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Muscle Function (muscle + function)
Kinds of Muscle Function Selected AbstractsSKELETAL MUSCLE FUNCTION: ROLE OF IONIC CHANGES IN FATIGUE, DAMAGE AND DISEASECLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 8 2004DG Allen SUMMARY 1.,Repeated activity of skeletal muscle causes a variety of changes in its properties: muscles become weaker with intense use (fatigue), may feel sore and weak after repeated contractions involving stretch and can degenerate in some disease conditions. The present review considers the role of early ionic changes in the development of each of these conditions. 2.,Single fibre preparations of mouse muscle were used to measure ionic changes following activity induced changes in function. Single fibres were dissected with intact tendons and stimulated to produce force. Fluorescent indicators were microinjected into the fibres to allow simultaneous ionic measurements with determination of mechanical performance. 3.,One theory to explain muscle fatigue is that fatigue is caused by the accumulation of lactic acid, producing an intracellular acidosis that inhibits the myofibrillar proteins. In contrast, we found that during repeated tetani there was little or no pH change, but that failure of calcium release was a major contributor to fatigue. Currently, it is proposed that precipitation of calcium and phosphate in the sarcoplasmic reticulum contributes to the failure of calcium release. 4.,Muscles can be used to shorten and produce force or they can be used to de-accelerate loads (stretched or eccentric contractions). One day after intense exercise involving stretched contractions, muscles are weak, sore and tender, and this damage can take a week to recover. In this condition, sarcomeres are disorganized and there are increases in resting intracellular Ca2+ and Na+. Recently, we demonstrated that the elevation of Na+ occurs through a stretch-activated channel that can be blocked by either gadolinium or streptomycin. Preventing the increase in [Na+]i with gadolinium also prevented part of the muscle weakness after stretched contractions. 5.,Duchenne muscular dystrophy is a lethal degenerative disease of muscles in which the protein dystrophin is absent. Dystrophic muscles are more susceptible to stretch-induced muscle damage and the stretch-activated channel seems to be one pathway for the increases in intracellular Ca2+ and Na+ that are a feature of this disease. We have shown recently that blockers of the stretch-activated channel can minimize some of the short-term damage in muscles from the mdx mouse, which also lacks dystrophin. Currently, we are testing whether blockers of the stretch-activated channels given systemically to mdx mice can protect against some features of the disease. [source] The Role of Cytokines in Regulating Protein Metabolism and Muscle FunctionNUTRITION REVIEWS, Issue 2 2002Elena Zoico M.D. Multiple lines of evidence suggest that cytokines influence different physiologic functions of skeletal muscle cells, including anabolic and catabolic processes and programmed cell death. Cytokines play an important role not only in muscle homeostasis, therefore, but also in the pathogenesis of different relevant clinical conditions characterized by alterations in protein metabolism. Recently discovered cytokines, such as ciliary neurotrophic factor and growth/differentiation factor-8, as well as the more studied tumor necrosis factor-,, interleukin-1, interleukin-6, and the interferons, have been implicated in the regulation of muscle protein turnover. Their postreceptor signaling pathways, proteolytic systems, and the mechanisms of protein synthesis inhibition involved in different catabolic conditions have been partially clarified. Moreover, recent studies have shown that cytokines can directly influence skeletal muscle contractility independent of changes in muscle protein content. Even though several gaps remain in our understanding, these observations may be useful in the development of strategies to control protein metabolism and muscle function in different clinical conditions. [source] Balance assessment in patients with peripheral arthritis: applicability and reliability of some clinical assessmentsPHYSIOTHERAPY RESEARCH INTERNATIONAL, Issue 4 2001Anne Marie Norén MSc PT Abstract Background and Purpose Many individuals with peripheral arthritis blame decreased balance as a reason for limiting their physical activity. It is therefore important to assess and improve their balance. The purpose of the present study was to evaluate the applicability and the reliability of some clinical balance assessment methods for people with arthritis and various degrees of disability. Method To examine the applicability and reliability of balance tests, 65, 19 and 22 patients, respectively, with peripheral arthritis participated in sub-studies investigating the applicability, inter-rater reliability and test,retest stability of the following methods: walking on a soft surface, walking backwards, walking in a figure-of-eight, the balance sub-scale of the Index of Muscle Function (IMF), the Timed Up and Go (TUG) test and the Berg balance scale. Results For patients with moderate disability walking in a figure-of-eight was found to be the most discriminative test, whereas ceiling effects were found for the Berg balance scale. Patients with severe disability were generally able to perform the TUG test and the Berg Balance Scale without ceiling effects. Inter-rater reliability was moderate to high and test,retest stability was satisfactory for all methods assessed. Conclusions Applicable and reliable assessment methods of clinical balance were identified for individuals with moderate and severe disability, whereas more discriminative tests need to be developed for those with limited disability. Copyright © 2001 Whurr Publishers Ltd. [source] Exercise Training Improves Aerobic Capacity and Skeletal Muscle Function in Heart Transplant RecipientsAMERICAN JOURNAL OF TRANSPLANTATION, Issue 4 2009M. Haykowsky The aim of this study was to examine the effects