Showing items 1 - 20 of 8161

A model to facilitate nursing research supervisors in assisting postgraduate nursing students in Gauteng Province with timeous completion of studies

  • Authors: Mbombi, Masenyani Oupa
  • Date: 2024-12
  • Subjects: College dropouts -- Gauteng -- South Africa , Nursing -- Study and teaching -- Gauteng -- South Africa , Nursing -- Research
  • Language: English
  • Type: Doctoral theses , text
  • Identifier: http://hdl.handle.net/10948/69727 , vital:78014
  • Description: Many academically orientated persons aspire towards having postgraduate qualifications for various reasons. The reasons range from career development to expanding their knowledge in fields related to their current areas of professional specialisation. Some people however do not fulfil that personal need due to academic exclusion from their studies in the university related to taking too long to finish their studies while others just drop out. The current study aimed to develop a model that would assist in facilitating the supervision of postgraduate nursing students to complete their studies in the required and allocated time at nursing education institutions in Gauteng. The objectives of the study were to: explore and describe the perceptions of postgraduate research nursingstudents regarding their preparedness for a joint research journey; explore and describe the perceptions of research supervisors regarding theirpreparedness for a joint research journey; develop a conceptual framework that would underpin the development of amodel to facilitate the preparedness of postgraduate research nursing students(PGRNSs) and supervisors for the research journey at NEIs in Gauteng; and develop and describe a model to facilitate the preparedness of postgraduateresearch nursing students (PGRNSs) and inexperienced research supervisorsfor a joint research journey at NEIs at Gauteng. A theory-generative research design based on a qualitative, explorative, descriptive, and contextual research approach was adopted in this study. Purposive sampling was used to select 16 postgraduate nursing students (8 master’s and 8 doctoral) and 12 research supervisors from universities in Gauteng, South Africa. Data collection was conducted through voice-recorded unstructured interviews, which were transcribed verbatim and analysed using Tesch’s open coding method of data analysis. To ensure the trustworthiness of the study, the researcher used various strategies based on the criteria recommended in Guba’s model of trustworthiness. The criteria were credibility, transferability, confirmability and dependability. Ethical principles, such as respect for a person’s beneficence, non-maleficence, and justice were ensured during the data collection stage. Four broad themes (see Chapter 3) emerged from the data analysis. The themes were: Theme: perceptions regarding postgraduate supervision provided or received Theme: perceptions regarding preparedness for the research journey Theme: support systems influencing preparedness for the research journey Theme: Hope for change in the research progress and concerns to be considered Concept identification and analysis assisted the researcher in putting concepts in a relationship for the development of the model as guided by the six survey elements of Dickoff and James. Although the model was not tested, the researcher and the selected nursing experts were confident that the model is significant to nursing and other disciplines. The model was described and successfully evaluated by a panel of six nursing experts who acknowledged the clarity, generality, accessibility, simplicity, and significant contribution to the nursing environment. The guidelines and recommendations to implement the model in the nursing environment were developed to enhance the application of the model. The model aims to provide a theoretical and structural frame of reference to the head of the department and research supervisors in nursing for the facilitation of the preparedness of the postgraduate students and inexperienced supervisors for a joint research journey to ensure the timeous completion of postgraduate studies. The outcomes of the model include easing the struggle of students during their research studies for acceptable progress within the nursing environment of nursing education institutions. inexperienced research supervisors who experienced challenges to achieving optimum supervision in the nursing environment will also benefit if they apply the developed model. To enhance the applicability of the model, the researcher recommends that the model be tested in postgraduate studies for future benefits before implementation. , Thesis (PhD) -- Faculty of Health Sciences, School of Clinical Care & Medicinal Sciences, 2024
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  • Date Issued: 2024-12

A multistep synthesis of zidovudine in continuous flow systems

  • Authors: Kwakhanya, Mkwakwi
  • Date: 2024-12
  • Subjects: HIV -- South Africa , HIV infections -- Diagnosis , Antiretroviral agents -- South Africa
  • Language: English
  • Type: Doctoral theses , text
  • Identifier: http://hdl.handle.net/10948/69393 , vital:77251
  • Description: Universal access to antiretroviral drugs is still a challenge in developing nations. This promoted an investigation into an efficient process towards the synthesis of zidovudine (AZT), a nucleoside reverse transcriptase inhibitor (NRTI) that is used to treat HIV/AIDS. It was the first antiretroviral drug approved by the FDA and it is still widely used today. AZT works by blocking the enzyme reverse transcriptase, which is used by HIV to copy its genetic material. This prevents HIV from replicating and spreading throughout the body. AZT is usually taken in combination with other antiretroviral drugs. AZT was originally used as a single-drug therapy, but it is no longer recommended for this purpose as HIV can become resistant to AZT if it is used alone. Consequently, AZT is most commonly used as part of a combination therapy; this means that it is taken with other antiretroviral drugs. This helps to prevent HIV from becoming resistant to AZT. AZT can be used to prevent mother-to-child transmission of HIV; it is usually given to HIV-positive women during pregnancy and childbirth. AZT can also be used to treat post-exposure prophylaxis (PEP); this is a course of antiretroviral drugs that is taken after a possible exposure to HIV. The application of continuous flow microreactors to reaction chemistries, such as this, could provide a potentially practical solution that could be used to meet the rising needs for antiretroviral drugs in Africa and to give new opportunities for efficient local drug manufacture. Consequently, the focus of this research was to develop safe and efficient processes towards AZT by taking advantage of micro reactor technology. Furthermore, since there is no literature on continuous flow synthesis of this drug, this research extensively unearthed interesting continuous flow processes towards zidovudine. , Thesis (PhD) -- Faculty of Science, School of Biomolecular & Chemical Sciences, 2024
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  • Date Issued: 2024-12

A relevant intervention on nutrition transition among Isixhosa speaking people in Nelson Mandela Bay

