Faculty of Health Sciences Master of Science in Medicine 0204267n / Creatine is one of the most frequently or generally used ergogenic substances. It is used by professional and amateur athletes and the “man on the street”. Creatine is involved in energy production and protein synthesis in muscle. Although studies have been carried out on the effect of creatine on adults, no study has yet determined whether creatine would have an influence on the developing rat foetus if taken by a female during pregnancy. The aim of this study was thus to determine whether creatine had an effect on the developing foetus. Dams were divided into two groups, which we re injected between days 7-13 and on days 9 and 11 only of intra-uterine development respectively. Each group was subdivided into a control and two experimental groups. Experimental group one received a low dose of creatine (53.5mg/250g body weight); the other experimental group received a high dose of creatine (107mg/250g body weight). The control group received an equal volume (1ml) of the vehicle (saline) in which the creatine was constituted. Dams were sacrificed on day 20 of development. The foetuses were removed and their weight and length taken. Foetuses were examined for abnormalities. Two foetuses from each litter underwent skeletal staining. Tissue was excised from the remaining foetuses and processed for histology for histological investigation. Creatine positively affected the growth of the foetuses of dams injected between days 7-13, while foetuses of dams injected only on days 9 and 11 in the B-group showed reduced growth. Creatine also had a slightly negative effect on the histological structure of the liver, but enhanced skeletal muscle growth, endocrine cell formation (pancreas) and skeletal formation. From the results obtained it is hypothesized that creatine and insulin together may play a positive role from implantation to birth, while creatine given at certain stages of organogenesis delayed development of the foetus.

Faculty of Health Sciences School of Physiotherapy 9605675x lindsayharris912@hotmail.com / Coaches and athletes are continually searching for ways to gain the "competitive edge" and improve athletic performance. Ergogenic substances and procedures are used routinely at almost all competitive levels. Creatine has become one of the most popular nutritional supplements among athletes in recent times. There is evidence suggesting that there are side effects of creatine supplementation. These include renal stress/failure, muscle injury and cramping. While creatine supplementation has the potential to be a safe and effective nutritional aid, these potential side effects may lead to long term problems in athletes. The aim of the study was to determine whether creatine supplementation is associated with injury defined as cramping and muscle strains. This was done using a questionnaire. A questionnaire was developed to consist of three sections determining the player’s training program, incidence of injury and use of creatine supplementation, if any. A pilot study was conducted to establish the validity and reliability of the questionnaire, estimate the time for data collection and identify any unanticipated problems. First team rugby players between the ages of 16 and 19 selected from six competitively recognized rugby schools within the Gauteng Province were included in the study. Consent was obtained from the headmasters of the relevant schools, coaches, and parents/guardians. Questionnaires were completed with the researcher present to explain any part of the questionnaire, which the players did not understand. Data were analyzed using the odds ratio from a logistic regression. The results reveal that no association exists between creatine supplementation and muscle injury in the form of cramping and muscle strains. The subjects were not aware of creatine supplementation recommendations and as a result it was being taken inconsistently and haphazardly.

Hutchinson-Gilford Progeria Syndrome (HGPS) is a rare genetic disorder associated with premature aging in various tissues and organs of the afflicted individuals, including accelerated skeletal muscle atrophy. Classical HGPS manifests due to single-base substitution in the LAMNA gene which encodes Lamin A/C proteins. As a result of the mutation, a truncated form of Lamin (known as Progerin) is produced which undergoes persistent farnesylation during post-translational modification. Accumulation of Progerin in the nucleus has been linked to various cellular abnormalities including abnormal nuclear morphologies and altered chromatin organization, among others. However, the exact molecular mechanisms leading to skeletal muscle atrophy have not yet been elucidated. In this study, the iPSC approach was implemented in order to study the skeletal muscle phenotype of HGPS by generating and characterizing a population of Pax7 positive skeletal muscle precursor cells (SMPs). During the course of this project, we have demonstrated the need for excessive optimization of the previously developed directed differentiation protocol for successful application on induced Pluripotent Stem Cells. Furthermore, we have successfully modified the protocol to allow for a more rapid expansion of the SMPs through regular passaging of the myogenic cells starting on day 20 of differentiation. Additionally, this new method produced more uniform distribution of the myogenic cells and allowed for successful freezing/thawing of the myogenic cells. When compared to the controls, the HGPS-derived SMPs did not appear to be defective in formation, proliferation or differentiation. Abnormal nuclear morphology and DNA damage, documented in HGPS fibroblasts and vascular smooth muscle cells, were not detected the in myogenic cells. Furthermore, we were not able to detect Progerin protein accumulation in the generated myogenic cultures, offering an explanation for the absence of these phenotypes in the skeletal muscle system.

