Browsing by Department "Department of Human Biology"

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    3D cine DENSE MRI: ventricular segmentation and myocardial stratin analysis
    (2013) Auger, Daniel A; Spottiswoode, Bruce S
    Includes abstract. Includes bibliographical references.
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    A comparison of the pacing profiles adopted by male runners in the Comrades Marathon up run
    (2024) Manchip, Genine; Bosch, Andrew
    Introduction Ultramarathon running is gaining popularity worldwide. Due to the difficulty in completing an ultramarathon, knowledge of the most effective pacing to adopt in an ultramarathon race would be invaluable to coaches and runners, as well as of academic interest, since this information is already well established for the standard marathon. The Comrades Marathon is a globally recognised ultramarathon that takes place in South African annually. Its history and difficult undulating route attracts runners of all abilities, from around the world. Adopting the most effective pacing strategy to complete the Comrades Marathon would optimise the performance of a runner and thereby lead to each being more likely to achieve their specific goal. Aims and Objectives The aim of this study was to analyse the race results of three years of the Comrades Marathon “up” runs, namely 2015, 2017 and 2019 and to compare the pacing profiles of the fastest through to the slowest male runners in the field. The objectives of this study were 1.) To analyse the race results of the Comrades Marathon “up” run to identify the pacing profiles adopted by the fastest male runners, through to the slower runners; 2.) To compare the pacing profile of the top 10 male runners in each year, relative to their most recent standard marathon pace. Methods The study utilised a retrospective design. The study sample included the Comrades Marathon race results over three years of consecutive “up” runs. Only male runners, irrespective of age, were included in the study. If runners featured in more than one race, only their fastest finish time was included in the sample for statistical analysis. Runners were excluded from the study if there were split (intermediate) times missing or if their data was incomplete in some way. In the second part of the study, runners in the top 10 were excluded if their most recent standard marathon time could not be established. Results A total of 22 199 male runners were included for data analysis. The data was divided into quartiles, based on finishing time. This resulted in four groups, separated by 1.67-hour intervals. The first group contained the smallest number of participants (n=503) which was only 2.3% of the field and the last quartile (group) contained the most runners at 50.3% of the field (n= 11181). There was a significant difference between groups one, two, and four in the pacing profile when speed through the race segments was normalised to the speed at which the first segment was run. This was also the case when speed through each segment was normalised to mean race pace (of the entire race). All four groups showed a parabolic pacing profile; specifically a reverse “J“-shaped, when race pace was normalised to both mean race speed and to speed of the first segment. Analysis of the elite runners (top 10) for each year, showed that these runners started at an average of 88% of their marathon pace and averaged 80-90% of their marathon pace throughout the race. The elite runners showed a positive pacing profile with moderate effect. Conclusion This study showed that there is no significant difference between the pacing profiles of the faster male runners versus slower male runners. Runners adopted a reverse “J”-shaped pacing profile when their pace at different points in the race was compared relative to their mean race pace, or when each segment was compared to the pace in the first segment of the race. This finding is similar to previous studies that found that the most efficient pacing profile in recreational ultramarathon and marathon runners is a parabolic shaped profile. The elite runners' Comrades Marathon started the race at an average of 88% of their marathon pace and maintained an average pace of 80-90% of their standard marathon pace, throughout the race.
