Dissertation submitted in compliance with the requirements for the Masters Degree in Chiropractic at the Durban University of Technology, 2009 / Occupational injuries sustained by Emergency Rescue Care workers have been well documented. However, despite their high rates of injury, the literature regarding the risk factors for work-related musculoskeletal injuries (WRMSIs) in the fire service has not been well-established, especially in South Africa. Objectives: To determine the prevalence and risk factors for musculoskeletal injuries in the Durban Metropolitan Fire Department and to evaluate the relationship between selected risk factors and the prevalence of musculoskeletal injuries. Methods: This was a descriptive study from a large urban Fire Department employing 350 active firefighters. Using a cross sectional study design, a retrospective analysis investigated the musculoskeletal injury prevalence from 2006-2008 by means of a questionnaire. Individuals reported on demographics, injury location, injury etiology, injury nature, extent of treatment rendered and time lost from work. Additionally, data was obtained regarding smoking, occupational stress, fitness, protective gear and injury prevention advice given by the Durban Metropolitan Fire Department. A 41% response rate was achieved. Results: The point prevalence of WRMSIs was 33.6% and the period prevalence was 81.1% of the sample. Low back injuries (47.9%) and strain injuries (40.8%) were the most common, followed by knee (22.5%), shoulder (19.7%) and ankle injuries (19%). The most common causes included lifting heavy objects, working in awkward postures and running. Weight, ethnic group, stress, lack of nutritional advice and alcohol consumption were all significantly associated with the prevalence of injuries. Ex-smoking was significant in the prevalence of low back injuries, stress was significant in the prevalence of knee injuries and alcohol consumption was associated with the prevalence of shoulder injuries. Conclusion: WRMSIs are of great concern in the fire service as their prevalence is substantial. Evaluation and implementation of further preventative measures and advice based on the results of this study can be effective in reducing WRMSIs.

Dissertation submitted in partial compliance with the requirements for the Master’s Degree in Technology: Chiropractic, Durban University of Technology, 2010. / Background: Professional orchestral string musicians are exposed to many physical and psychological stressors due to demands placed on them from playing their instruments. The prevalence of performance-related musculoskeletal disorders (PRMD’s) in this highly skilled group of individuals has been investigated internationally, consistently showing a high injury rate. There is however, a paucity of literature documenting the prevalence of musculoskeletal injuries in South African professional orchestral string players. It is hypothesized that South African trained orchestral string musicians may be at a greater risk for PRMD development due to the unique training and performance environments encountered in this country. Objectives: This study aimed to determine the demographic and injury profile; prevalence rate of current injury and risk factors for musculoskeletal injury in South African professional orchestral string musicians. Method: The study utilized a self administered quantitative questionnaire distributed to all string players in the three professional orchestras in South African in a semi-supervised fashion. SPSS version 15.0 (SPSS Inc., Chicago, Illinois, USA) was used to analyze the data. A p value < 0.05 was considered as statistically significant. iv v Results: There were 27 respondents, with the average participant being a Caucasian, right handed, non-smoking female, 37.11 years of age, 1.5631 meters tall, with a weight of 62.96 kilograms (BMI = 25.768) who exercised regularly (primarily in the gym). A bachelors degree in Music was the most commonly awarded qualification, obtained between the years 2000 and 2009, from a University outside of the Republic of South Africa. The prevalence of PRMD’s in the sample was 63% (n = 17), with a 95% confidence interval of 42.4% to 80.6%.In this study there was a high rate of injury (6.53 PRMD’s per player over a 12 month period), equating to 111 reported injuries in a population of 27 string players. The upper back (defined as the area between the shoulder blades) was the most commonly injured part of the body (77.8%, n = 21), followed by the upper extremity, mainly the shoulder (70.4%, n = 19). No statistically significant relationships were found in determining and confirming expected risk factors in the string players. Conclusion: Professional orchestral string musicians in South Africa suffer from a high rate of injury which is comparable to international studies of the same nature

Submitted in partial compliance with the requirements for the Master’s Degree in Technology: Chiropractic, Department of Chiropractic, Durban University of Technology, Durban, South Africa, 2016. / Background: Tennis is one of the most popular sports globally with over 75 million players around the world. Most studies have focused on junior or elite level players although the majority of players around the world are presumed to be recreational/non-professional players. To date, limited research is available pertaining to the epidemiology of tennis related musculoskeletal in non-professional league tennis players in South Africa. This study aimed to determine the profile of musculoskeletal injuries amongst league tennis players in the northern eThekwini region. Methods: This was a quantitative, cross-sectional, descriptive study utilizing a self-administered questionnaire, developed specifically for this research utilizing an expert group and pilot study. The questionnaire contained sections on demographics, tennis history, training and nutrition, court surface and equipment as well as a section on tennis related musculoskeletal injuries. Risk factors for injury were first tested using chi square tests in the case of categorical variables, and t-tests in the case of continuous