Browsing by Subject "Human Biology"

Now showing 1 - 20 of 94
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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 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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    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.
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    An investigation into variations in the venous drainage pattern in brains of adolescents and adults
    (2020) du Toit, Francesca; Louw, Graham J
    It is well established that the brain changes dramatically in appearance during gestation and even after birth. Due to the multi-channelled origins and the number of developmental options, the adult venous system is characterised by a higher incidence of anatomical variations than the arterial system. Limited information is available on anatomical variation of the complete cerebral venous system. It is important to have an understanding of the usual drainage pattern the cerebral venous system and its anatomical variations to provide a foundation for future studies on anomalous venous structures. The extent to which fetal drainage patterns persist postnatally has yet to be established. The goal of the current study was to accurately describe the cerebral venous drainage patterns, including persistence of fetal drainage patterns in children, adolescents and adults in order to understand anatomical variations and the clinical impact during cerebrovascular interventions. For the current study 302 magnetic resonance images with contrast medium from the Groote Schuur and Red Cross Children's War Memorial Hospitals were retrospectively reviewed. The volumes of the dural venous sinuses were traced using a novel approach developed for the study. The approach included constructing 3D models of the dural venous sinuses and using the tracings for statistical and morphological analyses. No images of children met the inclusion criteria and therefore further analyses of the subset was not possible. Statistical analyses were performed to determine if there are any associations between venous sinus volume and sex, age, cerebral dominance and/or variations. Significant differences were noted for sex, dominance and variations of the cerebral venous system. The confluence of sinuses (CS) showed the most abundant number of variations. Although many studies and classifications have been made regarding the variations of these structures, there is a lack of a comprehensive classification that includes all variations. The goal of the current study was to determine the anatomical variations more comprehensively particularly at the level of the superior sagittal sinus (SSS) and confluence of sinuses. The study improved on the current literature by using contrast enhanced images as opposed to nonenhanced images or results obtained at autopsy. It is also the first study to establish a tracing protocol for venous volume to determine cerebral dominance and describe variations of the dural venous sinuses.
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    Anabolic-androgenic steroids : knowledge, attitudes, ethical dilemmas and review for primary care physicians
    (2002) Ebrahim, F A; Lambert, Mike; Schwellnus, Martin
    Includes bibliographical references.
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    The anti-cancer activity of a novel palladacycle, BTC2, in oestrogen receptor positive and triple negative breast cancers
    (2017) Irene, Ikponmwosa; Prince, Sharon; Kimani, Serah
    Breast cancer remains the leading cause of cancer death among women worldwide. This is in part due to late diagnosis, high recurrence rate and the development of drug resistance. Indeed, even though oestrogen receptor-positive breast cancers are known to respond to hormonal therapy, drug resistance is a common occurrence. Furthermore, triple negative breast cancers lack a specific therapeutic target, which has led to poor treatment outcomes. Hence, there is a critical need for new therapeutic approaches. Our laboratory previously identified a novel palladium-based compound, AJ-5, that exhibit potent anti-cancer activity in triple negative and oestrogen receptor-positive breast cancer cells. However, AJ-5 is poorly soluble, therefore, a series of water soluble AJ-5-based compounds were synthesized. The aim of this study was to test and characterise the anti-cancer activity of one of these AJ-5 analogues, BTC2, in triple negative (MDA-MB-231) and oestrogen receptor-positive (MCF7) breast cancer cell lines. Cytotoxicity assays were performed and BTC2 was shown to inhibit the proliferative rates of breast cancer cells with calculated IC50 values of 0.49μM in MCF7 cells and 0.58μM in MDA-MB-231 cells. BTC2 did not display considerable selectivity to breast cancer cells as the calculated IC50 value for the normal fibroblast cell line (FG0) was found to be 0.85μM and thus the selectivity index was less than 2 in both cell lines. Clonogenic assays were performed and BTC2 was shown to inhibit the long term (10 to 21 days) survival of MCF7 and MDA-MB-231 