Theses and Dissertations from UMD
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New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a give thesis/dissertation in DRUM
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Item EVALUATING THE EFFECTS OF MODIFIABLE LIFESTYLE AND CARDIOVASCULAR HEALTH FACTORS ON DIABETES LIFE EXPECTANCY IN NHANES AND BRAIN AGING IN UK BIOBANK(2024) Feng, Li; Lei, David K.Y. DL; Ma, Tianzhou TM; Nutrition; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This dissertation explored the impact of lifestyle and cardiovascular health factors on aging, particularly focusing on individuals with diabetes, the effects of blood pressure on brain aging, and the influence of cardiovascular health and genetic predispositions on brain white matter aging.The first study examined the trends in lifestyle quality among US adults with type 2 diabetes from 1999 to 2018 using NHANES data, involving 7,410 participants. A healthy lifestyle score encompassing smoking, drinking, physical activity, and diet showed a slight increased over the years. Notably, disparities remained significant by socioeconomic groups. The study found that adherence to low-risk lifestyle factors was associated with a 55%-57% lower risk of all-cause mortality, emphasizing the importance of lifestyle modification in diabetes management, and it was independent of cardiovascular risk control. The second study investigated the causal effect of elevated blood pressure on white matter brain aging in a cohort of 228,473 European ancestries aged 40-69 from the UK Biobank by using two-sample Mendelian randomization. Our result revealed that high blood pressure, particularly diastolic, accelerated the machine-learning-derived white matter brain age gap, based on white matter microstructure integrity measured by fractional anisotropy derived from diffusion tensor imaging data, with a causal effect evidence found in late middle-aged women. This underscores the importance of blood pressure control in preventing brain aging, especially in post-menopausal women. Lastly, the impact of Life's Essential 8 (LE8), a comprehensive measure of cardiovascular health (lifestyle part: diet, smoke, physical activity, sleep; health part: BMI, blood sugar, blood pressure, blood lipid), on white matter brain aging was assessed, with a particular focus on how the APOE4 genotype modifies the relationship. Analyzing data from 18,817 European ancestries aged 40-60 from the UK Biobank, the study revealed that higher LE8 scores correlated with a younger brain age. Interestingly, the effect varied significantly with APOE4 status, highlighting the need for personalized health strategies based on genetic profiles. In conclusion, these studies collectively highlight the crucial role of modifiable lifestyle and health factors in managing chronic diseases, controlling blood pressure, and maintaining brain health, with an emphasis on the integration of genetic profiles for personalized healthcare.Item NOVEL STATISTICAL METHODS IN HEALTHCARE ANALYTICS FOR PEOPLE WITH DIABETES AND PREDIABETES(2021) Liu, Shiping; Smith, Paul; Gao, Guodong; Mathematical Statistics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)A great amount of statistical tools and methods have been applied in health care analytics to assist decision making and improve the quality of diabetes related health care services.However, limitations of existing methods, new types of data, and specific demands in different areas are challenging current statistical tools. These challenges further encourage developing new statistical methods or extending existing methods to better fit different demands and improve performance of models and methods in practice. In this dissertation, we developed, applied, and extended many innovative statistical models and methods to address practical issues in health care of diabetes related population. Firstly, we developed a novel automated event detection method for univariate time series, Continuous Glucose Monitoring (CGM) data, from diabetic patients. Secondly, we invented a low-dimensional framework to classify and track longitudinal glucose status of CGM users based on within-subject analysis and unsupervised variable selection methods. Thirdly, we investigated the influence of daily activities on glucose series by applying a nonparamentric multivariate two sample test with independence assumption relaxed. Moreover, besides focusing on diabetic population, we also developed predictive models to access the risk of diabetes for population with prediabetes in later two chapters. Two types of response variables, binary indicator and HbA1c values, were used to aid different demands in practical healthcare services.Item SURVIVING THE STORM: AN INTERSECTIONAL ANALYSIS OF HURRICANE KATRINA’S EFFECT ON LINGERING PHYSICAL AND MENTAL HEALTH DISPARITIES(2020) DeLoatch, Nicole T.; Rendall, Michael S; Sociology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This three-paper dissertation used an intersectional analytical framework to examine disparities in physical health and mental health (respectively) for Hurricane Katrina survivors by race and gender. To do so, health outcomes for New Orleans residents who survived Hurricane Katrina were analyzed. Displaced New Orleans Resident Survey (DNORS) data was used to investigate if natural disasters exacerbate health disparities. In Chapter 2, eight waves of self-reported data from the nationally-representative Panel Study of Income Dynamics (PSID) were used to conduct a sensitivity analysis of self-reported diagnoses. This was done to determine if there are differences by race and sex in the accuracy of self-reports. Chapter 2's analysis indicates that the intersections of race and sex were not associated with reporting variability after accounting for proxy status and class related characteristics. In Chapters 3 and 4, we determine if significant increases to physical and mental health diagnosis vary by race and sex, following Hurricane Katrina. The main finding of Chapter 3 was that Black women were more likely to report negative physical health outcomes than their White or male counterparts, both before and after Hurricane Katrina. Chapter 4's main finding was that Black women were not more likely to report a diagnosis of negative emotional problem and depression post-Katrina when compared to their White or male counterparts. There were increased adverse mental health outcomes across all four