The aim of this project was to determine the role of contraction in skeletal muscle development. The role of the initial spontaneous contractions observed in zebrafish embryos from 17 to 24 hours post fertilisation was examined. Genetic and pharmacologic approaches were used to study paralysis-induced disruption of skeletal muscle structure and function and subsequently determine the role of contraction. The structural and functional characteristics of developing skeletal muscles were found to be regulated by a dual mechanism of both movement-dependent and independent processes, in vivo. Novel data demonstrates that contraction controls sarcomere remodelling, namely regulation of actin length, via movement driven localisation of the actin capping protein, Tropmodulin1. Myofibril length was also shown to be linked to the mechanical passive property, stretch, with lengthening leading to an increase of the muscle’s ability to stretch. In addition, myofibril bundling and the myofilament lattice spacing, responsible for active tension generation via cross-bridge formation, were shown to be unaffected by paralysis and thus, movement-independent processes. Furthermore, the mechanism of the contraction-driven myofibril organisation pathway at the focal adhesion complexes (FAC), was shown to be different in zebrafish compared to mammals, with mechanosensing revolving around the Src protein rather than Fak. In summary, the role of contraction was established as a critical driver of myofibril organisation and passive tension in the developing zebrafish skeletal muscle. Passive tension regulates muscle function by determining its operational range ensuring that the needs of locomotion are met. Furthermore, investigation of FAC’s role in the contractiondriven myofibril organisation pathway led to the discovery of a novel function for Src in zebrafish somitogenesis. These two findings (i) that contraction is a driver of myofibril organisation and (ii) that Src is a key protein of the skeletal muscle development provides the potential for new therapeutic approaches in humans.

Flying fish has specialized pectoral fins. When they are activated, they will rush out of the water, expand their pectoral fins and flap their caudal fin to glide. The pectoral fins are controlled by two groups of muscles in which the external appearance is pink. No histological investigations have been made on their muscles to verify whether they are red muscles. The purposes of this study were to compare the pectoral fin muscle, trunk white muscle and trunk red muscle by histological and proteome methods so as to understand if the pectoral fin muscles is red muscles and to infer their function. Cyselurus poecilopteins was used for this study, Result show that the sizes for the cross section of the pectoral-fin-muscle-fibers were between the white and red muscles, and a large amount of connective tissue and fat tissues are present in the space among the muscle cells. It is interpreted the pectoral fin muscles of flying fish might not belong to white muscle and red muscle, and they probably utilize lipid metabolism to provide enough energy for the gliding activates. The proteomic pages for the three muscle types were compared and differences were found in the muscle proteins: actin, myosin regulatory light chain, myosin light polypeptide; enzymes: isocitrate dehydrogenase, malate synthase, queuosine biosynthesis protein¡Fstress proteins: heat shock protein (HSP70 and HSP60). Expressions of these proteins were high in the pectoral-fin muscles than in the white and red muscles. These results suggest that the flying fish¡¦ pectoral-fin muscles may involve in the oxidative and glycolysis pathways, and the muscle fibers type maybe belong to an intermediate type of muscle fiber.

