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Gastrocnemius Muscle (gastrocnemius + muscle)
Kinds of Gastrocnemius Muscle Selected AbstractsInvestigation of the Relationship Between Stimulus Parameters and a Human Muscle Contraction Force During Stimulation of the Gastrocnemius MuscleARTIFICIAL ORGANS, Issue 2 2010Piotr Kaczmarek Abstract The article presents the results of investigations on the influence of biphasic stimulus parameters such as duration and stimulus interphase interval (IPI) on a gastrocnemius muscle contraction force. Seven healthy volunteers participated in this experiment, and 24 different stimuli patterns were tested. Special attention was paid to the comfort level of a sensory perception while the electrostimulation was applied. During the test, an optimal stimulus pattern evoking contraction at the level over 15% maximum voluntary contraction force and preserving a good comfort perception reported by all of the participants was investigated. It was found that bursts of pulses with width 175 µs and the IPI from 50 to 1000 µs satisfied these criteria. Moreover, it was observed that the increase of the IPI duration generated a significantly stronger contraction force in comparison with the stimulation with the standard biphasic pulses (IPI = 0 µs) having the same amplitude, frequency, and pulse duration. This shows that the modulation of the IPI might be a potentially useful support for the standard force-control methods and may find an application in neuromuscular electrical stimulation systems. [source] Force,frequency and force,length properties in skeletal muscle following unilateral focal ischaemic insult in a rat modelACTA PHYSIOLOGICA, Issue 3 2009G. N. Dormer Abstract Aim:, Our purpose was to quantify skeletal muscle properties following unilateral focal ischaemic insult (stroke) in a rat model. Methods:, Male rats were divided into two groups: stroke and 2 weeks recovery (n = 8) and control group (n = 7). Stroke was induced in the area of the motor neocortex containing hind limb corticospinal neurones. Contractile properties of the medial gastrocnemius muscle were measured in situ in both limbs. Force,length and force,frequency properties were measured before and 35 min after 5 min fatiguing stimulation. Results:, Stroke resulted in bilateral tetanic fade during 200 Hz stimulation. When normalized to 100 Hz contractions, force at 200 Hz was 95.4 ± 0.9% for the paretic muscles, 96.7 ± 1.7% for non-paretic muscles and 102.2 ± 1.0% for muscles of control rats (P = 0.006). Prior to fatiguing contractions, there was no difference in the length dependence of force. During repetitive contractions, active force fell significantly to 19 ± 4 and 25 ± 5% of initial force in paretic and non-paretic muscles of animals with a stroke respectively. In control animals active force fell to 37 ± 5%. During repetitive contractions, fusion index increased in muscles of stroke animals to 1.0 ± 0 but in control animals it was 0.95 ± 0.02. There was selective force depression at short lengths for fatigued paretic muscle (significant difference at muscle lengths less than reference length ,2 mm). Conclusion:, The tetanic fade at high stimulation frequencies indicates that there may be activation failure following focal ischaemic insult. The greater magnitude of fatigue and selective depression at short lengths following repetitive contractions should be investigated further. [source] Changes in the contractile properties of motor units in the rat medial gastrocnemius muscle after one month of treadmill trainingACTA PHYSIOLOGICA, Issue 4 2008M. Pogrzebna Abstract Aim:, The influence of 4 weeks treadmill training on the contractile properties of motor units (MUs) in the rat medial gastrocnemius muscle was investigated. Methods:, A population of 18 Wistar rats was divided into two groups: trained on a treadmill (n = 7, locomotion speed 27 cm s,1, 1 km daily, 5 days a week, for 4 weeks) and control (n = 11). The contractile properties of isolated MUs were studied. Functional isolation of units was achieved by electrical stimulation of filaments of the ventral roots. A total of 299 MUs were investigated (142 in the control group and 157 in the trained group). They were divided into fast fatigable (FF), fast resistant to fatigue (FR) and slow (S). Their proportions and parameters of contractions were analysed. Results:, Following training, the number of FF units decreased and the number of FR units increased. The distribution of the fatigue index changed within these two types of fast units. The twitch and tetanus forces increased considerably in fast MUs, mainly in those of the FF type. The contraction and relaxation times shortened in the FR and S MUs. The steep part of the force,frequency curves shifted towards higher stimulation frequencies in FR and S units, while in FF units the shift was in the opposite direction. Conclusion:, The significant change in the proportions of fast MUs following training indicates FF to FR transformation. The various effects of training seen in the different MU types help explain the rationale behind mixed training. [source] Metabolic cost of lengthening, isometric and shortening contractions in maximally stimulated rat skeletal muscleACTA PHYSIOLOGICA, Issue 2 2004J. G. M. Beltman Abstract Aim:, The present study investigated the energy cost of lengthening, isometric and shortening contractions in rat muscle (n = 19). Methods:, With electrical stimulation the rat medial gastrocnemius muscle was maximally stimulated to perform 10 lengthening, isometric and shortening contractions (velocity 25 mm s,1) under experimental conditions (e.g. temperature, movement velocity) that resemble conditions in human movement. Results:, Mean ± SD force,time-integral of the first contraction was significantly different between the three protocols, 2.4 ± 0.2, 1.7 ± 0.2 and 1.0 ± 0.2 N