of 12 weeks of supervised aerobic and strength training (SET) versus no-training (NT) on peak aerobic power (VO2peak), submaximal exercise left ventricular (LV) systolic function, peripheral vascular function, lean tissue mass and maximal strength in clinically stable heart transplant recipients (HTR). Forty-three HTR were randomly assigned to 12 weeks of SET (n = 22; age: 57 ± 10 years; time posttransplant: 5.4 ± 4.9 years) or NT (n = 21; age: 59 ± 11 years; time posttransplant: 4.4 ± 3.3 years). The change in VO2peak (3.11 mL/kg/min, 95% CI: 1.2,5.0 mL/kg/min), leg and total lean tissue mass (0.78 kg, 95% CI: 0.31,1.3 kg and 1.34 kg, 95% CI: 0.34,2.3 kg, respectively), chest-press (10.4 kg, 95% CI: 5.2,15.5 kg) and leg-press strength (34.7 kg, 95% CI: 3.7,65.6 kg) were significantly higher after SET versus NT. No significant change was found for submaximal exercise LV systolic function or brachial artery endothelial-dependent or -independent vasodilation. Supervised exercise training is an effective intervention to improve VO2peak, lean tissue mass and muscle strength in HTR. This training regimen did not improve exercise LV systolic function or brachial artery endothelial function. [source] Epigenetic control of skeletal muscle fibre typeACTA PHYSIOLOGICA, Issue 4 2010K. Baar Abstract Adult muscle is extremely plastic. However, the muscle precursor cells associated with those fibres show stable and heritable differences in gene expression indicative of epigenetic imprinting. Epigenetic processes in the development of skeletal muscle have been appreciated for over a decade; however, there are a paucity of studies looking at whether epigenetics determines the phenotype of adult and/or ageing skeletal muscle. This review presents the evidence that epigenetics plays a role in determining adult muscle function and a series of unanswered questions that would greatly increase our understanding of how epigenetics works in adult muscle. With the increased interest in epigenetics, over the next few years this field will begin to unfold in unimaginable directions. [source] The decrease in electrically evoked force production is delayed by a previous bout of stretch,shortening cycle exerciseACTA PHYSIOLOGICA, Issue 1 2010S. Kamandulis Abstract Aim:, Unaccustomed physical exercise with a large eccentric component is accompanied by muscle damage and impaired contractile function, especially at low stimulation frequencies. A repeated bout of eccentric exercise results in less damage and improved recovery of contractile function. Here we test the hypotheses that (1) a prior stretch,shortening cycle (SSC) exercise protects against impaired muscle function during a subsequent bout of SSC exercise and (2) the protection during exercise is transient and becomes less effective as the exercise progresses. Methods:, Healthy untrained men (n = 7) performed SSC exercise consisting of 100 maximal drop jumps at 30 s intervals. The same exercise was repeated 4 weeks later. Peak quadriceps muscle force evoked by electrical stimulation at 15 (P15) and 50 (P50) Hz was measured before exercise, after 10, 25, 50 and 100 jumps as well as 1 and 24 h after exercise. Results:, P15 and P50 were higher during the initial phase of the repeated bout compared with the first exercise bout, but there was no difference between the bouts at the end of the exercise periods. P15 and P50 were again larger 24 h after the repeated bout. The P15/P50 ratio during exercise was not different between the two bouts, but it was higher after the repeated bout. Conclusion:, A prior bout of SSC exercise temporarily protects against impaired contractile function during a repeated exercise bout. The protection can again be seen after exercise, but the underlying mechanism then seems to be different. [source] Androgen replacement therapy improves function in male rat muscles independently of hypertrophy and activation of the Akt/mTOR pathwayACTA PHYSIOLOGICA, Issue 4 2009C. Hourdé Abstract Aim:, We analysed the effect of physiological doses of androgens following orchidectomy on skeletal muscle and bone of male rats, as well as the relationships between muscle performance, hypertrophy and the Akt/mammalian target of rapamycin (mTOR) signalling pathway involved in the control of anabolic and catabolic muscle metabolism. Methods:, We studied the soleus muscle and tibia from intact rats (SHAM), orchidectomized rats treated for 3 months with vehicle (ORX), nandrolone decanoate (NAN) or dihydrotestosterone (DHT). Results:, Orchidectomy had very little effect on the soleus muscle. However, maximal force production by soleus muscle (+69%) and fatigue resistance (+35%) in NAN rats were both increased when compared with ORX rats. In contrast, DHT treatment did not improve muscle function. The relative number of muscle fibres expressing slow myosin heavy chain and citrate synthase activity were not different in NAN and ORX rats. Moreover, NAN and DHT treatments did not modify muscle weights and cross-sectional area of muscle fibres. Furthermore, phosphorylation levels of downstream targets of the Akt/mTOR signalling pathway, Akt, ribosomal protein S6 and eukaryotic initiation factor 4E-binding protein 1 were similar in muscles of NAN, DHT and ORX rats. In addition, trabecular tibia from NAN and DHT rats displayed higher bone mineral density and bone volume when compared with ORX rats. Only in NAN rats was this associated with increased bone resistance to fracture. Conclusion:, Physiological doses of androgens are beneficial to muscle performance in orchidectomized rats without relationship to muscle and fibre hypertrophy and activation of the Akt/mTOR signalling pathway. Taken together our data clearly indicate that the activity of androgens on muscle and bone could participate in the global improvement of musculoskeletal status in the context of androgen deprivation induced by ageing. [source] Acute effects of desmin mutations on cytoskeletal and cellular integrity in cardiac myocytesCYTOSKELETON, Issue 2 2003Kurt Haubold Mutations in desmin have been associated with a subset of human