A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in partial fulfillment of the requirements for the degree of Master of Science. Johannesburg, 1996. / Tobacco in Southern Africa has been found to exhibit three forms of leaf curl (class I, II and III) based on symptomology. Class I tobacco leaf curl is a disorder of unknown etiology, appearing as bent or twisted leaves exhibiting frilly enations (leafy outgrowths) along the midrib and secondary veins of severely stunted tobacco plants.[Abbreviated Abstract. Open document to view full version] / AC2017

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Introduction Bacterial vaginosis (BV) is a highly prevalent vaginal infection which poses a significant public health burden in Sub-Saharan Africa (SSA) due to its association with HIV, other STIs and several gynaecological and obstetrical complications. The aim of this study was to explore the underlying and proximate factors associated with BV and the relationships between them. Materials and Methods This study was a cross-sectional secondary analysis of the data collected during the Microbial Development Program (MDP) 301 trial. Logistic regression and structural equation modelling were used to test for the associations between BV and the explanatory variables and to test for the direct, indirect and total effects of the variables on BV. Results A total of 2 470 women were included in the analysis and of these 2 203 were aged 40 and below. The majority of them were unemployed at 72% and 51,8% were in the lowest socio-economic level. The baseline prevalence of BV was 40.5%. In the logistic regression, high socio-economic level (AOR=1.66; 95% CI 1.04-2.64) and using a condom during their last sexual encounter (AOR 0.82; 95% CI 0.69-0.97) were associated with BV infection. The STIs significantly associated with BV infection were: Herpes Simplex Virus 2 (HSV2) (AOR=1.31; 95% CI 1.10-1.56), trichomoniasis (AOR=2.68; 95% CI 1.97-3.64) and chlamydia infection (AOR 2.02; 95% CI 1.61-2.62). In the structural equation modelling (SEM) high socio-economic status had a positive direct effect on BV infection (beta=0.12, OR=1.14).Condom use during the last sex act had a negative direct effect on BV (beta=-0.043, OR=0.96). The presence of T.vaginalis, HSV2 or chlamydia infection had significant positive effects on BV infection. Conclusions Sexual behavioural factors and the presence of STIs were significantly associated with BV. The SEM analysis showed the interaction of contraceptive use and sexual behavioural factors. No interaction between the STIs and sexual behaviour could be demonstrated in this study.

