Electronic Theses and Dissertations (Masters)
Permanent URI for this collectionhttps://hdl.handle.net/10539/37931
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Item Micro-architecture of the human postnatal maxilla in relation to tooth development and eruption(University of the Witwatersrand, Johannesburg, 2024) Mhlathi, Xolisiwe; Hutchinson, Erin; Small, CandiceThe growth, modeling and remodeling of the maxilla are shaped by the biomechanical forces exerted on it. As functional demands of the masticatory system become more complex due to dental development and eruption, the intensity and complexity of the biomechanical forces increases and as such influences the associated bony micro-architecture. The knowledge gained from assessing the impact of these changes on the micro-architecture of the maxilla is important in the clinical and forensic contexts. Thus, this study aimed to assess changes in the micro- architecture of the alveolar region of postnatal and sub-adult human maxilla in relation to dental development and eruption. The study sample included seventy-nine individuals, subdivided into three groups according to dental development stages: deciduous dentition (n = 28; 0-5 years), mixed dentition (n = 9; 6-12 years), and permanent dentition (n = 42; 13-18 years). Maxillae were scanned using micro-computed tomography. Seven regions were selected along the buccal, lingual, and the apical surfaces of each dental crypt for evaluation of micro-architecture, which included bone volume fraction (BV/TV), trabecular thickness (TbTh), trabecular spacing (TbSp), material surface to material volume (BS/BV), and trabecular number (TbN). The micro-architecture of the maxilla changed from a more porous to a less porous nature, following patterns of bone remodeling during growth. These changes included an increase in BV/TV while BS/BV and TbN both significantly decreased. Thus, the trabeculae became more mineralized and decreased in number as they thickened. No significant differences were observed in TbTh and TbSp between the dentition groups. The observed micro-architecture reflects changes in the state of the dentition as well as adjustments to the complex functional environment of the oral cavity complexItem Is it fair to limit access to free human papillomavirus vaccinations to only girls in public schools in South Africa?(University of the Witwatersrand, Johannesburg, 2024) Scheepers, Vanessa ChristinaGender-neutral Human Papillomavirus (HPV) vaccination programs, covering girls and boys, are necessary to combat the global rise in HPV-related cancers and escalating treatment costs. HPV vaccination is the primary preventative intervention for both men and women. In South Africa, it is freely available to adolescent girls in public schools, excluding girls in private schools and boys. This exclusion deprives them of the benefits of free HPV vaccination, potentially exposing them to a greater risk of cancer, and incurring more costs to society in the end. I apply Kantian ethics and rule utilitarianism to evaluate and argue that the current South African school-based HPV program is unfair and morally unjustified in limiting free access to HPV vaccination to only girls in public schools. I specifically examine Kant’s Formula of Humanity and the Formula of Universal Law to evaluate the ethical dimensions of the policy and show that the policy has significant shortcomings in terms of equality, autonomy, and universality from a Kantian perspective. I further demonstrate that a policy excluding certain groups based on gender and socio-economic status is not aligned with the principles of rule utilitarianism because it fails to maximise overall well-being, perpetuates inequalities, hinders optimal vaccine coverage, and neglects the potential benefits of gender-neutral vaccination. I address potential counterarguments that proponents of the current policy might present from both a Kantian and a utilitarian viewpoint. I advocate for a more just and ethical approach and recommend a revision of the HPV vaccination policy to align with Kantian and utilitarian principles. I show that both Kantian ethics and rule utilitarianism support a gender-neutral HPV vaccination strategy in the South African context. Gender- neutral coverage of HPV vaccination ensures free and equitable access to all adolescents who can benefit from it, irrespective of sex, gender, school type, or socio-economic circumstances. A gender-neutral approach to HPV vaccination is more aligned with the South African ConstitutionItem Do governments have any prima facie duties to fund influenza vaccination (for the elderly in sa) and adults 65 years and above to vaccinate against influenza, respectively?