variables. In order to assess the relationship between injury and potential risk factors for injury, a binary logistic regression using backward selection based on likelihood ratios was used. Odds ratios and 95% confidence intervals of the variables remaining in the model at the end were reported. A p value <0.05 was used to indicate statistical significance. Results: Eighty league tennis players responded giving a response rate of 70.16%. The period prevalence, and the point prevalence of tennis related musculoskeletal injury was 68.75% and 36.25% respectively. A predominance of injuries to the upper extremity were recorded (49%) compared to the lower extremity (27.5%) and the back and trunk (23.5%). The elbow was the most common anatomical site of injury (21.4%) followed by the shoulder (19.4%), the lumbar spine (17.3%) and the knee (8.2%). Age was considered to be a risk factor for injury (p=0.049) as older players in the study (49.32 (17.547) years of age) were less likely to contract an injury than younger players (48.38 (13.210) years of age). The likelihood of injury decreased with a higher Body Mass Index (p=0.042). The relationship between consumption of spirit alcohol and injury was significant (p=0.043). Ex-smokers had a higher chance of contracting an injury (p=0.013). It was also found that those who cycled weekly were less likely to contract an injury (p=0.040). Conclusion: The results concur with other studies on recreational/non-professional tennis players and add insight into risk factors predisposing this population to injury. Health care practitioners need to understand the risk factors for injury in this population so that players can be better managed. Using the results of the study, an injury prevention strategy such as a strength and conditioning program, needs to be implemented with the goal to reduce or prevent common injuries in this population of players. / M

Submitted in partial compliance with the requirements for the Master’s Degree in Technology: Chiropractic, Department of Chiropractic, Durban University of Technology, Durban, South Africa, 2016. / Background There has been a remarkable increase in the participation of sport for athletes with disabilities. Consequently, there have been many international studies on injuries in athletes which have shown a high prevalence in wheelchair basketball, largely attributed to the fast-paced, high intensity nature of the sport. This sport has grown worldwide including South Africa, however, very little research has been published on South African wheelchair basketball players and more research is, therefore, needed. Aim To determine the prevalence and profile of musculoskeletal pain in elite wheelchair basketball players of different point classifications in South Africa. Hypothesis 1: Upper extremity (including neck and back) pain is experienced more commonly in lower point classified wheelchair basketball players than in higher point classified players. Hypothesis 2: Lower extremity pain is experienced more commonly in higher point classified players than in lower point classified players Method This study was a quantitative, cross-sectional, questionnaire-based study. The questionnaire comprised of sub-sections on demographics and disability characteristics; activity levels pertaining to wheelchair basketball and other sport/physical activity; the prevalence of pain and the impact thereof on wheelchair basketball and/or activities of daily living. This questionnaire was administered to 48 wheelchair basketball players who were competing in the 2015 Supersport League. A response rate of 70% was decided as the lower limit cut-off for statistical power. Results Fourty-three participants responded yielding an 89.58% response rate. The mean age of participants was 33.3 (SD:9.5) years and the majority of participants (n=35) were male and African (n=29). Out of the 43 participants, 79.1% (n=34) used mobility devices, the majority (n=20) used wheelchairs. Most of the participants (n=41) played wheelchair basketball for more than five years and 32 participants did not participate in other sport. Almost half of the participants (n=25) experienced musculoskeletal pain in the last twelve months or at present, 75% of whom (n=12) visited a Physiotherapist for the pain. More than half of these participants (n=15; 60%) reported that the pain negatively affected their basketball performance. It was established that arm pain occurred frequently in lower point classified players (1.0-2.5 point players) and that hand and wrist pain was also more prevalent in lower point players than in higher point players. The prevalence of lower extremity pain was low and there was no statistically significant difference between higher and lower point classified players. Conclusions and Recommendations The finding that upper extremity pain occurred more frequently in lower point classified players was in keeping with the first hypothesis (the null hypothesis was, therefore, rejected). The second hypothesis was, however, rejected (and the null hypothesis was, therefore, accepted) as lower extremity pain did not occur more frequently in higher point classified players than in lower point classified players. The Eta scores may have been higher and may have shown a much larger than typical relationship between point classification and the prevalence of musculoskeletal pain had there been a larger sample size. Notwithstanding this limitation, it is a challenge to obtain a significantly larger sample size due to the nature and limited number of participants in this sport. More studies are warranted on this group of individuals, as a large number experienced pain which affected more than half of the participants’ performance in wheelchair basketball. These studies are important for the future success of the South African players and the sport in South Africa. / M