  • Authors: Fordjour Afriyie, Vera
  • Date: 2024-12
  • Subjects: Nutrition -- South Africa -- Port Elizabeth , Nutrition -- Social aspects , Xhosa (African people) -- Nutrition
  • Language: English
  • Type: Doctoral theses , text
  • Identifier: http://hdl.handle.net/10948/69760 , vital:78026
  • Description: The nutrition transition, characterised by a shift from traditional, nutrient-dense diets to Westernised, energy-dense, and nutrient-poor diets, has significant health implications globally. In South Africa (SA), particularly among the isiXhosa-speaking population in Nelson Mandela Bay (NMB), this transition has led to the dual burden of undernutrition and overnutrition, increasing the prevalence of non-communicable diseases (NCDs) such as obesity and diabetes. Despite the prevalence of this nutrition phenomenon, limited research has explored the perceptions of nutrition transition among South African communities, although there is literature about the transition itself. Most studies on the research subject were undertaken in Asian and European countries and America. Generally, studies regarding the nutrition transition emphasise the importance of early public health interventions to prevent the transition from reaching critical levels. This research study aimed to answer the question: How do isiXhosa-speaking people in NMB perceive nutritional transition, and what are their knowledge and practices concerning traditional foods? This study’s primary aim was to identify and evaluate the NMB isiXhosa-speaking population’s perceptions regarding nutrition transition and their knowledge and practices concerning traditional foods. Subsequently, the study aimed to develop and test an educational intervention to promote traditional African diets and mitigate the adverse effects of nutrition transition. The researcher employed a multi-method approach, encompassing quantitative and qualitative methods and an exploratory, descriptive, and contextual approach to enhance the research design. Ethical principles guided the study, including autonomy, non-maleficence, beneficence, and justice. The study comprised two phases. Participants were selected through a stratified, clustered sampling technique. In the first phase, data were collected through in-depth interviews, focus group discussions (FGDs), a 24-hour dietary recall questionnaire, and a knowledge and practices The participants were isiXhosa-speaking NMB residents older than 18 years of age. The second phase utilised the first-phase findings to develop an intervention programme. The intervention was implemented, and its efficacy was evaluated through post-intervention surveys, sensory evaluation, and a three-month telephonic follow-up. The findings indicated a significant decline in traditional food knowledge (TFK) and practices among the participants, with a marked shift towards Westernised diets. The primary factors driving this transition were urbanisation, economic constraints, and a lack of awareness about the nutritional benefits of traditional foods. The intervention programme, which included educational workshops and a sensory evaluation using indigenous crops, resulted in improved knowledge and practices regarding indigenous crops among the participants. Post-intervention data showed increased dietary diversity and a greater inclusion of traditional foods in daily diets. The study concluded that nutrition transition poses a significant challenge to the health and well-being of isiXhosa-speaking individuals in NMB. However, targeted interventions that promote traditional African diets can effectively address this issue. The study recommends that policymakers and public health practitioners incorporate culturally relevant and community-driven strategies to promote traditional food consumption. Future research should focus on the long-term impacts of such interventions and explore scalable models for broader implementation. , Thesis (PhD) -- Faculty of Health Sciences, School of Behavioural & Lifestyle Sciences, 2024
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  • Date Issued: 2024-12

Assessing perceptions regarding sustainable growth of taverns in the Gqeberha liquor industry

  • Authors: Coutsourides, Peter Dimitri
  • Date: 2024-12
  • Subjects: Taverns (Inns) -- Port Elizabeth- Eastern Cape -- South Africa , Liquor industry -- Port Elizabeth -- Eastern Cape , Economic development -- Port Elizabeth -- Eastern Cape -- South Africa
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/69542 , vital:77710
  • Description: This study investigates the sustainable growth of taverns within the informal liquor industry in Gqeberha, South Africa. The informal sector is critical for economic development, employing 60% of the world's population and nearly 30% of South Africa's workforce. This study focuses on taverns, a prevalent form of small, medium, and micro-enterprises in South African townships. Despite their economic significance, these taverns face numerous challenges, including limited access to finance, inadequate infrastructure, regulatory hurdles, and competition from larger formal enterprises. The research explores the historical context of the liquor industry in South Africa, highlighting the legacy of racial inequality and the evolution of regulatory frameworks aimed at balancing industry growth and social equity. In addition, the literature covered topics relating to SMMEs and sustainable growth. The study employs a case study strategy and a qualitative methodology where 12 tavern owners in Gqeberha were interviewed using an interview schedule. The thematic data analysis revealed five main challenges that hinder taverns' sustainable growth, namely finance, government interventions and facilities, competition, the COVID-19 Pandemic and crime. In addition, three measures or themes of sustainable growth were identified for these enterprises, such as economic, social and environmental measures for sustainable growth. Finally, based on the findings, a major contribution of this study is the framework of sustainable growth enablers that were presented to SMMEs, including taverns. This study contributes to the understanding of SMMEs in the informal sector and offers practical recommendations for enhancing the sustainable growth of taverns. By addressing the identified challenges and leveraging the proposed enablers, policymakers and stakeholders can create a more supportive environment for these enterprises, ultimately contributing to broader economic development and poverty reduction in South Africa. The insights gained from this study are intended to inform future policies and support mechanisms that can help these enterprises thrive despite their myriad challenges. , Thesis (MCom) -- Faculty of Business and Economic Sciences, School of Management Sciences, 2024
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  • Date Issued: 2024-12

Associations between patterns of wild ungulate patch use, soil carbon and albedo in montane grasslands

  • Authors: Mc Gregor, Steven
  • Date: 2024-12
  • Subjects: Grassland ecology , Global environmental change , Climatic changes
  • Language: English
  • Type: Doctoral theses , text
  • Identifier: http://hdl.handle.net/10948/69382 , vital:77250
  • Description: Grassy ecosystems are essential for human survival, providing key services including food production, water provisioning and moderating climate. Yet, grassy ecosystems remain undervalued due to misconceptions that they are remnants of degraded states of forest – a view that continues to influence climate change policies. This thesis explores the links between wild, free-roaming ungulate grazers and climate drivers, including carbon storage and surface albedo (i.e., reflectance of solar radiation), through their impacts on vegetation and soils. Using black wildebeest (Connochaetes gnou) as a model wild species, I compared their grazing patterns in an Afromontane grassland in the eastern Karoo, South Africa, to those of short-duration cattle grazing systems in similar nearby grasslands (Chapter 2). While short-duration grazing aims to mimic spatiotemporal wild ungulate grazing patterns to supposedly enhance ecosystem functioning and soil carbon stocks, I found that wildebeest had ~50% shorter grazing durations and much shorter rest intervals (1-5 days versus 60-365 days), revealing key differences in grazing patterns that may affect vegetation and climate feedbacks. Next, I examined spatial variations in soil organic carbon (SOC) stocks between grass growth forms that differ in grazing tolerance (Chapter 3). Red grass (Themeda triandra) tussock patches, sensitive to frequent grazing, had higher SOC to a soil depth of 20 cm (61.45 ± 1.59 Mg C·ha-1)than intensively grazed, prostrate-growing Cynodon dactylon grazing lawns (55.43 ± 3.40Mg C·ha-1), likely due to greater shading and soil moisture beneath tussocks which drives microbial decomposition. Seasonal albedo variations were then assessed across distinct grassland patch types among seasons to determine whether albedo varies seasonally at fine patch-scales between grass patches, between shrub and grass patches, and with grazing (Chapter 4). Albedo was lower during the growing season compared to dormancy, and was consistently lower in dwarf shrub (Pentzia incana) encroached patches compared to grass patches. No albedo differences between grazed and less-grazed tussock grass patches of the same species were found, although intensively grazed grazing lawns had consistently higher albedo than most patch types. Finally, I evaluated trade-offs between plant carbon, albedo, and their impacts on radiative forcing (i.e., atmospheric warming/cooling) resulting from patch type changes commonly found in grassy ecosystems (Chapter 5). The loss of perennial grass cover resulted in the highest net positive (warming) effect, mostly due to reduced root biomass. Additionally, shrub encroachment into all patches lowered albedo, but led to negative (cooling) effects from shrub encroachment into bare ground patches due to biomass gains. This thesis challenges current views of grassy landscapes and short-duration grazing systems, emphasizing the need to rethink climate change mitigation strategies to prioritize maintaining heterogeneity, while enhancing carbon sequestration and albedo in grassy ecosystems. , Thesis (PhD) -- Faculty of Science, School of Environmental Sciences, 2024
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  • Date Issued: 2024-12

Characterization of the molecular mechanism(s) of cannabinoid-induced paraptosis in breast cancer cells