Die arterielle Hypertonie stellt heute weltweit eine der häufigsten kardiovaskulären Risikofak-toren dar. Durch ungesunde Lebensweise vor allem in der westlichen Gesellschaft ist eine stetig wachsende Prävalenz zu verzeichnen. Die vorliegende Arbeit untersucht den Einfluss arterieller Hypertonie auf das Diaphragma und den Musculus Soleus. Dabei wurden insbesondere die Funktionalität sowie molekulare und histologische Veränderungen beider Skelettmuskeln betrachtet. In einem weiteren Schritt wurde der mögliche sekundärpräventive Effekt körperlichen Trainings auf diese analysiert. Der Bluthochdruck wurde anhand eines Mausmodells durch unilaterale Neph¬rektomie, über vier Wochen subkutane Doca-Pellet Implantation (0,7 mg/d) im Nackenbereich, sowie das Zuführen von natriumchloridhaltigem Trinkwasser (1,05 %) induziert. Anschließend folgte ein zweiwöchiges Hochintensiv-Intervall-Training für die Hypertonie- plus Trainingsgruppe (HIIT+ Doca). Diese wurden mit einer Kontrollgruppe (Sham) und einer reinen Hypertonie-Gruppe (Doca) verglichen. Unter Wirkung der arteriellen Hypertonie konnte für die Doca-Gruppe im Diaphragma eine signifikante Verschlechterung der Funktionalität beobachtet werden. Im Musculus Soleus waren keine Einschränkungen dieser zu finden. Durch das körperliche Training der Tiere kam es zu einer deutlichen Verbesserung der diaphragmalen Funktionalität, welche mit den erho-benen Ergebnissen auf molekularer Ebene korrelierte. Es zeigte sich in der Doca-Gruppe eine signifikante Abnahme der kontraktilen Proteine Myosin-Heavy-Chain sowie Aktin. Diese wiederum wiesen in der HIIT-Gruppe signifikante Zunahmen auf. Auch konnte eine verstärk-te NADPH-Oxidase-Aktivität, welche als ROS-Bildner fungiert, in der Doca-Gruppe eruiert werden. Eine deutliche Minderung dieser konnte unter körperlichem Training festgestellt werden. Das anti-oxidativ wirkende Enzym SOD zeigte eine signifikante Aktivitätszunahme in der HIIT-Gruppe. Auch konnte aufgrund der verstärkten Carbonylierung der Myosin-Heavy-Chain in der Doca- Gruppe auf deutlich negative Auswirkungen innerhalb des Dia-phragmas durch arterielle Hypertonie geschlossen werden. Zudem konnten durch die erhöhte MMP-2-Aktivität im Diaphragma extrazelluläre Umbauprozesse während des HII-Trainings angenommen werden. Im Musculs Soleus fanden keine molekularen Veränderungen statt. Ebenso wenig stellten sich in den drei Gruppen histologische Veränderungen im Sinne einer Atrophie oder Fasershifts für beide Muskeln dar. Aus den hier aufgeführten Ergebnissen kann deutlich ein sekundärpräventiver Effekt unter Hochintensiv-Intervall-Training im Hypertonie-Mausmodell erkannt werden. Dabei scheint Bluthochdruck eher auf die zentrale Skelettmuskulatur in Form des Diaphragmas zu wirken. Arterielle Hypertonie gilt als eine der häufigsten Ursachen für die Entwicklung der Herzinsuf-fizienz. Oft erfahren Patienten dabei Symptome wie Dyspnoe und Belastungsintoleranz. Die vorliegende Arbeit untersucht als erste auf Ebene der arteriellen Hypertonie mögliche frühe pathophysiologische Mechanismen und deren Wirken auf die Skelettmuskulatur. Somit trägt sie erheblich zum besseren klinischen Verständnis bei.

In spite of its post mitotic nature, skeletal muscle maintains remarkable plasticity. Muscle fibres (myofibres) are capable of large alterations in their size as well as an enormous ability to regenerate following injury – thanks to a potent population of resident stem cells (satellite cells). Deciphering the molecular signalling networks responsible for skeletal muscle growth and regeneration is of key scientific interest – not least because of the therapeutic potential these pathways may hold for the treatment of diseases such as muscular dystrophy. In this thesis, the transcriptional co-factor Yes-Associated protein (Yap), the downstream effector of the Hippo Pathway, was investigated in skeletal muscle. Using gain and loss of function approaches within in vitro, ex vivo and in vivo models, the contribution of Yap in regulating both satellite cell behaviour and myofibre growth was investigated. Yap expression and activity are dynamically regulated during satellite cell activation, proliferation and differentiation ex vivo. Overexpression of Yap increased satellite cell proliferation and maintained cells in a ‘naive’, ‘activated’ state by inhibiting myogenic commitment. Knock-down of Yap impaired satellite cell expansion, but did not influence myogenic differentiation. Yap interacts with Tead transcription factors in myoblasts to upregulate genes such as CyclinD1 and Myf5. Forced expression of Yap eventually led to the oncogenic transformation of myoblasts in vitro. Contrary to predictions, constitutive expression of Yap under an inducible muscle-specific promoter in adult mice failed to induce growth and instead led to muscle wasting, atrophy and degeneration – providing evidence against the notion that Yap represents a universal regulator of tissue growth. These data provide the first insight into the function of Yap in skeletal muscle. Results highlight a novel role for Yap in regulating myogenic progression in satellite cells, as well as its propensity to induce oncogenic transformation. The precise function of Yap in adult myofibres remains unclear however, data presented here demonstrates clear cell-type specific roles for Yap compared to observations made in other tissues.

