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Muscle Structure (muscle + structure)
Selected AbstractsCorrelated changes in skeletal muscle connective tissue and flesh texture during starvation and re-feeding in brown trout (Salmo trutta) reared in seawaterJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 11 2004Jérôme Bugeon Abstract Quantitative and qualitative changes to muscle and collagen were analysed following starvation and re-feeding of brown trout (Salmo trutta) reared in seawater. Fish were submitted to starvation for 2 months followed by re-feeding for 1 month and compared with a control group continuously fed. Classical effects of starvation on growth and morphometrics traits were observed with only a partial recovery of these parameters after 1 month of re-feeding. Muscle composition of starved fish was significantly affected (lower dry matter content and higher post-mortem pH) compared with control fish and was partially recovered in re-fed fish compared with continuously fed fish. Muscle structure and composition were affected with thinner muscle fibre and higher connective tissue content for the starved fish but similar thickness of myosepta compared with the control group. No difference was observed after 1 month of re-feeding. Characteristics of the connective tissue were significantly affected by starvation (more high weight molecular collagen form, higher thermal stability of skin collagen). These differences remained significant after the re-feeding period. Starved fish showed also higher mechanical resistance of the raw flesh compared with the control group, but no difference in rheological measurements was observed after 1 month of re-feeding. The changes in texture and their relationships with muscle composition, muscle structure and collagen characteristics are discussed. Copyright © 2004 Society of Chemical Industry [source] Analysis of conserved residues in the ,pat-3 cytoplasmic tail reveals important functions of integrin in multiple tissuesDEVELOPMENTAL DYNAMICS, Issue 3 2010Xiaojian Xu Abstract Integrin cytoplasmic tails contain motifs that link extracellular information to cell behavior such as cell migration and contraction. To investigate the cell functions mediated by the conserved motifs, we created mutations in the Caenorhabditis elegans ,pat-3 cytoplasmic tail. The ,1D (799FK800), NPXY, tryptophan (784W), and threonine (797TT798) motifs were disrupted to identify their functions in vivo. Animals expressing integrins with disrupted NPXY motifs were viable, but displayed distal tip cell migration and ovulation defects. The conserved threonines were required for gonad migration and contraction as well as tail morphogenesis, whereas disruption of the ,1D and tryptophan motifs produced only mild defects. To abolish multiple conserved motifs, a ,1C-like variant, which results in a frameshift, was constructed. The ,pat-3(,1C) transgenic animals showed cold-sensitive larval arrests and defective muscle structure and gonad migration and contraction. Our study suggests that the conserved NPXY and TT motifs play important roles in the tissue-specific function of integrin. Developmental Dynamics 239:763,772, 2010. © 2010 Wiley-Liss, Inc. [source] The future of magnetic resonance-based techniques in neurologyEUROPEAN JOURNAL OF NEUROLOGY, Issue 1 2001European Federation of Neurological Societies Task Force Magnetic resonance techniques have become increasingly important in neurology for defining: 1,brain, spinal cord and peripheral nerve or muscle structure; 2,pathological changes in tissue structures and properties; and 3,dynamic patterns of functional activation of the brain. New applications have been driven in part by advances in hardware, particularly improvements in magnet and gradient coil design. New imaging strategies allow novel approaches to contrast with, for example, diffusion imaging, magnetization transfer imaging, perfusion imaging and functional magnetic resonance imaging. In parallel with developments in hardware and image acquisition have been new approaches to image analysis. These have allowed quantitative descriptions of the image changes to be used for a precise, non-invasive definition of pathology. With the increasing capabilities and specificity of magnetic resonance techniques it is becoming more important that the neurologist is intimately involved in both the selection of magnetic resonance studies for patients and their interpretation. There is a need for considerably improved access to magnetic resonance technology, particularly in the acute or intensive care ward and in the neurosurgical theatre. This report illustrates several key developments. The task force concludes that magnetic resonance imaging is a major clinical tool of growing significance and offers recommendations for maximizing the potential future for magnetic resonance techniques in