(University of the Witwatersrand, Johannesburg, 2023) Sarangarajan, Ruach; Ewuoso, CorneliusIn this dissertation, I draw on the thinking about solidarity, reciprocity, distributive justice, incompleteness and conviviality grounded in African philosophy broadly, including African ethics, African epistemology, African aesthetics, African metaphysics and African logic, to name a few, to argue that institutions, particularly the South African (SA) government, have a prima facie responsibility to fund the influenza vaccination for adults 65 years and above. Equally, I draw on the moral norms arising from the same values grounded in African philosophy to argue that adults 65 years old have a prima facie duty to vaccinate against influenza. These claims address three core issues relevant to fostering influenza vaccine access: availability, affordability and acceptability. While the former claim ensures that influenza vaccinations are affordable and available to the target population group, the latter underscores the obligation of adults 65 years and above to vaccinate to address acceptability issues. Although the dissertation focuses specifically on the South African government to defend its core thesis, I believe the arguments can reasonably be adapted to address the responsibilities of other African governments and older persons in other regions. Notably, these responsibilities are that the SA government should make influenza vaccines freely available for adults 65 years and above in public and private health facilities, provided financial allocation and their extant relationships allow for this. Additionally, the SA government has a responsibility to improve influenza vaccine procurement and availability in the country, preferably through increasing manufacturing capabilities. Furthermore, the dissertation argues that adults 65 years and above have a prima facie responsibility to vaccinate against influenza. Notably, adults 65 years and above have a duty of conviviality to act in ways that limit harm to them and others. This project is intrinsically valuable to promote epistemic justice, thereby contributing towards the decolonization of the global healthcare system. Moreover, this project has social significance in contributing to mitigation efforts against future public health challenges associated with population ageing in resource-limited developing African nations, wherein the impact of population transition will be most feltItem Postmortem modifications of skeletal elements caused by common small southern African scavenging mammals found in a peri-urban environment(University of the Witwatersrand, Johannesburg, 2024) Da Costa, Roxanne Rebelo; Keyes, Craig AdamThe definition of taphonomy is everchanging and has been adapted from the original use to explain fossilization of animal remains to aiding in forensic investigations. Forensic taphonomy has helped estimate postmortem interval timelines and aid in understanding what happened to a body postmortem. A taphonomic variable of interest is animal scavenging. Animal scavenging can hinder forensic investigations through the alteration or deletion of evidence and the scattering of remains. The aim of the study was to describe the nature of postmortem modifications of skeletal elements caused by common small scavenging animals found in peri-urban environments in southern Africa. Understanding scavenging and scattering patterns of common animals found in a peri-urban environment in South Africa can aid in locating skeletal elements in forensic investigations. In this study, bovine skeletal elements were scattered at the National Zoological Gardens in Pretoria, in the enclosures of genets, servals, a warthog, and suricates. The elements remained in the enclosures for a week, after which they were collected, and the process was replicated three times. The samples were then macerated, analysed, and photographed at the Johannesburg Forensic Pathology Services. Scores were the most commonly observed postmortem modifications caused by all species studied and they were mainly superficial, indicating they were more likely caused by claws rather than the teeth of the animal. A chi-square test was conducted to test whether an association existed between the location on the skeletal element scavenged and the scavenging species. The statistic proved that there was an association and that each scavenging species studied have a preference for specific locations and skeletal elements that they scavenge on. A scoring system was developed to describe the intensity of modifications inflicted on the skeletal elements. The Cohen’s Kappa coefficient showed that the scoring method produced reliable scores. This is the first forensic taphonomic study to describe the modifications caused by genets, servals, and suricates. The results of the study can assist forensic anthropologists in the assessment of postmortem taphonomic alterations to skeletal elements in peri-urban environments in Southern Africa.Item Should commercial surrogacy be permissible in South Africa?