Literatura científica selecionada sobre o tema "Fascicle mechanics"
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Artigos de revistas sobre o assunto "Fascicle mechanics"
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Wakeling, James M., Meghan Jackman e Ana I. Namburete. "The Effect of External Compression on the Mechanics of Muscle Contraction". Journal of Applied Biomechanics 29, n.º 3 (junho de 2013): 360–64. http://dx.doi.org/10.1123/jab.29.3.360.
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The velocity at which a muscle fascicle will shorten, and hence the force that it can develop, depends on its gearing within the muscle belly. Muscle fascicle length depends on both its pennation and the thickness of the muscle. It was expected that external compression would reduce the muscle thickness and pennation and thus cause a reduction to the gearing of the fascicles relative to the muscle belly. Structural properties of the medial gastrocnemius muscle were visualized using B-mode ultrasound in six subjects. Measurements were taken during cyclical isotonic contractions at three different ankle torques and with the application of no, one, or two elastic compression bandages to the lower leg. Ankle torques and angular velocities were unaffected by the external compression. External compression did, however, reduce the muscle thickness and the fascicle pennation and resulted in a decrease in the gearing within the muscle belly. Reductions in gearing would result in an increase in the muscle fascicle shortening velocity that would reduce the force-generating potential of the fascicles. It is suggested that externally applied compression should not be considered a way to enhance muscle performance when based on the structural mechanics.
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Brennan, Scott F., Andrew G. Cresswell, Dominic J. Farris e Glen A. Lichtwark. "The effect of muscle-tendon unit vs. fascicle analyses on vastus lateralis force-generating capacity during constant power output cycling with variable cadence". Journal of Applied Physiology 124, n.º 4 (1 de abril de 2018): 993–1002. http://dx.doi.org/10.1152/japplphysiol.00356.2017.
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The maximum force-generating capacity of a muscle is dependent on the lengths and velocities of its contractile apparatus. Muscle-tendon unit (MTU) length changes can be estimated from joint kinematics; however, contractile element length changes are more difficult to predict during dynamic contractions. The aim of this study was to compare vastus lateralis (VL) MTU and fascicle level force-length and force-velocity relationships, and dynamic muscle function while cycling at a constant submaximal power output (2.5 W/kg) with different cadences. We hypothesized that manipulating cadence at a constant power output would not affect VL MTU shortening, but significantly affect VL fascicle shortening. Furthermore, these differences would affect the predicted force capacity of the muscle. Using an isokinetic dynamometer and B-mode ultrasound (US), we determined the force-length and force-velocity properties of the VL MTU and its fascicles. In addition, three-dimensional kinematics and kinetics of the lower limb, as well as US images of VL fascicles were collected during submaximal cycling at cadences of 40, 60, 80, and 100 rotations per minute. Ultrasound measures revealed a significant increase in fascicle shortening as cadence decreased (84% increase across all conditions, P < 0.01), whereas there were no significant differences in MTU lengths across any of the cycling conditions (maximum of 6%). The MTU analysis resulted in greater predicted force capacity across all conditions relative to the force-velocity relationship ( P < 0.01). These results reinforce the need to determine muscle mechanics in terms of separate contractile element and connective tissue length changes during isokinetic contractions, as well as dynamic movements like cycling. NEW & NOTEWORTHY We demonstrate that vastus lateralis (VL) muscle tendon unit (MTU) length changes do not adequately reflect the underlying fascicle mechanics during cycling. When examined across different pedaling cadence conditions, the force-generating potential measured only at the level of MTU (or joint) overestimated the maximum force capacity of VL compared with analysis using fascicle level data.
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Farris, Dominic James, Benjamin D. Robertson e Gregory S. Sawicki. "Elastic ankle exoskeletons reduce soleus muscle force but not work in human hopping". Journal of Applied Physiology 115, n.º 5 (1 de setembro de 2013): 579–85. http://dx.doi.org/10.1152/japplphysiol.00253.2013.
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Inspired by elastic energy storage and return in tendons of human leg muscle-tendon units (MTU), exoskeletons often place a spring in parallel with an MTU to assist the MTU. However, this might perturb the normally efficient MTU mechanics and actually increase active muscle mechanical work. This study tested the effects of elastic parallel assistance on MTU mechanics. Participants hopped with and without spring-loaded ankle exoskeletons that assisted plantar flexion. An inverse dynamics analysis, combined with in vivo ultrasound imaging of soleus fascicles and surface electromyography, was used to determine muscle-tendon mechanics and activations. Whole body net metabolic power was obtained from indirect calorimetry. When hopping with spring-loaded exoskeletons, soleus activation was reduced (30–70%) and so was the magnitude of soleus force (peak force reduced by 30%) and the average rate of soleus force generation (by 50%). Although forces were lower, average positive fascicle power remained unchanged, owing to increased fascicle excursion (+4–5 mm). Net metabolic power was reduced with exoskeleton assistance (19%). These findings highlighted that parallel assistance to a muscle with appreciable series elasticity may have some negative consequences, and that the metabolic cost associated with generating force may be more pronounced than the cost of doing work for these muscles.
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De Brito Fontana, Heiliane, e Walter Herzog. "Fascicle shortening upon activation in voluntary human muscle contractions". Brazilian Journal of Motor Behavior 17, n.º 5 (30 de setembro de 2023): 238–45. http://dx.doi.org/10.20338/bjmb.v17i5.380.
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BACKGROUND: The dependence of fascicle length on complex interactions with joint angle and force challenges the interpretation of in vivo joint mechanics, muscle mechanical properties, contractile behavior, and muscle function. AIM: The purpose of this study was to determine the complex interaction between muscle activation, joint angle, and fascicle length for isometric contractions of the human vastus lateralis muscle (VL). METHOD: Knee extensor torques, joint angles, EMG activation, and fascicle lengths were determined in nine healthy subjects during maximal and submaximal isometric contractions. RESULTS: Fascicle shortening during isometric contractions depended on muscle-tendon unit length/joint angle and activation, reaching a maximum between angles where VL had its maximum force potential and minimum resistance to fascicle shortening. Maximal fascicle shortening shifted to shorter muscle-tendon unit lengths with decreasing activation. CONCLUSION: Fascicle shortening upon activation depends crucially on the force generating potential and stiffness of the muscle and can reach 30% of the resting fascicle length. Not accounting for the complex interactions between muscle length, force potential, muscle structure, and muscle stiffness has led to erroneous interpretations of the function and properties of healthy and diseased muscles.
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Lai, Adrian, Anthony G. Schache, Nicholas A. T. Brown e Marcus G. Pandy. "Human ankle plantar flexor muscle–tendon mechanics and energetics during maximum acceleration sprinting". Journal of The Royal Society Interface 13, n.º 121 (agosto de 2016): 20160391. http://dx.doi.org/10.1098/rsif.2016.0391.