  • Authors: de la Harpe, Amy
  • Date: 2024-12
  • Subjects: Cannabinoids , Cannabinoids -- Therapeutic use , Cancer cells
  • Language: English
  • Type: Doctoral theses , text
  • Identifier: http://hdl.handle.net/10948/68818 , vital:77120
  • Description: Natural products have been extensively studied for their anticancer potential, and several widely used anticancer drugs have natural origins. Many studies have demonstrated that natural compounds can induce paraptosis in various tumour cell lines. Paraptosis is a caspase-independent cell death mechanism characterised by cytoplasmic vacuolation arising from the endoplasmic reticulum (ER) and the mitochondria. The molecular mechanism of paraptosis is unclear; however, the literature indicates that dysregulation of calcium signalling plays an important role in paraptosis induction, particularly calcium-mediated signalling between the ER and mitochondria. This study aimed to identify and characterise the mechanism of cell death induced by a phytocannabinoid ratio which induced significant cytoplasmic vacuolation in the MCF7 breast cancer cell line. Several techniques were employed to address the aim of the study. The crystal violet assay was used to detect changes in viability. Several pathway inhibitors, as well as fluorescent staining and analysis using high-content screening (HCS), were used to measure the induction of various cell death mechanisms. Morphological changes were investigated using light and transmission electron microscopy. The phytocannabinoid ratio induced significant cell death and cytoplasmic vacuolation in MCF7 cells; however, the same trend was not observed in the MCF10A non-tumourigenic breast cell line. No cell cycle arrest, apoptosis, necrosis, autophagy, or ferroptosis induction was detected in MCF7 cells, suggesting that an alternative mechanism of cell death was induced. Vacuolation and cell death induced by the phytocannabinoid ratio were inhibited by cycloheximide, suggesting a dependence on protein synthesis, which is characteristic of paraptosis induction. The mechanism of paraptosis induction by the phytocannabinoid ratio was investigated, and it was found that treatment 1) induced ER dilation and mitochondrial swelling; 2) induced significant ER stress, mitochondrial calcium overload, and mitochondrial dysfunction which appeared to be mediated by the voltage-dependent anion channel (VDAC); and 3) significantly impaired all mitochondrial metabolic pathways. Overall, the data demonstrated that paraptosis induced by the cannabinoid ratio is mediated by calcium flux from the ER to the mitochondria. This highlighted a novel mechanism of phytocannabinoid-induced cell death and emphasised the anti-cancer potential of the use of phytocannabinoid ratios as opposed to individual phytocannabinoids, expanding their potential for use as anticancer agents. , Thesis (PhD) -- Faculty of Science, School of Biomolecular & Chemical Sciences, 2024
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  • Date Issued: 2024-12

Co-generated learnings from hopes-an NRF grant funded university engagement project

  • Authors: Quvile, Xola Bulumko
  • Date: 2024-12
  • Subjects: National Research Foundation (South Africa) , Research grants -- South Africa , Education, Higher -- South Africa
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/68366 , vital:76990
  • Description: The study had sought to understand the systemic and individual factors that facilitated or inhibited the NRF grant-funded HOPES Project. HOPES collaborated with the Centre for the Community School in the Faculty of Education, and various communities of practice (COPs) in existing school communities in the Eastern Cape Province of South Africa. The project applied a critical participatory action research work to develop a framework for school improvement and in the process contribute to making schools beacons of hope. This research provides insights into how an NRF community engagement grant project team (HOPES) navigated external and internal factors such as COVID-19, rules regulating the grant, and multiple realities of the stakeholders at play. The study was qualitative and used the critical participatory action research design. The study purposively and conveniently sampled seven HOPES Project team members to collect data via focus groups and individual interviews and collected secondary data from NRF HOPES annual project reports. The study findings improved the participants' understanding of their journey, and the co-generated knowledge shed light on how NFR and community engagement grant funders could promote enabling conditions towards achieving individual scholars and collective project outcomes. The study findings provide learnings for the Faculty of Education and the Nelson Mandela University on how extrinsic and intrinsic enablers and barriers can be addressed to optimise a project of this nature. , Thesis (MEd) -- Faculty of Education, School of Postgraduate Education, 2024
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  • Date Issued: 2024-12

Collaborative conservation governance in multifunctional landscapes: a contextual analysis of two South African biosphere reserves in the Boland

  • Authors: Klaver, Michael
  • Date: 2024-12
  • Subjects: Unesco -- Programme on Man and the Biosphere , Nature conservation -- South Africa , Biosphere
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/68924 , vital:77164
  • Description: The Man and the Biosphere Programme (MAB) has been earmarked as one of the most promising ways of tackling the grand challenges of our time and achieving the Sustainable Development Goals. Furthermore, it may have the potential to make positive contributions to one of the most troubling conservation challenges of our time – winning spaces for large carnivores in human-dominated landscapes. This study aims to assess the interpretation and implementation of MAB in two South African Biosphere Reserves (BRs) and explore how BRs as landscape level collaborative initiatives can support Cape leopard conservation in the Boland region of the Western Cape, South Africa. This study is informed by two objectives. First, to understand how the chosen governance strategy and structure of two South African BRs have helped to achieve a context appropriate interpretation and actioning of MAB in the landscape. Second, to understand how landscape-level collaborative conservation initiatives support leopard conservation across a multifunctional landscape. This study takes on a mixed methods approach in which qualitative data takes priority and quantitative data is used for support in an embedded multiple-case study design. The sampling techniques used include purposive sampling of strategically targeted participants, i.e. those governing BRs and those leading the collaborative initiative and snowballing thereon. Data collection included a combination of semi-structure interviews (n=20) (the principal collection method), a review of archival, policy and other documents (n=15), and supported by a mixed methods survey questionnaire (n=5). Data were analysed through thematic and content analysis. Findings suggest that organisations working at a landscape-level utilise forms of adaptive co-management and/or governance as a means to being both adaptive and collaborative. Important themes which emerge include cross-sectoral approaches, networks, leadership and trust for building partnerships, shared visions and ‘filling gaps’ left by, or collaborating with the state to fulfil mutually beneficial objectives. This research provides empirical studies on MAB, important for sharing knowledge across the World Network of BRs, meeting the need for further research on collaborative initiatives in social-ecological systems and conservation programmes for large free-roaming carnivores in multifunctional landscapes. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Science & Management, 2024
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  • Date Issued: 2024-12

Collaborative conservation governance in multifunctional landscapes: a contextual analysis of two South African Biosphere Reserves in the Boland

  • Authors: Klaver, Michael
  • Date: 2024-12
  • Subjects: Unesco. -- Programme on Man and the Biosphere , Nature conservation -- South Africa , Social ecology
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/68918 , vital:77165
  • Description: The Man and the Biosphere Programme (MAB) has been earmarked as one of the most promising ways of tackling the grand challenges of our time and achieving the Sustainable Development Goals. Furthermore, it may have the potential to make positive contributions to one of the most troubling conservation challenges of our time – winning spaces for large carnivores in human-dominated landscapes. This study aims to assess the interpretation and implementation of MAB in two South African Biosphere Reserves (BRs) and explore how BRs as landscape level collaborative initiatives can support Cape leopard conservation in the Boland region of the Western Cape, South Africa. This study is informed by two objectives. First, to understand how the chosen governance strategy and structure of two South African BRs have helped to achieve a context appropriate interpretation and actioning of MAB in the landscape. Second, to understand how landscape-level collaborative conservation initiatives support leopard conservation across a multifunctional landscape. This study takes on a mixed methods approach in which qualitative data takes priority and quantitative data is used for support in an embedded multiple-case study design. The sampling techniques used include purposive sampling of strategically targeted participants, i.e. those governing BRs and those leading the collaborative initiative and snowballing thereon. Data collection included a combination of semi-structure interviews (n=20) (the principal collection method), a review of archival, policy and other documents (n=15), and supported by a mixed methods survey questionnaire (n=5). Data were analysed through thematic and content analysis. Findings suggest that organisations working at a landscape-level utilise forms of adaptive co-management and/or governance as a means to being both adaptive and collaborative. Important themes which emerge include cross-sectoral approaches, networks, leadership and trust for building partnerships, shared visions and ‘filling gaps’ left by, or collaborating with the state to fulfil mutually beneficial objectives. This research provides empirical studies on MAB, important for sharing knowledge across the World Network of BRs, meeting the need for further research on collaborative initiatives in social-ecological systems and conservation programmes for large free-roaming carnivores in multifunctional landscapes. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2024
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  • Date Issued: 2024-12