Submitted in partial compliance with the requirements for a Master’s Degree in Technology, Department of Chiropractic and Somatology, Durban University of Technology, Durban, South Africa, 2016. / Background: Mixed martial arts (MMA) is a contact sport that has grown in popularity worldwide. MMA has been shown to be an activity that generates a high volume of injuries in its participants, especially when subjected to particular factors that are known to carry high risk in contact sports. Limited research has been conducted concerning the risk for injury development in MMA, with no South African statistics being produced to date. This study aims to bridge this gap. Aim: The aim of this study was to determine the prevalence of and risk factors associated with musculoskeletal injuries in Mixed Martial Arts athletes in the greater Durban area of KwaZulu-Natal. Method: This study was a prospective, quantitative survey that sampled 105 MMA athletes from 16 accredited gyms in the greater Durban area. The information captured from the questionnaires enabled compilation of a fighter profile, training profile and injury profile assessing injuries present at the time of data collection and a history of injuries over a 12 month period. Data was analysed with SPSS version 23.0. Inferential techniques included the use of correlations and chi square test values, displayed as p-values and Eta scores. Relationships were considered significant with a p-value of <0.05 and an effect size of >0.23. Results: A 91% response rate was achieved with 83.3% male and 16.2% female participation. Overall, the most commonly injured areas were the upper extremity (36.5%), followed by the lower extremity (34.3%), spine (14.2%), head (8.6%) and trunk (6.5%) regions. In terms of single areas, the most common injuries were to the shoulder (30.9%), knee (29.2%) and elbow (14.4%). The most common injury types were joint sprains (31.1%), muscle strains (20.7%) and ligament tears (18.6%). The most common injury mechanisms were being struck (16.1%), falling (15.7%) and striking an opponent (13.6%). Participants were unsure of the mechanism of their injuries in 7.5% of the injury reports. The number of days missed from training due to injury ranged from zero to 270 days of incapacitation. Risk factors for injury were significant for favoring the dominant hand while fighting (p = 0.011), flexibility training/ stretching (p = 0.019), ground arm-bars (p = 0.014), ground strangles (p = 0.028), groundwork holds/pins (p = 0.028), falling (p = 0.006), increased age (η = 0,619) and increased body weight (η = 0.706). Participation in CrossFit as an additional sport/ conditioning program was a protective factor against injuries (p = 0.007). Conclusion and recommendations: Favouring one side, falling, stretching, arm-bars, strangles, pins and increasing weight are some of the largely modifiable risk factors that play an important role in the development of injuries in MMA athletes. Coaches and their athletes will benefit from adapting training strategies to reduce injury rates from over-exposure to activities that present a high risk of injury as well as by furthering the extent of exposure to conditioning. / M

Thesis (MScPhysio (Physiotherapy))--University of Stellenbosch, 2007. / INTRODUCTION Computer use has been identified as a risk factor for the development of musculoskeletal dysfunction among children and adolescents internationally. Computer exposure has increased in the Western Cape since 2002, with the inception of a project to install computer laboratories in all schools in the province. As musculoskeletal dysfunction experienced during adolescence is predictive of musculoskeletal disorders in adulthood, it is essential to identify all risk and/or associative factors. METHODOLOGY A descriptive study was conducted with the aim to investigate whether the musculoskeletal dysfunction of high school learners in the Cape Metropolitan region was related to their computer use. This study was conducted in two phases. Phase 1 of the study entailed the completion of a new questionnaire, the Computer Usage Questionnaire, by grade 10-12 learners. The learner sample was divided in a computer and a non-computer group depending on their exposure to the school computer. Phase 2 of the study involved the assessment of the ergonomic design of the computer laboratories at randomly selected high schools within the Cape Metropolitan region. RESULTS A total of 1073 learners (65% girls & 35% boys), aged 14-18 years, completed the CUQ in phase 1 of the study. The results indicated that learners in the computer group had greater weekly exposure to computers than the non-computer group. The prevalence of musculoskeletal dysfunction among this learner sample was 74%. The most common body areas of dysfunction were the head, low back and neck. The female gender, playing sport and using the school computer for more than three years were associated with musculoskeletal dysfunction. Weekly computer use of more than seven hours was predictive of general musculoskeletal dysfunction, low back pain and neck pain. Twenty nine computer laboratories within 16 selected high schools were assessed by means of the Computer Workstation Design Assessment (CWDA). Out of a total score of 40, the computer laboratories obtained average scores of less than 45%, indicating compliance with less than half of the standard ergonomic requirements. The average scores for the workspace environment was less than 40%. The design of the desk, chair and computer screen had the poorest compliance to ergonomic guidelines. DISCUSSION AND CONCLUSION The prevalence of musculoskeletal dysfunction among this sample was higher than among other similar samples on the same study topic. The higher prevalence may be attributed to the poor ergonomic design of the computer laboratories in the Cape Metropolitan region. Learners’ reduced participation in activities such as sport and working on a computer due to their musculoskeletal dysfunction, may impact on their choice of a future career. The tendency of learners not to seek medical advice for their musculoskeletal dysfunction may predispose the development of chronic musculoskeletal disorders. Education of related parties on safe computing habits as well as advice on the ergonomic design of computer laboratories is recommended to prevent the progression of adolescent musculoskeletal dysfunction into chronic disorders in adulthood.

