No description available.

Most of the load-bearing demand placed on the human body is transduced by skeletal tissue, and the capacity of the skeleton to articulate in various opposing directions is essential for body movement and locomotion. Consequently, cartilage and bone defects due to trauma, disease, and developmental abnormalities result in disabling pain and immobility for millions of people worldwide. A novel way of promoting cartilage and bone regeneration is through the incorporation of either primary cells or multipotent progenitor cells in a three-dimensional (3D) biomaterial scaffold, and/or the addition of exogenous growth and differentiation factors. The first part of this study reports a protocol for using freshly isolated mature chondrocytes seeded in a 3D hydrogel biomaterial scaffold, developed to explore mechanotransduction of engineered cartilage constructs cultured in a designed bioreactor. The bioreactor was designed to allow the application of physiological mechanical forces (compression and fluid flow), as well as a non-invasive/non-destructive method for analyzing regenerating tissue in real time through ultrasound transducers and a computerized monitoring system. In the second part of this study, an engineered immortalized osteoprecursor cell line, designated OPC1 (osteoblastic precursor cell line 1), was used as a culture model system for exploring the effects of exogenous growth and differentiation factors, mainly vitamin D, on early bone development. OPC1 was previously designed to provide a consistent reproducible culture system for direct comparisons of engineered bone constructs, evaluating bone development and cell/biomaterial interactions, and for investigating putative bone differentiating factors. One of the objectives of this research effort was to explore tissue development and regeneration by culturing OPC1 in the presence of vitamin D metabolites vitaD3 and 1,25OH2D3, while assaying the concomitant biological response. Results indicate that OPC1 is capable of metabolizing the parental metabolite vitaD3, and thus 25OHD3, to the active vitamin D form 1,25OH2D3. The metabolism of vita3 resulted in an anti-proliferative and pro-differentiative influence on OPC-1. These results support the hypothesis that extra-endocrine synthesis of 1,25OH2D3 functions in a tissue specific manner to regulate growth and differentiation, in addition to the classic calcimic actions of the vitamin D endocrine pathway. Understanding the influence of vitamin D on bone development will have significant implications on healthy aging, including the susceptibility to skeletal disorders involved in development and aging, such as osteoarthritis (OA) and osteoporosis.

In the run-up to biomechanical testing, fresh human tissue samples are often frozen in order to inhibit initial decomposition processes and to achieve a temporal independence of tissue acquisition from biomechanical testing. The aim of this study was to compare the mechanical properties of fresh tissue samples of the human iliotibial tract (IT) to fresh-frozen samples taken from the same IT and those modified with different concentrations of Dimethylsulfoxide (DMSO) prior to freezing. All samples were partial plastinated and destructive tensile tests were conducted with a uniaxial tensile test setup. A plastination technique already established in the laboratory was modified to improve the clamping behaviour of the samples. Material failure was caused by a gradual rupture of the load-bearing collagen fibre bundles. Contrary to our expectations, no significant difference was found between the tensile strength of fresh and fresh frozen specimens. The addition of 1 wt% DMSO did not increase the tensile strength compared to fresh-frozen samples; an addition of 10 wt% DMSO even resulted in a decrease. Based on our findings, the use of simple fresh-frozen specimens to determine the tensile strength is viable; however fresh specimens should be used to generate a complete property profile.