Comparative study of the effect of iloprost on neuroinflammatory changes in c8-b4 microglial cells and murine model of trypanosomiasis

  • Authors: Jacobs, Ashleigh
  • Date: 2024-12
  • Subjects: Neuroimmunology , DNA -- Methylation , Nervous system -- Degeneration
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/68895 , vital:77160
  • Description: Neurodegenerative conditions significantly impact well-being and quality of life in individuals with major symptoms including mood disorders, cognitive decline, and psychiatric disturbances, often resulting from neuroinflammation triggered by immune responses to bacterial or parasitic infections such as gram-negative bacteria or Human African Trypanosomiasis. Microglia play a crucial role in both neurotoxicity and cellular processes involved in restoring the neural health. Exploring the therapeutic potential of prostacyclin and its analogues in regulating microglia responses to inflammatory insult and treating Trypanosoma brucei (T.b) infection remains an unexplored area. The aim of this study was to assess the potential neuroprotective effects of Iloprost through comparative analysis of neuroinflammatory responses in both microglial cells exposed to lipopolysaccharide (LPS) and mouse brains infected with T.b brucei. In phase I of this study both resting and LPS treated C8-B4 microglial cells were exposed to varying concentrations of Iloprost. The effects of Iloprost on LPS-induced inflammation were analysed using immunofluorescence to detect microglial activation and differentiate between pro and anti-inflammatory phenotypes. Furthermore, pro and anti-inflammatory cytokine secretion was determined using an ELISA, in addition gene expression analysis was carried out using quantitative polymerase chain reaction (qPCR). Also, DNA methylation status of C8-B4 cells exposed to LPS challenge alone or in combination with various concentrations of Iloprost were determined using bisulfite sequencing technique followed by qPCR. In phase II of the study, a total of twenty-four Albino Swiss male mice (8-10 weeks old) were divided into four treatment groups with 6 mice in each group. All treatment groups except the non-infected control were inoculated with the T.b brucei parasite. One group received a single intraperitoneal injection of Diminazene aceturate (4 mg kg-1)while the remaining group received repeated intraperitoneal injections of Iloprost (200 μg kg-1). On day ten of the study, mouse brains were removed on ice using forceps. The hippocampal tissues were dissected out and processed for quantification of gene expression changes in pro and anti-inflammatory cytokines. Overall, the findings of this study indicate that LPS-induced pro-inflammatory cytokine, TNF-α and IL-1β, secretion and gene expression is down-regulated in C8-B4 microglial cells treated with Iloprost. Furthermore, there was a significant up-regulation in the expression of anti-inflammatory genes, particularly ARG-1, CD206, BDNF and CREB in response to Iloprost treatment following LPS-induced inflammation. This study is also the first to confirm M2 microglial polarization with Iloprost treatment in both resting and LPS treated cells. However, hypermethylation at CREB and BDNF promoter regions was observed 24 hours after Iloprost treatment. Additionally, Iloprost reversed hypomethylation at the BDNF promoter region that had been induced by LPS treatment. The rodent model also indicated a downregulation in the pro-inflammatory cytokine, IL-1β, expression and upregulation of BDNF transcription in T.b brucei infected mice treated with repeated doses of Iloprost. In conclusion, determining the immunomodulatory roles of Iloprost in both in vitro and in vivo models of neuroinflammation could assist in the development of alternative therapy for neurodegenerative disease. , Thesis (MSc) -- Faculty of Science, School of Biomolecular & Chemical Sciences, 2024
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  • Date Issued: 2024-12

Development of density-dependent and density-independent competition models to understand single tree growth responses in eucalyptus stands

  • Authors: Kepe, Lulama Patrick
  • Date: 2024-12
  • Subjects: Forests and forestry -- Mathematical models , Trees -- Growth -- Mathematical models , Eucalyptus grandis
  • Language: English
  • Type: Doctoral theses , text
  • Identifier: http://hdl.handle.net/10948/68906 , vital:77161
  • Description: In commercial forest production, predicted yields based on mensuration recommendations are seldom realized, and minimal silvicultural standards based on results from trial blocks do not account for the relationship between initial planting density and final stocking. Growth models designed to investigate management options must employ competition indices to provide reliable predictions under extreme silviculture. The competition a tree experiences until the day of harvest is a strong driver for quality and volume of timber. Hence, this turns the regulation of competition into an integral part of silviculture. According to Little et al. (2003), it is known that, at some stage after canopy closure, individual trees in a stand will begin to compete for resources. To investigate competition amongst individual trees, a re-purposed Bayesian mixed effects model, similar in characteristics to a Sire model used for estimating breeding values, is proposed. In animal breeding models, the Sire Model allows for the inclusion of a numerator relationship matrix containing inbreeding coefficients. In a similar way, documented competition indices are included in the model in an attempt to estimate posterior probabilities of specifically selected individual trees being the strongest growers during different stages in the tree growth cycle. Estimated tree growth indices were determined and used to make probability statements in order to rank the individually selected trees based on the amount of growth observed. A tree growth index is a measurement of a tree’s average growth performance in relation to the average growth performance of all trees on the same plot. As different competition indices are introduced into the model, changes in the probabilities are observed and compared to what is visually observed on the plot, i.e. if the tree with the highest probability of being the strongest grower, is actually not necessarily the largest tree of the group of selected trees, but rather the tree that presented the largest amount of growth of the selected group of trees during that specific growth season. From a randomly selected plot, a group of neighboring trees were randomly selected. Four specifically selected target trees were then identified from this group of 25 selected trees, and analyzed. For this discussion, for example, from our randomly selected group of 25 neighboring trees, tree 54, tree 56, tree 86, and tree 88 were specifically selected for further analysis. For these specifically selected trees, marginal posterior densities for the variance components and random effects were then estimated using the Gibbs Sampler, where competition between the trees was assumed present, as well as for the case where it was assumed that no competition takes place between the individually selected trees. In the latter case, an identity matrix was utilized in the Gibbs sampling algorithm where it was assumed that there is no competition between the trees. Both a distance independent competition index (Lorimer,1983), and a distance dependent index (Hegyi, 1974), were used to generate the numerator relationship matrix A that was used by the Gibbs sampling algorithm in the case where competition was assumed between individual trees. Also a new distance dependent index was proposed and tested in this study as well. Results from the selected plot, with a 1500 stems per hectare (sph) density, indicated that there were no significant differences in the average growth between these selected trees. However, the marginal posterior densities of the fixed effects indicated that there was a significant difference in the average growth rates between the base level conditions and other levels determined for each of these fixed effect factors for the selected trees, since their 95% equal tails credibility intervals, did not contain zero. This therefore indicated that the specific treatment applied on the plot, had a significant effect on the individual tree growth. Results when competition was assumed present, revealed that the estimated marginal posterior densities for the error variance as well as tree variance, were severely positively skewed. , Thesis (PhD) -- Faculty of Science, School of Natural Resource Science & Management, 2024
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  • Date Issued: 2024-12

