4. Electronic Theses and Dissertations (ETDs) - Faculties submissions
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Item Immunomodulation of the innate immune system: The role of vitamin D in the context of monocytes and macrophages(University of the Witwatersrand, Johannesburg, 2024-07) Mol, Bronwyn Ashleigh; Gentle, Nikki; Meyer, VanessaMacrophages are widely distributed cells of the innate immune system with essential roles in homeostasis and disease. Despite concerted efforts, several aspects of macrophage origin, biology, and functionality remain poorly understood. To gain a deeper understanding of these cells, a physiologically relevant, but practical model is required. In vitro, macrophages are principally generated from primary monocytes and monocyte-like cell lines through a natural process referred to as monocyte-to-macrophage differentiation. Monocyte-like cell lines have several practical advantages over the use of primary monocytes with the most commonly employed monocyte-like cell lines being THP-1 and U937 cells. Despite their frequent use, no standardised protocol is employed in the differentiation of monocyte-like cell lines to macrophages. Naturally, this results in large discrepancies and a lack of comparability between studies. Furthermore, many of these protocols are not physiologically relevant and produce macrophages that are not responsive to downstream stimuli. 1,25-dihydroxyvitamin D3 (1,25(OH)2D3), the biologically active form of vitamin D3, is a recognised immunomodulator that shows pronounced genomic and non-genomic effects in immune cells. It is also reported as an inducer of monocyte-to-macrophage differentiation, though heavily debated, and a potential macrophage polarisation agent. Despite this, there is relatively little information concerning the role of 1,25(OH)2D3 in monocyte-to-macrophage differentiation and macrophage biology. This study aimed to develop a more physiologically relevant differentiation protocol for the monocyte-like THP-1 and U937 cell lines. This model was then used to investigate the role of 1,25(OH)2D3 in monocyte-to-macrophage differentiation and macrophage biology. Assessment of morphological features and the macrophage markers, CD11b and CD14, indicated that in both THP-1 and U937 cells, differentiation induced using a combination of 5 nM of phorbol 12-myristate 13-acetate (PMA) and 10 nM 1,25(OH)2D3 over 96 hours produced the most mature macrophages. It was observed that 1,25(OH)2D3 alone was not capable of inducing differentiation, yet when combined with PMA, greatly enhanced macrophage features. THP-1 cells are the most widely employed monocyte-like cell line, and are proposed to be the most reflective of primary monocytes. In this study these cells were shown to be more responsive to the effects of 1,25(OH)2D3 than their U937 counterparts. As such, RNA-sequencing was used to explore the efficacy of the proposed differentiation protocols and the influence of 1,25(OH)2D3 on macrophage biology in THP-1 cells. Differential gene expression analysis confirmed that the most effective differentiation protocol was the combination of 5 nM PMA with 10 nM 1,25(OH)2D3 when considering macrophage associated features including transcription factor usage, adhesion, phagocytosis, and cytokine and cytokine receptor expression. This protocol also produced THP-1-derived macrophages that showed increased expression of genes considered to be primary macrophage markers. These results also suggested that THP-1 cells differentiated with neither PMA nor PMA with 1,25(OH)2D3 were likely to represent fully polarised macrophages. 1,25(OH)2D3 treatment of THP-1 monocytes and THP-1-derived macrophages produced distinct gene expression profiles with considerably less overlap than expected. Though 1,25(OH)2D3 treatment often affected similar biological processes in both cell types, the genes within these processes found to be differentially expressed in each cell line were often distinct. For example, in THP-1- derived macrophages, but not THP-1 monocytes, 1,25(OH)2D3 treatment resulted in the increased expression of genes encoding numerous antibacterial peptides, several small GTPases and their regulators. Additionally, several type I interferon response related proteins showed decreased expression, while expression of cytokines and cytokine receptors was variable. This, taken together with the morphological work, indicates two potential roles for 1,25(OH)2D3 in macrophages. Firstly, a protective role as it suggests the potential to prime an antibacterial response, while still balancing inflammatory responses and protecting against autoinflammation induced by aberrant type I interferon response. Secondly, a potential role in determining the morphological features, clearly demonstrated through microscopy, and further suggested by the differential expression of a variety of small GTPases and their regulators.Item Detecting Disease in Citrus Trees using Multispectral UAV Data and Deep Learning Algorithm(University of the Witwatersrand, Johannesburg, 2024-06) Woolfson, Logan Stefan; Adam, ElhadiThere is a high prevalence, in South Africa, of fruit tree related diseases infesting lemon trees, subsequently affecting overall crop yield and quality. Ultimately, the income for the farmers is significantly diminished and limits the supply of nutritional food crops for the South African population, who already suffer from a high incidence of malnutrition. Currently, there are various methods utilized to detect diseases in fruit trees, however they pose limitations in terms of efficiency and accuracy. By employing the use of drones and machine learning methods, fruit tree diseases could be detected at an earlier stage of development and with a much higher level of accuracy. Consequently, the chances of remedying the trees before the disease spreads is greatly improved, and the supply of nutritious fruit within South Africa is increased. This research report’s aim is to investigate the effectiveness of a deep learning algorithm for detecting and classifying diseases in lemon orchards using multispectral drone imagery. This entails assessing the performance of a pretrained ResNet-101 model, fine-tuned