Indiana University-Purdue University Indianapolis (IUPUI) / Study has shown that plasma membrane (PM) cholesterol and cortical filamentous actin (F-actin) influence skeletal muscle glucose transport. Of fundamental and clinical interest is whether diabetogenic insults promote membrane/cytoskeletal dysfunction amendable for therapy. As exposure to excess fatty acid (FA)s induce glucose intolerance by mechanisms imperfectly understood, we tested if PM cholesterol/F-actin changes could contribute to FA-induced glucose transporter GLUT4 dysregulation in skeletal muscle. High-fat fed, insulin-resistant animals displayed elevated levels of skeletal muscle PM cholesterol and a loss in cortical F-actin, compared to normal-chow fed animals. Consistent with a PM cholesterol component of glucose intolerance, human skeletal muscle biopsies revealed an inverse correlation between PM cholesterol and whole-body glucose disposal. Mechanistically, exposure of L6 myotubes to the saturated FA palmitate induced an increase in PM cholesterol that destabilized actin filaments and decreased insulin-stimulated PM GLUT4 and glucose transport, which could be reversed with cholesterol lowering. Next, study tested if the lipid-lowering action of the antidiabetic AMP-activated protein kinase (AMPK) had a beneficial influence on PM cholesterol balance. Consistent with AMPK inhibition of 3-hydroxy-3-methylglutaryl CoA reductase, a rate-limiting enzyme of cholesterol synthesis, we found that AMPK activation promoted a significant reduction in PM cholesterol and amplified basal and insulin-stimulated GLUT4 translocation. A similar loss of PM cholesterol induced by β-cyclodextrin caused an analogous enhancement of GLUT4 regulation. Interestingly, PM cholesterol replenishment abrogated the AMPK effect on insulin, but not basal, regulation of GLUT4 translocation. Conversely, AMPK knockdown prevented the enhancement of both basal and insulin-stimulated GLUT4 translocation. As a whole these studies show PM cholesterol accrual and cortical F-actin loss uniformly in skeletal muscle from glucose-intolerant mice, swine, and humans. In vivo and in vitro dissection demonstrated this membrane/cytoskeletal derangement induces insulin resistance and is promoted by excess FAs. Parallel studies unveiled that the action of AMPK entailed lowering PM cholesterol that enhanced the regulation of GLUT4/glucose transport by insulin. In conclusion, these data are consistent with PM cholesterol regulation being an unappreciated aspect of AMPK signaling that benefits insulin-stimulated GLUT4 translocation during states of nutrient excess promoting PM cholesterol accrual.

Objective: The purpose of this study was to determine inter-rater and intra-rater reliability of synchronous ultrasound imaging and electromyography measures of lumbopelvic-hip muscle activity performed by a novice and an experienced investigator in healthy individuals. Electromyography (EMG) has served as the gold standard for quantification of onset of muscle activation; however, ultrasound imaging can visualize muscle activity when collected simultaneously. Methods: A novice and experienced investigator collected a series of 3 ultrasound images at rest and 3 M-mode clips during contraction of each muscle while EMG electrodes collected muscle activity. Muscles collected included: external oblique, erector spinae, rectus abdominis, gluteus maximus, and gluteus medius. Participants were asked to return 48-72 hours for a second session. After all muscles were collected, muscle thickness was measured from the US images and latency based on onset of activity from EMG was processed and averaged. Results: Moderate inter-rater reliability (ICC2,k=.5-.7) was found for most thickness, modulated thickness, and latency variables between the experienced and novice raters, however rectus abdominis had poor reliability compared to the other muscles assessed. Intra-rater reliability between sessions 1 and 2 for the novice rater revealed moderate reliability (ICC2,k=.5-.7) in the abdominal muscles (external oblique, erector spinae, contracted rectus abdominis) and poor reliability in the gluteal muscles. Conclusions: Modulated thickness values had the strongest reliability for inter- and intra-rater reliability, when thickness measures were divided by body weight in kilograms before analysis. Subcutaneous tissue, notably abdominal adipose, and its role on participant positioning should receive added attention during training and instruction of novice investigators during M-mode acquisition and timing of contraction with EMG synchronization.

No description available.