cells as it reduced their colony forming ability. Western blot analyses and immunofluorescence with an antibody to ƴH2AX, a robust marker of DNA double strand breaks, indicated that BTC2 acts by inducing DNA damage as the levels of this protein increased in drug treated cells. Light microscopy revealed that BTC2 induced morphological features of apoptosis (membrane blebbing and cell shrinkage) and autophagy (vacuoles reminiscent of autophagosomes). To further characterise the molecular mechanism underpinning the cytotoxic effects of BTC2, western blotting was performed with antibodies against key protein markers of stress signalling, cell cycle, apoptosis and autophagy. The results indicated that BTC2 activated the p38 MAP kinase signalling pathway and the p53 response in MCF7 cells. It is worth noting that MDA-MB-231 cells have a mutant p53 but that the p53 target protein, p21, was upregulated in both MCF7 and MDA-MB-231 cells. This suggests that p21 is regulated by a p53-independent mechanism in the MDA-MB-231 cells. BTC2 was shown to induce apoptosis and autophagy in both breast cancer cell lines as demonstrated by increased levels of cleaved PARP and LC3-II respectively. Apoptosis was confirmed by Annexin V-FITC/ propidium iodide double staining using flow cytometry. Taken together, data from this study suggest that BTC2 represents a promising anti-cancer drug for the treatment of triple negative and oestrogen receptor-positive breast cancer cells.
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    Application and development of indirect measures of free-living energy expenditure
    (2004) Keytel, Lara; Lambert, Vicki
    The aims of this thesis were to explore the accuracy in measuring free-living total daily energy expenditure (TDEE), by examining existing indirect measures of energy expenditure (EE) measurement and further, developing new techniques, for improved accuracy and application, in population-based studies. In a number of the studies, the research focus is the heart rate (HR) monitoring technique, for TDEE estimation as a result of its low cost and ease of implementation in large population-based studies. This thesis represents a progression from the application of the HR monitoring technique for estimating EE in response to training, or as a means to validate a physical activity recall instrument. However, what is highlighted are the limitations of the existing methodology for estimated TDEE in this way. Therefore, this thesis introduces a novel concept in the HR monitoring technique, incorporating group-based EE equations, and further, by including the effects of the previous minutes HR response on the estimation of EE from HR. Finally, this thesis validates these modifications, using a respiration chamber, purpose-built as a part of this dissertation. It should be noted, however, that in some instances, the thesis was constrained by opportunistic sampling, or the fact that in the case of Chapter 4, the study sample was part of a larger study designed for another purpose. Nevertheless, the outcomes of this research, in particular, the group-based HR-EE prediction equations, have important implications for large population-based epidemiological research concerning physical activity dose-response. Bibliography: p. 227-253.
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    The application of clinical gait analysis to running injuries
    (2005) Arendse, Regan Emile; Schwellnus, Martin; Gibson, Alan St Clair
    Clinical evaluation of the injured runner requires identification and correction of the multiple factors commonly implicated in running injury. Effective management of running injuries requires that the concerned health professional identify all implicated factors. In this regard it is essential that the relationship between running style and injury he determined, because if there is an association between the gait analysis variables descriptive of running style and injury, these would be important in the management of the injured runner. The Gait Analysis Laboratory at the Sports Science institute of South Africa and the University of Cape Town with its three-dimensional Vicon 370 motion analysis system and Advanced Medical Technology industry® strain gauge force platform is appropriate for collecting data to study running style. These data include the movement patterns and estimated mechanical power and work required to effect the observed movement of the ankle and knee. The forces applied by the supporting surfaces on the runners were collected. The data captured with the Workstation® programme (Oxford Metric, Oxford, England), was processed with GaitLab® (Kiboho Publishers, Cape Town, South Africa), collated in Excel ® (Microsoft Corporation, Redmond, USA) and statistically analysed (StatSoft, Inc. (2000). STATISTICA for Windows [Computer program manual]. Tulsa, OK, USA). In this thesis a series of studies are presented with the aim of determining the relevance of running style to the assessment of the injured runner and the conventional treatment methods used to treat common running injuries.