Thesis (MSc)--University of Stellenbosch, 2006. / ENGLISH ABSTRACT: Both, the cytokine Tumor Necrosis Factor-α (TNF-α) and the enzyme cytosolic phospholipase A2 (cPLA2) are crucial driving forces in mediating the cellular inflammatory response and are involved in ischaemic injury. During an ischaemic insult, TNF-α is endogenously generated. Apart from the recognized effects of TNF- α, such as the induction of apoptosis, proliferation and differentiation, if present in low dosages, it also mediates cytoprotective effects. Upon activation, cPLA2 contributes to the ischaemic challenge with the generation of mediators of cellular injury and apoptosis. Upon stimulation, this calcium dependent enzyme translocates to the phospholipid compartment of the cell membrane and induces the hydrolysis of sn-2 ester bonds in phospholipids. It governs the release of free fatty acids and lysophospholipids and generates role players of inflammation. We suggest a role for cPLA2 in the TNF-α mediated cytoprotection, with a distinct phosphorylation and translocation pattern. Aims The involvement of cPLA2 in TNF-α mediated cytoprotection in the C2C12 murine skeletal muscle cell line in tolerance to ischaemia was examined. To investigate the nature of the cPLA2 phosphorylation pattern, the mitogen activated protein kinases (MAPKs) p38 and extracellular regulated kinase (ERK) as contributors to cPLA2 phosphorylation and activation, were examined at appropriate time points. To dissect out the cPLA2 interplay and dependencies with these MAPKs within the pathway context, the selective cPLA2 inhibitor arachidonyl trifluoromethyl ketone (AACOCF3) was employed and its effect on cell viability was examined. Fluorescence microscopy was used to substantiate cPLA2 activation, by assessing its cellular distribution, translocation and cell organelle target preference, using co-localization and z-stack techniques. In addition, the induction of the apoptotic pathway through analysis of caspase-3 and poly (ADP-ribose) polymerase (PARP) cleavage was examined. The role of caspase-3 in cPLA2 turnover was addressed employing the caspase inhibitor, Z-DEVD-FMK. Methods Cells were grown in Dulbecco’s Modified Eagles Medium (DMEM) with 10% fetal bovine serum (FBS), and incubated under 5% CO2 conditions, until 50%-70% confluent. Using DMEM supplemented with 1% horse serum, cell differentiation into myotubes was induced. Differentiated cells were preconditioned for 30 min classically, with 0.5 ng/ml TNF-α or the cPLA2 selective inhibitor AACOCF3 (10 μM) respectively. Followed by a 60 min washout period the cells were subjected to 8 hrs simulated ischaemia. Cellular viability; and cPLA2 phosphorylation- and translocation events were assessed using Western blots and advanced immunocytochemistry and imaging techniques. Results Preconditioning with TNF-α, ischaemic preconditioning; and the use of the cPLA2 inhibitor AACOCF3, attenuated the decrease is cell viability brough about by ischaemia. Western blot analysis indicates the induction of the apoptotic pathway with caspase-3 and PARP cleavage. A significantly reduced translocation of pcPLA2 to the nuclear region in the TNF-α preconditioned group compared to the ischaemic group, as reflected by reduced mean nuclear fluorescence intensity, was observed. A z-stack analysis confirmed that the nuclear and endonuclear region was the target organelle for cPLA2. 3-dimensional co-localazation analysis of pcPLA2 with the nuclear marker nucleoporin p62 mirrored these results. Discussion and conclusion Our results provide evidence that there is a role for cPLA2 in TNF-α mediated cytoprotection. Although we do not observe a differential activation pattern in terms of cPLA2 phosphorylation at various time points within the ischaemic event, and no differential inactivation of cPLA2 via caspase-mediated cPLA2 cleavage, we describe a differential cPLA2 translocation pattern, similar to that in IPC. Through inhibition of cPLA2 translocation, a functional cPLA2 inhibition might be achieved. This would imply inhibition of the inflammatory pathway and a subsequent reduction in the generation of inflammatory mediators. In addition we