markers of lower metabolic stability and lower exercise tolerance.

    Science.gov (United States)

    Grassi, Bruno; Porcelli, Simone; Salvadego, Desy; Zoladz, Jerzy A

    2011-03-01

    An analysis of previously published data obtained by our group on patients characterized by markedly slower pulmonary VO₂ kinetics (heart transplant recipients, patients with mitochondrial myopathies, patients with McArdle disease) was carried out in order to suggest that slow VO₂ kinetics should not be considered the direct cause, but rather a marker, of impaired exercise tolerance. For a given ATP turnover rate, faster (or slower) VO₂ kinetics are associated with smaller (or greater) muscle [PCr] decreases. The latter, however, should not be taken per se responsible for the higher (or lower) exercise tolerance, but should be considered within the general concept of "metabolic stability". Good muscle metabolic stability at a given ATP turnover rate (~power output) is associated with relatively smaller decreases, compared to rest, in [PCr] and in the Gibbs free energy of ATP hydrolysis, as well as with relatively smaller increases in [Pi], [ADP(free)], [AMP(free)], and [IMP(free)], metabolites directly related to fatigue. Disturbances in muscle metabolic stability can affect muscle function in various ways, whereas good metabolic stability is associated with less fatigue and higher exercise tolerance. Smaller [PCr] decreases, however, are strictly associated with a faster VO₂ kinetics. Thus, faster VO₂ kinetics may simply be an "epiphenomenon" of a relatively higher metabolic stability, which would then represent the relevant variable in terms of fatigue and exercise tolerance.

  8. Kinetic theory of Jeans instability

    NARCIS (Netherlands)

    Trigger, S.A.; Ershkovic, A.I.; Heijst, van G.J.F.; Schram, P.P.J.M.

    2004-01-01

    Kinetic treatment of the Jeans gravitational instability, with collisions taken into account, is presented. The initial-value problem for the distribution function which obeys the kinetic equation, with the collision integral conserving the number of particles, is solved. Dispersion relation is

  9. Skeletal muscle contraction in protecting joints and bones by absorbing mechanical impacts

    Science.gov (United States)

    Rudenko, O. V.; Tsyuryupa, S.; Sarvazyan, A.

    2016-09-01

    We have previously hypothesized that the dissipation of mechanical energy of external impact is a fundamental function of skeletal muscle in addition to its primary function to convert chemical energy into mechanical energy. In this paper, a mathematical justification of this hypothesis is presented. First, a simple mechanical model, in which the muscle is considered as a simple Hookean spring, is considered. This analysis serves as an introduction to the consideration of a biomechanical model taking into account the molecular mechanism of muscle contraction, kinetics of myosin bridges, sarcomere dynamics, and tension of muscle fibers. It is shown that a muscle behaves like a nonlinear and adaptive spring tempering the force of impact and increasing the duration of the collision. The temporal profiles of muscle reaction to the impact as functions of the levels of muscle contraction, durations of the impact front, and the time constants of myosin bridges closing, are obtained. The absorption of mechanical shock energy is achieved due to the increased viscoelasticity of the contracting skeletal muscle. Controlling the contraction level allows for the optimization of the stiffness and viscosity of the muscle necessary for the protection of the joints and bones.

  10. Human skeletal muscle: transition between fast and slow fibre types.

    Science.gov (United States)

    Neunhäuserer, Daniel; Zebedin, Michaela; Obermoser, Magdalena; Moser, Gerhard; Tauber, Mark; Niebauer, Josef; Resch, Herbert; Galler, Stefan

    2011-05-01

    Human skeletal muscles consist of different fibre types: slow fibres (slow twitch or type I) containing the myosin heavy chain isoform (MHC)-I and fast fibres (fast twitch or type II) containing MHC-IIa (type IIA) or MHC-IId (type IID). The following order of decreasing kinetics is known: type IID > type IIA > type I. This order is especially based on the kinetics of stretch activation, which is the most discriminative property among fibre types. In this study we tested if hybrid fibres containing both MHC-IIa and MHC-I (type C fibres) provide a transition in kinetics between fast (type IIA) and slow fibres (type I). Our data of stretch activation kinetics suggest that type C fibres, with different ratios of MHC-IIa and MHC-I, do not provide a continuous transition. Instead, a specialized group of slow fibres, which we called "transition fibres", seems to provide a transition. Apart of their kinetics of stretch activation, which is most close to that of type IIA, the transition fibres are characterized by large cross-sectional areas and low maximal tensions. The molecular cause for the mechanical properties of the transition fibres is unknown. It is possible that the transition fibres contain an unknown slow MHC isoform, which cannot be separated by biochemical methods. Alternatively, or in addition, isoforms of myofibrillar proteins, other than MHC, and posttranslational modifications of myofibrillar proteins could play a role regarding the characteristics of the transition fibres.

  11. Changes in surface electromyography signals and kinetics associated with progression of fatigue at two speeds during wheelchair propulsion.

    Science.gov (United States)

    Qi, Liping; Wakeling, James; Grange, Simon; Ferguson-Pell, Martin

    2012-01-01

    The purpose of this study was to determine whether muscle balance is influenced by fatigue in a recordable way, toward creating novel defensive activity strategies for manual wheelchair users (MWUs). Wheelchair propulsion to a point of mild fatigue, level 15 on the Rating of Perceived Exertion scale, was investigated at two different speeds. Surface electromyographic (EMG) activity of 7 muscles was recorded on 14 nondisabled participants. Kinetic variables were measured using a SmartWheel. No significant effect was found of percentage endurance time on kinetic variables for the two propulsion speeds. Fatigue-related changes in the EMG spectra were identified as an increase of EMG intensity and a decrease of mean power frequency as a function of percent endurance time for the tested muscles under both fast and slow speed conditions. The greater increases in activity for propulsive muscles compared with recovery muscles during fast speed wheelchair propulsion indicated muscle imbalance associated with fatiguing wheelchair propulsion. This study shows how kinetic and EMG information might be used as feedback to MWUs to ensure that they conduct activity in ways that do not precipitate injury.

  12. Insulin Resistance Is Not Associated with an Impaired Mitochondrial Function in Contracting Gastrocnemius Muscle of Goto-Kakizaki Diabetic Rats In Vivo.

    Directory of Open Access Journals (Sweden)

    Michael Macia

    Full Text Available Insulin resistance, altered lipid metabolism and mitochondrial dysfunction in skeletal muscle would play a major role in type 2 diabetes mellitus (T2DM development, but the causal relationships between these events remain conflicting. To clarify this issue, gastrocnemius muscle function and energetics were investigated throughout a multidisciplinary approach combining in vivo and in vitro measurements in Goto-Kakizaki (GK rats, a non-obese T2DM model developing peripheral insulin resistant without abnormal level of plasma non-esterified fatty acids (NEFA. Wistar rats were used as controls. Mechanical performance and energy metabolism were assessed strictly non-invasively using magnetic resonance (MR imaging and 31-phosphorus MR spectroscopy (31P-MRS. Compared with control group, plasma insulin and glucose were respectively lower and higher in GK rats, but plasma NEFA level was normal. In resting GK muscle, phosphocreatine content was reduced whereas glucose content and intracellular pH were both higher. However, there were not differences between both groups for basal oxidative ATP synthesis rate, citrate synthase activity, and intramyocellular contents for lipids, glycogen, ATP and ADP (an important in vivo mitochondrial regulator. During a standardized fatiguing protocol (6 min of maximal repeated isometric contractions electrically induced at a frequency of 1.7 Hz, mechanical performance and glycolytic ATP production rate were reduced in diabetic animals whereas oxidative ATP production rate, maximal mitochondrial capacity and ATP cost of contraction were not changed. These findings provide in vivo evidence that insulin resistance is not caused by an impairment of mitochondrial function in this diabetic model.

  13. Muscle cooling delays activation of the muscle metaboreflex in humans.

    Science.gov (United States)

    Ray, C A; Hume, K M; Gracey, K H; Mahoney, E T

    1997-11-01

    Elevation of muscle temperature has been shown to increase muscle sympathetic nerve activity (MSNA) during isometric exercise in humans. The purpose of the present study was to evaluate the effect of muscle cooling on MSNA responses during exercise. Eight subjects performed ischemic isometric handgrip at 30% of maximal voluntary contraction to fatigue followed by 2 min of postexercise muscle ischemia (PEMI), with and without local cooling of the forearm. Local cooling of the forearm decreased forearm muscle temperature from 31.8 +/- 0.4 to 23.1 +/- 0.8 degrees C (P = 0.001). Time to fatigue was not different during the control and cold trials (156 +/- 11 and 154 +/- 5 s, respectively). Arterial pressures and heart rate were not significantly affected by muscle cooling during exercise, although heart rate tended to be higher during the second minute of exercise (P = 0.053) during muscle cooling. Exercise-induced increases in MSNA were delayed during handgrip with local cooling compared with control. However, MSNA responses at fatigue and PEMI were not different between the two conditions. These findings suggest that muscle cooling delayed the activation of the muscle metaboreflex during ischemic isometric exercise but did not prevent its full expression during fatiguing contraction. These results support the concept that muscle temperature can play a role in the regulation of MSNA during exercise.

  14. Muscle dysmorphia: current insights

    OpenAIRE

    Tod, David; Edwards, Christian; Cranswick, Ieuan

    2016-01-01

    David Tod1 Christian Edwards2 Ieuan Cranswick1 1School of Sport and Exercise Science, Faculty of Science, Liverpool John Moores University, Liverpool, Merseyside, 2Institute of Sport and Exercise Science, University of Worcester, Worcester, Worcestershire, UK Abstract: Since 1997, there has been increasing research focusing on muscle dysmorphia, a condition underpinned by people’s beliefs that they have insufficient muscularity, in both the Western and non-Western medical and scient...

  15. Kinetics of thyroid hormones

    International Nuclear Information System (INIS)

    Inada, Mitsuo; Nishikawa, Mitsushige; Naito, Kimikazu; Ishii, Hitoshi; Tanaka, Kiyoshi

    1980-01-01

    Kinetics of thyroid hormones were outlined, and recent progress in metabolism of these hormones was also described. Recently, not only T 4 and T 3 but also rT 3 , 3,3'-T 2 , 3',5'-T 2 , and 3,5-T 2 can be measured by RIA. To clarify metabolic pathways of these hormones, metabolic clearance rate and production rate of these hormones were calculated. As single-compartment analysis was insufficient to clarify disappearance curves of thyroid hormones in blood such as T 3 and T 2 of which metabolic speed was so fast, multi-compartment analysis or non-compartment analysis were also performed. Thyroid hormones seemed to be measured more precisely by constant infusion method. At the first step of T 4 metabolism, T 3 was formed by 5'-monodeiodination of T 4 , and rT 3 was formed by 5-monodeiodination of T 4 . As metabolic pathways of T 3 and rT 3 , conversion of them to 3,3'-T 2 or to 3',5'-T 2 and 3,5-T 2 was supposed. This subject will be an interesting research theme in future. (Tsunoda, M.)

  16. MUSCLE TENSION DYSPHONIA

    Directory of Open Access Journals (Sweden)

    Irena Hočevar Boltežar

    2004-07-01

    Full Text Available Background. Muscle tension dysphonia (MTD is the cause of hoarseness in almost one half of the patients with voice disorders. The otorhinolaryngologic examination discovers no evident organic lesions in the larynx at least in the beginning of the voice problems. The reason for the hoarse voice is a disordered and maladjusted activity of the muscles taking part in phonation and/or articulation. In some patients, the irregular function of the larynx results in mucosal lesions on vocal folds. The factors participating in the development of MTD, directly or indirectly influence the quality of laryngeal mucosa, the activity of the phonatory muscles and/or increase of the vocal load. In the diagnostics and treatment of the MTD a phoniatrician, a speech and language therapist and a psychologist closely cooperate with the patient who must take an active role. The treatment is a long-lasting one but resulted in a high percentage of clinical success.Conclusions. Most likely, MTD is not a special disease but only a reflection of any disorder in the complicated system of regulation and realization of phonation. The prognosis of treatment is good when all unfavourable factors participating in development of MTD are eliminated and a proper professional voice- and psychotherapy started.

  17. Dismorfia muscular Muscle dysmorphia

    Directory of Open Access Journals (Sweden)

    Sheila Seleri Marques Assunção

    2002-12-01

    Full Text Available Preocupações mórbidas com a imagem corporal eram tidas até recentemente como problemas eminentemente femininos. Atualmente estas preocupações também têm sido encontradas no sexo masculino. A dismorfia muscular é um subtipo do transtorno dismórfico corporal que ocorre principalmente em homens que, apesar da grande hipertrofia muscular, consideram-se pequenos e fracos. Além de estar associada a prejuízos sociais, ocupacionais, recreativos e em outras áreas do funcionamento do indivíduo, a dismorfia muscular é também um fator de risco para o abuso de esteróides anabolizantes. Este artigo aborda aspectos epidemiológicos, etiológicos e padrões clínicos da dismorfia muscular, além de tecer comentários sobre estratégias de tratamento para este transtorno.Morbid concern over body image was considered, until recently, a female issue. Nowadays, it has been viewed as a common male disorder. Muscle dysmorphia, a subtype of a body dysmorphic disorder, affects men who, despite having clear muscular hypertroph,y see themselves as frail and small. Besides being associated to major social, leisure and occupational dysfunction, muscle dysmorphia is also a risk factor for the abuse of steroids. This article describes epidemiological, etiological and clinical characteristics of muscle dysmorphia and comments on its treatment strategy.

  18. Kinetic effects on magnetohydrodynamic phenomena

    International Nuclear Information System (INIS)

    Naito, Hiroshi; Matsumoto, Taro

    2001-01-01

    Resistive and ideal magnetohydrodynamic (MHD) theories are insufficient to adequately explain MHD phenomena in the high-temperature plasma. Recent progress in numerical simulations concerning kinetic effects on magnetohydrodynamic phenomena is summarized. The following three topics are studied using various models treating extended-MHD phenomena. (1) Kinetic modifications of internal kink modes in tokamaks with normal and reversed magnetic shear configurations. (2) Temporal evolution of the toroidal Alfven eigenmode and fishbone mode in tokamaks with energetic ions. (3) Kinetic stabilization of a title mode in field-reversed configurations by means of anchoring ions and beam ions. (author)

  19. Dynamic {sup 31}P-MR-spectroscopy of the quadriceps muscle. Influence of sex and age on spectroscopic results; Die dynamische 31-Phosphor-Magnetresonanz-Spektroskopie des M. quadriceps. Einfluss von Geschlecht und Alter auf spektroskopische Parameter

    Energy Technology Data Exchange (ETDEWEB)

    Schunk, K.; Romaneehsen, B.; Kessler, S.; Schadmand-Fischer, S.; Thelen, M. [Mainz Univ. (Germany). Klinik und Poliklinik fuer Radiologie

    1999-05-01

    Purpose: {sup 31}P-MRS is used to assess the influence of sex and age on quadriceps muscle metabolism before and after exercise. Materials and Methods: 32 healthy volunteers (15 women, 17 men; mean age: 38{+-}17 yrs.) were examined by dynamic phosphorus-31 ({sup 31}P) magnetic resonance spectroscopy (MRS). In the magnet, the quadriceps muscle was stressed by an isometric and an isotonic form of exercise until exhaustion, respectively. Results: Resting conditions: With increasing subjects` age, the ratio {beta}-adenosine triphosphate/total phosphate decreased (r=-0.37; p=0.02). With increasing subjects` age, the ratios inorganic phosphate/phosphocreatine (r=0.79; p=5x10{sup -8}), phosphomonoester/{beta}-adenosine triphosphate (r=0.74; p=10{sup -6}) and phosphodiester/{beta}-adenosine triphosphate (r=0.62; p=10{sup -4}) increased. The pH was the only one of the evaluated spectroscopic parameters which showed a sex-dependence: Female subjects had a significantly lower pH (7.03{+-}0.02) than male subjects (7.05{+-}0.03; p=0,01). Exercise: With increasing age, the maxima of inorganic phosphate/phosphocreatine were less extreme during both of the exercises (r=-0.42; p=0.0005). Likewise, the exercise-induced acidosis was less severe with increasing age (r=0.53; p=6x10{sup -6}). After the end of the exercise, the times of half recovery of inorganic phosphate/phosphocreatine and the pH correlated neither with the subjects` age nor with sex or cross-sectional area of the quadriceps muscle. Conclusion: Sex and age of volunteers affect spectroscopic results. This influence has to be considered in the interpretation of spectroscopic studies. (orig.) [Deutsch] Ziel: Die Ueberpruefung des Einflusses von Geschlecht und Alter gesunder Probanden auf phosphorspektroskopische Ergebnisse. Material und Methodik: 32 gesunde Probanden (15 Frauen, 17 Maenner) mit einem Durchschnittsalter von 38{+-}17 Jahren wurden mit der dynamischen 31-Phosphor-Magnetresonanz-Spektroskopie (MRS

  20. Respiratory muscle involvement in sarcoidosis.

    Science.gov (United States)

    Schreiber, Tina; Windisch, Wolfram

    2018-07-01

    In sarcoidosis, muscle involvement is common, but mostly asymptomatic. Currently, little is known about respiratory muscle and diaphragm involvement and function in patients with sarcoidosis. Reduced inspiratory muscle strength and/or a reduced diaphragm function may contribute to exertional dyspnea, fatigue and reduced health-related quality of life. Previous studies using volitional and non-volitional tests demonstrated a reduced inspiratory muscle strength in sarcoidosis compared to control subjects, and also showed that respiratory muscle function may even be significantly impaired in a subset of patients. Areas covered: This review examines the evidence on respiratory muscle involvement and its implications in sarcoidosis with emphasis on pathogenesis, diagnosis and treatment of respiratory muscle dysfunction. The presented evidence was identified by a literature search performed in PubMed and Medline for articles about respiratory and skeletal muscle function in sarcoidosis through to January 2018. Expert commentary: Respiratory muscle involvement in sarcoidosis is an underdiagnosed condition, which may have an important impact on dyspnea and health-related quality of life. Further studies are needed to understand the etiology, pathogenesis and extent of respiratory muscle involvement in sarcoidosis.

  1. Vitamin D and muscle trophicity.

    Science.gov (United States)

    Domingues-Faria, Carla; Boirie, Yves; Walrand, Stéphane

    2017-05-01

    We review recent findings on the involvement of vitamin D in skeletal muscle trophicity. Vitamin D deficiencies are associated with reduced muscle mass and strength, and its supplementation seems effective to improve these parameters in vitamin D-deficient study participants. Latest investigations have also evidenced that vitamin D is essential in muscle development and repair. In particular, it modulates skeletal muscle cell proliferation and differentiation. However, discrepancies still exist about an enhancement or a decrease of muscle proliferation and differentiation by the vitamin D. Recently, it has been demonstrated that vitamin D influences skeletal muscle cell metabolism as it seems to regulate protein synthesis and mitochondrial function. Finally, apart from its genomic and nongenomic effects, recent investigations have demonstrated a genetic contribution of vitamin D to muscle functioning. Recent studies support the importance of vitamin D in muscle health, and the impact of its deficiency in regard to muscle mass and function. These 'trophic' properties are of particular importance for some specific populations such as elderly persons and athletes, and in situations of loss of muscle mass or function, particularly in the context of chronic diseases.

  2. Continuous Release of Tumor-Derived Factors Improves the Modeling of Cachexia in Muscle Cell Culture

    Directory of Open Access Journals (Sweden)

    Robert W. Jackman

    2017-09-01

    Full Text Available Cachexia is strongly associated with a poor prognosis in cancer patients but the biological trigger is unknown and therefore no therapeutics exist. The loss of skeletal muscle is the most deleterious aspect of cachexia and it appears to depend on secretions from tumor cells. Models for studying wasting in cell culture consist of experiments where skeletal muscle cells are incubated with medium conditioned by tumor cells. This has led to candidates for cachectic factors but some of the features of cachexia in vivo are not yet well-modeled in cell culture experiments. Mouse myotube atrophy measured by myotube diameter in response to medium conditioned by mouse colon carcinoma cells (C26 is consistently less than what is seen in muscles of mice bearing C26 tumors with moderate to severe cachexia. One possible reason for this discrepancy is that in vivo the C26 tumor and skeletal muscle share a circulatory system exposing the muscle to tumor factors in a constant and increasing way. We have applied Transwell®-adapted cell culture conditions to more closely simulate conditions found in vivo where muscle is exposed to the ongoing kinetics of constant tumor secretion of active factors. C26 cells were incubated on a microporous membrane (a Transwell® insert that constitutes the upper compartment of wells containing plated myotubes. In this model, myotubes are exposed to a constant supply of cancer cell secretions in the medium but without direct contact with the cancer cells, analogous to a shared circulation of muscle and cancer cells in tumor-bearing animals. The results for myotube diameter support the idea that the use of Transwell® inserts serves as a more physiological model of the muscle wasting associated with cancer cachexia than the bolus addition of cancer cell conditioned medium. The Transwell® model supports the notion that the dose and kinetics of cachectic factor delivery to muscle play a significant role in the extent of pathology.

  3. Differential metabolic effects of casein and soy protein meals on skeletal muscle in healthy volunteers.

    Science.gov (United States)

    Luiking, Yvette C; Engelen, Mariëlle P K J; Soeters, Peter B; Boirie, Yves; Deutz, Nicolaas E P

    2011-02-01

    Dietary protein intake is known to affect whole body and interorgan protein turnover. We examined if moderate-nitrogen and carbohydrate casein and soy meals have a different effect on skeletal muscle protein and amino acid kinetics in healthy young subjects. Muscle protein and amino acid kinetics were measured in the postabsorptive state and during 4-h enteral intake of isonitrogenous [0.21 g protein/(kg body weight. 4 h)] protein-based test meals, which contained either casein (CAPM; n = 12) or soy protein (SOPM; n = 10) in 2 separate groups. Stable isotope and muscle biopsy techniques were used to study metabolic effects. The net uptake of glutamate, serine, histidine, and lysine across the leg was larger during CAPM than during SOPM intake. Muscle concentrations of glutamate, serine, histidine, glutamine, isoleucine and BCAA changed differently after CAPM and SOPM (P CAPM and SOPM, but differences in their (net) breakdown rates were not significant. Muscle protein synthesis was not different between CAPM and SOPM. Moderate-nitrogen casein and soy protein meals differently alter leg amino acid uptake without a significant difference in influencing acute muscle protein metabolism. Copyright © 2010 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.

  4. Bicarbonate kinetics in Indian males

    Indian Academy of Sciences (India)

    Madhu

    ized kinetics of bicarbonate using a three-compartment model, to assess which compartmental fluxes changed dur- .... total VCO2 was < 3 % and the average respiratory quotient ..... a part of the nonrespiratory losses of 13CO2 occur to this.

  5. Kinetic equations in dirty superconductors

    International Nuclear Information System (INIS)

    Kraehenbuehl, Y.

    1981-01-01

    Kinetic equations for superconductors in the dirty limit are derived using a method developed for superfluid systems, which allows a systematic expansion in small parameters; exact charge conservation is obeyed. (orig.)

  6. Nuclear Positioning in Muscle Development and Disease

    OpenAIRE

    Eric eFolker; Mary eBaylies

    2013-01-01

    Muscle disease as a group is characterized by muscle weakness, muscle loss, and impaired muscle function. Although the phenotype is the same, the underlying cellular pathologies, and the molecular causes of these pathologies, are diverse. One common feature of many muscle disorders is the mispositioning of myonuclei. In unaffected individuals myonuclei are spaced throughout the periphery of the muscle fiber such that the distance between nuclei is maximized. However, in diseased muscles, th...

  7. Pneumatic Artificial Muscles Based on Biomechanical Characteristics of Human Muscles

    Directory of Open Access Journals (Sweden)

    N. Saga

    2006-01-01

    Full Text Available This article reports the pneumatic artificial muscles based on biomechanical characteristics of human muscles. A wearable device and a rehabilitation robot that assist a human muscle should have characteristics similar to those of human muscle. In addition, since the wearable device and the rehabilitation robot should be light, an actuator with a high power to weight ratio is needed. At present, the McKibben type is widely used as an artificial muscle, but in fact its physical model is highly nonlinear. Therefore, an artificial muscle actuator has been developed in which high-strength carbon fibres have been built into the silicone tube. However, its contraction rate is smaller than the actual biological muscles. On the other hand, if an artificial muscle that contracts axially is installed in a robot as compactly as the robot hand, big installing space is required. Therefore, an artificial muscle with a high contraction rate and a tendon-driven system as a compact actuator were developed, respectively. In this study, we report on the basic structure and basic characteristics of two types of actuators.

  8. Cell kinetics and therapeutic efficiency

    International Nuclear Information System (INIS)

    Andreeff, M.; Abenhardt, W.; Gruner, B.; Stoffner, D.; Mainz Univ.

    1976-01-01

    The study shows that cell kinetics effects correlate with the effects of cytostatic drugs in the tumour model investigated here. It should, however, be noted that even genetically related tumour cell types may react differently to the same cytostatic drug, and that the cell kinetics effects, due to the changes in the cell cycle, cannot be predicted but should be followed with a very fast method, e.g. sequential flan fluorescence cytophotometry, for optimal therapeutic results. (orig./GSE) [de

  9. Use of muscle synergies and wavelet transforms to identify fatigue during squatting.

    Science.gov (United States)

    Smale, Kenneth B; Shourijeh, Mohammad S; Benoit, Daniel L

    2016-06-01

    The objective of this study was to supplement continuous wavelet transforms with muscle synergies in a fatigue analysis to better describe the combination of decreased firing frequency and altered activation profiles during dynamic muscle contractions. Nine healthy young individuals completed the dynamic tasks before and after they squatted with a standard Olympic bar until complete exhaustion. Electromyography (EMG) profiles were analyzed with a novel concatenated non-negative matrix factorization method that decomposed EMG signals into muscle synergies. Muscle synergy analysis provides the activation pattern of the muscles while continuous wavelet transforms output the temporal frequency content of the EMG signals. Synergy analysis revealed subtle changes in two-legged squatting after fatigue while differences in one-legged squatting were more pronounced and included the shift from a general co-activation of muscles in the pre-fatigue state to a knee extensor dominant weighting post-fatigue. Continuous wavelet transforms showed major frequency content decreases in two-legged squatting after fatigue while very few frequency changes occurred in one-legged squatting. It was observed that the combination of methods is an effective way of describing muscle fatigue and that muscle activation patterns play a very important role in maintaining the overall joint kinetics after fatigue. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Smooth muscle myosin light chain kinase efficiently phosphorylates serine 15 of cardiac myosin regulatory light chain

    International Nuclear Information System (INIS)

    Josephson, Matthew P.; Sikkink, Laura A.; Penheiter, Alan R.; Burghardt, Thomas P.; Ajtai, Katalin

    2011-01-01

    Highlights: ► Cardiac myosin regulatory light chain (MYL2) is phosphorylated at S15. ► Smooth muscle myosin light chain kinase (smMLCK) is a ubiquitous kinase. ► It is a widely believed that MYL2 is a poor substrate for smMLCK. ► In fact, smMLCK efficiently and rapidly phosphorylates S15 in MYL2. ► Phosphorylation kinetics measured by novel fluorescence method without radioactivity. -- Abstract: Specific phosphorylation of the human ventricular cardiac myosin regulatory light chain (MYL2) modifies the protein at S15. This modification affects MYL2 secondary structure and modulates the Ca 2+ sensitivity of contraction in cardiac tissue. Smooth muscle myosin light chain kinase (smMLCK) is a ubiquitous kinase prevalent in uterus and present in other contracting tissues including cardiac muscle. The recombinant 130 kDa (short) smMLCK phosphorylated S15 in MYL2 in vitro. Specific modification of S15 was verified using the direct detection of the phospho group on S15 with mass spectrometry. SmMLCK also specifically phosphorylated myosin regulatory light chain S15 in porcine ventricular myosin and chicken gizzard smooth muscle myosin (S20 in smooth muscle) but failed to phosphorylate the myosin regulatory light chain in rabbit skeletal myosin. Phosphorylation kinetics, measured using a novel fluorescence method eliminating the use of radioactive isotopes, indicates similar Michaelis–Menten V max and K M for regulatory light chain S15 phosphorylation rates in MYL2, porcine ventricular myosin, and chicken gizzard myosin. These data demonstrate that smMLCK is a specific and efficient kinase for the in vitro phosphorylation of MYL2, cardiac, and smooth muscle myosin. Whether smMLCK plays a role in cardiac muscle regulation or response to a disease causing stimulus is unclear but it should be considered a potentially significant kinase in cardiac tissue on the basis of its specificity, kinetics, and tissue expression.

  11. Kinetic parameters from thermogravimetric analysis

    Science.gov (United States)

    Kiefer, Richard L.