Experiences of accoucheurs caring for women during confinement in public maternity units in the O.R. Tambo District Municipality

  • Authors: Wabane, Malibongwe
  • Date: 2024-12
  • Subjects: Midwifery -- South Africa -- Eastern Cape , Labor (Obstetrics) -- South Africa -- Eastern Cape , Hospital care -- South Africa -- Eastern Cape
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/69782 , vital:78034
  • Description: Midwifery is a health science profession that deals with women in their confinement period, including the caring of new-borns. Historically, the midwifery profession has evolved from being a female-dominated profession to an occupation followed by both males and females. However, accoucheurs working in public maternity units face various challenges, such as a lack of support and discrimination from their female counterparts and women during confinement. These challenges are based mainly on tradition, religion, and the history of midwifery, a female-dominant profession. The potential effects of these challenges can be seen when women during confinement refuse maternal care from accoucheurs. As a result of this prejudice, accoucheurs may be unable to practice their midwifery skills and may choose other disciplines involving less intimate care. Such acts of refusal of care by women during confinement and these various challenges faced by accoucheurs in public maternity units are common in rural areas. The O.R. Tambo District Municipality (ORTDM) comprises predominantly of rural areas where culture and tradition play an essential role in the community’s life. This study employed a qualitative research design with an explorative, descriptive, and contextual approach to gain a deeper understanding of the experiences of accoucheurs caring for women during confinement in public maternity units in the ORTDM. The purpose of this study was to explore and describe the experiences of accoucheurs caring for women during confinement in public maternity units in the ORTDM to make recommendations to nursing managers regarding the provision of optimal support to accoucheurs working in the rural Eastern Cape. The target population of the study was all accoucheurs working in public maternity units in the ORTDM. Snowball sampling, a non-probability sampling method, was used to select participants who met the inclusion criteria and were voluntarily willing to participate in the study. The data collection method used was one-on-one semistructured interviews, which were also captured using a digital voice recorder. Field notes were used during data collection to enhance the researcher’s understanding of accoucheurs’ nonverbal experiences. The sample size, which was 12 accoucheurs, was determined by data saturation. Data was transcribed verbatim, and Braun and Clark’s (2006) steps of reflexive thematic analysis (RTA) were used as a framework for data analysis. Lincoln and Guba’s model of trustworthiness was used to maintain the quality of the study by employing credibility, transferability, confirmability, and dependability (Lincoln and Guba, 1985). The ethical principles that guided this study with human participants were the principles of respect for persons, beneficence, non-maleficence, and justice as outlined in the Belmont Report and its application (2015:14) Three main themes emerged from the data analysis, namely: • Theme 1: Accoucheurs experienced specific factors that enabled them to care for women during confinement in public maternity units. • Theme 2: Accoucheurs identified barriers that disabled them in caring for women during confinement in public maternity units. • Theme 3: Recommendations for nurse managers by accoucheurs to optimize their ability to care for women during confinement in public maternity units. Direct quotations from the raw data and relevant literature supported the research study results and were discussed in-depth in Chapter Four. Various recommendations were discussed in Chapter Five of this study that present options for nurse managers to optimize the support for accoucheurs who were caring for women during confinement in public maternity units.Midwifery is a health science profession that deals with women in their confinement period, including the caring of new-borns. Historically, the midwifery profession has evolved from being a female-dominated profession to an occupation followed by both males and females. However, accoucheurs working in public maternity units face various challenges, such as a lack of support and discrimination from their female counterparts and women during confinement. These challenges are based mainly on tradition, religion, and the history of midwifery, a female-dominant profession. The potential effects of these challenges can be seen when women during confinement refuse maternal care from accoucheurs. As a result of this prejudice, accoucheurs may be unable to practice their midwifery skills and may choose other disciplines involving less intimate care. Such acts of refusal of care by women during confinement and these various challenges faced by accoucheurs in public maternity units are common in rural areas. The O.R. Tambo District Municipality (ORTDM) comprises predominantly of rural areas where culture and tradition play an essential role in the community’s life. This study employed a qualitative research design with an explorative, descriptive, and contextual approach to gain a deeper understanding of the experiences of accoucheurs caring for women during confinement in public maternity units in the ORTDM. The purpose of this study was to explore and describe the experiences of accoucheurs caring for women during confinement in public maternity units in the ORTDM to make recommendations to nursing managers regarding the provision of optimal support to accoucheurs working in the rural Eastern Cape. The target population of the study was all accoucheurs working in public maternity units in the ORTDM. Snowball sampling, a non-probability sampling method, was used to select participants who met the inclusion criteria and were voluntarily willing to participate in the study. The data collection method used was one-on-one semistructured interviews, which were also captured using a digital voice recorder. Field notes were used during data collection to enhance the researcher’s understanding of accoucheurs’ nonverbal experiences. The sample size, which was 12 accoucheurs, was determined by data saturation. Data was transcribed verbatim, and Braun and Clark’s (2006) steps of reflexive thematic analysis (RTA) were used as a framework for data analysis. Lincoln and Guba’s model of trustworthiness was used to maintain the quality of the study by employing credibility, transferability, confirmability, and dependability (Lincoln and Guba, 1985). The ethical principles that guided this study with human participants were the principles of respect for persons, beneficence, non-maleficence, and justice as outlined in the Belmont Report and its application (2015:14) Three main themes emerged from the data analysis, namely: • Theme 1: Accoucheurs experienced specific factors that enabled them to care for women during confinement in public maternity units. • Theme 2: Accoucheurs identified barriers that disabled them in caring for women during confinement in public maternity units. • Theme 3: Recommendations for nurse managers by accoucheurs to optimize their ability to care for women during confinement in public maternity units. Direct quotations from the raw data and relevant literature supported the research study results and were discussed in-depth in Chapter Four. Various recommendations were discussed in Chapter Five of this study that present options for nurse managers to optimize the support for accoucheurs who were caring for women during confinement in public maternity units. , Thesis (MCur) -- Faculty of Health Sciences, School of Clinical Care & Medicinal Sciences, 2024
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  • Date Issued: 2024-12

Exploiting continuous flow technology to develop synthetic processes for active pharmaceutical ingredients: prilocaine and betrixaban