myopathies. Symptoms typically appear in the second to third decades of life, but in the most severe cases can manifest themselves earlier. How desmin mutations lead to aberrant muscle function, however, remains poorly defined. We created a series of four mutations in rat desmin and tested their in vitro filament assembly properties. RDM-G, a chimera between desmin and green fluorescent protein, formed protofilament-like structures in vitro. RDM-1 and RDM-2 blocked in vitro assembly at the unit-length filament stage, while RDM-3 had more subtle effects on assembly. When expressed in cultured rat neonatal cardiac myocytes via adenovirus infection, these mutant proteins disrupted the endogenous desmin filament to an extent that correlated with their defects in in vitro assembly properties. Disruption of the desmin network by RDM-1 was also associated with disruption of plectin, myosin, and ,-actinin organization in a significant percentage of infected cells. In contrast, expression of RDM-2, which is similar to previously characterized human mutant desmins, took longer to disrupt desmin and plectin organization and had no significant effect on myosin or ,-actinin organization over the 5-day time course of our studies. RDM-3 had the mildest effect on in vitro assembly and no discernable effect on either desmin, plectin, myosin, or ,-actinin organization in vivo. These results indicate that mutations in desmin have both direct and indirect effects on the cytoarchitecture of cardiac myocytes. Cell Motil. Cytoskeleton 54:105,121, 2003. © 2003 Wiley-Liss, Inc. [source] Modified Von Bruns' Technique for Total Lower Lip ReconstructionDERMATOLOGIC SURGERY, Issue 3 2004Neta Adler MD Background. Large defects of the lower lip represent a challenge to the reconstructive surgeon. The reconstructed lip should be sensate, retain muscle function, allow sufficient mouth opening for dentures, and have an acceptable aesthetic appearance. Many surgical techniques for lower lip reconstruction have been reported. We describe a modification of von Bruns' technique for reconstruction of the lower lip and both commissures. Objective. To present a surgical technique for reconstruction of the lower lip and both commissures, which we applied in a patient with a huge squamous cell carcinoma of the total lower lip and part of the upper lip. Methods. Two upper nasolabial flaps, one above the other, were used. The surgical technique is discussed. Conclusion. The technique is simple and is one stage. It provides complete support to the reconstructed lower lip and commissures. [source] Screening for the calstabin-ryanodine receptor complex stabilizers JTV-519 and S-107 in doping control analysisDRUG TESTING AND ANALYSIS, Issue 1 2009Mario Thevis Abstract Recent studies outlined the influence of exercise on the stability of the skeletal muscle calstabin1-ryanodine receptor1-complex, which represents a major Ca2+ release channel. The progressive modification of the type-1 skeletal muscle ryanodine receptor (RyR1) combined with reduced levels of calstabin1 and phosphodiesterase PDE4D3 resulted in a Ca2+ leak that has been a suggested cause of muscle damage and impaired exercise capacity. The use of 1,4-benzothiazepine derivatives such as the drug candidates JTV-519 and S-107 enhanced rebinding of calstabin1 to RyR1 and resulted in significantly improved skeletal muscle function and exercise performance in rodents. Due to the fact that the mechanism of RyR1 remodelling under exercise conditions were proven to be similar in mice and humans, a comparable effect of JTV-519 and S-107 on trained athletes is expected, making the compounds relevant for doping controls. After synthesis of JTV-519, S-107, and a putative desmethylated metabolite of S-107, target compounds were characterized using nuclear magnetic resonance spectroscopy and electrospray ionization (ESI),high-resolution/high-accuracy Orbitrap mass spectrometry. Collision-induced dissociation pathways were suggested based on the determination of elemental compositions of product ions and H/D-exchange experiments. The most diagnostic product ion of JTV-519 was found at m/z 188 (representing the 4-benzyl-1-methyl piperidine residue), and S-107 as well as its desmethylated analog yielded characteristic fragments at m/z 153 and 138 (accounting for 1-methoxy-4-methylsulfanyl-benzene and 4-methoxy-benzenethiol residues, respectively). The analytes were implemented in existing doping control screening procedures based on liquid chromatography, multiple reaction monitoring and simultaneous precursor ion scanning modes using a triple quadrupole mass spectrometer. Validation items such as specificity, recovery (68,92%), lower limit of detection (0.1,0.2 ng/mL), intraday (5.2,18.5%) and interday (8.7,18.8%) precision as well as ion suppression/enhancement effects were determined. Copyright © 2009 John Wiley & Sons, Ltd. [source] In vitro effects of lidocaine on the contractility of equine jejunal smooth muscle challenged by ischaemia-reperfusion injuryEQUINE VETERINARY JOURNAL, Issue 1 2010M. GUSCHLBAUER Summary Reasons for performing study: Post operative ileus (POI) in horses is a severe complication after colic surgery. A commonly used prokinetic drug is lidocaine, which has been shown to have stimulatory effects on intestinal motility. The cellular mechanisms through which lidocaine affects smooth muscle activity are not yet known. Objectives: To examine the effects of lidocaine on smooth muscle in vitro and identify mechanisms by which it may affect the contractility of intestinal smooth muscle. Hypothesis: Ischaemia and reperfusion associated with intestinal strangulation can cause smooth muscle injury. Consequently, muscle cell functionality and contractile performance is decreased. Lidocaine can improve basic cell functions and thereby muscle cell contractility especially in ischaemia-reperfusion-challenged smooth muscle. Methods: To examine the effects of lidocaine on smooth muscle function directly, isometric force performance was measured in vitro in noninjured and in vivo ischaemia-reperfusion injured smooth muscle