Thesis (PhD)--Stellenbosch University, 2012. / Includes bibliography / ENGLISH ABSTRACT: Introduction: The increased prevalence of adolescent upper quadrant musculoskeletal pain (UQMP) is becoming a great concern to health professionals. The risk factors associated with adolescent UQMP are complex and multifactorial, including, among others sitting as a physical risk factor. However, no evidence exists to support sitting postural angles as a potential predictive factor for adolescent UQMP in computing high school students. Thus, the current project aimed to describe the three-dimensional (3D) sitting postural angles of computing South African high school students in a real-life setting, using a well-tested and documented posture measurement instrument. Methodology: This research project is comprised of seven related studies. Part I of the dissertation presents a systematic review describing the reliability and validity testing of posture measurement instruments. This is followed by three primary correlation and repeated measures observational studies aimed at ascertaining the reliability and validity of a newly developed 3D Posture Analysis Tool (3D-PAT) in the measurement of nine sitting postural angles of computing high school students. Part II of the dissertation presents a systematic review, that evaluates the latest published research evidence of whether sitting is related to UQMP, and, if so, to identify the elements of sitting that significantly contribute to UQMP. This review is followed by a description of a cohort study, with a prospective period of one year. The 3D-PAT was implemented in a clinical research setting in order to measure the 3D sitting posture of a cohort of asymptomatic computing high school students and in order to assess the outcome, seated-related UQMP, prospectively. The prospective study design enabled the research project to contribute to an understanding of any causative relationship between the exposure (sitting postural angles) and the outcome (seated-related UQMP) in a subgroup of adolescents (computer users). Results: After the first phase of psychometric testing of the 3D-PAT using high school students, the findings indicated that the instrument required modifications prior to further psychometric testing. The second phase of testing revealed that the 3D-PAT compared very well with the reference standard for measurement of the X-, Y- and Z-coordinates of the reflective markers on a mannequin. The findings from the phase three study, again using high school students, indicated that the 3D-PAT compared very well with the reference standard and justified its use for the measurement of six sitting postural angles of the upper quadrant in computing high school students. For the cohort study, a 60% response rate for participation was achieved at baseline, with 98% of the students participating at six-month and 80% at one-year follow up. Of the students, 33.5% complained of seated-related UQMP during the follow-up period. Exposure to increased head flexion (>80°) (ρ=0.0001) and the combination of increased head flexion and decreased cranio-cervical angles (ρ=0.007) were significant predictors of seated-related UQMP for those computing high school students complaining of pain greater than the 90th percentile for such. Conclusion: The project described in the current dissertation is the first research project to assess sitting postural angles in asymptomatic high school students, while they worked on desktop computers in a school computer classroom and to assess UQMP prospectively. The research project reports a causal relationship between increased head flexion and seated-related UQMP as increased head flexion was found to be a predictor of seated-related UQMP developing within six to 12 months for computing high school students with a pain score equal or greater than the 90th percentile for pain. The research project emphasises that further research is warranted to investigate the causal pathway between sitting posture and adolescents’ UQMP. / AFRIKAANSE OPSOMMING: Inleiding: Die stygende voorkoms van boonste-kwadrant muskuloskeletale-pyn (BKMP) onder adolessente is