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    An assessment of the health status by non-specific stress indicators in early farming populations from central and southern Africa
    (2006) Dlamini, Nonhlanhla; Morris, Alan
    The adoption of an agricultural lifestyle had profound implications for nutritional ecology, health and behaviour of human populations. The goal of this project was to generate information about the health status and disease patterns of early farming populations from central and southern Africa. Skeletal material was obtained from various 'Iron Age' sites in South Africa, Ingombe Ilede from Zambia, and Sanga and Katoto from the Democratic Republic of Congo. Palaeopathological analyses was done through the examination of non-specific stress indicators that included cribra orbitalia/porotic hyperostosis, Harris lines, linear enamel hypoplasias, subperiosteal bone lesions and dental diseases. The evidence from palaeopathology indicated that the environments played a major role in causing differences observed at micro-scale level. It is suggested that the health problems of these agricultural peoples are a result of their sedentary lifestyle and aggregation, which promoted maintenance and spread of infectious diseases; as well as high carbohydrate diets and dependence on a few main foodstuffs that affected their iron levels. The individuals from the forest region were less healthy than those in the dry or wet savanna zones. Also, the impact of the stress experienced by these societies was not sufficient to cause stunted growth and thus did not affect their terminal heights. The complex relationship between the environment, socio-cultural factors and biology has shown that subsistence economy only influences a fraction of human behaviour, health and well being. The results of this study argue that generalisations about prehistoric farming peoples cannot be made, until further research work is done.
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    Best medical care practices in sport: investigating the barriers to the implementation in the developing countries. Uganda as a case study
    (2020) Lubega, Samuelsaul; Lambert, Mike
    The dissertation consists of four separate studies that have focused on different aspects of the relationship between the management of sports related injuries and utilisation of best practices before sports, during sports and after sports-related injuries. Background: Participation in sports has an associated risk of injury which is defined by the type of sport and level of participation. Any injury affects the athletes‘ health status. To mitigate this risk, international sporting organizations provide guidelines, and mandates the proper evaluation and care for athletes before, during and after training or participation in competition. Despite the availability of guidelines describing best medical care practices for managing athletes, inappropriate management practices are reported globally. The barriers to best medical practice vary. While these barriers have been investigated in a variety of sports in developed countries, similar investigations have not been extensively conducted in developing countries, where the demands are different. Therefore, the overall aim of this thesis was to explore barriers to best medical practices in a variety of sports in Uganda. Methodology: The research was conducted as four studies. The first study used a descriptive case study approach. The data were collected on a sample of injured athletes (n=75) from four sports in Uganda (football/soccer, athletics, basketball and rugby) to describe the medical care practices of the sports resource providers. The current prevention, emergency care, intermediate treatment, rehabilitation services and return-to-sports strategies were all documented in a period of six months. The gaps in best practices were observed, and further investigated in the next three studies. Firstly, a validated questionnaire was used to establish the level of knowledge and practices of various components/themes of athletes‘ well-being and best practices among the stakeholders. Secondly, the current standards of the sports arenas and medical and high-performance facilities were examined using a validated checklist. The last study was a semi-structured interview which assessed the available national health care policies to support sports best practice strategies in Uganda Findings: The overall results of the first study showed there was a significant lack of compliance to best medical care practices in all the phases of athletes‘ health care. The barriers to best practice were confirmed as: (i) the lack of adequate knowledge and awareness on various best practice strategies, (ii) the sports and health facilities were below the required standards and, (iii) there were no national health sports care policies to support and facilitate the implementation of best practices in Uganda. Conclusion: (i) A holistic approach may be required to address the best medical care practice barriers in Uganda to improve on the health and safety of athletes. (ii) The knowledge of stakeholders should be improved and awareness created about best medical practices in sports in Uganda. (iii) There is a critical need to develop a national sports health care policy. (iv) The facilities for sports and health care of athletes urgently need improvement and supported.