(University of the Witwatersrand, Johannesburg, 2024) Jafta, Nonhlanhla Angel; Ewuoso, CorneliusThis dissertation is mostly a conceptual or normative project arguing that commercial surrogacy should be permissible in South Africa. I defend this claim using African-inspired principlism, emphasising principles of respect for persons and living in harmonious relationships. This is achieved through valuing relationships within communities and respecting people by respecting their autonomous decision-making capacities. It is also achieved by recognising the interconnectedness of people and that a person is a person through other people, which is called UbuntuItem Epistemic (in)justice, social identity and the Black Box problem in patient care(University of the Witwatersrand, Johannesburg, 2024) Khan, Muneerah; Ewuoso, CorneliusThis research report draws on (for the first time) the moral norms arising from the nuanced accounts of epistemic (in)justice in the work of decolonial scholars, and social identity in the work of relational autonomists to defend the thesis that using AI in patient care in light of the Black Box problem is deeply problematic and is ethically impermissible. This does not necessarily doom AI since it may be used for other purposes within the healthcare system. The report highlights what needs to happen to align AI with the moral norms it draws on. Deeper thinking – from backgrounds other than decolonial scholarship and relational autonomy – about the impact of AI on the human experience needs to be done to appreciate any other barriers that may exist. Future studies can take up this task.Item Design and synthesis of a nanocapsule system for transdermal delivery of lignocaine across the skin(University of the Witwatersrand, Johannesburg, 2024) Makha, Lerato Mathabelo; Choonara, Yahya E.; Ubanako, Philemon; Makhathini, SifisoPain is a major health problem that is caused by an emotional and sensory experience due to injury of tissues and can be differentiated as acute or chronic. Pain protects humans by assisting in making us aware that there is body injury or potentially damaging situations. If acute pain is not treated correctly, it can lead to chronic pain. Pain can be treated by several classes of medications including analgesics, Non-steroidal Anti-inflammatory drugs (NSAIDs), opioids, anti-depressants, and local anaesthetics. These medicines are administered orally. Although this is the preferred route of administration, it has many inherent limitations that can negatively impact the drug's desired pharmacological effects. Since the skin is the most convenient and accessible region for medication administration, innovative delivery techniques like Transdermal Drug Delivery Systems (TDDS) have been developed to circumvent the drawbacks of traditional drug delivery routes. This method has displayed fewer side effects experienced with conventional oral medications like gastric irritation and first-pass hepatic metabolism causing low blood concentration of the drug leading to low therapeutic effect. Nonetheless, the stratum corneum (SC), the skin's outermost layer, functions as a strong barrier to prevent most medications from penetrating the skin. Much attention has been paid to the use of nanocarriers as a transdermal delivery system of different accessible pharmaceuticals through the SC with the potential to have local or systemic effects to treat various disorders (Alexander et al., 2012). The purpose of this report was to synthesize Lignocaine (LIG)-loaded nanocapsules to evaluate their potential to transport LIG across the skin for increased effectiveness and fewer side effects. Lignocaine-loaded nanocapsules (LIG-PLGA-PC) were prepared by employing the solvent displacement technique. Aqueous phase consisted of 200 mg of Tween® 80 in 30 ml of purified water. The mixture was ultrasonicated for few minutes then put under electronic magnetic agitation. Organic phase was prepared by dissolving 125 mg of PLGA, 250 mg of PC and 30 mg of LIG in 5 ml of chloroform. Under probe sonication, organic phase was added drop wise to the aqueous phase and was allowed to stir overnight to remove the organic solvent. The formulated nanosystem was then frozen and lyophilized (FreeZone® 