by Cai Dong Qing. / "January 2001." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2001 / Includes bibliographical references (p. 179-190). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

by Lee Yau-choi. / Title in Chinese: / Includes bibliographical references / Thesis (M.Ph.)--Chinese University of Hong Kong, 1986

Ryanodine receptors (RyRs) are intracellular homotetrameric Ca2+-release channels constituting a family of three different isoforms, named RyRl, RyR2 and RyR3. RyRl and RyR2 are highly expressed in skeletal and cardiac muscles respectively, where they localize in the terminal cisternae of the sarcoplasmic reticulum (SR). Although RyRl and RyR2 have been found to be expressed in several other tissues at much lower level than in striated muscles, their major functional role is related to Ca2+-release from the SR following electrical depolarization of the plasma membrane, a process referred to as excitation-contraction (e-c) coupling and known to regulate striated muscle contraction. The third isoform, RyR3, is characterized by a wide pattern of expression, without any specific association to a tissue or a cell-type. The finding that RyR3 is also expressed in mammalian skeletal muscles parallels the presence of two distinct isoforms, o- and P-RyR, in non-mammalian vertebrate skeletal muscles, and suggests that two functionally distinct RyRs may be involved in the regulation of skeletal muscle contraction. The expression of RyR3 was analyzed in murine skeletal muscle from late foetal stages to adult, throughout neonatal phases of development. RyR3 was expressed widely during skeletal muscle post-natal development, disappearing in all muscles analyzed except diaphragm and soleus. RyR3 knockout mice were generated, and contractile properties of skeletal muscles were analyzed. Skeletal muscle contraction in RyR3-/- mice was impaired during the neonatal phase of development. In skeletal muscles isolated from RyR3-1- mice, the twitch elicited by electrical stimulation was strongly depressed. A significant reduction of the contractile activity was also elicited after stimulation with caffeine, an activator of Ca2+-release through RyRs. In the adults, no differences were detected between wild-type and mutant mice. These results are the first demonstrations of a physiological role of RyR3 in excitation-contraction coupling mechanisms of skeletal muscle, and support the model of a two-channel system regulating skeletal muscle contraction. In order to further characterize the RyR3-1- mouse, [3H]ryanodine binding experiments were performed on diaphragm and total hindlimb skeletal muscles from RyR3+/+ and RyR3-1- mice. Preliminary results will be presented and discussed.

