Search

We want to evaluate the feasibility of transferring a motor branch of the anterior tibial muscle (ATM) to the extensor digitorum longus (EDL) to evaluate this procedure in patients with spastic equinovarus foot (EVF) following post-stroke hemiplegia. Ten cadaveric dissections from five fresh frozen human cadavers were performed to establish the anatomic feasibility of transferring a motor branch of the deep peroneal nerve, usually destinated to the ATM, to the branch of the EDL to manage spastic EVF. Six cases (60%) presented three branches destinated to the ATM, one case (10%) presented give branches, and three cases (30%) had four branches. In all specimens, the coaptation between the motor branch to the ATM, referred as the "effector" branch, and the branch of the EDL "receiver" branch was feasible without tension and did not require any intraneural dissection. This anatomical study confirms the feasibility of transferring a motor branch from the ATM to the EDL to correct a spastic EVF. [ABSTRACT FROM AUTHOR]

Skeletal muscle is composed of fiber types that differ in mitochondrial content, antioxidant capacity, and susceptibility to apoptosis. Ceramides have been linked to oxidative stress-mediated apoptotic intracellular signalling and the enzyme neutral sphingomyelinase (nSMase) is, in part, responsible for generating these ceramides through the hydrolysis of sphingomyelin. Despite the role of ceramides in mediating apoptosis, there is a gap in the literature regarding nSMase in skeletal muscle mitochondria. This study aimed to characterize total nSMase activity and individual isoform expression in isolated subsarcolemmal (SS) mitochondria from soleus, diaphragm, plantaris, and extensor digitorum longus (EDL). Total nSMase activity did not differ between muscle types. nSMase2 content was detectable in all muscles and higher in EDL, soleus, and plantaris compared to diaphragm whereas nSMase3 was undetectable in all muscles. Finally, total nSMase activity positively correlated to nSMase2 protein content in soleus but not the other muscles. These findings suggest that nSMase associated with SS mitochondria may play a role in intracellular signalling processes involving ceramides in skeletal muscle and nSMase2 may be the key isoform, specifically in slow twitch muscle like soleus. Further studies are needed to fully elucidate the specific contribution of nSMase, along with the role of the various isoforms and mitochondrial subpopulation in generating mitochondrial ceramides in skeletal muscle, and its potential effects on mediating apoptosis. [ABSTRACT FROM AUTHOR]

Abstract Purpose The fibula flap has been established for orofacial reconstruction following ablative surgery. Donor-site morbidity of the lower leg may be explained by the harvest technique and particularly by detachment of the M. extensor halluces longus (EHL) and M. extensor digitorum longus (EDL). Material and methods On cadaveric lower leg specimens, the tendons of the EHL and EDL were dissected at the proximal phalanges and loaded with corresponding weights. The average displacement of the muscle was evaluated during the harvesting procedure. Results Cumulative detachment of the interosseous membrane caused considerable displacement of the EHL but less impairment of the EDL. Segmental and cumulative osteotomy of the fibula implicated significant displacement of both EHL and EDL. Conclusion A recommendation can be given for cautious selection of osteotomy site of the fibula and for limited sacrifice of the fibula and adjacent attachments of the extensors to keep local-site morbidity at a minimum. [ABSTRACT FROM AUTHOR]

Purpose To analyse the torque variation level that could be explained by the muscle activation (EMG) amplitude of the three major foot dorsiflexor muscles (tibialis anterior (TA), extensor digitorum longus (EDL), extensor hallucis longus (EHL)) during isometric foot dorsiflexion at different intensities. Methods In a cross-sectional study, forty-one subjects performed foot dorsiflexion at 100%, 75%, 50% and 25% of maximal voluntary contractions (MVC) with the hip and knee flexed 90° and the ankle in neutral position (90° between leg and foot). Three foot dorsiflexions were performed for each intensity. Outcome variables were: maximum (100% MVC) and relative torque (75%, 50%, 25% MVC), maximum and relative EMG amplitude. A linear regression analysis was calculated for each intensity of the isometric foot dorsiflexion. Results The degree of torque variation (dependent variable) from the independent variables explain (EMG amplitude of the three major foot dorsiflexor muscles) the increases when the foot dorsiflexion intensity is increased, with values of R 2 that range from 0.194 (during 25% MVC) to 0.753 (during 100% MVC). The reliability of the outcome variables was excellent. Conclusion The EMG amplitude of the three main foot dorsiflexors exhibited more variance in the dependent variable (torque) when foot dorsiflexion intensity increases. [ABSTRACT FROM AUTHOR]