s, respectively (P < 0.05). High-energy phosphate consumption was not significantly different between the three modes of exercise but a trend could be observed from lengthening (7.7 ± 2.7 ,mol , P muscle,1) to isometric (8.9 ± 2.2 ,mol , P muscle,1) to shortening contractions (10.4 ± 1.6 ,mol , P muscle,1). The ratio of high-energy phosphate consumption to force,time-integral was significantly lower for lengthening [0.3 ± 0.1 ,mol , P (N s),1] and isometric [0.6 ± 0.2 ,mol , P (N s),1] contractions compared with shortening [1.2 ± 0.2 ,mol , P (N s),1] contractions (P < 0.05). Conclusion:, The present results of maximally stimulated muscles are comparable with data in the literature for voluntary human exercise showing that the energy cost of force production during lengthening exercise is ,30% of that in shortening exercise. The present study suggests that this finding in humans probably does reflect intrinsic muscle properties rather than effects of differential recruitment and/or coactivation. [source] Effects of transient muscle contractions and stretching on the tendon structures in vivoACTA PHYSIOLOGICA, Issue 2 2002K. KUBO ABSTRACT This study compared the effects of static stretching (ST) and repeated muscle contractions (CON) on the viscoelastic properties of tendon structures in vivo. Eight male subjects performed ST (passively flexed to 35 of dorsiflexion) for 5 min and 50 repetitions of isometric maximum voluntary contraction (MVC) for 3 s each with 3 s relaxation. Before and after each task, the elongation of the tendon and aponeurosis of the medial gastrocnemius muscle (MG) was directly measured by ultrasonography, while the subjects performed ramp isometric plantar flexion up to MVC, followed by a ramp relaxation. The relationship between the estimated muscle force (Fm) and tendon elongation (L) during the ascending phase was applied to a linear regression, the slope of which was defined as stiffness of the tendon structures. The percentage of the area within the Fm,L loop to the area beneath the curve during the ascending phase was calculated as an index representing hysteresis. The ST protocol significantly decreased the stiffness (,8%) and hysteresis (29%)., respectively. In contrast, the CON protocol significantly decreased the stiffness, but not the hysteresis. These results suggested that the stretching and repeated contractions would make the tendon structures more complaint, and further decreased the hysteresis of the tendon structures. [source] Long-term effects of botulinum toxin A in children with cerebral palsyDEVELOPMENTAL MEDICINE & CHILD NEUROLOGY, Issue 2 2009KRISTINA TEDROFF MD The long-term effects of botulinum toxin A (BoNT-A) treatment in children with cerebral palsy (CP) are still elusive. We studied a prospective clinical cohort of 94 children with different subtypes (50% spastic diplegic CP, 22% hemiplegic CP, 25% tetraplegic CP, 3% dyskinetic CP), sex (55% male, 45% female), severity according to Gross Motor Function Classification System (29% Level I, 15% Level II, 16% Level III, 17% Level IV, 23% Level V), and age (median 5y 4mo, range 11mo,17y 8mo). The longest follow-up time was 3 years 7 months (median 1y 6mo) and included a maximum of eight injections per muscle (median two injections to a specific muscle). Outcome measurements were muscle tone (Modified Ashworth Scale) and joint range of motion (ROM). Assessments were made at a minimum before and 3 months after each injection. Ninety-five per cent confidence intervals for differences from baseline were used to identify significant changes. BoNT-A injections induced reduction of long-term spasticity in all muscle-groups examined: the gastrocnemius, hamstring, and adductor muscles. The reduction in tone was most distinct in the gastrocnemius muscle, and each repeated injection produced an immediate reduction in muscle tone. However, improvement in ROM was brief and measured only after the first injections, whereupon the ROM declined. Thus, the results suggest that BoNT-A can be effective in reducing muscle tone over a longer period, but not in preventing development of contractures in spastic muscles. The dissociation between the effects on muscle tone and ROM indicates that development of contractures is not coupled to increased muscle tone only, but might be caused by other mechanisms. [source] Intramuscular AAV delivery of NT-3 alters synaptic transmission to motoneurons in adult ratsEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 6 2010Jeffrey C. Petruska Abstract We examined whether elevating levels of neurotrophin-3 (NT-3) in the spinal cord and dorsal root ganglion (DRG) would alter connections made by muscle spindle afferent fibers on motoneurons. Adeno-associated virus (AAV) serotypes AAV1, AAV2 and AAV5, selected for their tropism profile, were engineered with the NT-3 gene and administered to the medial gastrocnemius muscle in adult rats. ELISA studies in muscle, DRG and spinal cord revealed that NT-3 concentration in all tissues peaked about 3 months after a single viral injection; after 6 months NT-3 concentration returned to normal values. Intracellular recording in triceps surae motoneurons revealed complex electrophysiological changes. Moderate elevation in cord NT-3 resulted in diminished segmental excitatory postsynaptic potential (EPSP) amplitude, perhaps as a result of the observed decrease in motoneuron input resistance. With further elevation in NT-3 expression, the decline in EPSP amplitude was reversed, indicating that NT-3 at higher concentration could increase EPSP amplitude. No correlation was observed between EPSP amplitude and NT-3 concentration in the DRG. Treatment with control viruses could elevate NT-3 levels minimally resulting in measurable electrophysiological effects, perhaps as a result of inflammation associated with injection. EPSPs elicited by stimulation of the