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    A descriptive study of the prevalence of Acute Foot and Ankle complaints/injuries of adults attending a public sector secondary hospital orthopaedic clinic in South Africa over a 12-week period
    (2025) Dlamini, Njabulo Knowledge; D'alton, Caroline
    BACKGROUND: Orthopaedic trauma places a substantial cost burden on health systems around the world, and may also lead to mobility impairment, disability, and chronic pain in patients, especially when affecting the foot and ankle. The epidemiology of foot and ankle injuries has previously not been well reported in South Africa. In order to gain a greater understanding into the degree of health burden represented by conditions of the foot and ankle as well as the associated risk factors and types of injury, we aimed to describe and evaluate the patient population presenting at a public health hospital over a specified time period. Insights into the epidemiology specific to the South African context may aid health care resource planning and contribute to improved patient care. METHODS: A prospective, descriptive study was conducted to determine the prevalence, characteristics and risk factors of adults presenting to the orthopaedic acute clinic at Prince Mshiyeni Memorial Hospital with acute foot and ankle complaints/injuries between December 2022 to March 2023 (12-week period). Demographic (sex, age, height, weight, BMI) and clinical (type of injury, pain scores, management) data were collected and analysed using percentages, Mann-Whitney U Test, t test and Chi-square analysis. RESULTS During the 12-week period, 14% of the 615 lower limb cases were referred for Foot and Ankle injuries specifically. The cohort comprised 80 participants with an average age of 43 years with 64% (n=51) (being) female. Ankle fractures were the most common presenting injury (54%), with females more affected than males, 31 (61%) vs.12 (41%)) respectively. Males suffered more foot fractures than females, 12 (41%) vs. 5 (10%) respectively (p< 0.05). Foot fractures represented 21% of all foot and ankle injuries. Ankle sprains made up 15% of all injuries which interestingly was similar to that of midfoot sprains (15%). The highest number of injuries were noted within the age range 30-39 (34%) with no significant difference noted between sex and age presentation, but a significant difference was noted for mechanism of injury and sex (p< 0.001), no significant differences were noted for BMI between the sexes with a median of 25kg.m2 for both. Low energy fall was the most common mechanism of injury described affecting 66% of all participants and 74% (39) of females. Road traffic accidents (RTA) accounted for 21% (17) and direct trauma/assault 6% (5) of all mechanisms of injury. Fifty percent (40) of participants were managed conservatively by means of plaster of Paris, 40% (32) with plaster backslab, and 6% (5) admitted for surgical intervention. CONCLUSION: Foot and ankle pain is a prevalent problem which constitutes a high number of traumatic bony and soft tissue injuries. Within this cohort, more females presented with ankle fractures and males with foot fractures, with the 30-39-year age group most affected. Low energy fall mechanisms were most commonly reported within females, while males suffered more direct trauma and sports injury-related mechanisms. Only a small percentage of patients were admitted for surgery. The researchers recommend more epidemiological studies across major trauma centres with greater participant numbers and longer follow up to give a better scope into the full extent of the burden of foot and ankle pain/injuries in South Africa, and expand database registrations, hereby impacting policy making and budget allocation to improve patient care and outcomes
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    A dissection and angiographic study of anatomical variations in the anterior communicating artery complex in a South African sample
    (2024) Madolo, Mbalentle; Mpolokeng, Kentse; Gunston, Geney; More, Stuart
    The anterior communicating artery complex (ACAC) consists of the A1 and A2 segments of the anterior cerebral artery (ACA) and the anterior communicating artery (ACoA). The ACAC is said to be the most frequent site of aneurysms and anterior cerebral circulation variations. Clear correlation between cerebral arterial circulation variations and aneurysm development has been reported. Cerebrovascular diseases play a significant role in the causes of morbidity in South Africa. South African data in this area of research is currently lacking and thus more knowledge is needed. This study aims to report the prevalence of variations in the ACAC and their link to the prevalence of cerebral aneurysms. For the dissection portion of this study, a total of 68 (35 female and 33 male) adult formalin fixed brains were included. These brains were from the bodies that were previously dissected in the Department of Human Biology, University of Cape Town by the medical undergraduate and honours post-graduate students. For the ang
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    A mixed methods scoping review of gender and life stage as risk factors of injury-related mortality in the Western Cape, South Africa
    (2024) Voegt, Chelsey; Gibbon, Victoria; Dinkele Elizabeth
    Injury-related mortality is a growing public safety concern in South Africa, especially in the Western Cape Province. Several studies have identified gender and age as risk factors of injury related mortality, although there remains a scarcity of interstudy comparisons of these factors, and the underlying perceptions of causes linked to these. In this study, a scoping review of injury-related mortality from medicolegal death investigations in the Western Cape was conducted by screening online databases for research articles published between 2007 and 2021. Of the 11 articles, six were included in a quantitative analysis to quantify risk by gender and life stage. To assess conceptualisations of these risk factors in research, each article was evaluated using a thematic content analysis. Men were associated with a higher mortality risk for homicide (inclusive of sharp force and firearm causes), suicide, road traffic (and transport-related) deaths, and drowning. The likelihood of homicidal deaths in males (OR = 3.95; 95% CI [3.48 – 4.49]; p ≤ 0.001) was higher than all other causes of injury-related mortality (OR = 0.25; 95% CI [0.22 – 0.29]; p ≤ 0.001). For all causes of injury-related mortality, early adults (20 – 34 years) and middle-aged adults (35 – 49 years) accounted for the most deaths. Homicide was the most significant cause of mortality in early adults, adolescents and middle-aged adults, while road traffic deaths were the leading cause of mortality for infants and children and adults above 49 years of age. Qualitative results from the thematic content analysis suggest that the discourse of violence and injury in the literature differed by gender. Women were more commonly discussed with reference to vulnerability and victimhood. Contrastingly, men were portrayed with reference to culpability – regardless of whether they were victims or perpetrators of violence. Masculinity as a cause of violence, in the literature, was discussed relative to socio-economic conditions and cultural norms leading to risk-taking behaviours. Limited agency and lifestyle behaviours were described as primary causes of violence linked to life stage. Risk of injury in minors was attributed primarily to structural causes of violence, and cognitive reasoning and development linked to life stage. Overall, these results highlight gender-linked biases in forensic death reporting. Injury related deaths and homicides affected more males, yet males were primarily represented as perpetrators of violence. Given the drive to eradicate gender based-violence, this study emphasises the need to address structural causes of violence targeted at expressions of masculinity, social cohesion and identity in different life stages, and genders and the need for an intersectional approach to understanding medicolegal death investigations and injury-related mortality in the Western Cape and South Africa.