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    Black River Cemetery: An anthropological study of the human remains exhumed from a historic Cape Town burial ground
    (2020) Pütter, Christie; Friedling, Jacqui; Patrick, Mary
    The Black River Cemetery, located in modern day Athlone (a suburb of Cape Town), was open for burials from 1867 - 1951, serving three Anglican Churches. The recent (2017) excavation of the historic site allowed for the analysis of the exhumed skeletal remains. The outcome of the skeletal analysis is valuable as the lives documented on the skeleton of a past group of people can write the story of individuals and communities that may have otherwise been omitted from the history books. The aim of this study is to describe demography, lifestyle and disease for a group of people living at the Cape between the 18th and early 20th centuries. The excavation of the cemetery yielded 1,305 graves of which 1,050 contained skeletal remains. Skeletal preservation was varied due to taphonomic influences, but overall it was poor with high fragmentation and taphonomic loss of skeletal material. The skeletal analysis performed utilised several well-established methodologies used in bioarchaeological and forensic anthropological disciplines and produced a body of information encompassing the demographics for this historic skeletal sample. Historical research on the Colonial Cape, coupled with the Black River Cemetery history and burial registers was employed to provide the context to the results of the skeletal analysis. The historic research suggests that the community and people buried there were most likely hardworking people of the poorer communities at the Cape in the 18th and 19th century with a division of labour between men and women. In the period of time that the cemetery was receiving burials, multiple social, political and economic changes occurred including; the bubonic (black) plague, Spanish influenza epidemic, the Boer War, the First World War and the Diamond Rush. It also saw the beginnings of racially segregated living and forced relocations. This backdrop provides an interesting landscape on which to view the skeletal analysis. The data analyses showed that the mortality profiles were skewed from the normal profiles determined by Weiss (1973). The sex ratio was skewed toward males indicating a greater mortality risk for men while the age mortality profiles showed a higher child and juvenile mortality and lower old adult mortality than is typically expected in a cemetery assemblage. This is an indicator of the effects of the epidemics and other factors reducing survivability of individuals. The low frequencies of periosteal reactions also may point to the poor survival capability as individuals may have succumbed to infections before the effect would be exhibited on the skeletal material. Pathological and stress indicators also show a sexually dimorphic trend with males exhibiting greater frequencies of degenerative joint disease, fractures, osteophytic growths and rates of dental attrition. Stature analysis showed a sexually homogenous group of people suggesting a lower health status and likely malnourishment or undernutrition. The social environment in which people lived likely contributed to a weakened immune system, and the generally poor health status of the people. The experience of the people living in Black River and the surrounding areas appears to be one of hard, repetitive labour and nutritional stress within an everchanging urban setting.
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    Bone health and physical activity through the various life stages
    (2003) Micklesfield, Lisa; Lambert, Vicki
    The aims of this thesis were to investigate the interaction between physical activity and bone health through various life stages, in order to better understand the determinants of adult bone mass and consequently, osteoporosis. All the studies have been carried out on the various ethnic groups that make up the population of South Africa, with widely divergent economic and sociocultural experiences, and therefore provide us with insight into determinants of bone health within the South African context. In this dissertation, we will explore the relationship and interactions between physical activity, and other lifestyle, physiological and demographic factors, on BMD and bone QUS parameters in the South African population. What sets this thesis apart is that we consider groups that are largely unstudied, groups undergoing demographic and epidemiological transitions, and even groups for whom physical activity may no longer provide protection for bone health.
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    Characterisation and functional analysis of the chicken microphthalmia gene
    (2002) Pinder, Karen Elizabeth; Kidson, Sue
    Despite the fact that the chicken embryo is a model system for developmental biologists, comparatively little is known about the regulation of avian melanogenesis. There has only been one report of the characterisation of the chicken tyrosinase gene promoter, and only one full-length chicken microphthalmia cDNA (cmi9) has been identified to date.