There is considerable evidence to show that obesity is associated with the development of heart failure independent of traditional risk factors. However, clarity is required on the process involved in the transition from obesity-associated left ventricular hypertrophy (LVH) to LV dysfunction. In the present thesis I evaluated the extent to which central obesity explains variations in LV diastolic function at a community level independent of LV mass (LVM), LV remodelling or haemodynamic factors; whether obesity-related increases in LVM exceeding that predicted by workload (inappropriate LVM [LVMinappr] or alternative haemodynamic factors explains variations in LV ejection fraction (EF) at a community level; whether regression of LVMinappr is more closely associated with improvements in EF than LVM or LVM index (LVMI); and whether obesity-associated insulin resistance may explain decreases in LV diastolic function and variations in LVMinappr. Data were obtained in either 626 or 478 participants whom were representative of a randomly selected community sample and in 168 mild to moderate hypertensives treated for 4 months. In 626 randomly selected participants over 16 years of age from a community sample with a high prevalence of excess adiposity (~24% overweight and ~43% obese) after adjustments for a number of confounders including age, sex, pulse rate, conventional diastolic (or systolic) blood pressure (BP), antihypertensive treatment, LVMI and the presence of diabetes mellitus or an HbA1c>6.1%; waist circumference (p=0.0012) was independently and inversely associated with a reduced early-ro-late transmitral velocity (E/A), with similar findings noted for e’/a’ in a subset of 212 participants with tissue Doppler measurements. Waist circumference-E/A relationships persisted even after adjustments for other adiposity indices including body mass index (BMI) (p<0.05-0.005). No independent relationships between adiposity indices and E/e’ were noted (n=212). In contrast to the effects on diastolic function, waist circumference was not correlated with EF (p=0.83). The independent relationship between waist circumference and E/A was second only to age and similar to BP in the magnitude of the independent effect on E/A. The inclusion of relative wall thickness rather than LVMI in the regression equation produced similar outcomes. The inclusion of carotid-femoral pulse wave velocity (PWV), or 24-hour BP as confounders, failed to modify the relationship between waist circumference and E/A. Thus, waist circumference is second only to age in the impact of the independent association with E/A in a community sample with a high prevalence of excess adiposity. This effect was not accounted for by left ventricular hypertrophy or remodelling, 24-hour BP or arterial stiffness. In 478 randomly selected participants from a community sample, waist circumference, but not BMI was independently associated with the homeostasis model assessment of insulin resistance (HOMA-IR). HOMA-IR was inversely correlated with E/A (p<0.0001) and in a multivariate model with adjustments for waist circumference, age, sex, conventional diastolic or systolic BP, diabetes mellitus or an HbA1c>6.1%, regular tobacco use, regular alcohol intake, pulse rate, treatment for hypertension and either LVMI or LV relative wall thickness in the model, the relationship betwreen HOMA-IR and E/A persisted (partial r=-0.13 to 0.14, p<0.005). With further adjustments for either 24-hour systolic or diastolic BP (partial r=-0.11, p<0.05, n=351) or for aortic PWV (partial r=-0.11, p<0.02, n=410), the independent relationship between HOMA-IR and E/A also remained. Therefore, the relationship between indices of an excess adiposity and abnormalities in LV diastolic function may be explained in-part by insulin resistance beyond haemodynamic factors. In 626 randomly selected adult participants from a community sample with a high prevalence of obesity, the strongest independent predictor of LVMinappr was BMI (p<0.0001). With adjustments for LV stress and other confounders there was a strong inverse relationship between LVMinappr and EF (partial r=-0.41, p<0.0001), whilst only modest inverse relations between LVM or LVMI and EF were noted (partial r=-0.07 to -0.09, p<0.05-0.09)(p<0.0001, comparison of partial r values). The independent relationship between LVMinappr and EF persisted with further adjustments for LVM or LVMI (partial r=-0.52, p<0.0001). LVMinappr and LV midwall fractional shortening were similarly inversely related (p<0.0001) and these relations were also stronger than and independent of LVM or LVMI. In conclusion, in a community sample with a high prevalence of obesity, inappropriate LVM is strongly and inversely related to variations in EF independent of and more closely than LVM or LVMI and BMI was the strongest independent determinant of inappropriate LVH. Therefore LVH is a compensatory response to workload, but when exceeding that predicted by workload, as may occur in obesity, is associated with LV systolic chamber decompensation. In 168 mild-to-moderate hypertensives treated for 4 months, although in patients with an LVMI>51g/m2.7 (n=112)(change in LVMI=-13.7±14.0 g/m2.7, p<0.0001), but not in patients with an LVMI≤51g/m2.7(n=56)(change in LVMI=1.3±9.3 g/m2.7) LVMI decreased with treatment; treatment failed to increase EF in either group (1.2±10.8% and 2.7±10.7% respectively). In contrast, in patients with inappropriate LVH (LVMinappr>150%, n=33) LVMinappr decreased (-32±27%, p<0.0001) and EF increased (5.0±10.3%, p<0.0001) after treatment, whilst in patients with a LVMinappr≤150% (n=135), neither LVMinappr (-0.5±23%), nor EF (0.9±10.3%) changed with therapy. With adjustments for circumferential LV wall stress and other confounders, whilst on-treatment decreases in LVM or LVMI were weakly related to an attenuated EF (partial r=0.17, p<0.05), on-treatment decreases in LVMinappr were strongly related to increases in EF even after further adjustments for LVM or LVMI (partial r=-0.63, confidence interval=-0.71 to -0.52, p<0.0001). In conclusion, decreases in LVMinappr are strongly related to on-treatment increases in EF beyond changes in LVM and LVMI. LVH can therefore be viewed as a compensatory change that preserves EF, but when in excess of that predicted by stroke work, as a pathophysiological process accounting for a reduced EF. In 478 participants of a randomly selected community sample with adjustments for waist circumference, age, sex, conventional systolic BP, diabetes mellitus or an HbA1c>6.1%, regular tobacco use, regular alcohol intake, pulse rate, and treatment for hypertension, an independent relationship between HOMA-IR and LVMinappr was noted (partial r=0.14, p<0.002). With further adjustments for either 24-hour systolic BP (partial r=0.11, p<0.05, n=351), aortic PWV (partial r=0.13, p<0.02, n=410), or circumferential LV wall stress (partial r=0.12, p<0.02, n=478) the independent relationship between HOMA-IR and LVMinappr also remained. Thus, the relationship between indices of an excess adiposity and LVM beyond haemodynamic factors may be explained in-part by insulin resistance. In conclusion, the results of the present thesis provide clarity on the process involved in the transition from obesity-associated LVH to LV dysfunction. In the present thesis I demonstrated that an index of central obesity explains a considerable proportion of the variation in LV diastolic function at a community level independent of LVM, LV remodelling and haemodynamic factors; that obesity-related increases in LVM exceeding that predicted by workload (LVMinappr) or alternative haemodynamic factors explains a marked proportion of variations in EF at a community level; that regression of LVMinappr is more closely associated with improvements in EF than LVM or LVM index (LVMI); and that obesity-associated insulin resistance may explain decreases in LV diastolic function and variations in LVMinappr and hence EF. Therefore, studies are warranted to evaluate the impact of interventions that improve insulin sensitivity on obesity-related decreases in LV diastolic function and increases in LVMinappr.