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    A morphometric study of the brain ventricles of patients diagnosed with Chronic Hydrocephalus at Groote Schuur Hospital
    (2024) Lichaba, Reagobaka; Mpolokeng, Kentse; Shamley Delva
    Hydrocephalus (HCP) is a cerebrospinal fluid condition of the central nervous system, which when it accumulates causes an increase in ventricular enlargement and raised intracranial pressure (ICP). Raised intracranial pressure in a fixed volume space is dangerous as it presses onto the brain parenchyma and the surrounding areas and may damage them. Ventricular enlargement is a radiological indicator of hydrocephalus and has been one of the features used to diagnose the condition, with the ICP measurement used to confirm the condition. However, measuring ICP is invasive and puts the brain at risk of bleeding and infections, making it necessary to use non-invasive methods of confirming the condition. This study aims to investigate the clinical features observed on the brain scans of patients with hydrocephalus and seeks to describe the unique shape of the frontal horns and use this shape as a noninvasive diagnostic marker. The study observed the brain magnetic resonance imaging and computed tomography scans of 150 patients who were suspected or known to have hydrocephalus from the Radiology Department at Groote Schuur Hospital. These scans were then divided into three groups, namely, the controls, and chronic and acute hydrocephalus groups. The clinical features commonly observed on the brain scans of patients with hydrocephalus were evaluated, their measurements taken, and their shapes recorded. These features were the Evans Index, temporal horn width, third ventricle width and shape, callosal angle, frontal horn shape, Sylvian fissure width and periventricular white matter changes. This morphometric data was then analysed to determine their relationship with hydrocephalus. Of the clinical features, the frontal horn shape has not been described in the literature. Therefore, it was described in this study, and its association with the measurement of ICP was assessed. There was a statistically significant difference in the morphometric data between the control and chronic HCP groups. In contrast, the difference in the data between the chronic and acute HCP groups was not statistically significant. In all three groups, there was a difference in size between the left and right sides, the right side had smaller measurements than the left. There was a significant difference in frontal horn shape between the chronic and acute HCP groups. Additionally, it was evident that there was a relationship between a specific shape of the frontal horn and the measurement of ICP. The morphometric data of the clinical features were consistent with the literature, except for the Sylvian fissure width. The data in this study showed that the accumulation of CSF occurred mostly on the left side in the clinical features that compared the sides, perhaps suggesting that the condition favoured the left side. The frontal horn shape was different in the chronic and acute HCP groups, it was described as quadrilateral and round, where the quadrilateral shape correlated with the low-moderate ICP, and the round shape correlated with the high ICP reading. Therefore, the frontal horn shape has the potential to be used in the clinical space as a non-invasive imaging marker when differentiating between chronic and acute HCP patients.
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    A new class of stem cells in South Africa: iPS cells
    (2013) Ballo, R; Greenberg, L J; Kidson, S H
    Created from adult rather than embryonic cells, induced pluripotent stem (iPS) cells represent a breakthrough in stem cell science, and their pioneers have been recognised with the 2012 Nobel Prize in Medicine. These cells offer new hope in the treatment of pathogenetic diseases, but there is still a way to go on the road to effective therapeutic applications.