tissues. Dose-dependent response of lidocaine was measured in both samples. To assess membrane permeability as a marker of basic cell function, release of creatine kinase (CK) was measured by in vitro incubations. Results: Lidocaine-stimulated contractility of ischaemia-reperfusion injured smooth muscle was more pronounced than that of noninjured smooth muscle. A 3-phasic dose-dependency was observed with an initial recovery of contractility especially in ischaemia-reperfusion injured smooth muscle followed by a plateau phase where contractility was maintained over a broad concentration range. CK release was decreased by lidocaine. Conclusion: Lidocaine may improve smooth muscle contractility and basic cell function by cellular repair mechanisms which are still unknown. Improving contractility of smooth muscle after ischaemia-reperfusion injury is essential in recovery of propulsive intestinal motility. Potential relevance: Characterisation of the cellular mechanisms of effects of lidocaine, especially on ischaemia-reperfusion injured smooth muscle, may lead to improved treatment strategies for horses with POI. [source] Electromyographic activity of the palatinus and palatopharyngeus muscles in exercising horsesEQUINE VETERINARY JOURNAL, Issue 5 2007S. J. HOLCOMBE Summary Reasons for performing study: Determining the respiratory related activity of the palatinus and palatopharyngeus muscles in exercising horses is relevant because dysfunction of these muscles has been implicated in the pathogenesis of dorsal displacement of the soft palate. Objective: To determine if the palatinus and palatopharyngeus muscles have respiratory activity that increases with intensity in exercising horses. Methods: Electromyographic activity was measured in the palatinus and palatopharyngeus muscles using bipolar fine-wire electrodes while the horses completed an incremental exercise treadmill protocol. Results: Both muscles displayed synchronous expiratory activity that increased significantly (P<0.05) with exercise intensity. Phasic expiratory activity of the palatinus increased 390 ± 98%, whereas phasic expiratory activity of the palatopharyngeus increased by 198 ± 30% as the treadmill speed increased from 6 to 12 m/s. Conclusions: The palatinus and palatopharyngeus muscles may be important respiratory muscles, functioning to stabilise the position of the soft palate during intense exercise. Clinical relevance: The predominant expiratory activity of these muscles may be associated with specific muscle function related to exercise or distinct upper airway phenomena of an obligate nasal breather, such as the horse. [source] Effects of masticatory muscle function on craniofacial morphology in growing ferrets (Mustela putorius furo)EUROPEAN JOURNAL OF ORAL SCIENCES, Issue 6 2003Tailun He Studying the effects of masticatory muscle function on craniofacial morphology in animal models with different masticatory systems is important for further understanding of related issues in humans. Forty 5-wk-old male ferrets were equally divided into two groups. One group was fed a diet of hard pellets (HDG) and the other group was fed the same diet but softened with water (SDG). Lateral and dorsoventral cephalograms were taken on each group after 6 months. Cephalometric measurements were performed by digital procedures. For SDG ferrets, the hard palate plane was more distant from the cranial base plane, and canines were more proclined compared with HDG ferrets. The SDG ferrets were also found to have smaller interfrontal and interparietal widths, and a slenderer zygomatic arch than the HDG ferrets. In the mandible, the coronoid process was generally shorter and narrower for the SDG ferrets. The effects of the altered masticatory muscle function on craniofacial morphology in growing ferrets seemed to differ from those previously reported in other animal models studied under similar experimental conditions. Such differences in the effects are presumably related to the differences in the mode of mastication, craniofacial anatomy and growth pattern in different animal models. [source] Exercise training in late middle-aged male Fischer 344 × Brown Norway F1-hybrid rats improves skeletal muscle aerobic functionEXPERIMENTAL PHYSIOLOGY, Issue 7 2008Andrew C. Betik The Fischer 344 × Brown Norway F1-hybrid (F344BN) rat has become an increasingly popular and useful strain for studying age-related declines in skeletal muscle function because this strain lives long enough to experience significant declines in muscle mass. Since exercise is often considered a mechanism to combat age-related declines in muscle function, determining the utility of this strain of rat for studying the effects of exercise on the ageing process is necessary. The purpose of this study was to evaluate the plasticity of skeletal muscle aerobic function in late middle-aged male rats following 7 weeks of treadmill exercise training. Training consisted of 60 min per day, 5 days per week with velocity gradually increasing over the training period according to the capabilities of individual rats. The final 3 weeks involved 2 min high-intensity intervals to increase the training stimulus. We used in situ skeletal muscle aerobic metabolic responses and in vitro assessment of muscle mitochondrial oxidative capacity to describe the adaptations of aerobic function from the training. Training increased running endurance from 11.3 ± 0.6 to 15.5 ± 0.8 min, an improvement of ,60%. Similarly, distal hindlimb muscles from trained rats exhibited a higher maximal oxygen consumption in situ (23.2 ± 1.3 versus 19.7 ± 0.8 ,mol min,1 for trained versus sedentary rats, respectively) and greater citrate synthase and complex IV enzyme activities in gastrocnemius (29 and 19%, respectively) and plantaris muscles (24 and 28%, respectively) compared with age-matched sedentary control animals. Our results demonstrate that skeletal muscles from late middle-aged rats adapt to treadmill exercise by improving skeletal muscle aerobic function and mitochondrial enzyme activities. This rat strain seems suitable for further investigations