    1993-01-01

    High performance polymeric materials are finding increased use in aerospace applications. Proposed high speed aircraft will require materials to withstand high temperatures in an oxidative atmosphere for long periods of time. It is essential that accurate estimates be made of the performance of these materials at the given conditions of temperature and time. Temperatures of 350 F (177 C) and times of 60,000 to 100,000 hours are anticipated. In order to survey a large number of high performance polymeric materials on a reasonable time scale, some form of accelerated testing must be performed. A knowledge of the rate of a process can be used to predict the lifetime of that process. Thermogravimetric analysis (TGA) has frequently been used to determine kinetic information for degradation reactions in polymeric materials. Flynn and Wall studied a number of methods for using TGA experiments to determine kinetic information in polymer reactions. Kinetic parameters, such as the apparent activation energy and the frequency factor, can be determined in such experiments. Recently, researchers at the McDonnell Douglas Research Laboratory suggested that a graph of the logarithm of the frequency factor against the apparent activation energy can be used to predict long-term thermo-oxidative stability for polymeric materials. Such a graph has been called a kinetic map. In this study, thermogravimetric analyses were performed in air to study the thermo-oxidative degradation of several high performance polymers and to plot their kinetic parameters on a kinetic map.

  12. Ultrasound of skeletal muscle injury.

    Science.gov (United States)

    Koh, Eamon Su Chun; McNally, Eugene G

    2007-06-01

    The professional and recreational demands of modern society make the treatment of muscle injury an increasingly important clinical problem, particularly in the athletic population. In the elite athlete, significant financial and professional pressures may also exist that emphasize the need for accurate diagnosis and treatment. With new advances in ultrasound technology, images of exquisite detail allow diagnosis of muscle injury that matches the accuracy of magnetic resonance imaging (MRI). Furthermore, the benefits of real-time and Doppler imaging, ability to perform interventional procedures, and relative cost benefits compared with MRI place ultrasound at the forefront for investigation for these injuries in many circumstances. Muscle injury may be divided into acute and chronic pathology, with muscle strain injury the most common clinical problem presenting to sports physicians. This article reviews the spectrum of acute and chronic muscle injuries, with particular attention to clinical features and some common or important muscle strain injuries.

  13. Influence of Prolonged Spaceflight on Heart Rate and Oxygen Uptake Kinetics

    Science.gov (United States)

    Hoffmann, U.; Moore, A.; Drescher, U.

    2013-02-01

    During prolonged spaceflight, physical training is used to minimize cardiovascular deconditioning. Measurement of the kinetics of cardiorespiratory parameters, in particular the kinetic analysis of heart rate, respiratory and muscular oxygen uptake, provides useful information with regard to the efficiency and regulation of the cardiorespiratory system. Practically, oxygen uptake kinetics can only be measured at the lung site (V’O2 resp). The dynamics of V’O2 resp, however, is not identical with the dynamics at the site of interest: skeletal muscle. Eight Astronauts were tested pre- and post-flight using pseudo random binary workload changes between 30 and 80 W. Their kinetic responses of heart rate, respiratory as well as muscular V’O2 kinetics were estimated by using time-series analysis. Statistical analysis revealed that the kinetic responses of respiratory as well as muscular V’O2 kinetics are slowed post-flight than pre-flight. Heart rate seems not to be influenced following flight. The influence of other factors (e. g. astronauts’ exercise training) may impact these parameters and is an area for future studies.

  14. Muscle necrosis - computer tomography aspects

    International Nuclear Information System (INIS)

    Franze, I.; Goebel, N.; Stuckmann, G.

    1985-01-01

    In four patients muscle necroses were observed. In two patients these were caused by intraoperative positioning, in one by having worked with a pneumatic hammer and in one possibly by alcohol. CT showed hypodense areas in the affected muscles which were - in the state of subacute necroses - surrounded by hyperaemic borders. The diagnosis was confirmed by puncture or biopsy. After six months hypodense areas were still perceptible in the atrophic muscles of two patients. (orig.) [de

  15. Muscle dysmorphia: current insights

    Directory of Open Access Journals (Sweden)

    Tod D

    2016-08-01

    Full Text Available David Tod1 Christian Edwards2 Ieuan Cranswick1 1School of Sport and Exercise Science, Faculty of Science, Liverpool John Moores University, Liverpool, Merseyside, 2Institute of Sport and Exercise Science, University of Worcester, Worcester, Worcestershire, UK Abstract: Since 1997, there has been increasing research focusing on muscle dysmorphia, a condition underpinned by people’s beliefs that they have insufficient muscularity, in both the Western and non-Western medical and scientific communities. Much of this empirical interest has surveyed nonclinical samples, and there is limited understanding of people with the condition beyond knowledge about their characteristics. Much of the existing knowledge about people with the condition is unsurprising and inherent in the definition of the disorder, such as dissatisfaction with muscularity and adherence to muscle-building activities. Only recently have investigators started to explore questions beyond these limited tautological findings that may give rise to substantial knowledge advances, such as the examination of masculine and feminine norms. There is limited understanding of additional topics such as etiology, prevalence, nosology, prognosis, and treatment. Further, the evidence is largely based on a small number of unstandardized case reports and descriptive studies (involving small samples, which are largely confined to Western (North American, British, and Australian males. Although much research has been undertaken since the term “muscle dysmorphia” entered the psychiatric lexicon in 1997, there remains tremendous scope for knowledge advancement. A primary task in the short term is for investigators to examine the extent to which the condition exists among well-defined populations to help determine the justification for research funding relative to other public health issues. A greater variety of research questions and designs may contribute to a broader and more robust knowledge base

  16. Muscle dysmorphia: current insights.

    Science.gov (United States)

    Tod, David; Edwards, Christian; Cranswick, Ieuan

    2016-01-01

    Since 1997, there has been increasing research focusing on muscle dysmorphia, a condition underpinned by people's beliefs that they have insufficient muscularity, in both the Western and non-Western medical and scientific communities. Much of this empirical interest has surveyed nonclinical samples, and there is limited understanding of people with the condition beyond knowledge about their characteristics. Much of the existing knowledge about people with the condition is unsurprising and inherent in the definition of the disorder, such as dissatisfaction with muscularity and adherence to muscle-building activities. Only recently have investigators started to explore questions beyond these limited tautological findings that may give rise to substantial knowledge advances, such as the examination of masculine and feminine norms. There is limited understanding of additional topics such as etiology, prevalence, nosology, prognosis, and treatment. Further, the evidence is largely based on a small number of unstandardized case reports and descriptive studies (involving small samples), which are largely confined to Western (North American, British, and Australian) males. Although much research has been undertaken since the term "muscle dysmorphia" entered the psychiatric lexicon in 1997, there remains tremendous scope for knowledge advancement. A primary task in the short term is for investigators to examine the extent to which the condition exists among well-defined populations to help determine the justification for research funding relative to other public health issues. A greater variety of research questions and designs may contribute to a broader and more robust knowledge base than currently exists. Future work will help clinicians assist a group of people whose quality of life and health are placed at risk by their muscular preoccupation.

  17. Lipoxygenase in chicken muscle

    International Nuclear Information System (INIS)

    Grossman, S.; Bergman, M.; Sklan, D.

    1988-01-01

    The presence of lipoxygenase-type enzymes was demonstrated in chick muscles. Examination of the oxidation products of [ 14 C]arachidonic acid revealed the presence of 15-lipoxygenase. The enzyme was partially purified by affinity chromatography on linoleoyl-aminoethyl-Sepharose. The enzyme was stable on frozen storage, and activity was almost completely preserved after 12-month storage at -20 degree C. During this period the content of cis,cis-1,4-pentadiene fatty acids decreased slightly. It is suggested that lipoxygenase may be responsible for some of the oxidative changes occurring in fatty acids on frozen storage of chicken meat

  18. Coding in Muscle Disease.

    Science.gov (United States)

    Jones, Lyell K; Ney, John P

    2016-12-01

    Accurate coding is critically important for clinical practice and research. Ongoing changes to diagnostic and billing codes require the clinician to stay abreast of coding updates. Payment for health care services, data sets for health services research, and reporting for medical quality improvement all require accurate administrative coding. This article provides an overview of administrative coding for patients with muscle disease and includes a case-based review of diagnostic and Evaluation and Management (E/M) coding principles in patients with myopathy. Procedural coding for electrodiagnostic studies and neuromuscular ultrasound is also reviewed.

  19. Idiopathic masseter muscle hypertrophy.

    Science.gov (United States)

    Kebede, Biruktawit; Megersa, Shimalis

    2011-11-01

    Benign Masseteric Hypertrophy is a relatively uncommon condition that can occur unilaterally or bilaterally. Pain may be a symptom, but most frequently a clinician is consulted for cosmetic reasons. In some cases prominent Exostoses at the angle of the mandible are noted. Although it is tempting to point to Malocclusion, Bruxism, clenching, or Temporomandibular joint disorders, the etiology in the majority of cases is unclear. Diagnosis is based on awareness of the condition, clinical and radiographic findings, and exclusion of more serious Pathology such as Benign and Malignant Parotid Disease, Rhabdomyoma, and Lymphangioma. Treatment usually involves resection of a portion of the Masseter muscle with or without the underlying bone.

  20. Contractures and muscle disease.

    Science.gov (United States)

    Walters, R Jon

    2016-08-01

    Contractures are one of a handful of signs in muscle disease, besides weakness and its distribution, whose presence can help guide us diagnostically, a welcome star on the horizon. Contractures are associated with several myopathies, some with important cardiac manifestations, and consequently are important to recognise; their presence may also provide us with a potential satisfying 'penny dropping' diagnostic moment. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

  1. New twist on artificial muscles.

    Science.gov (United States)

    Haines, Carter S; Li, Na; Spinks, Geoffrey M; Aliev, Ali E; Di, Jiangtao; Baughman, Ray H

    2016-10-18

    Lightweight artificial muscle fibers that can match the large tensile stroke of natural muscles have been elusive. In particular, low stroke, limited cycle life, and inefficient energy conversion have combined with high cost and hysteretic performance to restrict practical use. In recent years, a new class of artificial muscles, based on highly twisted fibers, has emerged that can deliver more than 2,000 J/kg of specific work during muscle contraction, compared with just 40 J/kg for natural muscle. Thermally actuated muscles made from ordinary polymer fibers can deliver long-life, hysteresis-free tensile strokes of more than 30% and torsional actuation capable of spinning a paddle at speeds of more than 100,000 rpm. In this perspective, we explore the mechanisms and potential applications of present twisted fiber muscles and the future opportunities and challenges for developing twisted muscles having improved cycle rates, efficiencies, and functionality. We also demonstrate artificial muscle sewing threads and textiles and coiled structures that exhibit nearly unlimited actuation strokes. In addition to robotics and prosthetics, future applications include smart textiles that change breathability in response to temperature and moisture and window shutters that automatically open and close to conserve energy.

  2. Muscle regeneration in mitochondrial myopathies

    DEFF Research Database (Denmark)

    Krag, T O; Hauerslev, S; Jeppesen, T D

    2013-01-01

    Mitochondrial myopathies cover a diverse group of disorders in which ragged red and COX-negative fibers are common findings on muscle morphology. In contrast, muscle degeneration and regeneration, typically found in muscular dystrophies, are not considered characteristic features of mitochondrial...... myopathies. We investigated regeneration in muscle biopsies from 61 genetically well-defined patients affected by mitochondrial myopathy. Our results show that the perturbed energy metabolism in mitochondrial myopathies causes ongoing muscle regeneration in a majority of patients, and some were even affected...

  3. Gyrocenter-gauge kinetic theory

    International Nuclear Information System (INIS)

    Qin, H.; Tang, W.M.; Lee, W.W.

    2000-01-01

    Gyrocenter-gauge kinetic theory is developed as an extension of the existing gyrokinetic theories. In essence, the formalism introduced here is a kinetic description of magnetized plasmas in the gyrocenter coordinates which is fully equivalent to the Vlasov-Maxwell system in the particle coordinates. In particular, provided the gyroradius is smaller than the scale-length of the magnetic field, it can treat high frequency range as well as the usual low frequency range normally associated with gyrokinetic approaches. A significant advantage of this formalism is that it enables the direct particle-in-cell simulations of compressional Alfven waves for MHD applications and of RF waves relevant to plasma heating in space and laboratory plasmas. The gyrocenter-gauge kinetic susceptibility for arbitrary wavelength and arbitrary frequency electromagnetic perturbations in a homogeneous magnetized plasma is shown to recover exactly the classical result obtained by integrating the Vlasov-Maxwell system in the particle coordinates. This demonstrates that all the waves supported by the Vlasov-Maxwell system can be studied using the gyrocenter-gauge kinetic model in the gyrocenter coordinates. This theoretical approach is so named to distinguish it from the existing gyrokinetic theory, which has been successfully developed and applied to many important low-frequency and long parallel wavelength problems, where the conventional meaning of gyrokinetic has been standardized. Besides the usual gyrokinetic distribution function, the gyrocenter-gauge kinetic theory emphasizes as well the gyrocenter-gauge distribution function, which sometimes contains all the physics of the problems being studied, and whose importance has not been realized previously. The gyrocenter-gauge distribution function enters Maxwell's equations through the pull-back transformation of the gyrocenter transformation, which depends on the perturbed fields. The efficacy of the gyrocenter-gauge kinetic approach is

  4. Crystallization Kinetics within a Generic Modelling Framework

    DEFF Research Database (Denmark)

    Meisler, Kresten Troelstrup; von Solms, Nicolas; Gernaey, Krist

    2013-01-01

    An existing generic modelling framework has been expanded with tools for kinetic model analysis. The analysis of kinetics is carried out within the framework where kinetic constitutive models are collected, analysed and utilized for the simulation of crystallization operations. A modelling...... procedure is proposed to gain the information of crystallization operation kinetic model analysis and utilize this for faster evaluation of crystallization operations....

  5. Biomechanics and muscle coordination of human walking. Part I: introduction to concepts, power transfer, dynamics and simulations.

    Science.gov (United States)

    Zajac, Felix E; Neptune, Richard R; Kautz, Steven A

    2002-12-01

    Current understanding of how muscles coordinate walking in humans is derived from analyses of body motion, ground reaction force and EMG measurements. This is Part I of a two-part review that emphasizes how muscle-driven dynamics-based simulations assist in the understanding of individual muscle function in walking, especially the causal relationships between muscle force generation and walking kinematics and kinetics. Part I reviews the strengths and limitations of Newton-Euler inverse dynamics and dynamical simulations, including the ability of each to find the contributions of individual muscles to the acceleration/deceleration of the body segments. We caution against using the concept of biarticular muscles transferring power from one joint to another to infer muscle coordination principles because energy flow among segments, even the adjacent segments associated with the joints, cannot be inferred from computation of joint powers and segmental angular velocities alone. Rather, we encourage the use of dynamical simulations to perform muscle-induced segmental acceleration and power analyses. Such analyses have shown that the exchange of segmental energy caused by the forces or accelerations induced by a muscle can be fundamentally invariant to whether the muscle is shortening, lengthening, or neither. How simulation analyses lead to understanding the coordination of seated pedaling, rather than walking, is discussed in this first part because the dynamics of pedaling are much simpler, allowing important concepts to be revealed. We elucidate how energy produced by muscles is delivered to the crank through the synergistic action of other non-energy producing muscles; specifically, that a major function performed by a muscle arises from the instantaneous segmental accelerations and redistribution of segmental energy throughout the body caused by its force generation. Part II reviews how dynamical simulations provide insight into muscle coordination of walking.

  6. Human skeletal muscle fibroblasts stimulate in vitro myogenesis and in vivo muscle regeneration

    DEFF Research Database (Denmark)

    Mackey, Abigail L.; Magnan, Mélanie; Chazaud, Bénédicte

    2017-01-01

    Accumulation of skeletal muscle extracellular matrix is an unfavourable characteristic of many muscle diseases, muscle injury and sarcopenia. In addition to the indispensable role satellite cells play in muscle regeneration, there is emerging evidence in rodents for a regulatory influence...

  7. Nutritional interventions to preserve skeletal muscle mass

    NARCIS (Netherlands)

    Backx, Evelien M.P.

    2016-01-01

    Muscle mass is the main predictor for muscle strength and physical function. The amount of muscle mass can decline rapidly during periods of reduced physical activity or during periods of energy intake restriction. For athletes, it is important to maintain muscle mass, since the loss of muscle is

  8. Muscle-bone Interactions During Fracture Healing

    Science.gov (United States)

    2015-03-01

    muscle resection, isotopic or heterotopic minced muscle implants were placed immediately adjacent to the periosteum. Their control groups consisted of...interacting with surrounding muscle. Addition- ally, Utvag et al. showed that significant muscle injury and ab- sence of muscle by resection, or by traumatic

  9. Thick filament mechano-sensing is a calcium-independent regulatory mechanism in skeletal muscle.

    Science.gov (United States)

    Fusi, L; Brunello, E; Yan, Z; Irving, M

    2016-10-31

    Recent X-ray diffraction studies on actively contracting fibres from skeletal muscle showed that the number of myosin motors available to interact with actin-containing thin filaments is controlled by the stress in the myosin-containing thick filaments. Those results suggested that thick filament mechano-sensing might constitute a novel regulatory mechanism in striated muscles that acts independently of the well-known thin filament-mediated calcium signalling pathway. Here we test that hypothesis using probes attached to the myosin regulatory light chain in demembranated muscle fibres. We show that both the extent and kinetics of thick filament activation depend on thick filament stress but are independent of intracellular calcium concentration in the physiological range. These results establish direct control of myosin motors by thick filament mechano-sensing as a general regulatory mechanism in skeletal muscle that is independent of the canonical calcium signalling pathway.

  10. [Statins and muscle pain].

    Science.gov (United States)

    Yosef, Yoni; Schurr, Daniel; Constantini, Naama

    2014-07-01

    Statins are used for the prevention and treatment of cardiovascular disease. The treatment is quite safe but not free of side effects, particularly muscle pain. Fear of pain may prevent patients from carrying out exercise or diminish their motivation to return and engage in it, even though both the statins and the exercise have a proven benefit in both treatment and prevention, and a synergistic effect enhances this benefit. Prevalence of muscular pain ranges from 1-30%. Pain usually appears at the beginning of treatment, but can occur even after months and under any of the existing agents. The creatine phosphokinase (CPK) enzyme level may rise, but not necessarily. Increases to exceptional values (10 times the upper normal level) are relatively rare and rhabdomyolysis is extremely rare. The risk increases with age, co-morbidities and especially when taken concurrently with drugs that are metabolized in a similar pathway. Pain usually passes within a month after discontinuing treatment, but may persist for six months or more. Studies have examined the effect of statin therapy on the ability to perform physical activity, but results are inconsistent. The increased rise of CPK was observed under statin therapy, a tendency that increased with age. However, it was not accompanied by an increased incidence of muscle pain or rhabdomyolysis. Considering the above we recommend encouraging patients to exercise. However, patients should be instructed to report new or worsening muscular pains. Discontinuation, lowering dose or replacement should be considered when pain is suspected to be related with treatment.

  11. The association between premature plantarflexor muscle activity, muscle strength, and equinus gait in patients with various pathologies.

    Science.gov (United States)

    Schweizer, Katrin; Romkes, Jacqueline; Brunner, Reinald

    2013-09-01

    This study provides an overview on the association between premature plantarflexor muscle activity (PPF), muscle strength, and equinus gait in patients with various pathologies. The purpose was to evaluate whether muscular weakness and biomechanical alterations are aetiological factors for PPF during walking, independent of the underlying pathology. In a retrospective design, 716 patients from our clinical database with 46 different pathologies (orthopaedic and neurologic) were evaluated. Gait analysis data of the patients included kinematics, kinetics, electromyographic activity (EMG) data, and manual muscle strength testing. All patients were clustered three times. First, patients were grouped according to their primary pathology. Second, all patients were again clustered, this time according to their impaired joints. Third, groups of patients with normal EMG or PPF, and equinus or normal foot contact were formed to evaluate the association between PPF and equinus gait. The patient groups derived by the first two cluster methods were further subdivided into patients with normal or reduced muscle strength. Additionally, the phi correlation coefficient was calculated between PPF and equinus gait. Independent of the clustering, PPF was present in all patient groups. Weak patients revealed PPF more frequently. The correlations of PPF and equinus gait were lower than expected, due to patients with normal EMG during loading response and equinus. These patients, however, showed higher gastrocnemius activity prior to foot strike together with lower peak tibialis anterior muscle activity in loading response. Patients with PPF and a normal foot contact possibly apply the plantarflexion-knee extension couple during loading response. While increased gastrocnemius activity around foot strike seems essential for equinus gait, premature gastrocnemius activity does not necessarily produce an equinus gait. We conclude that premature gastrocnemius activity is strongly associated

  12. Open versus closed kinetic chain exercises for patellar chondromalacia.

    Science.gov (United States)

    Bakhtiary, A H; Fatemi, E

    2008-02-01

    Conservative treatment of patellar chondromalacia has been the subject of several studies. One recommended treatment is a strengthening exercise of the quadriceps muscle, which may be performed in closed or open kinetic chains. This study was designed to compare the effect of straight leg raise (SLR) and semi-squat exercises on the treatment of patellar chondromalacia, which has not been done to date. 32 female university students with a diagnosis of patellar chondromalacia were randomly assigned to two experimental groups: SLR and semi-squat exercise. Before starting exercise protocols, Q angle, maximal isometric voluntary contraction force (MIVCF) of quadriceps, crepitation, circumference of thigh 5 and 10 cm above the patella and patellofemoral pain according to the visual analogue scale (VAS) were assessed. Both groups then followed a 3-week programme of quadriceps muscle strengthening exercises (SLR or semi-squat) starting with 20 exercises twice a day and increasing each session by 5 exercises every 2 days. All measurements were repeated at the end of each week and then again 2 weeks after the 3-week exercise programme. Reduced Q angle (mean differences (SD) 0.8 (0.3), p = 0.016) and crepitation (19.9 (8.5), p = 0.04), and an increase in the MIVCF of the quadriceps (15.8 (5.6), p = 0.01) and thigh circumference (1.5 (0.3), p = 0.001) were found in semi-squat group compared with SLR group. However, patellofemoral pain was decreased significantly in both groups. The results of this study indicate that semi-squat exercises (closed kinetic chain) are more effective than SLR exercise (open kinetic chain) in the treatment of patellar chondromalacia. More studies are needed to investigate the long-term effect of these types of exercise.

  13. Skeletal muscle myofilament adaptations to aging, disease and disuse and their effects on whole muscle performance in older adult humans

    Directory of Open Access Journals (Sweden)

    Mark Stuart Miller

    2014-09-01

    Full Text Available Skeletal muscle contractile function declines with aging, disease and disuse. In vivo muscle contractile function depends on a variety of factors, but force, contractile velocity and power generating capacity ultimately derive from the summed contribution of single muscle fibers. The contractile performance of these fibers are, in turn, dependent upon the isoform and function of myofilament proteins they express, with myosin protein expression and its mechanical and kinetic characteristics playing a predominant role. Alterations in myofilament protein biology, therefore, may contribute to the development of functional limitations and disability in these conditions. Recent studies suggest that these conditions are associated with altered single fiber performance due to decreased expression of myofilament proteins and/or changes in myosin-actin cross-bridge interactions. Furthermore, cellular and myofilament-level adaptations are related to diminished whole muscle and whole body performance. Notably, the effect of these various conditions on myofilament and single fiber function tends to be larger in older women compared to older men, which may partially contribute to their higher rates of disability. To maintain functionality and provide the most appropriate and effective countermeasures to aging, disease and disuse in both sexes, a more thorough understanding is needed of the contribution of myofilament adaptations to functional disability in older men and women and their contribution to tissue level function and mobility impairment.

  14. Calcium regulation and muscle disease.

    NARCIS (Netherlands)

    Gommans, I.M.P.; Vlak, M.; Haan, A. de; Engelen, B.G.M. van

    2002-01-01

    Changes in intracellular Ca2+-concentration play an important role in the excitation-contraction-relaxation cycle of skeletal muscle. In this review we describe various inheritable muscle diseases to highlight the role of Ca2+-regulatory mechanisms. Upon excitation the ryanodine receptor releases

  15. Skeletal muscle regeneration is modulated by inflammation

    Directory of Open Access Journals (Sweden)

    Wenjun Yang

    2018-04-01

    Full Text Available Skeletal muscle regeneration is a complex process orchestrated by multiple steps. Recent findings indicate that inflammatory responses could play central roles in bridging initial muscle injury responses and timely muscle injury reparation. The various types of immune cells and cytokines have crucial roles in muscle regeneration process. In this review, we briefly summarise the functions of acute inflammation in muscle regeneration. The translational potential of this article: Immune system is closely relevant to the muscle regeneration. Understanding the mechanisms of inflammation in muscle regeneration is therefore critical for the development of effective regenerative, and therapeutic strategies in muscular disorders. This review provides information for muscle regeneration research regarding the effects of inflammation on muscle regeneration. Keywords: Chronic muscle disorders, Cytokines, Immune cells, Inflammation, Muscle regeneration, Muscle stem cells

  16. MR imaging of muscle diseases

    International Nuclear Information System (INIS)

    Kaiser, W.A.; Zeitler, E.; Schalke, B.C.G.

    1986-01-01

    Because of high soft-tissue contrast, MR imaging is especially suitable for the investigation of muscle diseases. Between March 1984 and March 1986, 76 patients with different types of muscle diseases were examined using a 1-T superconductive magnet (Siemens Magnetom). Studied were 14 patients with progressive muscular dystrophy (including carriers), 32 patients with myositis, four patients with myotonic dystrophy, six patients with spinal muscular atrophy, and 20 patients with other muscle diseases, including metabolic disorders. MR imaging showed typical signal patterns in affected muscle groups. These patterns can be used in the differential diagnosis, in biopsy planning, or in evaluation of response to therapy. The T1/T2 ratio especially seems to indicate very early stages of muscle disease

  17. Leiomyoma of the sternothyroid muscle.

    Science.gov (United States)

    Rowe, Meghan E; Khorsandi, Azita S; Guerrero, Dominick R; Brett, Elise M; Sarlin, Jonathan; Urken, Mark L

    2016-01-01

    Leiomyomas are benign cutaneous tumors of smooth muscle origin. Only a small percentage of leiomyomas arise in the head and neck region. We present the first case of leiomyoma arising in the sternothyroid muscle of the neck. We analyze the clinical presentation, pathology, and histology for a single case study. The histologic findings of the tumor located in the sternothyroid muscle support the diagnosis of leiomyoma. This is the first case of leiomyoma arising in the sternothyroid muscle, and only the second reported case of leiomyoma in the strap muscles of the neck. Leiomyoma should be included in the differential diagnosis of soft tissue tumors in the head and neck region. A histological analysis is essential in determining both tumor type and subtype, which will inform the proper course of treatment. Copyright © 2016 Elsevier Inc. All rights reserved.

  18. Exercising with blocked muscle glycogenolysis

    DEFF Research Database (Denmark)

    Nielsen, Tue L; Pinós, Tomàs; Brull, Astrid

    2018-01-01

    BACKGROUND: McArdle disease (glycogen storage disease type V) is an inborn error of skeletal muscle metabolism, which affects glycogen phosphorylase (myophosphorylase) activity leading to an inability to break down glycogen. Patients with McArdle disease are exercise intolerant, as muscle glycogen......-derived glucose is unavailable during exercise. Metabolic adaptation to blocked muscle glycogenolysis occurs at rest in the McArdle mouse model, but only in highly glycolytic muscle. However, it is unknown what compensatory metabolic adaptations occur during exercise in McArdle disease. METHODS: In this study, 8......-week old McArdle and wild-type mice were exercised on a treadmill until exhausted. Dissected muscles were compared with non-exercised, age-matched McArdle and wild-type mice for histology and activation and expression of proteins involved in glucose uptake and glycogenolysis. RESULTS: Investigation...

  19. Muscle dysfunction in cancer patients

    DEFF Research Database (Denmark)

    Christensen, Jesper Frank; Jones, L W; Andersen, J L

    2014-01-01

    dysfunction in cancer patients lies in the correlation to vital clinical end points such as cancer-specific and all-cause mortality, therapy complications and quality of life (QoL). Such associations strongly emphasize the need for effective therapeutic countermeasures to be developed and implemented...... implications of muscle dysfunction in cancer patients. The efficacy of exercise training to prevent and/or mitigate cancer-related muscle dysfunction is also discussed. DESIGN: We identified 194 studies examining muscular outcomes in cancer patients by searching PubMed and EMBASE databases. RESULTS: Muscle...... dysfunction is evident across all stages of the cancer trajectory. The causes of cancer-related muscle dysfunction are complex, but may involve a wide range of tumor-, therapy- and/or lifestyle-related factors, depending on the clinical setting of the individual patient. The main importance of muscle...

  20. Contralesional Hemisphere Regulation of Transcranial Magnetic Stimulation-Induced Kinetic Coupling in the Poststroke Lower Limb

    OpenAIRE

    Tan, Andrew Q.; Dhaher, Yasin Y.

    2017-01-01

    Background The neural constraints underlying hemiparetic gait dysfunction are associated with abnormal kinetic outflow and altered muscle synergy structure. Recent evidence from our lab implicates the lesioned hemisphere in mediating the expression of abnormally coupled hip adduction and knee extension synergy, suggesting a role of cortical networks in the regulation of lower limb motor outflow poststroke. The potential contribution of contralesional hemisphere (CON-H) in regulating pareti...