ventrolateral funiculus underwent a consistent decline in amplitude independent of NT-3 level. These novel correlations between modified NT-3 expression and single-cell electrophysiological parameters indicate that intramuscular administration of AAV(NT-3) can exert long-lasting effects on synaptic transmission to motoneurons. This approach to neurotrophin delivery could be useful in modifying spinal function after injury. [source] Expression of cell fate determinants and plastic changes after neurotoxic lesion of adult mice spinal cord by cholera toxin-B saporinEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 8 2010Rosario Gulino Abstract Recent studies have attempted to repair the damaged spinal cord (SC) by stimulating neurogenesis or neuroplasticity. Sonic hedgehog (Shh), Notch-1 and Numb are involved in the stem cell functioning. Additionally, Notch-1 has a role as modulator of synaptic plasticity. However, little is known about the role of these proteins in the adult SC after removal of motoneurons. In this study, we have injected cholera toxin-B saporin into the gastrocnemius muscle to induce a depletion of motoneurons within the lumbar SC of adult mice, and analysed the expression of choline acetyltransferase (ChAT), Synapsin-I, Shh, Notch-1 and Numb proteins. The functional outcome of the lesion was monitored by grid walk and rotarod tasks. The neurotoxin lesion determined a motoneuron depletion and a transient decrease of ChAT, Synapsin-I, Shh and Numb levels in the lumbar SC. ChAT was associated with Synapsin-I expression and motor performance at 1 week but not 1 month after lesion, suggesting that the recovery of locomotion could depend on synaptic plasticity, at least in an early phase. Shh and Notch-1 were associated with Synapsin-I levels, suggesting a role in modulating synaptic plasticity. Numb expression also appeared reduced after lesion and linked to motor performance. Moreover, unlike other lesion models, we observed glial reaction but no evidence of cell proliferation within the depleted SC. Given the mentioned roles of Shh, Notch-1 and Numb, we believe that an in vivo manipulation of their signalling after lesion could represent a suitable way to improve functional recovery by modulating synaptic plasticity and/or neurogenesis. [source] Changes in contractile properties of motor units of the rat medial gastrocnemius muscle after spinal cord transectionEXPERIMENTAL PHYSIOLOGY, Issue 5 2006Jan Celichowski The effects of complete transection of the spinal cord at the level of Th9/10 on contractile properties of the motor units (MUs) in the rat medial gastrocnemius (MG) muscle were investigated. Our results indicate that 1 month after injury the contraction time (time-to-peak) and half-relaxation time were prolonged and the maximal tetanic force in most of the MUs in the MG muscle of spinal rats was reduced. The resistance to fatigue also decreased in most of the MUs in the MG of spinal animals. Moreover, the post-tetanic potentiation of twitches in MUs diminished after spinal cord transection. Criteria for the division of MUs into three types, namely slow (S), fast fatigue resistant (FR) and fast fatigable (FF), applied in intact animals, could not be directly used in spinal animals owing to changes in contractile properties of MUs. The ,sag' phenomenon observed in unfused tetani of fast units in intact animals essentially disappeared in spinal rats and it was only detected in few units, at low frequencies of stimulation only. Therefore, the MUs in spinal rats were classified as fast or slow on the basis of an adjusted borderline of 20 ms, instead of 18 ms as in intact animals, owing to a slightly longer contraction time of those fast motor units with the ,sag'. We conclude that all basic contractile properties of rat motor units in the medial gastrocnemius muscle are significantly changed 1 month after complete spinal cord transection, with the majority of motor units being more fatigable and slower than those of intact rats. [source] Capillary supply and gene expression of angiogenesis-related factors in murine skeletal muscle following denervationEXPERIMENTAL PHYSIOLOGY, Issue 3 2005A. Wagatsuma Capillary supply of skeletal muscle decreases during denervation. To gain insight into the regulation of this process, we investigated capillary supply and gene expression of angiogenesis-related factors in mouse gastrocnemius muscle following denervation for 4 months. Frozen transverse sections were stained for alkaline phosphatase to detect endogenous enzyme in the capillary endothelium. The mRNA for angiogenesis-related factors, including hypoxia inducible factor-1, (HIF-1,), vascular endothelial growth factor (VEGF), kinase insert domain-containing receptor/fetal liver kinase-1 (KDR/Flk-1), fms-like tyrosine kinase (Flt-1), angiopoietin-1 and tyrosine kinase with Ig and epidermal growth factor(EGF) homology domain 2 (Tie-2), was analysed using a semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR). The fibre cross-sectional area after denervation was about 20% of the control value, and the capillary to fibre ratio was significantly lower in denervated than in control muscles. The number of capillaries around each fibre also decreased to about 40% of the control value. These observations suggest that muscle capillarity decreases in response to chronic denervation. RT-PCR analysis showed that the expression of VEGF mRNA was lower in denervated than in control muscles, while the expression of HIF-1, mRNA remained unchanged. The expression levels of the KDR/Flk-1 and Flt-1 genes were decreased in the denervated muscle. The expression levels of angiopoietin-1 but not Tie-2 genes were decreased in the denervated muscle. These findings indicate that reduction in the expression of mRNAs in the VEGF/KDR/Flk-1 and Flt-1 as well as angiopoietin-1/Tie-2 signal pathways might be one of the reasons for the capillary regression during chronic denervation. [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] Cover Picture: J. Biophoton.JOURNAL OF BIOPHOTONICS, Issue 6 20086/200 Mouse muscle fibres (gastrocnemius muscle) 3D reconstruction. Infrared excitation at 800 nm. Nuclei are labelled with Hoechst33342 (red) and acquired in the epi-channel in the spectral range 440,480 nm. SHG (green) from myosin fibres is acquired in transmission channel. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Significant differences in proton trimethyl ammonium signals between human gastrocnemius and soleus muscleJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 5 2004Jiani Hu PhD Abstract Purpose To study the apparent heterogeneous characteristics of trimethyl ammonium (TMA) in healthy human muscles at rest, and to illustrate the importance of establishing the baseline characteristics of proton metabolites in muscles with a West Nile patient. Materials and Methods Point-resolved spectroscopy (PRESS) magnetic resonance spectroscopy imaging (MRSI) with lipid suppression and optional outer-volume presaturation were used to acquire 1H spectra of human muscles at rest at 1.5 Tesla. A total of 28 subjects (27 normal volunteers and 1 patient with West Nile disease) between the ages of 22 and 76 participated in the study. Results The apparent T2 values of TMA for soleus and gastrocnemius muscles in normal volunteers are 180 ± 50 and 80 ± 20 msec, respectively. This difference has profound effects on the apparent spectral pattern of 1H metabolites. The TMA/total creatine (tCr) spectral pattern of the soleus muscle of a West Nile patient resembles that of gastrocnemius muscle of healthy volunteers. Conclusion There are significant differences in the apparent T2 values of TMA between healthy soleus and gastrocnemius muscles at rest. It is important to establish the baseline characteristics of proton metabolites before clinical or physiological studies can be performed. J. Magn. Reson. Imaging 2004;19:617,622. © 2004 Wiley-Liss, Inc. [source] Popliteal artery entrapment syndrome: Non-invasive diagnosis by MDCT and MRIJOURNAL OF MEDICAL IMAGING AND RADIATION ONCOLOGY, Issue 2007D Utsunomiya SUMMARY We present a case of a 19-year-old male patient complaining of right leg pain, which appeared after exercise and abated with rest. Computed tomography (CT) and magnetic resonance angiography (MRA) showed occlusion of right popliteal artery. Volume rendering CT image showed not only occlusion of right popliteal artery but also abnormal course of the medial head of the gastrocnemius muscle (MHG). CT and MR images of right popliteal fossa showed the abnormal anatomy that MHG coursed between popliteal artery with thrombus and popliteal vein. Popliteal artery entrapment syndrome was diagnosed non-invasively by multidetector CT and MRI. Sectional radiological and three-dimensional images are useful for not only depiction of the arterial changes but also identification of the abnormal anatomic structures responsible for the entrapment. [source] Loss of synaptophysin-positive boutons on lumbar motor neurons innervating the medial gastrocnemius muscle of the SOD1G93A G1H transgenic mouse model of ALSJOURNAL OF NEUROSCIENCE RESEARCH, Issue 5 2005Da Wei Zang Abstract Amyotrophic lateral sclerosis (ALS) is a common form of motor neuron disease (MND) that involves both upper and lower nervous systems. In the SOD1G93A G1H transgenic mouse, a widely used animal model of human ALS, a significant pathology is linked to the degeneration of lower motor neurons in the lumbar spinal cord and brainstem. In the current study, the number of presynaptic boutons immunoreactive for synaptophysin was estimated on retrogradely labeled soma and proximal dendrites of , and , motor neurons innervating the medial gastrocnemius muscle. No changes were detected on both soma and proximal dendrites at postnatal day 60 (P60) of , and , motor neurons. By P90 and P120, however, , motor neuron soma had a reduction of 14 and 33% and a dendritic reduction of 19 and 36%, respectively. By P90 and P120, , motor neuron soma had a reduction of 17 and 41% and a dendritic reduction of 19 and 35%, respectively. This study shows that levels of afferent innervation significantly decreased on surviving , and , motor neurons that innervate the medial gastrocnemius muscle. This finding suggests that the loss of motor neurons and the decrease of synaptophysin in the remaining motor neurons could lead to functional motor deficits, which may contribute significantly to the progression of ALS/MND. © 2005 Wiley-Liss, Inc. [source] Cell traffic between donor and recipient following rat limb allograftJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 1 2005Keiichi Muramatsu Abstract Although cell traffic from the graft into the recipient and from the recipient into the graft had been noticed in allogeneic organ transplantation, little is known following whole-limb allografting. This study was conducted to define cell migration between donor and recipient. Sixty-seven vascularized hind limb allotransplantations were performed in rat sex-mismatched pairs and the recipient animals were treated with FK506 immunosuppression. The ratio of donor and recipient cells was evaluated by semi-quantitative PCR using the specific primers of the Y-chromosome. Allografted limbs had no rejection episode until the final assessment. The male recipient cells were detected in female limb grafts not at 1 week but at 48 weeks after transplantation. The male donor cells were detected in the humerus and tibia in the female recipient but not in the gastrocnemius muscle and leg skin. Our results demonstrated that recipient-derived cells gradually migrated into the grafted bone, muscle and skin cells with the duration of time. Donor-derived cells migrated into the healthy bones but not into the healthy