using exercise as an intervention to combat ageing-related declines of skeletal muscle aerobic function. [source] Mitochondrial affinity for ADP is twofold lower in creatine kinase knock-out musclesFEBS JOURNAL, Issue 4 2005Possible role in rescuing cellular energy homeostasis 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- and double CK-knock-out mice strains (cytosolic (M-CK,/,), mitochondrial (Mi-CK,/,) and double knock-out (MiM-CK,/,), respectively). Maximal ADP-stimulated oxygen consumption flux (State3 Vmax; nmol O2·mg mitochondrial protein,1·min,1) and ADP affinity (; µm) were determined by respirometry. State 3 Vmax and of M-CK,/, and MiM-CK,/, gastrocnemius mitochondria were twofold higher than those of WT, but were unchanged for Mi-CK,/,. For mutant cardiac mitochondria, only the of mitochondria isolated from the MiM-CK,/, phenotype was different (i.e. twofold higher) than that of WT. The implications of these adaptations for striated muscle function were explored by constructing force-flow relations of skeletal muscle respiration. It was found that the identified shift in affinity towards higher ADP concentrations in MiM-CK,/, muscle genotypes may contribute to linear mitochondrial control of the reduced cytosolic ATP free energy potentials in these phenotypes. [source] Secondary end-to-end repair of extensive facial nerve defects: Surgical technique and postoperative functional resultsHEAD & NECK: JOURNAL FOR THE SCIENCES & SPECIALTIES OF THE HEAD AND NECK, Issue 9 2004Hildegunde Piza-Katzer MD Abstract Background. Repair of the transected facial nerve is imperative for restoration of muscle function, including the ability to produce appropriate facial expressions. Injury might involve the main trunk and its several branches. Restoration of function presupposes meticulous repair of all injured nerve branches. Methods. Here we report three cases of secondary tension-free end-to-end coaptation of a transected trunk and branches of the facial nerve by removal of the superficial part of the parotid gland. Results. Facial tone and symmetry at rest and motion were achieved. In two patients, a slight residual synkinesis is observed under stress. Conclusions. Direct end-to-end coaptation of the facial nerve and its branches by the technique described should be considered before deciding on grafts or rerouting procedures to deal with gaps of up to 15 mm. This technique is not recommended in the presence of infection and nerve defects. Intensive postoperative physiotherapy is required for optimal results. © 2004 Wiley Periodicals, Inc. Head Neck26: 770,777, 2004 [source] Muscle performance in patients with Crohn's disease in clinical remissionINFLAMMATORY BOWEL DISEASES, Issue 3 2005Jean-Baptiste Wiroth PhD Abstract Background: Because patients with Crohn's disease (CD) often show increased energy expenditure, nutritional deficiencies, and general fatigue, all which may persist after a flare, we hypothesized that CD could alter muscle mass and function. This study aimed to assess muscle strength and endurance in CD patients in clinical remission and the influencing factors. Methods: Forty-one outpatients (17 men and 24 women; age, 37 ± 10 yr), in remission (CD Activity Index < 150) for >3 months, and 25 age-matched healthy controls (10 men and 15 women; age, 37 ± 13 yr) were evaluated. Evaluation included a sit-up test, hand-grip strength test, hand-grip endurance test, lower limb strength test, and lower limb endurance test (LE), as well as a measure of physical activity. Results: No significant difference was found between CD and control groups regarding weight, height, body mass index, fat mass, and fat-free mass. Strength performance was lower in CD subjects compared with controls, particularly for lower limb indexes: lower limb strength test (,24.6%, P < 0.001), LE (,25.8%, P < 0.001), and sit-up test (,25.1%, P < 0.001). Previous disease severity, disease duration, the cumulative dose of glucocorticosteroids, current inflammation, and global habitual physical activity did not affect muscle performance. A recent use of steroids improved LE. Conclusions: CD patients in clinical remission have decreased muscle function that may affect their quality of life. This pattern is reflected by reduced strength and endurance indexes, particularly for lower limbs. The reasons for these changes need further study. Strength training should be assessed in these patients. [source] Functional effects of mutations identified in patients with Multiminicore diseaseIUBMB LIFE, Issue 1 2007Francesco Zorzato Abstract Multiminicore disease is a recessive congenital myopathy characterized by the presence of small cores or areas lacking oxidative enzymes, in skeletal muscle fibres. From a clinical point of view, the condition is widely heterogeneous and at least four phenotypes have been identified; genetic analysis has revealed that most patients with the classical form of multiminicore characterized by rigidity of the spine, early onset and respiratory impairment harbour recessive mutations in the SEPN1 gene, whereas the majority of patients belonging to the other categories, including patients with ophthalmoplegia or patients with a phenotype similar to central core disease, carry recessive mutations in the RYR1. In the present review we discuss the most recent findings on the functional effect of mutations in SEPN1 and RYR1 and discuss how they may adversely affect muscle function and lead to the clinical phenotype. IUBMB Life, 59: 14-20, 2007 [source] Diet and Its Relationship with Grip Strength in Community-Dwelling Older Men and Women: The Hertfordshire Cohort StudyJOURNAL OF AMERICAN GERIATRICS SOCIETY, Issue 1 2008Sian M. Robinson PhD OBJECTIVES: To examine relationships between diet and grip strength in older men and women and to determine whether prenatal growth modifies these relationships. DESIGN: Cross-sectional and retrospective cohort study. SETTING: Hertfordshire, United Kingdom. PARTICIPANTS: Two thousand nine hundred eighty-three men and women aged 59 to 73 who were born and still living in Hertfordshire, United