neurology. [source] Duchenne's muscular dystrophy: animal models used to investigate pathogenesis and develop therapeutic strategiesINTERNATIONAL JOURNAL OF EXPERIMENTAL PATHOLOGY, Issue 4 2003C.A. Collins Summary., Duchenne's muscular dystrophy (DMD) is a lethal childhood disease caused by mutations of the dystrophin gene, the protein product of which, dystrophin, has a vital role in maintaining muscle structure and function. Homologues of DMD have been identified in several animals including dogs, cats, mice, fish and invertebrates. The most notable of these are the extensively studied mdx mouse, a genetic and biochemical model of the human disease, and the muscular dystrophic Golden Retriever dog, which is the nearest pathological counterpart of DMD. These models have been used to explore potential therapeutic approaches along a number of avenues including gene replacement and cell transplantation strategies. High-throughput screening of pharmacological and genetic therapies could potentially be carried out in recently available smaller models such as zebrafish and Caenorhabditis elegans. It is possible that a successful treatment will eventually be identified through the integration of studies in multiple species differentially suited to addressing particular questions. [source] Development of zebrafish (Danio rerio) pectoral fin musculatureJOURNAL OF MORPHOLOGY, Issue 2 2005D.H. Thorsen Abstract During posthatching development the fins of fishes undergo striking changes in both structure and function. In this article we examine the development of the pectoral fins from larval through adult life history stages in the zebrafish (Danio rerio), describing in detail their pectoral muscle morphology. We explore the development of muscle structure as a way to interpret the fins' role in locomotion. Genetic approaches in the zebrafish model are providing new tools for examining fin development and we take advantage of transgenic lines in which fluorescent protein is expressed in specific tissues to perform detailed three-dimensional, in vivo fin imaging. The fin musculature of larval zebrafish is organized into two thin sheets of fibers, an abductor and adductor, one on each side of an endoskeletal disk. Through the juvenile stage the number of muscle fibers increases and muscle sheets cleave into distinct muscle subdivisions as fibers orient to the developing fin skeleton. By the end of the juvenile period the pectoral girdle and fin muscles have reoriented to take on the adult organization. We find that this change in morphology is associated with a switch of fin function from activity during axial locomotion in larvae to use in swim initiation and maneuvering in adults. The examination of pectoral fins of the zebrafish highlights the yet to be explored diversity of fin structure and function in subadult developmental stages. J. Morphol. © 2005 Wiley-Liss, Inc. [source] A REVIEW OF SENSORY AND INSTRUMENTAL METHODS USED TO EVALUATE THE TEXTURE OF FISH MUSCLEJOURNAL OF TEXTURE STUDIES, Issue 3 2001GRETHE HYLDIG The texture of fish muscle is an important quality attribute that depends on several parameters, both intrinsic and extrinsic. Its evaluation by sensory means is the result of a combination of several parameters that cover every impression from when the fish first comes into contact with a surface in the mouth, until it is completely masticated. This makes texture difficult to describe and evaluate. In addition the muscle structure of fish is not homogenous, and this has important implications on texture measurements by instrumental means. Numerous instrumental and sensory methods have been used to evaluate the texture of fish and fish fillets, with varying results and there exists no universal recommended method. [source] Correlated changes in skeletal muscle connective tissue and flesh texture during starvation and re-feeding in brown trout (Salmo trutta) reared in seawaterJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 11 2004Jérôme Bugeon Abstract Quantitative and qualitative changes to muscle and collagen were analysed following starvation and re-feeding of brown trout (Salmo trutta) reared in seawater. Fish were submitted to starvation for 2 months followed by re-feeding for 1 month and compared with a control group continuously fed. Classical effects of starvation on growth and morphometrics traits were observed with only a partial recovery of these parameters after 1 month of re-feeding. Muscle composition of starved fish was significantly affected (lower dry matter content and higher post-mortem pH) compared with control fish and was partially recovered in re-fed fish compared with continuously fed fish. Muscle structure and composition were affected with thinner muscle fibre and higher connective tissue content for the starved fish but similar thickness of myosepta compared with the control group. No difference was observed