muscle and skin. Because active regeneration occurs in the grafted limb to compensate graft damage secondary to ischemia and operative intervention, recipient-derived cells may mediate a muscular and dermo-epidermal renewal. © 2004 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved. [source] Ethanol Feeding Impairs Insulin-Stimulated Glucose Uptake in Isolated Rat Skeletal Muscle: Role of Gs , and cAMPALCOHOLISM, Issue 8 2005Qiang Wan Background: The mechanism by which chronic alcohol consumption impairs insulin sensitivity is unclear. We investigated the role of the Gs ,,mediated pathway in decreasing insulin sensitivity in skeletal muscle after ethanol consumption. Methods: Sixty male Wistar rats, divided into four groups, received either distilled water (controls; group I) or ethanol, which was administered by a gastric tube as a single daily dose of 5 g/kg (group II), 2.5 g/kg (group III), or 0.5 g/kg (group IV). After 20 weeks, fasting plasma glucose and serum insulin levels were measured. The hyperinsulinemic-euglycemic clamp study was performed under anesthesia to estimate whole-body insulin sensitivity. Insulin-stimulated glucose uptake was measured in vitro in dissected gastrocnemius muscle. Expression of glut4, Gs ,, and Gi , was quantified using real-time PCR analysis and western blotting. cAMP levels were measured by ELISA. Results: Compared with controls, the following observations were made: (1) the hyperinsulinemic-euglycemic clamp study revealed impaired insulin action at the whole-body level after ethanol treatment; (2) chronic ethanol feeding at 5 g/kg and 2.5 g/kg significantly decreased both basal and insulin-stimulated glucose uptakes in isolated skeletal muscle (p < 0.05), which was accompanied by decreased expression of glut4 (p < 0.05); (3) Gs , (mRNA and protein) expression in skeletal muscle was significantly increased in all three ethanol groups (p < 0.05), and cAMP levels were also increased by ethanol treatment (p < 0.05); and (4) there was no significant change in Gi , expression in all three ethanol groups. Conclusions: Chronic ethanol exposure decreased insulin-induced glucose uptake in rat skeletal muscle, which was associated with increased expression of Gs ,. Because Gs , is a negative regulator of insulin sensitivity, the alteration in Gs , expression may contribute to the ethanol-induced impairment of insulin signal transduction. [source] Radiographic features of a lateral extracapsular wire suture in the canine cranial cruciate deficient stifleJOURNAL OF SMALL ANIMAL PRACTICE, Issue 10 2001C. K. Stork Radiographs of 74 dogs (84 stifles) presented with a cranial cruciate ligament rupture and surgically treated using a lateral extracapsular wire (LEW) were reviewed. A strand of orthopaedic wire was surgically placed caudally around the lateral fabella and through a predrilled hole in the tibial crest. At six week follow-up, the LEW was broken at least once in 26 of 33 stifles, predominantly in the area of the lateral fabella. In five stifles, the LEW had slipped off the fabella and was displaced distally along the gastrocnemius muscle. Six months after surgery, the LEW was often broken at several sites. LEW migration was rare. Osteolysis and sclerosis at the site of LEW penetration through the tibial crest occurred in about two-thirds of the stifles examined. [source] Time-dependent expression of myostatin RNA transcript and protein in gastrocnemius muscle of mice after sciatic nerve resectionMICROSURGERY, Issue 5 2007Chenxin Shao M.D. Myostatin, a member of the transforming growth factor-, (TGF-,) superfamily, has been identified as a negative regulator of skeletal muscle mass. To provide more data on the role of myostatin in denervation-induced muscle atrophy, we examined the time-dependent changes in myostatin mRNA and protein as well as Smad2 and phospho-Smad2 protein levels in the denervated gastrocnemius muscle of mice after sciatic neurectomy, using quantitative real-time RT-PCR and Western blotting, respectively. We conducted morphometric analyses to measure the wet weight ratio of the denervated muscle (the operated side/contralateral nonoperated side) and the cross-sectional area of muscle fibers, and observed the morphology of denervated muscle. The experimental results showed that in the early stage of denervation, the levels of myostatin mRNA and protein in the denervated gastrocnemius muscle increased instantly, reaching a peak at day 3 and day 7 after sciatic neurectomy, respectively, when compared with the normal values. In addition, the phospho-Smad2 protein was observed to have a similar expression profile to that of the myostatin mRNA. The present study perhaps opens a new window into myostatin modulation in muscle atrophy due to denervation. © 2007 Wiley-Liss, Inc. Microsurgery, 2007. [source] Muscle biopsy substantiates long-term MRI alterations one year after a single dose of botulinum toxin injected into the lateral gastrocnemius muscle of healthy volunteers,MOVEMENT DISORDERS, Issue 10 2009A. Sebastian Schroeder MD Abstract Despite numerous clinical and experimental studies on botulinum toxin type A (BoNT/A), long-term alterations of muscle texture and fine structure following BoNT/A treatment have thus far not been studied in normal human skeletal muscle. After obtaining institutional review board approval, we performed a prospective, placebo-controlled, double-blinded follow-up study on two healthy adults using magnetic resonance imaging (MRI) and muscle biopsy to visualize long-term alterations after a single BoNT/A injection into the lateral head of the gastrocnemius muscle. MRI disclosed a high-signal-intensity pattern in short tau inversion recovery sequences, and a reduction of the cross-sectional area in the BoNT/A-injected, but not in the saline-injected contralateral control muscle (at 6 to 9 months in volunteer A: 73%, in B: 62%; at 