published_or_final_version / Community Medicine / Master / Master of Philosophy

published_or_final_version / Community Medicine / Master / Master of Public Health

Thesis (MSc (Biomedical Technology))--Cape Peninsula University of Technology, 2016. / Cardiovascular diseases (CVD) are the leading cause of global mortality, of which over 75% occurred in low- and middle-income countries such as South Africa. The lipid profile, specifically decreased levels of high density lipoprotein cholesterol (HDL-C), elevated triglyceride levels and the presence of small-dense low density lipoprotein (sdLDL) has been reported associated with CVD. An increased number of sdLDL is also common in metabolic syndrome (MetS), visceral obesity and diabetes mellitus, the last a known risk factor for CVD. The modification of low density lipoprotein (LDL) size, or number of sdLDL particles, has been reported to significantly reduce CVD risk, but not conclusively so and needs further investigation. In this regard, sdLDL particles are seldom estimated routinely for clinical use because of financial and other limitations. Currently, an alternative approach for estimating sdLDL is to use equations derived from routine lipid measures, as has been proposed by several groups. However, there is a need for extensive evaluation of this equation across different ethnic and disease groups, especially since reports showed an inadequate performance of the equation in a Korean population. The aim of this study was to assess the performance of a recently proposed equation for the estimation of sdLDL in healthy and diabetic mixed ancestry South Africans. Furthermore, we also investigated the role of sdLDL as a cardiometabolic risk factor, as measured against known risk factors such as the glycemic and lipid profiles.

Helicobacter pylori (H. pylori) is a microaerophilic, Gram-negative motile curved rod that inhabits the gastric mucosa of the human stomach. The organism chronically infects billions of people worldwide and is one of the most genetically diverse of bacterial species. Infection with the organism potentially induces chronic gastritis and peptic ulcer disease. In addition, H. pylori plays a role in the etiology of gastric cancer and gastric MALT lymphoma. The risk of infection is increased in those living in the developing world, which has been ascribed to precarious hygiene standards, crowded households, and deficient sanitation common in this part of the world. Thus, the aim of this study was to identify the risk factors in the transmission of H. pylori in our environment, i.e. in Nkonkobe Municipality in the Eastern Cape Province, South Africa. Faecal samples were collected from 356 apparently healthy subjects, consisting of 168 males and 188 females aged from 3 months to 60 years (Mean = 31 years). A standardized questionnaire was applied, it described demographic characteristics including age, sex, household hygiene, socioeconomic status, area of residence, duration of stay in the area, sharing bath water, sharing tooth brush, habit of sucking thumb, medication currently being taken or medication taken within the past three months, source of water, type of toilet used, education and occupation. A sandwich-type enzyme immunoassay amplification technology (Amplified IDEIA TM Hp StAR TM , Oxoid, UK) was used to analyze the faecal samples for the detection of H. pylori antigens using monoclonal antibodies specific for H. pylori antigens. To assess the possibility of faecal oral route with tap water as an intermediary link, PCR targeting the ureC (glmM), a highly conserved gene in H. pylori ii was carried out to detect H. pylori DNA in faecal samples of already positive samples by HpSA test as well as in direct tap water used by the H. pylori positive subjects. QIAamp DNA stool mini kit was used to extract DNA from faecal samples. Tap water samples were then obtained using sterile bottles from areas inhabited by H. pylori positive subjects as determined by HpSA test and PCR. DNA extraction from water samples was done using UltraCleanTM Water DNA Isolation Kit (0.22μm) according to the manufacturer’s instructions. PCR with primers specific for H. pylori glmM gene was carried out with both positive and negative controls incorporated. Fisher’s exact test was used to assess the univariate association between H. pylori infection and the possible risk factors. Odds ratio (OR) and the corresponding 95 percent confidence interval (CI) were calculated to measure the strength of association using EPI INFO 3.41 package. P values of < .05 were required for significance. The precision rate of the diagnostic tests used was also determined. H. pylori antigen was detected in 316 of the 356 subjects giving an overall prevalence of 88.8 percent. Prevalence increased with age from 75.9 percent in children < 12 years age to 100 percent in the age group from 13 years to 24 years, also 100 percent prevalence of H. pylori was recorded in young adults aged 25-47 years and subjects aged 60 years (P < .05). H. pylori prevalence was higher in females than in males. Of 188 females who participated in the study, H. pylori antigen was detected in 172 (91.5 percent) versus 144 (85.7 percent) of 168 males (P > .05). Interestingly, H pylori antigen was detected more often (100 percent) in the high socioeconomic group than in those of low socioeconomic group (85.9 percent). Sixteen (66.7 percent) of twenty four faecal samples that had previously tested positive for the organism by HpSA test were confirmed positive by PCR. However none of the treated tap water samples tested positive for the organism by PCR. The present iii study revealed a high prevalence of H. pylori in faecal samples of asymptomatic individuals in the Nkonkobe Municipality, an indication of active infection. The obtained results also revealed that direct treated tap water might not be playing a crucial role in the oral transmission of H. pylori in the studied population.