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    A novel cough aerosol sampling device for sputum-scarce individuals with tuberculosis
    (2025) Ismail, Ra'eesah; Sivarasu, Sudesh; Dheda, Keertan
    Introduction In 2021, there were 10.6 million tuberculosis cases worldwide, with 1.6 million deaths. Bacterial infection occurs when aerosol droplets enter the respiratory tract and travel to the lungs, causing pulmonary disease. If untreated, the disease has a 50% mortality rate. TB diagnostics require a sputum sample to conduct tests to confirm the presence of Mtb but more than 15% of patients have difficulty producing this sample. A cough aerosol sampling system (CASS) can collect aerosol droplet samples for testing when sputum sampling is not possible. These systems rely on inertial impaction whereby particles are sorted based on their diameter. Thus, CASS also offers information regarding the infectivity of the patient based on their expelled aerosol sizes. This is because smaller respiratory droplets can travel to the smallest structures of the lung and are more likely to cause infection. CASS is a useful technology in field sampling in place of sputum sampling. However current systems are bulky, heavy and not optimised for field testing in resource limited settings – which this project aims to address. Methods & Materials The methodology included designing and developing a physical prototype of a novel miniaturised cough aerosol sampling system (Mini CASS). This device was designed in subsystems, namely the impaction cascade, pump system, mask part and casing. All subsystems followed a rapid prototyping approach characterised by multiple design iterations. The impaction cascade design was guided by Marple and Liu's methodology (1976). This included testing various impaction substrates. Furthermore, it was optimised by computational fluid dynamics. The entire design was evaluated against a set of predefined needs criteria developed through identification of inadequacies in current devices. Verification testing at the Medical Devices Lab (University of Cape Town) included confirmation of the aerosol size fractionation capacity of the cascade impactor. Validation testing was conducted at the Centre for Lung Infection and Immunity (Groote Schuur Hospital) to confirm the ability of Mini CASS to collect culturable bioaerosols (M. smegmatis). Results & Discussion A partially disposable, portable and miniaturised CASS was built with a weight and size of less than 1 kg & 40 cm2 respectively. Results of in-silico and verification testing have confirmed the ability of the device to perform size fractionation with atleast a 30% efficiency per stage. The device successfully collected nebulised M. smegmatis & M. bovis. Culture confirmation of the bacteria proves this as a viable impactor with atleast 3 colony forming units on each stage, comparable to current CASS systems. Conclusion The final Mini CASS prototype exhibited favourable characteristics of being lightweight and easily portable. It fared well in tests conducted to assess viability, proving its capability to collect bioaerosol samples for culture from coughing. It exhibited the ability to fractionate aerosol samples to provide a semi-quantitative measure of infectiousness with known particle sizes and efficiencies. This proof-of-concept device shows CASS technology can be optimised for use in the clinical setting, thereby enabling it to become a more powerful sampling and research tool. The lightweight, easy to use technology has the potential for use at home or temporary sampling sites.
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    A pilot study to identify links between genetic variation and shoulder pain and dysfunction after breast cancer radiotherapy
    (2021) McLarty, Callum; Shamley, ‪Delva; September, Alison
    Introduction – Treatment for breast cancer is associated with a risk of chronic shoulder and upper limb morbidity in up to 30% of patients. There is currently no consensus for the possible reason for this often repeated finding in the literature. Previous research has suggested that development of fibrotic tissue in response to cancer treatments such as surgery and radiotherapy could be an underlying cause of musculoskeletal dysfunction and pain. This study investigated if any genetic variants in several key fibrosis-modulating genes could be shown to be associated with risk of upper limb musculoskeletal dysfunction and pain in breast cancer survivors. Participants and Methods – A cross sectional study design was employed, using a candidate gene approach. A total of 326 South African breast cancer survivors were recruited from a tertiary hospital in the Western Cape (343 total, minus 17 samples with insufficient data collected). Each participant was scored for symptom severity using the shoulder pain and disability index (SPADI) questionnaire. Participants were then grouped for symptom severity using low, med or high SPADI scores. The low SPADI group served as controls (controls n=273, cases n=70). Participants were invited to donate a blood sample from which DNA was extracted. Each DNA sample was genotyped at seven polymorphic sites; three in TGF-ß, two in ATM, one in SOD2 and one in XRCC1, using PCR technologies and TaqMan allelic-discrimination probes. The resultant genotypes were analysed using multivariate analysis, including inferred haplotype analysis to search for association to shoulder pain and morbidity after treatment. A logistic regression analysis was also performed to investigate the association between SPADI score and age of participant. Results – When participant age was compared with symptom severity, it was found that younger participants were more likely to have moderate-to-severe symptoms than older participants. There was a significant difference in the minor allele frequencies between case and control groups for the rs4880 (C>T, SOD2) polymorphism. The T allele was present more in the case group than in controls, with minor allele frequencies of 0.67 vs 0.55 respectively. No other independent associations were noted for any of the remainder variants tested. When haplotypes were inferred for genes SOD2 and ATM, combinations between the rare alleles at rs4880 and rs1800058 (C>T, ATM) were associated (F=4.35, pT and ATM rs1800058 is recommended for further study, in addition to the rs4880 polymorphism in SOD2. These novel results are suggesting that there may be an association between fibrotic genes and the development of upper limb sequelae after treatment for breast cancer. A larger case-control study would be required to validate and explore these findings.