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    Clinical and imaging features of the lumbar spine in elite male schoolboy cricketers : the effect of a pre-season lumbar stabilisation intervention
    (2008) Aginsky, Kerith Dana; Derman, Wayne; Gray, J
    Current evidence indicates that schoolboy cricketers are at a high risk of injury to the lumbar spine. This is particularly relevant in the case of fast bowlers who bowl with a high degree of shoulder counter-rotation. There, however, is a lack of evidence in the literature with respect to injury research of all cricketing disciplines, as fast bowlers receive the most attention. After reviewing the literature it was evident that the effect of a cricket-specific lumbar stabilisation exercise intervention in an attempt to reduce lower back pain and alter other physiological variables, had never been studied. Previous interventions in cricketers have focused only on fast bowlers in an attempt to decrease the degree of shoulder counter-rotation. However, these studies either took two years to observe a decrease or were unsuccessful.
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    A control system approach to subject specific prospective respiratory motion correction in cardiac MRI
    (2012) Burger, Ian H; Meintjes, Ernesta
    Respiratory motion of the heart is a problem for high-resolution cardiac MRI. Diaphragmatic navigator gating with a 5mm acceptance window is most commonly used to address this but has an inherently low respiratory efficiency that is further compromised by respiratory drift. A novel method is presented that uses data from multiple navigators prior to the imaging segment as input for a control system to predict the diaphragm position throughout the imaging segment and correct the slice position in real time.
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    Critical analysis of techniques for normalising electromyographic data : from laboratory to clinical research
    (2008) Albertus, Yumna; Lambert, Mike; Derman, Wayne; Tucker, Ross; Noakes, Tim
    Measurements of muscle activity derived from surface EMG electrodes are variable due to both intrinsic and extrinsic factors. The intrinsic factors are endogenous in nature (features within the body) and include muscle fiber type, muscle fiber diameter and length, the amount of tissue between muscle and electrode, and depth and location of muscle with respect to the placement of electrodes (24). These biological factors vary between subjects and cannot be controlled. The extrinsic factors are experimental variables which are influenced by the researcher and can be controlled to some extent. Examples of extrinsic factors include the location, area, orientation, shape of electrodes and the distance between electrodes (interelectrode distance). In order to measure biological variation in the EMG signal, which is important in studies where surface EMG is used to gain understanding of physiological regulation, it is important to minimise the variation caused by these factors. This is in part achieved through the appropriate method of normalisation. The isometric maximal voluntary contraction (MVC) has been used as a standardmethod of normalisation for both static and dynamic exercises. However, researchers have recently improved the methods of normalisation by developing alternative techniques for the measurement of EMG during dynamic activities. By using the same type of movement for normalisation as during the trial, experimental errors can be reduced. The appropriate method of normalisation is defined as a method that is capable of showing repeatability, reliability (low intra-subject variation) and sensitivity to changes in EMG amplitude that is due to biological change and not the contribution of experimental factors. The aim of this thesis was to critically analyse alternative methods of EMG normalisation during dynamic exercise. The data should provide possible guidelines to researchers who are planning studies involving measurement of EMG activity during cycling, running and in clinical populations. Furthermore, the thesis aimed to illustrate that decisions regarding the most appropriate method of normalisation should be based on the study design, research question (absolute muscle activity or changes in muscle pattern) and the muscles being investigated.