Kingdom. MEASUREMENTS: Weight at birth recorded in Health Visitor ledgers; current food and nutrient intake assessed using an administered food frequency questionnaire; and grip strength measured using a handheld dynamometer. RESULTS: Grip strength was positively associated with height and weight at birth and inversely related to age (all P<.001). Of the dietary factors considered in relation to grip strength, the most important was fatty fish consumption. An increase in grip strength of 0.43 kg (95% confidence interval (CI)=0.13,0.74) in men (P=.005) and 0.48 kg (95% CI=0.24,0.72) in women (P<.001) was observed for each additional portion of fatty fish consumed per week. These relationships were independent of adult height, age, and birth weight, each of which had additive effects on grip strength. There was no evidence of interactive effects of weight at birth and adult diet on grip strength. CONCLUSION: These data suggest that fatty fish consumption can have an important influence on muscle function in older men and women. This raises the possibility that the antiinflammatory actions of omega-3 fatty acids may play a role in the prevention of sarcopenia. [source] Intra- and intermuscular variation in human quadriceps femoris architecture assessed in vivoJOURNAL OF ANATOMY, Issue 3 2006Anthony J. Blazevich Abstract Despite the functional importance of the human quadriceps femoris in movements such as running, jumping, lifting and climbing, and the known effects of muscle architecture on muscle function, no research has fully described the complex architecture of this muscle group. We used ultrasound imaging techniques to measure muscle thickness, fascicle angle and fascicle length at multiple regions of the four quadriceps muscles in vivo in 31 recreationally active, but non-strength-trained adult men and women. Our analyses revealed a reasonable similarity in the superficial quadriceps muscles, which is suggestive of functional similarity (at least during the uni-joint knee extension task) given that they act via a common tendon. The deep vastus intermedius (VI) is architecturally dissimilar and therefore probably serves a different function(s). Architecture varies significantly along the length of the superficial muscles, which has implications for the accuracy of models that assume a constant intramuscular architecture. It might also have consequences for the efficiency of intra- and intermuscular force transmission. Our results provide some evidence that subjects with a given architecture of one superficial muscle, relative to the rest of the subject sample, also have a similar architecture in other superficial muscles. However, this is not necessarily true for vastus lateralis (VL), and was not the case for VI. Therefore, the relative architecture of one muscle cannot confidently be used to estimate the relative architecture of another. To confirm this, we calculated a value of whole quadriceps architecture by four different methods. Regardless of the method used, we found that the absolute or relative architecture of one muscle could not be used as an indicator of whole quadriceps architecture, although vastus medialis, possibly in concert with VL and the anterior portion of VI, could be used to provide a useful snapshot. Importantly, our estimates of whole quadriceps architecture show a gender difference in whole quadriceps muscle thickness, and that muscle thickness is positively correlated with fascicle angle whereas fascicle length is negatively, although weakly, correlated with fascicle angle. These results are supportive of the validity of estimates of whole quadriceps architecture. These data are interpreted with respect to their implications for neural control strategies, region-specific adaptations in muscle size in response to training, and gender-dependent differences in the response to exercise training. [source] Therapy of Osteoporosis With Calcium and Vitamin D,JOURNAL OF BONE AND MINERAL RESEARCH, Issue S2 2007Bess Dawson-Hughes MD Abstract Inadequate intakes of vitamin D and calcium lead to reduced calcium absorption, higher bone remodeling rates, and increased bone loss. Vitamin D insufficiency has also been linked to reduced muscle function and increased risk of falling. The mechanisms for the performance and muscle effects are not well understood. Administering vitamin D to those with inadequate vitamin D status has been shown to lower fracture rates in some trials but not in others. The purpose of this presentation is (1) to examine how calcium and vitamin D work in concert, (2) to consider key evidence that increasing vitamin D intake will affect risk of falls and fractures, and (3) to estimate the 25-hydroxyvitamin D [25(OH)D] level needed to achieve maximum fracture protection. [source] Neuromuscular function in healthy occlusionJOURNAL OF ORAL REHABILITATION, Issue 9 2010S. E. FORRESTER Summary, This study aimed to measure neuromuscular function for the masticatory muscles under a range of occlusal conditions in healthy, dentate adults. Forty-one subjects conducted maximum voluntary clenches under nine different occlusal loading conditions encompassing bilateral posterior teeth contacts with the mandible in different positions, anterior teeth contacts and unilateral posterior teeth contacts. Surface electromyography was recorded bilaterally from the anterior temporalis, superficial masseter, sternocleidomastoid, anterior digastric and trapezius muscles. Clench condition had a significant effect on muscle function (P = 0·0000) with the maximum function obtained for occlusions with bilateral posterior contacts and the mandible in a stable centric position. The remaining contact points and moving the mandible to a protruded position, whilst keeping posterior contacts, resulted in significantly lower muscle activities. Clench condition also had a significant effect on the per cent overlap, anterior,posterior and torque coefficients (P = 0·0000,0·0024), which describe the degree of symmetry in these muscle activities. Bilateral posterior contact conditions had significantly greater symmetry in muscle activities