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    A sleep behaviour intervention to improve cardiometabolic health in adults with overweight and obesity
    (2020) Henst, Rob HP; Rae, Dale E; Roden, Laura C
    Rob Henricus Petrus Henst was born on the 12th of March in Schaijk, the Netherlands. He graduated from pre-vocational secondary education (VMBO) in 2005 and continued to study process and laboratory technology at an intermediate vocational educational (MBO) institution. In 2009, Rob started with a Bachelor of Science degree, majoring in Life Science with a minor in Exercise Science. For his undergraduate thesis in 2012, he moved to South Africa where he was introduced to chronobiology in exercise science. In 2013, Rob continued to study in South Africa for his Master of Science (Exercise Science) degree and published his first peer-reviewed article in the Journal of Biological Rhythms. He then developed an interest in sleep and cardiometabolic health, specifically in the context of public health. In 2015, these interests were combined and lead to his current PhD thesis on a sleep behaviour intervention for the betterment of cardiometabolic health. In this year, he also co-founded the business unit Sleep Science within the Sports Science Institute of South Africa to help individuals sleep better. In 2019, Rob moved back to the Netherlands to write the final pages of his PhD thesis.
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    A structured light solution for detecting scapular dyskinesis
    (2018) Verster, Jaco; Gray, Janine; Sivarasu, Sudesh; Mutsvangwa, Tinashe
    Scapular dyskinesis is a common occurrence in overhead athletes, i.e. athletes who participate in any sport where the upper arm and shoulder is used above the athlete’s head. However, no consensus has been reached on how to evaluate scapular dyskinesis quantitatively. In this thesis, we developed a measuring tool that can be used to evaluate certain key clinical parameters specific to scapular dyskinesis. The tool employs a 3D structured light computer vision approach to create a surface map of the soft-tissue across the scapula. This surface map is then analysed using surface curvature analysis techniques to identify the key clinical parameters associated with scapular dyskinesis. The main advantage of this method is that it provides a measurement tool that may facilitate future quantitative analysis of these key parameters. This may aid with diagnosis and monitoring of the condition by allowing measurement data to be collected both before and after treatment and rehabilitation. We expect that this tool will make the monitoring of treatment effectiveness easier while contributing to diagnostic computer vision.
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    A study comparing the effects of vincristine with those of ionizing radiation on the root meristem of Vicia faba
    (1972) Haddad, Dawne Merle
    Vincristine and vinblastine, two closely related alkaloids are extracted from the Madagaskar Periwinkle, Vinca rosea Linn. They have been shown to be effective oncolytic agents and cause arrest of mitosis at the metaphase stage, similar to that of colchicine andcolcimid. Clinically, vincristine has been found to produce a complete remission in patients with acute leukaemia. Tumour regression in patients with Hodgkin's disease, lymphosarcoma and certain childhood solid tumours have also been reported.
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    A study of the response of the root meristem of maize to fractionated and protracted doses of ionizing radiation
    (1971) Hering, Egbert Raymond
    Vicia faba and investigating the effects of ionizing radiation on its root system. In particular, species such as Tradescantia, Pisum, Allium and Mordeum vulgare have been extensively studied. Nevertheless an ever-increasing number of workers have used Vicia faba for explaining the basic problems of radio biology. One of the reasons is the small number of large chromosomes contained in the root meristem cells, which are particularly conducive to simple cytological analysis. The seedlings also have other attractive features.