describe an effect of TNF-α preconditioning on the efficacy of the caspase inhibitor Z-DEVD-FMK. Our results shed light on the survival mechanisms employed by the ischaemically challenged cell in a setting of TNF-α mediated cytoprotection. This might lead to novel approaches in the context of inflammation treatment, through agents that control differential cPLA2 trafficking within the cell. / AFRIKAANSE OPSOMMING: Beide, die sitokien “Tumor Necrosis Factor-α (TNF-α)” en die ensiem, sitosoliese fosfolipase A2 (cPLA2) is uiters belangrike bemiddelaars van die sellulêre inflammatoriese respons en is verder ook betrokke by isgemiese selskade. TNF-α word endogeen gegenereer tydens ‘n isgemiese intervensie. Afgesien van ‘n verskeidenheid effekte, soos die inisiëring van apoptose, sel-proliferasie en - differensiasie, bemiddel dit ook selbeskermende meganismes indien dit in lae konsentrasies in die sel teenwoordig is. Na aktivering dra cPLA2 by tot die isgemiese intervensie deur die vorming van bemiddelaars van selskade en apoptose. Hierdie kalsium-afhanklike ensiem translokeer na die fosfolipied membraankomponent na stimulering en induseer die hidrolise van die sn-2 esterbinding in die fosfolipied. Die vrystelling van vry vetsure en lisofosfolipiede word sodoende bewerkstellig wat verder gemetaboliseer kan word tot inflammatoriese bemiddelaars. Ons stel voor dat cPLA2 ‘n rol in TNF-α bemiddelde selbeskerming speel en dat dit gepaardgaan met kenmerkende fosforilerings- en translokeringspatrone. Doelwitte Die rol van cPLA2 tydens TNF-α bemiddelde selbeskerming is in ‘n C2C12 skeletspiersellyn na blootstelling aan isgemie ondersoek. Die rol van die MAPKs, p38 en ERK, is ondersoek om vas te stel of hulle betrokke is by die aktivering van cPLA2. Die selektiewe cPLA2 inhibitor, AACOCF3, is gebruik om te bepaal of die fosforilering van MAPKs ook cPLA2-afhanklik is. Die sellulêre cPLA2 verspreiding, translokering en teiken selorganelle is ook ondersoek met behulp van fluoresensie mikroskopie deur gebruik te maak van ko-lokalisering en z-plaat tegnieke. Verder, is die indusering van die apoptotiese paaie ondersoek deur tegnieke wat kaspase- en PARP kliewing meet. Die kaspase inhibitor, Z-DEVD-FMK, is gebruik om vas te stel of kaspase-3 ‘n rol speel in cPLA2 kliewing in ons selmodel. Metodes Selle is gekweek in Dulbecco’s gemodifiseerde Eagles Medium (DMEM) waarby 10% fetale kalf serum (FBS) gevoeg is, en wat geïnkubeer is in 5% CO2 totdat dit 50%-70% konfluent was. Die selle is verder gedifferensieer in miobuise deur gebruik te maak van DMEM waarby 1% perdeserum gevoeg is. Gedifferensieerde selle is vir 30 min klassiek geprekondisioneer asook respektiewelik met 0.5 ng/ml TNF-α en die cPLA2 selektiewe inhibitor, AACOCF3 (10 μM). Na ‘n 60 minute uitwas periode is die selle blootgestel aan 8 h gesimuleerde isgemie. Sellulêre lewensvatbaarheid, cPLA2 fosforilering- and translokering is ondersoek deur onderskeidelik gebruik te maak van die “Western” klad metode en gesofistikeerde immunositochemiese beeld tegnieke. Resultate Prekondisionering met TNF-α, isgemiese prekondisionering asook inhibisie van as cPLA2 met die inhibitor, AACOCF3, het ‘n beduidende toename in sellewensvatbaarheid tot gevolg gehad. Daar is ook dmv die “Western” klad tegniek bewys dat apoptose geïduseer word deur middel van kaspase-3- en PARP kliewing. Daar is insiggewend minder translokasie van cPLA2 na die nukluêre fraksie in die isgemiese groep in vergelyking met die TNF-α geprekondisioneerde groep waargeneem (die gemiddelde nukluêre fluoreserende intensiteit is bepaal om voorafgaande feit te staaf). Die cPLA2 teiken organel is geverifieer as die nukleus en die endonukluêre gebied deur middel van z-plaat analises. Drie-dimensionele kolokaliserings analises van pcPLA2 met die nukluêre merker, nucleoporin p62 het hierdie resultate bevestig. Bespreking en Gevolgtrekking Ons resultate verskaf bewyse vir ‘n rol vir cPLA2 in TNF-α bemiddelde selbeskerming. Alhoewel daar nie ‘n differensiële aktiveringspatroon in terme van cPLA2 fosforilering tydens verskeie tydspunte in die isgemiese intervensie waargeneem is nie, en ook geen kaspase-3 bemiddelde kliewing van