  1. Transformation kinetics for nucleus clusters

    International Nuclear Information System (INIS)

    Villa, Elena; Rios, Paulo R.

    2009-01-01

    A rigorous mathematical approach based on stochastic geometry concepts is presented to extend previous Johnson-Mehl, Avrami, Kolmogorov treatment of transformation kinetics to situations in which nuclei are not homogeneously located in space but are located in clusters. An exact analytical solution is presented here for the first time assuming that nucleation sites follow a Matern cluster process. The influence of Matern cluster process parameters on subsequent growth kinetics and the microstructural path are illustrated by means of numerical examples. Moreover, using the superposition principle, exact analytical solutions are also obtained when nucleation takes place by a combination of a Matern cluster process and an inhomogeneous Poisson point process. The new solutions presented here significantly increase the number of exactly solvable cases available to formal kinetics.

  2. Chapter 22. Cell population kinetics

    International Nuclear Information System (INIS)

    Tubiana, M.

    1975-01-01

    The main contribution of radioisotopes to the development of a new discipline, cell population kinetics, was shown. The aim of this science is to establish, for each tissue of the organism, the life span of its component cells and the mechanisms governing its growth, its differentiation and its homeostasis with respect to outside attacks. Labelling techniques have been used to follow the cells during these various processes. The case of non-dividing cells was considered first, taking as example, the red blood cells of which the lifetime was studied, after which the case of proliferating cells was examined using 14 C- or tritium-labelled thymidine. The methods used to measure the cell cycle parameters were described: labelled-mitosis curve method, double-labelling and continuous labelling methods, proliferation coefficient measurement. Cell kinetics were shown to allow an interpretation of radiobiological data. Finally the practical value of cell kinetics research was shown [fr

  3. Kinetic theory and transport phenomena

    CERN Document Server

    Soto, Rodrigo

    2016-01-01

    This textbook presents kinetic theory, which is a systematic approach to describing nonequilibrium systems. The text is balanced between the fundamental concepts of kinetic theory (irreversibility, transport processes, separation of time scales, conservations, coarse graining, distribution functions, etc.) and the results and predictions of the theory, where the relevant properties of different systems are computed. The book is organised in thematic chapters where different paradigmatic systems are studied. The specific features of these systems are described, building and analysing the appropriate kinetic equations. Specifically, the book considers the classical transport of charges, the dynamics of classical gases, Brownian motion, plasmas, and self-gravitating systems, quantum gases, the electronic transport in solids and, finally, semiconductors. Besides these systems that are studied in detail, concepts are applied to some modern examples including the quark–gluon plasma, the motion of bacterial suspen...

  4. Dynamic cardiomyoplasty using artificial muscle.

    Science.gov (United States)

    Suzuki, Yasuyuki; Daitoku, Kazuyuki; Minakawa, Masahito; Fukui, Kozo; Fukuda, Ikuo

    2008-01-01

    Dynamic cardiomyoplasty using latissimus dorsi muscle was previously used to compensate for congestive heart failure. Now, however, this method is not acceptable because the long-term result was not as expected owing to fatigue of the skeletal muscle. BioMetal fiber developed by Toki Corporation is one of the artificial muscles activated by electric current. The behavior of this fiber is similar to that of organic muscle. We made an artificial muscle like the latissimus dorsi using BioMetal fiber and tested whether we could use this new muscle as a cardiac supporting device. Testing one Biometal fiber showed the following performance: practical use maximal generative force was 30 g, exercise variation was 50%, and the standard driving current was 220 mA. We created a 4 x 12-cm tabular artificial muscle using 8 BioMetal fibers as a cardiac support device. We also made a simulation circuit composed of a 6 x 8-cm soft bag with unidirectional valves, reservoir, and connecting tube. The simulation circuit was filled with water and the soft bag was wrapped with the artificial muscle device. After powering the device electrically at 9 V with a current of 220 mA for each fiber, we measured the inside pressure and observed the movement of the artificial device. The artificial muscle contracted in 0.5 s for peak time and squeezed the soft bag. The peak pressure inside the soft bag was measured as 10 mmHg. Although further work will be needed to enhance the speed of deformability and movement simulating contraction, we conclude that artificial muscle may be potentially useful as a cardiac assistance device that can be developed for dynamic cardiomyoplasty.

  5. Muscling out malaria

    DEFF Research Database (Denmark)

    Hughes, David Peter; Boomsma, Jacobus Jan

    2006-01-01

    ) [2] highlighted the back-to-back articles in Science 3 and 4 that demonstrated the potential biocontrol of malaria by targeting mosquitoes with entomopathogenic fungi (Metarhizium and Beauveria spp.). The wide impact of the original articles and the need to find alternatives to pesticidal control...... where malaria is endemic, humanity cannot afford shortcuts, because any failures owing to poor management or premature implementation will reduce local governmental support rather than enhance it (Andrew Read, pers. commun.). Therefore, if we are to ‘muscle out malaria', well...... of key importance, and the new focus on fungal biocontrol of malaria should therefore act as a catalyst for further research on the basic biology of fungal pathogens. Understanding morphological, biochemical or immune system-based resistance to insect pathogenic fungi will be easier if we know...

  6. Bulk muscles, loose cables.

    Science.gov (United States)

    Liyanage, Chamari R D G; Kodali, Venkata

    2014-10-17

    The accessibility and usage of body building supplements is on the rise with stronger internet marketing strategies by the industry. The dangers posed by the ingredients in them are underestimated. A healthy young man came to the emergency room with palpitations and feeling unwell. Initial history and clinical examination were non-contributory to find the cause. ECG showed atrial fibrillation. A detailed history for any over the counter or herbal medicine use confirmed that he was taking supplements to bulk muscle. One of the components in these supplements is yohimbine; the onset of symptoms coincided with the ingestion of this product and the patient is symptom free after stopping it. This report highlights the dangers to the public of consuming over the counter products with unknown ingredients and the consequential detrimental impact on health. 2014 BMJ Publishing Group Ltd.

  7. Muscle spindle autogenetic inhibition in the extraocular muscles of lamb.

    Science.gov (United States)

    Pettorossi, V E; Filippi, G M

    1981-09-01

    The role of extraocular muscle (EOM) proprioceptors on eye motility has been investigated in lambs on "encéphale isolé", by evaluating the tension of EOMs at various lengths and velocities of stretch before and after proprioceptive blocks. The EOM tension, in the absence of proprioceptive input, was higher than in normal conditions. Such an effect occurred at lengthening values greater than 3 mm of stretch from resting muscle length, corresponding to 18 degrees of eye deviation and was dependent on the velocity of the stretch, being more effective at high velocity. The muscle receptors responsible for this effect was determined by comparing the sensitivity to vibratory stimulation of spindles and tendon organs to the amount of inhibition provoked by the same stimulation on an EOM electromyographic activity. The tension inhibition appeared to be correlated to muscle spindle activation. Thus, the presence of muscle spindles can determine a reduction of the tension within the stretched muscles. This result suggests that the EOM length and velocity signals operate moment to moment reduction on the stiffness of the muscle which antagonizes eye displacement, thus facilitating the ocular movements.

  8. Aerobic metabolism on muscle contraction in porcine gastric smooth muscle.

    Science.gov (United States)

    Kanda, Hidenori; Kaneda, Takeharu; Nagai, Yuta; Urakawa, Norimoto; Shimizu, Kazumasa

    2018-05-18

    Exposure to chronic hypoxic conditions causes various gastric diseases, including gastric ulcers. It has been suggested that gastric smooth muscle contraction is associated with aerobic metabolism. However, there are no reports on the association between gastric smooth muscle contraction and aerobic metabolism, and we have investigated this association in the present study. High K + - and carbachol (CCh)-induced muscle contractions involved increasing O 2 consumption. Aeration with N 2 (hypoxia) and NaCN significantly decreased high K + - and CCh-induced muscle contraction and O 2 consumption. In addition, hypoxia and NaCN significantly decreased creatine phosphate (PCr) contents in the presence of high K + . Moreover, decrease in CCh-induced contraction and O 2 consumption was greater than that of high K + . Our results suggest that hypoxia and NaCN inhibit high K + - and CCh-induced contractions in gastric fundus smooth muscles by decreasing O 2 consumption and intracellular PCr content. However, the inhibition of CCh-induced muscle contraction was greater than that of high K + -induced muscle contraction.

  9. Selected readings in chemical kinetics

    CERN Document Server

    Back, Margaret H

    2013-01-01

    Selected Readings in Chemical Kinetics covers excerpts from 12 papers in the field of general and gas-phase kinetics. The book discusses papers on the laws of connexion between the conditions of a chemical change and its amount; on the reaction velocity of the inversion of the cane sugar by acids; and the calculation in absolute measure of velocity constants and equilibrium constants in gaseous systems. The text then tackles papers on simple gas reactions; on the absolute rate of reactions in condensed phases; on the radiation theory of chemical action; and on the theory of unimolecular reacti

  10. Chemical kinetics and reaction dynamics

    CERN Document Server

    Houston, Paul L

    2006-01-01

    This text teaches the principles underlying modern chemical kinetics in a clear, direct fashion, using several examples to enhance basic understanding. It features solutions to selected problems, with separate sections and appendices that cover more technical applications.Each chapter is self-contained and features an introduction that identifies its basic goals, their significance, and a general plan for their achievement. This text's important aims are to demonstrate that the basic kinetic principles are essential to the solution of modern chemical problems, and to show how the underlying qu

  11. Chemical kinetics and combustion modeling

    Energy Technology Data Exchange (ETDEWEB)

    Miller, J.A. [Sandia National Laboratories, Livermore, CA (United States)

    1993-12-01

    The goal of this program is to gain qualitative insight into how pollutants are formed in combustion systems and to develop quantitative mathematical models to predict their formation rates. The approach is an integrated one, combining low-pressure flame experiments, chemical kinetics modeling, theory, and kinetics experiments to gain as clear a picture as possible of the process in question. These efforts are focused on problems involved with the nitrogen chemistry of combustion systems and on the formation of soot and PAH in flames.

  12. Deuteration kinetics of the graphene

    Energy Technology Data Exchange (ETDEWEB)

    Nefedov, Alexei; Woell, Christof [KIT, Leopoldshafen (Germany); Paris, Alessio; Calliari, Lucia [FBK-CMM, Trento (Italy); Verbitskiy, Nikolay [MSU, Moscow (Russian Federation); University of Vienna, Vienna (Austria); Wang, Ying; Irle, Stephan [Nagoya University, Nagoya (Japan); Fedorov, Alexander [IFW Dresden, Dresden (Germany); St. Petersburg University, St. Petersburg (Russian Federation); Haberer, Danny; Knupfer, Martin; Buechner, Bernd [IFW Dresden, Dresden (Germany); Oetzelt, Martin [BESSY II, Berlin (Germany); Petaccia, Luca [Elettra, Trieste (Italy); Usachov, Dmitry [St. Petersburg University, St. Petersburg (Russian Federation); Vyalikh, Denis [St. Petersburg University, St. Petersburg (Russian Federation); TU Dresden, Dresden (Germany); Sagdev, Hermann [MPI fuer Polymerforschung, Mainz (Germany); Yashina, Lada [MSU, Moscow (Russian Federation); Grueneis, Alexander [IFW Dresden, Dresden (Germany); University of Vienna, Vienna (Austria)

    2013-07-01

    The kinetics of the hydrogenation/deuteration reaction of graphene was studied by time-dependent x-ray photoemission spectroscopy (XPS). The graphene layer was then exposed to hydrogen or deuterium atomic gas beams, obtained by thermal cracking in a tungsten capillary at T=3000 K. After each step XPS of the C1s line was performed in order to measure H/C and D/C ratios. We have observed a strong kinetic isotope effect for the hydrogenation/deuteration reaction leading to substantially faster adsorption and higher maximum D/C ratios as compared to H/C (D/C 35% vs. H/C 25%).

  13. Vlasov simulations of Kinetic Alfven Waves at proton kinetic scales

    NARCIS (Netherlands)

    C.L. Vasconez; F. Valentini (Francesco); E. Camporeale (Enrico); P. Veltri

    2014-01-01

    htmlabstractKinetic Alfv ́en waves represent an important subject in space plasma physics, since they are thought to play a crucial role in the development of the turbulent energy cascade in the solar wind plasma at short wavelengths (of the order of the proton inertial length d p and beyond). A

  14. Physics of muscle contraction

    Science.gov (United States)

    Caruel, M.; Truskinovsky, L.

    2018-03-01

    In this paper we report, clarify and broaden various recent efforts to complement the chemistry-centered models of force generation in (skeletal) muscles by mechanics-centered models. The physical mechanisms of interest can be grouped into two classes: passive and active. The main passive effect is the fast force recovery which does not require the detachment of myosin cross-bridges from actin filaments and can operate without a specialized supply of metabolic fuel (ATP). In mechanical terms, it can be viewed as a collective folding-unfolding phenomenon in the system of interacting bi-stable units and modeled by near equilibrium Langevin dynamics. The active force generation mechanism operates at slow time scales, requires detachment and is crucially dependent on ATP hydrolysis. The underlying mechanical processes take place far from equilibrium and are represented by stochastic models with broken time reversal symmetry implying non-potentiality, correlated noise or multiple reservoirs. The modeling approaches reviewed in this paper deal with both active and passive processes and support from the mechanical perspective the biological point of view that phenomena involved in slow (active) and fast (passive) force generation are tightly intertwined. They reveal, however, that biochemical studies in solution, macroscopic physiological measurements and structural analysis do not provide by themselves all the necessary insights into the functioning of the organized contractile system. In particular, the reviewed body of work emphasizes the important role of long-range interactions and criticality in securing the targeted mechanical response in the physiological regime of isometric contractions. The importance of the purely mechanical micro-scale modeling is accentuated at the end of the paper where we address the puzzling issue of the stability of muscle response on the so called ‘descending limb’ of the isometric tetanus.

  15. Physics of muscle contraction.

    Science.gov (United States)

    Caruel, M; Truskinovsky, L

    2018-03-01

    In this paper we report, clarify and broaden various recent efforts to complement the chemistry-centered models of force generation in (skeletal) muscles by mechanics-centered models. The physical mechanisms of interest can be grouped into two classes: passive and active. The main passive effect is the fast force recovery which does not require the detachment of myosin cross-bridges from actin filaments and can operate without a specialized supply of metabolic fuel (ATP). In mechanical terms, it can be viewed as a collective folding-unfolding phenomenon in the system of interacting bi-stable units and modeled by near equilibrium Langevin dynamics. The active force generation mechanism operates at slow time scales, requires detachment and is crucially dependent on ATP hydrolysis. The underlying mechanical processes take place far from equilibrium and are represented by stochastic models with broken time reversal symmetry implying non-potentiality, correlated noise or multiple reservoirs. The modeling approaches reviewed in this paper deal with both active and passive processes and support from the mechanical perspective the biological point of view that phenomena involved in slow (active) and fast (passive) force generation are tightly intertwined. They reveal, however, that biochemical studies in solution, macroscopic physiological measurements and structural analysis do not provide by themselves all the necessary insights into the functioning of the organized contractile system. In particular, the reviewed body of work emphasizes the important role of long-range interactions and criticality in securing the targeted mechanical response in the physiological regime of isometric contractions. The importance of the purely mechanical micro-scale modeling is accentuated at the end of the paper where we address the puzzling issue of the stability of muscle response on the so called 'descending limb' of the isometric tetanus.

  16. Activation of selected shoulder muscles during unilateral wall and bench press tasks under submaximal isometric effort.

    Science.gov (United States)

    Tucci, Helga T; Ciol, Marcia A; de Araújo, Rodrigo C; de Andrade, Rodrigo; Martins, Jaqueline; McQuade, Kevin J; Oliveira, Anamaria S

    2011-07-01

    Controlled laboratory study. To assess the activation of 7 shoulder muscles under 2 closed kinetic chain (CKC) tasks for the upper extremity using submaximal isometric effort, thus providing relative quantification of muscular isometric effort for these muscles across the CKC exercises, which may be applied to rehabilitation protocols for individuals with shoulder weakness. CKC exercises favor joint congruence, reduce shear load, and promote joint dynamic stability. Additionally, knowledge about glenohumeral and periscapular muscle activity elicited during CKC exercises may help clinicians to design protocols for shoulder rehabilitation. Using surface electromyography, activation level was measured across 7 shoulder muscles in 20 healthy males, during the performance of a submaximal isometric wall press and bench press. Signals were normalized to the maximal voluntary isometric contraction, and, using paired t tests, data were analyzed between the exercises for each muscle. Compared to the wall press, the bench press elicited higher activity for most muscles, except for the upper trapezius. Levels of activity were usually low but were above 20% maximal voluntary isometric contraction for the serratus anterior on both tasks, and for the long head triceps brachii on the bench press. Both the bench press and wall press, as performed in this study, led to relatively low EMG activation levels for the muscles measured and may be considered for use in the early phases of rehabilitation.

  17. Muscle activation timing and balance response in chronic lower back pain patients with associated radiculopathy.

    Science.gov (United States)

    Frost, Lydia R; Brown, Stephen H M

    2016-02-01

    Patients with chronic low back pain and associated radiculopathy present with neuromuscular symptoms both in their lower back and down their leg; however, investigations of muscle activation have so far been isolated to the lower back. During balance perturbations, it is necessary that lower limb muscles activate with proper timing and sequencing along with the lower back musculature to efficiently regain balance control. Patients with chronic low back pain and radiculopathy and matched controls completed a series of balance perturbations (rapid bilateral arm raise, unanticipated and anticipated sudden loading, and rapid rise to toe). Muscle activation timing and sequencing as well as kinetic response to the perturbations were analyzed. Patients had significantly delayed lower limb muscle activation in rapid arm raise trials as compared to controls. In sudden loading trials, muscle activation timing was not delayed in patients; however, some differences in posterior chain muscle activation sequencing were present. Patients demonstrated less anterior-posterior movement in unanticipated sudden loading trials, and greater medial-lateral movement in rise to toe trials. Patients with low back pain and radiculopathy demonstrated some significant differences from control participants in terms of muscle activation timing, sequencing, and overall balance control. The presence of differences between patients and controls, specifically in the lower limb, indicates that radiculopathy may play a role in altering balance control in these patients. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. L-Arginine Affects Aerobic Capacity and Muscle Metabolism in MELAS (Mitochondrial Encephalomyopathy, Lactic Acidosis and Stroke-Like Episodes Syndrome.

    Directory of Open Access Journals (Sweden)

    Lance H Rodan

    Full Text Available To study the effects of L-arginine (L-Arg on total body aerobic capacity and muscle metabolism as assessed by (31Phosphorus Magnetic Resonance Spectroscopy ((31P-MRS in patients with MELAS (Mitochondrial Encephalomyopathy with Lactic Acidosis and Stroke-like episodes syndrome.We performed a case control study in 3 MELAS siblings (m.3243A>G tRNA(leu(UUR in MTTL1 gene with different % blood mutant mtDNA to evaluate total body maximal aerobic capacity (VO(2peak using graded cycle ergometry and muscle metabolism using 31P-MRS. We then ran a clinical trial pilot study in MELAS sibs to assess response of these parameters to single dose and a 6-week steady-state trial of oral L-Arginine.At baseline (no L-Arg, MELAS had lower serum Arg (p = 0.001. On 3(1P-MRS muscle at rest, MELAS subjects had increased phosphocreatine (PCr (p = 0.05, decreased ATP (p = 0.018, and decreased intracellular Mg(2+ (p = 0.0002 when compared to matched controls. With L-arginine therapy, the following trends were noted in MELAS siblings on cycle ergometry: (1 increase in mean % maximum work at anaerobic threshold (AT (2 increase in % maximum heart rate at AT (3 small increase in VO(2peak. On (31P-MRS the following mean trends were noted: (1 A blunted decrease in pH after exercise (less acidosis (2 increase in Pi/PCr ratio (ADP suggesting increased work capacity (3 a faster half time of PCr recovery (marker of mitochondrial activity following 5 minutes of moderate intensity exercise (4 increase in torque.These results suggest an improvement in aerobic capacity and muscle metabolism in MELAS subjects in response to supplementation with L-Arg. Intramyocellular hypomagnesemia is a novel finding that warrants further study.Class III evidence that L-arginine improves aerobic capacity and muscle metabolism in MELAS subjects.ClinicalTrials.gov NCT01603446.

  19. L-Arginine Affects Aerobic Capacity and Muscle Metabolism in MELAS (Mitochondrial Encephalomyopathy, Lactic Acidosis and Stroke-Like Episodes) Syndrome.

    Science.gov (United States)

    Rodan, Lance H; Wells, Greg D; Banks, Laura; Thompson, Sara; Schneiderman, Jane E; Tein, Ingrid

    2015-01-01

    To study the effects of L-arginine (L-Arg) on total body aerobic capacity and muscle metabolism as assessed by (31)Phosphorus Magnetic Resonance Spectroscopy ((31)P-MRS) in patients with MELAS (Mitochondrial Encephalomyopathy with Lactic Acidosis and Stroke-like episodes) syndrome. We performed a case control study in 3 MELAS siblings (m.3243A>G tRNA(leu(UUR)) in MTTL1 gene) with different % blood mutant mtDNA to evaluate total body maximal aerobic capacity (VO(2peak)) using graded cycle ergometry and muscle metabolism using 31P-MRS. We then ran a clinical trial pilot study in MELAS sibs to assess response of these parameters to single dose and a 6-week steady-state trial of oral L-Arginine. At baseline (no L-Arg), MELAS had lower serum Arg (p = 0.001). On 3(1)P-MRS muscle at rest, MELAS subjects had increased phosphocreatine (PCr) (p = 0.05), decreased ATP (p = 0.018), and decreased intracellular Mg(2+) (p = 0.0002) when compared to matched controls. With L-arginine therapy, the following trends were noted in MELAS siblings on cycle ergometry: (1) increase in mean % maximum work at anaerobic threshold (AT) (2) increase in % maximum heart rate at AT (3) small increase in VO(2peak). On (31)P-MRS the following mean trends were noted: (1) A blunted decrease in pH after exercise (less acidosis) (2) increase in Pi/PCr ratio (ADP) suggesting increased work capacity (3) a faster half time of PCr recovery (marker of mitochondrial activity) following 5 minutes of moderate intensity exercise (4) increase in torque. These results suggest an improvement in aerobic capacity and muscle metabolism in MELAS subjects in response to supplementation with L-Arg. Intramyocellular hypomagnesemia is a novel finding that warrants further study. Class III evidence that L-arginine improves aerobic capacity and muscle metabolism in MELAS subjects. ClinicalTrials.gov NCT01603446.

  20. Stretching skeletal muscle: chronic muscle lengthening through sarcomerogenesis.

    Directory of Open Access Journals (Sweden)

    Alexander M Zöllner

    Full Text Available Skeletal muscle responds to passive overstretch through sarcomerogenesis, the creation and serial deposition of new sarcomere units. Sarcomerogenesis is critical to muscle function: It gradually re-positions the muscle back into its optimal operating regime. Animal models of immobilization, limb lengthening, and tendon transfer have provided significant insight into muscle adaptation in vivo. Yet, to date, there is no mathematical model that allows us to predict how skeletal muscle adapts to mechanical stretch in silico. Here we propose a novel mechanistic model for chronic longitudinal muscle growth in response to passive mechanical stretch. We characterize growth through a single scalar-valued internal variable, the serial sarcomere number. Sarcomerogenesis, the evolution of this variable, is driven by the elastic mechanical stretch. To analyze realistic three-dimensional muscle geometries, we embed our model into a nonlinear finite element framework. In a chronic limb lengthening study with a muscle stretch of 1.14, the model predicts an acute sarcomere lengthening from 3.09[Formula: see text]m to 3.51[Formula: see text]m, and a chronic gradual return to the initial sarcomere length within two weeks. Compared to the experiment, the acute model error was 0.00% by design of the model; the chronic model error was 2.13%, which lies within the rage of the experimental standard deviation. Our model explains, from a mechanistic point of view, why gradual multi-step muscle lengthening is less invasive than single-step lengthening. It also explains regional variations in sarcomere length, shorter close to and longer away from the muscle-tendon interface. Once calibrated with a richer data set, our model may help surgeons to prevent muscle overstretch and make informed decisions about optimal stretch increments, stretch timing, and stretch amplitudes. We anticipate our study to open new avenues in orthopedic and reconstructive surgery and enhance

  1. Experimental muscle pain during a forward lunge--the effects on knee joint dynamics and electromyographic activity

    DEFF Research Database (Denmark)

    Henriksen, Marius; Alkjaer, T; Simonsen, Erik Bruun

    2009-01-01

    . Isotonic saline (0.9%) was used as control. MAIN OUTCOME MEASUREMENTS: Three-dimensional movement analyses were performed and inverse dynamics were used to calculate joint kinematics and kinetics for ankle, knee and hip joints. Electromyographic (EMG) signals of the hamstrings and quadriceps muscles were...

  2. Muscle performance after the menopause.

    Science.gov (United States)

    Sirola, Joonas; Rikkonen, Toni

    2005-06-01

    The timing of the menopause transition has remained fairly constant throughout history. It represents a milestone in female health and, after passing through it, women experience increased musculoskeletal and cardiovascular morbidity. Muscle performance is an important determinant of functional capacity and quality of life among the elderly and is also involved in the maintenance of balance. Therefore, good muscle strength can prevent fragility fractures and lessen the burden of osteoporosis. Muscle strength begins to decline during the perimenopausal years and this phenomenon seems to be partly estrogen dependent. Randomized controlled trials have indicated that hormone replacement therapy may prevent a decline in muscle performance, although the exact mechanism of estrogen-dependent sarcopenia remains to be clarified. Exercises have been shown to improve postmenopausal muscle performance and hormone replacement therapy may also potentiate these beneficial effects. Improvement or maintenance of muscle strength alone, however, may not be considered as a primary indication for long-term hormone replacement therapy in view of current knowledge of its risks and benefits. Work history and educational background may be associated with postmenopausal muscle performance, which itself has unique associations with skeletal and cardiovascular diseases.

  3. Overview of the Muscle Cytoskeleton

    Science.gov (United States)

    Henderson, Christine A.; Gomez, Christopher G.; Novak, Stefanie M.; Mi-Mi, Lei; Gregorio, Carol C.

    2018-01-01

    Cardiac and skeletal striated muscles are intricately designed machines responsible for muscle contraction. Coordination of the basic contractile unit, the sarcomere, and the complex cytoskeletal networks are critical for contractile activity. The sarcomere is comprised of precisely organized individual filament systems that include thin (actin), thick (myosin), titin, and nebulin. Connecting the sarcomere to other organelles (e.g., mitochondria and nucleus) and serving as the scaffold to maintain cellular integrity are the intermediate filaments. The costamere, on the other hand, tethers the sarcomere to the cell membrane. Unique structures like the intercalated disc in cardiac muscle and the myotendinous junction in skeletal muscle help synchronize and transmit force. Intense investigation has been done on many of the proteins that make up these cytoskeletal assemblies. Yet the details of their function and how they interconnect have just started to be elucidated. A vast number of human myopathies are contributed to mutations in muscle proteins; thus understanding their basic function provides a mechanistic understanding of muscle disorders. In this review, we highlight the components of striated muscle with respect to their interactions, signaling pathways, functions, and connections to disease. PMID:28640448

  4. Muscle channelopathies and electrophysiological approach

    Directory of Open Access Journals (Sweden)

    Cherian Ajith

    2008-01-01

    Full Text Available Myotonic syndromes and periodic paralyses are rare disorders of skeletal muscle characterized mainly by muscle stiffness or episodic attacks of weakness. Familial forms are caused by mutation in genes coding for skeletal muscle voltage ionic channels. Familial periodic paralysis and nondystrophic myotonias are disorders of skeletal muscle excitability caused by mutations in genes coding for voltage-gated ion channels. These diseases are characterized by episodic failure of motor activity due to muscle weakness (paralysis or stiffness (myotonia. Clinical studies have identified two forms of periodic paralyses: hypokalemic periodic paralysis (hypoKPP and hyperkalemic periodic paralysis (hyperKPP, based on changes in serum potassium levels during the attacks, and three distinct forms of myotonias: paramyotonia congenita (PC, potassium-aggravated myotonia (PAM, and myotonia congenita (MC. PC and PAM have been linked to missense mutations in the SCN4A gene, which encodes α subunit of the voltage-gated sodium channel, whereas MC is caused by mutations in the chloride channel gene (CLCN1. Exercise is known to trigger, aggravate, or relieve symptoms. Therefore, exercise can be used as a functional test in electromyography to improve the diagnosis of these muscle disorders. Abnormal changes in the compound muscle action potential can be disclosed using different exercise tests. Five electromyographic (EMG patterns (I-V that may be used in clinical practice as guides for molecular diagnosis are discussed.