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    A study on the role of oxidative stress and protein kinase signalling in hyperglycaemia induced cardiac remodelling
    (2023) Amtha, Nikhil; Gwanyanya, Asfree
    Background Almost one-third of all deaths in patients with uncontrolled diabetes mellitus and hyperglycaemia are due to cardiovascular diseases. Chronic exposure of the heart to hyperglycaemia leads to a maladaptation called pathological cardiac remodelling and occurs via oxidative stress due to excess production of reactive oxygen species (ROS). In the heart, ROS modulates cardiac differentiation, cardiomyocyte proliferation, and myocardial tissue growth via ROS-sensitive protein kinases such as the mitogen-activated protein kinase (MAPK). Although there are several different MAPKs, the p38 MAPKs are involved in cardiogenesis and implicated in stimulating myocyte apoptosis, hypertrophy, or even antiapoptotic effects. As such, the role of p38 MAPKs in diabetic cardiac remodelling, especially during cardiac development, remains unclear. This study aims to elucidate the effect of hyperglycaemia on the p38 MAPK signalling pathway in a cardiac developmental model. Methods Pluripotent mouse embryonic stem cells (mESCs) were differentiated in vitro into cardiaclike pulsatile embryoid bodies (EBs) using the hanging drop method. Once pulsatile, EBs were further cultured for 72 hours in either baseline (25mM) or high glucose (50mM) media or with the pro-oxidant hydrogen peroxide (100μM). Changes in EB morphology and beating characteristics were observed using transmitted light microscopy. Immunocytochemistry and fluorescence microscopy imaging was used to detect changes in biomarkers. The nuclear uptake of propidium iodide (PI) was used to evaluate cell viability, whereas the 5-ethynyl-1- deoxyuridine (EdU) assay was used to determine cell proliferation. Western blot was used to analyse protein expression. Results Treatment with hydrogen peroxide stunted EB growth and decreased EB diameter, consistent with the presence of oxidative stress. High glucose increased the number of pyknotic-like nuclei and reduced the number of EdU-positive nuclei. Furthermore, hyperglycaemia elevated the expression of phosphorylated p38 MAPK, without altering total p38 MAPK expression levels. Inhibition of p38 MAPK by SB203580 in high glucose attenuated the increased number of pyknotic-like nuclei in high glucose and enhanced the number of EdUpositive nuclei compared to high glucose alone. High glucose also reduced the expression of the mitochondrial fusion regulatory protein, optic atrophy-1 (OPA1), with the inhibition of p38MAPK in high glucose attenuating this effect. Conclusion Hyperglycaemia induced pyknotic-like phenomenon, suppressed the proliferation, and reduced mitochondrial fusion protein machinery of mESC-derived cardiac-like cells. These effects were likely triggered by a mild form of oxidative stress and involved the activation of p38 MAPK. The findings provide insights into the mechanisms underlying diabetic developmental cardiac remodelling and identify p38MAPKs as a potential therapeutic target.
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    A study to examine the validity and reliability of a selected group of physical fitness tests within a primary school setting
    (2025) Buck, Robin; Lambert, Michael
    Purpose: This study represents an effort to provide an evidence-based approach to selecting field-based fitness measures for children and youth for inclusion in a test battery to be used within the school setting. The approach used by the author considers the following criteria to determine which youth fitness test items would be most appropriate for inclusion: (1) the strength of the fitness tests' association with health markers in youth, (2) the fitness tests integrity (validity and reliability), (3) the relative feasibility of the test administration in the field and (4) the measurement error of the fitness test. This study aims to identify valid and reliable physical fitness tests with low measurement errors for use in South African schools Method: A literature review was performed to determine the predictive and criterion validity of physical fitness tests in children. Tests with strong predictive evidence and good criterion validity were selected for further reliability testing. A group of 290 male and female children aged 6 to 13 years performed a physical fitness testing protocol three times within a 7-day period. The typical error of measurement (TE), coefficient of variation (CVTE) and smallest worthwhile change (SWC) were calculated for each sex and age group (grade). Changes in measurement were categorised as small, medium or large based on effect sizes. Results: The 20m shuttle run (SRT), hand grip strength (HGS), standing long jump (SLJ), body mass index (BMI), and waist circumference (WC) tests demonstrate strong predictive evidence and good criterion validity. Typical error for the 20mSRT was 0.9 stages. Small changes in 20mSRT (0.4 stages) are challenging for the test to detect. Medium (1.0 stages) and large (1.9 stages) changes in the 20mSRT are more interpretable as they exceed the “noise” (TE) of the measurement. Small (0.6 kg/m2), medium (1.6 kg/m2) and large (2.5 kg/m2) changes in BMI are all larger than the TE (0.2 kg/m2). The BMI test has a ‘good' ability to detect small, medium and large changes. TE for HGS was 1.3 kg. Small changes in HGS (1.3kg) are difficult for the HGS test to detect. Medium (3.3kg) and large (5.3kg) changes in HGS are more interpretable as they exceed the “noise” (TE) of the measurement. The WC test has a ‘good' ability to detect small (1.5 cm), medium (3.8 cm) and large (6.1 cm) changes as they are larger than the TE (1.5 cm). TE for SLJ was 8.8 cm. Small changes in SLJ (5.4 cm) are difficult for the SLJ test to detect. Medium (13.5 cm) and large (21.5 cm) changes in SLJ are more interpretable as they exceed the “noise” (TE) of the measurement. Conclusion: The field-based physical fitness tests that demonstrated strong predictive validity and good criterion validity from the literature and low measurement error from the reliability data are HGS, SLJ, BMI, WC and 20mSRT. These fitness tests could be included in a battery of tests for implementation within the school setting. Researchers and practitioners can use the SWC and TE as guidelines to set targets when determining the extent to which performance changes in these fitness tests are practically significant.