12 months in A: 88%, and in B: 78%). Enzyme histochemistry, 12 months after injection, confirmed neurogenic atrophy of muscle fibers only in the BoNT/A-injected muscle. Electron microscopy revealed additional degenerative changes at the neuromuscular junction. The data confirm that MRI is a suitable tool to monitor the long-term effect of BoNT/A on skeletal muscle. Neurogenic muscle atrophy following a single BoNT/A injection should be taken into consideration when repeated BoNT/A injections into the same muscles are proposed. © 2009 Movement Disorder Society [source] Molecular targets of botulinum toxin at the mammalian neuromuscular junctionMOVEMENT DISORDERS, Issue S8 2004Dorothy D. Whelchel MS Abstract The molecular targets of botulinum neurotoxins (BoNTs) are SNARE (soluble N -ethylmaleimide-sensitive factor- attachment protein- receptor) proteins necessary for neurotransmitter release. BoNT are powerful therapeutic agents in the treatment of numerous neurological disorders. The goals of this study were to (1) assess toxin diffusion by measuring substrate cleavage in adjacent and distant muscles, and (2) characterize the clinical course using SNARE protein chemistry. A small volume of BoNT/A was injected unilaterally into the mouse gastrocnemius muscle. Motor impairment was limited to the toxin-treated limb. No systemic illness or deaths occurred. At five time points, a subset of mice were killed, and muscles from both hindlimbs, and the diaphragm, were collected. Protein samples were examined for changes in SNAP-25 (synaptosomal-associated protein of Mr = 25 kDa) using immunochemistry. SNAP-25 cleavage product was noted in the toxin-treated limb as early as 1 day postinjection and continued through day 28. Onset and peak levels of substrate cleavage corresponded to the onset and peak clinical response. Cleavage was observed in adjacent and distant muscles, demonstrating that substrate cleavage is a sensitive indicator of toxin diffusion. Significant increases in full-length SNAP-25 and vesicle-associated membrane protein II were evident early in the impaired limb and continued through day 28. The increased SNARE protein most likely originates from nerve terminal sprouts. © 2004 Movement Disorder Society [source] Effects of stimulation frequency and pulse duration on fatigue and metabolic cost during a single bout of neuromuscular electrical stimulationMUSCLE AND NERVE, Issue 5 2010Julien Gondin PhD Abstract We have investigated the effects of stimulation frequency and pulse duration on fatigue and energy metabolism in rat gastrocnemius muscle during a single bout of neuromuscular electrical stimulation (NMES). Electrical pulses were delivered at 100 Hz (1-ms pulse duration) and 20 Hz (5-ms pulse duration) for the high (HF) and low (LF) frequency protocols, respectively. As a standardization procedure, the averaged stimulation intensity, the averaged total charge, the initial peak torque, the duty cycle, the contraction duration and the torque-time integral were similar in both protocols. Fatigue was assessed using two testing trains delivered at a frequency of 100 Hz and 20 Hz before and after each protocol. Metabolic changes were investigated in vivo using 31P-magnetic resonance spectroscopy (31P-MRS) and in vitro in freeze-clamped muscles. Both LF and HF NMES protocols induced the same decrease in testing trains and metabolic changes. We conclude that, under carefully controlled and comparable conditions, the use of low stimulation frequency and long pulse duration do not minimize the occurrence of muscle fatigue or affect the corresponding stimulation-induced metabolic changes so that this combination of stimulation parameters would not be adequate in the context of rehabilitation. Muscle Nerve, 2010 [source] Alterations in inorganic phosphate in mouse hindlimb muscles during limb disuse,NMR IN BIOMEDICINE, Issue 2 2008Neeti Pathare Abstract Muscle disuse induces a wide array of structural, biochemical, and neural adaptations in skeletal muscle, which can affect its function. We recently demonstrated in patients with an orthopedic injury that cast immobilization alters the resting Pi content of skeletal muscle, which may contribute to loss of specific force. The goal of this study was to determine the direct effect of disuse on the basal phosphate content in skeletal muscle in an animal model, avoiding the confounding effects of injury/surgery. 31P and 1H MRS data were acquired from the gastrocnemius muscle of young adult mice (C57BL6 female, n,=,8), at rest and during a reversible ischemia experiment, before and after 2 weeks of cast immobilization. Cast immobilization resulted in an increase in resting Pi content (75%; p,<,0.001) and the Pi to phosphocreatine (PCr) ratio (Pi/PCr; 80%, p,<,0.001). The resting concentrations of ATP, PCr and total creatine (PCr,+,creatine) and the intracellular pH were not significantly different after immobilization. During ischemia (30,min), PCr concentrations decreased to 54,±,2% and 52,±,6% of the resting values in pre-immobilized and immobilized muscles, respectively, but there were no detectable differences in the rates of Pi increase or PCr depletion (0.55,±,0.01,mM min,1 and 0.52,±,0.03,mM min,1 before and after immobilization, respectively; p,=,0.78). At the end of ischemia, immobilized muscles had a twofold higher phosphorylation potential ([ADP][Pi]/[ATP]) and intracellular buffering capacity (3.38,±,0.54 slykes vs 6.18,±,0.57 slykes). However, the rate of PCr resynthesis (kPCr) after ischemia, a measure of in vivo mitochondrial function, was significantly lower in the immobilized muscles (0.31,±,0.04,min,1) than in pre-immobilized muscles (0.43,±,0.04,min,1). In conclusion, our findings indicate that 2 weeks of cast immobilization, independent of injury-related alterations, leads to a significant increase in the resting Pi content of mouse skeletal