Masters Degrees (Clinical Pharmacology)

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Browsing Masters Degrees (Clinical Pharmacology) by browse.metadata.advisor "Ollewagen, Tracey"

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    The effect of Dolutegravir on redox and vascular integrity
    (Stellenbosch : Stellenbosch University, 2022-10) Conradie, Janica; Smith, Carine; Ollewagen, Tracey; Faculty of Medicine and Health Sciences. Dept. of Medicine. Division of Clinical Pharmacology.
    ENGLISH ABSTRACT: Background: Of the estimated 7.2 million people living with HIV (PLWH) in South Africa, more than 50% are on antiretroviral (ARV) medication. Dolutegravir (DTG), an integrase strand transfer inhibitor (INSTI), is increasingly used in South Africa (and Africa) as one of the first line treatments for HIV. Both in vitro and clinical studies indicate that DTG-based therapies have been associated with adverse effects (such as abnormal weight gain, hyperglycemia, and neurological dysfunction) alongside increased oxidative stress. Another disease state common in the South African context is obesity. DTG is administered to an individual regardless of their weight. As obesity is also associated with oxidative stress and inflammation, this might be a potential confounding factor in the efficacy and safety of DTG treatment. Endothelial dysfunction is one of the most common risk factors associated with non-communicable disease (such as obesity and CVD) and would therefore be an important phenomenon to investigate in the context of ARVs and obesity. Aim: This study aimed to elucidate potential effects of chronic DTG on redox profile and endothelial integrity in the presence or absence of overfeeding as a confounder. Methods: Adult zebrafish were subjected to chronic administration of DTG in the absence and presence of obesity (overfeeding model) over a period of 2 weeks. The lean zebrafish received Hikari dry pellets twice per day, whereas the overfed fish received the same food, six times per day over 4 weeks. A parallel 12-week DTG administration study was also executed in lean male and female Wistar rats. Body mass, reactive oxygen species (ROS) levels (hydrogen peroxide (H2O2)) and vascular endothelial tight junctions (claudin-5 and ZO-1) and adherens junction (VE-Cadherin) protein profile were evaluated. Results: DTG did not have a significant effect on the body mass of adult zebrafish or rats. DTG administration showed no detrimental effect on ROS levels in either zebrafish or rats. When considering the effect of DTG on the expression of tight and adherens junction proteins, DTG showed no effect on the expression of ZO-1 and Claudin-5 in both zebrafish and rats. In terms of obesity, the overfed zebrafish had significantly higher body mass when compared to lean fish confirming successful execution of the overfeeding protocol. Overfeeding did not impact ROS, however there was a decrease in VE-cadherin expression in the zebrafish dorsal aorta, pointing to a cumulative effect of DTG and obesity (overfeeding). Conclusion: This study suggests that in the absence of HIV, DTG does not have an effect on redox status and endothelial dysfunction in terms of tight and adherens junction integrity. However, the addition of overfeeding highlighted the cumulative effect of DTG and obesity on endothelial function, an effect that can potentially impact the human population.
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    The role of estrogen receptors in fibrosis: in search of therapeutics
    (Stellenbosch : Stellenbosch University, 2024-02) Alberts, Janneke; Smith, Carine; Ollewagen, Tracey; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Medicine. Division of Clinical Pharmacology.
    ENGLISH ABSTRACT: Background: Autoimmune rheumatic diseases, affecting 5-8% of people globally, exhibit a 2:1 female prevalence bias, influencing severity and prognosis. Chronic inflammation leads to immune complex formation, which causes vessel occlusion, and resulting in fibrosis, contributing to cardiovascular diseases, particularly myocarditis. Fibrosis - driven by activated fibroblasts - results from extracellular matrix dysregulation, causing tissue scarring and organ dysfunction. Therefore, investigating antifibrotic interventions is crucial for global healthcare. 17β-estradiol (E2), the predominant female hormone, has the potential to modulate fibrosis, but literature in this niche is contradictory. Zebrafish have been identified as an ideal model for studying sex bias in autoimmune rheumatic-related myocarditis, exploring the role of E2 in chronic inflammation and fibrosis. Methods: To elucidate underlying mechanisms, a multidisciplinary approach was imperative. Employing diverse model systems, the thesis incorporated two pilot studies. The initial pilot study utilised male human dermal fibroblasts (HDFs) in vitro to assess the impact of E2 on cell function linked to fibrotic outcome. Cell viability and fibronectin production were assessed after 24 hours (h) E2- exspoure relative to that of untreated cells. Subsequently, a second pilot study evaluated behavioural outcomes in larval zebrafish, in response to exposure of a range of E2 dosages for 60 h, informing the selection of an appropriate, potentially beneficial, E2 concentration for the main experiment. A significant innovation was the establishment of a novel larval zebrafish myocarditis model, by means of microinjection with a sclerosing agent (bleomycin). Using this model, the effect of added E2 and modulation of estrogen receptor (ER) signalling on fibrosis was determined by staining for collagen (Masson-Goldner Trichrome) and vimentin (immunofluorescence staining). Results: Results generated in HDFs elucidated that treatment with E2 did not significantly alter the fibroblast viability or fibronectin production. Microinjected zebrafish larvae exhibited lower basal activity levels than controls (p