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Tendon elastic strain energy is the dominant contributor to muscle–tendon work during steady-state running. Does this behaviour also occur for sprint accelerations? We used experimental data and computational modelling to quantify muscle fascicle work and tendon elastic strain energy for the human ankle plantar flexors (specifically soleus and medial gastrocnemius) for multiple foot contacts of a maximal sprint as well as for running at a steady-state speed. Positive work done by the soleus and medial gastrocnemius muscle fascicles decreased incrementally throughout the maximal sprint and both muscles performed more work for the first foot contact of the maximal sprint (FC1) compared with steady-state running at 5 m s −1 (SS5). However, the differences in tendon strain energy for both muscles were negligible throughout the maximal sprint and when comparing FC1 to SS5. Consequently, the contribution of muscle fascicle work to stored tendon elastic strain energy was greater for FC1 compared with subsequent foot contacts of the maximal sprint and compared with SS5. We conclude that tendon elastic strain energy in the ankle plantar flexors is just as vital at the start of a maximal sprint as it is at the end, and as it is for running at a constant speed.
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Roberts, T. J., M. S. Chen e C. R. Taylor. "Energetics of bipedal running. II. Limb design and running mechanics." Journal of Experimental Biology 201, n.º 19 (1 de outubro de 1998): 2753–62. http://dx.doi.org/10.1242/jeb.201.19.2753.
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Compared with quadrupeds, bipedal runners of the same weight have longer legs, take longer steps and can presumably use slower, more economical muscle fibers. One might predict that bipedal running is less expensive, but it is not. We hypothesized that bipeds recruit a larger volume of muscle to support their weight, eliminating the potential economy of longer legs and slower steps. To test our hypothesis, we calculated the relative volume of muscle needed to support body weight over a stride in small dogs (Canis familiaris) and wild turkeys (Meleagris gallopavo) of the same weight. First, we confirmed that turkeys and dogs use approximately the same amount of energy to run at the same speed, and found that turkeys take 1. 8-fold longer steps. Higher muscle forces and/or longer muscle fibers would require a greater volume of active muscle, since muscle volume is proportional to the product of force and fascicle length. We measured both mean fascicle length and mean mechanical advantage for limb extensor muscles. Turkeys generated approximately the same total muscle force to support their weight during running and used muscle fascicles that are on average 2.1 times as long as in dogs, thus requiring a 2.5-fold greater active muscle volume. The greater volume appears to offset the economy of slower rates of force generation, supporting our hypothesis and providing a simple explanation for why it costs the same to run on two and four legs.
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Wakeling, James M., Katrin Uehli e Antra I. Rozitis. "Muscle fibre recruitment can respond to the mechanics of the muscle contraction". Journal of The Royal Society Interface 3, n.º 9 (10 de fevereiro de 2006): 533–44. http://dx.doi.org/10.1098/rsif.2006.0113.
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This study investigates the motor unit recruitment patterns between and within muscles of the triceps surae during cycling on a stationary ergometer at a range of pedal speeds and resistances. Muscle activity was measured from the soleus (SOL), medial gastrocnemius (MG) and lateral gastrocnemius (LG) using surface electromyography (EMG) and quantified using wavelet and principal component analysis. Muscle fascicle strain rates were quantified using ultrasonography, and the muscle–tendon unit lengths were calculated from the segmental kinematics. The EMG intensities showed that the body uses the SOL relatively more for the higher-force, lower-velocity contractions than the MG and LG. The EMG spectra showed a shift to higher frequencies at faster muscle fascicle strain rates for MG: these shifts were independent of the level of muscle activity, the locomotor load and the muscle fascicle strain. These results indicated that a selective recruitment of the faster motor units occurred within the MG muscle in response to the increasing muscle fascicle strain rates. This preferential recruitment of the faster fibres for the faster tasks indicates that in some circumstances motor unit recruitment during locomotion can match the contractile properties of the muscle fibres to the mechanical demands of the contraction.
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Shin, David D., John A. Hodgson, V. Reggie Edgerton e Shantanu Sinha. "In vivo intramuscular fascicle-aponeuroses dynamics of the human medial gastrocnemius during plantarflexion and dorsiflexion of the foot". Journal of Applied Physiology 107, n.º 4 (outubro de 2009): 1276–84. http://dx.doi.org/10.1152/japplphysiol.91598.2008.
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Velocity-encoded phase-contrast magnetic resonance (MR) imaging techniques and a computer-controlled MR-compatible foot pedal device were used to investigate the medial gastrocnemius muscle and aponeurosis deformations during passive and active eccentric movements of the plantarflexors. Intrafascicular strain, measured as the ratio of strain in the fascicle segment at its insertion to strain at its origin, was nonuniform along the proximodistal axis of the muscle ( P < 0.01), progressively increasing from the proximal to distal direction. The high intrafascicular strain regions appeared to correlate with the muscle regions that are likely to encounter high stress concentrations, i.e., the regions where the muscle physiological cross section decreases close to the tendons. The architectural gear ratio, i.e., the mechanical amplification ratio of fascicle length displacement to that of tendon/aponeuroses in a pennate muscle, also exhibited significant regional differences, with the highest ratios in the proximal region of the muscle accompanied by a higher initial pennation angle and a larger range of fascicular rotation about the origin. Values close to unity in the distal region of the muscle suggest that the aponeurosis separation may decrease in this region. Fascicle length and pennation angle changes were significantly influenced by force generation in the muscle, probably due to a shortening of the loaded muscle fibers relative to a passive condition. Overall, our data illustrate significant proximodistal intramuscular heterogeneity as supported by a regionally variable end-to-end strain ratio of fascicles and angle changes in the medial gastrocnemius muscle during passive and active ankle movements. These observations emphasize the need to reassess current conceptual models of muscle-tendon mechanics.
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Valadão, P., S. Kurokawa, T. Finni e J. Avela. "Effects of muscle action type on corticospinal excitability and triceps surae muscle-tendon mechanics". Journal of Neurophysiology 119, n.º 2 (1 de fevereiro de 2018): 563–72. http://dx.doi.org/10.1152/jn.00079.2017.
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This study investigated whether the specific motor control strategy reported for eccentric muscle actions is dependent on muscle mechanical behavior. Motor evoked potentials, Hoffman reflex (H-reflex), fascicle length, pennation angle, and fascicle velocity of soleus muscle were compared between isometric and two eccentric conditions. Ten volunteers performed maximal plantarflexion trials in isometric, slow eccentric (25°/s), and fast eccentric (100°/s) conditions, each in a different randomized testing session. H-reflex normalized by the preceding M wave (H/M) was depressed in both eccentric conditions compared with isometric ( P < 0.001), while no differences in fascicle length and pennation angle were found among conditions. Furthermore, although the fast eccentric condition had greater fascicle velocity than slow eccentric ( P = 0.001), there were no differences in H/M. There were no differences in motor evoked potential size between conditions, and silent period was shorter for both eccentric conditions compared with isometric ( P = 0.009). Taken together, the present results corroborate the hypothesis that the central nervous system has an unique activation strategy during eccentric muscle actions and suggest that sensory feedback does not play an important role in modulating these muscle actions. NEW & NOTEWORTHY The present study provides new insight into the motor control of eccentric muscle actions. It was demonstrated that task-dependent corticospinal excitability modulation does not seem to depend on sensory information processing. These findings support the hypothesis that the central nervous system has a unique activation strategy during eccentric muscle actions.