muscle. The increase in Pi with muscle disuse has a significant effect on the cytosolic phosphorylation potential during transient ischemia and increases the intracellular buffering capacity of skeletal muscle. Copyright © 2007 John Wiley & Sons, Ltd. [source] Not All Injury-induced Muscle Proteolysis Is Due to Increased Activity of the Ubiquitin/Proteasome System: Evidence for Up-Regulation of Macrophage-associated Lysosomal Proteolysis in a Model of Local TraumaNUTRITION REVIEWS, Issue 1 2003Article first published online: 16 SEP 200 A characteristic response to injury is a dramatic loss of skeletal muscle protein owing to increased muscle protein breakdown. Over the past decade, numerous studies have indicated that up-regulaton of the ubiquitin-proteasome system is a common mechanism underlying such injury-induced muscle proteolysis. However, a recent study using a single-impact trauma to the gastrocnemius muscle found that, although the rate of muscle proteolysis was dramatically increased, the ubiquitin-proteasome system was not involved. Rather, an increase in lysosomal activity, through infiltration of the damaged tissue by mononuclear macrophages, is responsible for the high rates of protein breakdown. [source] Regulation and function of Ca2+,calmodulin-dependent protein kinase II of fast-twitch rat skeletal muscleTHE JOURNAL OF PHYSIOLOGY, Issue 3 2007Adam J. Rose The activation and function of Ca2+,calmodulin-dependent kinase II (CaMKII) in contracting rat skeletal muscle was examined. The increase in autonomous activity and phosphorylation at Thr287 of CaMKII of gastrocnemius muscle in response to contractions in situ was rapid and transient, peaking at 1,3 min, but reversed after 30 min of contractions. There was a positive correlation between CaMKII phosphorylation at Thr287 and autonomous CaMKII activity. In contrast to the rapid and transient increase in autonomous CaMKII activity, the phosphorylation of the putative CaMKII substrate trisk95/triadin was rapid and sustained during contractions. There were no changes in CaMKII activity and phosphorylation or trisk95 phosphorylation in the resting contralateral muscles during stimulation. When fast-twitch muscles were contracted ex vivo, CaMKII inhibition resulted in a greater magnitude of fatigue as well as blunted CaMKII and trisk95 phosphorylation, identifying trisk95 as a physiological CaMKII substrate. In summary, skeletal muscle CaMKII activation was rapid and sustained during exercise/contraction and is mediated by factors within the contracting muscle, probably through allosteric activation via Ca2+,CaM. CaMKII may signal through trisk95 to modulate Ca2+ release in fast-twitch rat skeletal muscle during exercise/contraction. [source] The Arterial Supply of the Pelvic Limb of the Adult Ostrich (Struthio camelus)ANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 4 2010S. M. El-Nahla With 25 figures Summary Blood to the pelvic limb of the ostrich is provided by the external iliac and ischiatic arteries that arise from the descending aorta. The external iliac artery (a.) gave rise to the pubic a. that supplied the obturator muscles and continued as the femoral a. The femoral a. gave off three branches: (1) cranial coxal a. to muscles above the pre-acetabular ilium; (2) cranial femoral a. to muscles cranial to the femur, the gastrocnemius muscle, hip and stifle joints and (3) medial femoral a. to muscles caudal and medial to the femur. The ischiatic a. gave rise to the caudal coxal a. that supplied muscles caudal to the femur, muscular branches to the iliotibialis lateralis muscle and to the deep femoral a. that supplied the iliofibularis muscle, cutanea femoralis caudalis and lateralis aa., and branches to the flexors of the leg and knee joint, then terminated as the sural and popliteal arteries. The sural a. supplied most of the flexors of the foot. The popliteal a. supplied the knee joint and flexors of the leg, and then terminated as the cranial and caudal tibial arteries. The caudal tibial a. supplied flexors of the foot. The cranial tibial a. provided four branches to the knee and ankle joints and to the leg. The cranial tibial a. continued into the foot as the common dorsal metatarsal a., which gave off seven different branches to the ankle and foot. With few exceptions, the arteries of the ostrich pelvic limb are similar to those of domestic fowl. [source] The Effect of Testosterone on Gastrocnemius Muscle Fibres in Growing and Adult Male and Female Rats: A Histochemical, Morphometric and Ultrastructural Study,ANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 2 2003. Üstünel Summary In this study, the effect of testosterone on gastrocnemius muscle fibres in growing and adult rats (male and female) was examined using histochemical, morphometric and ultrastructural techniques. After physiological saline (PS), olive oil (OvO) or olive oil + testosterone (OvOT) injections on 72 rats (growing and mature, 36 male and 36 female), the sample tissues of fibre types of the gastrocnemius muscle taken were examined by histochemical [alkaline adenosine triphosphatase (alk-ATPase), acid ATPase (ac-ATPase)], morphometric and ultrastructural techniques. In PS-injected control groups, the gastrocnemius muscle of both sexes contained all the fibre types studied [slow-oxidative muscle fibres (type I), fast-oxidative glycolytic muscle fibres (type IIA) and fast-glycolytic muscle fibres (type IIB)]. The type I fibres had the smallest diameter, type IIA had a medium diameter and type IIB fibres had the largest diameter. In OvO-injected groups, it was observed that the OvO had little effect on the gastrocnemius muscles of either sex, although there was significant enlargement of type IIB fibres. After the injection of OvOT, hypertrophy of muscle fibres was determined by morphometric study. The biggest increase in diameter was on type I fibres. In