with additional sample images, in accurately identifying and classifying diseased lemon trees, specifically those affected by Phytophthora root rot. The methodology involves the utilization of a pretrained ResNet-101 model, a deep learning architecture, and the retraining of its layers with an augmented dataset from multispectral aerial drone images of a lemon orchard. The model is fine-tuned to enhance its ability to discern subtle spectral variations indicative of disease presence. The selection of ResNet-101 is grounded in its proven success in image recognition tasks and transfer learning capabilities. The results obtained demonstrated an impressive accuracy of 80%. The deep learning algorithm exhibited notable performance in distinguishing root rot-affected lemon trees from their healthy counterparts. The findings indicate the promise of utilizing advanced deep learning methods for timely and effective disease detection in agricultural farmlands, facilitating orchard management.Item Knockdown of long non-coding RNA PANDA improves the cytotoxic effects of cisplatin in oesophageal squamous cell carcinoma cell lines(University of the Witwatersrand, Johannesburg, 2024-11) Moonsamy, Sasha Sarasvathee Keshnee; Mavri-Damelin, Demetra; Jivan, RupalOesophageal cancer is one of the leading causes of cancer death worldwide, of which oesophageal squamous cell carcinoma (OSCC) is the major subtype in southern and eastern Africa. Cisplatin is a well-established drug used to treat multiple cancers, including OSCC. Drug resistance is a major impediment to continued cisplatin therapy in numerous cancers. LncRNA P21-associated non-coding RNA DNA damaged activated RNA (PANDA) is known to function in cell cycle regulation in response to DNA damage and is upregulated in OSCC. We aim to determine lncRNA PANDA expression in South African-derived OSCC cells and establish whether down-regulation of this lncRNA can be used to supplement cisplatin therapy. In this study, MTT assays were performed to determine the EC50 concentrations of cisplatin in OSCC (WHCO1, WHCO5, and SNO) cells and HEK293 cells as a non-cancer control. The cytotoxic effects of cisplatin were exerted in all cell lines, with WHCO5 and SNO appearing more responsive to cisplatin than WHCO1 and HEK293. RT-PCR was used to detect if lncRNA PANDA is expressed in untreated and cisplatin-treated cells and was detected in all cell lines. Knockdown of lncRNA PANDA by siRNA was assessed with RT-PCR. Phase contrast microscopy was used to assess whether siRNA reagents altered cell morphology at 5, 24, and 48 hours post treatment. No significant alterations in cell morphology were observed in WHCO1, WHCO5, SNO, and HEK293 cells. MTT assay evaluation after 48 hours of cisplatin exposure, with or without siRNA for lncRNA PANDA, showed a significant reduction in EC50 concentrations in WHCO5, SNO, and HEK293 cell lines, suggesting that knockdown of lncRNA PANDA may improve cisplatin cytotoxicity in some cell lines. However, the EC50 values were higher with lncRNA PANDA knockdown in the WHCO1 cell line, suggesting that not all OSCC cell types may be responsive to this approach. In conclusion, lncRNA PANDA is expressed in response to cisplatin-induced DNA damage, and the down regulation of lncRNA PANDA improves the cytotoxic effects of cisplatin; however, further investigations are warranted in OSCC.Item Novel antiangiogenic peptide targeted therapeutic nanosystem for non-small-cell lung carcinoma(University of the Witwatersrand, Johannesburg, 2023) Ngema, Lindokuhle Malibongwe; Choonara, Yahya Essop; Marimuthu, Thashree; Adeyemi, AdebawoleLung cancer is the leading cause of cancer deaths globally, with nearly 1.8 million deaths and 2.2 million incidences recorded annually. Primarily, non-small-cell lung carcinoma (NSCLC) is the most commonly diagnosed type of lung cancer, which makes up approximately 85% of all reported lung cancer cases. Currently, the management of NSCLC is a global challenge, and although, various treatment protocols are available, such as surgery, radiotherapy, and chemotherapy, the survival outcomes remain poor. Combination chemotherapy is the current first-line treatment for NSCLC, however, it presents with a myriad of drawbacks, including non-specificity, high dosage, and detrimental side effects, resulting in patients intolerability to the regimen. Consequently, a new therapeutic approach is greatly needed and warrants the design of biocompatible targeted drug delivery nanosystems that can halt tumor proliferation and metastasis by targeting key molecules and deliver drugs directly to tumors, with limited side effects and toxicity to healthy cells. Tumor targeted drug delivery nanosystems such as magnetic nanoparticles (MNPs) modified with biomolecules and functionalized with homing peptides are of great interest for potential application as a potent nanomedicine in NSCLC management. Accordingly, the present study set to develop novel targeted paclitaxel (PTX) delivery nanosystems from the amenable superparamagnetic iron oxide nanoparticles (SPIONs) coated with trans-10,cis-12 conjugated linoleic acid (10E, 12Z) and functionalized with either a vascular endothelial growth factor receptor (VEGFR) binding or a matrix metalloproteinase 2 (MMP-2) binding peptide, for specific delivery of PTX to VEGFR and MMP-2 expressing NSCLC tumors. A preceding nanosystem without the peptides (CLA-coated PTX-SPIONs) was originally fabricated as proof of concept for the application of 10E, 12Z CLA as a surface coating and drug partitioning biomolecule. CLA-coated PTX-SPIONs exhibited a spherical shape, with an average particle size and zeta potential of 96.5 ± 0.6 nm and −27.3 ± 1.9 mV, respectively. The nanosystem had a drug loading efficiency of 98.5% and demonstrated a sustained site-specific in vitro release of PTX over 24 h (i.e., 94% at pH 6.8 mimicking the tumor microenvironment). Enhanced anti-proliferative activity was also observed with the CLA-coated PTX-SPIONs against a lung adenocarcinoma (A549) cell line after 72 h, with a recorded cell viability of 17.1%. Thereafter, the fabricated nanosystem was optimised for direct tumor-targeting by functionalization with HRH or CTT peptides, to