Skeletal muscles of the rat anterior crural compartment are mechanically connected by epimuscular myofascial connections, but the relevance for mechanical muscle function within physiological ranges of joint motion is unclear. We evaluated the net effect at the ankle joint of epimuscular myofascial connections between tibialis anterior (TA) and extensor digitorum longus (EDL) muscles in the rat ( n =8) and determined which anatomical structures may mediate such epimuscular mechanical interactions. We assessed (1) effects of knee angle (i.e. changes in EDL length and position relative to TA) and interactions of knee angle with fasciotomy and proximal EDL tenotomy on TA ankle moment and (2) the effect of knee angle on TA and EDL ankle moment summation. Knee angle was varied between 60° and 130°. Ankle angle was kept constant (90°). TA and EDL were excited individually and simultaneously (TA&EDL). The mathematical sum of individual TA and EDL moments was compared with the moment exerted by TA&EDL to assess the extent of non-additive ankle moment summation. Magnitude of TA ankle moment was not affected by knee angle, but frontal plane moment direction was. However, dissections indicated that this was not caused by the compartmental fascia or EDL length changes. Moment summation was non-additive in magnitude (+1.1±1.1% mean±s.d.) and frontal plane direction. The latter was affected by knee angle and ranged from +0.2±0.3° at 60° to +1.1±0.6° at 130°. As the net effects found were very limited, we conclude that myofascial connections between muscles in the anterior crural compartment have limited mechanical relevance during normal movement. [ABSTRACT FROM AUTHOR]

Compared with the extensor digitorum longus (EDL) muscle of control rats (C), the EDL muscle of rats fed a low-protein, high-carbohydrate diet (LPHC) showed a 36% reduction in mass. Muscle mass is determined by the balance between protein synthesis and proteolysis; thus, the aim of this work was to evaluate the components involved in these processes. Compared with the muscle from C rats, the EDL muscle from LPHC diet-fed rats showed a reduction (34%) in the in vitro basal protein synthesis and a 22% reduction in the in vitro basal proteolysis suggesting that the reduction in the mass can be associated with a change in the rate of the two processes. Soon after euthanasia, in the EDL muscles of the rats fed the LPHC diet for 15days, the activity of caspase-3 and that of components of the ubiquitin-proteasome system (atrogin-1 content and chymotrypsin-like activity) were decreased. The phosphorylation of p70(S6K) and 4E-BP1, proteins involved in protein synthesis, was also decreased. We observed an increase in the insulin-stimulated protein content of p-Akt. Thus, the higher insulin sensitivity in the EDL muscle of LPHC rats seemed to contribute to the lower proteolysis in LPHC rats. However, even with the higher insulin sensitivity, the reduction in p-E4-BP1 and p70(S6K) indicates a reduction in protein synthesis, showing that factors other than insulin can have a greater effect on the control of protein synthesis. [ABSTRACT FROM AUTHOR]

Bothrops jararacussu venom drastically decreases sarcoplasmic Ca 2+ -ATPase (SERCA) protein expression in vivo and inhibits its activity in vitro , in contrast to a slight increase of Na + /K + -ATPase expression in murine EDL. We investigated the effect of myotoxins bothropstoxin-I and/or -II (BthTX-I, BthTX-II and BthTX-I+II) on this model. No changes were seen in SERCA1, SERCA2 and Na + /K + -ATPase α1 protein expression as well as 2+ Ca-ATPase activity, but BthTX-II (1 μg/g) reduced Na + /K + -ATPase α2 expression by 50% one day after perimuscular injection. Interestingly, BthTX-II inhibited Ca 2+ -ATPase activity (IC 50 around 6 nM). Our findings suggest that only BthTX-II affects ion transport ATPases, being a potent SERCA inhibitor and a putative target for antivenom drug development. [ABSTRACT FROM AUTHOR]