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Dabrowska, Sylwia, Krzysztof Grabowski e Andrzej Mlyniec. "Rehydration of the Tendon Fascicle Bundles Using Simulated Body Fluid Ensures Stable Mechanical Properties of the Samples". Materials 15, n.º 9 (21 de abril de 2022): 3033. http://dx.doi.org/10.3390/ma15093033.
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In this work, we investigate the influence of dehydration and subsequent rehydration of tendon fascicle bundles on their structural and mechanical properties by using distilled water, 0.9% NaCl, 10% NaCl, SBF, and double concentrated SBF (SBFx2). The properties of tendon fascicle bundles were investigated by means of uniaxial tests with relaxation periods and hysteresis for samples with various interfascicular matrix content, dissected from the anterior and posterior areas of bovine tendon. Uniaxial tests with relaxation periods and analysis of sample geometry and weight showed that dehydration alters the modulus of elasticity dependent on the interfascicular matrix content and influences the viscoelastic properties of tendon fascicle bundles. Tensile and relaxation tests revealed that changes resulting from excessive sample drying can be reversed by rehydration in an SBF bath solution for elastic strain range above the toe region. Rehydration in SBF solution led to minor differences in mechanical properties when compared to control samples. Moreover, anterior samples with greater interfascicular matrix content, despite their lower stiffness, are less sensitive to sample drying. The obtained results allow us to limit the discrepancies in the measurement of mechanical properties of wet biological samples and can be useful to researchers investigating soft tissue mechanics and the stability of transplant materials.
Teses / dissertações sobre o assunto "Fascicle mechanics"
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Tamiwa, Masami. "Dynamic Mechanical Characterisation of Rat-tail Tendon Fascicles". Thesis, Queen Mary, University of London, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.498180.
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Kim, Hyeon Yu Ph D. Massachusetts Institute of Technology. "Effect of mechanical stretching on the maturation of 3-D fascicle-like muscle tissue". Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/93828.
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Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2014.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 52-55).
Skeletal muscle is well known for a rapid adaptation to mechanical environmental changes. Understanding the effects of the mechanical stimulation such as stretching to muscle tissues is important for understanding the nature of muscle development and muscle diseases. While there are many reports studying the effects of stretching on 2-D cultures in vitro, few research groups have investigated their effects in 3-D muscle strips with high volumetric density. Here, we used the muscle strips that have fascicle-like shape, high volumetric density, and optimal alignment in 3-D. We present that the fascicle-like muscle tissue will have stronger performance and more matured structure in response to particular stimulation. We applied the static and cyclic stretching, electrical stimulation and two different co-stimulation. Both the static and cyclic stretching induced stronger cell-ECM adhesions of 3-D cultured muscle cells. The static tension at day 9 caused striated actin of the muscles, but the cyclic tension at day 1 caused weakening of actin structure with less alignment. Similarly, the stretching could affect other proteins, related to muscle development. Therefore, the effect of the stretching to the muscle tissue is highly time-dependent, and it is important to find optimal timing for efficient training. We also show that muscle performance by the co-stimulation is higher than by the electrical stimulation alone. Although conditions of the each mechanical and electrical stimuli were identical, the performances were changed only by phase shift between the two stimuli. We still do not know the exact mechanism, but our results support the potential use of high-performance engineered muscle tissues for moving bio-robots or drug testing platforms.
by Hyeon Yu Kim.
S.M.
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Neal, Devin Michael. "Elongated fascicle-inspired 3D tissues consisting of high-density, aligned, optogenetically excitable muscle tissue using sacrificial outer molding". Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/92166.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2014.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 80-89).
The majority of muscles, nerves, and tendons are composed of fiber-like fascicle morphology. Each fascicle has a) elongated cells highly aligned with the length of the construct, b) a high volumetric cell density, and c) a high length-to-width ratio with a diameter small enough to facilitate perfusion. Fiber-like fascicles are important building blocks for forming those tissues of various sizes and cross-sectional shapes, yet no effective technology is currently available for producing long and thin fascicle-like constructs with aligned, high-density cells. Here we present a method for molding cell-laden hydrogels that generate cylindrical tissue structures that are ~100 [mu]m in diameter with an extremely high length to diameter ratio (>100:1). Using this method we have successfully created skeletal muscle tissue with a high volumetric density (~50%) and perfect cell alignment along the axis. A new molding technique, Sacrificial Outer Molding, allows us to i) create long and thin cavities of desired shape in a mold that is solid at a low temperature, ii) release gelling agents from the sacrificial mold material after cellladen hydrogel is injected into fiber cavities, iii) generate a uniform axial tension between anchor points at both ends that promotes cell alignment and maturation, and iv) perfuse the tissue effectively by exposing it to media after melting the sacrificial outer mold at 37°C. Effects of key parameters and conditions, including initial cavity diameter, axial tension, and concentrations of hydrogel and gelling agent, upon tissue compaction, volumetric cell density, and cell alignment are presented. Furthermore, the tissue is characterized in a custom designed mechanical characterization system. Characterization has shown that an optimal diameter exists at which muscle constructs exhibit the greatest contraction performance, and that optical and electrical stimulation of optogenetic muscle cells result in similar performance if the tissue is developed sufficiently.
by Devin Michael Neal.
Ph. D.
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Robinson, M. W. "Mechanisms of benzimidazole resistance in the liver fluke, Fasciola hepatica". Thesis, Queen's University Belfast, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.273381.
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Savage, J. E. "Studies on the mechanism of resistance to triclabendazole in the liver fluke Fasciola hepatica". Thesis, Queen's University Belfast, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.546421.
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Devine, C. "Elucidation of the mechanism of resistance to triclabendazole in the liver fluke, Fasciola hepatica". Thesis, Queen's University Belfast, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.546044.
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Hollville, Enzo. "Impact du type de surface sur la réponse à l’exercice : du muscle au mouvement Interactions between fascicles and tendinous tissues in gastrocnemius medialis and vastus lateralis during drop landing How surface properties affect fascicle-tendon interactions during drop landing? Muscle-tendon interactions in jumping: influence of surface properties". Thesis, Sorbonne Paris Cité, 2019. http://www.theses.fr/2019USPCB018.