  5. Immunology Guides Skeletal Muscle Regeneration

    Directory of Open Access Journals (Sweden)

    F. Andrea Sass

    2018-03-01

    Full Text Available Soft tissue trauma of skeletal muscle is one of the most common side effects in surgery. Muscle injuries are not only caused by accident-related injuries but can also be of an iatrogenic nature as they occur during surgical interventions when the anatomical region of interest is exposed. If the extent of trauma surpasses the intrinsic regenerative capacities, signs of fatty degeneration and formation of fibrotic scar tissue can occur, and, consequentially, muscle function deteriorates or is diminished. Despite research efforts to investigate the physiological healing cascade following trauma, our understanding of the early onset of healing and how it potentially determines success or failure is still only fragmentary. This review focuses on the initial physiological pathways following skeletal muscle trauma in comparison to bone and tendon trauma and what conclusions can be drawn from new scientific insights for the development of novel therapeutic strategies. Strategies to support regeneration of muscle tissue after injury are scarce, even though muscle trauma has a high incidence. Based on tissue specific differences, possible clinical treatment options such as local immune-modulatory and cell therapeutic approaches are suggested that aim to support the endogenous regenerative potential of injured muscle tissues.

  6. The effects of weighted skates on ice-skating kinematics, kinetics and muscular activity.

    Science.gov (United States)

    Mavor, Matthew P; Hay, Dean C; Graham, Ryan B

    2018-07-01

    Sport-specific resistance training, through limb loading, can be a complimentary training method to traditional resistance training by loading the working muscles during all phases of a specific movement. The purpose of this study was to examine the acute effects of skating with an additional load on the skate, using a skate weight prototype, on kinematics, kinetics, and muscle activation during the acceleration phase while skating on a synthetic ice surface. 10 male hockey skaters accelerated from rest (standing erect with knees slightly bent) under four non-randomized load conditions: baseline 1 (no weight), light (0.9 kg per skate), heavy (1.8 kg per skate), and baseline 2 (no weight). Skating with additional weight caused athletes to skate slower (p skates decreased skating velocity, but athletes maintained similar muscle activation profiles (magnitude and trends) with minor changes to their skating kinematics.

  7. Effect of exogenous CNT on kinetics of 3H-lysine in haerbin white rabbits

    International Nuclear Information System (INIS)

    Liu Dengke; Zan Linsen; Liu Yongfeng

    2007-01-01

    Haerbin White rabbits was used as testimonial and trace kinetics and radioimmunoassay and other techniques were used to study the distribution, transportation and metabolism of 3 H-Lysine in the animal. The metabolic kinetics of 3 H-Lysine could be described by the follows equation: (Y-circumflex) (t) =983.6281e -0.021935t + 1773.9999e -0.083932t - 983.6281e -0.432590t - 0773.9999e -0.050399t + 300.2820. Experimental results showed that 3 H-Lysine was accumulated mainly in kidney, heart, liver, spleen and muscle in check group; accumulated mainly in muscle, stomach, liver, heart and genitalia in cAMP treated group; accumulated in bladder, muscle, lung and intestine in cGMP treated group; and accumulated mainly in muscle, bladder, genitalia an fat in cAMP + cGMP treated group, respectively. The distribution of 3 H-Lysine was of evidently variations being treated with exogenous CNT. The results indicated that the distribution, transportation and metabolism of 3 H-Lysine were significantly affected by exogenous CNT in the Haerbin White rabbit. (authors)

  8. Alternative S2 Hinge Regions of the Myosin Rod Affect Myofibrillar Structure and Myosin Kinetics

    Energy Technology Data Exchange (ETDEWEB)

    Miller, Mark S.; Dambacher, Corey M.; Knowles, Aileen F.; Braddock, Joan M.; Farman, Gerrie P.; Irving, Thomas C.; Swank, Douglas M.; Bernstein, Sanford I.; Maughan, David W.; (RPI); (IIT); (SDSU); (Vermont)

    2009-07-01

    The subfragment 2/light meromyosin 'hinge' region has been proposed to significantly contribute to muscle contraction force and/or speed. Transgenic replacement of the endogenous fast muscle isovariant hinge A (exon 15a) in Drosophila melanogaster indirect flight muscle with the slow muscle hinge B (exon 15b) allows examination of the structural and functional changes when only this region of the myosin molecule is different. Hinge B was previously shown to increase myosin rod length, increase A-band and sarcomere length, and decrease flight performance compared to hinge A. We applied additional measures to these transgenic lines to further evaluate the consequences of modifying this hinge region. Structurally, the longer A-band and sarcomere lengths found in the hinge B myofibrils appear to be due to the longitudinal addition of myosin heads. Functionally, hinge B, although a significant distance from the myosin catalytic domain, alters myosin kinetics in a manner consistent with this region increasing myosin rod length. These structural and functional changes combine to decrease whole fly wing-beat frequency and flight performance. Our results indicate that this hinge region plays an important role in determining myosin kinetics and in regulating thick and thin filament lengths as well as sarcomere length.

  9. Elements of plasma kinetic theory

    International Nuclear Information System (INIS)

    Guasp, J.

    1976-01-01

    The physical foundations of plasma kinetic equations are exposed inside a series of seminars on plasma and fusion physics. The Vlasov and collisional equations with its application range have been discussed. The momenta equations for the macroscopic magnitudes and the more usual approximations have been obtained: two fluid equations for cold and warm plasmas, magnetohydrodynamic equations and the double-adiabatic theory. (author)

  10. Kinetic studies on leucite precursors

    Czech Academy of Sciences Publication Activity Database

    Mrázová, M.; Kloužková, A.; Kohoutková, Martina

    2009-01-01

    Roč. 7, č. 2 (2009), s. 205-210 ISSN 1895-1066 R&D Projects: GA MPO 2A-1TP1/063 Institutional research plan: CEZ:AV0Z40320502 Keywords : leucite * crystallization kinetics * hydrothermal Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 1.065, year: 2009

  11. Solving Simple Kinetics without Integrals

    Science.gov (United States)

    de la Pen~a, Lisandro Herna´ndez

    2016-01-01

    The solution of simple kinetic equations is analyzed without referencing any topic from differential equations or integral calculus. Guided by the physical meaning of the rate equation, a systematic procedure is used to generate an approximate solution that converges uniformly to the exact solution in the case of zero, first, and second order…

  12. Robustness Analysis of Kinetic Structures

    DEFF Research Database (Denmark)

    Kirkegaard, Poul Henning; Sørensen, John Dalsgaard

    2009-01-01

    Kinetic structures in architecture follows a new trend which is emerging in responsive architecture coined by Nicholas Negroponte when he proposed that architecture may benefit from the integration of computing power into built spaces and structures, and that better performing, more rational...

  13. Kinetics of Bio-Reactions

    DEFF Research Database (Denmark)

    Villadsen, John

    2015-01-01

    his chapter predicts the specific rates of reaction by means of a mathematical expression, the kinetics of the reaction. This expression can be derived through a mechanistic interpretation of an enzymatically catalyzed reaction, but it is essentially of empirical nature for cell reactions. The mo...

  14. Resonance transport and kinetic entropy

    International Nuclear Information System (INIS)

    Ivanov, Yu.B.; Knoll, J.; Voskresensky, D.N.

    2000-01-01

    We continue the description of the dynamics of unstable particles within the real-time formulation of nonequilibrium field theory initiated in a previous paper . There we suggest to use Baym's PHI-functional method in order to achieve approximation schemes with 'built in' consistency with respect to conservation laws and thermodynamics even in the case of particles with finite damping width. Starting from Kadanoff-Baym equations we discuss a consistent first order gradient approach to transport which preserves the PHI-derivable properties. The validity conditions for the resulting quantum four-phase-space kinetic theory are discussed under the perspective to treat particles with broad damping widths. This non-equilibrium dynamics naturally includes all those quantum features already inherent in the corresponding equilibrium limit (e.g. Matsubara formalism) at the same level of PHI-derivable approximation. Various collision-term diagrams are discussed including those of higher order which lead to memory effects. As an important novel part we derive a generalized nonequilibrium expression for the kinetic entropy flow, which includes contributions from fluctuations and mass-width effects. In special cases an H-theorem is derived implying that the entropy can only increase with time. Memory effects in the kinetic terms provide contributions to the kinetic entropy flow that in the equilibrium limit recover the famous bosonic type T 3 lnT correction to the specific heat in the case of Fermi liquids like Helium-3

  15. Skeletal muscle performance and ageing.

    Science.gov (United States)

    Tieland, Michael; Trouwborst, Inez; Clark, Brian C

    2018-02-01

    The world population is ageing rapidly. As society ages, the incidence of physical limitations is dramatically increasing, which reduces the quality of life and increases healthcare expenditures. In western society, ~30% of the population over 55 years is confronted with moderate or severe physical limitations. These physical limitations increase the risk of falls, institutionalization, co-morbidity, and premature death. An important cause of physical limitations is the age-related loss of skeletal muscle mass, also referred to as sarcopenia. Emerging evidence, however, clearly shows that the decline in skeletal muscle mass is not the sole contributor to the decline in physical performance. For instance, the loss of muscle strength is also a strong contributor to reduced physical performance in the elderly. In addition, there is ample data to suggest that motor coordination, excitation-contraction coupling, skeletal integrity, and other factors related to the nervous, muscular, and skeletal systems are critically important for physical performance in the elderly. To better understand the loss of skeletal muscle performance with ageing, we aim to provide a broad overview on the underlying mechanisms associated with elderly skeletal muscle performance. We start with a system level discussion and continue with a discussion on the influence of lifestyle, biological, and psychosocial factors on elderly skeletal muscle performance. Developing a broad understanding of the many factors affecting elderly skeletal muscle performance has major implications for scientists, clinicians, and health professionals who are developing therapeutic interventions aiming to enhance muscle function and/or prevent mobility and physical limitations and, as such, support healthy ageing. © 2017 The Authors. Journal of Cachexia, Sarcopenia and Muscle published by John Wiley & Sons Ltd on behalf of the Society on Sarcopenia, Cachexia and Wasting Disorders.

  16. Bigorexia: bodybuilding and muscle dysmorphia.

    Science.gov (United States)

    Mosley, Philip E

    2009-05-01

    Muscle dysmorphia is an emerging condition that primarily affects male bodybuilders. Such individuals obsess about being inadequately muscular. Compulsions include spending hours in the gym, squandering excessive amounts of money on ineffectual sports supplements, abnormal eating patterns or even substance abuse. In this essay, I illustrate the features of muscle dysmorphia by employing the first-person account of a male bodybuilder afflicted by this condition. I briefly outline the history of bodybuilding and examine whether the growth of this sport is linked to a growing concern with body image amongst males. I suggest that muscle dysmorphia may be a new expression of a common pathology shared with the eating disorders.

  17. Diabetic muscle infarction: radiologic evaluation

    International Nuclear Information System (INIS)

    Chason, D.P.; Fleckenstein, J.L.; Burns, D.K.; Rojas, G.

    1996-01-01

    Four patients with severe diabetes mellitus presenting with acute thigh pain, tenderness, and swelling were evaluated by imaging techniques and biopsy. Edema in the affected muscles was seen in two patients with MRI studies. Femoral artery calcification and mild muscle swelling was present in one patient who underwent CT. Decreased echogenicity was seen in the involved muscle in a patient studied with ultrasound. Serum enzymes were normal or mildly elevated in three patients (not reported in one). Biopsy demonstrated necrosis and regenerative change in all cases. MRI, although nonspecific, is the best imaging technique to suggest the diagnosis of DMI in the appropriate clinical setting, thereby obviating biopsy. (orig./MG)

  18. Skeletal Muscle Na+ Channel Disorders

    Directory of Open Access Journals (Sweden)

    Dina eSimkin

    2011-10-01

    Full Text Available Five inherited human disorders affecting skeletal muscle contraction have been traced to mutations in the gene encoding the voltage-gated sodium channel Nav1.4. The main symptoms of these disorders are myotonia or periodic paralysis caused by changes in skeletal muscle fiber excitability. Symptoms of these disorders vary from mild or latent disease to incapacitating or even death in severe cases. As new human sodium channel mutations corresponding to disease states become discovered, the importance of understanding the role of the sodium channel in skeletal muscle function and disease state grows.

  19. Activation of respiratory muscles during respiratory muscle training.

    Science.gov (United States)

    Walterspacher, Stephan; Pietsch, Fabian; Walker, David Johannes; Röcker, Kai; Kabitz, Hans-Joachim

    2018-01-01

    It is unknown which respiratory muscles are mainly activated by respiratory muscle training. This study evaluated Inspiratory Pressure Threshold Loading (IPTL), Inspiratory Flow Resistive Loading (IFRL) and Voluntary Isocapnic Hyperpnea (VIH) with regard to electromyographic (EMG) activation of the sternocleidomastoid muscle (SCM), parasternal muscles (PARA) and the diaphragm (DIA) in randomized order. Surface EMG were analyzed at the end of each training session and normalized using the peak EMG recorded during maximum inspiratory maneuvers (Sniff nasal pressure: SnPna, maximal inspiratory mouth occlusion pressure: PImax). 41 healthy participants were included. Maximal activation was achieved for SCM by SnPna; the PImax activated predominantly PARA and DIA. Activations of SCM and PARA were higher in IPTL and VIH than for IFRL (p<0.05). DIA was higher applying IPTL compared to IFRL or VIH (p<0.05). IPTL, IFRL and VIH differ in activation of inspiratory respiratory muscles. Whereas all methods mainly stimulate accessory respiratory muscles, diaphragm activation was predominant in IPTL. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Eccentric muscle challenge shows osteopontin polymorphism modulation of muscle damage.

    Science.gov (United States)

    Barfield, Whitney L; Uaesoontrachoon, Kitipong; Wu, Chung-Sheih; Lin, Stephen; Chen, Yue; Wang, Paul C; Kanaan, Yasmine; Bond, Vernon; Hoffman, Eric P

    2014-08-01

    A promoter polymorphism of the osteopontin (OPN) gene (rs28357094) has been associated with multiple inflammatory states, severity of Duchenne muscular dystrophy (DMD) and muscle size in healthy young adults. We sought to define the mechanism of action of the polymorphism, using allele-specific in vitro reporter assays in muscle cells, and a genotype-stratified intervention in healthy controls. In vitro reporter constructs showed the G allele to respond to estrogen treatment, whereas the T allele showed no transcriptional response. Young adult volunteers (n = 187) were enrolled into a baseline study, and subjects with specific rs28357094 genotypes enrolled into an eccentric muscle challenge intervention [n = 3 TT; n = 3 GG/GT (dominant inheritance model)]. Female volunteers carrying the G allele showed significantly greater inflammation and increased muscle volume change as determined by magnetic resonance imaging T1- and T2-weighted images after eccentric challenge, as well as greater decrement in biceps muscle force. Our data suggest a model where the G allele enables enhanced activities of upstream enhancer elements due to loss of Sp1 binding at the polymorphic site. This results in significantly greater expression of the pro-inflammatory OPN cytokine during tissue remodeling in response to challenge in G allele carriers, promoting muscle hypertrophy in normal females, but increased damage in DMD patients. © The Author 2014. Published by Oxford University Press.

  1. Chronic clenbuterol treatment compromises force production without directly altering skeletal muscle contractile machinery

    Science.gov (United States)

    Py, G; Ramonatxo, C; Sirvent, P; Sanchez, A M J; Philippe, A G; Douillard, A; Galbès, O; Lionne, C; Bonnieu, A; Chopard, A; Cazorla, O; Lacampagne, A; Candau, R B

    2015-01-01

    Clenbuterol is a β2-adrenergic receptor agonist known to induce skeletal muscle hypertrophy and a slow-to-fast phenotypic shift. The aim of the present study was to test the effects of chronic clenbuterol treatment on contractile efficiency and explore the underlying mechanisms, i.e. the muscle contractile machinery and calcium-handling ability. Forty-three 6-week-old male Wistar rats were randomly allocated to one of six groups that were treated with either subcutaneous equimolar doses of clenbuterol (4 mg kg−1 day−1) or saline solution for 9, 14 or 21 days. In addition to the muscle hypertrophy, although an 89% increase in absolute maximal tetanic force (Po) was noted, specific maximal tetanic force (sPo) was unchanged or even depressed in the slow twitch muscle of the clenbuterol-treated rats (P muscle contraction and relaxation force kinetics indicated that clenbuterol treatment significantly reduced the rate constant of force development and the slow and fast rate constants of relaxation in extensor digitorum longus muscle (P fast rate constant of relaxation in soleus muscle (P fibres (fast twitch fibres) from clenbuterol-treated animals demonstrated decreased amplitude after 14 days (−19%, P < 0.01) and 21 days (−25%, P < 0.01). In conclusion, we showed that chronic clenbuterol treatment reduces contractile efficiency, with altered contraction and relaxation kinetics, but without directly altering the contractile machinery. Lower Ca2+ release during contraction could partially explain these deleterious effects. PMID:25656230

  2. Ethanol Exposure Causes Muscle Degeneration in Zebrafish

    Directory of Open Access Journals (Sweden)

    Elizabeth C. Coffey

    2018-03-01

    Full Text Available Alcoholic myopathies are characterized by neuromusculoskeletal symptoms such as compromised movement and weakness. Although these symptoms have been attributed to neurological damage, EtOH may also target skeletal muscle. EtOH exposure during zebrafish primary muscle development or adulthood results in smaller muscle fibers. However, the effects of EtOH exposure on skeletal muscle during the growth period that follows primary muscle development are not well understood. We determined the effects of EtOH exposure on muscle during this phase of development. Strikingly, muscle fibers at this stage are acutely sensitive to EtOH treatment: EtOH induces muscle degeneration. The severity of EtOH-induced muscle damage varies but muscle becomes more refractory to EtOH as muscle develops. NF-kB induction in muscle indicates that EtOH triggers a pro-inflammatory response. EtOH-induced muscle damage is p53-independent. Uptake of Evans blue dye shows that EtOH treatment causes sarcolemmal instability before muscle fiber detachment. Dystrophin-null sapje mutant zebrafish also exhibit sarcolemmal instability. We tested whether Trichostatin A (TSA, which reduces muscle degeneration in sapje mutants, would affect EtOH-treated zebrafish. We found that TSA and EtOH are a lethal combination. EtOH does, however, exacerbate muscle degeneration in sapje mutants. EtOH also disrupts adhesion of muscle fibers to their extracellular matrix at the myotendinous junction: some detached muscle fibers retain beta-Dystroglycan indicating failure of muscle end attachments. Overexpression of Paxillin, which reduces muscle degeneration in zebrafish deficient for beta-Dystroglycan, is not sufficient to rescue degeneration. Taken together, our results suggest that EtOH exposure has pleiotropic deleterious effects on skeletal muscle.

  3. Some Aspects of Extended Kinetic Equation

    Directory of Open Access Journals (Sweden)

    Dilip Kumar

    2015-09-01

    Full Text Available Motivated by the pathway model of Mathai introduced in 2005 [Linear Algebra and Its Applications, 396, 317–328] we extend the standard kinetic equations. Connection of the extended kinetic equation with fractional calculus operator is established. The solution of the general form of the fractional kinetic equation is obtained through Laplace transform. The results for the standard kinetic equation are obtained as the limiting case.

  4. Holographic kinetic k-essence model

    Energy Technology Data Exchange (ETDEWEB)

    Cruz, Norman [Departamento de Fisica, Facultad de Ciencia, Universidad de Santiago de Chile, Casilla 307, Santiago (Chile)], E-mail: ncruz@lauca.usach.cl; Gonzalez-Diaz, Pedro F.; Rozas-Fernandez, Alberto [Colina de los Chopos, Instituto de Fisica Fundamental, Consejo Superior de Investigaciones Cientificas, Serrano 121, 28006 Madrid (Spain)], E-mail: a.rozas@cfmac.csic.es; Sanchez, Guillermo [Departamento de Matematica y Ciencia de la Computacion, Facultad de Ciencia, Universidad de Santiago de Chile, Casilla 307, Santiago (Chile)], E-mail: gsanchez@usach.cl

    2009-08-31

    We consider a connection between the holographic dark energy density and the kinetic k-essence energy density in a flat FRW universe. With the choice c{>=}1, the holographic dark energy can be described by a kinetic k-essence scalar field in a certain way. In this Letter we show this kinetic k-essential description of the holographic dark energy with c{>=}1 and reconstruct the kinetic k-essence function F(X)

  5. Knitting and weaving artificial muscles.

    Science.gov (United States)

    Maziz, Ali; Concas, Alessandro; Khaldi, Alexandre; Stålhand, Jonas; Persson, Nils-Krister; Jager, Edwin W H

    2017-01-01

    A need exists for artificial muscles that are silent, soft, and compliant, with performance characteristics similar to those of skeletal muscle, enabling natural interaction of assistive devices with humans. By combining one of humankind's oldest technologies, textile processing, with electroactive polymers, we demonstrate here the feasibility of wearable, soft artificial muscles made by weaving and knitting, with tunable force and strain. These textile actuators were produced from cellulose yarns assembled into fabrics and coated with conducting polymers using a metal-free deposition. To increase the output force, we assembled yarns in parallel by weaving. The force scaled linearly with the number of yarns in the woven fabric. To amplify the strain, we knitted a stretchable fabric, exhibiting a 53-fold increase in strain. In addition, the textile construction added mechanical stability to the actuators. Textile processing permits scalable and rational production of wearable artificial muscles, and enables novel ways to design assistive devices.

  6. Simvastatin effects on skeletal muscle

    DEFF Research Database (Denmark)

    Larsen, Steen; Stride, Nis; Hey-Mogensen, Martin

    2013-01-01

    Glucose tolerance and skeletal muscle coenzyme Q(10) (Q(10)) content, mitochondrial density, and mitochondrial oxidative phosphorylation (OXPHOS) capacity were measured in simvastatin-treated patients (n = 10) and in well-matched control subjects (n = 9)....

  7. Muscle glycogen stores and fatigue

    DEFF Research Database (Denmark)

    Ørtenblad, Niels; Westerblad, Håkan; Nielsen, Joachim

    2013-01-01

      Studies performed at the beginning of the last century revealed the importance of carbohydrate as a fuel during exercise, and the importance of muscle glycogen on performance has subsequently been confirmed in numerous studies. However, the link between glycogen depletion and impaired muscle...... function during fatigue is not well understood and a direct cause-and-effect relationship between glycogen and muscle function remains to be established. The use of electron microscopy has revealed that glycogen is not homogeneously distributed in skeletal muscle fibres, but rather localized in distinct...... pools. Furthermore, each glycogen granule has its own metabolic machinery with glycolytic enzymes and regulating proteins. One pool of such glycogenolytic complexes is localized within the myofibrils in close contact with key proteins involved in the excitation-contraction coupling and Ca2+ release from...

  8. Compensatory Hypertrophy of Skeletal Muscle: Contractile Characteristics

    Science.gov (United States)

    Ianuzzo, C. D.; Chen, V.

    1977-01-01

    Describes an experiment using rats that demonstrates contractile characteristics of normal and hypertrophied muscle. Compensatory hypertrophy of the plantaris muscle is induced by surgical removal of the synergistic gastrocnemium muscle. Includes methods for determination of contractile properties of normal and hypertrophied muscle and…

  9. Skeletal muscle lymphoma: observations at MR imaging

    International Nuclear Information System (INIS)

    Eustace, S.; Winalski, C.S.; McGowen, A.; Lan, H.; Dorfman, D.

    1996-01-01

    We present the MR appearances of three patients with biopsy-proven primary lymphoma of skeletal muscle. In each case lymphoma resulted in bulky expansion of the involved muscle, homogeneously isointense to skeletal muscle on T1-weighted images, homogeneously hyperintense to skeletal muscle on T2-weighted images and diffusely enhancing following intravenous administration of gadopentate dimeglumine. (orig.)

  10. Quantitative muscle ultrasonography in amyotrophic lateral sclerosis.

    NARCIS (Netherlands)

    Arts, I.M.P.; Rooij, F.G. van; Overeem, S.; Pillen, S.; Janssen, H.M.; Schelhaas, H.J.; Zwarts, M.J.

    2008-01-01

    In this study, we examined whether quantitative muscle ultrasonography can detect structural muscle changes in early-stage amyotrophic lateral sclerosis (ALS). Bilateral transverse scans were made of five muscles or muscle groups (sternocleidomastoid, biceps brachii/brachialis, forearm flexor group,

  11. Diabetic muscle infarction: atypical MR appearance

    International Nuclear Information System (INIS)

    Sharma, P.; Mangwana, S.; Kapoor, R.K.

    2000-01-01

    We describe a case of diabetic muscle infarction which had atypical features of hyperintensity of the affected muscle on T1-weighted images. Biopsy was performed which revealed diffuse extensive hemorrhage within the infarcted muscle. We believe increased signal intensity on T1-weighted images should suggest hemorrhage within the infarcted muscle. (orig.)

  12. Electrically controllable artificial PAN muscles

    Science.gov (United States)

    Salehpoor, Karim; Shahinpoor, Mohsen; Mojarrad, Mehran

    1996-02-01

    Artificial muscles made with polyacrylonitrile (PAN) fibers are traditionally activated in electrolytic solution by changing the pH of the solution by the addition of acids and/or bases. This usually consumes a considerable amount of weak acids or bases. Furthermore, the synthetic muscle (PAN) itself has to be impregnated with an acid or a base and must have an appropriate enclosure or provision for waste collection after actuation. This work introduces a method by which the PAN muscle may be elongated or contracted in an electric field. We believe this is the first time that this has been achieved with PAN fibers as artificial muscles. In this new development the PAN muscle is first put in close contact with one of the two platinum wires (electrodes) immersed in an aqueous solution of sodium chloride. Applying an electric voltage between the two wires changes the local acidity of the solution in the regions close to the platinum wires. This is because of the ionization of sodium chloride molecules and the accumulation of Na+ and Cl- ions at the negative and positive electrode sites, respectively. This ion accumulation, in turn, is accompanied by a sharp increase and decrease of the local acidity in regions close to either of the platinum wires, respectively. An artificial muscle, in close contact with the platinum wire, because of the change in the local acidity will contract or expand depending on the polarity of the electric field. This scheme allows the experimenter to use a fixed flexible container of an electrolytic solution whose local pH can be modulated by an imposed electric field while the produced ions are basically trapped to stay in the neighborhood of a given electrode. This method of artificial muscle activation has several advantages. First, the need to use a large quantity of acidic or alkaline solutions is eliminated. Second, the use of a compact PAN muscular system is facilitated for applications in active musculoskeletal structures. Third, the

  13. Kinetic modelling of enzymatic starch hydrolysis

    NARCIS (Netherlands)

    Bednarska, K.A.

    2015-01-01

    Kinetic modelling of enzymatic starch hydrolysis – a summary

    K.A. Bednarska

    The dissertation entitled ‘Kinetic modelling of enzymatic starch hydrolysis’ describes the enzymatic hydrolysis and kinetic modelling of liquefaction and saccharification of wheat starch.

  14. Evaluation of muscle hyperactivity of the grimacing muscles by unilateral tight eyelid closure and stapedius muscle tone.

    Science.gov (United States)

    Shiba, Masato; Matsuo, Kiyoshi; Ban, Ryokuya; Nagai, Fumio

    2012-10-01

    Muscle hyperactivity of grimacing muscles, including the orbicularis oculi and corrugator supercilii muscles that cause crow's feet and a glabellar frown line with ageing, cannot be accurately evaluated by surface observation. In 71 subjects, this study investigated the extent to which grimacing muscles are innervated by the bilateral motor cortices, whether the corticofacial projection to the grimacing muscles affects the facially innervated stapedius muscle tone by measuring static compliance of the tympanic membrane, and whether unilateral tight eyelid closure with contraction of the grimacing muscles changes static compliance. Unilateral tight eyelid closure and its subsequent change in the contralateral vertical medial eyebrow position revealed that motor neurons of the orbicularis oculi and corrugator supercilii muscles were innervated by the bilateral motor cortices with weak-to-strong contralateral dominance. The orbicularis oculi, corrugator supercilii, and stapedius muscles innervated by the bilateral motor cortices had increased muscle hyperactivity, which lowered the vertical medial eyebrow position and decreased the static compliance of the tympanic membrane more than those innervated by the unilateral motor cortex. Unilateral enhanced tight eyelid closure with contraction of the grimacing muscles in certain subjects ipsilaterally decreased the static compliance with increased contraction of the stapedius muscle, which probably occurs to immobilise the tympanic membrane and protect the inner ear from loud sound. Evaluation of unilateral tight eyelid closure and the subsequent change in the contralateral vertical medial eyebrow position as well as a measurement of the static compliance for the stapedius muscle tone has revealed muscle hyperactivity of grimacing muscles.

  15. Artificial muscle: facts and fiction.

    Science.gov (United States)

    Schaub, Marcus C

    2011-12-19

    Mechanical devices are sought to support insufficient or paralysed striated muscles including the failing heart. Nickel-titanium alloys (nitinol) present the following two properties: (i) super-elasticity, and (ii) the potential to assume different crystal structures depending on temperature and/or stress. Starting from the martensite state nitinol is able to resume the austenite form (state of low potential energy and high entropy) even against an external resistance. This one-way shape change is deployed in self-expanding vascular stents. Heating induces the force generating transformation from martensite to the austenite state while cooling induces relaxation back to the martensite state. This two-way shape change oscillating between the two states may be used in cyclically contracting support devices of silicon-coated nitinol wires. Such a contractile device sutured to the right atrium has been tested in vitro in a bench model and in vivo in sheep. The contraction properties of natural muscles, specifically of the myocardium, and the tight correlation with ATP production by oxidative phosphorylation in the mitochondria is briefly outlined. Force development by the nitinol device cannot be smoothly regulated as in natural muscle. Its mechanical impact is forced onto the natural muscle regardless of the actual condition with regard to metabolism and Ca2+-homeostasis. The development of artificial muscle on the basis of nitinol wires is still in its infancy. The nitinol artificial muscle will have to prove its viability in the various clinical settings.