  • Authors: Sagandira, Mellisa Brenda
  • Date: 2024-12
  • Subjects: Pharmaceutical technology , Drug development , Pharmaceutical biotechnology
  • Language: English
  • Type: Doctoral theses , text
  • Identifier: http://hdl.handle.net/10948/69464 , vital:77259
  • Description: The dilemma of providing affordable health care has long haunted African countries due to the continuously growing disease burden as the population increases. Africa accounts for only 3 % of global drug production and imports over 90 % of its life saving medicines at a yearly cost of US$14 billion according to the African Development Bank (AfDB). Attaining Africa’s Agenda 2063, Universal Health Coverage (UHC) and Sustainable development Goal 3 (SDG3) aspirations of ensuring healthy and well-nourished citizens remain difficult given this situation. This over-dependence on imports has led to drug shortages, high pricing, poor quality medicines and unguaranteed supply chains, thus there still remains an unmet need. The advent of the COVID-19 pandemic worsened this situation as many countries curbed exports resulting in a crisis across the continent. Africa experienced high demand of medicines compared to prepandemic level, which threatened the health care of the continent. This situation can be addressed by establishment of local pharmaceutical manufacturing capability through adoption of advanced manufacturing technologies such as continuous flow chemistry. In this research, we therefore seek to exploit continuous flow chemistry, an enabling technology to develop safe and efficient synthetic processes for active pharmaceutical ingredients: prilocaine and betrixaban as case studies. To the best of our knowledge there is no reported work on synthetic processes towards prilocaine and betrixaban under continuous flow conditions, thus this research extensively unearthed interesting continuous flow processes towards these APIs. In a broader view, establishment of local APIs production will ease Africa’s over-dependence on imports, which will in turn address issues such as drug shortages, poor quality and high pricing. This work aims to demonstrate how continuous flow technology can be useful for the establishment of local APIs manufacturing, which will inherently revolutionize medicines availability, affordability and accessibility to the greater population. Chapter one begins with a brief overview on Africa’s disease burden and pharmaceutical supply chain. Continuous flow chemistry is introduced with its benefits and limitations discussed. Lastly a mini review of examples of APIs synthesised in continuous flow is presented. In chapter two, we demonstrate how continuous flow technology can be exploited to develop synthetic processes towards prilocaine as our first case study. This chapter clearly demonstrates how highly exothermic nitration reactions can be safely handled by using continuous flow systems. Additionally, the use of a micro structured mixer facilitated biphasic nitration of toluene to be carried out with enhanced mass transfer, which inherently led to improved selectivity of ortho-nitrotoluene (preferred isomer) to 79 % compared to 59 % achieved in batch mode. A two-step synthesis of ortho-toluidine via biphasic nitration of toluene and nitroreduction was demonstrated with the incorporation of a Zaiput liquid/liquid separator to facilitate in-line separation. Comprehensive optimisation studies were carried out in flow. Prilocaine was synthesised in 74 % overall yield in a 13.6 min residence time for all processes. In chapter three, we demonstrate how continuous flow technology can be exploited to develop synthetic processes towards betrixaban. Synthetic routes towards betrixaban feature two amide bond formation transformations. Pleasingly, we explored multistep chemistry to develop amide synthesis protocols in flow without interruption for work up and isolation. An overall yield of 92 % was achieved to get to key intermediate to betrixaban in 8 min total residence time. Chapter four demonstrates the robustness of developed amide synthesis protocols, a key transformation in synthetic routes towards prilocaine and betrixaban in continuous flow systems. A total of 22 amides were synthesised via flow multistep processes with isolated yields greater than 82 %. All the compounds were characterized using infrared spectroscopy (IR), and nuclear magnetic resonance (NMR). Quantification of the reaction mixtures were carried out using highperformance liquid chromatography (HPLC) and gas chromatography (GC). , Thesis (PhD) -- Faculty of Science, School of Biomolecular & Chemical Sciences, 2024
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  • Date Issued: 2024-12

Exploring children’s understandings of gender using critical literacy in a reading club

  • Authors: Jansen, Lincoln Lee , Surname, name
  • Date: 2024-12
  • Subjects: Book clubs (Discussion groups) -- South Africa , Literacy -- Study and teaching (Elementary) , Literacy -- Study and teaching (Middle school)
  • Language: English
  • Type: Doctoral theses , text
  • Identifier: http://hdl.handle.net/10948/68333 , vital:76976
  • Description: School literacy practices have always favoured traditional, gender stereotypical portrayals of characters in books. These portrayals are not troublesome as it helps children build a sense of identity. However, these portrayals often fail to represent people in more diverse ways and thus does not reflect how societies have progressed. These narrow portrayals are also often limiting and do not take into consideration people’s personal interests which can lead to them being ostracised and marginalised. The People’s Republic of China is the context for this study where traditional, conservative views are upheld about ways of being and doing for males and females. This is a qualitative study within the interpretivist paradigm which recognised the individual perceptions of participants within their specific sociocultural context. By establishing a reading club as a Third Space for literacy engagement, this study sought to explore how grade 2 learners at a school in Beijing, China responded to traditional and diverse portrayals of characters in books. This study regarded the establishment of a reading club as an empowering practice as it allowed a safe space for the participants to freely share their deliberations about ways of being in the world. Coupled with critical literacy as a practice, participants took a critical stance in instances of gender bias and injustices and in doing so, allowed them to accentuate their morality. Findings of this study suggest that the Chinese participants had very flexible ideas about ways of being and doing in the world as long as these did not conflict with their understandings of the law. Participants also upheld that gender performances and gendered behaviour are open to all with impunity. The findings of this study also highlight the importance of providing diverse literature to children as this helps them to deal with, and examine, issues they might not ordinarily encounter in a safe way and in doing so, expand their worldviews and cultivate empathy. , Thesis (PhD) -- Faculty of Education, School of Primary Schooling, 2024
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  • Date Issued: 2024-12

Exploring resilience in undergraduate nursing students at a nursing education institution in the Eastern Cape, South Africa

  • Authors: Blatti, Jenny
  • Date: 2024-12
  • Subjects: Nursing students -- South Africa -- Eastern Cape -- Psychology , Nursing -- Study and teaching -- South Africa , Nursing schools -- Faculty -- South Africa -- Eastern Cape
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/69805 , vital:78036
  • Description: Undergraduate nursing students worldwide experience stress and anxiety due to the demands of nursing education, which include challenges related to academic workloads and the clinical environment. This, in turn, may impede programme completion and continuation in nursing careers. Resilience is recognised as an effective attribute for nursing students in adapting to stressors and has been found to have a beneficial impact on learning experiences, academic performance, and professional practice. Despite numerous research studies conducted on resilience in the health professions, there remains little empirical work that has explored undergraduate nursing students' understanding and experience of their resilience. The purpose of this study was thus to explore undergraduate nursing students’ perceptions of their resilience at a nursing education institution in the Eastern Cape, South Africa, and to compile recommendations for a resilience training programme in undergraduate nursing education. A qualitative, explorative, descriptive, and contextual research design was implemented, with the study underpinned by the Resilience Ecological Stress Model. Third and fourth-year nursing students were recruited by purposive sampling, following which data was collected online by means of eleven individual semi-structured interviews conducted and recorded on the Microsoft (MS) Teams platform. Data was analysed using Braun and Clarke’s six steps of reflexive thematic analysis, generating codes and themes. The following themes were identified: participants’ perceptions of their challenges while studying nursing, participants’ understanding and experience of resilience, and participants’ views on the unique requirements of the degree in nursing. Findings indicated that nursing students perceive resilience as a beneficial attribute in mitigating the stress and anxiety evoked by their diverse challenges. Recommendations for nursing education were formulated based on the theoretical framework constructs and the findings of the study. , Thesis (MCur) -- Faculty of Health Sciences, School of Clinical Care & Medicinal Sciences, 2024
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  • Date Issued: 2024-12

Extending psychological praxis within South Africa: exploring healers’ perceptions of treatment plurality