than anterior contact conditions. Activity in the sternocleidomastoid, anterior digastric and trapezius was consistently low for all clench conditions, i.e. <20% of the maximum voluntary contraction level. In conclusion, during maximum voluntary clenches in a healthy population, maximum masticatory muscle activity requires bilateral posterior contacts and the mandible to be in a stable centric position, whilst with anterior teeth contacts, both the muscle activity and the degree of symmetry in muscle activity are significantly reduced. [source] Evaluation of a novel biomaterial for intrasubstance muscle laceration repairJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 3 2007Bradley D. Crow Abstract The authors compare the effects of small intestinal submucosa (SIS) treatment to suture repair with respect to histologic and functional outcomes for complete muscle lacerations in a rabbit model. The authors hypothesized that SIS treatment of full-thickness muscle belly lacerations would significantly improve muscle function, strength, and regeneration compared to the current standard-of-care treatment. Muscle belly lacerations were created in the extensor digitorum longus (EDL) of both hind limbs of each rabbit. After randomization, lacerations were left unrepaired (n,=,48) or repaired using a 4-0 Prolene modified Kessler stitch (n,=,48). A flap of SIS graft was sutured into half (n,=,24 each) of the repaired and unrepaired muscles forming four study groups. Suture repair with SIS augmentation of complete muscle lacerations resulted in healed tissue that most closely resembled normal muscle in terms of morphology and function when compared to current standard-of-care treatments. Active force production in this group reached 79% of uninjured controls 12 weeks after surgery. SIS may have important clinical advantages over suture repair alone and warrants further clinical study. © 2006 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 2007 [source] NO message from muscleMICROSCOPY RESEARCH AND TECHNIQUE, Issue 3 2001Zarko Grozdanovic Abstract The synthesis of the free radical gas nitric oxide (NO) is catalyzed by the enzyme NO synthase (NOS). NOS converts arginine and molecular oxygen to NO and citrulline in a reaction that requires NADPH, FAD, FMN, and tetrahydrobiopterin as cofactors. Three types of NOS have been identified by molecular cloning. The activity of the constitutively expressed neuronal NOS (nNOS) and endothelial NOS (eNOS) is Ca2+/calmodulin-dependent, whereas that the inducible NOS (iNOS) is Ca2+ -insensitive. The predominant NOS isoform in skeletal muscle is nNOS. It is present at the sarcolemma of both extra- and intrafusal muscle fibers. An accentuated accumulation of nNOS is found in the endplate area. This strict sarcolemmal localization of nNOS is due its association with the dystrophin-glycoprotein complex, which is mediated by the syntrophins. The activity of nNOS in skeletal muscle is regulated by developmental, myogenic, and neurogenic influences. NO exerts several distinct effects on various aspects of skeletal muscle function, such as excitation-contraction coupling, mitochondrial energy production, glucose metabolism, and autoregulation of blood flow. Inside the striated muscle fibers, NO interacts directly with several classes of proteins, such as soluble guanylate cyclase, ryanodine receptor, sarcoplasmic reticulum Ca2+ -ATPase, glyceraldehyde-3-phosphate dehydrogenase, and mitochondrial respiratory chain complexes, as well as radical oxygen species. In addition, NO produced and released by contracting muscle fibers diffuses to nearby arterioles where it acts to inhibit reflex sympathetic vasoconstriction. Microsc. Res. Tech. 55:148,153, 2001. © 2001 Wiley-Liss, Inc. [source] Effect of HTK on the microcirculation in the rat cremaster muscle during warm ischemia and reperfusionMICROSURGERY, Issue 2 2005Jacqueline Bastiaanse M.D. Histidine-tryptophan-ketoglutarate (HTK) preserves rat muscle function during cold storage. We examined the effect of HTK perfusion on preservation of microvascular function during 4 h of warm ischemia and subsequent reperfusion (I/R) in the rat cremaster muscle. Leukocyte-endothelium interactions, capillary perfusion, and arteriole diameters were quantified prior to HTK-perfusion and/or ischemia, and at 0, 1, and 2 h after restoration of blood flow. In all groups, the number of rolling leukocytes increased with time, whereas I/R induced a slight increase in leukocyte adhesion. After ischemia, capillary perfusion rapidly recovered to about 50% and returned to near normal (90%) after 2 h. HTK at 22°C did not affect the assessed microcirculation variables, whereas HTK at 4°C reduced leukocyte rolling, but not adhesion. Therefore, microvascular function of HTK-perfused muscles was not better preserved during warm I/R than that of nonperfused muscles. Contrary to other preservation solutions, HTK perfusion in itself was not detrimental to the microcirculation. © 2005 Wiley-Liss, Inc. Microsurgery 25:174,180, 2005. [source] Linearity and reliability of the mechanomyographic amplitude versus dynamic torque relationships for the superficial quadriceps femoris musclesMUSCLE AND NERVE, Issue 3 2010Matthew S. Stock MS Abstract The purpose of this investigation was to examine the linearity and reliability of the mechanomyographic (MMG) amplitude versus dynamic torque relationships for the vastus lateralis (VL), rectus femoris (RF), and vastus medialis (VM) muscles. Nine healthy men and 11 healthy women performed submaximal to maximal, concentric, isokinetic muscle actions of the leg extensors at 30° s,1 on two occasions. Surface MMG signals were detected from the VL, RF, and VM of the dominant thigh during both trials. The ranges of the coefficients of determination for the MMG amplitude versus dynamic torque relationships were 0.01,0.94 for the VL, 0.01,0.84 for the RF, and 0.19,0.96 for the VM. The intraclass correlation coefficients for the linear MMG amplitude versus torque slope coefficients were 0.823 (VL), 0.792 (RF), and 0.927 (VM). These results indicate that, when analyzed