cPLA2 nie, word ‘n differensiële translokeringspatroon soorgelyk aan die isgemiese prekondisioneringsgroep, waargeneem. Funsksionele cPLA2 inhibisie kan dus moontlik bewerkstellig word deur inhibisie van cPLA2 translokasie. Die inflammatoriese respons kan dus moontlik so inhibieer word en die vorming van minder inflammatoriese bemiddelaars tot gevolg hê. Verder het TNF-α prekondisionering ook ‘n effek op die effektiwiteit van die kaspase-inhibitor, ZDEVD- FMK. Ons resultate werp ook lig op die meganismes wat deur selle onder isgemiese toestande uitgeoefen word tydens TNF-α bemiddelde selbeskerming. Hierdie resultate mag lei tot nuwe benaderings in die konteks van behandeling teen inflammasie deur gebruik te maak van middels wat cPLA2 translokering in die sel beheer.

Thesis (MSc (Physiological Sciences))--Stellenbosch University, 2008. / Introduction: Skeletal muscle atrophy is a mitigating complication that is characterized by a reduction in muscle fibre cross-sectional area as well as protein content, reduced force, elevated fatigability and insulin resistance. It seems to be a highly ordered and regulated process and signs of this condition are often seen in inflammatory conditions such as cancer, AIDS, diabetes and chronic heart failure (CHF). It has long been understood that an imbalance between protein degradation (increase) and protein synthesis (decrease) both contribute to the overall loss of muscle protein. Although the triggers that cause atrophy are different, the loss of muscle mass in each case involves a common phenomenon that induces muscle proteolysis. It is becoming evident that interactions among known proteolytic systems (ubiquitin-proteosome) are actively involved in muscle proteolysis during atrophy. Factors such as TNF-α and ROS are elevated in a wide variety of chronic inflammatory diseases in which skeletal muscle proteolysis presents a lethal threat. There is an increasing body of evidence that implies TNF-α may play a critical role in skeletal muscle atrophy in a number of clinical settings but the mechanisms mediating its effects are not completely understood. It is also now apparent that the transcription factor NF-κB is a key intracellular signal transducer in muscle catabolic conditions. This study investigated the various proposed signalling pathways that are modulated by increasing levels of TNF-α in a skeletal muscle cell line, in order to synthesize our current understanding of the molecular regulation of muscle atrophy. Materials and Methods: L6 (rat skeletal muscle) cells were cultured under standard conditions where after reaching ± 60-65% confluency levels, differentiation was induced for a maximum of 8 days. During the last 2 days, myotubes were incubated with increasing concentrations of recombinant TNF-α (1, 3, 6 and 10 ng/ml) for a period of 40 minutes, 24 and 48 hours. The effects of TNF-α on proliferation and cell viability were measured by MTT assay and Trypan Blue exclusion technique. Morphological assessment of cell death was conducted using the Hoechst 33342 and Propidium Iodide staining method. Detection of apoptosis was assessed by DNA isolation and fragmentation assay. The HE stain was used for the measurement of cell size. In order to determine the source and amount of ROS production, MitoTracker Red CM-H2 X ROS was utilised. Ubiquitin expression was assessed by immunohistochemistry. PI3-K activity was calculated by using an ELISA assay and the expression of signalling proteins was analysed by Western Blotting using phospho-specific and total antibodies. Additionally, the antioxidant Oxiprovin was used to investigate the quantity of ROS production in TNF-α-induced muscle atrophy. Results and Discussion: Incubation of L6 myotubes with increasing concentrations of recombinant TNF-α revealed that the lower concentrations of TNF-α used were not toxic to the cells but data analysis of cell death showed that 10 ng/ml TNF-α induced apoptosis and necrosis. Long-term treatment with TNF-α resulted in an increase in the upregulation of TNF- α receptors, specifically TNF-R1. The transcription factors NF-κB and FKHR were rapidly activated thus resulting in the induction of