2,5, Labconco®, Kansas City, MS, USA) at -80 °C for 48 hours to yield a powder and analyzed using different analytical techniques. Four samples were prepared with three samples having a drug loaded in the organic phase. The fourth sample was blank, without the drug in the organic phase. The synthesised nanoparticles were characterized using Scanning Electron Microscopy (SEM), zetasizer, Ultraviolet (UV) spectroscopy, Fourier transform infrared (FTIR) spectroscopy and Thermogravimetric Analysis (TGA). SEM clarified the configuration of the surface and shape of the nanocapsules by beaming electrons that interacted with the sample's atoms to produce three-dimensional surface topography. Using the zeta-sizer, the size of nanoparticles was found to be around 139.8 nm and a polydispersity index (PDI) of 0.182 a while the zeta potential was -48,2 mV. A drug entrapment efficacy (DEE) percentage of 72 % was achieved. LIG release studies showed a sustained release over a 24-hour period. The FTIR spectral evaluation of drug loaded sample showed a vibration at 3000–2800 cm−1 indicating a N-H stretch, and 1750-1735 cm−1 presented with a C=O stretching group. At 1250–1020 cm−1 there is a C-N stretching confirming the presence of an amine group. Thermogravimetric Analysis (TGA) thermal studies indicated that the LIG nanoparticulate structure increased the thermal stability of LIG. To investigate the biocompatibility of the nanoformulation, immortalized human keratinocytes (HaCaT) were treated with LIG-PLGA-PC copolymeric nanocapsules and an MTT (3-(4,5- dimethylthiazole-2-yl)-2,5-diphenyltetrazolium bromide) assay was conducted to evaluate the cytotoxicity of the treatments. Absorbance values were measured at 570 nm employing a Thermo Lab systems Multiskan MK3 microplate reader. From the cytotoxicity study conducted, at 48-hour, LIG-PLGA-PC nano formulation showed increased cell viability of 102, 103, and 110 % for 6,25 μg/ml, 3,125 μg/ml, 1,5625 μg/ml concentrations respectively. The blank nanocapsule showed a cell viability of 99, 98 and 100 % at concentrations of 6,25 μg/ml, 3,125 μg/ml, and 1,5625 μg/ml. The HaCaT cell micrographs showed cell proliferation on the drug loaded as well as plain drug figures. This can be confirmed by the MTT assay that the nanoformulation was non-cytotoxic with predicted biocompatibility. The combined experiments and findings of the LIG-PLGA-PC nanocapsule synthesis demonstrated that further studies and investigations are required to show that these nanoparticles can be used as a possible formulation for TDDS medication delivery of LIG for pain treatment.Item The moral obligation to include pregnant women in clinical trials(University of the Witwatersrand, Johannesburg, 2024) Ramtahal, Kieara-Lee; Behrens, KevinMany pregnancies are complicated by serious medical conditions that require treatment, and despite the need to use medication during pregnancy, the majority of clinical trials do not include the pregnant population, which leaves pregnant women with limited “robust” data regarding the safety and effectiveness of medications that they may require during pregnancy (Little & Wickremsinhe, 2017, p.1). In this report, I examine the reasons provided for the exclusion of pregnant women from clinical trials and the ethical reasons for their inclusion. I argue that, 1. the exclusion of pregnant women as participants in clinical trials could potentially expose future pregnant women to significant harms, 2. the benefits arising out of the inclusion of pregnant women in clinical trials far exceeds the possible harms to the pregnant women trial participants and their fetuses and 3. pregnant women deserve fair access to research trials where their participation will involve access to potential benefits. I also discuss objections to my arguments and provide a response. In conclusion, I contend that pregnant women should be included in clinical trials unless there are compelling reasons for exclusion.Item Mechanisms of cell death induced by betulinic acid and dihydroartemisinin polymer-drug conjugates on pancreatic cancer cells(University of the Witwatersrand, Johannesburg, 2023) Moisane, Karabo SekopiIntroduction: Pancreatic cancer (PC) is a lethal malignancy characterised by a poor response to standard chemotherapy. Like other cancers, PC employs apoptosis evasion mechanisms to ensure tumour survival. This makes apoptosis evasion an important cancer hallmark that can be targeted for effective treatment. Betulinic acid (BA) and Dihydroartemisinin (DHA) have shown promising anticancer properties via induction of apoptosis; however, limitations such as poor aqueous solubility and high molecular weights limit