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    A vector based approach for high frequency prospective correction of rigid body motion in Magnetic Resonance Imaging (MRI)
    (2019) Van Niekerk, Adam Marthinus Johannes; Meintjes, Ernesta; van der Kouwe, Andre
    Magnetic Resonance Imaging (MRI) is remarkable in that it is possible to obtain image resolutions much smaller than the wavelength of the radiated signal. This is achieved through the use of specialised gradient coils that linearly manipulate the magnitude of the magnetic field within the imaging volume. The instantaneous signal received from the subject represents a periodically varying map based on the duration and magnitude (moment) of the previously applied gradient fields. Representing an object as the sum of periodic maps is difficult and as a result many unique gradient moments are required to form an image. When the subject moves the periodic maps are no longer coherent and the constructive/destructive interference becomes invalid. The artefacts are dependent on how and when motion occurred, and manifest as ghosting, ringing and blurring of the image. This thesis describes a novel approach to measuring and correcting for motion as the data are acquired. A small device was constructed that combines observations from a magnetometer (static magnetic field [z]) and an accelerometer (earth’s gravitational field [y]) with an angular rate sensor to determine its orientation with respect to the imaging coordinate frame (VectOrient). It was precise enough to track the subject’s heart beat and breathing and accurate to within one degree. A gradient field probe was then designed for position encoding. The probe measured the rate of change of the gradient magnetic fields using three mutually orthogonal pickup coils. Assuming linear gradients and using Maxwell’s equations, with negligible rates of change of curl and divergence, it was possible to accurately model the three dimensional vector fields that the gradients produce, eliminating the need for a laborious manual calibration. Sub-microsecond synchronisation was achieved by detecting radio frequency pulses in the imaging sequence with a small resonant circuit. This combined with a 2.4 GHz radio link enabled the probe to be wireless. Finally, the pickup coil observations were combined with the vector based orientation estimates and the gradient field model to achieve efficient multidimensional position, orientation and inter-gradient-delay encoding with a 880 µs pulse sequence insert. The Wireless Radio frequency triggered Acquisition Device (WRAD) tracks involuntary and deliberate subject motion, improving image quality without scanner specific calibration.
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    A wait-list controlled evaluation of the Qhubeka bicycle on an adolescent's physiology, executive function, and school performance
    (2021) Mcdonald, Reece Brian; Swart, Jeroen; Holliday, Wendy
    Learner mobility and active school travel (AST) has been proposed to improve school attendance and academic performance. In South Africa, approximately 86% of learners have been reported as walking to and from school. AST in Africa is becoming less common in urban areas, and this may be a contributing factor to the increased risk and frequency of noncommunicable diseases due to decreased physical activity. The aim of this wait-list controlled evaluation was to assess the physiological and cognitive changes of access to a bicycle versus walking on adolescents. Specifically, changes adolescent's physical activity levels and executive function in a South African low-income community. Two schools were recruited, with the evaluation school receiving bicycles and the control a school who were yet to receive bicycles. Significant differences were observed across the physiological and executive function assessments. Most notably in the executive function tests, the evaluation group showed significant time to completion decreases across all three tests (N-Back, Arrow Flanker, WCST: p< 0.001). The results from this study are significant, as they are the first to assess anthropometric, physiological and executive function in South African adolescents from low-socioeconomic regions. It is evident that there are potential improvements in working memory, inhibition and shifting due to cycling as a mode of AST or during leisuretime. Further research needs to determine the specific mechanisms associated with these improvements.