give CLA-coated PTX-SPIONs@HRH and CLA-coated PTX-SPIONs@CTT. A new design methodology was established for the tandem surface functionalization of CLA-coated PTX-SPIONs with the antiangiogenic peptides, via coupling reactions. A series of robust nanotechnological techniques were employed for pertinent physicochemical characterization, in vitro evaluation of drug release, anti-proliferative activity, and quantification of VEGF-A and MMP-2 levels. Meanwhile, in vivo testing was carried out on a lung tumor xenograft mouse model. Both nanosystems exhibited a marked cellular uptake and internalization by A549 cells, and CLA-coated PTX-SPIONs@HRH significantly reduced secretion levels of VEGF-A in human dermal microvascular endothelial cells (HMEC-1) from 46.9 pg/mL to 35.6 pg/mL, meanwhile CLA-coated PTX-SPIONs@CTT significantly inhibited MMP-2 secretion by almost 70% , indicating specific anti-MMP-2 activity. A 76.6% and 69.7 % tumor regression was observed in a lung tumor xenograft mouse model treated with CLA-coated PTX SPIONS@HRH and CLA-coated PTX-SPIONs@CTT, respectively, demonstrating tumor targetability and angiogenesis inhibition. Lastly, the pharmacokinetics (PK) evaluation revealed that both nanosystems prolonged the half-life of PTX and circulation time in vivo. In essence, potent antiangiogenic tumor-targeted PTX delivery nanosystems were successfully fabricated, and the obtained results suggest potential application of CLA-coated PTX SPIONs@HRH and CLA-coated PTX-SPIONs@CTT for effective management of NSCLC.Item Optimising laboratory-rearing parameters for anopheles funestus to enhance scalability toward the sterile insect technique(University of the Witwatersrand, Johannesburg, 2023-11) Niain’ny Felamboahangy, Lalasoa; Koekemoer, Lizette; Munhenga, Givemore; Kaiser, MariaThe plateauing of gains in the fight against malaria, partly due to insecticide resistance in malaria vector mosquitoes, is a threat to malaria control. Additional vector control tools like the sterile insect technique (SIT) are being evaluated. Anopheles funestus, a main malaria vector in Africa, has not yet been evaluated for control using SIT partly due to difficulties in its colonisation. To proceed with SIT for this species, knowledge of their optimal laboratory-rearing conditions is critical. To optimise An. funestus laboratory-rearing conditions, this study investigated the effect of using an artificial blood-feeding system or anaesthetised guinea pig on fecundity and fertility. Different larval diet doses and larval rearing densities were determined using a life-table approach. Finally, a range of irradiation doses were used to determine the optimal dose which induces sterility in An. funestus males without impacting the ability of the sterile males’ to compete with fertile males to mate with fertile females. Subsequently, mating competitiveness under laboratory conditions of An. funestus males irradiated at 120 Gy across three different ratios of fertile: irradiated males were performed. Results showed that fecundity was three times higher in females blood-fed on anaesthetised guinea pig compared to those blood-fed on the artificial blood-feeding system using bovine blood. Increasing the blood-meal frequency using the artificial blood-feeding system increased egg production, although it was not statistically significant. There were no significant differences between the egg fertility from females that fed on guinea pig or those fed on the artificial blood-feeding system using bovine blood. Anopheles funestus larvae fed with a food dose of 0.04 mg/larva and reared at a density of 0.48 larvae/cm2 resulted in optimal developmental time and pupal production. Furthermore, irradiation of male pupae at different doses did not affect adult emergence regardless of the dose used, however, it correlated negatively with longevity and fertility. Irradiation at doses greater than 100 Gy resulted in a significant difference in both fecundity and fertility. The average mating competitiveness value of An. funestus males irradiated at 120 Gy was 1.24, decreased from 2.63 to 0.27 for different ratios of sterile male: fertile male: fertile female 1:1:1 to 3:1:1. In conclusion, these findings can be used to improve the rearing of An. funestus under laboratory conditions, improving evaluations for SIT. Feeding defibrinated bovine blood through an artificial system will reduce the dependency on live animals for blood-feeding. Optimised larval feeding and rearing density will reduce developmental time and ensure maximal pupal production. An irradiation dose of 100 Gy can be used to induce sterility of An. funestus without significantly affecting mating competitiveness.Item Investigation of Contamination of Community Groundwater Sources with Antibiotics in Informal Settlements of Kisumu, Kenya(University of the Witwatersrand, Johannesburg, 2023-09) Karimi, Kellen Joyce; Ahmad, Aijaz; Duse, Adriano; Mwanthi, MutukuAntibiotics have been used to cure diseases, but there are growing concerns about the risk to human health caused by inadvertent exposure to low levels of antibiotics in the environment. Despite extensive reporting from the developed world on antibiotic pollution of groundwater, relatively little study has been conducted on antibiotic contamination of groundwater in the developing countries, particularly informal settlements. Antibiotic usage and misuse have long been seen as clinical events, with little understanding of the role of disposal in the development of environmentally induced resistance. Exposure pathways that contribute to groundwater contamination in informal settlements put residents at odds because they already face inequalities, such as a high disease burden exacerbated by antibiotic resistance; thus, proper antibiotic disposal is critical in protecting human and environmental health. The purpose of this cross-sectional study was to establish the prevalence of groundwater contamination with the common antibiotics’ such as sulfamethoxazole, trimethoprim, and metronidazole, and the related antibiotic resistance and the human health risk of exposure. Ethical clearance to conduct research was obtained from three institutions as follows: - the Health Research Ethic Committee of the university of the Witwatersrand (HREC. Protocol Number M190412); the Kenyatta National Hospital and University of Nairobi Ethics and Research Committee (KNH/UoN-ERC. Ref No. P71910/2018); and the National Commission for Science, Technology, and Innovation (Ref No. NACOSTI/P/19/3232/28732). Each respondent gave informed consent to participate in the study. Anonymity was maintained at all levels of the study to protect the study participants from identification. Antibiotic use, which is connected to antibiotic disposal, was evaluated in a random sample of 447 families. From the 188 mapped groundwater sources, a random sample of 49 groundwater sources was chosen, and water samples were taken for antibiotic concentration analysis utilising a solid-phase extraction and liquid chromatography coupled to magnetic sector high resolution mass spectrometry (SPE-LC-MS/MS). The Kirky-Bauber diffusion method was used to test antibiotic resistance in Escherichia coli. The community's potential groundwater contamination routes were assessed by determining antibiotic use and disposal among households as well as assessing the environmental risk of exposure. In the households visited, 75% (n=337) were female and 25% (n=110) were male. The prevalence of antibiotic use in informal settlements was 43% (n=193), with 70% (n=137) users reporting that they obtained the antibiotics through a prescription from a health practitioner. A significant relationship was observed between having HIV/AIDS and acquiring antibiotics through a prescription; p=0.001. An association was also observed among the informal settlements, where a lower number of MNY B dwellers did not receive a prescription for the antibiotics acquired. There was no statistically significant difference in antibiotic use between males and females; odds ratio=1.33; whereas there was a difference in HIV/AIDS status; odds ratio=0.313; and among informal settlements where the odds of using antibiotics were reduced in NY B; odds ratio=0.42. Respondents who used antibiotics either kept the unused antibiotics for future use 87.1% (n=27) or disposed them. Among the disposals 51.6% (n=16) disposed in pit latrines, 16.1% (n=5) dispose in compost pits, and 6.5% (n=2) dispose the remaining antibiotics by burning. Females completed their antibiotic doses at a higher rate (36.3%; n=117) than males (32.5%; n=39). Significant difference was observed in completion rate among the HIV/AIDS positive and negative respondents as well as among informal settlements; p<0.000 and p=0.001 respectively. On the other hand, groundwater use in these communities is widespread. Respondents used it for a variety of purposes, including drinking (9%; n=39), though they declined to report. Awareness of the health consequences of drinking antibiotic-contaminated water was also low (35%; n=158), especially among households that reported antibiotic use; p=0.003. Only Sulfamethoxazole was detected in 7 out of 49 groundwater samples at a detection frequency of 14.3%; with concentrations ranging from nd to 258 ng/L. Escherichia coli and Cryptosporidium parvum were isolated from all the 49 water samples and E. coli isolates from 3 (6%) water samples were resistant to sulfamethoxazole with Inhibition Zone Diameters of 0.8 mm, 10.5 mm, and 11.5 mm. The 3 water samples were however not among samples where sulfamethoxazole was detected. The Hazard Quotient was 0 (zero), and therefore no risk of exposure to sulfamethoxazole in the environment, but the level of antibiotics that trigger antibiotic resistance is not known. Because of the rising problem of antibiotic resistance due to overuse and incorrect disposal, teaching on safe antibiotic prescription should be incorporated into medical training for all cadres. In addition to educating patients on proper use and disposal, the ministries of health should ensure the antimicrobial stewardship standards are adhered to both locally and worldwide. Follow-up research of antibiotic resistance discovered in three groundwater sources must be done to eliminate the possible sources and prevent further spread. This study is instrumental in informing the inclusion of antibiotics on the list of frequently monitored contaminants during water treatment, as well as serving as a starting point for antibiotic surveillance in Kenya.Item Exercise in Ghanaian, postmenopausal women with an increased body mass index (bmi), above 25 KG/M²(University of the Witwatersrand, Johannesburg, 2023-08) Bonsu, Isaac Mensah; Myezwa, Hellen; Corlia, Brandt; Ajidahun, Adedayo TundePostmenopausal women frequently experience weight gain in addition to an increased tendency for central fat distribution. The development of metabolic syndrome and systemic inflammation caused by excess body weight (overweight and obesity), particularly in the form of visceral fat deposition in postmenopausal women, increases the risk of cardiovascular disease, diabetes, and mortality. The reported high prevalence of excess weight among Ghanaian postmenopausal women generated an inquiry into the experiences of postmenopausal women with excess weight gain. This study aimed to develop and test the effect of a culturally adapted exercise-based programme for weight loss in Ghanaian postmenopausal women. The study used a mixed-method approach with five studies to address the study's aim. A quantitative study was conducted to determine the prevalence of excess weight gain and associated socio-demographic risk factors among postmenopausal women. The results showed a high prevalence of excess weight gain of 73.2%, 91.8%, and 91.0% using body mass index (BMI), waist-to-height ratio (WHtR) and waist-to-hip ratio (WHR) respectively among 378 women. Education and ethnicity were the predictors of excess weight gain (WHR) among the participants. Despite the extensive body of research on an exercise program for weight loss, these results suggest gaps in weight management. Physical activity, lifestyle, and sociocultural levels of the women were investigated quantitatively to determine contributing factors associated with the high prevalence of excess weight gain. The results showed that the majority (55.2%) of the participants