Abstract: Background: Statins are the most commonly used drugs for the treatment of hypercholesterolemia. Their most frequent side effect is myotoxicity. To date, it remains unclear whether statins preferentially induce myotoxicity in fast- or in slow-twitch muscles. Therefore, we investigated these effects on fast- (extensor digitorum longus; EDL), slow- (soleus; SOL), and mixed-twitch muscles (diaphragm; DIA) in rats by comparing their contractile and molecular structural properties. Methods: Simvastatin-induced functional changes were determined by muscle contraction measurements, and drug-induced molecular changes were investigated using Fourier transform infrared (FTIR) and attenuated total reflectance (ATR) FTIR spectroscopy. Results: With simvastatin administration (30days, 50mg/kg), a depression in the force–frequency curves in all muscles was observed, indicating the impairment of muscle contractility; however, the EDL and DIA muscles were affected more severely than the SOL muscle. Spectroscopic findings also showed a decrease in protein, glycogen, nucleic acid, lipid content and an increase in lipid order and lipid dynamics in the simvastatin-treated muscles. The lipid order and dynamics directly affect membrane thickness. Therefore, the kinetics and functions of membrane ion channels were also affected, contributing to the statin-induced impairment of muscle contractility. Furthermore, a reduction in α-helix and β-sheet and an increase in random coil, aggregated and antiparallel β-sheet were observed, indicating the protein denaturation. Spectral studies showed that the extent of molecular structural alterations in the muscles following simvastatin administration was in the order EDL>DIA>SOL. Conclusions: Simvastatin-induced structural and functional alterations are more profound in the fast-twitch than in the slow-twitch muscles. General significance: Myotoxic effects of simvastatin are primarily observed in the fast-twitch muscles. [Copyright &y& Elsevier]

Abstract: The purpose of this study is to test the hypothesis that muscle fibers are protected from undue atrophy in hibernating dauria ground squirrels (Spermophilus dauricus, Brandt). Muscle mass, fiber cross sectional area (CSA, video analysis) and fiber type distribution (m-ATPase staining) were determined in extensor digitorum longus (EDL) muscle from non-hibernating control animals (Pre-H), from animals who hibernated for one (H1) or two (H2) months, and from animals 2–4days after arousal (Post-H; N=8 each). Muscle wet weight decreased less than body weight in hibernating animals, resulting in a steady increase in muscle-to-body mass ratio (+37% in Post-H compared to Pre-H, p<0.001). In the Pre-H group, Type I (6.3±2.0%) and II (93.7±2.0%) fiber CSAs were 1719±201 and 2261±287 μm2, respectively. There was a tendency (n.s.) of larger CSA of type I in hibernators compared to pre-H. In the Post-H group, fiber CSA and type distribution were not different from Pre-H. We are the first to report data on EDL fiber type distribution and confirm a protective effect that prevents muscle atrophy in spite of prolonged disuse during hibernation in dauria ground squirrels. [Copyright &y& Elsevier]

Abstract: Objective: The main goal of the present study was to investigate the effects of a low-protein diet during gestation on the biomechanical properties of skeletal muscle of offspring rats. Methods: Male Wistar rats were divided into two groups according to their mothers’ diet during pregnancy: a control group (mothers fed with 17% protein) and a low-protein group (mothers fed with 7.8% protein; UN). At birth, all mothers received a standardized meal ad libitum. When the rats were 25 and 90 d old, the soleus and extensor digitorum longus (EDL) muscles were removed from the pups. An analysis of the contractile and series elastic component properties was carried out on both muscles. Histochemical analysis was likewise performed. Results: Group UN presented muscle wasting and diminution of maximum twitch and tetanic tension on the muscle at 25 and 90 d of life. There was an increase in maximal shortening velocity in the soleus and EDL muscles at 25 and 90 d in group UN. Series elastic component stiffness was increased in the soleus muscle, although a diminution of series elastic component stiffness was observed in the EDL at 25 d. With regard to the analysis of the muscle fiber proportions at 25 and 90 d, the UN group presented an increase in the IIa fibers in the soleus, whereas there was an increase in the IIb fibers and a diminution in the IIa fibers in the EDL. Conclusion: Low-protein intake during a critical period of development induces changes in the structure and function of skeletal muscle. Such changes may compromise an animal’s posture and locomotion. [Copyright &y& Elsevier]