after 1 month of re-feeding. Characteristics of the connective tissue were significantly affected by starvation (more high weight molecular collagen form, higher thermal stability of skin collagen). These differences remained significant after the re-feeding period. Starved fish showed also higher mechanical resistance of the raw flesh compared with the control group, but no difference in rheological measurements was observed after 1 month of re-feeding. The changes in texture and their relationships with muscle composition, muscle structure and collagen characteristics are discussed. Copyright © 2004 Society of Chemical Industry [source] Kell and XK immunohistochemistry in McLeod myopathyMUSCLE AND NERVE, Issue 10 2001Hans H. Jung MD Abstract The McLeod syndrome is an X-linked neuroacanthocytosis manifesting with myopathy and progressive chorea. It is caused by mutations of the XK gene encoding the XK protein, a putative membrane transport protein of yet unknown function. In erythroid tissues, XK forms a functional complex with the Kell glycoprotein. Here, we present an immunohistochemical study in skeletal muscle of normal controls and a McLeod patient with a XK gene point mutation (C977T) using affinity-purified antibodies against XK and Kell proteins. Histological examination of the affected muscle revealed the typical pattern of McLeod myopathy including type 2 fiber atrophy. In control muscles, Kell immunohistochemistry stained sarcoplasmic membranes. XK immunohistochemistry resulted in a type 2 fiber-specific intracellular staining that was most probably confined to the sarcoplasmic reticulum. In contrast, there was only a weak background signal without a specific staining pattern for XK and Kell in the McLeod muscle. Our results demonstrate that the lack of physiological XK expression correlates to the type 2 fiber atrophy in McLeod myopathy, and suggest that the XK protein represents a crucial factor for the maintenance of normal muscle structure and function. © 2001 John Wiley & Sons, Inc. Muscle Nerve 24: 1346,1351, 2001 [source] Regulation of STARS and its downstream targets suggest a novel pathway involved in human skeletal muscle hypertrophy and atrophyTHE JOURNAL OF PHYSIOLOGY, Issue 8 2009Séverine Lamon Skeletal muscle atrophy is a severe consequence of ageing, neurological disorders and chronic disease. Identifying the intracellular signalling pathways controlling changes in skeletal muscle size and function is vital for the future development of potential therapeutic interventions. Striated activator of Rho signalling (STARS), an actin-binding protein, has been implicated in rodent cardiac hypertrophy; however its role in human skeletal muscle has not been determined. This study aimed to establish if STARS, as well as its downstream signalling targets, RhoA, myocardin-related transcription factors A and B (MRTF-A/B) and serum response factor (SRF), were increased and decreased respectively, in human quadriceps muscle biopsies taken after 8 weeks of both hypertrophy-stimulating resistance training and atrophy-stimulating de-training. The mRNA levels of the SRF target genes involved in muscle structure, function and growth, such as ,-actin, myosin heavy chain IIa (MHCIIa) and insulin-like growth factor-1 (IGF-1), were also measured. Following resistance training, STARS, MRTF-A, MRTF-B, SRF, ,-actin, MHCIIa and IGF-1 mRNA, as well as RhoA and nuclear SRF protein levels were all significantly increased by between 1.25- and 3.6-fold. Following the de-training period all measured targets, except for RhoA, which remained elevated, returned to base-line. Our results show that the STARS signalling pathway is responsive to changes in skeletal muscle loading and appears to play a role in both human skeletal muscle hypertrophy and atrophy. [source] Novel role for ,-adrenergic signalling in skeletal muscle growth, development and regenerationCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 3 2010James G Ryall Summary 1. In adult mammals, skeletal muscle mass is maintained through a precise balance of protein synthesis and protein degradation, whereas during development cellular (not protein) turnover predominates. When protein balance is shifted towards synthesis, skeletal muscle hypertrophy ensues. In contrast, increased protein degradation leads to skeletal muscle atrophy. Insulin-like growth factor (IGF)-I is among the best documented of the growth factors and regulates skeletal muscle mass by increasing protein synthesis and decreasing protein degradation. However, an IGF-I-independent growth pathway has been identified that involves the activation of ,-adrenoceptors and subsequent skeletal muscle growth, development and hypertrophy. 