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Les propriétés des surfaces sportives peuvent impacter directement la performance et le risque de blessure en modulant la part d’énergie transmise à l'athlète lors de l'impact du pied sur la surface. Les pelouses naturelle et synthétique sont couramment utilisées sur les terrains de football et de rugby. Depuis quelques années, une nouvelle génération de pelouse dite naturelle renforcée a fait son apparition dans les clubs professionnels mais son influence sur la biomécanique du geste sportif est encore mal connue. Cette thèse vise à évaluer l'influence de trois types de surfaces (gazon naturel renforcée, gazon synthétique et tartan) sur les interactions muscle-tendon et les coordinations neuromusculaires des muscles gastrocnemius medialis (GM) et vastus lateralis (VL) lors de mouvements de réception uni et bilatérale ainsi que de saut. L’analyse des données échographiques dynamiques, de cinématique 2D et d’activité musculaire nous a permis de montrer que : i) les propriétés mécaniques des surfaces peuvent altérer les interactions entre les faisceaux musculaires et les tissus tendineux ainsi que l’amplitude d’activation musculaire ; ii) la pelouse naturelle renforcée semble avoir des propriétés plus optimales que la pelouse synthétique lors de sauts et réceptions ; iii) il existe des différences de comportement marquées entre le GM et VL qui dépendent du type de surface, du type de mouvement et de son intensité. Cela souligne l’importance de ne pas se limiter à l’étude des propriétés mécaniques des surface pour comprendre leur influence sur le mouvement sportif. Par ailleurs, l’étude des comportements musculo-tendineux in vivo en condition écologique permet de mieux comprendre les interactions complexes entre l’homme et la surfaceSports surface properties can substantially alter the overall performance and risk of injury. Surface mechanical properties influence the loading of the human musculoskeletal system by modulating the amount of foot-impact energy transmitted to the athlete. Natural grass and synthetic turf are commonly used pitches in football and rugby. More recently, reinforced natural grass technology has been used at the elite-level facilities, but its influence on player is not well defined. This thesis aimed at evaluating the influence of three different surfaces (reinforced natural grass, synthetic turf and athletic track) on the muscle-tendon interactions and neuromuscular coordination of gastrocnemius medialis (GM) and vastus lateralis (VL) muscles during landings and jumping tasks. Analysis of dynamic ultrasound imaging, 2D kinematics and electromyographic data showed that: i) surface mechanical properties influenced muscle-tendon interactions as well as the level of muscle activity; ii) the reinforced natural grass surface seems to optimize the muscular response during the movement and iii) GM and VL muscles displayed specific behaviors relative to the type of movement, its intensity and the type of surface. This emphasizes that the human response cannot be predicted by only analyzing the mechanical surface properties and highlights the important role of in vivo ecological testing to better understand player-surface interaction
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Ribeiro, Ana Paula. "Avaliação estática do complexo tornozelo-pé e padrões dinâmicos da distribuição da pressão plantar de corredores com e sem fasciite plantar". Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/5/5163/tde-27052010-164407/.
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A fasciite plantar é considerada a terceira doença mais comum em corredores. Apesar dessa alta prevalência, sua patogênese ainda é inconclusiva. Na literatura desalinhamento do retropé, mudanças na conformação do arco longitudinal plantar e um aumento da carga mecânica sobre os pés, têm sido embasados como fatores de risco para o desenvolvimento da fasciite plantar. No entanto, há uma escassez de estudos que investigaram estes fatores, durante a corrida. A maior parte da literatura investigou, especificamente, a marcha e os resultados apresentam-se controversos e ainda não claros, principalmente, em relação ao efeito da dor associada à doença. Para alívio da dor, a maioria dos tratamentos baseia-se na inserção de palmilhas, porém, há longo prazo, elas não impedem as recidivas dos sintomas. Isso pode ser justificado pela carência de bases científicas que melhor descrevam as características posturais do complexo tornozelo-pé e os padrões dinâmicos da carga plantar, durante a corrida, para que possam perpetuar uma maior eficácia deste tipo de tratamento. Assim, o objetivo geral desse estudo foi verificar a influência da fasciite plantar com e sem dor sobre o alinhamento do retropé e o arco longitudinal medial na postura ortostática bipodal, bem como a análise da distribuição da pressão plantar durante a corrida. Foram estudados 105 corredores adultos de ambos os sexos entre 20 a 55 anos. Destes 45 apresentavam fasciite plantar (30 com dor - FPS e 15 sem dor - FPA) e 60 eram corredores controles - GC. Para responder as questões científicas específicas foram realizados dois experimentos. O experimento um teve como objetivo específico avaliar a influência da fasciite plantar sintomática e assintomática sobre o alinhamento do retropé e o arco longitudinal medial durante a postura ortostática bipodal de corredores recreacionais. Para tanto, foram avaliadas, por meio da fotogrametria digital, duas medidas clínicas: ângulo do retropé e o arco longitudinal medial. O experimento dois teve como objetivo específico investigar e comparar a distribuição da pressão plantar de corredores com fasciite plantar sintomática e assintomática e corredores sem a presença da doença, durante a corrida. Para tanto, a distribuição da pressão plantar foi avaliada por meio de palmilhas capacitivas (Pedar X System) durante uma corrida de 40m a uma velocidade de 12km/h, utilizando um calçado esportivo padrão. A dor foi mensurada pela escala visual analógica. Para análise das variáveis biomecânicas da pressão o pé foi dividido em seis áreas: retropé lateral, central e medial, mediopé e antepé lateral e medial. Os principais resultados desse estudo mostraram que a fasciite plantar sintomática e assintomática não apresentou diferenças significativas no alinhamento em valgo do retropé, mas a condição de fasciite plantar influenciou no arco longitudinal medial, onde ambos os grupos com fasciite plantar (com e sem dor) apresentaram um arco mais elevado em relação ao controle. Já em relação às cargas plantares, durante a corrida, não houve diferença significativa nas variáveis: pico de pressão (p = 0,609), área de contato (p = 0,383), tempo de contato (p = 0,908) e integral da pressão (p = 0,504). Conclui-se que a fasciite plantar sintomática e assintomática não altera o alinhamento do retropé na postura ortostática bipodal e a distribuição da pressão plantar, durante a corrida. No entanto, a condição fasciite plantar, independente do sintoma de dor, associa-se com um aumento do arco longitudinal medial na população de corredoresThe plantar fasciitis has been the third most common disease in runners. Despite this high prevalence, its pathogenesis is still inconclusive. In literature, the rearfoot misalignment, changes in the conformation of longitudinal plantar arch and increased mechanical load on the feet, have been described as risk factors for developing of plantar fasciitis. However, there are few studies investigating these factors during the running. The most of the literature investigated the gait and the results are still controversial and unclear, mainly on the effect of pain associated with disease. For pain relief, most of the treatments are based on use of the insoles, however, they do not have long-term beneficial effects. This can be explained by the lack of scientific evidence that describe the characteristics of postural ankle-foot complex and dynamic load patterns on plantar surface during the running, thus, improve effectiveness this type of treatment. The general purpose of this study was to investigate the influence of plantar fasciitis with and without pain on the rearfoot alignment, longitudinal medial plantar arch in bipedal standing posture and on the plantar pressure distribution during the running. One hundred and five adult recreational runners of both sexes between 20 to 55 years old were studied. Of these, 45 had plantar fasciitis (symptomatic 30 SPF and asymptomatic 15 APF) and 60 controls runners CG. Two experiments were realized in order to respond the specific scientific questions. The first experiment had the specific purpose of verify the influence of plantar fasciitis symptomatic (with pain) and asymptomatic (without pain) on the rearfoot alignment and on the longitudinal medial plantar arch during bipedal standing posture of runners. Therefore, were evaluated by mean of digital photogrammetry, two clinical measures: the rearfoot angle and arch index. The experiment two aimed specifically to investigate and comparing the plantar pressure distribution in runners with plantar fasciitis symptomatic and asymptomatic and runners without plantar fasciitis during the running. Therefore, the plantar pressure distribution was measured by capacitive insoles (Pedar System X) during a running of 40 m at a speed of 12km/h, using a standard sport shoes. Pain was measured by visual analogue scale. For analysis of the pressure variables, the foot was divided into six areas: rearfoot lateral, central and medial; midfoot and forefoot medial and lateral. The principal results of this study showed that the symptomatic and asymptomatic plantar fasciitis do not show significant difference in the valgus rearfoot misalignment, but the condition of plantar fasciitis (symptomatic and asymptomatic) caused an increase of the longitudinal medial plantar arch compared to CG. In relation to the plantar loads during the running, there was no significant difference on pressure peak (p = 0.609), contact area (p = 0.383), contact time (p = 0.908) and pressure integral (p = 0.504). We concluded that the symptomatic and asymptomatic plantar fasciitis does not change the valgus rearfoot alignment during bipedal standing posture and the plantar pressure distribution during the running. However, the condition of symptomatic and asymptomatic plantar fasciitis showed an increase in the longitudinal medial plantar arch of recreational runners
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Gotti, Carlo. "Development and mechanical characterization of a biostable Nylon6.6 electrospun nanofibrous multiscale device for tendon and ligament replacement and simulation". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amslaurea.unibo.it/15708/.