the ubiquitin-proteosome pathway. Activation of this pathway produced significant increases in the expression of E3 ubiquitin ligases MuRF-1 and MAFbx. Muscle fibre diameter appeared to have decreased with increasing TNF-α concentrations in part due to the suppressed activity of the PI3-K/Akt pathway as well as significant reductions in differentiation markers. Western blot analysis also showed that certain MAPKs are activated in response to TNF-α. No profound changes were observed with ROS production. Finally, the use Oxiprovin significantly lowered cell viability and ROS production. These findings suggest that TNF-α may elicit strong catabolic effects on L6 myotubes in a dose and time dependent manner. Conclusion: These observations suggest that TNF-α might have beneficial effects in skeletal muscle in certain circumstances. This beneficial effect however is limited by several aspects which include the concentration of TNF-α, cell type, time of exposure, culture conditions, state of the cell (disturbed or normal) and the cells stage of differentiation. The effect of TNF-α can be positive or negative depending on the concentration and time points analysed. This action is mediated by various signal transduction pathways that are thought to cooperate with each other. More understanding of these pathways as well as their subsequent upstream and downstream constituents is obligatory to clarify the central mechanism/s that control physiological and pathophysiological effects of TNF-α in skeletal muscle.

Thesis (PhD)--University of Stellenbosch, 2005. / ENGLISH ABSTRACT: Skeletal muscle adapts to stimuli by modifying structural and metabolic protein expression. Furthermore, a muscle group may vary within itself to accommodate specialisation in regions. Structural and metabolic characteristics of an individual are regulated partly by genotype, but contraction duration and intensity may play a greater role in muscle phenotype. The aims of this dissertation were to investigate: structural and metabolic regionalisation in a muscle group, possible relationships between training volume and intensity and hybrid fibres, muscle characteristics of athletes from two different ethnic groups, and muscle adaptation in already well-trained athletes subjected to high intensity interval training. Myosin heavy chain (MHC) isoform content and citrate synthase (CS) activities were measured in the Quadriceps femoris (QF) muscle of 18 female rats. Muscle was divided into superficial, middle and deep, distal, central and proximal parts. MHC IIb and IIx were more abundant in superficial regions (P < 0.05) with low CS activities compared to deeper parts. Isoform content varied along the length of deep regions. This study showed that the QF has regional specialisation. Therefore, standardisation of sampling site is important. Hybrid fibre proportions in muscle biopsies of 12 middle distance runners and 12 non-runners were investigated. MHC IIa/IIx correlated with training volume/week in runners (r = -0.66, P < 0.05) and MHC IIa/IIx correlated with exercise hours/week in non-runners (r = -0.72, P < 0.01). Average preferred racing distance (PRDA) correlated better with MHC IIa/IIx in runners (r = -0.85, P < 0.001). MHC IIa/IIx may therefore be more closely related to exercise intensity than previously thought. Fibre type characteristics and performance markers were investigated in 13 Xhosa and 13 Caucasian distance runners, matched for performance, training volume and PRDA. Xhosa runners had less MHC I and more MHC IIa fibres in muscle biopsies than Caucasian runners (P < 0.05). Xhosa runners had lower plasma lactate at 80% peak treadmill speed (PTS) (P < 0.05), but higher lactate dehydrogenase (LDH) (P < 0.01) and phosphofructokinase (P = 0.07) activities in homogenate muscle samples. LDH activities in MHC I (P = 0.05) and IIa (P < 0.05) fibre pools were higher in Xhosa runners. Xhosa athletes may thus have a genetic advantage or they may have adapted to running at a higher intensity. Six weeks of individually standardised high intensity interval treadmill training (HIIT) were investigated in 15 well-trained runners. PTS increased after HIIT (P < 0.01), while maximum oxygen consumption (VO2max) only showed a tendency to have increased as a result of HIIT (P = 0.06). Sub-maximal tests showed lower plasma lactate at 64% PTS (P = 0.06), with lower heart rates at workloads from 64% to 80% PTS (P < 0.01) after HIIT. No changes were observed for cross-sectional area, capillary supply and enzyme activities in homogenates muscle samples. LDH activity showed a trend (P = 0.06) to have increased in MHC IIa pools after HIIT. Higher HIIT speed was related to decreases in MHC I fibres, but increases in MHC IIa/IIx fibres (r = -0.70 and r = 0.68, respectively, P < 0.05). Therefore, HIIT may alter muscle fibre composition in well-trained runners, with a concomitant improvement in performance markers. / AFRIKAANSE OPSOMMING: Skeletspier kan adapteer deur strukturele en metaboliese protein ekspressie te verander as gevolg van stimulante. ‘n Spiergroep kan ook intern verskil om spesialisering in spierdele toe te laat. Strukturele en metaboliese karaktereienskappe van ‘n individu word deels gereguleer deur gene, maar kontraksie tydperk en intensiteit mag ‘n groter rol speel in spierfenotipe. Die doelwitte van hierdie tesis was om ondersoek in te stel in: strukturele en metaboliese eienskappe in spiergroepstreke, moontlike verhoudings tussen oefeningsvolume of intensiteit en baster vesels, spier eienskappe in atlete van twee etniese groepe, en spier adaptasie in goed geoefende atlete blootgestel aan hoë intensiteit interval oefening. Miosien swaar ketting (MSK) isovorm inhoud en sitraat sintase (SS) aktiwiteite is gemeet in die Quadriceps femoris (QF) spier van 18 wyfie rotte. Spiere was opgedeel in oppervlakkig, middel en diep, asook distaal, sentraal en proksimale dele. MSK IIb en IIx was meer oorvloedig in oppervlakkige dele (P < 0.05) met lae SS aktiwiteite in vergelyking met dieper dele. Isovorm inhoud het ook verskil oor die lengte van diep dele. Dus bevat die QF gespesialiseerde streke en is die area van monsterneming belangrik. Baster vesel proporsies is ondersoek in spiermonsters van 12 middel afstand hardlopers en 12 niehardlopers. MSK IIa/IIx van hardlopers het met oefeningsvolume/week gekorreleer (r = -0.66, P < 0.05), asook MSK IIa/IIx van nie-hardlopers met oefeningsure/week (r = -0.72, P < 0.01). Gemiddelde voorkeur wedloop afstand (VWAG) het beter met MSK IIa/IIx gekorreleer in hardlopers (r = -0.85, P < 0.001). MSK IIa/IIx mag dus meer verwant wees aan oefeningsintensiteit. Veseltipe eienskappe en prestasie merkers was ondersoek in 13 Xhosa en 13 Caucasian langafstand atlete, geëweknie vir prestasie, oefeningsvolume en VMAG. Xhosa hardlopers het minder tipe I en meer tipe IIA vesels in hul spiermonsters gehad as die Caucasian hardlopers (P < 0.05). Xhosa hardlopers het laer plasma laktaat by 80% van hul maksimale trapmeul spoed (MTS) (P < 0.05), maar hoër laktaat dihidrogenase (LDH) (P < 0.01) en fosfofruktokinase (P = 0.07) aktiwiteite in homogene spiermonsters gehad. LDH aktiwiteite in MSK I (P = 0.05) en IIa (P < 0.05) veselbondels was hoër in Xhosa hardlopers. Xhosa atlete mag dus ‘n genetiese voorsprong geniet, of hulle het geadapteer om by hoër intensiteite te hardloop. Ses weke van geïndividualiseerde gestandardiseerde hoë intensiteit interval trapmeul oefening (HIIT) was ondersoek in 15 goed geoefende hardlopers. MTS het verhoog na HIIT (P < 0.01), en maksimale surrstof verbruik (VO2max) het ‘n neiging getoon om te verhoog het na HIIT (P = 0.07). Submaksimale toetse het laer plasma laktaat by 64% MTS getoon (P = 0.06), met laer harttempos by werkladings 64% tot 80% MTS (P < 0.01). Geen veranderings was gemerk vir deursnit area, kapillêre toevoer en ensiem aktiwiteite in homogene spiermonsters nie. LDH aktiwiteit het ‘n neiging getoon om te verhoog het (P = 0.06) in MSK IIa veselbondels na HIIT. Hoër HIIT snelhede was verwant aan ‘n daling in MSK I vesels, maar ‘n verhoging in MSK IIa/IIx vesels (r = -0.70 en r = 0.68, respektiwelik, P < 0.05). HIIT mag dus spier veseltipe verander in goed geoefende hardlopers, met gevolglike verbetering in prestasie merkers.

published_or_final_version / Medical Sciences / Master / Master of Medical Sciences