had 1 to 2 days per week of moderate physical activities for 1 to 20 minutes per day during the last 7 days. This finding showed that participants are not meeting the physical activity recommendation of 150-300 minutes of moderate-intensity per week for older adults by World Health Organization (WHO) guidelines on physical activity and sedentary behaviour. Housewives and unemployed participants had a higher risk of weight gain, especially when assessed with WHR and WHtR. Most participants (59.7%) had poor eating habits and cultural beliefs regarding body size impacts their decisions regarding weight loss. A qualitative study was conducted with the study group of postmenopausal women with excess weight, twenty-four participants, and four focus group discussions (FGD), to explore their current weight management approaches or practices. From the analysis of FGD, three major themes emerged from the study namely, (i) perception of body weight, (ii) measures to reduce body weight, and (iii) support for adherence to the weight management program. Sub-theme under the perception of body weight revealed that weight gained was viewed as the presence of diseases and admired by society as a culturally accepted body image. Diet-related changes, a combination of diet modification and physical activity, and weight management supplements emerged as measures to reduce excess weight. Support for adherence to the weight program included health education, access, affordable exercise facilities, and social support. Based on literature reviews and findings from the three studies conducted as part of the project, a culturally appropriate exercise programme for weight loss was developed and validated by the Delphi study. A Delphi consists of three rounds among international (twelve) and local (twenty-one) experts with a high participation rate of 33 (80.5%) of the 41 participants was conducted. A consensus was reached on all the thirty-two (32) items related to health assessment, pre-exercise parameters, exercise dosage and physician referral after the third round. The developed culturally informed exercise-based weight loss programme was tested using a single-blind randomized controlled trial. A total of 226 postmenopausal women were randomized into exercise (113) and control (113). Anthropometrics (BMI, WHR, WHtR WC, HC and body weight) and body composition (body fat, visceral fat, muscle mass) were measured pre and post-12-week intervention. Using a repeated-measures linear mixed model, the evidence from the analysis demonstrates that except for waist-to-hip ratio (WHR), there were statistically significant reduction in body weight, BMI, WHtR, visceral fat, and total body fat in the exercise and control groups. Muscle mass increased significantly (+0.21 kg), whereas hip circumference (-2.46 cm) and waist circumference (-1.39 cm) decreased significantly compared with the control group. Within the exercise group when stratified by BMI, there were higher reductions in BMI (1.01kg/m2 vs. 0.46kg/m2), WC (2.18cm vs. 0.22cm), body weight (2.12kg vs. 1.17kg) and body fat (1.84% vs 1.6%) in obese women compared to overweight women. Weight loss programmes should be traditionally induced within the specific setting to encourage full participation and reduce the dropout rate. Implication for health professionals to prescribe physical activity in postmenopausal women’s treatment plan. In conclusion, the findings resulting from this research may improve health providers' cultural awareness and knowledge. This project is expected to help healthcare professionals improve the care given to postmenopausal women with weight excess to decrease the incidence of morbidity and mortality. It is anticipated that this initiative could direct the development of a modified culturally-sensitive weight loss programme for women in different stage in life and use with other ethnic groups.Item Prevalence and factors of HIV associated Oral Kaposi Sarcoma at Wits Oral Health Centre, Johannesburg(University of the Witwatersrand, Johannesburg, 2024-07) Chetty, Hasita; Padayachee, Sankeshan; Mafojane, TumaneIntroduction: HIV associated Oral Kaposi Sarcoma (OKS) is a neoplasm predominantly occurring in immunocompromised patients. Therefore, it is often observed in an HIV positive and AIDS population (Moore & Chang, 2003). KS is caused by the Kaposi Sarcoma Herpes Virus (KSHV) or Human Herpes Virus-8 (HHV8) (Naidoo et al, 2016). The risk of acquiring KS increases in the presence of HIV infection and immunosuppression (Kamulegeya & Kalyanyama, 2008). HIV-KS can occur at any stage of HIV infection but has been more prevalent at the stage of AIDS or severe immune impairment (Khammissa et al., 2012). Both HHV8 infection and HIV/AIDS are highly prevalent in Africa (Kamulegaya and Kalyanyama, 2008). There is a lack of current evidence documenting the relationship between HIV/AIDS and OKS since the implementation of ART, therefore this study intends to augment the existing literature. This study aimed to determine the prevalence and factors of HIV associated OKS, on histopathologically diagnosed patients attending the WITS Oral Health Centre, Johannesburg, between 2008 and 2018. This period predates and postdates the roll out of ART in the South African public health sector in 2012 and speaks to the relationship between ART and the occurrence of HIV associated OKS. Materials and Method: This is a cross-sectional study using records from the Wits Oral Health Centre (WOHC) and National Health Laboratory Service (NHLS). The study period is 10 years from January 2008 to December 2018. Prevalence of OKS was calculated based on patients with a positive histopathological diagnosis of OKS within the study period from the NHLS database. Ethical Considerations: Permission was requested from the Academic Affairs and Research Management System (AARMS) National Health Laboratory Service (NHLS) and WOHC to access patient files. Records of patients with a positive OKS histopathological diagnosis were noted. They were allocated a study number and patient number on a data sheet. The corresponding patients’ files were accessed from WOHC to attain further information (as per the data sheet). Patient confidentiality