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This thesis aims to investigate electrospun structures by means their production process and morpho-mechanical characterization. Considering the results obtained, the electrospun devices developed, will be useful for tendon and ligament tissue applications.
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Mulero, Stephen. "Développement d’outils d’écologie moléculaire pour un suivi intégratif des maladies transmises par les mollusques d’eau douce dans un contexte d’émergences et de changements globaux A Multiplex Rapid Diagnostic PCR (RD-PCR) approach for xenomonitoring of human and animal schistosomiases in a One Health context Genetic diversity and relationships of the liver fluke Fasciola hepatica (Trematoda) with native and introduced definitive and intermediate hosts Simultaneous genotyping of gastropods and their trematode parasites using Amplicon Sequencing Pre-zygotic isolation mechanisms between Schistosoma haematobium and Schistosoma bovis parasites: from mating interactions to differential gene expression". Thesis, Perpignan, 2020. http://www.theses.fr/2020PERP0023.
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Les changements globaux, qu’ils soient d’origine climatique ou anthropique ont diverses conséquences en santé humaine et animale, mais aussi sur les écosystèmes mondiaux. L’une des plus importantes est la modification des aires de répartitions géographiques des espèces et de celle des pathogènes qui leurs sont associés. C’est dans ce contexte que nous assistons ces dernières années à une recrudescence des cas d’émergences et de réémergences de maladies infectieuses dans le monde. Alors que les efforts de recherche menés dans ce domaine se focalisent principalement sur les maladies virales, les maladies transmises par les mollusques d’eau douce, qui affectent plus d’un milliard d’individus dans le monde, sont également sujettes à ces évènements d’émergences devenus fréquents. Cependant, l’étude de la dynamique des parasites associés à ces maladies se focalisent essentiellement sur le diagnostic et le traitement des hôtes définitifs, en particulier l’Homme. Toutefois, une telle approche ne permet pas de prévenir de la transmission de ces parasites à l’Homme et encore moins de prévenir d’un évènement d’émergence, et les outils actuels utilisés pour le suivi de ces parasites dans l’environnement sont difficilement applicables à large échelle. Ce travail de thèse se propose donc d’apporter une vision plus environnementale de la dynamique de ces maladies. Avec l’exemple de l’émergence de bilharziose urogénitale en Corse, nous avons analysé cette émergence en intégrant l’étude des traits d’histoire de vie du parasite tropical en cause, notamment sa thermo tolérance, ainsi que le rôle des hôtes intermédiaires mollusques et des hôtes définitifs sauvages et domestiques dans le maintien local du cycle parasitaire. Dans un second temps nous avons développé des outils de diagnostic par ADN environnemental pour la détection de mollusques hôtes dans l’environnement afin d’identifier les zones à risque d’émergence, ainsi que des outils de détection intramolluscal de schistosomes pour identifier les sites de transmission actif, et donc permettre un suivi environnemental des acteurs de ces maladies. Pour compléter ces approches, nous avons développé un outil plus généraliste de metabarcoding environnemental pour caractériser les communautés de mollusques d’eau douce, et initié le développement d’un outil similaire pour la caractérisation des communautés de trématodes, ceci afin d’étudier les interactions entre ces organismes. Enfin nous discutons de l’intégrations de tous ces éléments dans de nouvelles stratégies de contrôle à l’encontre de maladies transmises par les mollusques d’eau douceGlobal changes, whether climatic or anthropogenic, have various consequences in human and animal health, as well as for worldwide ecosystems. One of the most important is the modification of geographical ranges of species and those of their associated pathogens. It is in this context that in recent years we have witnessed a resurgence in the emergence and re-emergence of infectious diseases around the world. While research efforts in this field are mainly focused on viral diseases, freshwater snail-borne diseases, that affect more than 1 billion peoples around the world, are also subject to these outbreaks, which have become frequent. However, the study of the dynamics of parasites associated with these diseases focuses primarily on the diagnosis and treatment of the definitive hosts, particularly humans. Such an approach does not prevent the transmission of these parasites to humans and even less prevent an emergence event, and the existing tools used to monitor these parasites in the environment are difficult to apply at large scale. This thesis work, therefore aims to provide a more environmental vision of the dynamics of these diseases. With the example of the emergence of urogenital bilharziasis in Corsica, we analysed this emergence by integrating the study of the life history traits of the tropical parasite in question, particularly its thermo tolerance, as well as the role of mollusc intermediate hosts and wild and domestic definitive hosts in the local maintenance of the parasite lifecycle. In a second step, we have developed environmental DNA diagnostic tools for the detection of molluscs hosts in the environment in order to identify areas at risk of emergence, as well as tools for intramolluscal detection of schistosomes to identify active sites of transmission, and thus allow the environmental monitoring of the actors of these diseases. To complete these approaches, we have developed a more generalised environmental metabarcoding tool to characterise freshwater mollusc communities and initiated the development of a similar tool for the characterisation of trematode communities, in order to study the interactions between these organisms. Lastly, we discuss the integration of all these elements into new control strategies against snail-borne diseases
Livros sobre o assunto "Fascicle mechanics"
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Stecco, Luigi. Fascial manipulation for muscuskeletal pain. Padova, Italy: Piccin Nuova Libraria S.p.A., 2004.