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    Design and Development Towards a Novel Prosthesis for Total Shoulder Arthroplasty to Reduce Aseptic Glenoid Loosening
    (2018) Dey, Roopam; Sivarasu, Sudesh; Roche, Stephen
    Total shoulder arthroplasty (TSA) is the most common surgical solution, that helps in restoring the structural and functional integrity of a diseased glenohumeral (GH) joint with intact rotator-cuff. A 300% increase in the usage of TSA has been observed since 2007, along with 2.5% increase in revision rate. Aseptic glenoid loosening accounts for 37% of postsurgical failures in TSA. Eccentric loading of the prosthetic glenoid cup, leading to the “rocking horse” effect, is one of the prevalent causes of aseptic glenoid loosening. Current anatomical total shoulder prosthesis (ATSP) geometry does not consider all the GH morphometric features, for example the elliptical shape of the humeral head. Moreover, the morphometric studies leading to the initial ATSP design did not consider the GH morphology of any sub-Saharan population. Hence, there exists a gap in understanding of the implications of certain morphometric features on the functionality of a post-TSA GH joint. This thesis had two primary aims to address this gap in knowledge. Firstly, to study the GH morphometric variations between cohorts representing native European (Swiss) and native sub-Saharan (South African) populations. Secondly, to develop anatomically inspired ATSP design concepts and test them using biomechanical and finite element (FE) models, insilico, under standardised testing protocols. The morphometric analysis suggested that an average Swiss humeral head radius of curvature was larger (P<0.05) than the average South African humeral head. By comparing the biological head sizes, across both the populations, with the dimensions of the commercially available humeral heads, it can be inferred that suitable humeral prostheses are currently not available for individuals with head sizes >28mm or <19mm. Considering both the populations, the inherent shape of an average humeral head was found to be elliptical. The thickest region of the head was found to lie in the posterior region and not at the geometric center. Hertzian contact theory was applied to calculate the GH stresses produced by symmetric and asymmetric elliptical heads. Higher concentric stresses (P<0.001), within the acceptable limit for polyethylene, were observed to be imparted by the asymmetric heads. Population-specific musculoskeletal models were developed to study the post-TSA kinematic variation. When an identical range of motion (RoM) was performed by these models, population-specific variation in muscle moment arms was observed. The novel glenoid designs were not found to alter the post-surgical kinematics. FE models of the biradial, compartmental and pear-shaped glenoid implant designs were subjected to compressive and shear loading according to the American Society for Testing and Materials (ASTM). Using the bi-radial the glenoid cup, with thickened posterior-superior surface, anatomically relevant force distribution patterns could be replicated. Compartmentalising the glenoid prosthesis into concentric and eccentric regions with the gaps, proved to be highly beneficial. When compared to a commercially available glenoid prosthesis, the compartmental prosthesis was able to contain the GH forces to the concentric region for longer, delaying the eccentric loading and therefore potentially reducing the “rocking horse” effect. In the light of the above observations, two conclusions can be drawn from this thesis. Firstly, it would be beneficial if population-specific ATSP were made available for natives of certain geographic locations. Secondly, glenoid prosthesis designs could be compartmentalised to contain the GH joint forces within the concentric regions of the cup which might aid in the reduction of post-TSA complications.