2. Although the importance of ,-adrenergic signalling in the heart has been well documented and continues to receive significant attention, it is only more recently that we have started to appreciate the importance of this signalling pathway in skeletal muscle structure and function. Studies have identified an important role for ,-adrenoceptors in myogenesis and work from our laboratory has identified a novel role for ,-adrenoceptors in regulating skeletal muscle regeneration after myotoxic injury. In addition, new data suggest that ,-adrenoceptors are markedly upregulated during differentiation of C2C12 cells. 3. It is now clear that ,-adrenoceptors play an important role in regulating skeletal muscle structure and function. Importantly, a clearer understanding of the pathways regulating skeletal muscle mass may lead to the identification of novel therapeutic targets for the treatment of muscle wasting disorders, including sarcopenia, cancer cachexia and the muscular dystrophies. [source] Performance-driven muscle-based facial animationCOMPUTER ANIMATION AND VIRTUAL WORLDS (PREV: JNL OF VISUALISATION & COMPUTER ANIMATION), Issue 2 2001Byoungwon Choe Abstract We describe a system to synthesize facial expressions by editing captured performances. For this purpose, we use the actuation of expression muscles to control facial expressions. We note that there have been numerous algorithms already developed for editing gross body motion. While the joint angle has direct effect on the configuration of the gross body, the muscle actuation has to go through a complicated mechanism to produce facial expressions. Therefore,we devote a significant part of this paper to establishing the relationship between muscle actuation and facial surface deformation. We model the skin surface using the finite element method to simulate the deformation caused by expression muscles. Then, we implement the inverse relationship, muscle actuation parameter estimation, to find the muscle actuation values from the trajectories of the markers on the performer's face. Once the forward and inverse relationships are established, retargeting or editing a performance becomes an easy job. We apply the original performance data to different facial models with equivalent muscle structures, to produce similar expressions. We also produce novel expressions by deforming the original data curves of muscle actuation to satisfy the key-frame constraints imposed by animators.Copyright © 2001 John Wiley & Sons, Ltd. [source] Reentry in a Morphologically Realistic Atrial ModelJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 9 2001EDWARD J. VIGMOND Ph.D. Reentry in Morphologically Realistic Atria.Introduction: Atrial fibrillation is the most common cardiac arrhythmia. In ablation procedures, identification of the reentrant pathways is vital. This has proven difficult because of the complex morphology of the atria. The purpose of this study was to ascertain the role of specific anatomic structures on reentry induction and maintenance. Method and Results: A computationally efficient, morphologically realistic, computer model of the atria was developed that incorporates its major structural features, including discrete electrical connections between the right and left atria, physiologic fiber orientation in three dimensions, muscle structures representing the crista terminalis (CT) and pectinate muscles, and openings for the veins and AV valves. Reentries were induced near the venous openings in the left and right atria, the mouth of the coronary sinus, and the free wall of the right atrium. The roles of certain muscular structures were ascertained by selectively removing the structures and observing how the propagation of activity was affected. Conclusion: (1) The muscular sheath of the coronary sinus acts as a pathway for a reentrant circuit and stabilizes any circuits that utilize the isthmus near the inferior vena cava. (2) Poor trans-CT coupling serves to stabilize flutter circuits. (3) Wall thickness is an important factor in the propagation of electrical activity, especially in the left atrium. (4) The openings of the inferior and superior venae cavae form natural anatomic anchors that make reentry easier to initiate by allowing for smaller ectopic beats to induce reentry. [source] Bone Marrow-Derived Cells Implanted into Freeze-Injured Urinary Bladders Reconstruct Functional Smooth Muscle LayersLUTS, Issue 1 2010Tetsuya IMAMURA Regenerative medicine offers great hope for lower urinary tract dysfunctions due to irreversibly damaged urinary bladders and urethras. Our aim is the utilization of bone marrow-derived cells to reconstruct smooth muscle layers for the treatments of irreversibly damaged lower urinary tracts. In our mouse model system for urinary bladder regeneration, the majority of smooth muscle layers in about one-third of the bladder are destroyed by brief freezing. Three days after wounding, we implant cultured cells derived from bone marrow. The implanted bone marrow-derived cells survive and differentiate into layered smooth muscle