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Misra, V. Peter, e Santiago Catania. EMG-guided botulinum toxin therapy. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780199688395.003.0026.
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This chapter explains the mechanism by which botulinum neurotoxin (BoNT) causes its neuromuscular paralytic effects, and reviews the developments that led these effects to be harnessed therapeutically. It specifically focuses upon the conditions of dystonia and spasticity. Within the spectrum of these diseases, it discusses those situations where BoNT injections are the treatment of choice. The very accurate targeting of BoNT into specific muscles in many situations is both desirable and crucial in some situations BoNT’s therapeutic neuroparalytic effect may need to be restricted to a single muscle fascicle.. In some cases, an inaccurately placed injection may be associated with unacceptable side effects. In order to achieve accuracy of BoNT injection delivery, intramuscular injections of BoNT aided by electromyography (EMG) guidance allows the very accurate targeting of specific muscles. The practical aspects related to the preparation of BoNT for injection and the methodology and techniques for injecting using EMG guidance are discussed. The importance of good anatomical knowledge and the relevant EMG techniques to target individual muscles are highlighted and applied to injection of muscles in different body areas. Finally, certain diagnostic neurophysiological tests, which may be useful for the management of some neurological conditions that are treated by BoNT are briefly discussed.
Capítulos de livros sobre o assunto "Fascicle mechanics"
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Chun, Keyoung Jin, e D. L. Butler. "Spatial Variation in Material Properties in Fascicle-Bone Units from Human Patellar Tendon". In Experimental Mechanics in Nano and Biotechnology, 797–802. Stafa: Trans Tech Publications Ltd., 2006. http://dx.doi.org/10.4028/0-87849-415-4.797.
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Bonaldi, Lorenza, Alice Berardo e Chiara Giulia Fontanella. "The Mechanical Behavior of the Fascial System". In Fascia, Function, and Medical Applications, 107–16. 2a ed. Boca Raton: CRC Press, 2024. http://dx.doi.org/10.1201/9781032675886-12.
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Robinson, Mark W., John P. Dalton, Sandra M. O'Neill e Sheila M. Donnelly. "Mechanisms of Immune Modulation by Fasciola hepatica: Importance for Vaccine Development and for Novel Immunotherapeutics". In Parasitic Helminths, 451–63. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, 2012. http://dx.doi.org/10.1002/9783527652969.ch27.
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Sarnat, Harvey B., e Laura Flores-Sarnat. "Cerebral Cortical Dysplasia or Dysgenesis". In Jasper's Basic Mechanisms of the Epilepsies, editado por Jeffrey L. Noebels, Massimo Avoli, Michael A. Rogawski, Annamaria Vezzani e Antonio V. Delgado-Escueta, 35–44. 5a ed. Oxford University PressNew York, 2024. http://dx.doi.org/10.1093/med/9780197549469.003.0003.
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Abstract Embryonic and fetal ontogenesis of the central nervous system is realized by genetically programmed developmental processes with precise timing of onset. Both anatomical development and timing are altered in brain malformations. Keratan sulfate (KS) proteoglycan is a key axonal pathfinding guide and insulator of tracts and fascicles within the central nervous system and an essential determinant of the equilibrium of excitation and inhibition at the level of the individual neuron during development. KS is selective by repelling glutamatergic axons and facilitating GABAergic axons at sites of synapse formation. Its demonstration by immunocytochemistry provides another perspective for understanding epileptogenesis at the cellular level in brain resections for epilepsy and at autopsy, including fetal tissues. Examples of malformations in which epileptogenesis is influenced by KS are polymicrogyria, schizencephaly, focal cortical dysplasias, holoprosencephaly, and Down syndrome.
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Wise, Steven P. "Human hemispheres". In Cortical Evolution in Primates, 251–78. Oxford University PressOxford, 2023. http://dx.doi.org/10.1093/oso/9780192868398.003.0014.
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Abstract A few new areas probably emerged in the human cortex, but the major development was a dramatic expansion of the typically layered areas (more commonly known as homotypical association cortex). Mainly because of their enlargement, the cortex expanded into the modern human size range, mostly in the past two million years. A transcortical network that includes connections between temporal and frontal cortex via the arcuate fascicle enlarged and reorganized. In addition, the hippocampus decreased in relative size during most of anthropoid evolution but increased during human evolution, which reflects new inputs and functions. The genetic mechanisms of cortical expansion include gene duplications that extend neural stem-cell proliferation and keep neurons in an immature state, thus increasing the number of dendritic spines and synapses. A within-gene deletion in the chimpanzee–human common ancestor promoted synaptogenesis in the prefrontal cortex.
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Viswanathan, Ashwin. "Pelvic/Visceral Cancer Pain". In Pain Neurosurgery, 113–18. Oxford University Press, 2019. http://dx.doi.org/10.1093/med/9780190887674.003.0014.
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The management of medically refractory cancer pain is a complex, multi-disciplinary effort. When optimal medical management has failed, neuroablative and neuromodulatory efforts can be used. While neuromodulation is an attractive option due its minimally invasive nature, neuroablation offers the advantage of high efficacy and the lack of maintenance or upkeep requirements. Punctate midline myelotomy is an ablative procedure targeting the ascending visceral pain pathway in the dorsal columns. The procedure can be performed through an open approach creating a mechanical lesion, or percutaneously via either a mechanical lesion or radiofrequency ablation. Careful attention to the spinal cord midline during lesion creation and attention to surgical technique, including an excellent fascial closure, can minimize potential complications.
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Kawai, Tomonori. "Shear Wave Elastography for Chronic Musculoskeletal Problem". In Elastography - Applications in Clinical Medicine [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.102024.
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Shear wave elastography is a new noninvasive tool for the analysis of the biomechanical properties of the muscles in healthy and pathological conditions. Shear wave elastography is currently considered as a promising real-time visualization tool for quantifying explicitly the mechanical properties of soft tissues in sports medicine including muscle strain injury (MSI). This chapter shows utilizing diagnostic tools of magnetic resonance imaging, B mode ultrasound (US), and shear wave elastography in both acute and chronic phases. Also, the proposal for this chapter is to indicate the possibility of utilizing shear wave elastography for musculoskeletal injury, not only properties of the muscle but also fascial tissues. It introduces the relationship between previous muscle strain injury and local soft tissue stiffness, and we assessed the mechanical properties of soft tissues from a clinical perspective.
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Wong, Agnes. "Nuclear and Infranuclear Ocular Motor Disorders". In Eye Movement Disorders. Oxford University Press, 2008. http://dx.doi.org/10.1093/oso/9780195324266.003.0021.