As the leading cause of death in the United States, coronary heart disease (CHD) is a growing public health problem, despite the fact that many risk factors for the disease are preventable, especially if addressed early in life. The purpose of the current study was to examine the effects of loss-framed versus gain-framed versus information-only health messages on both intention to attend and actual attendance at an appointment to get screened for CHD risk factors (i.e., hypertension, diabetes, and dyslipidemia). It was hypothesized that a population of young adults would be more likely to view screening for CHD risk factors as a low-risk, health-affirming behavior as opposed to a risky, illness-detecting behavior and would thus be more strongly influenced by gain-framed messages than loss-framed messages. Additional goals included the exploration of the extensively researched individual health beliefs of perceived threat (as defined by the health belief model) and health locus of control as they relate to message frames. One hundred forty-three undergraduate students were randomly assigned to either the loss-framed, gain-framed, or information-only control conditions. Framing manipulation checks revealed that participants failed to discern differences in the tone and emphasis of the experimental pamphlets. As a result, no tests of framing effects could be conducted. Sixteen (11.2%) of the 143 participants who participated in Part 1 of the experiment participated in Part 2 (i.e., attended a risk factor screening appointment). Multiple regression analysis revealed risk index, age, and powerful others health locus of control as significant predictors of screening intention. Gender was the only demographic or health related variable that was significantly related to screening outcome, such that women were more likely to get screened than men. Limitations and recommendations are discussed.

The purpose of this dissertation was to understand how genetics, socioeconomic status (SES), and lifestyle factors influence the development of age-related macular degeneration (AMD), glaucoma, and diabetic retinopathy in an adult population in Dallas County. Two hundred fifty-three older adults participated in this study as the sample. Crosstabulation and binary logistic regression were utilized to analyze the data. Results indicated a disparity among participants' test scores, visual health status, and perceptions of their visual impairment and highlighted the fact that many seniors are not educated about age-related retinal disorders. Furthermore, variables reaching statistical significance were consistent with the literature included race/ethnicity, age, having a family history of both AMD and diabetes, frequency of eye exams, and level of education. The results not consistent with the literature as affecting visual health included health insurance, access to health care, body weight, and smoking status. Recommendations for future study included applied research focusing on determining risk factors, raising awareness, educating, and providing early detection of these diseases among low to middle income Caucasian, African American, and Hispanic older adults.

This study addressed the specific problem of whether there is a significant correlation between stress and the onset of predisposed disease. Because most graduate programs are stressful and it is known that several social work graduate students in one cohort at CSUSB were diagnosed with diabetes as well as migraines and depression, the population for this study was Master's of Social Work (MSW) students at California State University, San Bernardino, (CSUSB).

Magister Public Health - MPH / Background: Dental canes and gingivitis are reported to affect 60-90% of school children in most countries (World Health Organization, 2003). Learners in the Swakopmund district of Namibia were examined and it was found that 73% and 89% of them were affected by dental caries and gingivitis respectively (Ministry of Health and Social Services, 2003). This district has implemented an oral health programme at primary schools with the aim of reducing the prevalence of dental caries and gingivitis. Aim: To compare knowledge, attitudes and behaviour of teachers and learners in response to the school-based oral health programme at four primary schools in Swakopmund district. Study Design: This study is a cross-sectional survey that compared the responses of learners from high participating schools to those from low participating schools. The total sample was 186 participants comprising of 159 learners and 27 teachers. Data Collection: Structured, self-administered questionnaires were used for the teachers whilst learners were interviewed by the researcher and research assistants using structured questionnaires. Data on knowledge of risk factors for dental caries and gingivitis as well as attitude and behaviour towards prevention of these diseases at school were collected. Data analysis: Data were captured in Microsoft Excel Programme and imported to CDC Epi Info 2002 version 3.3 for analysis. Prevalence ratio (PR) was used as a preferable measure of effect at 95% confidence interval. Chi-square test was used to assess statistical significance of the proportional differences between high and low participating schools and the cut off point for statistical significance was a p-value < 0.05. 111 Results: Learners from low participating schools were more knowledgeable than learners from high participating schools in most of the knowledge questions and the results were statistically significant. There were positive oral health practices and attitudes reported by the learners with minimal differences between high participating and low participating schools and consequently the results were not statistically significant. The results for the variables knowledge, behaviour and attitudes for the teachers were not statistically significant. Teachers from both high and low participating schools exhibited high levels of knowledge and positive oral health behaviours and attitudes. However, teachers reported some shortcomings in the programme which included lack of: toothbrushes, parental involvement, time for oral health activities, regular workshops and educational materials. Conclusion: The study revealed that learners and teachers from both high and low participating schools had positive oral health knowledge, attitudes and behaviour towards oral health. However, certain socio-environmental factors which are important determinants of oral health could explain the reasons for low participation in oral health programme by some schools. Therefore the Health Promoting Schools approach is a pragmatic way to promote oral health at schools in Swakopmund district because a Health Promoting School has a healthy public policy that creates a supportive environment for oral health, making healthy choices easier.