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    Adolescents’ Perspectives on the Drivers of Obesity Using a Group Model Building Approach: A South African Perspective
    (2022-02-14) Hendricks, Gaironeesa; Savona, Natalie; Aguiar, Anaely; Alaba, Olufunke; Booley, Sharmilah; Malczyk, Sonia; Nwosu, Emmanuel; Knai, Cecile; Rutter, Harry; Klepp, Knut-Inge; Harbron, Janetta
    Overweight and obesity increase the risk of a range of poor physiological and psychosocial health outcomes. Previous work with well-defined cohorts has explored the determinants of obesity and employed various methods and measures; however, less is known on the broader societal drivers, beyond individual-level influences, using a systems framework with adolescents. The aim of this study was to explore the drivers of obesity from adolescents’ perspectives using a systems approach through group model building in four South African schools. Group model building was used to generate 4 causal loop diagrams with 62 adolescents aged 16–18 years. These maps were merged into one final map, and the main themes were identified: (i) physical activity and social media use; (ii) physical activity, health-related morbidity, and socio-economic status; (iii) accessibility of unhealthy food and energy intake/body weight; (iv) psychological distress, body weight, and weight-related bullying; and (v) parental involvement and unhealthy food intake. Our study identified meaningful policy-relevant insights into the drivers of adolescent obesity, as described by the young people themselves in a South African context. This approach, both the process of construction and the final visualization, provides a basis for taking a novel approach to prevention and intervention recommendations for adolescent obesity.
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    Adult age-at-death estimation using the pulp/tooth area ratio (PAR) method: a South African validation study using periapical radiography and stereomicroscopy
    (2024) Kotze, Daniël; Gibbon, Victoria; Mole, Calvin
    Conventional skeletal age-at-death estimation methods employed for South African adults are deficient, facing several limitations. Dental ageing techniques remain under-researched for the population. In this study, I aimed to evaluate the applicability of the pulp/tooth area ratio (PAR) ageing method when applied to maxillary canines from a South African cadaveric sample. I explored the utility of under-researched methodological approaches for the method: mesiodistal radiographs, stereomicroscopic tooth section images and PARs excluding the enamel area. To maximise sample size, only maxillary canines were considered, which demonstrate several research advantages (e.g. relatively long functional survival and high accuracy rates). Following extraction, 52 adult teeth were radiographed, sectioned and analysed using stereomicroscopy. Labiolingual and mesiodistal radiographs and labiolingual stereomicroscopic tooth section images were captured and analysed using ImageJ to obtain PARs. Age estimation linear regression models were developed for ratios obtained from each image type, including and excluding the enamel area. Models were compared for performance and accuracy using best subsets regression and cross-validation analyses. The accuracy of international standards was also assessed using the study sample. The PAR method showed promising results. It demonstrated excellent observer reproducibility and sex-independence. Sample-specific models derived from tooth section images had the best performance and accuracy, obtaining cross-validation mean absolute errors (MAEs) and standard error of the estimates (SEEs) of approximately 7 - 8 years and 10 - 11 years, respectively. Labiolingual radiographic models (MAEs = 10 years; SEEs = 12 years) showed better performance and accuracy than mesiodistal radiographic models (MAEs = 12 years; SEEs = 16 2 years). Models excluding the enamel area performed better, producing slightly better cross validation error values. Standard PAR models performed relatively poorly and were inappropriate for the study sample. This research suggests that the PAR method is a suitable technique to complement and inform standard adult skeletal age analyses in South Africa. The labiolingual radiographic approach is most practical as it is relatively accurate, minimally invasive and efficient. This study contributes knowledge to the limited pool of data on dental ageing techniques for South African adults. It informs practitioners of ideal/optimal methodological approaches for the PAR method using maxillary canines.
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    Open Access
    Aetiology of fatigue during maximal and supramaximal exercise
    (2003) Nobbs, Les; Noakes, Tim; Gibson, A St Clair; Rauch, L H
    The aim of this thesis was to investigate the extent of peripheral and central components in the development of fatigue during maximal exercise. Fatigue during maximal and supramaximal excercise has traditionally been modelled from the peripheral context of an inadequate capacity to supply metabolic substrate to the contracting muscles to meet the increased energy demand.