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Binocular diplopia is usually caused by strabismus, whereas monocular diplopia is usually caused by ocular diseases. Incomitant diplopia is usually caused by an acquired strabismus resulting from abnormal innervation or mechanical restriction. The oculomotor (third) nerve: ■ Innervates the medial rectus, superior rectus, inferior rectus, inferior oblique, and levator palpebrae muscles ■ Carries parasympathetic fibers to the iris sphincter and the ciliary body. ■ Common causes of third nerve palsy: Adults: aneurysms, vascular disease (including ischemia, diabetes, hypertension, and inflammatory arteritis), trauma, migraine Children: birth trauma, accidental trauma, neonatal hypoxia, migraine The third nerve originates from the oculomotor nucleus complex, which lies at the ventral border of the periaqueductal gray matter in the midbrain. The nerve fascicle passes ventrally through the medial longitudinal fasciculus, the tegmentum, the red nucleus, and the substantia nigra, and finally emerges from the cerebral peduncle to form the oculomotor nerve trunk, which lies between the superior cerebellar and posterior cerebral arteries. The nerve then passes through the subarachnoid space, running beneath the free edge of the tentorium. It continues lateral to the posterior communicating artery and below the temporal lobe uncus, where it runs over the petroclinoid ligament. It pierces the dura mater at the top of the clivus to enter the cavernous sinus. Within the cavernous sinus, the nerve runs along the lateral wall of the sinus together with the trochlear nerve and the ophthalmic (V1) and maxillary (V2) divisions of the trigeminal nerve. As it leaves the cavernous sinus, it divides into the superior and inferior divisions, which pass through the superior orbital fissure, and enters the orbit within the annulus of Zinn. Within the orbit, the smaller superior division runs lateral to the optic nerve and ophthalmic artery and supplies the superior rectus and levator palpebrae muscles. The larger inferior division supplies the medial rectus, inferior rectus, and inferior oblique muscles, as well as the iris sphincter and ciliary body.
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"Mechanisms of Immune Modulation by Fasciola Hepatica: The Impact of Innate Immune Cells on the Developing Adaptive Immune Response". In Immune Response to Parasitic Infections, editado por Sandra M. O'Neill e Sheila Donnelly, 51–67. BENTHAM SCIENCE PUBLISHERS, 2014. http://dx.doi.org/10.2174/9781608059850114020006.
Texto completo da fonteTrabalhos de conferências sobre o assunto "Fascicle mechanics"
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Robinson, Paul S., Tony W. Lin, Paul R. Reynolds, Kathleen A. Derwin, Renato V. Iozzo e Louis J. Soslowsky. "Potential Roles for Collagen and Decorin in Strain Rate Sensitive Tendon Fascicle Mechanical Properties". In ASME 2001 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/imece2001/bed-23064.
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Abstract Little is known about the contributions of specific extracellular matrix components of tendon to the tissue’s mechanical properties. Type I collagen, given its abundance and association into long fibrils, is thought to dominate the elastic properties of tendon. Proteoglycans (PGs) are believed to provide elasticity through their potential role in transferring stress between discontinuous fibrils, as well as viscoelasticity via their interaction with water. Previous studies suggest relationships between collagen or PGs and tissue mechanics [1,2]. However, no study to date has isolated the contributions that distinct tendon components make to the elastic and viscoelastic properties of tendon. Recently, transgenic mice with prescribed mutations or deletions of various genes for specific tendon constituents have become available. In this study, we use transgenic mice as a tool to investigate the contributions of tendon components to tendon function based on a previously described approach [3]. In particular, we compare the strain rate sensitivity among fascicles from the tails of mice described in Table 1. We hypothesize that (a) fascicles with alterations in type I collagen (C1TJ8 and C1M8) will have different elastic properties but no difference in strain rate sensitivity than age-matched controls (CTL8), and (b) fascicles with alterations in proteoglycan (DKO8 and CTL3 [4]) will have different elastic properties and different strain rate sensitivity than CTL8 fascicles.
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Thorpe, Chavaunne T., Helen L. Birch, Peter D. Clegg e Hazel R. C. Screen. "Effect of Fatigue Loading on Tendon Fascicle Extension Mechanisms". In ASME 2013 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/sbc2013-14009.
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Tendon injury is common, probably occurring due to accumulation of microdamage within the tendon matrix as a result of repetitive loading rather than as a sudden onset condition 1. The human Achilles tendon is highly susceptible to injury; this tendon functions as an energy store and experiences high stresses and strains during normal use 2. The equine superficial digital flexor (SDFT) is also an energy storing tendon and is highly injury prone, therefore it is often used as a model to study structure function relationships within this type of tendon 3. Our previous work has characterized the microstructural response of SDFT fascicles to applied strain, with results indicating the presence of a helical component to the fascicle which may facilitate extension by unwinding of the coil 4. The aim of this study was to assess the effect of cyclic fatigue loading (creep) on the microstructural strain response of the equine SDFT to test the hypothesis that fatigue loading would result in altered fascicle extension mechanisms.
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Valenti, Fabio. "The Fascial System". In Socratic Lectures 8. University of Lubljana Press, 2023. http://dx.doi.org/10.55295/psl.2023.i13.
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The word Fascia has long been used by gross anatomists to embrace a spectrum of undifferentiated mesenchymal tissues that wrap organs and tissues of the body, or form a packing material between them. The inherent implication of this traditional view is that fasciae are inconsequential residues that are less important than the tissues with which they are associated. The errors of this assumption are being exposed and undoubtedly fascia is becoming more and more of considerable importance to many professionals working in health-related disciplines. Encouragingly, there has been a strong resurgence of interest into both basic and applied research in fasciae in recent years, also thanks to new fascia related findings. Knowledge of the fascial system’s characteristics and functions is spreading from primary medical researchers to professionals in many health fields throughout the world. Nowadays is well known that the Fascia is a mechanically active tissue with a proprioceptive and nociceptive properties. The Fascial continuum complexity is the result of perfect synergy evolution among different tissues made up of solid and fluid portions, which interpenetrate and interact with each other, forming a polymorphic three-dimensional network. Normal movement of the body is allowed because of the presence of the fascial tissues and their inseparable interconnection, one of the fundamental characteristics of the fascia is the ability to adapt to mechanical stress, remodeling the cellular/tissue structure and mirroring the functional necessity of the environment where the tissue lays. So, Fascia can transmit tension and in view of its proprioceptive and nociceptive functions could be responsible for disorders and pain radiating to remote anatomical structures. Dysfunction of the fascial system that is perpetuated in everyday movements can also cause an emotional alteration of the person. So, the fascial unity could influence not only movement but also emotions. Because the importance of fascia in human movement (both motion and emotion), shock absorption, metabolic and physiological processes, proprioception, healing and repair, the fascia in a broadest sense may be the literal representation of our inner being. Theoretically, Fascia probably hold many of the keys for understanding muscle action and musculoskeletal pain, and maybe it is of pivotal importance in understanding the basis of the body functioning. Further intensive research is essential to understand the function of the Fascia. The proposed article is a reflection to better understand the anatomy and main characteristics of the human fascial system. Keywords: Fascia; Facial system; Myofascial chains
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Poudel, Biswas, e Istemi B. Ozsoy. "Finite Element Analysis of the Critical Buckling Load in Hollow Microneedles With Lateral Support". In ASME 2022 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/imece2022-94699.