addition, degenerations on some mitochondria, accumulation of lipid droplets on type I and type II fibres, an increase in glycogen particles, bifurcation of myofibrils, an increase in the number and diameter of units resembling T tubules and an increase in ribosomal content were also observed in the same group by transmission electron microscope. Consequently, it was determined that testosterone can induce protein synthesis in gastrocnemius muscle fibres, and induces changes in shape and size, and also can change the appearance and the number of fibres. [source] Proteomic investigation of the effects of weight loss in the gastrocnemius muscle of wild and NZW rabbits via 2D-electrophoresis and MALDI-TOF MSANIMAL GENETICS, Issue 3 2010A. M. Almeida Summary The study of changes within the key agents regulating metabolism during genetic upgrading because of selection can contribute to an improved understanding of genomic and physiological relationships. This may lead to increased efficiencies in animal production. These changes, regarding energy and protein metabolic saving mechanisms, can be highlighted during food restriction periods. In this study, a 20% weight reduction was induced in two rabbit breeds: New Zealand white, a selected meat producer (Oryctolagus cuniculus cuniculus), and Iberian wild rabbit (Oryctolagus cuniculus algirus), with the aim of determining differential protein expression in the gastrocnemius muscle within control (ad libitum) and restricted diet experimental animal groups, using techniques of two-dimensional gel electrophoresis and peptide mass fingerprinting. Results show that l -lactate dehydrogenase, adenylate kinase, , enolase and , enolase, fructose bisphosphate aldolase A and glyceraldehyde 3-phosphate dehydrogenase, which are enzymes involved in energy metabolism, are differentially expressed in restricted diet experimental animal groups. These enzymes are available to be further tested as relevant biomarkers of weight loss and putative objects of manipulation as a selection tool towards increasing tolerance to weight loss. Similar reasoning could be applied to 2D gel electrophoresis spots corresponding to the important structural proteins tropomyosin , chain and troponin I. Finally, a spot identified as mitochondrial import stimulation factor seems of special interest as a marker of undernutrition, and it may be the object of further studies aiming to better understand its physiological role. [source] Reversal of acid-induced and inflammatory pain by the selective ASIC3 inhibitor, APETx2BRITISH JOURNAL OF PHARMACOLOGY, Issue 4 2010Jerzy Karczewski BACKGROUND AND PURPOSE Inflammatory pain is triggered by activation of pathways leading to the release of mediators such as bradykinin, prostaglandins, interleukins, ATP, growth factors and protons that sensitize peripheral nociceptors. The activation of acid-sensitive ion channels (ASICs) may have particular relevance in the development and maintenance of inflammatory pain. ASIC3 is of particular interest due to its restricted tissue distribution in the nociceptive primary afferent fibres and its high sensitivity to protons. EXPERIMENTAL APPROACH To examine the contribution of ASIC3 to the development and maintenance of muscle pain and inflammatory pain, we studied the in vivo efficacy of a selective ASIC3 inhibitor, APETx2, in rats. KEY RESULTS Administration of APETx2 into the gastrocnemius muscle prior to the administration of low pH saline prevented the development of mechanical hypersensitivity, whereas APETx2 administration following low-pH saline was ineffective in reversing hypersensitivity. The prevention of mechanical hypersensitivity produced by acid administration was observed whether APETx2 was applied via i.m. or i.t. routes. In the complete Freund's adjuvant (CFA) inflammatory pain model, local administration of APETx2 resulted in a potent and complete reversal of established mechanical hypersensitivity, whereas i.t. application of APETx2 was ineffective. CONCLUSIONS AND IMPLICATIONS ASIC3 contributed to the development of mechanical hypersensitivity in the acid-induced muscle pain model, whereas ASIC3 contributed to the maintenance of mechanical hypersensitivity in the CFA inflammatory pain model. The contribution of ASIC3 to established hypersensitivity associated with inflammation suggests that this channel may be an effective analgesic target for inflammatory pain states. [source] Spider silk fibres in artificial nerve constructs promote peripheral nerve regenerationCELL PROLIFERATION, Issue 3 2008C. Allmeling Materials and methods: We compared isogenic nerve grafts to vein grafts with spider silk fibres, either alone or supplemented with Schwann cells, or Schwann cells and matrigel. Controls, consisting of veins and matrigel, were transplanted. After 6 months, regeneration was evaluated for clinical outcome, as well as for histological and morphometrical performance. Results: Nerve regeneration was achieved with isogenic nerve grafts as well as with all constructs, but not in the control group. Effective regeneration by isogenic nerve grafts and grafts containing spider silk was corroborated by diminished degeneration of the gastrocnemius muscle and by good histological evaluation results. Nerves stained for S-100 and neurofilament indicated existence of Schwann cells and axonal re-growth. Axons were aligned regularly and had a healthy appearance on ultrastructural examination. Interestingly, in contrast to recently published studies, we found that bridging an extensive gap by cell-free constructs based on vein and spider silk was highly effective in nerve regeneration. Conclusion: We conclude that spider silk is a viable guiding material for Schwann cell migration and proliferation as well as for axonal re-growth in a long-distance model for peripheral nerve regeneration. [source] | |||||||||||||||||||||||||