besig om ’n groot bron van kommer vir professionele gesondheidswerkers te word. Die risiko-faktore waarmee adolessente BKMP gepaard gaan, is kompleks en multifaktories. Dit sluit onder andere sit as ’n fisiese risiko-faktor in. Daar is egter nog geen bewyse om sittende posturale hoeke as potensiële voorspeller van adolessente BKMP te ondersteun nie. Dus beoog hierdie projek om die drie-dimensionele (3D) sittende posturale hoeke van Suid-Afrikaanse hoërskoolleerders wat ook rekenaargebruikers is, in ’n werklike omgewing te beskryf, deur gebruik te maak van ’n instrument wat postuur meet en wat goed getoets en gedokumenteerd is. Metodiek: Hierdie navorsingsprojek is saamgestel uit sewe studies. Gedeelte I van die proefskrif bied ’n sistematiese oorsig van betroubaarheids- en geldigheidstoetsing van instrumente wat postuur meet. Dit word gevolg deur drie primêre korrelasie studies en studies vir die waarneming van herhaalde meting wat die betroubaarheid en geldigheid van n nuut-ontwikkelde 3D instrument vir posturale analise (3D-PAT) bepaal, wanneer nege sittende posturale hoeke van hoërskoolleerders wat rekenaars gebruik, gemeet word. Gedeelte II van die proefskrif bied ’n sistematiese oorsig van die jongste gepubliseerde navorsing om te evalueer of daar bewyse is dat sit verband hou met BKMP, en, indien wel, om die elemente van sit wat betekenisvol bydra tot BKMP, te identifiseer. Die sistematiese oorsig word deur ’n beskrywing van ‘n jaarlange kohortstudie gevolg. Die 3D-PAT is gebruik in ’n kliniese-navorsingsraamwerk om die 3D-sitpostuur van ’n kohort simptoomvrye hoërskoolleerders wat rekenaargebruikers is, te meet en sitverwante BKMP as uitkoms in die vooruitsig te stel. Die studie ontwerp het dit vir die navorsingsprojek moontlik gemaak om ’n insiggewende bydrae te lewer tot begrip vir enige oorsaaklikheidsverwantskap tussen die blootstelling (sittende posturale hoeke) en die uitkoms (sitverwante BKMP) in ’n subgroup van adolessente (rekenaargebruikers). Resultate: Na afloop van die eerste psigometriese toesting van die 3D-PAT, waarin hoërskoolleerders gebruik is, het bevindings daarop gedui dat die instrument verander moet word voordat toetsing kan voortgaan. Die tweede fase van toetsing het getoon dat die 3D-PAT baie goed vergelyk met die verwysingstandaard vir die meet van die X-, Y- en Z-koördinate van die reflektiewe merkers op ’n mannekyn. Die bevindings van die derde fase van die studie, waartydens hoërskoolleerders weer gebruik is, het aangedui dat die 3D-PAT baie goed vergelyk met die verwysingstandaard. Dit het die gebruik van die instrument om ses sittende posturale hoeke van die boonste kwadrant van hoërskoolleerders wat rekenaars gebruik te meet, bevestig. Die kohortstudie het ’n 60%-reaksiesyfer vir deelname behaal tydens die basislynmetings, waarvan 98% leerders deelgeneem het aan die sesmaande-opvolgmetings en 80% aan die eenjaaropvolgmetings. ’n Totaal van 33.5% van die leerders het gekla van sitverwante BKMP gedurende die eenjaar opvolgperiode. Blootstelling aan ’n vergrootte kopfleksie-hoek (>80°) (ρ = 0.0001) en die kombinasie van ’n vergrootte kopfleksie- en verminderde kranio-servikale hoek (ρ = 0.007) was betekenisvolle voorspellers van sitverwante BKMP vir die hoërskoolleerders wat rekenaars gebruik en kla van groter pyn as die 90ste persentiel daarvan. Gevolgtrekking: Hierdie projek is die eerste navorsing wat sittende posturale hoeke van simptoomvrye hoërskoolleerders wat op tafelrekenaars in die skool se rekenaarklaskamer werk, meet en BKMP voorspel. Die navorsingsprojek rapporteer ‘n oorsaaklikheidsverwantskap tussen ‘n vergrootte kopfleksie-hoek en sitverwante BKMP omdat vergrootte kopfleksie ‘n voorspeller is van sitverwante BKMP wat binne ses tot 12 maande by hoërskoolleerders wat rekenaars gebruik, met ‘n pyntelling gelyk of groter as die 90ste persentiel van pyn, ontwikkel. Die navorsingsprojek beklemtoon dat verdere navorsing om die oorsaaklikheidsroete tussen sitpostuur en adolessente BKMP te ondersoek, geregverdig is. / Medical Research Council of South Africa / National Research Fund / Division of Research Development and Support of Stellenbosch University