was be maintained as no names were recorded and files were allocated a number for cross-referencing between NHLS and WOHC data. Ethics clearance was attained from the Wits Human Research Ethics Committee to carry out this study. Results: The prevalence of OKS that was found in this population (137679 patients seen at WOHC) was 0.017432%(n=24). There were more females that presented with OKS than males. The mean age of presentation was 39.11 years of age (SD 12.459). There was a significant relationship between high viral loads and a low CD4 count. The palate was the site most frequently biopsied in diagnosed OKS cases. Conclusion: The prevalence of OKS over the study period was very low. The mean age of OKS presentation was 39.21 years of age. More females presented with HIV associated OKS than males and the palate was the site, from which most biopsy samples were taken in OKS diagnoses. There is a significant relationship between high viral loads and low CD4 cell counts. This study is suggestive that a possible reason for the low number of OKS cases could be administration of ART by state institutions in South Africa, this can be further investigated to establish the effect of ART on OKS.Item Occupational exposure to chemicals, and health outcomes, among nail technicians in Johannesburg, South Africa(University of the Witwatersrand, Johannesburg, 2023-08) Keretetse, Goitsemang; Brouwer, Derk H.; Nelson, GillIntroduction: Nail technicians are exposed to chemicals emitted from activities performed in nail salons, including simple buffing of nails, basic manicures and pedicures, application of nail polish, and the application and sculpting of artificial nails. The various products used during these processes may contain volatile organic compounds (VOCs), which pose a health risk to both the nail technicians and their clients. Associated health effects include skin, eye, and respiratory irritation, neurologic effects, reproductive effects, and cancer. The aim of this study was to effects within the formal and informal sectors in Johannesburg, South Africa. In this study, informal nail technicians are defined as those working in nail salons that are not licensed or registered with any formal enterprise or establishment, or in their own capacity. The objectives were 1) to estimate the prevalence of self-reported symptoms associated with the use of nail products, 2) to measure exposures to chemicals in nail products used in the formal and informal nail salons, 3) to investigate the feasibility and reliability of self-assessment of exposure as a method of estimating exposure to chemicals, and 4) to investigate the association between respiratory symptoms (chronic and acute) and chemical exposures in both formal and informal nail technicians. Methods: This was a cross-sectional study. A questionnaire, adapted from other studies, was piloted before being administered to the participating nail technicians. Data were collected from 54 formal and 60 informal nail technicians, regarding sociodemographic characteristics, perceptions of working with nail products, and self-reported symptoms of associated health effects. A subset of 20 formal and 20 informal nail technicians was conveniently selected from the 114 participants for the exposure assessment phase. The two groups were further divided into two groups of 10 for the controlled/expert exposure assessment (CAE) and the self-assessment of exposure (SAE). Personal 8-hr exposure measurements were performed using VOC and formaldehyde passive samplers attached to the participant’s breathing zone over three consecutive days. For the SAE approach, participants conducted their own exposure measurements, while the CAE approach was fully conducted by the principal researcher. Task-based measurements were carried out using a photoionization detector (PID) to measure peak concentrations during specific nail application activities. A probabilistic risk assessment was conducted to estimate the carcinogenic and non-carcinogenic life time risks from exposure to VOCs. Chemical analysis was conducted by a SANAS-accredited laboratory. After correcting for their respective evaporation rates, relative to the evaporation rate of d-limonene (the VOC with the lowest evaporation rate), the adjusted total VOC (TVOC) concentrations were calculated using the 13 VOCs that were detected at a frequency of 30% or more. VOC concentration data below the limit of detection (LoD) were imputed, using the regression on order statistic (Robust ROS) approach. The self-reported symptoms were categorised into neurological effects, respiratory effects, eye irritation, and skin irritation. The ACGIH additive effects formula was used to calculate the combined respiratory effect of selected VOCs. Different statistical tools were used to analyse the data for each objective. Results: Formal and informal nail technicians used different nail products, performed different nail applications, serviced different mean numbers of clients, and were exposed to different concentrations of selected VOCs. Acetone concentrations were higher in formal nail salons, due to the soak-off method used for removing existing nail applications, while methyl methacrylate (MMA) concentrations were higher in informal nail salons - related to acrylic methods being used more frequently in the informal than the formal nail salons. All VOC concentrations were below their respective occupational exposure limits, with the exception of formaldehyde (0.21 mg/m3). TVOC levels were higher in formal nail salons, due to the bystander effect from multiple nail technicians performing nail applications simultaneously. Sixty percent of the informal nail technicians reported health-related symptoms, compared to 52% of the formal nail technicians, and informal male nail technicians reported more symptoms than their female counterparts. All nail technicians' median and 95th percentile non-cancer risks exceeded the acceptable risk of 1 for xylene, 2-propanol, and benzene, while the cancer risk estimates (medians and 95th percentiles) for benzene and formaldehyde exceeded the US EPA cancer risk threshold of 1 x 10-6. Conclusion: This is the first study to assess exposures