  • Authors: Yew-Siong, Lauren
  • Date: 2024-12
  • Subjects: Traditional medicine -- South Africa , Psychology -- Africa , Clinical health psychology
  • Language: English
  • Type: Doctoral theses , text
  • Identifier: http://hdl.handle.net/10948/69771 , vital:78032
  • Description: The prevailing psychological praxis in South Africa predominantly follows western paradigms for defining, classifying, and diagnosing health and illness; falling short in encompassing the diverse mental healthcare reality. Scarce resources, inadequate infrastructure, and the interplay of religio-cultural beliefs intersect, shaping how psychological disturbances are perceived and how treatment is sought- especially for patients who do not ascribe to one treatment modality, or one paradigm. Therefore, this study explored ideas and notions surrounding treatment plurality held by healers (that being psychologists, psychiatrists, and traditional healers), within the South African context. The research utilised a qualitative exploratory-descriptive research methodology with a phenomenological research design. The researcher then employed purposive and snowball sampling to recruit participants. Thereafter, the researcher conducted online semi-structured interviews, and applied Braun and Clarke's (2006) thematic analysis to analyse the data. The following themes were then unpacked: 1) Healers’ perceptions of treatment plurality; 2) The need for collaboration between various disciplines; 3) Education as a key factor in pluralism; 4) Healer ethics and malpractice; 5) The lack of governmental funding and resources. The results suggest the need for a pluralistic mental healthcare approach in South Africa, bridging western and traditional practices. Yet, challenges stemming from inadequate governmental funding, resources, policies, and ethical guidelines hinder its development and implementation. Therefore, it would take more than one set of guidelines to implement pluralistic treatment within South African mental healthcare. For this purpose, the researcher decided to create a blueprint for various developments that is needed to make a pluralistic approach a reality in South Africa. These findings encouraged the researcher to develop: 1) Guidelines for the Provision of Collaborative Care in Mental Healthcare Services; 2) Guidelines for South African governmental policy that foster pluralism and collaborative care in the mental healthcare system; 3) A pluralistic medical aid scheme; 4) A module blueprint that could potentially be included in a professional master’s programme, as well as the inclusion of a theory the researcher has developed, named the Pluralism-oriented Mental Healthcare Theory. , Thesis (PhD) -- Faculty of Health Sciences, School of Behavioural & Lifestyle Sciences, 2023
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  • Date Issued: 2024-12

Ground- and marine water inputs into supratidal microbialite systems along the Nelson Mandela Bay coastline

  • Authors: O’Connell, Tristin Wade
  • Date: 2024-12
  • Subjects: Groundwater -- South Africa -- Nelson Mandela Bay , Earth sciences , Geology
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/69415 , vital:77253
  • Description: Extant supratidal microbialite systems are especially numerous and well-developed along the rocky coastline of Nelson Mandela Bay (NMB), South Africa. Precipitating in a hydrological environment formed by the input of constant, fresh groundwater discharge and periodic marine water intrusion these systems form part of the longest uninterrupted geological record of life on Earth (~3.4 billion years ago). Microbialites are layered organosedimentary deposits which potentially provide a window into historical environmental conditions. This study focusses on the fresh groundwater and saline marine water inputs of these microbialite pools, and the corresponding microbialite accretion rates. Severe regional drought in the NMB area resulted in rapid anthropogenic groundwater abstraction of the coastal aquifers on which the microbialite systems rely for groundwater inflow. This study provides insight into the current state of the coastal aquifers of NMB through the quantification of groundwater discharge via microbialite systems in terms of volume and flow rate. This is paired with in situ hourly microbialite pool water temperature and conductivity data to determine the effect of marine intrusion and the role of tidal flushing in these pools. A spatial assessment of groundwater discharge conducted using quantitative and semi-quantitative measurement techniques indicated that the total discharge of the study area is ~45.8 L/s or 3.8 ML/d. Over 1,500 freshwater seeps were identified, of which 78% showed microbialite deposits. Topography of the coast indicated that this might influence the flowrate. Calcareous sediment of sandy beaches within the study area supported lower discharge, while rocky shores with lithified rock had higher discharge. Seasonal differences in the volume discharged were evident, with winter having higher flowrates. Flow paths and discharge rates are affected by inland lithological differences and indicate variability linked to rainfall events that show lag effects depending on aquifer origins. This study is the first spatial analysis of the volume of groundwater discharging through microbialite-fed seeps. Marine intrusion and the corresponding pool flushing dynamics identified three types of microbailite systems: groundwater-dominant, dynamic input, and fast-reacting sites. A novel measurement technique for microbialite accretion determined accretion rates for systems under varying pool conditions. Although the average accretion rates of the Nelson Mandela Bay microbialites were in the order of erosion of 0.35 mm per year, there was significant variability in these measurements likely linked to differential localised vulnerability to storm events or responses to groundwater ix flow variability. It remains to be determined whether these factors are definitive risks to the sensitive supratidal microbialite systems. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2024
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  • Date Issued: 2024-12

Gymnopilus junonius and Rhodofomitopsis lilacinogilva: In vitro evaluation of antimycobacterial activity, safety assessment and isolation of active compounds

  • Authors: Didloff, Jenske
  • Date: 2024-12
  • Subjects: Antibacterial agents , Plants, Useful -- South Africa , Medicinal plants -- South Africa
  • Language: English
  • Type: Doctoral theses , text
  • Identifier: http://hdl.handle.net/10948/68840 , vital:77122
  • Description: Tuberculosis remains a significant public health challenge due to the complexity and compliance issues of its treatment, the prevalence of latent infections, the high rate of HIV co-infection, and the spread of drug-resistant strains. This highlights the need to search for new antimycobacterial drugs. Natural products have historically been used as sources for the discovery of pharmaceuticals. Although medicinal macrofungi have been exploited in traditional folk medicines for the treatment of various diseases, research into their antimycobacterial activity remains limited.The aim of this study was to isolate, identify, and characterise the antimycobacterial compound(s) present in ethanol fruiting body extracts of Gymnopilus junonius (Fr.) P.D. Orton (Hymenogastraceae) and Rhodofomitopsis lilacinogilva (Berk.) B.K. Cui, M.L. Han, & Y.C. Dai (Fomitopsidaceae), as well as to investigate their mechanism of action and potential toxicity using in vitro and in vivo screening methods.Bioassay-guided fractionation was conducted using column chromatography and preparative thin-layer chromatography to isolate the active antimycobacterial fraction/compound from ethanol extracts of G. junonius and R. lilacinogilva. Antimycobacterial activity against M. tuberculosis H37Rv was screened using a resazurin microplate assay (REMA). The chemical structure was elucidated employing 1D-(1H NMR) and 2D NMR spectroscopy (HSQC, HMBC) techniques, along with High- Performance Liquid Chromatography High-Resolution Electron Spray Ionisation Mass Spectrometry (HPLC-HRESI-MS). Transmission electron microscopy (TEM) was utilised to observe the ultrastructural changes in M. tuberculosis induced by the active fraction/compound. Toxicity assessment was performed on African green monkeykidney (Vero) and human hepatoma (C3A) cell lines using various staining techniques to observe the potential risk for hepatotoxicity (CellRox orange, TMRE, and MTG staining) and genotoxicity (NucRed staining). In vivo toxicity of extracts was evaluated using a zebrafish embryo/larvae model to observe developmental and teratogenic effects.The bioassay-guided fractionation of G. junonius and R. lilacinogilva extracts yielded an active compound and a fraction displaying inhibitory activity against M. tuberculosis, with MIC values of 31.25 μg/mL and 250 μg/mL, respectively. Gymnopilene was identified as the main active compound isolated from G. junonius, while fraction 8 from R. lilacinogilva contained a predominant constituent resembling a pachymic acid derivative. Transmission electron microscopy revealed ultrastructural damage to M. tuberculosis cells upon treatment with gymnopilene and fraction 8, which was observed as the disruption and disintegration of the cell wall. In vitro toxicity assessment indicated a reduction in the cell density in both Vero and C3A cell lines following exposure to the fractions/gymnopilene. Although there were no significant alterations in the production of reactive oxygen species, changes in mitochondrial dynamics were observed. Genotoxic assessment showed no significant changes. In vivo toxicity assessment showed no significant effects for G. junonius against the zebrafish embryos/larvae, whereas R. lilacinogilva remained toxic and induced developmental abnormalities over a 72-hour time period.The findings of this study highlight the potential of macrofungi as a valuable source of bioactive compounds, confirming the significance of natural products in drug discovery. Notably, this research represents the first to demonstrate that the predominant compound, gymnopilene, isolated from G. junonius exhibits inhibitory activity against M. tuberculosis, contributing to the novelty of the study. Furthermore, the study expands our understanding of the antimycobacterial properties of the selected macrofungal species, G. junonius and R. lilacinogilva, by demonstrating the ultrastructural damage to M. tuberculosis cell wall induced by treatment. However, it is important to recognise the potential toxicity identified through in vitro and/or in vivo screening assays. The observed toxicity may hamper their suitability formdrug development. Future investigations could explore the inclusion of additional in vitro based models, perhaps more complex and physiologically relevant models alongside the in vivo screening model to assess the therapeutic potential of isolated fractions/compounds. , Thesis (PhD) -- Faculty of Science, School of Biomolecular & Chemical Sciences, 2024
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  • Date Issued: 2024-12