The aim of this study is to examine the effect of heat and cold on the characteristics of skeleton muscles. 24 persons of different age and attitude to sport, men and women, have been examined (12 - using passive heating, 12 - using passive cooling). The rates of vertical jumps were registered (force, power, speed, height of jumps). The rates have been registered before and after cooling and heating procedures. Jumps with and without springing squats with angles of 90 and 135 degrees have been made. After the parameters were recorded, leg mucles were heated in 44 degrees water for 45 minutes or cooled two times in 15 degrees water for 15 minutes with 10 minutes break. Obtained results showed, that the contractile features of sceleton muscles after heating changed differently, the significant improvement of power of muscles was observed, the force of the contraction was stable. After reducing temperature the features of skeletal muscles (force, power, speed) have notably deteriorated. Slow muscle fibres showed greater response to the heating. The increment of power has been noticed. Faster and slower muscle fibres reacted equally to the cooling contraction speed and power have greatly reduced. The usage of elastic energy have not changed either at lower or higher temperatures. When applying physiotherapy means, such as heating or cooling, one has to take into account the dependence of contractile properties of the muscle on the temperature.

Tyrimo tikslas – nustatyti skirtingos lyties asmenų vegetacinių sistemų funkcijos rodiklių kaitos ypatumus pastovaus intensyvumo krūvio metu po ekscentrinio-koncentrinio prieškrūvio. Tyrimo uždaviniai: 1. Nustatyti ekscentrinio-koncentrinio prieškrūvio poveikį vegetacinių sistemų rodiklių kaitai atliekant vidutinio ir didelio intensyvumo aerobinį darbą. 2. Palyginti ekscentrinio-koncentrinio prieškrūvio poveikį vegetacinių sistemų rodiklių kaitai ir sukelto vėluojančio skausmo raumenyse poveikį atliekant įvairaus intensyvumo aerobinį darbą tarp skirtingos lyties asmenų. Tyrimo metodai ir organizavimas.Tyrimuose sutiko dalyvauti 18-ka tiriamųjų, merginos (n=10), kurių amžius buvo 20,9 (0,5) m. ir vaikinai (n=8), jų amžius – 20,8 (1,9) m. Siekiant nustatyti aerobinį pajėgumą tiriamieji po veloergometru „Ergoline –800“ (Vokietija) atliko nepertraukiamą nuosekliai kas 5 s didinamą krūv�� (NDK). Mynimo dažnumas buvo 70 k./min. Pirmas 3 minutes krūvis buvo 20 W, toliau krūvis buvo didinamas po 2 W iki nuovargio, t.y. tol, kol tiriamasis galėjo išlaikyti pastovų mynimo dažnumą. Pagal deguonies suvartojimo per paskutines krūvio 15 s priklausomybę nuo darbo galingumo buvo nustatomas maksimalus deguonies suvartojimas ( max). Pirmas ir antras ventiliaciniai slenksčiai (VeS1, VeS2) buvo nustatomi pagal Ve, o taip pat Ve/ ir Ve/VCO2 ekvivalentų priklausomybę nuo darbo galingumo. Po nepertraukiamo nuosekliai didinamo krūvio tiriamieji atliko individualizuotą vidutinio intensyvumo aerobinį... [toliau žr. visą tekstą] / The aim of this study was to ascertain the sex differences in the influence of prior eccentric-concentric load on the kinetics of cardiorespiratory parameters during constant intensity exercise. The tasks set were as follows: 1. To estimate the influence of prior eccentric-concentric load on the changes of cardiorespiratory parameters during moderate and high intensity exercises. 2. To compare sex differences in the influence of prior eccentric-concentric load on the changes of cardiorespiratory parameters and effect of delayed onset muscle soreness during various intensity exercises. Materials and methods. The subjects were ten healthy female 20,9 (0,5) years and eight healthy male 20,8 (1,9) years volunteered to participate in this study. The first test was used to measure their maximal oxygen uptake during an incremental exercise (3 min was 20 W and then 2 W/ 5s at 70 rev/min) to exhaustion on the cycle ergometer Ergoline-800 (Germany). Depending of in last 15 s on load output was determinate max. Both first and second ventilatory thresholds (VeS1, VeS2) were determinate by pulmonary ventilation (Ve) and depending of Ve/ and Ve/VCO2 equivalents on load output. Thereafter, the moderate intensity exercise (MI) corresponding to 80% of VeS1, and high intensity exercise (HI) corresponding to 50% of VeS2 and VeS1 inequality was determined individualized load for each subject. Cycling rapid was 70 rev./min. During whole tests of each respiratory period were recorded indices as... [to full text]

No description available.