Le vieillissement de la population est un phénomène universel dont l'amélioration des conditions de vie est la principale cause. Cependant, dans 20% des cas, l'avancée en âge s'accompagne aussi d'une perte de l'autonomie qui nécessite une prise en charge institutionnelle lourde pour le patient et la société. Une des principales causes de cette transition fragilité/dépendance réside dans la diminution dramatique de la masse et de la fonction musculaire, aussi appelée sarcopénie. Dans ce contexte, il devient primordial de mieux caractériser cette pathologie afin de mettre au point de nouvelles stratégies thérapeutiques. Dans cette optique, nous nous sommes intéressés à l'apeline, un peptide endogène circulant, dont le rôle favorable sur le métabolisme énergétique du muscle squelettique a été mis en évidence au sein du laboratoire dans un contexte d'obésité. A partir de ces précédents résultats nous avons donc émis l'hypothèse d'un rôle bénéfique de l'apeline sur la physiologie du tissu musculaire au cours du vieillissement. Dans un premier temps, nous avons démontré que la contraction du muscle strié squelettique in vitro et in vivo chez la souris et l'homme, générait une production et une sécrétion musculaire d'apeline. Cette régulation par l'exercice physique est apparue altérée chez les souris âgées, et ceci s'accompagne d'une diminution des taux d'apeline plasmatiques chez la souris, comme chez l'individu âgé. De plus, nous avons pu démontrer, chez l'homme âgé pratiquant un exercice chronique, l'existence d'une corrélation entre les capacités d'augmentation de l'apelinémie et l'efficacité de l'exercice en termes de force physique. Parallèlement, nous avons pu mettre en évidence une augmentation significative de la masse et de la fonction musculaire de souris âgées suite à une supplémentation (pharmacologique ou génique) chronique en apeline. Ces effets s'expliquent en partie par l'activation du métabolisme énergétique des fibres musculaires, nécessitant l'activation de l'axe AMPK-PGC1a qui permet une potentialisation de la biogénèse mitochondriale. D'autre part, des expériences de régénération musculaire démontrent que l'apeline est également capable d'activer les cellules satellites, cellules souches résidentes du muscle squelettique. Au cœur de différentes approches (prédictive, préventive et thérapeutique), l'apeline s'inscrit dans un nouvel axe de recherche quant à la détection (biomarqueur) et la prise en charge (traitement pharmacologique) des faiblesses musculaires associées au vieillissement. / Population aging is universal phenomenon explained mostly by improvement of living condition. However, in 20% of cases, aging is associated with loss of autonomy needing high intensity care for both patients and society. Dramatic loss of skeletal muscle mass and function, called sarcopenia, is the main cause of transition from frailty to dependency. It becomes essential to precisely characterize this pathology in order to develop new therapeutic strategy. In this context, we focused on apelin, a circulating endogenous peptide, which has been described in our lab as energetic metabolism booster of obese mice skeletal muscle. From this previous work, we made the hypothesis that apelin could have a beneficial role on skeletal muscle physiology during aging. First, we put out, in vitro and in vivo, that mice and human muscle contraction lead to muscle apelin production and secretion. This regulation appeared blunt in aged mice, combined with decrease of plasma apelin in aged mice and elderly. Furthermore, in old patient, there is a positive correlation between rising plasma apelin ability and success of training on improvement of skeletal muscle function. Beside, pharmacologic or gene chronic apelin supplementation leads to significative gain of skeletal muscle mass and function in old mice. Explanation takes place in improvement of energetic metabolism of muscle fibers through mitochondrial biogenesis in an AMPK-PGC1a dependant pathway. In another hand, muscle regeneration experiments showed activation of satellite cells, skeletal muscle resident stem cells, by apelin supplementation. Apelin appeared to be in the crossroad of distinct approaches (predictive, preventive and therapeutic) in future research angle as biomarker and pharmacological treatment of age-induced skeletal muscle weakness.