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    Development of a 3D radial MR Imaging sequence to be used for (self) navigation during the scanning of the fetal brain in utero
    (2016) Morgan, Leah; Meintjes, Ernesta M; Van der Kouwe, Andre
    Imaging the fetal brain in utero is challenging due to the unpredictable motion of the fetus. Although ultra-fast MRI sequences are able to image a 2D slice in under a second, thus limiting the time in which fetal motion can corrupt images, Cartesian sampling makes these sequences sensitive to signal misregistration and motion-corruption. Corruption of a single 2D slice renders it impossible to reconstruct 3D volumes from these slices without complex slice-to-volume registration. There is a need for motion-robust sequences that can produce high-resolution 3D volumes of the fetal brain. The Siemens Cardiovascular sequence was edited to produce a new radial readout that sampled a 3D spherical volume of k-space with successive diametric spokes. The diameter end points map a spiral trajectory on the surface of a sphere. The trajectory was modified so that multiple sub-volumes of data are sampled during a single acquisition where M is the number of sub-spirals and N is the number of diametric spokes per sub-spiral. This allows reconstruction of individual sub-volumes of data to produce a series of low-resolution navigator images that can be co-registered to provide information on motion during the acquisition. In this way, a segmented sequence suited to self-navigation was developed. Imaging parameters for the 3D radial sequence were optimised based on theoretical calculations and scans performed in adult brains and abdomens. Optimum values for M and N needed to be determined. Increasing M for a constant total number of projections improves the temporal accuracy of motion tracking at the expense of decreased signal to noise ratio in the navigator images. The effects of breathing and rigid body motion on image quality were also compared between 3D radial and equivalent 3D Cartesian acquisitions. Custom reconstruction code was written to separate the incoming scan data according to the sub-spiral trajectories described within the sequence such that individual navigator images could be reconstructed. Successive sub-spiral images were co-registered to the first navigator image to quantify motion during the acquisition. The resulting transformation matrices were then applied to each sub-spiral image after reconstruction and co-registered sub-spiral images combined in image space to generate the final 3D volume. To improve the quality of navigator images, a method is presented to perform navigator image reconstruction at a lower base resolution, thus reducing streaking artifacts and improving the accuracy of image co-registrations. Finally, the methods developed were applied to two fetal scans. The radial sequence was shown to be more motion-robust than an equivalent Cartesian sequence. The minimum number of diametric spokes that provided navigator images that could be accurately co-registered when scanning an adult brain was N=256, which could be acquired in 1.25 s. For abdominal scans, the minimum number of spokes was N=1024, which could be acquired in about 6 s when water excitation is applied. However, the latter could potentially be reduced by reconstructing navigator images at a lower base resolution. Although fetal scans demonstrated poor image contrast, navigator images were able to track motion during the acquisition demonstrating the potential use of this method for self-navigation. In conclusion, a motion-robust radial sequence is presented with potential applications for prospective navigation during fetal MRI.
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    Dialogues with the dead : an osteological analysis of the palaeodemography and life history of the 18th and 19th century northern frontier in South Africa
    (2002) Peckmann, Tanya Rochelle; Morris, Alan
    Osteological, dental, and molecular analyses were conducted on remains from seven historical archaeological sites within South Africa. The emphasis was on the collection of lifestyle data for the purpose of adding to the unwritten history of indigenous South African peoples and to give voice to a once forgotten group of peoples. The demographic distribution reveals three different community dynamics: the Griqua sample are a pastoralist group incorporating some agricultural activities, the Colesberg individuals are an indigenous group resembling a migrant workers population living on the margins of society, and the Wolmaransstad demographics are suggestive of a Zabantu labouring community. All individuals are relatively healthy with low rates of dental disease and trauma and share similar growth patterns to living populations. However all of these individuals display high frequencies of porotic hyperostosis and cribra orbitalia, skeletal manifestations of iron deficiency anaemia. Many theories about the occurrence of anaemia are discussed and the hypothesis that, in these individuals, it is related to infection by the smallpox virus is investigated through the analysis of ancient DNA.
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    Dietary fat modulates the relationship between polymorphisms in the TNFA and IL-6 genes, and obesity and serum lipid concentrations in black and white South Afican women
    (2013) Joffe, Yael; Goedecke, Julia; Collins, Malcolm; Van der Merwe, Lize
    The primary aim of the thesis was to investigate associations between TNFA (TNFA-308 G>A and -238 G>A) and IL-6 (-174 G>C, IVS3+281 G>T, IVS4+869 A>G) sequence variants and obesity and serum lipid concentrations in black and white SA women. This included identifying sequence variants in the IL-6 gene with a reported high heterozygosity in both the white and black SA populations (rs1554606 and sr2069845). Dietary intake data of adequate reporters was then included in the analysis to investigate whether dietary fatty acid intake modulated the interactions between the TNFA and IL-6 SNPs (TNFA -308 G>A and -238 G>A & IL-6 -174 G>C, IVS3+281 G>T, IVS4+869 A>G) and obesity, measures of adiposity and serum lipid concentrations, and whether interactions identified differed between black and white women.