D.Med.. Faculty of Medicine, University of the Witwatersrand, 1973

Sexually transmitted infections (STI’s) are a major public health problem. If STI’s are not treated they can cause infertility, long term disability and death. Partner notification and partner treatment have been identified as important aspects of management to curb the chain of transmission, reinfection and complications of STI’s. The high prevalence of STI’s and low partner treatment rate is cause for concern. The ability to communicate with sexual partners about going to the clinic for treatment is the cornerstone in breaking the chain of reinfection and preventing complications. The aim of the study was: • To determine the percentage of patients presenting as a result of partner notification. • To describe the demography of patients attending the STI clinic. • To determine the preferred methods of partner notification from the perspective of being a patient and from the perspective of being a sexual contact/partner. The study is a replication of the study entitled ‘Patient Preferences for Partner Notification of Sexually Transmitted Infections by (Apoola, Radcliffe, Das, et al.,2006:327). ’ The study is a quantitative, descriptive, survey design, and a replicated self-administered questionnaire of the study was used. The sample of 162 patients was taken from a population of about 800 STI clinic attendees over a period of one month at a local public sector clinic in Johannesburg. Data was captured using an excel spread sheet and then were exported to the Stata Release 11 program for analysis. Data was summarized using frequencies, means, and percentages. Reliability, validity and ethical issues were taken into consideration. From the results of the study it became apparent that the majority of STI patients 156(96%) attending the STI clinic under study preferred to inform their partners themselves that the partner may be at risk of an STI and should receive treatment. Furthermore, the participants in this particular study would also prefer to be informed by their partner if they were potentially at risk of contracting a sexually transmitted infection. With respect to the demographics of the clinic attendees, the majority of the patients attended the clinic because they presented with signs and symptoms of what they believed to be a sexually transmitted infection (92%), and only 8% of the participants attended the clinic because they were informed by a partner that they have been potentially exposed to an STI. It was identified that 92% of participants did have cellular telephones, and this is potentially a good means of partner notification given that the majority of the research sample had access to cellular telephones. In conclusion the participants in this particular study would prefer to notify their partner themselves of the potential exposure to a STI as opposed to other means of partner notification.

A dissertation submitted to the Faculty of Health Sciences, University of the Witwatersrand, Johannesburg in partial fuifillment of the requirements for the degree of Master of Medicine in Ophthalmology, / This dissertation describes the causation and management of bacterial keratitis at St John Eye Hospital. [Abbreviated Abstract. Open document to view full version] / AC2017

Title: Risk factors for sexually transmitted infections among mine workers in Orkney, North West Province, South Africa. Background: The role of mobile populations in the spread of HIV has been documented in several countries of the world. In South Africa, the relationship between mine migration and HIV has been studied in detail in the mining town of Carletonville and in Welkom. The link between HIV acquisition and transmission has been well documented. Prevention and early treatment of sexually transmitted infections have been identified as public health priorities as reflected in HIV/AIDS, TB and STI strategic plan of South Africa (2012 – 2016). In this study we sought to measure the prevalence of STIs among mine workers at baseline before a planned STI treatment intervention. Objectives: To: 1) Measure the prevalence of STIs amongst the mine workers. 2) Describe the types of STI in the population. 3) Identify risk factors associated with genital ulcers diseases. Results: The highest percentage of STI positivity 188 (10.6%) was observed in the youngest male group (<30) in the study population and decreasing by age (50-64) at 1.8%. We found that of the 1685 participants, 78 (4.6%) had any STI, with 46 (2.9%) having chlamydia, 20 (1.3%) having gonorrhea and 7 (0.4%) having genital ulcer STI. Age was found to be a significant predictor of Chlamydia status. Fitting a multiple logistic regression model showed that the age group of a participant and whom the participant lived with were the two major independent factors that were associated with the risk of a person having an STI. Conclusion: There is a high demand for STI prevention programmes to focus on the younger age group. A surprising finding that in fact risk of STIs was higher among men living with their partners than among those in the single-sex hostels, where we expected to find the highest risk. Targeted door to door prevention education campaigns may go a long way in modifying the behaviour of having multiple sexual partners.

Dissertation submitted to the Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, in fulfillment of the requirements for the degree of the Master of Science in Medicine, Johannesburg, 2013 / Cardiac disease is a major cause of morbidity and mortality in patients with chronic kidney disease (CKD). Accurate evaluation of cardiac function is therefore important but difficult with commonly used imaging modalities such as echocardiography being subject to variable load changes in haemodialysis.

University of Macau / Faculty of Health Sciences