  16. Muscle histochemistry in chronic alcoholism

    Directory of Open Access Journals (Sweden)

    M. L. Ferraz

    1989-06-01

    Full Text Available Twenty-two chronic acoholic patients were assessed by neurologic examination and muscle biopsy. The patients manifested proximal muscular weakness to a variable extent. One case presented as an acute bout of myopathy, according to the Manual Muscle Test, MMT. The most prominent histologic feature observed was muscle atrophy (95.3% better evidenced through the ATPase stain with the predominance of type II A fibers (71.4%. Lack of the mosaic pattern (type grouping seen in 76% of the cases and an important mitochondrial proliferation with intrasarcoplasmatic lipid accumulation in 63% of the patients. In case of acute presentation of muscle weakness the. pathological substrate is quite different, i.e. presence of myositis mainly interstitial characterized by lymphoplasmocytic infiltrate and several spots of necrosis like Zencker degeneration. Based on histologic criteria, our data suggest that: the main determinant of muscle weakness seen in chronic alcoholic patients is neurogenic in origin (alcoholic polineuropathy; the direct toxic action of ethanol under the skeletal muscle is closely related to the mitochondrial metabolism; the so-called acute alcoholic myopathy has probably viral etiology.

  17. Variability of femoral muscle attachments.

    Science.gov (United States)

    Duda, G N; Brand, D; Freitag, S; Lierse, W; Schneider, E

    1996-09-01

    Analytical and experimental models of the musculoskeletal system often assume single values rather than ranges for anatomical input parameters. The hypothesis of the present study was that anatomical variability significantly influences the results of biomechanical analyses, specifically regarding the moment arms of the various thigh muscles. Insertions and origins of muscles crossing or attaching to the femur were digitized in six specimens. Muscle volumes were measured; muscle attachment area and centroid location were computed. To demonstrate the influence of inter-individual anatomic variability on a mechanical modeling parameter, the corresponding range of muscle moment arms were calculated. Standard deviations, as a percentage of the mean, were about 70% for attachment area and 80% for muscle volume and attachment centroid location. The resulting moment arms of the m. gluteus maximus and m. rectus femoris were especially sensitive to anatomical variations (SD 65%). The results indicate that sensitivity to anatomical variations should be analyzed in any investigation simulating musculoskeletal interactions. To avoid misinterpretations, investigators should consider using several anatomical configurations rather than relying on a mean data set.

  18. Influence of muscle geometry on shortening speed of fibre, aponeurosis and muscle

    NARCIS (Netherlands)

    Zuurbier, C. J.; Huijing, P. A.

    1992-01-01

    The influence of muscle geometry on muscle shortening of the gastrocnemius medialis muscle (GM) of the rat was studied. Using cinematography, GM geometry was studied during isokinetic concentric activity at muscle lengths ranging from 85 to 105% of the optimum muscle length. The shortening speed of

  19. Redox regulation of calcium release in skeletal and cardiac muscle

    Directory of Open Access Journals (Sweden)

    CECILIA HIDALGO

    2002-01-01

    Full Text Available In skeletal and cardiac muscle cells, specific isoforms of the Ryanodine receptor channels mediate Ca2+ release from the sarcoplasmic reticulum. These channels are highly susceptible to redox modifications, which regulate channel activity. In this work, we studied the effects of Ca2+ (endogenous agonist and Mg2+ (endogenous inhibitor on the kinetics of Ca2+ release from sarcoplasmic reticulum vesicles isolated from skeletal or cardiac mammalian muscle. Native skeletal vesicles exhibited maximal stimulation of release kinetics by 10-20 µM [Ca2+], whereas in native cardiac vesicles, maximal stimulation of release required only 1 µM [Ca2+]. In 10 µM [Ca2+], free [Mg2+] < 0.1 mM produced marked inhibition of release from skeletal vesicles but free [Mg2+] ­ 0.8 mM did not affect release from cardiac vesicles. Incubation of skeletal or cardiac vesicles with the oxidant thimerosal increased their susceptibility to stimulation by Ca2+ and decreased the inhibitory effect of Mg2+ in skeletal vesicles. Sulfhydryl-reducing agents fully reversed the effects of thimerosal. The endogenous redox species, glutathione disulfide and S-nitrosoglutathione, also stimulated release from skeletal sarcoplasmic reticulum vesicles. In 10 µM [Ca2+], 35S-nitrosoglutathione labeled a protein fraction enriched in release channels through S-glutathiolation. Free [Mg2+] 1 mM or decreasing free [Ca2+] to the nM range prevented this reaction. Possible physiological and pathological consequences of redox modification of release channels on Ca2+ signaling in heart and muscle cells are discussed

  20. Assessment of muscle fatigue using electromygraphm sensing

    Science.gov (United States)

    Helmi, Muhammad Hazimin Bin; Ping, Chew Sue; Ishak, Nur Elliza Binti; Saad, Mohd Alimi Bin Mohd; Mokhtar, Anis Shahida Niza Binti

    2017-08-01

    Muscle fatigue is condition of muscle decline in ability after undergoing any physical activity. Observation of the muscle condition of an athlete during training is crucial to prevent or minimize injury and able to achieve optimum performance in actual competition. The aim of this project is to develop a muscle monitoring system to detect muscle fatigue in swimming athlete. This device is capable to measure muscle stress level of the swimmer and at the same time provide indication of muscle fatigue level to trainer. Electromyography signal was recorded from the muscle movement while practicing the front crawl stroke repetitively. The time domain data was processed to frequency spectra in order to study the effect of muscle fatigue. The results show that the recorded EMG signal is able to sense muscle fatigue.

  1. Sarcomere lattice geometry influences cooperative myosin binding in muscle.

    Directory of Open Access Journals (Sweden)

    Bertrand C W Tanner

    2007-07-01

    Full Text Available In muscle, force emerges from myosin binding with actin (forming a cross-bridge. This actomyosin binding depends upon myofilament geometry, kinetics of thin-filament Ca(2+ activation, and kinetics of cross-bridge cycling. Binding occurs within a compliant network of protein filaments where there is mechanical coupling between myosins along the thick-filament backbone and between actin monomers along the thin filament. Such mechanical coupling precludes using ordinary differential equation models when examining the effects of lattice geometry, kinetics, or compliance on force production. This study uses two stochastically driven, spatially explicit models to predict levels of cross-bridge binding, force, thin-filament Ca(2+ activation, and ATP utilization. One model incorporates the 2-to-1 ratio of thin to thick filaments of vertebrate striated muscle (multi-filament model, while the other comprises only one thick and one thin filament (two-filament model. Simulations comparing these models show that the multi-filament predictions of force, fractional cross-bridge binding, and cross-bridge turnover are more consistent with published experimental values. Furthermore, the values predicted by the multi-filament model are greater than those values predicted by the two-filament model. These increases are larger than the relative increase of potential inter-filament interactions in the multi-filament model versus the two-filament model. This amplification of coordinated cross-bridge binding and cycling indicates a mechanism of cooperativity that depends on sarcomere lattice geometry, specifically the ratio and arrangement of myofilaments.

  2. Dysregulation of muscle glycogen synthase in recovery from exercise in type 2 diabetes

    DEFF Research Database (Denmark)

    Pedersen, Andreas J T; Hingst, Janne Rasmuss; Friedrichsen, Martin

    2015-01-01

    AIMS/HYPOTHESIS: Insulin and exercise stimulate skeletal muscle glycogen synthase (GS) activity by dephosphorylation and changes in kinetic properties. The aim of this study was to investigate the effects of insulin, exercise and post-exercise insulin stimulation on GS phosphorylation, activity a...... and increased phosphorylation at sites 2 + 2a in type 2 diabetes in the recovery period imply an impaired response to exercise....

  3. Modelling of Muscle Force Distributions During Barefoot and Shod Running

    Directory of Open Access Journals (Sweden)

    Sinclair Jonathan

    2015-09-01

    Full Text Available Research interest in barefoot running has expanded considerably in recent years, based around the notion that running without shoes is associated with a reduced incidence of chronic injuries. The aim of the current investigation was to examine the differences in the forces produced by different skeletal muscles during barefoot and shod running. Fifteen male participants ran at 4.0 m·s-1 (± 5%. Kinematics were measured using an eight camera motion analysis system alongside ground reaction force parameters. Differences in sagittal plane kinematics and muscle forces between footwear conditions were examined using repeated measures or Freidman’s ANOVA. The kinematic analysis showed that the shod condition was associated with significantly more hip flexion, whilst barefoot running was linked with significantly more flexion at the knee and plantarflexion at the ankle. The examination of muscle kinetics indicated that peak forces from Rectus femoris, Vastus medialis, Vastus lateralis, Tibialis anterior were significantly larger in the shod condition whereas Gastrocnemius forces were significantly larger during barefoot running. These observations provide further insight into the mechanical alterations that runners make when running without shoes. Such findings may also deliver important information to runners regarding their susceptibility to chronic injuries in different footwear conditions.

  4. Morphogenesis of Kinetic Reciprocal Frames

    DEFF Research Database (Denmark)

    Parigi, Dario; Sassone, Mario

    2011-01-01

    Kinetic structures in civil engineering and architecture gained considerable more attention in the very recent years as a practical solution to face time dependant performances. Realized projects are mostly bridges, retractable roofs, while in architecture the trend follows the category of intera......Kinetic structures in civil engineering and architecture gained considerable more attention in the very recent years as a practical solution to face time dependant performances. Realized projects are mostly bridges, retractable roofs, while in architecture the trend follows the category...... (RF) were studied in the past as a practical solution to span distances with shorter elements. Leonardo da Vinci discovered interesting RF patterns and studied three dimensional arch structures for bridges. RF are generally defined as structures that forms closed circuits of forces, and where elements...

  5. Kinetic approach to relativistic dissipation

    Science.gov (United States)

    Gabbana, A.; Mendoza, M.; Succi, S.; Tripiccione, R.

    2017-08-01

    Despite a long record of intense effort, the basic mechanisms by which dissipation emerges from the microscopic dynamics of a relativistic fluid still elude complete understanding. In particular, several details must still be finalized in the pathway from kinetic theory to hydrodynamics mainly in the derivation of the values of the transport coefficients. In this paper, we approach the problem by matching data from lattice-kinetic simulations with analytical predictions. Our numerical results provide neat evidence in favor of the Chapman-Enskog [The Mathematical Theory of Non-Uniform Gases, 3rd ed. (Cambridge University Press, Cambridge, U.K., 1970)] procedure as suggested by recent theoretical analyses along with qualitative hints at the basic reasons why the Chapman-Enskog expansion might be better suited than Grad's method [Commun. Pure Appl. Math. 2, 331 (1949), 10.1002/cpa.3160020403] to capture the emergence of dissipative effects in relativistic fluids.

  6. Kinetic theory of tearing instability

    International Nuclear Information System (INIS)

    Hazeltine, R.D.; Dobrott, D.; Wang, T.S.

    1975-01-01

    The guiding-center kinetic equation with Fokker-Planck collision term is used to study, in cylindrical geometry, a class of dissipative instabilities of which the classical tearing mode is an archetype. Variational solution of the kinetic equation obviates the use of an approximate Ohm's law or adiabatic assumption, as used in previous studies, and it provides a dispersive relation which is uniformly valid for any ratio of wave frequency to collision frequency. One result of using the rigorous collision operator is the prediction of a new instability. This instability, driven by the electron temperature gradient, is predicted to occur under the long mean-free path conditions of present tokamak experiments, and has significant features in common with the kink-like oscillations observed in such experiments

  7. Kinetics of cadmium hydroxide precipitation

    International Nuclear Information System (INIS)

    Patterson, J.W.; Marani, D.; Luo, B.; Swenson, P.

    1987-01-01

    This paper presents some preliminary results on the kinetics of Cd(OH)/sub 2/ precipitation, both in the absence and the presence of citric acid as an inhibiting agent. Batch and continuous stirred tank reactor (CSTR) precipitation studies are performed by mixing equal volumes of NaOH and Cd(NO/sub 3/)/sub 2/ solutions, in order to avoid localized supersaturation conditions. The rate of metal removal from the soluble phase is calculated from the mass balance for the CSTR precipitation tests. In addition, precipitation kinetics are studied in terms of nucleation and crystal growth rates, by means of a particle counter that allows a population balance analysis for the precipitation reactor at steady state conditions

  8. Art Engineering and Kinetic Art

    Directory of Open Access Journals (Sweden)

    Barış Yılmaz

    2014-12-01

    Full Text Available Performing an art, either by painting or by sculpturing, requires to be interdisciplinary. When an artist creates his/her work of art, the process he/she realizes is supported by different engineering disciplines. Therefore, especially modern artists need to understand engineering science and this results in transforming artists into engineers. Opportunities provided by technology and science enable artists to expand his/her vision and to improve his/her works. Especially kinetic art has become an approach that combines art with engineering. Kinetic art, which is nourished with varied disciplines, is an excellent example to prove that art is interdisciplinary and to show the relationship between artist/art and engineering.

  9. Modeling the isochronal crystallization kinetics

    International Nuclear Information System (INIS)

    Sahay, S.S.; Krishnan, Karthik

    2004-01-01

    The classical Johnson-Mehl-Avrami-Kolmogorov (JMAK) model, originally formulated for the isothermal condition, is often used in conjunction with additivity principle for modeling the non-isothermal crystallization kinetics. This approach at times results in significant differences between the model prediction and experimental data. In this article, a modification to this approach has been imposed via an additional functional relationship between the activation energy and heating rate. The methodology has been validated with experimental isochronal crystallization kinetic data in Se 71 Te 20 Sb 9 glass and Ge 20 Te 80 systems. It has been shown that the functional relationship between heating rate and activation energy, ascribed to the reduction in apparent activation energy due to increasing non-isothermality, provides better phenomenological description and therefore improves the prediction capability of the JMAK model under isochronal condition

  10. Muscular Oxygen Uptake Kinetics in Aged Adults.

    Science.gov (United States)

    Koschate, J; Drescher, U; Baum, K; Eichberg, S; Schiffer, T; Latsch, J; Brixius, K; Hoffmann, U

    2016-06-01

    Pulmonary oxygen uptake (V˙O2) kinetics and heart rate kinetics are influenced by age and fitness. Muscular V˙O2 kinetics can be estimated from heart rate and pulmonary V˙O2. In this study the applicability of a test using pseudo-random binary sequences in combination with a model to estimate muscular V˙O2 kinetics was tested. Muscular V˙O2 kinetics were expected to be faster than pulmonary V˙O2 kinetics, slowed in aged subjects and correlated with maximum V˙O2 and heart rate kinetics. 27 elderly subjects (73±3 years; 81.1±8.2 kg; 175±4.7 cm) participated. Cardiorespiratory kinetics were assessed using the maximum of cross-correlation functions, higher maxima implying faster kinetics. Muscular V˙O2 kinetics were faster than pulmonary V˙O2 kinetics (0.31±0.1 vs. 0.29±0.1 s; p=0.004). Heart rate kinetics were not correlated with muscular or pulmonary V˙O2 kinetics or maximum V˙O2. Muscular V˙O2 kinetics correlated with maximum V˙O2 (r=0.35; p=0.033). This suggests, that muscular V˙O2 kinetics are faster than estimates from pulmonary V˙O2 and related to maximum V˙O2 in aged subjects. In the future this experimental approach may help to characterize alterations in muscular V˙O2 under various conditions independent of motivation and maximal effort. © Georg Thieme Verlag KG Stuttgart · New York.

  11. Bumetanide kinetics in renal failure

    International Nuclear Information System (INIS)

    Pentikaeinen, P.J.P.; Pasternack, A.; Lampainen, E.; Neuvonen, P.J.; Penttilae, A.

    1985-01-01

    To study the effects of renal failure on bumetanide kinetics, the authors administered single intravenous doses of 1.0 mg/3.08 microCi 14 C-bumetanide to six healthy subjects and 22 patients with variable degrees of renal failure. The kinetics of 14 C-bumetanide and total 14 C were adequately described by a two-compartment open model in the control subjects and in the patients. The volume of the central compartment and the distribution t1/2 were of the same order in both groups, whereas the mean (+/- SE) volume at steady state was larger (22.1 +/- 1.6 and 16.9 +/- 1.0 L) and the elimination t1/2 was longer (1.9 +/- 0.2 and 1.4 +/- 0.1 hours) in patients with renal failure than in healthy controls. Bumetanide renal clearance was lower (10 +/- 3 and 90 +/- 13 ml/min) in patients than in subjects and correlated with creatinine clearance (r = 0.784) and log serum creatinine level (r = -0.843), whereas nonrenal clearance was significantly higher in the patients (153 +/- 14 and 99 +/- 6 ml/min). Bumetanide total plasma clearance did not significantly change. The non-protein-bound, free fraction of bumetanide was higher in patients and correlated with plasma albumin levels (r = -0.777). The kinetics of total 14 C showed similar but greater changes than those of 14C-bumetanide. Thus the most important changes in bumetanide kinetics in patients with renal failure are low renal clearance and a high free fraction, with a consequent increase in nonrenal clearance, volume of distribution, and elimination t1/2

  12. Production kinetics of zirconium tetrachloride

    International Nuclear Information System (INIS)

    Sudjoko, D.; Masduki, B.; Sunardjo; Sulistyo, B.

    1996-01-01

    This research was intended to study the kinetics of zirconium tetrachloride production. The process was carried out in semi continuous reactor, equipped with heater, temperature controller, sublimator and scrubber. The variables investigated were time, temperature and the pellet forming pressure. Within the range of variables studied, the expression of the process in the chemical reaction controller region and diffusion controller region were both presented. (author)

  13. On the kinetic energy density

    International Nuclear Information System (INIS)

    Lombard, R.J.; Mas, D.; Moszkowski, S.A.

    1991-01-01

    We discuss two expressions for the density of kinetic energy which differ by an integration by parts. Using the Wigner transform we shown that the arithmetic mean of these two terms is closely analogous to the classical value. Harmonic oscillator wavefunctions are used to illustrate the radial dependence of these expressions. We study the differences they induce through effective mass terms when performing self-consistent calculations. (author)

  14. Kinetics of UO2 sintering

    International Nuclear Information System (INIS)

    Ristic, M.M.

    1962-01-01

    Detailed conclusions related to the UO 2 sintering can be drawn from investigating the kinetics of the sintering process. This report gives an thorough analysis of the the data concerned with sintering available in the literature taking into account the Jander and Arrhenius laws. This analysis completes the study of influence of the O/U ratio and the atmosphere on the sintering. Results presented are fundamentals of future theoretical and experimental work related to characterisation of the UO 2 sintering process

  15. The reproducibility of different metabolic markers for muscle fiber type distributions investigated by functional "3"1P-MRS during dynamic exercise

    International Nuclear Information System (INIS)

    Rzanny, Reinhard; Hiepe, Patrick; Gussew, Alexander; Reichenbach, Juergen R.; Stutzig, Norman; Thorhauer, Hans-Alexander

    2016-01-01

    The objective of the study was to investigate the reproducibility of exercise induced pH-heterogeneity by splitting of the inorganic phosphate (Pi) signal in the corresponding "3"1P-MRS spectra and to compare results of this approach with other fiber-type related markers, like phosphocreatine/adenosine triphosphate (PCr/ATP) ratio, and PCr-recovery parameters. Subjects (N = 3) with different sportive background were tested in 10 test sessions separated by at least 3 days. A MR-compatible pedal ergometer was used to perform the exercise and to induce a pH-based splitting of the Pi-signal in "3"1P-MR spectra of the medial gastrocnemius muscle. The PCr recovery was analyzed using a non-negative least square algorithm (NNLS) and multi-exponential regression analysis to estimate the number of non-exponential components as well as their amplitude and time constant. The reproducibility of the estimated metabolic marker and the resulting fiber-type distributions between the 10 test sessions were compared. The reproducibility (standard deviation between measurements) based on (1) Pi components varied from 2% to 4%, (2) PCr recovery time components varied from 10% to 12% and (3) phosphate concentrations at rest varied from 8% to 11% between test sessions. Due to the sportive activity differences between the 3 subjects were expected in view of fiber type distribution. All estimated markers indicate the highest type I percentage for volunteer 3 medium for volunteer 2 and the lowest for volunteer 1. The relative high reproducibility of pH dependent Pi components during exercise indicates a high potential of this method to estimate muscle fiber-type distributions in vivo. To make this method usable not only to detect differences in muscle fiber distributions but also to determine individual fiber-type volume contents it is therefore recommended to validate this marker by histological methods and to reveal the effects of muscle fiber recruitments and fiber-type specific Pi

  16. The reproducibility of different metabolic markers for muscle fiber type distributions investigated by functional {sup 31}P-MRS during dynamic exercise

    Energy Technology Data Exchange (ETDEWEB)

    Rzanny, Reinhard; Hiepe, Patrick; Gussew, Alexander; Reichenbach, Juergen R. [Univ. Hospital Jena (Germany). Medical Physics Group, Inst. of Diagnostics and Interventional Radiology; Stutzig, Norman [Univ. of Stuttgart (Germany). Exercise Science, Inst. of Sport and Movement Science; Thorhauer, Hans-Alexander [Friedrich-Schiller-Univ. Jena (Germany). Exercise Science, Inst. of Sports Science

    2016-07-01

    The objective of the study was to investigate the reproducibility of exercise induced pH-heterogeneity by splitting of the inorganic phosphate (Pi) signal in the corresponding {sup 31}P-MRS spectra and to compare results of this approach with other fiber-type related markers, like phosphocreatine/adenosine triphosphate (PCr/ATP) ratio, and PCr-recovery parameters. Subjects (N = 3) with different sportive background were tested in 10 test sessions separated by at least 3 days. A MR-compatible pedal ergometer was used to perform the exercise and to induce a pH-based splitting of the Pi-signal in {sup 31}P-MR spectra of the medial gastrocnemius muscle. The PCr recovery was analyzed using a non-negative least square algorithm (NNLS) and multi-exponential regression analysis to estimate the number of non-exponential components as well as their amplitude and time constant. The reproducibility of the estimated metabolic marker and the resulting fiber-type distributions between the 10 test sessions were compared. The reproducibility (standard deviation between measurements) based on (1) Pi components varied from 2% to 4%, (2) PCr recovery time components varied from 10% to 12% and (3) phosphate concentrations at rest varied from 8% to 11% between test sessions. Due to the sportive activity differences between the 3 subjects were expected in view of fiber type distribution. All estimated markers indicate the highest type I percentage for volunteer 3 medium for volunteer 2 and the lowest for volunteer 1. The relative high reproducibility of pH dependent Pi components during exercise indicates a high potential of this method to estimate muscle fiber-type distributions in vivo. To make this method usable not only to detect differences in muscle fiber distributions but also to determine individual fiber-type volume contents it is therefore recommended to validate this marker by histological methods and to reveal the effects of muscle fiber recruitments and fiber-type specific

  17. Diseases and disorders of muscle.

    Science.gov (United States)

    Pearson, A M; Young, R B

    1993-01-01

    Muscle may suffer from a number of diseases or disorders, some being fatal to humans and animals. Their management or treatment depends on correct diagnosis. Although no single method may be used to identify all diseases, recognition depends on the following diagnostic procedures: (1) history and clinical examination, (2) blood biochemistry, (3) electromyography, (4) muscle biopsy, (5) nuclear magnetic resonance, (6) measurement of muscle cross-sectional area, (7) tests of muscle function, (8) provocation tests, and (9) studies on protein turnover. One or all of these procedures may prove helpful in diagnosis, but even then identification of the disorder may not be possible. Nevertheless, each of these procedures can provide useful information. Among the most common diseases in muscle are the muscular dystrophies, in which the newly identified muscle protein dystrophin is either absent or present at less than normal amounts in both Duchenne and Becker's muscular dystrophy. Although the identification of dystrophin represents a major breakthrough, treatment has not progressed to the experimental stage. Other major diseases of muscle include the inflammatory myopathies and neuropathies. Atrophy and hypertrophy of muscle and the relationship of aging, exercise, and fatigue all add to our understanding of the behavior of normal and abnormal muscle. Some other interesting related diseases and disorders of muscle include myasthenia gravis, muscular dysgenesis, and myclonus. Disorders of energy metabolism include those caused by abnormal glycolysis (Von Gierke's, Pompe's, Cori-Forbes, Andersen's, McArdle's, Hers', and Tauri's diseases) and by the acquired diseases of glycolysis (disorders of mitochondrial oxidation). Still other diseases associated with abnormal energy metabolism include lipid-related disorders (carnitine and carnitine palmitoyl-transferase deficiencies) and myotonic syndromes (myotonia congenita, paramyotonia congenita, hypokalemic and hyperkalemic

  18. KINETIC ALGORITHMS FOR HARBOUR MANAGEMENT

    Directory of Open Access Journals (Sweden)

    C. M. Gold

    2012-07-01

    Full Text Available Modern harbour management for a busy port needs to resolve a variety of simultaneous problems. Harbour traffic may be busy and the waterways congested, both by the major shipping and by the attendant harbour tugs. The harbour channel may be narrow and tortuous, and rapidly changing tides may require frequent course adjustments. Navigation aids must be clearly specified and immediately identifiable, in order to permit safe passage for the vessels. This requires a GIS with attributes not easily available with traditional products. The GeoVS system is a kinetic GIS with full three-dimensional visualisation, so that ships, bathymetry and landscape may be viewed in a form that is immediately understandable to both harbour pilots and the harbour authority. The system is kinetic because the data structures used to preserve the topological relationships between ships, seafloor and coastline are able to be maintained on a real-time basis, taking account of ship movement recorded on the compulsory AIS (Automatic Information System beacons. Maintenance of this real-time topology allows for easy detection of potential collisions, as well as real-time bathymetric estimations, necessary to prevent ship grounding in highly tidal environments. The system, based on previous research into kinetic Voronoi diagrams, as well as development of a completely new graphical engine, is now in commercial production, where its advantages over simpler twodimensional models without automatic collision and grounding detection are becoming evident. Other applications are readily envisaged, and will be addressed in the near future.

  19. Oxidation kinetics of corium pool

    Energy Technology Data Exchange (ETDEWEB)

    Sulatsky, A.A., E-mail: andrei314@mail.ru [Alexandrov Research Institute of Technologies (NITI), Sosnovy Bor (Russian Federation); Smirnov, S.A. [D.V. Efremov Scientific Research Institute of Electrophysical Apparatus (NIIEFA), St. Petersburg (Russian Federation); Granovsky, V.S.; Khabensky, V.B.; Krushinov, E.V.; Vitol, S.A.; Kotova, S.Yu. [Alexandrov Research Institute of Technologies (NITI), Sosnovy Bor (Russian Federation); Fischer, M.; Hellmann, S. [AREVA NP GmbH, Erlangen (Germany); Tromm, W.; Miassoedov, A. [Forschungzentrum Karlsruhe (FZK), Karlsruhe (Germany); Bottomley, D. [EUROPÄISCHE KOMMISSION, Joint Research Centre Institut für Transurane (ITU), Karlsruhe (Germany); Piluso, P. [CEA Cadarache-DEN/DTN/STRI, St.Paul-lez-Durance (France); Barrachin, M. [Institut de Radioprotection et Sûreté Nucléaire, St.Paul-lez-Durance (France)

    2013-09-15

    Highlights: • The analysis of experimental data on molten corium oxidation was been carried out. • The analysis has revealed the main factors influencing the oxidation kinetics. • The analysis was used for developing a qualitative analytical model. • The numerical modeling has confirmed the results of experimental data analysis. -- Abstract: Experimental, theoretical and numerical studies of oxidation kinetics of an open surface corium pool have been reported. The experiments have been carried out within OECD MASCA program and ISTC METCOR, METCOR-P and EVAN projects. It has been shown that the melt oxidation is controlled by an oxidant supply to the melt free surface from the atmosphere, not by the reducer supply from the melt. The project experiments have not detected any input of the zirconium oxidation kinetics into the process chemistry. The completed analysis puts forward a simple analytical model, which gives an explanation of the main features of melt oxidation process. The numerical modeling results are in good agreement with experimental data and theoretical considerations.

  20. Oxidation kinetics of corium pool

    International Nuclear Information System (INIS)

    Sulatsky, A.A.; Smirnov, S.A.; Granovsky, V.S.; Khabensky, V.B.; Krushinov, E.V.; Vitol, S.A.; Kotova, S.Yu.; Fischer, M.; Hellmann, S.; Tromm, W.; Miassoedov, A.; Bottomley, D.; Piluso, P.; Barrachin, M.