to VOCs in the often-overlooked informal sector and compare these exposures with those in the formal sector of the nail industry. Personal breathing zone concentration data for nail salon workers were generated in this study, including the informal sector, which is always challenging to access for research. Although banned in many countries, MMA is still used in South Africa in the informal nail sector. The SAE study showed that participatory research is feasible and enables a more reliable estimate of the exposure by expanding the amount of data. Using a combination of shift and task-based measurements was particularly effective in creating exposure profiles of employees and identifying activities that require targeted interventions. There is a need for the nail industry, especially the informal salons, to be more closely regulated, concerning the hazardous chemicals frequently encountered in nail products. Nail salons should reduce exposure frequency by regulating working hours, making informed decisions regarding the procurement of nail products, and adopting safe work practices to reduce emissions from harmful chemicals and thus exposure among nail salon workers and their clients.Item Preventing Coal Mine Dust Lung Disease: Application of Bayesian Hierarchical Framework for Occupational Exposure Assessment in The South African Coal Mining Industry(University of the Witwatersrand, Johannesburg, 2023-10) Made, Felix; Brouwer, Derk; Lavoue, Jerome; Kandala, Ngianga-BakwinBackground: The world's largest energy source is coal with nearly 36% of all the fuel used to produce power. South Africa is the world's top exporter and the seventh-largest producer of coal. In the upcoming years, it is expected that South Africa's coal production output rate will rise. Coal mine dust lung disease (CMDLD) is an irreversible lung disease caused by the production of coal, the emission of dust, and prolonged exposure to the dust. When conducting safety evaluation, exposure is typically reported as an eight-hour time-weighted average dust concentration (TWA8h). In occupational exposure contexts, occupational exposure limits (OEL) are often used as a threshold where workers can be exposed repeatedly without adverse health effects. The workers are usually grouped into homogenous exposure groups (HEGs) or similar exposure groups (SEGs). In South Africa, a HEG is a group of coal miners who have had similar levels and patterns of exposure to respirable crystalline silica (RCS) dust in the workplace. Several statistical analysis methods for compliance testing and homogeneity assessment have been put into use internationally as well as in South Africa. The international consensus on occupational exposure analysis is based on guidelines from the American Industrial Hygiene Association (AIHA), the Committee of European Normalisation (CEN), and BOHS British and Dutch Occupational Hygiene Societies' guidelines (BOHS). These statistical approaches are based on Bayesian or frequentist statistics and consider the 90th percentile (P90) and 95th percentile (P95), with- and between-worker variances, and the lognormal distribution of the data. The current existing practices in South Africa could result in poor or incorrect risk and exposure control decision-making. Study Aims: The study aimed to improve the identification of coal dust overexposure by introducing new methods for compliance (reduced dust exposure) and homogeneity (similar dust exposure level) assessment in the South African coal mining industry. Study Objectives: The objectives of this study were: 1. To compare compliance of coal dust exposure by HEGs using DMRE-CoP approach and other global consensus methods. 2. To investigate and compare the within-group exposure variation between HEGs and job titles. 3. To determine the posterior probabilities of locating the exposure level in each of the OEL exposure categories by using the Bayesian framework with previous information from historical data and compare the findings and the DMRE-CoP approach. 4. To investigate the difference in posterior probabilities of the P95 exposure being found in OEL exposure category between previous information acquired from the experts and the current information from the data using Bayesian analysis. Methods: The TWA(8h) respirable coal dust concentrations were obtained in a cross-sectional study with all participants being male underground coal mine workers. The occupational hygiene division of the mining company collected the data between 2009 and 2018. The data were collected according to the South African National Accreditation System (SANAS) standards. From the data, 28 HEGs with a total of 728 participants were included in this study. In objectives 1 and 2, all 728 participants from the 28 HEGs were included in the analysis. For exposure compliance, the DMRE-CoP accepts 10% exceedance of exposure above the OEL (P90 exposure values from HEGs should be below the OEL). The 10% exceedance was compared to the acceptability criterion from international consensus which uses 5% exceedance above the OEL (P95 exposure is below the OEL) of the lognormal exposure data. For exposure data to be regarded as homogenous, the DMRE-CoP requires that the arithmetic mean (AM) and P90 must fall into the same DMRE-CoP OEL exposure category. The DMRE-CoP on assessment of homogeneity was also compared with the international approaches which include the Rappaport ratio (R-ratio) and the global geometric standard deviation (GSD). A GSD greater than 3 and an R-ratio greater than 2 would both indicate non-homogeneity of the exposure data of a HEG. The GSD and DMRE-CoP criteria were used to assess the homogeneity of job titles exposure within a HEG. In objective 3 a total of nine HEGs which have 243 participants, were included in the analysis. To investigate compliance, a Bayesian model was fitted with a Markov chain Monte Carlo (MCMC) simulation. A normal likelihood function with the GM and GSD from lognormal data was defined. The likelihood function was updated using informative prior derived as the GM and GSD with restricted bounds (parameter space) from the HEGs' historical data. The posterior probabilities of the P95 being located in each