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Abstract Hollow microneedles provide minimum invasion to the skin and painless drug and vaccine delivery. However, there is a risk of fracture due to insufficient mechanical strength. The strength of microneedles might be increased by mimicking the bite of a mosquito. A mosquito has a proboscis that consists of a long needle (fascicle) surrounded by a protective sheath (labium). This sheath (labium) folds back as the fascicle pierces the skin, which provides lateral support to the fascicle. The lateral support increases the force that can be applied at the tip of the needle without buckling. In this study, the effect of lateral support on the buckling strength of a hollow microneedle made of chitin is analyzed numerically by using ABAQUS Finite Element Analysis software. The needle is modeled as a slender rod subjected to non-conservative (Beck) and conservative Euler loads simultaneously at the end. For a prescribed Beck load, the critical Euler load for buckling is obtained for various lateral elastic foundation stiffnesses. It is shown that the results of this computational study agree well with the analytical solution found in the literature. In addition, a three-dimensional finite element model is considered to study the effect of the needle tip geometry on the buckling and bending behavior of the needle.
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Haslach, Henry W., Jonathan Chung e Aviva Molotsky. "Fracture Mechanisms in Bovine Aorta". In ASME 2010 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2010. http://dx.doi.org/10.1115/sbc2010-19366.
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Rupture of vascular tissue in the circulatory system under non-impact loading is involved in potentially life threatening events such as Marfan’s syndrome or rupture of small renal veins during shock wave lithotripsy. The rupture mechanisms are not well-understood. The complexity of the artery wall precludes the use of rupture theories invented for metals or for fibered composites with a homogeneous matrix. Artery tissue is composed of ground material, smooth muscle cells, elastin and collagen. The collagen fibers, which are generally circumferentially oriented, are the load carrying material after large deformations. Clark and Glagov [1] propose that the media of an elastic artery is built of musculo-elastic fascicles made up of a layer of circumferentially oriented SMC that lie parallel and between two elastin lamellae. Between the elastin sheets of adjacent elements are interspersed collagen fiber bundles.
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Han, Woojin M., Nandan L. Nerurkar, Lachlan J. Smith, Nathan T. Jacobs, Robert L. Mauck e Dawn M. Elliott. "Multi-Scale Structural and Tensile Mechanical Response of Annulus Fibrosus to Osmotic Loading". In ASME 2012 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/sbc2012-80471.
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The annulus fibrosus (AF) is a multi-lamellar fibrocartilagenous ring in the intervertebral disc. The variation of biochemical composition from the outer to the inner AF is largely responsible for the heterogeneous mechanical properties. In vitro tissue-level studies require mechanical testing in aqueous buffers to avoid tissue dehydration. The varying glycosaminoglycan (GAG) contents from outer to inner AF suggest that the response to high and low PBS osmolarity may also be different with radial position. Previous studies in tendon and ligament have been conflicting: soaking tendon fascicles in PBS decreased tensile modulus1 and treating ligament in buffer had no effect on modulus.2
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Saeidi, Nima, e Jeffrey W. Ruberti. "Smart Molecules: Organization and Morphology of the Self-Assembled Collagen Fibrils Formed From a Solution of Densly Packed Collagen Monomers". In ASME 2008 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2008. http://dx.doi.org/10.1115/sbc2008-193025.
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Load-bearing tissues owe their mechanical properties to the presence of highly-organized arrays of collagen fibrils. Aligned lamellae in cornea and aligned fascicles in tendon are the best examples of collagen fibrillar organization at the macroscopic level. The process by which collagen is organized in the extracellular matrix (ECM) is still unclear. But it is generally thought to be facilitated locally via “fibripositors” or cell surface “crypts”. According to this theory, fibroblasts create bounded “compartments” in the ECM through which they deposit organized groups of fibrils (in the form of lamellae in the cornea and in the form of fascicles in the tendon) [1, 2]. An alternative hypothesis proposed by Marie Giraud-Guille suggests that fibroblasts concentrate collagen monomers to form cholesteric liquid crystalline patterns that resemble those found in collagenous matrices in vivo [3–8]. Such organization has been demonstrated in vitro using extracted collagen monomers. However, the data presented in these studies focuses principally on the alignment of the collagen molecules and not on the organization and resulting morphology of condensed collagen fibrils. Considering that matrix mechanical properties in vivo are the result of the fibrillar alignment and not the alignment of individual molecules, further investigation of cholesterically organized condensed fibrils and their morphology is necessary.
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Marie, Hazel, Diana L. Fagan e Jeremy Heffner. "Biomechanical Evaluation of Autologous Mesenchymal Stem Cell Transplantation to Improve Fascial Repair". In ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-12466.
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Hernia repair continues to be one of the major problems faced by surgeons. Up to 10% of laparotomies are complicated by post-operative incisional hernia, carrying with it a myriad of complications ranging from cosmetic disfigurement to life-threatening strangulation of the bowel [1]. A large percentage of these incisional hernias will recur following surgical repair leading to a more vicious cycle of hernia, followed by repair, followed by hernia. It is therefore imperative to create a more optimum wound-healing environment. The intent of this study was to investigate a novel approach for significantly reducing the initial occurrence of incisional hernia and their associated morbidities, thereby halting the vicious cycle of hernia formation.
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Reese, Shawn P., e Jeffrey A. Weiss. "Micromechanical Model of a Collagen Based Tendon Surrogate: Development and Validation". In ASME 2012 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/sbc2012-80949.
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In tendons and ligaments, collagen is organized hierarchically into nanoscale fibrils, microscale fibers and mesoscale fascicles. Force transfer across scales is complex and poorly understood, and macroscale strains are not representative of the microscale strains [1]. Since innervation, the vasculature, damage mechanisms and mechanotransduction occur at the microscale, understanding such multiscale interactions is of high importance. In this study, a physical model was used in combination with a computational model to isolate and study the mechanisms of force transfer between scales. The objectives of this study were to develop a collagen based tendon surrogate for use as a physical model and subject it to tensile loading, and to create and validate a 3D micromechanical finite element (FE) model of the surrogate.
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Cheng, Xingguo, Nicholas Wasserman e Ozan Akkus. "Improving the Anisotropy of Collagen by Electric Field Increases Its Toughness by Two-Fold". In ASME 2007 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2007. http://dx.doi.org/10.1115/sbc2007-176705.
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Collagen is the major structural protein in the connective tissues such as skin, bone, ligaments, and tendons. The specific hierarchical organization of collagen molecules determines the unique properties of each specific tissue. For example, in tendon, the parallel alignment of collagen molecules, fibrils, fibril bundles, fascicles and tendon units gives tendon good mechanical properties. Thus, in vitro engineering of collagen molecules hold great promise as a tissue regeneration material. However, there is a need for mechanically superior collagenous structures, which currently cannot be provided by isotropic gels which lack defined orientation. Increasing the anisotropy of gels would increase the strength of collagenous constructs tremendously.