The purposes of the present study were (1) to develop an implantable device capable of being pre-programmed to generate a protocol of chronic contractions in denervated hind-limb muscles of rats, and (2) to verify the design by implanting the stimulators for five weeks in rats to identify a protocol of stimulation that maintains muscle mass and maximum force in stimulated–denervated extensor digitorum longus (EDL) muscles. This implantable stimulator system did not hinder animal movement or hygiene, and enabled the animals to be housed in regular animal facilities, since neither external equipment nor an externally generated magnetic field was required. The pre-programmable microcontroller allows detailed basic research into the cellular and tissue response to different stimulation protocols. The micropower design of the battery powered device enabled chronic stimulation of denervated EDL muscles for the five weeks of this initial study. Stimulation protocols of 9–11 V pulse amplitude, 0.4 ms bipolar pulse width, 100 Hz, 20 pulses per contraction, and 100 or 300 contractions generated per day maintained muscle mass and maximum force in denervated EDL muscles of rats at values near control values for innervated muscles. [Copyright &y& Elsevier]

The aim of this study was to investigate if the Na+-channel activating alkaloid veratrine is able to change the oxidative and m-ATPase activities of a fast-twitch glycolytic muscle (EDL, extensor digitorum longus) and slow-twitch oxidative muscle (SOL, soleus) in mice. Oxidative fibers and glycolytic fibers were more sensitive to veratrine than oxidative-glycolytic fibers 15, 30 and 60 min after the i.m. injection of veratrine (10 ng/kg) with both showing an increase in their metabolic activity in both muscles. In EDL, the m-ATPase reaction revealed a significant (p<0.001) decrease (50%) in the number of type IIB fibers after 30 min while the number of type I fibers increased by 550%. Type I fibers decreased from 34% in control SOL to 17% (50% decrease) in veratrinized muscles, with a 10% decrease in type IIA fibers within 15 min. A third type of fiber appeared in SOL veratrinized muscle, which accounted for 28% of the fibers. Our work gives evidence that the changes in the percentage of the fiber types induced by veratrine may be the result, at least partially, from a direct effect of veratrine on muscle fibers and else from an interaction with the muscle type influencing distinctively the response of a same fiber type. Based on the results obtained in the present study the alterations in EDL may be related to the higher number of Na+ channels present in this muscle whereas those in SOL may involve an action of veratrine on mitochondria. Although it is unlikely that the shift of enzymes activities induced by veratrine involves genotypic expression changes an alternative explanation for the findings cannot be substantiated by the present experimental approach. [Copyright &y& Elsevier]

Skeletal muscles ensure the mobility of mammals and are complex natural fiber–matrix–composites with a hierarchical microstructure. In this work, we analyze the muscle's mechanical behavior on the level of fascicles and muscle fibers. We introduce continuum mechanics hyperelastic material models for the connective tissue endomysium and the embedded muscle fibers. The coupled electrical, chemical and mechanical processes taking place in activated contracting muscle fibers are captured including the temporal change of the activation level and the spatial propagation of the activation potential in fibers. In our model, we investigate the material behavior of fascicle, fiber and endomysium in the fiber direction and examine interactions between muscle fiber and endomysium by considering the temporal and spatial change of muscle fiber activation. In addition, a loading case of normal and shear forces is applied to analyze the fiber lifting force and the lifting height of unipennate muscles with different pennation angles. Moreover, the development of local stresses and strains in fibers and endomysium for different strains are studied. The simulation results allow to identify regions in high risk of damage. Optimal arrangements of unipennate muscle microstructure are found for either very small or very large pennation angles. [ABSTRACT FROM AUTHOR]

A variety of surgical procedures exist for the correction of hammertoe deformities, and several different methods of flexor tendon transfer have been described for the correction of hammertoes associated with extension contracture of the corresponding metatarsophalangeal joint. In the present report, we have described a variation of flexor tendon tenodesis we have found useful. [ABSTRACT FROM AUTHOR]