structures that remediate urinary dysfunction. However, bone marrow-derived cells implanted into the intact normal urinary bladders do not exhibit these behaviors. The presence of large pores in the walls of the freeze-injured urinary bladders is likely to be helpful for a high rate of survival of the implanted cells. The pores could also serve as scaffolding for the reconstruction of tissue structures. The surviving host cells upregulate several growth factor mRNAs that, if translated, can promote differentiation of smooth muscle and other cell types. We conclude that the multipotency of the bone marrow-derived cells and the provision of scaffolding and suitable growth factors by the microenvironment enable successful tissue engineering in our model system for urinary bladder regeneration. In this review, we suggest that the development of regenerative medicine needs not only a greater understanding of the requirements for undifferentiated cell proliferation and targeted differentiation, but also further knowledge of each unique microenvironment within recipient tissues. [source] Endothelin-A-receptor antagonist LU 302146 inhibits electrostimulation-induced bladder contractions in vivoNEUROUROLOGY AND URODYNAMICS, Issue 5 2006J.R. Scheepe Abstract Objectives Endothelin (ET) is a strong constrictor of smooth muscle structures. The relevance of Endothelin-A receptors in the bladder was demonstrated in several in vitro studies. The aim of this functional study was to evaluate the acute effect of the selective ET-A-antagonist LU 302146 (LU) on neurostimulation-induced bladder contractions in vivo. Methods Eight male mini pigs were anesthesized. The bladder was exposed and a double lumen catheter was inserted to perform intravesical pressure (pves) measurements. Laminectomy was performed for sacral anterior root stimulation (SARS) of S2. Four animals received the selective ET-A-antagonist LU, three atropine and one animal was treated with vehicle. Pves was recorded before and after drug administration as well as before and during neurostimulation. At the end of each LU trial, a supplementary application of 4 mg atropine was administered followed by a final SARS. Results In all experiments reproducible pves values were elicited during electrostimulation before administration of the test substance. The selective ET-A-antagonist reduced stimulation-induced bladder contraction by a mean of 57%. Additional administration of atropine inhibited the detrusor contraction almost completely during SARS. The vehicle had no effect on bladder contraction. Conclusions In the presented animal model, ET-1 inhibition with the selective ET receptor-A-antagonist LU 302146 decreases stimulation-induced bladder contraction in vivo. The results suggest that the selective ET-A antagonist LU acts on the atropine-resistant component of efferent detrusor activation since additional administration of atropine almost completely abolish detrusor contraction. This observation in addition to the involvement of ET-1 in bladder smooth muscle proliferation, raises the possibility that ET-receptor antagonists might be beneficial in patients with neurogenic bladder dysfunction or in patients with functional or anatomical BOO. Neurourol. Urodynam. © 2006 Wiley-Liss, Inc. [source] Isometric force development in human horizontal eye muscles and pulleys during saccadic eye movementsACTA OPHTHALMOLOGICA, Issue 8 2009Gunnar Lennerstrand Abstract. Purpose:, The connective tissue elements forming the check ligaments and portals of the human eye muscles have recently been ascribed with a pulley function. Active positioning of the pulleys over orbital layer contraction during eye movements has been suggested. Other studies have instead demonstrated fibrous tissue connections between all parts of the muscle and the pulleys. We aimed to compare the isometric force developed at the muscle tendon and at the pulleys of the horizontal eye muscles, and to investigate which eye muscle structures might exert force on the pulleys. Methods:, Isometric force development was recorded from the lateral and medial rectus muscles in six patients operated for strabismus under topical anaesthesia. Two strain gauge probes were used, each attached with 5,0 silk sutures either to the muscle tendon or to the pulley. The eye muscles were activated by horizontal saccadic eye movements in steps from 30 degrees in the off-direction to 30 degrees in the on-direction of the muscles. Results:, The forces developed at the tendon and pulley were almost identical with respect to amplitude and other parameters. No differences were found in forces developed at the pulleys of the medial and lateral rectus muscles. Conclusions:, The results support the presence of fibrous tissue connections between all eye muscle fibres and pulley structures, rather than orbital fibre control of the pulley. [source] | ||||||||||||||||