Thesis (MSc (Physiological Sciences)--University of Stellenbosch, 2009. / ENGLISH ABSTRACT: Although muscle tissue demonstrates a remarkable capacity for regeneration following injury, this process is slow and often accompanied by the formation of scar tissue and a subsequent decrease in contractile capacity following regeneration. Treatment options are few and mostly supportive in nature. This regeneration process involves muscle stem cells (satellite cells) which ultimately give rise to the regenerated muscle. The contentious field of low level laser therapy (LLLT) has made remarkable claims in facilitating wound healing in soft tissue injuries of various types. Yet, the mechanism(s) invoked in these beneficial effects are poorly understood. We have investigated the effects of LLLT using a 638 nm laser on satellite cells in culture and in-vivo. Using an array of techniques we have measured, amongst other things, metabolic responses to laser irradiation, signaling pathways activated/altered and antioxidant status. In response to laser irradiation satellite cells in culture showed an increase in MTT values (a measure of metabolic activity) and a decrease in antioxidant status (measured using the ORAC assay). In addition laser irradiation also altered the expression and phosphorylation state of several signaling pathways, including Akt and STAT-3. Following on from this the effects of laser irradiation on satellite cells in-vivo was assessed in a rat model of contusion injury. No significant differences in satellite cell number was found following laser irradiation, changes were seen in tissue antioxidant status and blood antioxidant status (measured using the ORAC assay). In the course of this study several standard techniques were used to investigate the effects of laser irradiation on satellite cells both in-vitro and invivo. It has become apparent that several of these techniques have problems associated with them that possibly make them inappropriate for vi further use in studies involving laser irradiation. However the results indicate that laser therapy is induces satellite cell behavior and further study is warranted in this field. / AFRIKAANSE OPSOMMING: Alhoewel spierweefsel merkwaardige regenerasie kapasiteit vertoon ten opsigte van besering, is hierdie proses stadig en word soms vergesel met die vorming van letselweefsel asook ‘n gevolglike afname in kontaktiele kapasiteit na afloop van regenerasie. Behandelingsmoontlikhede is skaars en meesal ondersteunend van aard. Hierdie proses sluit spierstamselle (satelietselle), wat uiteindelik die ontstaan van die regenerasie van spier tot gevolg het, in. Die kontroversiële veld van lae vlak laserterapie (Engels: Low level laser therapy (LLLT)) het merkwaardige aansprake in die fasilitering met verskeie sagteweefsel wondgenesing. Nietemin, die meganisme(s) wat voordelige effekte induseer, word nog nie goed begryp nie. Ons het die effek van LLLT, deur gebruik te maak van ‘n 638 nm laser op kultuur in vitro satelietselle sowel in-vivo, ondersoek. Deur gebruik te maak van verskeie tegnieke is onder meer die metaboliese, sowel die seinstransduksie weë en antioksidantstatus na laserbestraling, gemeet. In reaksie op die laserbestraling het satelietselle (in kultuur) ‘n toename in MTT waardes getoon (‘n maatstaf van die metaboliese aktiwiteit) en ‘n afname in die antioksidantstatus (gemeet deur van die ORAC toets). Addisioneel het laserbestraling ook uitdrukking en fosforilering van verskeie proteïene betrokke in seintransduksieweë beïnvloed, insluitend Akt, STAT-3). Na afloop van hierdie effekte op satelietselle na laserbestraling, is daar gebruik gemaak van ‘n kneusbeseringsrotmodel om hierdie effekte in vivo te ondersoek. Geen betekenisvolle verskille in die aantal satelietselle na laserbestraling is opgemerk nie, maar veranderings is wel opgemerk in weefsel- en bloed-antioksidantstatus (gemeet deur van die ORAC toets gebruik te maak). Gedurende die verloop van die studie is van verskeie standaardtegnieke gebruik gemaak om die effekte van laserbestraling op beide satelietselle in vitro en in vivo te ondersoek. iv Dit het duidelik na vore gekom dat daar wel gepaardgaande probleme met van hierdie tegnieke voorgekom het, en dat van hierdie tegnieke nie gepas is vir ondersoek in laserbestralingsstudies nie. Nietemin, die resultate toon wel dat laserbehandeling. satelietselgedrag induseer wat verdere studie in hierdie veld noodsaak

No description available.