    2013-01-01

    Highlights: • The analysis of experimental data on molten corium oxidation was been carried out. • The analysis has revealed the main factors influencing the oxidation kinetics. • The analysis was used for developing a qualitative analytical model. • The numerical modeling has confirmed the results of experimental data analysis. -- Abstract: Experimental, theoretical and numerical studies of oxidation kinetics of an open surface corium pool have been reported. The experiments have been carried out within OECD MASCA program and ISTC METCOR, METCOR-P and EVAN projects. It has been shown that the melt oxidation is controlled by an oxidant supply to the melt free surface from the atmosphere, not by the reducer supply from the melt. The project experiments have not detected any input of the zirconium oxidation kinetics into the process chemistry. The completed analysis puts forward a simple analytical model, which gives an explanation of the main features of melt oxidation process. The numerical modeling results are in good agreement with experimental data and theoretical considerations

  1. Aluminum corrosion product release kinetics

    Energy Technology Data Exchange (ETDEWEB)

    Edwards, Matt, E-mail: Matthew.Edwards@cnl.ca; Semmler, Jaleh; Guzonas, Dave; Chen, Hui Qun; Toor, Arshad; Hoendermis, Seanna

    2015-07-15

    Highlights: • Release of Al corrosion product was measured in simulated post-LOCA sump solutions. • Increased boron was found to enhance Al release kinetics at similar pH. • Models of Al release as functions of time, temperature, and pH were developed. - Abstract: The kinetics of aluminum corrosion product release was examined in solutions representative of post-LOCA sump water for both pressurized water and pressurized heavy-water reactors. Coupons of AA 6061 T6 were exposed to solutions in the pH 7–11 range at 40, 60, 90 and 130 °C. Solution samples were analyzed by inductively coupled plasma atomic emission spectroscopy, and coupon samples were analyzed by secondary ion mass spectrometry. The results show a distinct “boron effect” on the release kinetics, expected to be caused by an increase in the solubility of the aluminum corrosion products. New models were developed to describe both sets of data as functions of temperature, time, and pH (where applicable)

  2. Heterogeneity among muscle precursor cells in adult skeletal muscles with differing regenerative capacities.

    Science.gov (United States)

    Pavlath, G K; Thaloor, D; Rando, T A; Cheong, M; English, A W; Zheng, B

    1998-08-01

    Skeletal muscle has a remarkable capacity to regenerate after injury, although studies of muscle regeneration have heretofore been limited almost exclusively to limb musculature. Muscle precursor cells in skeletal muscle are responsible for the repair of damaged muscle. Heterogeneity exists in the growth and differentiation properties of muscle precursor cell (myoblast) populations throughout limb development but whether the muscle precursor cells differ among adult skeletal muscles is unknown. Such heterogeneity among myoblasts in the adult may give rise to skeletal muscles with different regenerative capacities. Here we compare the regenerative response of a masticatory muscle, the masseter, to that of limb muscles. After exogenous trauma (freeze or crush injuries), masseter muscle regenerated much less effectively than limb muscle. In limb muscle, normal architecture was restored 12 days after injury, whereas in masseter muscle, minimal regeneration occurred during the same time period. Indeed, at late time points, masseter muscles exhibited increased fibrous connective tissue in the region of damage, evidence of ineffective muscle regeneration. Similarly, in response to endogenous muscle injury due to a muscular dystrophy, widespread evidence of impaired regeneration was present in masseter muscle but not in limb muscle. To explore the cellular basis of these different regenerative capacities, we analyzed the myoblast populations of limb and masseter muscles both in vivo and in vitro. From in vivo analyses, the number of myoblasts in regenerating muscle was less in masseter compared with limb muscle. Assessment of population growth in vitro indicated that masseter myoblasts grow more slowly than limb myoblasts under identical conditions. We conclude that the impaired regeneration in masseter muscles is due to differences in the intrinsic myoblast populations compared to limb muscles.

  3. Imaging mass spectrometry reveals fiber-specific distribution of acetylcarnitine and contraction-induced carnitine dynamics in rat skeletal muscles.

    Science.gov (United States)

    Furuichi, Yasuro; Goto-Inoue, Naoko; Manabe, Yasuko; Setou, Mitsutoshi; Masuda, Kazumi; Fujii, Nobuharu L

    2014-10-01

    Carnitine is well recognized as a key regulator of long-chain fatty acyl group translocation into the mitochondria. In addition, carnitine, as acetylcarnitine, acts as an acceptor of excess acetyl-CoA, a potent inhibitor of pyruvate dehydrogenase. Here, we provide a new methodology for accurate quantification of acetylcarnitine content and determination of its localization in skeletal muscles. We used matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI-IMS) to visualize acetylcarnitine distribution in rat skeletal muscles. MALDI-IMS and immunohistochemistry of serial cross-sections showed that acetylcarnitine was enriched in the slow-type muscle fibers. The concentration of ATP was lower in muscle regions with abundant acetylcarnitine, suggesting a relationship between acetylcarnitine and metabolic activity. Using our novel method, we detected an increase in acetylcarnitine content after muscle contraction. Importantly, this increase was not detected using traditional biochemical assays of homogenized muscles. We also demonstrated that acetylation of carnitine during muscle contraction was concomitant with glycogen depletion. Our methodology would be useful for the quantification of acetylcarnitine and its contraction-induced kinetics in skeletal muscles. Copyright © 2014 Elsevier B.V. All rights reserved.

  4. Measurement of Gender Differences of Gastrocnemius Muscle and Tendon Using Sonomyography during Calf Raises: A Pilot Study

    Directory of Open Access Journals (Sweden)

    Guang-Quan Zhou

    2017-01-01

    Full Text Available Skeletal muscles are essential to the gender-specific characteristics of human movements. Sonomyography, a new signal for quantifying muscle activation, is of great benefit to understand muscle function through monitoring the real-time muscle architectural changes. The purpose of this pilot study was to investigate gender differences in the architectural changes of gastronomies muscle and tendon by using sonomyography during performing two-legged calf raising exercises. A motion analysis system was developed to extract sonomyography from ultrasound images together with kinematic and kinetic measurements. Tiny fascicle length changes among seven male subjects were observed at the initial part of calf raising, whereas the fascicle of seven female subjects shortened immediately. This result suggested that men would generate higher mechanical power output of plantar flexors to regulate their heavier body mass. In addition, the larger regression coefficient between the fascicle length and muscle force for the male subjects implied that higher muscle stiffness for the men was required in demand of maintaining their heavier body economically. The findings from the current study suggested that the body mass might play a factor in the gender difference in structural changes of muscle and tendon during motion. The sonomyography may provide valuable information in the understanding of the gender difference in human movements.

  5. Dynamic contrast-enhanced magnetic resonance imaging of the sarcopenic muscle

    Energy Technology Data Exchange (ETDEWEB)

    Nicolato, Elena; Farace, Paolo; Asperio, Roberto M; Marzola, Pasquina; Lunati, Ernesto; Sbarbati, Andrea; Osculati, Francesco [Dipartimento di Scienze Morfologico-Biomediche, Sezione di Anatomia ed Istologia, Università di Verona, Verona, I-37194 (Italy)

    2002-06-05

    Studies about capillarity of the aged muscle provided conflicting results and no data are currently available about the magnetic resonance imaging (MRI) in vivo characteristics of the microvascular bed in aged rats. We have studied age-related modifications of the skeletal muscle by in vivo T2-relaxometry and dynamic contrast-enhanced magnetic resonance imaging (CE-MRI) at high field intensity (4.7 T). The aim of the work was to test the hypothesis that the ageing process involves microvessels in skeletal muscle. The study was performed in 4-month-old (n = 6) and 20-month-old (n = 6) rats. At MRI examination, the relaxation time T2 of the gastrocnemius muscle showed no significant difference between these two groups. The kinetic of contrast penetration in the tissue showed that in 4-month-old rats the enhancement values of the signal intensity at different time-points were significantly higher than those found in senescent rats. The reported finding suggests that there is a modification of the microcirculatory function in skeletal muscle of aged rats. This work also demonstrates that CE-MRI allows for an in vivo quantification of the multiple biological processes involving the skeletal muscle during aging. Therefore, CE-MRI could represent a further tool for the follow up of tissue modification and therapeutic intervention both in patients with sarcopenia and in experimental models of this pathology.

  6. Dynamic contrast-enhanced magnetic resonance imaging of the sarcopenic muscle

    International Nuclear Information System (INIS)

    Nicolato, Elena; Farace, Paolo; Asperio, Roberto M; Marzola, Pasquina; Lunati, Ernesto; Sbarbati, Andrea; Osculati, Francesco

    2002-01-01

    Studies about capillarity of the aged muscle provided conflicting results and no data are currently available about the magnetic resonance imaging (MRI) in vivo characteristics of the microvascular bed in aged rats. We have studied age-related modifications of the skeletal muscle by in vivo T2-relaxometry and dynamic contrast-enhanced magnetic resonance imaging (CE-MRI) at high field intensity (4.7 T). The aim of the work was to test the hypothesis that the ageing process involves microvessels in skeletal muscle. The study was performed in 4-month-old (n = 6) and 20-month-old (n = 6) rats. At MRI examination, the relaxation time T2 of the gastrocnemius muscle showed no significant difference between these two groups. The kinetic of contrast penetration in the tissue showed that in 4-month-old rats the enhancement values of the signal intensity at different time-points were significantly higher than those found in senescent rats. The reported finding suggests that there is a modification of the microcirculatory function in skeletal muscle of aged rats. This work also demonstrates that CE-MRI allows for an in vivo quantification of the multiple biological processes involving the skeletal muscle during aging. Therefore, CE-MRI could represent a further tool for the follow up of tissue modification and therapeutic intervention both in patients with sarcopenia and in experimental models of this pathology

  7. EFFECTS OF AGE AND ACUTE MUSCLE FATIGUE ON REACTIVE POSTURAL CONTROL IN HEALTHY ADULTS

    Science.gov (United States)

    Papa, Evan V.; Foreman, K. Bo; Dibble, Lee E.

    2015-01-01

    BACKGROUND Falls can cause moderate to severe injuries such as hip fractures and head trauma in older adults. While declines in muscle strength and sensory function contribute to increased falls in older adults, skeletal muscle fatigue is often overlooked as an additional contributor to fall risk. The purpose of this investigation was to examine the effects of acute lower extremity muscle fatigue and age on reactive postural control in healthy adults. METHODS A sample of 16 individuals participated in this study (8 healthy older adults and 8 healthy young persons). Whole body kinematic and kinetic data were collected during anterior and posterior reproducible fall tests before (T0) and immediately after (T1) eccentric muscle fatiguing exercise, as well as after 15-minutes (T15) and 30-minutes (T30) of rest. FINDINGS Lower extremity joint kinematics of the stepping limb during the support (landing) phase of the anterior fall were significantly altered by the presence of acute muscle fatigue. Step velocity was significantly decreased during the anterior falls. Statistically significant main effects of age were found for step length in both fall directions. Effect sizes for all outcomes were small. No statistically significant interaction effects were found. INTERPRETATION Muscle fatigue has a measurable effect on lower extremity joint kinematics during simulated falls. These alterations appear to resolve within 15 minutes of recovery. The above deficits, coupled with a reduced step length, may help explain the increased fall risk in older adults. PMID:26351001

  8. Effects of age and acute muscle fatigue on reactive postural control in healthy adults.

    Science.gov (United States)

    Papa, Evan V; Foreman, K Bo; Dibble, Leland E

    2015-12-01

    Falls can cause moderate to severe injuries such as hip fractures and head trauma in older adults. While declines in muscle strength and sensory function contribute to increased falls in older adults, skeletal muscle fatigue is often overlooked as an additional contributor to fall risk. The purpose of this investigation was to examine the effects of acute lower extremity muscle fatigue and age on reactive postural control in healthy adults. A sample of 16 individuals participated in this study (8 healthy older adults and 8 healthy young persons). Whole body kinematic and kinetic data were collected during anterior and posterior reproducible fall tests before (T0) and immediately after (T1) eccentric muscle fatiguing exercise, as well as after 15-min (T15) and 30-min (T30) of rest. Lower extremity joint kinematics of the stepping limb during the support (landing) phase of the anterior fall were significantly altered by the presence of acute muscle fatigue. Step velocity was significantly decreased during the anterior falls. Statistically significant main effects of age were found for step length in both fall directions. Effect sizes for all outcomes were small. No statistically significant interaction effects were found. Muscle fatigue has a measurable effect on lower extremity joint kinematics during simulated falls. These alterations appear to resolve within 15 min of recovery. The above deficits, coupled with a reduced step length, may help explain the increased fall risk in older adults. Copyright © 2015 Elsevier Ltd. All rights reserved.

  9. Dynamic contrast-enhanced magnetic resonance imaging of the sarcopenic muscle

    Directory of Open Access Journals (Sweden)

    Sbarbati Andrea

    2002-06-01

    Full Text Available Abstract Background Studies about capillarity of the aged muscle provided conflicting results and no data are currently available about the magnetic resonance imaging (MRI in vivo characteristics of the microvascular bed in aged rats. We have studied age-related modifications of the skeletal muscle by in vivo T2-relaxometry and dynamic contrast-enhanced magnetic resonance imaging (CE-MRI at high field intensity (4.7 T. The aim of the work was to test the hypothesis that the ageing process involves microvessels in skeletal muscle. Methods The study was performed in 4-month-old (n = 6 and 20-month-old (n = 6 rats. Results At MRI examination, the relaxation time T2 of the gastrocnemius muscle showed no significant difference between these two groups. The kinetic of contrast penetration in the tissue showed that in 4-month-old rats the enhancement values of the signal intensity at different time-points were significantly higher than those found in senescent rats. Conclusion The reported finding suggests that there is a modification of the microcirculatory function in skeletal muscle of aged rats. This work also demonstrates that CE-MRI allows for an in vivo quantification of the multiple biological processes involving the skeletal muscle during aging. Therefore, CE-MRI could represent a further tool for the follow up of tissue modification and therapeutic intervention both in patients with sarcopenia and in experimental models of this pathology.

  10. R-spondin1 Controls Muscle Cell Fusion through Dual Regulation of Antagonistic Wnt Signaling Pathways

    Directory of Open Access Journals (Sweden)

    Floriane Lacour

    2017-03-01

    Full Text Available Wnt-mediated signals are involved in many important steps in mammalian regeneration. In multiple cell types, the R-spondin (Rspo family of secreted proteins potently activates the canonical Wnt/β-catenin pathway. Here, we identify Rspo1 as a mediator of skeletal muscle tissue repair. First, we show that deletion of Rspo1 results in global alteration of muscle regeneration kinetics following acute injury. We find that muscle progenitor cells lacking Rspo1 show delayed differentiation due to reduced activation of Wnt/β-catenin target genes. Furthermore, muscle cells lacking Rspo1 have a fusion phenotype leading to larger myotubes containing supernumerary nuclei both in vitro and in vivo. The increase in muscle fusion was dependent on downregulation of Wnt/β-catenin and upregulation of non-canonical Wnt7a/Fzd7/Rac1 signaling. We conclude that reciprocal control of antagonistic Wnt signaling pathways by Rspo1 in muscle stem cell progeny is a key step ensuring normal tissue architecture restoration following acute damage.

  11. Effect of Full-Length Carbon Fiber Insoles on Lower Limb Kinetics in Patients With Midfoot Osteoarthritis: A Pilot Study.

    Science.gov (United States)

    Yi, Taeim; Kim, Jung Hyun; Oh-Park, Mooyeon; Hwang, Ji Hye

    2018-03-01

    We investigated the effects of full-length carbon fiber (FCF) insoles on gait, muscle activity, kinetics, and pain in patients with midfoot osteoarthritis (OA). We enrolled 13 patients with unilateral midfoot OA (mild: Visual Analog Scale [VAS] range, 1-3; moderate, VAS range, 4-7) and healthy controls. All participants were asked to walk under two conditions: with and without FCF insole. The outcome measures were ground reaction force, quantitative gait parameters, electromyography activities and pain severity (VAS). In the patients with moderate midfoot OA, significantly longer gait cycle and higher muscle activity of lower limb during loading-response phase were observed while walking without FCF insoles. In the mild midfoot OA group, there was no significant difference in VAS score (without, 2.0 ± 1.0 vs. with, 2.0 ± 0.5) with FCF insole use. However, significantly reduced VAS score (without, 5.5 ± 1.4 vs. with, 2.0 ± 0.5) and muscle activity of the tibialis anterior and increased muscle activity of gastrocnemius were observed in the moderate midfoot OA group by using an FCF insole (P < 0.05). Full-length carbon fiber insoles can improve pain in individuals with moderate midfoot OA, which might be associated with changes in the kinetics and muscle activities of the lower limb. Taken together, the results of the present study suggest that FCF insoles may be used as a helpful option for midfoot OA.

  12. Muscle strength rather than muscle mass is associated with osteoporosis in older Chinese adults

    Directory of Open Access Journals (Sweden)

    Yixuan Ma

    2018-02-01

    Conclusion: Based on our study, muscle strength rather than muscle mass is negatively associated with OS in older people; thus, we should pay more attention to muscle strength training in the early stage of the OS.

  13. Effect of transcutaneous electrical muscle stimulation on muscle volume in patients with septic shock

    DEFF Research Database (Denmark)

    Poulsen, Jesper Brøndum; Møller, Kirsten; Jensen, Claus V

    2011-01-01

    Objective: Intensive care unit admission is associated with muscle wasting and impaired physical function. We investigated the effect of early transcutaneous electrical muscle stimulation on quadriceps muscle volume in patients with septic shock. Design: Randomized interventional study using...

  14. Repeated static contractions increase mitochondrial vulnerability toward oxidative stress in human skeletal muscle

    DEFF Research Database (Denmark)

    Sahlin, Kent; Nielsen, Jens Steen; Mogensen, Martin

    2006-01-01

    Repeated static contractions (RSC) induce large fluctuations in tissue oxygen tension and increase the generation of reactive oxygen species (ROS). This study investigated the effect of RSC on muscle contractility, mitochondrial respiratory function, and in vitro sarcoplasmic reticulum (SR) Ca(2......+) kinetics in human muscle. Ten male subjects performed five bouts of static knee extension with 10-min rest in between. Each bout of RSC (target torque 66% of maximal voluntary contraction torque) was maintained to fatigue. Muscle biopsies were taken preexercise and 0.3 and 24 h postexercise from vastus...... lateralis. Mitochondria were isolated and respiratory function measured after incubation with H(2)O(2) (HPX) or control medium (Con). Mitochondrial function was not affected by RSC during Con. However, RSC exacerbated mitochondrial dysfunction during HPX, resulting in decreased respiratory control index...

  15. Striated Muscle Function, Regeneration, and Repair

    Science.gov (United States)

    Shadrin, I.Y.; Khodabukus, A.; Bursac, N.

    2016-01-01

    As the only striated muscle tissues in the body, skeletal and cardiac muscle share numerous structural and functional characteristics, while exhibiting vastly different size and regenerative potential. Healthy skeletal muscle harbors a robust regenerative response that becomes inadequate after large muscle loss or in degenerative pathologies and aging. In contrast, the mammalian heart loses its regenerative capacity shortly after birth, leaving it susceptible to permanent damage by acute injury or chronic disease. In this review, we compare and contrast the physiology and regenerative potential of native skeletal and cardiac muscles, mechanisms underlying striated muscle dysfunction, and bioengineering strategies to treat muscle disorders. We focus on different sources for cellular therapy, biomaterials to augment the endogenous regenerative response, and progress in engineering and application of mature striated muscle tissues in vitro and in vivo. Finally, we discuss the challenges and perspectives in translating muscle bioengineering strategies to clinical practice. PMID:27271751

  16. Laser therapy of muscle injuries.

    Science.gov (United States)

    Dawood, Munqith S; Al-Salihi, Anam Rasheed; Qasim, Amenah Wala'a

    2013-05-01

    Low-level lasers are used in general therapy and healing process due to their good photo-bio-stimulation effects. In this paper, the effects of diode laser and Nd:YAG laser on the healing process of practically managed skeletal muscle trauma has been successfully studied. Standard impact trauma was induced by using a specially designed mechanical device. The impacted muscle was left for 3 days for complete development of blunt trauma. After that it was irradiated by five laser sessions for 5 days. Two types of lasers were used; 785-nm diode laser and 1.064-nm Nd:YAG laser, both in continuous and pulsed modes. A special electronic circuit was designed and implemented to modulate the diode laser for this purpose. Tissue samples of crushed skeletal muscle have been dissected from the injured irradiated muscle then bio-chemically analyzed for the regeneration of contractile and collagenous proteins using Lowry assay for protein determination and Reddy and Enwemeka assay for hydroxyproline determination. The results showed that both lasers stimulate the regeneration capability of traumatized skeletal muscle. The diode laser in CW and pulsed modes showed better results than the Nd:YAG in accelerating the preservation of the normal tissue content of collagenous and contractile proteins beside controlling the regeneration of non-functional fibrous tissue. This study proved that the healing achieved by the laser treatment was faster than the control group by 15-20 days.

  17. Protonmotive force in muscle mitochondria

    International Nuclear Information System (INIS)

    Stumpf, D.A.; Haas, R.; Eguren, L.A.; Parks, J.K.; Eilert, R.E.

    1982-01-01

    The protonmotive force (delta p) of muscle mitochondria was measured by estimating the distribution of 14C-labeled TPMP (trimethylphenylphosphonium iodide) and 14C-labeled acetate across the inner membrane of muscle mitochondria. The matrix volume was simultaneously determined using 3H-labeled H2O and 3H-labeled mannitol and repeated drying to distinguish the label in these 2 compounds. Rapid separation of mitochondria from the incubation medium by centrifugation through silicone oil avoids the problems of potential anaerobic conditions associated with conventional centrifugation and large volumes of trapped media associated with filtration. The value for delta p (mean +/- SD) was 192+/- 26 mV in 30 determinations with rat muscle mitochondria during state 4. Measurement of oxygen consumption allowed calculation of membrane conductance (Cm,H+) which was 0.49 +/- 0.18 nmol of H+/min/mg protein/mV. The values for delta p and Cm,H+ are reported for a variety of experimental conditions and are consistent with Mitchell's chemiosmotic theory. Biopsy specimens obtained from human muscle gave state-4 delta p values of 197+/- 30 mV (n .5) and Cm,H+ values of 0.52 +/- 0.12 nmol of H+/min/mg/mV (n . 4). This delta p assay is the first described for coupled mammalian muscle mitochondria and will be useful in assessing membrane function

  18. The Skeletal Muscle Satellite Cell

    Science.gov (United States)

    2011-01-01

    The skeletal muscle satellite cell was first described and named based on its anatomic location between the myofiber plasma and basement membranes. In 1961, two independent studies by Alexander Mauro and Bernard Katz provided the first electron microscopic descriptions of satellite cells in frog and rat muscles. These cells were soon detected in other vertebrates and acquired candidacy as the source of myogenic cells needed for myofiber growth and repair throughout life. Cultures of isolated myofibers and, subsequently, transplantation of single myofibers demonstrated that satellite cells were myogenic progenitors. More recently, satellite cells were redefined as myogenic stem cells given their ability to self-renew in addition to producing differentiated progeny. Identification of distinctively expressed molecular markers, in particular Pax7, has facilitated detection of satellite cells using light microscopy. Notwithstanding the remarkable progress made since the discovery of satellite cells, researchers have looked for alternative cells with myogenic capacity that can potentially be used for whole body cell-based therapy of skeletal muscle. Yet, new studies show that inducible ablation of satellite cells in adult muscle impairs myofiber regeneration. Thus, on the 50th anniversary since its discovery, the satellite cell’s indispensable role in muscle repair has been reaffirmed. PMID:22147605

  19. Nuclear Positioning in Muscle Development and Disease

    Directory of Open Access Journals (Sweden)

    Eric eFolker

    2013-12-01

    Full Text Available Muscle disease as a group is characterized by muscle weakness, muscle loss, and impaired muscle function. Although the phenotype is the same, the underlying cellular pathologies, and the molecular causes of these pathologies, are diverse. One common feature of many muscle disorders is the mispositioning of myonuclei. In unaffected individuals myonuclei are spaced throughout the periphery of the muscle fiber such that the distance between nuclei is maximized. However, in diseased muscles, the nuclei are often clustered within the center of the muscle cell. Although this phenotype has been acknowledged for several decades, it is often ignored as a contributor to muscle weakness. Rather, these nuclei are taken only as a sign of muscle repair. Here we review the evidence that mispositioned myonuclei are not merely a symptom of muscle disease but also a cause. Additionally, we review the working models for how myonuclei move from two different perspectives, from that of the nucleus and from that of the cytoskeleton. We further compare and contrast these mechanisms with the mechanisms of nuclear movement in other cell types both to draw general themes for nuclear movement and to identify muscle-specific considerations. Finally, we focus on factors that can be linked to muscle disease and find that genes that regulate myonuclear movement and positioning have been linked to muscular dystrophy. Although the cause-effect relationship is largely speculative, recent data indicate that the position of nuclei should no longer be considered only a means to diagnose muscle disease.

  20. Structure-function relationship of skeletal muscle provides inspiration for design of new artificial muscle

    Science.gov (United States)

    Gao, Yingxin; Zhang, Chi

    2015-03-01

    A variety of actuator technologies have been developed to mimic biological skeletal muscle that generates force in a controlled manner. Force generation process of skeletal muscle involves complicated biophysical and biochemical mechanisms; therefore, it is impossible to replace biological muscle. In biological skeletal muscle tissue, the force generation of a muscle depends not only on the force generation capacity of the muscle fiber, but also on many other important factors, including muscle fiber type, motor unit recruitment, architecture, structure and morphology of skeletal muscle, all of which have significant impact on the force generation of the whole muscle or force transmission from muscle fibers to the tendon. Such factors have often been overlooked, but can be incorporated in artificial muscle design, especially with the discovery of new smart materials and the development of innovative fabrication and manufacturing technologies. A better understanding of the physiology and structure-function relationship of skeletal muscle will therefore benefit the artificial muscle design. In this paper, factors that affect muscle force generation are reviewed. Mathematical models used to model the structure-function relationship of skeletal muscle are reviewed and discussed. We hope the review will provide inspiration for the design of a new generation of artificial muscle by incorporating the structure-function relationship of skeletal muscle into the design of artificial muscle.

  1. Structure–function relationship of skeletal muscle provides inspiration for design of new artificial muscle

    International Nuclear Information System (INIS)

    Gao, Yingxin; Zhang, Chi

    2015-01-01

    A variety of actuator technologies have been developed to mimic biological skeletal muscle that generates force in a controlled manner. Force generation process of skeletal muscle involves complicated biophysical and biochemical mechanisms; therefore, it is impossible to replace biological muscle. In biological skeletal muscle tissue, the force generation of a muscle depends not only on the force generation capacity of the muscle fiber, but also on many other important factors, including muscle fiber type, motor unit recruitment, architecture, structure and morphology of skeletal muscle, all of which have significant impact on the force generation of the whole muscle or force transmission from muscle fibers to the tendon. Such factors have often been overlooked, but can be incorporated in artificial muscle design, especially with the discovery of new smart materials and the development of innovative fabrication and manufacturing technologies. A better understanding of the physiology and structure–function relationship of skeletal muscle will therefore benefit the artificial muscle design. In this paper, factors that affect muscle force generation are reviewed. Mathematical models used to model the structure–function relationship of skeletal muscle are reviewed and discussed. We hope the review will provide inspiration for the design of a new generation of artificial muscle by incorporating the structure–function relationship of skeletal muscle into the design of artificial muscle. (topical review)

  2. CORRELATIONS BETWEEN MUSCLE MASS, MUSCLE STRENGTH, PHYSICAL PERFORMANCE, AND MUSCLE FATIGUE RESISTANCE IN COMMUNITY-DWELLING ELDERLY SUBJECTS

    Directory of Open Access Journals (Sweden)

    Elizabeth

    2016-03-01

    Full Text Available Objective: To determine the correlations between muscle mass, muscle strength, physical performance, and muscle fatigue resistance in community-dwelling elderly people in order to elucidate factors which contribute to elderly’s performance of daily activities. Methods: A cross-sectional study was conducted on community-dwelling elderly in Bandung from September to December 2014. One hundred and thirty elderly, 60 years old or above, were evaluated using bioelectrical impedance analysis to measure muscle mass; grip strength to measure muscle strength and muscle fatigue resistance; habitual gait speed to measure physical performance; and Global Physical Activity Questionnaire (GPAQ to assess physical activity. Results: There were significant positive correlations between muscle mass (r=0,27, p=0,0019, muscle strength (r=0,26, p=0,0024, and physical performance (r=0,32, p=0,0002 with muscle fatigue resistance. Physical performance has the highest correlation based on multiple regression test (p=0,0025. In association with muscle mass, the physical activity showed a significant positive correlation (r=0,42, p=0,0000. Sarcopenia was identified in 19 (14.61% of 130 subjects. Conclusions: It is suggested that muscle mass, muscle strength, and physical performance influence muscle fatigue resistance.

  3. Associations of passive muscle stiffness, muscle stretch tolerance, and muscle slack angle with range of motion: individual and sex differences.