their overall therapeutic effect. Polymer drug conjugation is a promising solution. This project aimed to confirm the cytotoxic potential and determine the mechanism of cell death induced by BA and DHA polymer-drug conjugates on pancreatic cancer cells. Methodology: The cytotoxic effect of the free drugs, BA and DHA, and the complimentary conjugates on Vero (non-cancerous cells) and MIA PaCa-2 pancreatic cancer cells was confirmed using tetrazolium salt assays. The antioxidant potential and effect of reactive oxygen species (ROS) activity were conducted using the 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and N, N-Dimethyl-p-phenylenediamine (DEPPD) assays. The mode of cell death and the effect of the drugs on the cycling characteristics of the cells were determined using flow cytometric assays. Their effect on the expression of proapoptotic genes was assessed using real-time polymerase chain reaction (PCR). The apoptosis evasion mechanism of the pancreatic cancer cells was determined using the human nuclear factor kappa-B p65 subunit (NF-κB/p65) enzyme-linked immunosorbent assay (ELISA) kit. Results: The conjugates PEG-BA and PEG-DHA demonstrated lower IC50 values compared to the free compounds BA and DHA with a selectivity index of 3.00 and 1.61 for the conjugates, and 1.12 and 1.71 for BA and DHA, respectively. Antioxidant analysis showed that the free drugs, BA and DHA, had a weak antioxidant potential with IC50 values of more than 100 μM while the conjugates resulted in lower IC50. PEG-BA (4 μM) induced higher apoptosis than free BA (53.07% vs 7.68%) on the MIA PaCa-2 cells. Furthermore, PEG- DHA resulted in 50.99% of the MIA PaCa-2 cells undergoing apoptosis compared to free DHA (12.90%). Both conjugates induced low levels of necrosis (< 1%). After treatment with PEG-BA, the MIA PaCa-2 cells underwent a dose-dependent Sub-G1 arrest, which further indicated apoptosis. Similarly, PEG-DHA also induced a Sub-G1 arrest in addition to G2/M arrest on the MIA PaCa-2 cells. Compared to the free BA, PEG-BA treatment resulted in the highest overexpression of the following proapoptotic genes: TNF, BAX, CASPASE 3, CASPASE 2 and CASPASE 8. Both BA and PEG-BA induced a moderate increase in the concentration of NF-κB compared to the untreated MIA PaCa-2 cells. Conclusion: This study confirmed that conjugation of the polymer PEG to natural compounds with anticancer properties, such as BA, further improves the apoptosis-inducing ability against pancreatic cancer cells with the overexpression of proapoptotic genes, necessitating further explorationItem A retrospective study of the epidemiology, management and outcomes of patients with dialysis-requiring acute kidney injury, over a 24-month period, at Helen Joseph Hospital, Johannesburg, South Africa(University of the Witwatersrand, Johannesburg, 2024) Naidu, YashikaBackground Dialysis-requiring acute kidney injury (AKI) carries significant morbidity and mortality. A cohort of patients was reviewed at Helen Joseph Hospital (HJH) to contribute to local knowledge on the epidemiology, referral patterns, and outcome of dialysis-requiring AKI. Methods A retrospective review was conducted of patients receiving dialysis for AKI at HJH between 1 January 2019 and 31 December 2020. Patient demographics and aetiologies of AKI were described. Effects of baseline characteristics and aetiology of AKI on patient survival, duration of hospitalisation, and renal function recovery were analysed using Cox proportional hazards modelling and binomial regression analyses. Results Dialysis-requiring AKI occurred in younger median age. Human immunodeficiency virus (HIV) infection (38.7%), hypertension (27.4%) and diabetes mellitus (12.3%) were common comorbidities. Community-acquired AKI predominated with significant renal dysfunction at presentation. Leading causes of AKI were sepsis (51.9%) and hypovolaemia (26.4%). Mortality was high (56.6%). Age and diabetes increased mortality and reduced renal recovery. Sepsis (HR 1.48, 95% CI 1.37–1.60, P < 0.001) and cardiorenal syndrome (CRS) type 1 (HR 1.78, 95% CI (1.57–2.01, P < 0.001) increased mortality. HIV infection did not increase the risk of mortality and showed an increased likelihood of renal recovery (OR 1.71, 95% CI 1.51–1.95, P < 0.001). Chronic kidney disease was prevalent in survivors. Conclusion Results resemble that of other low- and middle-income countries. People living with HIV may be at increased risk of dialysis-requiring AKI. AKI carries a high mortality rate. Sepsis and CRS carry an increased risk of death; sepsis-associated AKI and comorbid diabetes are associated with reduced odds of renal recovery to dialysis-free levels.