La myostatine est un membre de la superfamille du TGF-β (transforming growth factor-β) impliqué dans la régulation négative de la masse musculaire. En effet, l’absence de myostatine (MSTN) chez la souris est responsable d’un phénotype hypermusclé. Depuis, il a été confirmé qu’une baisse de l’activité de la MSTN conduit à une augmentation de la masse musculaire chez d’autres espèces, y compris l’Homme. L’identification de la MSTN et des conséquences de son invalidation sur le développement musculaire ouvre de nombreuses perspectives en médecine humaine. Il existe de nombreuses situations pathologiques qui conduisent à une fonte musculaire importante : c’est le cas pour des maladies génétiques telles que les dystrophies musculaires ou pour d’autres pathologies comme le cancer et le sida. Différentes approches anti-MSTN ont été développées au cours des dernières années, par exemple un anticorps anti-MSTN ou des ligands de la MSTN. L’objectif majeur de ce projet de recherche a consisté à identifier de nouveaux inhibiteurs de la MSTN, en particulier appartenant à la famille de protéines appelées SLRP (Small Leucine Rich Proteoglycans). Il a été mis en évidence que des membres de cette famille, notamment la décorine (DCN) ainsi que des fragments issus de la DCN dont le peptide 31-71, sont capables de se lier à la MSTN en présence de zinc. La DCN peut alors empêcher l’activité de la MSTN en s’opposant à la liaison de cette dernière à son récepteur. Dans ce contexte, nous avons étudié des séquences peptidiques plus restreintes de la DCN murine pouvant interagir efficacement avec la MSTN et des peptides dérivés d’autres SLRP pour leur aptitude à lier la MSTN. Afin de faciliter le criblage in vitro de ces composés, nous avons tout d’abord créé une lignée cellulaire HEK293T exprimant stablement une cassette inductible par la MSTN fusionnée au gène de la luciférase (pCAGA-Luc). Parmi les candidats testés, le peptide mDCN48-71 a été le plus intéressant de par sa forte activité anti MSTN in vitro comparée aux autres, avec un IC50 de 7 µM. Notons également que le peptide mDCN48-71 n’a pas inhibé d’autres membres de la superfamille du TGF-β : TGF-β2, activine A et GDF-11 – ce qui suggère une spécificité d’action du peptide. En outre, des études d’anisotropie de fluorescence ont permis de prouver l’interaction directe du peptide mDCN48 71 avec la MSTN et la dépendance au zinc de cette liaison. Pour finir, nous avons montré que des injections intramusculaires répétées de ce peptide chez le modèle murin dystrophique mdx, conduisent à une augmentation significative de la masse des muscles tibiaux antérieurs injectés de l’ordre de 21 % par rapport aux muscles contrôles. / Myostatin is a member of the transforming growth factor-β (TGF-β) superfamily and a negative regulator of skeletal muscle growth. In 1997, lack of myostatin (MSTN) was related to increased muscle mass in mice. Since then, MSTN has been found in other species including humans. Inhibition of this protein offers opportunities in human medicine for many pathological conditions leading to a significant muscle loss: genetic disorders such as muscular dystrophy as well as other diseases like cancer and AIDS. Recently, several anti-MSTN approaches have been developed such as antibodies against MSTN or naturally occurring proteins that bind to and inactivate MSTN. The aim of this research was to identify novel inhibitors of MSTN, especially belonging to the SLRP (Small Leucine Rich Proteoglycans) family of proteins. Members of this family, including decorin (DCN) and fragments thereof (murine derived peptide mDCN31-71) can bind to MSTN in a zinc-dependent manner. In this context, smaller peptide sequences of mouse DCN and peptides from other SLRP have been studied for their ability to bind MSTN. First, we created a HEK293T stable cell line expressing the luciferase gene under control of a MSTN-inducible promoter (pCAGA-Luc) so as to screen these compounds in vitro. Here we report that the peptide mDCN48-71 shows the stronger activity anti MSTN in vitro among all the peptides tested (IC50 = 7 µM). Furthermore, other members of the TGF β superfamily: TGF β2, activin A and GDF-11 are not inhibited by the mDCN48-71 peptide - which suggests a specificity of its action. By performing fluorescence anisotropy studies, we proved the direct and zinc dependent interaction between peptide mDCN48-71 and MSTN. Finally, we showed that repeated intramuscular injections of this peptide in the dystrophic mdx mouse model led to a significant increase of the injected tibialis anterior muscle mass (21 %) compared to control muscles.