Investigating protein abundance profiles is important to understand the differences in the slow and fast skeletal muscle characteristics. The profiles in soleus (Sol) and extensor digitorum longus (EDL) muscles in mice exposed to 1 g or 3 g for 28 d were compared. The biological implications of the profiles revealed that hypergravity exposure activated a larger number of pathways involved in protein synthesis in Sol. In contrast, the inactivation of signalling pathways involved in oxidative phosphorylation were conspicuous in EDL. These results suggested that the reactivity of molecular pathways in Sol and EDL differed. Additionally, the levels of spermidine synthase and spermidine, an important polyamine for cell growth, increased in both muscles following hypergravity exposure, whereas the level of spermine oxidase (SMOX) increased in EDL alone. The SMOX level was negatively correlated with spermine content, which is involved in muscle atrophy, and was higher in EDL than Sol, even in the 1 g group. These results indicated that the contribution of SMOX to the regulation of spermidine and spermine contents in Sol and EDL differed. However, contrary to expectations, the difference in the SMOX level did not have a significant impact on the growth of these muscles following hypergravity exposure. The skeletal muscle-specific protein abundance profiles result in differences in the characteristics of slow and fast skeletal muscles. We investigated differences in the profiles in mouse slow-twitch Sol and fast-twitch EDL muscles following 28-d of 1 g and 3 g exposure by LC-MS/MS analysis and label-free quantitation. A two-step solubilisation of the skeletal muscle proteins increased the coverage of proteins identified by LC-MS/MS analysis. Additionally, this method reduced the complexity of samples more easily than protein or peptide fractionation by SDS-PAGE and offline HPLC while maintaining the high operability of samples and was reproducible. A larger number of hypergravity-responsive proteins as well as a prominent increase in the wet weights was observed in Sol than EDL muscles. The biological implications of the difference in the protein abundance profiles in 1 g and 3 g groups revealed that the reactivity of each molecular pathway in Sol and EDL muscles to hypergravity exposure differed significantly. In addition, we found that the biosynthetic and interconversion pathway of polyamines, essential factors for cell growth and survival in mammals, was responsive to hypergravity exposure; spermidine and spermine contents in Sol and EDL muscles were regulated by different mechanisms even in the 1 g group. However, our results indicated that the difference in the mechanism regulating polyamine contents is unlikely to have a significant effect on the differences in Sol and EDL muscle growth following hypergravity exposure. Unlabelled Image • Proteins in Sol and EDL muscles were extracted by a two-step solubilisation method. • Protein abundance profiles in each muscle changed following 28-d exposure to 3 g. • Pathways involved in protein synthesis were activated prominently in Sol muscles. • Pathways involved in oxidative phosphorylation were inactivated in EDL muscles. • Polyamine contents in Sol and EDL muscles were regulated differently via SMOX. [ABSTRACT FROM AUTHOR]

Autograft tendon harvested from the long toe extensors are of great utility as intercalary grafts in upper extremity reconstruction. However, standard full-length harvest is complicated by the presence of extensor retinacula and multiple juncturae between adjacent extensors, which often necessitate extensive dissection, increasing the potential for morbidity. We describe a modified technique for partial harvest of the long toe extensors, which is performed entirely proximal to the superior extensor retinaculum. This technique requires a single incision and provides adequate length of graft for the majority of forearm to fingertip reconstructions. The technique is described in the context of our preliminary cadaver findings, with a case example provided to further illustrate the utility of this technique. [ABSTRACT FROM AUTHOR]

Abstract: The extensor digitorum longus muscle (EDL) arises from the upper three-quarters of the extensor surface of the fibula, the interosseous septum and from a small area of the tibia across the superior tibiofibular joint. It forms its four tendons which are restrained by the superior and inferior extensor retinacula. The two retinacula prevent the EDL and extensor hallucis longus (EHL) tendons from bow stringing. The inferior extensor retinaculum also contributes to the stability of the subtalar joint. Extensor tendoscopy has been performed in 3 patients and no neural injury was noted. [Copyright &y& Elsevier]