So, Chun Lung. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 178-196). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese; appendix in Chinese.

Submitted in partial compliance with the requirements for the Master’s Degree in Technology: Chiropractic, Durban University of Technology, Durban, South Africa, 2018. / Background: Rhythmic Gymnastics is a sporting discipline involving the use of an apparatus (hoop, ball, clubs, ribbon or rope) to a choreographed routine with music. It requires agility, grace, co-ordination and most of all flexibility. Safety in Rhythmic Gymnastics is questionable when one takes training hours and the extreme flexibility required into consideration. An awareness and understanding of the prevalence and risk factors in Rhythmic Gymnastics will allow event organisers, medical personnel, managers, and coaches to adapt training approaches that will minimize the development of injuries. This information will also aid in developing monitoring systems to prevent adaptation injuries, which will lead to safer training and better management of gymnasts Objectives: This study aimed to investigate the prevalence of musculoskeletal injuries in rhythmic gymnasts within the eThekwini municipality and to identify selected factors associated with an increased risk of injury, in order to improve the management of gymnasts. Methods: A quantitative, descriptive questionnaire-based survey with a Beighton Score assessment was conducted on 67 Rhythmic gymnasts in the eThekwini municipality. Statistical analysis was performed on the results obtained from the questionnaire and the Beighton Score using IBM SSS version 23.0. The Chi-squared test was used (Fisher’s Exact Test was used when the Chi-squared test was violated); A p value of less than 0.05 was considered as statistically significant. Graphical representation of scores by groups was done using various types of tables and graphs. Risk factors for injuries were assessed using logistic regression. Factors were entered individually into the model to determine the co- efficients and odds ratios. Trend tests were computed in order to better assess associations between specific factors and injury. Results: A 100% response rate was achieved in this study. The average age of the participants was 12.3 years (95% CI= 11.7-12.8), average height was 148.5 centimetres (95% CI= 145.1-151.9), average weight was 41.0 kilograms (95% CI= 38.3-43.7), the average level of performance was 4.9 (95% CI= 4.1-5.8) and the average Beighton Score was 5.8 (95% CI= 5.3-6.3). The most commonly previously injured areas were the ankle (n=25) (14.0%), hip and knee (each n=19) (each 10.6%) and the low back (n=18) (10.1%). When considering the two most severe previous injuries the results stay similar, with the ankle being most commonly injured (n=15) (28.0%), followed by the hip (n=9) (17.0%) and the knee (n=6) (11.0%). When considering current injuries, the most commonly injured area is the knee and low back (each n=11) (each 14.5%), and the hip and ankle (each n=9) (each 11.8%). From the above it can be deduced that RG results in more injuries to the lower limb than the upper limb, or core/abdomen or the spine. The most common types of RG injury were muscle strains (n=16) (23.9%), followed by unsure (n=9) (13.4%) and joint sprains (n=8) (11.9%). The most common cause of injury for both previous and current RG injuries were overstretching and overuse ((n=23) (34.3%) for previous injuries; (n=15) (22.4%) for current injuries). Risk factors for injury were significant for the following: training hours per week (36.5 times for 5-8 hours of training per week; 15.7 times for under five hours of training per week; both when compared to more than 8 hours) and lack of balance skills included in RG training (4.5 times more likely than not). When considering treatment option used to keep the body in a good condition, a participant was 4.3 times more likely to utilize home remedies than any other treatment option. Trend tests noted that there is an increase in the mean of injuries as one goes up in age, up until a certain age (13-14 years of age for current injuries; 15-16 years of age for previous injuries), thereafter, there is a decease. Trend tests were also constructed for training hours per week; there was a directly proportional relationship between training hours per week and injury. Conclusion: When considering risk of injury in RG, many of the risk factors cannot be modified (such as age). Those risk factors that can be modified (such as training amount and components of training) should be considered by gymnasts and their coaches in order to implement strategies that could prevent injury. / M

Background: Obesity-induced alterations in biomechanics and muscle recruitment during activities of daily living, such as sit-to-stand (STS) are often attributed to increases in adipose tissue (AT) mass. Central or peripheral distribution of AT may differently affect biomechanics and muscle recruitment. Methods: Fifteen healthy, normal weight (BMI 22.4 ± 1.9 kg/m2, 24.1 ± 4.2 years) subjects volunteered. External loads equivalent to a 5 kg/m2 BMI increase were applied in three conditions: unloaded (UN), centrally loaded (CL), and peripherally loaded (PL). Subjects completed three successful STS movements in a backless chair under each load condition in random order. Motion analysis and lower extremity surface electromyography (EMG) were measured. Results: Compared to UN and CL, PL significantly increased support width during STS. PL also significantly increased maximum trunk flexion compared to CL. Peak and total VM EMG activity were significantly increased during CL, compared to UN and PL. During CL, peak VL EMG activity was significantly greater than UN. Conclusions: Central and peripheral weight gain induce different biomechanical adaptations during STS. Central weight gain increases knee extensor muscle activity during STS independent of biomechanical changes. In contrast, peripheral weight gain increases support width and trunk flexion with minimal EMG changes during STS.