for individual subjects, the MMG amplitude versus dynamic torque relationships demonstrated inconsistent linearity. When using MMG in the clinical setting, dynamic muscle actions of the superficial quadriceps femoris muscles do not appear to be appropriate for assessing changes in muscle function during strength training. Muscle Nerve, 2009 [source] Impact of varying pulse frequency and duration on muscle torque production and fatigue,MUSCLE AND NERVE, Issue 4 2007Chris M. Gregory PhD Abstract Neuromuscular electrical stimulation (NMES) involves the use of electrical current to facilitate contraction of skeletal muscle. However, little is known concerning the effects of varying stimulation parameters on muscle function in humans. The purpose of this study was to determine the extent to which varying pulse duration and frequency altered torque production and fatigability of human skeletal muscle in vivo. Ten subjects underwent NMES-elicited contractions of varying pulse frequencies and durations as well as fatigue tests using stimulation trains of equal total charge, yet differing parametric settings at a constant voltage. Total charge was a strong predictor of torque production, and pulse trains with equal total charge elicited identical torque output. Despite similar torque output, higher- frequency trains caused greater fatigue. These data demonstrate the ability to predictably control torque output by simultaneously controlling pulse frequency and duration and suggest the need to minimize stimulation frequency to control fatigue. Muscle Nerve, 2007 [source] Sarcoplasmic reticulum: The dynamic calcium governor of muscleMUSCLE AND NERVE, Issue 6 2006Ann E. Rossi MS Abstract The sarcoplasmic reticulum (SR) provides feedback control required to balance the processes of calcium storage, release, and reuptake in skeletal muscle. This balance is achieved through the concerted action of three major classes of SR calcium-regulatory proteins: (1) luminal calcium-binding proteins (calsequestrin, histidine-rich calcium-binding protein, junctate, and sarcalumenin) for calcium storage; (2) SR calcium release channels (type 1 ryanodine receptor or RyR1 and IP3 receptors) for calcium release; and (3) sarco(endo)plasmic reticulum Ca2+ -ATPase (SERCA) pumps for calcium reuptake. Proper calcium storage, release, and reuptake are essential for normal skeletal muscle function. We review SR structure and function during normal skeletal muscle activity, the proteins that orchestrate calcium storage, release, and reuptake, and how phenotypically distinct muscle diseases (e.g., malignant hyperthermia, central core disease, and Brody disease) can result from subtle alterations in the activity of several key components of the SR calcium-regulatory machinery. Muscle Nerve, 2006 [source] Clinical evaluation of pelvic floor muscle function in continent and incontinent womenNEUROUROLOGY AND URODYNAMICS, Issue 3 2004Annemie Devreese Abstract Aims The aim of the study was to investigate the reliability of a scoring system for the investigation of voluntary and reflex co-contractions of abdominal and pelvic floor muscles in lying, sitting, and standing positions in continent and incontinent women. Methods A visual inspection and digital (strength, tone, speed, and endurance) palpation scale was developed to measure the coordination of the lower abdominal and pelvic floor muscles. Inter-observer reliability of the scales was investigated in 40 continent and 40 incontinent women. Differences between the continent and incontinent group were analysed. Results Inter-observer reliability for the visual inspection scale showed kappa values between 0.91 and 1.00, for tone percentage of agreement ranged from 95 to 100% (superficial) and 95 to 98% (deep muscle). Weighted Kappa (Kw) varied from 0.77 to 0.95 for strength and 0.75 to 0.98 for the inward movement of superficial and deep pelvic floor muscles. Kw for coordination between the superficial and deep part of the pelvic floor muscles groups was from 0.87 to 0.88 and 0.97 to 1.00 for endurance and global speed of the pelvic floor contraction. The continent women exhibited significantly better coordination between the pelvic floor and lower abdominal muscles during coughing in all three positions. Also the superficial part of the inward movement, the feeling and the coordination of the pelvic floor muscles were significantly better in the continent group. Conclusions Visual inspection and digital tests are easy and reliable methods by which insight can be gained into the multi-muscular activity and coordination of the pelvic floor and lower abdominal muscles in continent and incontinent women. Neurourol. Urodynam. 23:190,197, 2004. © 2004 Wiley-Liss, Inc. [source] The Role of Cytokines in Regulating Protein Metabolism and Muscle FunctionNUTRITION REVIEWS, Issue 2 2002Elena Zoico M.D. Multiple lines of evidence suggest that cytokines influence different physiologic functions of skeletal muscle cells, including anabolic and catabolic processes and programmed cell death. Cytokines play an important role not only in muscle homeostasis, therefore, but also in the pathogenesis of different relevant clinical conditions characterized by alterations in protein metabolism. Recently discovered cytokines, such as ciliary neurotrophic factor and growth/differentiation factor-8, as well as the more studied tumor necrosis factor-,, interleukin-1, interleukin-6, and the interferons, have been implicated in the regulation of muscle protein turnover. Their postreceptor signaling pathways, proteolytic systems, and the mechanisms of protein synthesis inhibition involved in different catabolic conditions have been partially clarified. Moreover, recent studies have shown that cytokines can directly influence skeletal muscle contractility independent of changes in muscle protein content. Even though several gaps remain in our understanding, these observations may be useful in the development of strategies to control protein metabolism and muscle function in different clinical conditions. [source] | ||||||||||||||||||||||||||||||||||