    Science.gov (United States)

    Miyamoto, Naokazu; Hirata, Kosuke; Miyamoto-Mikami, Eri; Yasuda, Osamu; Kanehisa, Hiroaki

    2018-05-29

    Joint range of motion (ROM) is an important parameter for athletic performance and muscular injury risk. Nonetheless, a complete description of muscular factors influencing ROM among individuals and between men and women is lacking. We examined whether passive muscle stiffness (evaluated by angle-specific muscle shear modulus), tolerance to muscle stretch (evaluated by muscle shear modulus at end-ROM), and muscle slack angle of the triceps surae are associated with the individual variability and sex difference in dorsiflexion ROM, using ultrasound shear wave elastography. For men, ROM was negatively correlated to passive muscle stiffness of the medial and lateral gastrocnemius in a tensioned state and positively to tolerance to muscle stretch in the medial gastrocnemius. For women, ROM was only positively correlated to tolerance to muscle stretch in all muscles but not correlated to passive muscle stiffness. Muscle slack angle was not correlated to ROM in men and women. Significant sex differences were observed only for dorsiflexion ROM and passive muscle stiffness in a tensioned state. These findings suggest that muscular factors associated with ROM are different between men and women. Furthermore, the sex difference in dorsiflexion ROM might be attributed partly to that in passive muscle stiffness of plantar flexors.

  4. Presteady-state and steady-state kinetic properties of human cytochrome c oxidase. Identification of rate-limiting steps in mammalian cytochrome c oxidase

    NARCIS (Netherlands)

    van Kuilenburg, A. B.; Gorren, A. C.; Dekker, H. L.; Nieboer, P.; van Gelder, B. F.; Muijsers, A. O.

    1992-01-01

    Human cytochrome c oxidase was purified in a fully active form from heart and skeletal muscle. The enzyme was selectively solubilised with octylglucoside and KCl from submitochondrial particles followed by ammonium sulphate fractionation. The presteady-state and steady-state kinetic properties of

  5. Nonlinear Kinetics on Lattices Based on the Kinetic Interaction Principle

    Directory of Open Access Journals (Sweden)

    Giorgio Kaniadakis

    2018-06-01

    Full Text Available Master equations define the dynamics that govern the time evolution of various physical processes on lattices. In the continuum limit, master equations lead to Fokker–Planck partial differential equations that represent the dynamics of physical systems in continuous spaces. Over the last few decades, nonlinear Fokker–Planck equations have become very popular in condensed matter physics and in statistical physics. Numerical solutions of these equations require the use of discretization schemes. However, the discrete evolution equation obtained by the discretization of a Fokker–Planck partial differential equation depends on the specific discretization scheme. In general, the discretized form is different from the master equation that has generated the respective Fokker–Planck equation in the continuum limit. Therefore, the knowledge of the master equation associated with a given Fokker–Planck equation is extremely important for the correct numerical integration of the latter, since it provides a unique, physically motivated discretization scheme. This paper shows that the Kinetic Interaction Principle (KIP that governs the particle kinetics of many body systems, introduced in G. Kaniadakis, Physica A 296, 405 (2001, univocally defines a very simple master equation that in the continuum limit yields the nonlinear Fokker–Planck equation in its most general form.

  6. A kinetics database and scripts for PHREEQC

    Science.gov (United States)

    Hu, B.; Zhang, Y.; Teng, Y.; Zhu, C.

    2017-12-01

    Kinetics of geochemical reactions has been increasingly used in numerical models to simulate coupled flow, mass transport, and chemical reactions. However, the kinetic data are scattered in the literature. To assemble a kinetic dataset for a modeling project is an intimidating task for most. In order to facilitate the application of kinetics in geochemical modeling, we assembled kinetics parameters into a database for the geochemical simulation program, PHREEQC (version 3.0). Kinetics data were collected from the literature. Our database includes kinetic data for over 70 minerals. The rate equations are also programmed into scripts with the Basic language. Using the new kinetic database, we simulated reaction path during the albite dissolution process using various rate equations in the literature. The simulation results with three different rate equations gave difference reaction paths at different time scale. Another application involves a coupled reactive transport model simulating the advancement of an acid plume in an acid mine drainage site associated with Bear Creek Uranium tailings pond. Geochemical reactions including calcite, gypsum, and illite were simulated with PHREEQC using the new kinetic database. The simulation results successfully demonstrated the utility of new kinetic database.

  7. Partial muscle carnitine palmitoyltransferase-A deficiency

    International Nuclear Information System (INIS)

    Ross, N.S.; Hoppel, C.L.

    1987-01-01

    After initiation of ibuprofen therapy, a 45-year-old woman developed muscle weakness and tenderness with rhabdomyolysis, culminating in respiratory failure. A muscle biopsy specimen showed a vacuolar myopathy, and markedly decreased muscle carnitine content and carnitine palmitoyltransferase activity. Following recovery, muscle carnitine content was normal but carnitine palmitoyltransferase activity was still abnormally low. The ratio of palmitoyl-coenzyme A plus carnitine to palmitoylcarnitine oxidation by muscle mitochondria isolated from the patient was markedly decreased. The authors conclude that transiently decreased muscle carnitine content interacted with partial deficiency of carnitine palmitoyltransferase-A to produce rhabdomyolysis and respiratory failure and that ibuprofen may have precipitated the clinical event

  8. Partial muscle carnitine palmitoyltransferase-A deficiency

    Energy Technology Data Exchange (ETDEWEB)

    Ross, N.S.; Hoppel, C.L.

    1987-01-02

    After initiation of ibuprofen therapy, a 45-year-old woman developed muscle weakness and tenderness with rhabdomyolysis, culminating in respiratory failure. A muscle biopsy specimen showed a vacuolar myopathy, and markedly decreased muscle carnitine content and carnitine palmitoyltransferase activity. Following recovery, muscle carnitine content was normal but carnitine palmitoyltransferase activity was still abnormally low. The ratio of palmitoyl-coenzyme A plus carnitine to palmitoylcarnitine oxidation by muscle mitochondria isolated from the patient was markedly decreased. The authors conclude that transiently decreased muscle carnitine content interacted with partial deficiency of carnitine palmitoyltransferase-A to produce rhabdomyolysis and respiratory failure and that ibuprofen may have precipitated the clinical event.

  9. Torsional carbon nanotube artificial muscles.

    Science.gov (United States)

    Foroughi, Javad; Spinks, Geoffrey M; Wallace, Gordon G; Oh, Jiyoung; Kozlov, Mikhail E; Fang, Shaoli; Mirfakhrai, Tissaphern; Madden, John D W; Shin, Min Kyoon; Kim, Seon Jeong; Baughman, Ray H

    2011-10-28

    Rotary motors of conventional design can be rather complex and are therefore difficult to miniaturize; previous carbon nanotube artificial muscles provide contraction and bending, but not rotation. We show that an electrolyte-filled twist-spun carbon nanotube yarn, much thinner than a human hair, functions as a torsional artificial muscle in a simple three-electrode electrochemical system, providing a reversible 15,000° rotation and 590 revolutions per minute. A hydrostatic actuation mechanism, as seen in muscular hydrostats in nature, explains the simultaneous occurrence of lengthwise contraction and torsional rotation during the yarn volume increase caused by electrochemical double-layer charge injection. The use of a torsional yarn muscle as a mixer for a fluidic chip is demonstrated.

  10. Vitamin D and muscle function.

    Science.gov (United States)

    Dawson-Hughes, Bess

    2017-10-01

    Muscle weakness is a hallmark of severe vitamin D deficiency, but the effect of milder vitamin D deficiency or insufficiency on muscle mass and performance and risk of falling is uncertain. In this presentation, I review the evidence that vitamin D influences muscle mass and performance, balance, and risk of falling in older adults. Special consideration is given to the impact of both the starting 25-hydroxyvitamin D [25(OH)D] level and the dose administered on the clinical response to supplemental vitamin D in older men and women. Based on available evidence, older adults with serum 25(OH)D levels vitamin D dose range of 800-1000 IU per day has been effective in many studies; lower doses have generally been ineffective and several doses above this range have increased the risk of falls. In conclusion, older adults with serum 25(OH)D levels vitamin D. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Muscle after spinal cord injury

    DEFF Research Database (Denmark)

    Biering-Sørensen, Bo; Kristensen, Ida Bruun; Kjaer, Michael

    2009-01-01

    years after the injury. There is a progressive drop in the proportion of slow myosin heavy chain (MHC) isoform fibers and a rise in the proportion of fibers that coexpress both the fast and slow MHC isoforms. The oxidative enzymatic activity starts to decline after the first few months post-SCI. Muscles......The morphological and contractile changes of muscles below the level of the lesion after spinal cord injury (SCI) are dramatic. In humans with SCI, a fiber-type transformation away from type I begins 4-7 months post-SCI and reaches a new steady state with predominantly fast glycolytic IIX fibers...... from individuals with chronic SCI show less resistance to fatigue, and the speed-related contractile properties change, becoming faster. These findings are also present in animals. Future studies should longitudinally examine changes in muscles from early SCI until steady state is reached in order...

  12. Muscle Strength and Poststroke Hemiplegia

    DEFF Research Database (Denmark)

    Kristensen, Otto H; Stenager, Egon; Dalgas, Ulrik

    2017-01-01

    undergone peer review; and (4) were available in English or Danish. DATA EXTRACTION: The psychometric properties of isokinetic dynamometry were reviewed with respect to reliability, validity, and responsiveness. Furthermore, comparisons of strength between paretic, nonparetic, and comparable healthy muscles...... isokinetic dynamometry. DATA SOURCES: A systematic literature search of 7 databases was performed. STUDY SELECTION: Included studies (1) enrolled participants with definite poststroke hemiplegia according to defined criteria; (2) assessed muscle strength or power by criterion isokinetic dynamometry; (3) had...... were reviewed. DATA SYNTHESIS: Twenty studies covering 316 PPSH were included. High intraclass correlation coefficient (ICC) inter- and intrasession reliability was reported for isokinetic dynamometry, which was independent of the tested muscle group, contraction mode, and contraction velocity...

  13. Kinetic model building using advanced nuclear medicine techniques: the kinetics of chromium(III) in the human body

    International Nuclear Information System (INIS)

    Lim, T.H.

    1978-06-01

    The purpose of this study is to investigate whether a valid index of chromium (III) nutritional status can be determined with satisfaction through in vivo kinetic analysis. Three normal subjects and three patients suffering from hemochromatosis were periodically scanned with the Donner Laboratory computerized whole body scanners, starting seconds after radiochromium(III) was administered intravenously, up to a period of 84 days. The activity in the liver, adipose and muscle tissues, spleen and bone was quantitated and corrected, by subtraction of the blood circulation activity in that organ; the major concentration was found in the liver and spleen. From the series of scan images, a kinetic model for the radiochromium(III) metabolic pathway was constructed. Computer analysis showed a significant difference between the two classes of subjects in organs as well as whole body radiochromium(III) transfer. Interpretation of these results showed that in patients with excessive iron stores, a smaller amount of chromium bound to plasma protein was found and a corresponding decrease in transfer of chromium into stores in the liver and other tissues was also found

  14. Development and production of an oligonucleotide MuscleChip: use for validation of ambiguous ESTs

    Directory of Open Access Journals (Sweden)

    Lanfranchi Gerolamo

    2002-10-01

    Full Text Available Abstract Background We describe the development, validation, and use of a highly redundant 120,000 oligonucleotide microarray (MuscleChip containing 4,601 probe sets representing 1,150 known genes expressed in muscle and 2,075 EST clusters from a non-normalized subtracted muscle EST sequencing project (28,074 EST sequences. This set included 369 novel EST clusters showing no match to previously characterized proteins in any database. Each probe set was designed to contain 20–32 25 mer oligonucleotides (10–16 paired perfect match and mismatch probe pairs per gene, with each probe evaluated for hybridization kinetics (Tm and similarity to other sequences. The 120,000 oligonucleotides were synthesized by photolithography and light-activated chemistry on each microarray. Results Hybridization of human muscle cRNAs to this MuscleChip (33 samples showed a correlation of 0.6 between the number of ESTs sequenced in each cluster and hybridization intensity. Out of 369 novel EST clusters not showing any similarity to previously characterized proteins, we focused on 250 EST clusters that were represented by robust probe sets on the MuscleChip fulfilling all stringent rules. 102 (41% were found to be consistently "present" by analysis of hybridization to human muscle RNA, of which 40 ESTs (39% could be genome anchored to potential transcription units in the human genome sequence. 19 ESTs of the 40 ESTs were furthermore computer-predicted as exons by one or more than three gene identification algorithms. Conclusion Our analysis found 40 transcriptionally validated, genome-anchored novel EST clusters to be expressed in human muscle. As most of these ESTs were low copy clusters (duplex and triplex in the original 28,000 EST project, the identification of these as significantly expressed is a robust validation of the transcript units that permits subsequent focus on the novel proteins encoded by these genes.

  15. Ground reaction forces, kinematics, and muscle activations during the windmill softball pitch.

    Science.gov (United States)

    Oliver, Gretchen D; Plummer, Hillary

    2011-07-01

    The aims of the present study were to examine quantitatively ground reaction forces, kinematics, and muscle activations during the windmill softball pitch, and to determine relationships between knee valgus and muscle activations, ball velocity and muscle activation as well as ball velocity and ground reaction forces. It was hypothesized that there would be an inverse relationship between degree of knee valgus and muscle activation, a direct relationship between ground reaction forces and ball velocity, and non-stride leg muscle activations and ball velocity. Ten female windmill softball pitchers (age 17.6 ± 3.47 years, stature 1.67 ± 0.07 m, weight 67.4 ± 12.2 kg) participated. Dependent variables were ball velocity, surface electromyographic (sEMG), kinematic, and kinetic data while the participant was the independent variable. Stride foot contact reported peak vertical forces of 179% body weight. There were positive relationships between ball velocity and ground reaction force (r = 0.758, n = 10, P = 0.029) as well as ball velocity and non-stride leg gluteus maximus (r = 0.851, n = 10, P = 0.007) and medius (r = 0.760, n = 10, P = 0.029) muscle activity, while there was no notable relationship between knee valgus and muscle activation. As the windmill softball pitcher increased ball velocity, her vertical ground reaction forces also increased. Proper conditioning of the lumbopelvic-hip complex, including the gluteals, is essential for injury prevention. From the data presented, it is evident that bilateral strength and conditioning of the gluteal muscle group is salient in the windmill softball pitch as an attempt to decrease incidence of injury.

  16. Thermodynamic basis for cluster kinetics

    DEFF Research Database (Denmark)

    Hu, Lina; Bian, Xiufang; Qin, Xubo

    2006-01-01

    Due to the inaccessibility of the supercooled region of marginal metallic glasses (MMGs) within the experimental time window, we study the cluster kinetics above the liquidus temperature, Tl, to acquire information on the fragility of the MMG systems. Thermodynamic basis for the stability...... of locally ordered structure in the MMG liquids is discussed in terms of the two-order-parameter model. It is found that the Arrhenius activation energy of clusters, h, is proportional to the chemical mixing enthalpy of alloys, Hchem. Fragility of the MMG forming liquids can be described by the ratio...

  17. Kinetics of heterogeneous catalytic reactions

    CERN Document Server

    Boudart, Michel

    2014-01-01

    This book is a critical account of the principles of the kinetics of heterogeneous catalytic reactions in the light of recent developments in surface science and catalysis science. Originally published in 1984. The Princeton Legacy Library uses the latest print-on-demand technology to again make available previously out-of-print books from the distinguished backlist of Princeton University Press. These paperback editions preserve the original texts of these important books while presenting them in durable paperback editions. The goal of the Princeton Legacy Library is to vastly increase acc

  18. Kinetic equations with pairing correlations

    International Nuclear Information System (INIS)

    Fauser, R.

    1995-12-01

    The Gorkov equations are derived for a general non-equilibrium system. The Gorkov factorization is generalized by the cumulant expansion of the 2-particle correlation and by a generalized Wick theorem in the case of a perturbation expansion. A stationary solution for the Green functions in the Schwinger-Keldysh formalism is presented taking into account pairing correlations. Especially the effects of collisional broadening on the spectral functions and Green functions is discussed. Kinetic equations are derived in the quasi-particle approximation and in the case of particles with width. Explicit expressions for the self-energies are given. (orig.)

  19. Kinetic theory of radiation effects

    International Nuclear Information System (INIS)

    Mansur, L.K.

    1987-01-01

    To help achieve the quantitative and mechanistic understanding of these processes, the kinetic theory of radiation effects has been developed in the DOE basic energy sciences radiation effects and fusion reactor materials programs, as well as in corresponding efforts in other countries. This discipline grapples with a very wide range of phenomena and draws on numerous sub-fields of theory such as defect physics, diffusion, elasticity, chemical reaction rates, phase transformations and thermodynamics. The theory is cast in a mathematical framework of continuum dynamics. Issues particularly relevant to the present inquiry can be viewed from the standpoints of applications of the theory and areas requiring further progress

  20. Measurement of contractile stress generated by cultured rat muscle on silicon cantilevers for toxin detection and muscle performance enhancement.

    Directory of Open Access Journals (Sweden)

    Kerry Wilson

    2010-06-01

    Full Text Available To date, biological components have been incorporated into MEMS devices to create cell-based sensors and assays, motors and actuators, and pumps. Bio-MEMS technologies present a unique opportunity to study fundamental biological processes at a level unrealized with previous methods. The capability to miniaturize analytical systems enables researchers to perform multiple experiments in parallel and with a high degree of control over experimental variables for high-content screening applications.We have demonstrated a biological microelectromechanical system (BioMEMS based on silicon cantilevers and an AFM detection system for studying the physiology and kinetics of myotubes derived from embryonic rat skeletal muscle. It was shown that it is possible to interrogate and observe muscle behavior in real time, as well as selectively stimulate the contraction of myotubes with the device. Stress generation of the tissue was estimated using a modification of Stoney's equation. Calculated stress values were in excellent agreement with previously published results for cultured myotubes, but not adult skeletal muscle. Other parameters such as time to peak tension (TPT, the time to half relaxation ((1/2RT were compared to the literature. It was observed that the myotubes grown on the BioMEMS device, while generating stress magnitudes comparable to those previously published, exhibited slower TPT and (1/2RT values. However, growth in an enhanced media increased these values. From these data it was concluded that the myotubes cultured on the cantilevers were of an embryonic phenotype. The system was also shown to be responsive to the application of a toxin, veratridine.The device demonstrated here will provide a useful foundation for studying various aspects of muscle physiology and behavior in a controlled high-throughput manner as well as be useful for biosensor and drug discovery applications.

  1. Muscle GLUT4 in cirrhosis

    DEFF Research Database (Denmark)

    Holland-Fischer, Peter; Andersen, Per Heden; Lund, Sten

    2007-01-01

    test and later a muscle biopsy. Levels of GLUT4 total protein and mRNA content were determined in muscle biopsies by polyclonal antibody labelling and RT-PCR, respectively. RESULTS: GLUT4 protein content in the cirrhosis group was not different from that of the controls, but at variance......: In cirrhosis GLUT4 protein content was quantitatively intact, while limiting glucose tolerance. This indicates loss of redundancy of the major glucose transport system, possibly related to the markedly decreased expression of its gene. Hyper-insulinemia may be a primary event. Our findings implicate...

  2. Muscle assembly: a titanic achievement?

    Science.gov (United States)

    Gregorio, C C; Granzier, H; Sorimachi, H; Labeit, S

    1999-02-01

    The formation of perfectly aligned myofibrils in striated muscle represents a dramatic example of supramolecular assembly in eukaryotic cells. Recently, considerable progress has been made in deciphering the roles that titin, the third most abundant protein in muscle, has in this process. An increasing number of sarcomeric proteins (ligands) are being identified that bind to specific titin domains. Titin may serve as a molecular blueprint for sarcomere assembly and turnover by specifying the precise position of its ligands within each half-sarcomere in addition to functioning as a molecular spring that maintains the structural integrity of the contracting myofibrils.

  3. Radiological diagnostics of muscle diseases

    International Nuclear Information System (INIS)

    Weber, M.A.; Essig, M.; Kauczor, H.U.

    2007-01-01

    Muscular diseases are a heterogeneous group of diseases with difficult differential diagnosis. This article reviews morphological and functional radiological techniques for assessment of muscular diseases. Morphological techniques can describe edema-like changes, lipomatous and atrophic changes of muscular tissue. However, these imaging signs are often not disease-specific. As a result, clinicians assign radiology a secondary role in the management of muscular diseases. Meanwhile, functional radiological techniques allow the assessment of muscle fiber architecture, skeletal muscle perfusion, myocellular sodium-homoeostasis, lipid- and energy-phosphate metabolism, etc. By detecting and spatially localizing pathophysiological phenomena, these new techniques can increase the role of radiology in muscular diseases. (orig.)

  4. Muscle phosphoglycerate mutase deficiency revisited

    DEFF Research Database (Denmark)

    Naini, Ali; Toscano, Antonio; Musumeci, Olimpia

    2009-01-01

    storage disease type X and novel mutations in the gene encoding the muscle subunit of PGAM (PGAM2). DESIGN: Clinical, pathological, biochemical, and molecular analyses. SETTING: Tertiary care university hospitals and academic institutions. Patients A 37-year-old Danish man of Pakistani origin who had...... PGAM deficiency, and molecular studies revealed 2 novel homozygous mutations, a nonsense mutation and a single nucleotide deletion. Pathological studies of muscle showed mild glycogen accumulation but prominent tubular aggregates in both patients. CONCLUSIONS: We found that glycogen storage disease...

  5. The arrangement of muscle fibers and tendons in two muscles used for growth studies.

    Science.gov (United States)

    Stickland, N C

    1983-01-01

    The arrangement of muscle fibres and tendons was examined in the soleus muscle of rats from 6 to 175 days post partum. The muscle was seen to change from a simple structure, with mean fibre length of approximately 90% of complete muscle length, to a unipennate structure, with mean fibre length of only about 60% of muscle length. The dog pectineus muscle was also investigated and found to have a bipennate structure throughout postnatal growth. The arrangement of muscle fibres in both these muscles is such that it might be difficult (particularly in the older animals) to cut a transverse section through all the fibres contained in the muscle; some fibres might not enter the plane of section. Results on muscle fibre number in these muscles at different ages may therefore be misleading.

  6. Novel biomarkers of changes in muscle mass or muscle pathology

    DEFF Research Database (Denmark)

    Arvanitidis, Athanasios

    healthy individuals and patients with different myopathy diseases, describe the underlying mechanisms of muscle conditions and possibly putative response to an intervention. There were three different studies where biomarkers were applied in this thesis. Study I involved 51 myositis patients (28...

  7. Physical Rehabilitation Improves Muscle Function Following Volumetric Muscle Loss Injury

    Science.gov (United States)

    2014-12-19

    synergistic effect of treadmill running on stem -cell transplantation to heal injured skeletal muscle. Tissue Eng Part A 2010, 16(3):839–849. 20. Brutsaert...U:::-’ 0:: 0 Uninjured Injured Figure 7 c E 14 w cu12 • SED * (/) Cll < 10 ~ ~ 8 c 6 Cll Cl 4 z ..!!! ::> 0 2 0::: u 0 Uninjured Injured

  8. PLASTICITY OF SKELETAL MUSCLE STUDIED BY STEREOLOGY

    Directory of Open Access Journals (Sweden)

    Ida Eržen

    2011-05-01

    Full Text Available The present contribution provides an overview of stereological methods applied in the skeletal muscle research at the Institute of Anatomy of the Medical Faculty in Ljubljana. Interested in skeletal muscle plasticity we studied three different topics: (i expression of myosin heavy chain isoforms in slow and fast muscles under experimental conditions, (ii frequency of satellite cells in young and old human and rat muscles and (iii capillary supply of rat fast and slow muscles. We analysed the expression of myosin heavy chain isoforms within slow rat soleus and fast extensor digitorum longus muscles after (i homotopic and heterotopic transplantation of both muscles, (ii low frequency electrical stimulation of the fast muscle and (iii transposition of the fast nerve to the slow muscle. The models applied were able to turn the fast muscle into a completely slow muscle, but not vice versa. One of the indicators for the regenerative potential of skeletal muscles is its satellite cell pool. The estimated parameters, number of satellite cells per unit fibre length, corrected to the reference sarcomere length (Nsc/Lfib and number of satellite cells per number of nuclei (myonuclei and satellite cell nuclei (Nsc/Nnucl indicated that the frequency of M-cadherin stained satellite cells declines in healthy old human and rat muscles compared to young muscles. To access differences in capillary densities among slow and fast muscles and slow and fast muscle fibres, we have introduced Slicer and Fakir methods, and tested them on predominantly slow and fast rat muscles. Discussing three different topics that require different approach, the present paper reflects the three decades of the development of stereological methods: 2D analysis by simple point counting in the 70's, the disector in the 80's and virtual spatial probes in the 90's. In all methods the interactive computer assisted approach was utilised.

  9. Biceps brachii muscle oxygenation in electrical muscle stimulation.

    Science.gov (United States)

    Muthalib, Makii; Jubeau, Marc; Millet, Guillaume Y; Maffiuletti, Nicola A; Ferrari, Marco; Nosaka, Kazunori

    2010-09-01

    The purpose of this study was to compare between electrical muscle stimulation (EMS) and maximal voluntary (VOL) isometric contractions of the elbow flexors for changes in biceps brachii muscle oxygenation (tissue oxygenation index, TOI) and haemodynamics (total haemoglobin volume, tHb = oxygenated-Hb + deoxygenated-Hb) determined by near-infrared spectroscopy (NIRS). The biceps brachii muscle of 10 healthy men (23-39 years) was electrically stimulated at high frequency (75 Hz) via surface electrodes to evoke 50 intermittent (4-s contraction, 15-s relaxation) isometric contractions at maximum tolerated current level (EMS session). The contralateral arm performed 50 intermittent (4-s contraction, 15-s relaxation) maximal voluntary isometric contractions (VOL session) in a counterbalanced order separated by 2-3 weeks. Results indicated that although the torque produced during EMS was approximately 50% of VOL (P<0.05), there was no significant difference in the changes in TOI amplitude or TOI slope between EMS and VOL over the 50 contractions. However, the TOI amplitude divided by peak torque was approximately 50% lower for EMS than VOL (P<0.05), which indicates EMS was less efficient than VOL. This seems likely because of the difference in the muscles involved in the force production between conditions. Mean decrease in tHb amplitude during the contraction phases was significantly (P<0.05) greater for EMS than VOL from the 10th contraction onwards, suggesting that the muscle blood volume was lower in EMS than VOL. It is concluded that local oxygen demand of the biceps brachii sampled by NIRS is similar between VOL and EMS.

  10. Oxygen Uptake Kinetics Is Slower in Swimming Than Arm Cranking and Cycling during Heavy Intensity

    Science.gov (United States)

    Sousa, Ana; Borrani, Fabio; Rodríguez, Ferran A.; Millet, Grégoire P.

    2017-01-01

    Oxygen uptake (V·O2) kinetics has been reported to be influenced by the activity mode. However, only few studies have compared V·O2 kinetics between activities in the same subjects in which they were equally trained. Therefore, this study compared the V·O2 kinetics response to swimming, arm cranking, and cycling within the same group of subjects within the heavy exercise intensity domain. Ten trained male triathletes (age 23.2 ± 4.5 years; height 180.8 ± 8.3 cm; weight 72.3 ± 6.6 kg) completed an incremental test to exhaustion and a 6-min heavy constant-load test in the three exercise modes in random order. Gas exchange was measured by a breath-by-breath analyzer and the on-transient V·O2 kinetics was modeled using bi-exponential functions. V·O2peak was higher in cycling (65.6 ± 4.0 ml·kg−1·min−1) than in arm cranking or swimming (48.7 ± 8.0 and 53.0 ± 6.7 ml·kg−1·min−1; P kinetics were slower in swimming (τ1 = 31.7 ± 6.2 s) than in arm cranking (19.3 ± 4.2 s; P = 0.001) and cycling (12.4 ± 3.7 s; P = 0.001). The amplitude of the primary component was lower in both arm cranking and swimming (21.9 ± 4.7 and 28.4 ± 5.1 ml·kg−1·min−1) compared with cycling (39.4 ± 4.1 ml·kg−1·min−1; P = 0.001). Although the gain of the primary component was higher in arm cranking compared with cycling (15.3 ± 4.2 and 10.7 ± 1.3 ml·min−1·W−1; P = 0.02), the slow component amplitude, in both absolute and relative terms, did not differ between exercise modes. The slower V·O2 kinetics during heavy-intensity swimming is exercise-mode dependent. Besides differences in muscle mass and greater type II muscle fibers recruitment, the horizontal position adopted and the involvement of trunk and lower-body stabilizing muscles could be additional mechanisms that explain the differences between exercise modalities. PMID:28919863

  11. A kinetic model for hydrodesulfurisation

    Energy Technology Data Exchange (ETDEWEB)

    Sau, M.; Narasimhan, C.S.L.; Verma, R.P. [Indian Oil Corporation Limited, Research and Development Centre, Faridabad (India)

    1997-07-01

    Due to stringent environmental considerations and related insistence on low sulfur fuels, hydrodesulfurisation has emerged as an important component of any refining scheme globally. The process is used ranging from Naphta/Kerosine hydrotreating to heavy oil hydrotreating. Processes such as Deep gas oil desulfurisation aiming at reduction of sulfur levels to less than 500 ppm have emerged as major players in the scenario. Hydrodesulfurisation (HDS) involves parallel desulfurisation of different organo-sulfur compounds present in the complex petroleum mixtures. In order to design, monitor, optimise and control the HDS reactor, it is necessary to have a detailed, yet simple model which follows the reaction chemistry accurately. In the present paper, a kinetic model is presented for HDS using continuum theory of lumping. The sulfur distribution in the reaction mixture is treated as continuum and parallel reaction networks are devised for kinetic modelling using continuum theory of lumping approach. The model based on the above approach follows the HDS chemistry reasonably well and hence the model parameters are almost feed invariant. Methods are also devised to incorporate heat and pressure effects into the model. The model has been validated based on commercial kero-HDS data. It is found that the model predictions agree with the experimental/commercial data. 17 refs.