A robust, reliable method to non-invasively measure in-vivo mechanical properties of large tissue areas was unavailable until the advent of a new Magnetic Resonance Imaging (MRI) technique known as Magnetic Resonance Elastography (MRE). MRE is a phase-contrast imaging technique that enables quantification of tissue mechanical properties by capturing the motion of induced shear waves via a synchronised Motion Encoding Gradient (MEG). The complex shear modulus is determined via mathematical inversion and reported as the magnitude of the complex shear modulus, |G*|, and phase angle, φ. The work reported in this thesis focuses on the development of MRE data acquisition and analysis protocols optimised to study thigh muscle mechanical properties. The protocols are subsequently applied in healthy volunteers to study natural phenomena such as contraction and ageing and interventions such as an experimental protocol to produce Exercise Induced Muscle Damage (EIMD). Methodological advances made throughout this work include moving from 2D to 3D MRE data acquisition protocols and the application of advanced inversion software to extract muscle viscoelastic properties from the acquired MRE data. Results obtained include observation of reduced muscle stiffness in 6 elderly subjects (>80 years old) compared to 4 young subjects in the Vastus Lateralis (32%), quadriceps muscle group (22%) and entire thigh cross-section (19%), higher resting stiffness of agonist quadriceps compared to antagonist hamstrings (18%) and an increase in quadriceps stiffness (40%) during a leg raise task in 11 healthy subjects. Variability in muscle group recruitment patterns during the contraction were also observed, with the phase angle of the Vastus Intermedius (VI) increasing significantly during contraction. The final experiment involved the recruitment of 20 healthy male subjects to perform an eccentric exercise protocol designed to induce EIMD. Subjects who displayed a Maximum Voluntary Contraction (MVC) force deficit of >10% were considered to have experienced EIMD. A further severe EIMD group were defined based on the presence of hyper-intense signal on T2 weighted imaging following the protocol. The T2 hyper-intensity was found to occur exclusively in the Rectus Femoris (RF) and VI muscle groups. Increased muscle stiffness was observed in the RF muscle in subjects who experienced moderate EIMD (6%). A greater increase in RF stiffness (48%) was observed in the severe EIMD group. The severe EIMD group also displayed significantly increased VI stiffness (14%). The experiments carried out provide several novel findings which can support the development of beneficial strategies to promote both healthy ageing and rehabilitation in athletes, and potentially contribute to improving muscle performance evaluation tests which will expand the opportunities for clinical applications of muscle MRE.

MSc, Physiotherapy, Faculty of Health Sciences, University of the Witwatersrand / The Association between Trunk Muscle Endurance and Lumbar-Pelvic Instability in Adolescent Low Back Pain Françoise Lewis Supervisors: Wendy-Anne Wood, Benita Naude. Low back pain (LBP) is a common cause of discomfort in modern society, and the prevalence of LBP in the adolescent population is high and has a predictive value for the occurrence of LBP as an adult. The aim of the study was to investigate the association between adolescent LBP and trunk muscle endurance and lumbar-pelvic instability, as well as the association between trunk muscle endurance and lumbar-pelvic instability. Sports and physical activity participation, sedentary activity participation and a family history were also investigated as they have been identified in previous studies as potential risk factors. The study was a cross sectional study of 80 adolescents in grade 8 to grade 11, aged 12 to 17 year , at three high schools in Gauteng, who agreed to participate in the study. Data was collected by means of a validated questionnaire and a physical examination. The level of significance for as sociated factors was set at 0.05. The results revealed a lifetime prevalence of 82.50%, one year prevalence of 78.80% and point prevalence of 23.80%. Adolescents with LBP have decreased endurance of the trunk extensor muscles but increased endurance of the trunk flexor muscles, which is statistically significant (p=0.044) . Lumbar-pelvic instability is not associated with adolescent LBP. Extensor trunk muscle endurance and poor lumbar pelvic stability show an association (p=0.031), with those adolescents with decreased trunk extensor muscle endurance presenting with poor lumbar-pelvic stability. A family history of LBP is significant for point prevalence of LBP (p=0.012), and one-year prevalence of LBP is marginally significant (p=0.086). Low activity level particpation was reported by a large percentage of all subjects. Sedentary activity participation is moderate in the LBP group, but the results are not statistically significant . There is a need for preventative srategies to decrease the prevalence of adolescent LBP. Increased awareness of LBP and potential risk factors needs to be addressed.

This thesis details four consecutive research investigations which were designed to examine the effect of age on the pulmonary oxygen uptake (VO2)and muscle oxygenation (mOxy) responses to exercise in well-trained cyclists. (Abridged)