Investigating the purported medicinal properties of cannabinoid containing products available for human consumption in South Africa

  • Authors: Stark, Nicole Jade
  • Date: 2024-12
  • Subjects: Thin layer chromatography , Tetrahydrocannabinol , Cannabinoids
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/69716 , vital:78013
  • Description: Cannabis has until recently, in some countries, been classified as an illicit, illegal drug. In South Africa, the sale of marijuana (Cannabis sativa) is still illegal, but there has been an amendment of legislation in the governing of the use of marijuana in that the private use of marijuana was decriminalised in September 2018. This has led to questions about whether the recreational use of Cannabis should be legalised and what is the potential social implications of this legislation moving forward (Mokwena, 2019). This study aimed to assess whether the indications and consequently the concentrations associated with the declared purported use of cannabinoid containing products correspond with the information declared on the label and conform to the regulatory limits set out for these products. The objectives of this study were to explore: the range of products available in South Africa, the prescribed use and dosage of the product and to test the accuracy of the reported information on the product labelling regarding the cannabinoid content. This investigation pursued a quantitative approach that is empirical and comprised of laboratory-based experiments. A minimum of seven samples of different liquid preparations of products, reported to contain cannabinoids and being sold without the need for a prescription or licence were tested with the aid of Thin Layer Chromatography (TLC), to separate individual compounds from the many that could be found in these Cannabis products. The results of this testing of cannabidiol (CBD) and tetrahydrocannabinol (THC) and, where applicable, their concentrations were determined. Using the data collected and review of available literature, assessments were made as to whether the products tested conform to the regulatory standards and contained the cannabinoids as stated on the labelling. From the data obtained findings were that not all products currently available on the South African market correspond to the information reported on the label or conform to the regulatory standards. , Thesis (MPharm) -- Faculty of Health Sciences, School of Clinical Care & Medicinal Sciences, 2024
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  • Date Issued: 2024-12

Portfolio effect and bet-hedging adaptations in sea turtles

  • Authors: Hoekstra, Shaun
  • Date: 2024-12
  • Subjects: Wildlife conservation , Sea turtles -- South Africa , Animal behavior
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/68873 , vital:77153
  • Description: A great proportion of marine species are at risk of going extinct as a result of profound changes in the world’s oceans, primarily driven by human activities. Sea turtles are not exempt from this fate. Despite sea turtles being exposed to a range of environmental conditions and threats that vary in frequency and intensity, these ancient marine reptiles have persisted for millennia. In the past, sea turtles have been able to adapt to natural perturbations while other animal groups have not. The ability of sea turtles to adapt to contemporary changes in conditions, produced by human activities, has become limited. The persistence of sea turtles may be explained by the application of a concept termed “portfolio effect”. An aggregate system is more stable and less prone to fluctuations over time (i.e. portfolio effect) if a diversity of finer components comprises the entire system and displays asynchronous fluctuations over time. Biological entities (e.g. species measured by the abundance trend) may achieve long-term stability even though the individual components (e.g. populations measured in abundance trend) display weak or negative correlations with each other in space and time. Different sea turtle populations may display independent trends in abundances over time, resulting in a portfolio effect at species levels. Trends in sea turtle abundances may be affected by individual behaviour. The adoption of bet-hedging adaptations may enable populations to thrive despite environmental changes or stochasticity, by lowering short-term fitness in exchange for maximising long-term fitness. Individual sea turtles may exhibit bet-hedging adaptations through changes in their temporal nesting behaviour, including the remigration interval. Since remigration interval length regulates the number of nesting females per nesting season, changes in remigration interval will affect abundance trends. The ability of individuals to change their remigration interval allows them to “skip” the breeding migration when environmental conditions seem unfavourable. The overall aim of this thesis was to investigate potential reasons for observed sea turtle abundance trends at species, population, and rookery levels. I tested whether the portfolio effect applies to sea turtles by analysing and interpreting spatiotemporal trends in loggerhead (Caretta caretta) and leatherback (Dermochelys coriacea) abundances at the population and species levels using global datasets. The application of bet-hedging strategies was tested at a local level using data from the long-term monitoring program for South African nesting sea turtles. The majority of loggerhead rookeries displayed an increase in abundance over time, while most leatherback rookeries declined (Chapter 2). Population growth rates also differed among rookeries within Regional Management Units (RMUs) (Chapter 2). This diversity in abundance trends among rookeries suggested spatiotemporal variation in environmental conditions, threats and/or level of protection accompanying sea turtles. The species-level growth rate for both species displayed an overall increase in abundance over time. However, larger (more turtles) leatherback rookeries/RMUs experienced more rapid declines in abundance compared to smaller rookeries/RMUs, resulting in a recent species-level decline. Uncorrelated trends in abundances at the RMU-level could have stabilised species-level trends. Differences in the remigration intervals as a possible bet-hedging adaptation could potentially explain differences in population recovery rates between South Africa’s loggerhead and leatherback sea turtles (Chapter 3), but found no evidence that individuals from either species exhibit bet-hedging adaptations. Loggerheads, however, have increased their remigration intervals over time, while leatherbacks have not. These increases were accompanied by declines in adult body size (previously established) which could be an effect of diminishing foraging area quality. The increased remigration interval shown by loggerheads may be a response rather than an adaptation to the prevailing environmental conditions that impact their food supply in their foraging areas. The population growth rate of leatherback sea turtles may surpass that of the loggerheads in the near future, although there is a global decline in abundance (Chapter 2). This dissertation provides information on possible reasons for observed trends in sea turtle abundances at various levels of biological organisation. While a variety of factors have the potential to influence trends in sea turtle abundance, the possible occurrence of portfolio effects and investigating nesting behaviour may resolve any uncertainties regarding the reasons for observed trends in abundance. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2024
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  • Date Issued: 2024-12
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