DMRE exposure band were produced and compared with the non-informative results and the DMRE approach DMRE-CoP using a point estimate inform of the 90 percentiles. In objective 4, a total of 10 job titles were analysed and selected. The selection of the job titles was based on if they have previous year's data so it can be used to develop prior information in the Bayesian model. The same job titles were found across different HEGs, so to ensure the mean is not different across HEGs, the median difference of a job title exposure distribution across HEGs was statistically compared using the Kruskal-Wallis test, a non-parametric alternative to analysis of variance (ANOVA). Job titles with statistically non-significant exposure differences were included in the analysis. Expert judgements about the probability of the P95 located in each of the DMRE exposure bands were elicited. The IDEA (Investigate", "Discuss", "Estimate" and "Aggregate) expert elicitation procedure was used to collect expert judgements. The SHELF tool was then used to produce the lognormal distribution of the expert judgements as GM and GSD to be used as informative prior. A similar Bayesian analysis approach as in objective 3 was used to produce the probability of the P95 falling in each of the DMRE exposure bands. The possible misclassification of exposure arising from the use of bounds in the parameter space was tested in a sensitivity analysis. Results: There were 21 HEGs out of 28 in objectives 1 and 2 that were non-compliant with the OEL across all methods. According to the DMRE-CoP approach, compliance to the OEL, or exposure that is below the OEL, was observed for 7 HEGs. The DMRE-CoP and CEN both had1 HEG with exposures below the OEL. While the DMRE-CoP showed 6 homogeneous HEGs, however, based on the GSDs 11 HEGs were homogeneous. The GSD and the DMRE-CoP agreed on homogeneity in exposures of 4 (14%) HEGs. It was discovered that by grouping according to job titles, most of the job titles within non-homogenous HEGs were homogenous. Five job titles had AMs above their parent HEG. For objective 3, the application of the DMRE-CoP (P90) revealed that the exposure of one HEG is below the OEL, indicating compliance. However, no HEG has exposures below the OEL, according to the Bayesian framework. The posterior GSD of the Bayesian analysis from non-informative prior indicated a higher variability of exposure than the informative prior distribution from historical data. Results with a non-informative prior had slightly lower values of the P95 and wider 95% credible intervals (CrI) than those with an informative prior. All the posterior P95 findings from both non-informative and informative prior distribution were classified in exposure control category 4 (i.e., poorly controlled since exceeding the OEL), with posterior probabilities in the informative approach slightly higher than in the non-informative approach. Job titles were selected as an alternative group to assess compliance in objective 4. The posterior GSD indicated lower variability of exposure from expert prior distribution than historical data prior distribution. The posterior P95 exposure was very likely (at least 98% probability) to be found in exposure control category 4 when using prior distribution from expert elicitation compared to the other Bayesian analysis approaches. The probabilities of the P95 from experts' judgements and historical data were similar. The non-informative prior generally showed a higher probability of finding the posterior P95 in lower exposure control categories than both experts and historical data prior distribution. The use of different parameter values to specify the bounds showed comparable results while the use of no parameter space at all put the posterior P95 in exposure category 4 with 100% probability. Conclusions: In comparison to other approaches, the DMRE-CoP tend to show that exposures are compliant more often. Overall, all methods show that the majority of HEGs were non-compliant. The HEGs that suggest non-homogeneity revealed that the constituent job titles were homogenous. Application of the GSD criterion indicated that HEGs are more likely to be considered as homogeneous than when using the DMRE-CoP approach. When using the GSD and the DMRE-CoP guidelines, alternative grouping by specific job titles showed a greater agreement of homogeneity. The use of job titles showed that using HEGs following the DMRE-CoP current guidelines might not show high-exposure job titles and would overestimate compliance. Additionally, since job titles within a HEG may be homogeneous or have a different exposure to the parent HEG, exposure variability is not properly recorded when using HEGs. In compliance assessment, it is important to use the P95 of the lognormal distribution rather than the DMRE-CoP approach that use the empirical P90. Our findings suggest that the subgrouping of exposure according to job titles within a HEG should be used in the retrospective assessment of exposure variability, and compliance with the OEL. Our results imply that the use of a Bayesian framework with informative prior from either historical or expert elicitation may confidently aid concise decision making on coal dust exposure risk. Contrary to informative prior distribution derived from historical data or expert elicitation, Bayesian analysis using the non-informative uniform prior distribution places HEGs in lower exposure categories. Results from noninformative prior distributions typically show high levels of uncertainty and variability, so a decision on dust control would be reached with less confidence. The Bayesian framework should be used in the assessment of coal mining dust exposure along with prior knowledge from historical data or professional judgment, according to this study. For exposure, findings are to be reported with high confidence and for sound decisions to be reached about risk mitigation, an exposure risk assessment should be considered while using historical data to update the current data. The study also promotes the use of experts in situations where it is necessary to combine current data with historical data, but the historical data is unavailable or inapplicable.