  12. Kinetic Profiles in NSTX Plasmas

    International Nuclear Information System (INIS)

    Bell, R.E.; LeBlanc, B.P.; Bourdelle, C.; Ernst, D.R.; Fredrickson, E.D.; Gates, D.A.; Hosea, J.C.; Johnson, D.W.; Kaye, S.M.; Maingi, R.; Medley, S.; Menard, J.E.; Mueller, D.; Ono, M.; Paoletti, F.; Peng, M.; Sabbagh, S.A.; Stutman, D.; Swain, D.W.; Synakowski, E.J.; Wilson, J.R.

    2001-01-01

    The National Spherical Torus Experiment (NSTX) is a low aspect ratio (R/a approximately 1.3) device with auxiliary heating from neutral-beam injection (NBI) and high-harmonic fast-wave heating (HHFW). Typical NSTX parameters are R(subscript ''0'') = 85 cm, a = 67 cm, I(subscript ''p'') = 0.7-1.4 MA, B(subscript ''phi'') = 0.25-0.45 T. Three co-directed deuterium neutral-beam sources have injected P(subscript ''NB'') less than or equal to 4.7 MW. HHFW plasmas typically have delivered P(subscript ''RF'') less than or equal to 3 MW. Important to the understanding of NSTX confinement are the new kinetic profile diagnostics: a multi-pulse Thomson scattering system (MPTS) and a charge-exchange recombination spectroscopy (CHERS) system. The MPTS diagnostic currently measures electron density and temperature profiles at 30 Hz at ten spatial locations. The CHERS system has recently become available to measure carbon ion temperature and toroidal flow at 17 radial positions spanning the outer half of the minor radius with 20 msec time resolution during NBI. Experiments conducted during the last year have produced a wide range of kinetic profiles in NSTX. Some interesting examples are presented below

  13. Conformational kinetics of aliphatic tails

    Science.gov (United States)

    Ferrarini, Alberta; Moro, Giorgio; Nordio, Pier Luigi

    The master equation describing the random walk between sites identified with the stable conformers of a chain molecule, represents the extension to the time domain of the Rotational Isomeric State model. The asymptotic analysis of the multidimensional diffusion equation in the continuous torsional variables subjected to the configurational potential, provides a rigorous justification for the discrete models, and it supplies, without resorting to phenomenological parameters, molecular definitions of the kinetic rates for the conformational transitions occurring at each segment of the chain. The coupling between the torsional variables is fully taken into account, giving rise to cooperative effects. A complete calculation of the specific correlation functions which describe the time evolution of the angular functions probed by N.M.R. and dielectric relaxation measurements, has been performed for alkyl chains attached to a massive core. The resulting behaviour has been compared with the decay of trans and gauche populations of specific bonds, expressed in terms of suitable correlation functions whose time integrals lead quite naturally to the definition of effective kinetic constants for the conformational transitions.

  14. Blood-organ transfer kinetics

    International Nuclear Information System (INIS)

    Skrable, K.W.; Chabot, G.E.; French, C.S.; Wrenn, M.E.; Lipsztein, J.; Sasso, T.L.; Durbin, P.W.

    1980-01-01

    Exact and approximate kinetics equations relating to the transfer and elimination of radionuclides from the blood and various organs in the body are presented. These expressions may be used to estimate the instantaneous activity or the total number of disintegrations of a radionuclide in the blood or various organs of reference in the body, hence, also the respective dose rates and doses. The exact kinetics equations may be used to relate measurements of radionuclides in excreta to burdens in the body. They do give better results for exposure intervals long compared to the effective mean lives of the radionuclide in the various organs of reference, and they yield the exact steady state expressions. Fortunately, this condition is often satisfied for the relatively long standard exposure interval of 50 years that is applied to occupational exposure. In addition, the steady state expressions may be used along with metabolic data of the distribution of elements in the body, diet and excreta to estimate values of the rate constants used in both the exact and approximate expressions. A comparison of the exact and approximate expressions is given for the uranium metabolic model of Wrenn et al. and a comparison is made with current ICRP models. (author)

  15. Combustion kinetics and reaction pathways

    Energy Technology Data Exchange (ETDEWEB)

    Klemm, R.B.; Sutherland, J.W. [Brookhaven National Laboratory, Upton, NY (United States)

    1993-12-01

    This project is focused on the fundamental chemistry of combustion. The overall objectives are to determine rate constants for elementary reactions and to elucidate the pathways of multichannel reactions. A multitechnique approach that features three independent experiments provides unique capabilities in performing reliable kinetic measurements over an exceptionally wide range in temperature, 300 to 2500 K. Recent kinetic work has focused on experimental studies and theoretical calculations of the methane dissociation system (CH{sub 4} + Ar {yields} CH{sub 3} + H + Ar and H + CH{sub 4} {yields} CH{sub 3} + H{sub 2}). Additionally, a discharge flow-photoionization mass spectrometer (DF-PIMS) experiment is used to determine branching fractions for multichannel reactions and to measure ionization thresholds of free radicals. Thus, these photoionization experiments generate data that are relevant to both reaction pathways studies (reaction dynamics) and fundamental thermochemical research. Two distinct advantages of performing PIMS with high intensity, tunable vacuum ultraviolet light at the National Synchrotron Light Source are high detection sensitivity and exceptional selectivity in monitoring radical species.

  16. Numerical Simulation of the Kinetic Critical Nucleus

    OpenAIRE

    Sanada, Masaaki; Nishioka, Kazumi; Okada, Masahumi; Maksimov, Igor, L.

    1997-01-01

    Our main interest is to see whether the number density indicates a peak at the kinetically stable critical nucleus due to its kinetical stability. We have numerically calculated the time evolution of the number densities of clusters in the case of water vapor nucleation. We employ the condition in which the difference between the size of the thermodynamic crtitical nucleus and that of the kinetic one is appreciable. The results show that the peak does not appear in the number densities of clu...

  17. The characteristics of a pneumatic muscle

    Directory of Open Access Journals (Sweden)

    Pietrala Dawid

    2017-01-01

    Full Text Available The article presents static and dynamic characteristics of pneumatic muscles. It presents the structure of the laboratory stand used to test pneumatic muscles. It discusses the methodology for determination of static and dynamic characteristics. The paper also illustrates characteristics showing the relationship of pneumatic muscles length and operating pressure, at a constant loading force (isotonic characteristics. It presents characteristics showing the relationship of pneumatic muscles shortening and values of loading forces, at a constant operational pressure (isobaric characteristics. It also shows the dependence of force generated by the muscle on the operating pressure, at a constant value of pneumatic muscles shortening (isometric characteristics. The paper also presents dynamic characteristics of a pneumatic muscle showing the response of an object to a gradual change in the operating pressure, at a constant loading force acting on the pneumatic muscle.

  18. The characteristics of a pneumatic muscle

    Science.gov (United States)

    Pietrala, Dawid

    The article presents static and dynamic characteristics of pneumatic muscles. It presents the structure of the laboratory stand used to test pneumatic muscles. It discusses the methodology for determination of static and dynamic characteristics. The paper also illustrates characteristics showing the relationship of pneumatic muscles length and operating pressure, at a constant loading force (isotonic characteristics). It presents characteristics showing the relationship of pneumatic muscles shortening and values of loading forces, at a constant operational pressure (isobaric characteristics). It also shows the dependence of force generated by the muscle on the operating pressure, at a constant value of pneumatic muscles shortening (isometric characteristics). The paper also presents dynamic characteristics of a pneumatic muscle showing the response of an object to a gradual change in the operating pressure, at a constant loading force acting on the pneumatic muscle.

  19. Bones, Muscles, and Joints: The Musculoskeletal System

    Science.gov (United States)

    ... Skeletal muscles are called striated (pronounced: STRY-ay-ted) because they are made up of fibers that ... blood through your body. When we smile and talk, muscles are helping us communicate, and when we ...

  20. Trichinella spiralis in human muscle (image)

    Science.gov (United States)

    This is the parasite Trichinella spiralis in human muscle tissue. The parasite is transmitted by eating undercooked meats, especially pork. The cysts hatch in the intestines and produce large numbers of larvae that migrate into muscle tissue. The cysts ...

  1. Magnetic resonance imaging of facial muscles

    Energy Technology Data Exchange (ETDEWEB)

    Farrugia, M.E. [Department of Clinical Neurology, University of Oxford, Radcliffe Infirmary, Oxford (United Kingdom)], E-mail: m.e.farrugia@doctors.org.uk; Bydder, G.M. [Department of Radiology, University of California, San Diego, CA 92103-8226 (United States); Francis, J.M.; Robson, M.D. [OCMR, Department of Cardiovascular Medicine, University of Oxford, John Radcliffe Hospital, Oxford (United Kingdom)

    2007-11-15

    Facial and tongue muscles are commonly involved in patients with neuromuscular disorders. However, these muscles are not as easily accessible for biopsy and pathological examination as limb muscles. We have previously investigated myasthenia gravis patients with MuSK antibodies for facial and tongue muscle atrophy using different magnetic resonance imaging sequences, including ultrashort echo time techniques and image analysis tools that allowed us to obtain quantitative assessments of facial muscles. This imaging study had shown that facial muscle measurement is possible and that useful information can be obtained using a quantitative approach. In this paper we aim to review in detail the methods that we applied to our study, to enable clinicians to study these muscles within the domain of neuromuscular disease, oncological or head and neck specialties. Quantitative assessment of the facial musculature may be of value in improving the understanding of pathological processes occurring within facial muscles in certain neuromuscular disorders.

  2. Magnetic resonance imaging of facial muscles

    International Nuclear Information System (INIS)

    Farrugia, M.E.; Bydder, G.M.; Francis, J.M.; Robson, M.D.

    2007-01-01

    Facial and tongue muscles are commonly involved in patients with neuromuscular disorders. However, these muscles are not as easily accessible for biopsy and pathological examination as limb muscles. We have previously investigated myasthenia gravis patients with MuSK antibodies for facial and tongue muscle atrophy using different magnetic resonance imaging sequences, including ultrashort echo time techniques and image analysis tools that allowed us to obtain quantitative assessments of facial muscles. This imaging study had shown that facial muscle measurement is possible and that useful information can be obtained using a quantitative approach. In this paper we aim to review in detail the methods that we applied to our study, to enable clinicians to study these muscles within the domain of neuromuscular disease, oncological or head and neck specialties. Quantitative assessment of the facial musculature may be of value in improving the understanding of pathological processes occurring within facial muscles in certain neuromuscular disorders

  3. Drug-Target Kinetics in Drug Discovery.

    Science.gov (United States)

    Tonge, Peter J

    2018-01-17

    The development of therapies for the treatment of neurological cancer faces a number of major challenges including the synthesis of small molecule agents that can penetrate the blood-brain barrier (BBB). Given the likelihood that in many cases drug exposure will be lower in the CNS than in systemic circulation, it follows that strategies should be employed that can sustain target engagement at low drug concentration. Time dependent target occupancy is a function of both the drug and target concentration as well as the thermodynamic and kinetic parameters that describe the binding reaction coordinate, and sustained target occupancy can be achieved through structural modifications that increase target (re)binding and/or that decrease the rate of drug dissociation. The discovery and deployment of compounds with optimized kinetic effects requires information on the structure-kinetic relationships that modulate the kinetics of binding, and the molecular factors that control the translation of drug-target kinetics to time-dependent drug activity in the disease state. This Review first introduces the potential benefits of drug-target kinetics, such as the ability to delineate both thermodynamic and kinetic selectivity, and then describes factors, such as target vulnerability, that impact the utility of kinetic selectivity. The Review concludes with a description of a mechanistic PK/PD model that integrates drug-target kinetics into predictions of drug activity.

  4. Tantalum high-temperature oxidation kinetics

    International Nuclear Information System (INIS)

    Grigor'ev, Yu.M.; Sarkisyan, A.A.; Merzhanov, A.G.

    1981-01-01

    Kinetics of heat release and scale growth during tantalum oxidation within 650-1300 deg C temperature range in oxygen-containing media is investigated. Kinetic equations and temperature and pressure dependences of constants are ound Applicability of the kinetic Lorie mechanism for the description of the tantalum oxidation kinetics applicably to rapid-passing processes is shown. It is stated that the process rate (reaction ability) is determined by adsorption desorption factors on the external surface of the ''protective'' oxide for the ''linear'' oxidation stage [ru

  5. Multidirectional Artificial Muscles from Nylon.

    Science.gov (United States)

    Mirvakili, Seyed M; Hunter, Ian W

    2017-01-01

    Multidirectional artificial muscles are made from highly oriented nylon filaments. Thanks to the low thermal conductivity of nylon and its anisotropic thermal expansion, bending occurs when a nylon beam is differentially heated. This heat can be generated via a Joule heating mechanism or high power laser pulses. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Muscle strength in myasthenia gravis

    DEFF Research Database (Denmark)

    Cejvanovic, S; Vissing, J

    2014-01-01

    OBJECTIVE: Myasthenia gravis (MG) is characterized by fatigue and fluctuating muscle weakness as a result of impaired neuromuscular transmission (NMT). Although MG is a prototypic fatiguing disorder, little is known about how the condition affects fixed weakness, and if present, whether weakness...

  7. Metabolic Adaptation to Muscle Ischemia

    Science.gov (United States)

    Cabrera, Marco E.; Coon, Jennifer E.; Kalhan, Satish C.; Radhakrishnan, Krishnan; Saidel, Gerald M.; Stanley, William C.

    2000-01-01

    Although all tissues in the body can adapt to varying physiological/pathological conditions, muscle is the most adaptable. To understand the significance of cellular events and their role in controlling metabolic adaptations in complex physiological systems, it is necessary to link cellular and system levels by means of mechanistic computational models. The main objective of this work is to improve understanding of the regulation of energy metabolism during skeletal/cardiac muscle ischemia by combining in vivo experiments and quantitative models of metabolism. Our main focus is to investigate factors affecting lactate metabolism (e.g., NADH/NAD) and the inter-regulation between carbohydrate and fatty acid metabolism during a reduction in regional blood flow. A mechanistic mathematical model of energy metabolism has been developed to link cellular metabolic processes and their control mechanisms to tissue (skeletal muscle) and organ (heart) physiological responses. We applied this model to simulate the relationship between tissue oxygenation, redox state, and lactate metabolism in skeletal muscle. The model was validated using human data from published occlusion studies. Currently, we are investigating the difference in the responses to sudden vs. gradual onset ischemia in swine by combining in vivo experimental studies with computational models of myocardial energy metabolism during normal and ischemic conditions.

  8. Muscle mechanics and neuromuscular control

    NARCIS (Netherlands)

    Hof, AL

    The purpose of this paper is to demonstrate that the properties of the mechanical system, especially muscle elasticity and limb mass, to a large degree determine force output and movement. This makes the control demands of the central nervous system simpler and more robust. In human triceps surae, a

  9. No Muscle Is an Island

    DEFF Research Database (Denmark)

    Kent, Jane A; Ørtenblad, Niels; Hogan, Michael C

    2016-01-01

    Muscle fatigue has been studied with a variety approaches, tools and technologies. The foci of these studies have ranged tremendously, from molecules to the entire organism. Single cell and animal models have been used to gain mechanistic insight into the fatigue process. The theme of this review...

  10. Smooth muscle myosin light chain kinase efficiently phosphorylates serine 15 of cardiac myosin regulatory light chain

    Energy Technology Data Exchange (ETDEWEB)

    Josephson, Matthew P.; Sikkink, Laura A. [Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN 55905 (United States); Penheiter, Alan R. [Molecular Medicine Program, Mayo Clinic, Rochester, MN 55905 (United States); Burghardt, Thomas P., E-mail: burghardt@mayo.edu [Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN 55905 (United States); Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN 55905 (United States); Ajtai, Katalin [Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN 55905 (United States)

    2011-12-16

    Highlights: Black-Right-Pointing-Pointer Cardiac myosin regulatory light chain (MYL2) is phosphorylated at S15. Black-Right-Pointing-Pointer Smooth muscle myosin light chain kinase (smMLCK) is a ubiquitous kinase. Black-Right-Pointing-Pointer It is a widely believed that MYL2 is a poor substrate for smMLCK. Black-Right-Pointing-Pointer In fact, smMLCK efficiently and rapidly phosphorylates S15 in MYL2. Black-Right-Pointing-Pointer Phosphorylation kinetics measured by novel fluorescence method without radioactivity. -- Abstract: Specific phosphorylation of the human ventricular cardiac myosin regulatory light chain (MYL2) modifies the protein at S15. This modification affects MYL2 secondary structure and modulates the Ca{sup 2+} sensitivity of contraction in cardiac tissue. Smooth muscle myosin light chain kinase (smMLCK) is a ubiquitous kinase prevalent in uterus and present in other contracting tissues including cardiac muscle. The recombinant 130 kDa (short) smMLCK phosphorylated S15 in MYL2 in vitro. Specific modification of S15 was verified using the direct detection of the phospho group on S15 with mass spectrometry. SmMLCK also specifically phosphorylated myosin regulatory light chain S15 in porcine ventricular myosin and chicken gizzard smooth muscle myosin (S20 in smooth muscle) but failed to phosphorylate the myosin regulatory light chain in rabbit skeletal myosin. Phosphorylation kinetics, measured using a novel fluorescence method eliminating the use of radioactive isotopes, indicates similar Michaelis-Menten V{sub max} and K{sub M} for regulatory light chain S15 phosphorylation rates in MYL2, porcine ventricular myosin, and chicken gizzard myosin. These data demonstrate that smMLCK is a specific and efficient kinase for the in vitro phosphorylation of MYL2, cardiac, and smooth muscle myosin. Whether smMLCK plays a role in cardiac muscle regulation or response to a disease causing stimulus is unclear but it should be considered a potentially significant

  11. Kinetic compartmental analysis of carnitine metabolism in the human carnitine deficiency syndromes. Evidence for alterations in tissue carnitine transport.

    OpenAIRE

    Rebouche, C J; Engel, A G

    1984-01-01

    The human primary carnitine deficiency syndromes are potentially fatal disorders affecting children and adults. The molecular etiologies of these syndromes have not been determined. In this investigation, we considered the hypothesis that these syndromes result from defective transport of carnitine into tissues, particularly skeletal muscle. The problem was approached by mathematical modeling, by using the technique of kinetic compartmental analysis. A tracer dose of L-[methyl-3H]carnitine wa...

  12. The characteristics of a pneumatic muscle

    OpenAIRE

    Pietrala Dawid

    2017-01-01

    The article presents static and dynamic characteristics of pneumatic muscles. It presents the structure of the laboratory stand used to test pneumatic muscles. It discusses the methodology for determination of static and dynamic characteristics. The paper also illustrates characteristics showing the relationship of pneumatic muscles length and operating pressure, at a constant loading force (isotonic characteristics). It presents characteristics showing the relationship of pneumatic muscles s...

  13. Exercise Promotes Healthy Aging of Skeletal Muscle

    DEFF Research Database (Denmark)

    Cartee, Gregory D; Hepple, Russell T; Bamman, Marcas M

    2016-01-01

    caused by diseases and lifestyle factors. Secondary aging can exacerbate deficits in mitochondrial function and muscle mass, concomitant with the development of skeletal muscle insulin resistance. Exercise opposes deleterious effects of secondary aging by preventing the decline in mitochondrial...... respiration, mitigating aging-related loss of muscle mass and enhancing insulin sensitivity. This review focuses on mechanisms by which exercise promotes "healthy aging" by inducing modifications in skeletal muscle....

  14. Integrated expression analysis of muscle hypertrophy identifies Asb2 as a negative regulator of muscle mass

    Science.gov (United States)

    Davey, Jonathan R.; Watt, Kevin I.; Parker, Benjamin L.; Chaudhuri, Rima; Ryall, James G.; Cunningham, Louise; Qian, Hongwei; Sartorelli, Vittorio; Chamberlain, Jeffrey; James, David E.

    2016-01-01

    The transforming growth factor-β (TGF-β) signaling network is a critical regulator of skeletal muscle mass and function and, thus, is an attractive therapeutic target for combating muscle disease, but the underlying mechanisms of action remain undetermined. We report that follistatin-based interventions (which modulate TGF-β network activity) can promote muscle hypertrophy that ameliorates aging-associated muscle wasting. However, the muscles of old sarcopenic mice demonstrate reduced response to follistatin compared with healthy young-adult musculature. Quantitative proteomic and transcriptomic analyses of young-adult muscles identified a transcription/translation signature elicited by follistatin exposure, which included repression of ankyrin repeat and SOCS box protein 2 (Asb2). Increasing expression of ASB2 reduced muscle mass, thereby demonstrating that Asb2 is a TGF-β network–responsive negative regulator of muscle mass. In contrast to young-adult muscles, sarcopenic muscles do not exhibit reduced ASB2 abundance with follistatin exposure. Moreover, preventing repression of ASB2 in young-adult muscles diminished follistatin-induced muscle hypertrophy. These findings provide insight into the program of transcription and translation events governing follistatin-mediated adaptation of skeletal muscle attributes and identify Asb2 as a regulator of muscle mass implicated in the potential mechanistic dysfunction between follistatin-mediated muscle growth in young and old muscles. PMID:27182554

  15. Muscle fatigue in fibromyalgia is in the brain, not in the muscles

    DEFF Research Database (Denmark)

    Bandak, Elisabeth; Amris, Kirstine; Bliddal, Henning

    2013-01-01

    To investigate relationships between perceived and objectively measured muscle fatigue during exhausting muscle contractions in women with fibromyalgia (FM) compared with healthy controls (HC).......To investigate relationships between perceived and objectively measured muscle fatigue during exhausting muscle contractions in women with fibromyalgia (FM) compared with healthy controls (HC)....

  16. Effect of altering starting length and activation timing of muscle on fiber strain and muscle damage.

    Science.gov (United States)

    Butterfield, Timothy A; Herzog, Walter

    2006-05-01

    Muscle strain injuries are some of the most frequent injuries in sports and command a great deal of attention in an effort to understand their etiology. These injuries may be the culmination of a series of subcellular events accumulated through repetitive lengthening (eccentric) contractions during exercise, and they may be influenced by a variety of variables including fiber strain magnitude, peak joint torque, and starting muscle length. To assess the influence of these variables on muscle injury magnitude in vivo, we measured fiber dynamics and joint torque production during repeated stretch-shortening cycles in the rabbit tibialis anterior muscle, at short and long muscle lengths, while varying the timing of activation before muscle stretch. We found that a muscle subjected to repeated stretch-shortening cycles of constant muscle-tendon unit excursion exhibits significantly different joint torque and fiber strains when the timing of activation or starting muscle length is changed. In particular, measures of fiber strain and muscle injury were significantly increased by altering activation timing and increasing the starting length of the muscle. However, we observed differential effects on peak joint torque during the cyclic stretch-shortening exercise, as increasing the starting length of the muscle did not increase torque production. We conclude that altering activation timing and muscle length before stretch may influence muscle injury by significantly increasing fiber strain magnitude and that fiber dynamics is a more important variable than muscle-tendon unit dynamics and torque production in influencing the magnitude of muscle injury.

  17. Effects of extracts of denervated muscles on the morphology of cultured muscle cells

    NARCIS (Netherlands)

    Hooisma, J.; Krijger, J.de; Groot, D.M.G. de

    1981-01-01

    Previously tropic effects of extracts from whole chick embryos and from innervated muscles on cultured muscle cells were described. The present study demonstrated similar effects of extracts from 10-days denervated chick muscles. Extracts from innervated as well as from denervated muscles

  18. Alterations in Muscle Mass and Contractile Phenotype in Response to Unloading Models: Role of Transcriptional/Pretranslational Mechanisms

    Directory of Open Access Journals (Sweden)

    Kenneth M Baldwin

    2013-10-01

    Full Text Available Skeletal muscle is the largest organ system in mammalian organisms providing postural control and movement patterns of varying intensity. Through evolution, skeletal muscle fibers have evolved into three phenotype clusters defined as a muscle unit which consists of all muscle fibers innervated by a single motoneuron linking varying numbers of fibers of similar phenotype. This fundamental organization of the motor unit reflects the fact that there is a remarkable interdependence of gene regulation between the motoneurons and the muscle mainly via activity-dependent mechanisms. These fiber types can be classified via the primary type of myosin heavy chain (MHC gene expressed in the motor unit. Four MHC gene encoded proteins have been identified in striated muscle: slow type I MHC and three fast MHC types, IIa, IIx, and IIb. These MHCs dictate the intrinsic contraction speed of the myofiber with the type I generating the slowest and IIb the fastest contractile speed. Over the last ~35 years, a large body of knowledge suggests that altered loading state cause both fiber atrophy/wasting and a slow to fast shift in the contractile phenotype in the target muscle(s. Hence, this review will examine findings from three different animal models of unloading: 1 space flight (SF, i.e., microgravity; 2 hindlimb suspension (HS, a procedure that chronically eliminates weight bearing of the lower limbs; and 3 spinal cord isolation (SI, a surgical procedure that eliminates neural activation of the motoneurons and associated muscles while maintaining neurotrophic motoneuron-muscle connectivity. The collective findings demonstrate: 1 all three models show a similar pattern of fiber atrophy with differences mainly in the magnitude and kinetics of alteration; 2 transcriptional/pretranslational processes play a major role in both the atrophy process and phenotype shifts; and 3 signaling pathways impacting these alterations appear to be similar in each of the models

  19. In ovo feeding of creatine pyruvate alters energy reserves, satellite cell mitotic activity and myogenic gene expression of breast muscle in embryos and neonatal broilers.

    Science.gov (United States)

    Zhao, M M; Gao, T; Zhang, L; Li, J L; Lv, P A; Yu, L L; Gao, F; Zhou, G H

    2017-09-01

    We investigated the effects of in ovo feeding (IOF) of creatine pyruvate (CrPyr) on energy reserves, satellite cell mitotic activity (SCMA) and myogenic gene expression in breast muscle of embryos and neonatal broilers. A total of 960 eggs were randomly allocated into three treatments: 1) non-injected control group, 2) saline group injected with 0.6 mL of physiological saline (0.75%), and 3) CrPyr group injected with 0.6 mL of physiological saline (0.75%) containing 12 mg CrPyr/egg at 17.5 d of incubation. After hatching, a total of 120 male chicks were randomly assigned to each treatment group, with eight replicate sets per group. Selected chicks had body BW close to the average of their pooled group. Our results showed that the total and relative breast muscle weights of broilers subjected to CrPyr treatment were higher than those in the control and saline groups on 19 d of incubation (19 E), the day of hatch, 3 and 7 d post-hatch (P creatine concentrations on 19 E, the day of hatch and 3 d post-hatch, the same treatment increased phosphocreatine concentrations on 19 E. Broilers in the CrPyr group showed higher expression of myogenic differentiation 1 (MyoD) (P < 0.05), myogenin and paired box 7 (Pax7), as well as higher index of SCMA on 3 d post-hatch. However, myostatin mRNA expression in CrPyr-treated broilers was down-regulated on 3 d post-hatch (P < 0.05). These results indicated that IOF of CrPyr increased energy reserves of embryos and SCMA of broilers on 3 d post-hatch, which led to enhanced muscle growth in the late embryos and neonatal broilers. Additionally, IOF of CrPyr increased the activity of satellite cells possibly through up-regulating MyoD, myogenin, and Pax7 mRNA expression and down-regulating myostatin mRNA expression. © 2017 Poultry Science Association Inc.

  20. Buckling Pneumatic Linear Actuators Inspired by Muscle

    OpenAIRE

    Yang, Dian; Verma, Mohit Singh; So, Ju-Hee; Mosadegh, Bobak; Keplinger, Christoph; Lee, Benjamin; Khashai, Fatemeh; Lossner, Elton Garret; Suo, Zhigang; Whitesides, George McClelland

    2016-01-01

    The mechanical features of biological muscles are difficult to reproduce completely in synthetic systems. A new class of soft pneumatic structures (vacuum-actuated muscle-inspired pneumatic structures) is described that combines actuation by negative pressure (vacuum), with cooperative buckling of beams fabricated in a slab of elastomer, to achieve motion and demonstrate many features that are similar to that of mammalian muscle.