Cardiovascular disease (e.g., myocardial infarction, stroke, coronary artery disease) is the leading cause of death and disability worldwide. There is a growing body of literature that indicates sexual minority (e.g., gay, lesbian, bisexual, queer) adults are at a higher risk of cardiovascular disease than their heterosexual counterparts. The aim of this dissertation was to identify factors that contribute to the cardiovascular health (CVH) disparities that have been observed among sexual minority individuals. Guided by an adaptation of the minority stress model of CVH among sexual minority individuals, this dissertation includes three studies. In the first study (i.e., Chapter 2), we conducted a scoping review of the literature that investigated social determinants of cardiovascular health among sexual minority adults. Although findings were mixed, several social determinants of health were found to influence the CVH of sexual minority adults. For instance, sexual minority adults who lived in environments that were more supportive of sexual and gender minority people had lower odds of being overweight or obese. In the second study (i.e., Chapter 3), we used data from a racially and ethnically diverse sample of sexual minority women to examine the associations of family-related factors (i.e., sexual identity disclosure and family social support) with self-reported incident hypertension. Additionally, we examined whether these associations were moderated by race/ethnicity and sexual identity, or mediated by depressive symptoms. We found that higher levels of family social support were associated with lower levels of depressive symptoms among sexual minority women. However, family-related factors were not associated with self-reported incident hypertension. Further, race/ethnicity and sexual identity did not moderate the associations between family-related factors and reported incident hypertension. In the third study (i.e., Chapter 4), we used data from a nationally representative sample of adults to investigate sexual identity differences in ideal CVH (as defined by the American Heart Association’s Life Simple 7) and whether these associations were mediated by depressive symptoms. Compared to exclusively heterosexual women, mostly heterosexual and lesbian women were less likely to meet ideal criteria for tobacco use. In contrast, lesbian women were more likely to meet ideal criteria for glycosylated hemoglobin than exclusively heterosexual women. Among men, relative to exclusively heterosexual men, mostly heterosexual men were less likely to meet ideal criteria for tobacco use. Gay and bisexual men were less likely to meet ideal criteria for physical activity, whereas gay men were more likely to meet ideal criteria for body mass index compared to exclusively heterosexual men. Bisexual men were less likely to meet ideal criteria for blood pressure relative to exclusively heterosexual men. Depressive symptoms were found to partially mediate the association between sexual identity and physical activity only among mostly heterosexual women. Overall, these dissertation findings highlight CVH disparities among sexual minority adults. Clinicians should be educated about the CVH disparities that have been documented among sexual minority adults to provide personalized and culturally competent care. Results also indicate there is a need to develop behavioral interventions tailored specifically to the needs of sexual minority adults to improve their CVH outcomes and reduce CVH-related disparities.

It is well established that continual consumption of a diet high in fat leads to the development of chronic conditions such as obesity, cardio metabolic syndrome, and atherosclerosis that are associated with high incidence of cardiovascular disease. Recent studies have identified endotoxin-derived inflammation as a major diving force for the development of these conditions. Our laboratory has recently demonstrated that consumption of a single high-fat meal results in acute postprandial endotoxemia and alters monocyte cell surface adhesion molecule expression and scavenger receptor CD36 expression. These collective projects describe our efforts to understand the physiological significance of these postprandial changes and if supplementation with spore-based probiotics are able to provide any form of protection against these responses that are associated with the onset of atherogenesis.