race-sex groups.Item Diabetes and Periodontal Disease Bi-Directional Relationship: An Examination of Diabetics' Knowledge, Understanding, Social Determinants and Self-Efficacy Impact on Dental Hygiene Practices(2019) Oguntimein, Oluwamurewa Ayodeji; Butler, James; Horowitz, Alice M; Public and Community Health; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Thirty million Americans are living with diabetes; making it the seventh leading cause of death, with 1.3 million Americans dying every year. As such, the total treatment costs of diabetes rose from $245 billion in 2012 to $327 billion in 2017. One factor driving these high costs is diabetes’ comorbidity with other chronic diseases and associated complications – e.g., hypertension, , heart disease, stroke, amputation and blindness. Little attention has focused on periodontal disease- the sixth complication of diabetes awareness, education, and intervention. This research adds to the literature via two studies that assessed diabetics’ knowledge and understanding of the bi-directional relationship between diabetes and periodontal disease. The first study examined gender and self-efficacy differences in knowledge and understanding of the bi-directional relationship between diabetes and periodontal disease among 927 diabetics. Findings suggest diabetics are unaware of their increased risk of periodontal disease based on the low mean 5.79±2.366 scores on the knowledge and understanding scale. After controlling for diabetes duration, smoking status, and other covariates, males had less knowledge and understanding of the bi-directional relationship (p<.0001). Self-efficacy was not significantly associated with participants’ knowledge and understanding of the bi-directional relationship (p= 0.543). The second study assessed health literacy differences in diabetics’ knowledge and understanding of the bidirectional relationship between diabetes and periodontal disease. Education, employment and income were tested as moderators between knowledge and understanding of the bidirectional relationship and dental hygiene practices. After controlling for diabetes duration, dental insurance status, and other covariates, participants with marginal or inadequate health literacy had less knowledge and understanding of the bi-directional relationship compared to participants with adequate health literacy (p<.0001). Education, employment, and income were not moderators. The findings support the need for targeted periodontal disease risk and dental hygiene practice education. These studies are presumably the first to assess diabetics’ knowledge and understanding of the bi-directional relationship between diabetes and periodontal disease. These studies are significant contributions to the limited amount of research and illuminate the need to educate diabetics regarding their increased risk of periodontal disease and the importance of practicing dental hygiene behaviors to prevent diabetes complications.Item MODULATING KEY GENES INVOLVED IN PANCREAS FORMATION AND INSULIN SIGNALING USING CRISPR/CAS9 IN THE PIG(2019) Sheets, Timothy P; Telugu, Bhanu P; Animal Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Among the metabolic diseases, diabetes remains a “pressing problem” as recognized by World Health Organization, not only due to the impact on individuals’ lives, but also because of the rapid increase in newly diagnosed patients. To better understand the mechanisms of diabetes, this dissertation investigates the role of NGN3 in pancreas development using CRISPR/Cas9 gene targeting in the pig model. NGN3 was selected for study because of its critical role in endocrine pancreas formation. Our research demonstrates that the targeted ablation of NGN3 blocks development of the endocrine pancreas, a finding supported through gene expression analysis. Furthermore, follow-up studies show that clonal piglets derived from NGN3-ablated animals lack the major endocrine islet cell types and subsequent expression of key endocrine hormones. This porcine model provides valuable insights into the study of type 1 diabetes in early post-natal life and future applications of human-to-pig chimeric organ development for transplant surgery. Expanding upon this porcine model for diabetes, we sought to apply this approach to the study of type 2 diabetes using a novel pig model, thus bridging the gap between mouse and human. For this endeavor, we identified GRB10 as a potential critical mediator in insulin signaling, development, and growth potential following an extensive literature review. The potential for dual applications in both agriculture and medicine was also identified as an objective. Analysis of qPCR data from in vitro overexpression studies supports that GRB10 modulates insulin signaling through the canonical insulin pathway. Additional data from two in vivo gene editing trials targeting the GRB10 locus in both Ossabaw and domestic pig breeds show a supportive qualitative trend towards growth regulation in the Ossabaw pig breed. Further evidence is required to determine whether GRB10 plays the same role in the domestic pig, as a limited cohort size of mutants precluded an extensive analysis of phenotypes. Together, our assessment of NGN3 and GRB10 offer significant potential for modeling of both type 1 and type 2 diabetes as well as modeling of growth traits in the pig through application of advanced genome engineering technology.Item Exposure to Ambient Air Pollution and Correlates of Cardiovascular Disease among Youth with Type 1 Diabetes(2019) Montresor-Lopez, Jessica Anne; Puett, Robin C; Maryland Institute for Applied Environmental Health; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Air pollution from traffic-related sources is associated with cardiovascular disease (CVD), potentially through changes in systemic inflammatory responses, vascular function and oxidative stress leading to atherosclerosis, thrombosis or endothelial dysfunction. Individuals with type 1 diabetes (T1D) have a greater risk of CVD-related morbidity and mortality than the general population, and they may be more susceptible to the effects of air pollution on CVD. Although these increased risks begin during childhood, very few studies have assessed the impact of air pollution on children and youth with T1D. This dissertation directly addresses gaps in the epidemiologic evidence by: 1) evaluating the relationship of short-term exposures to traffic-related air pollutants with pulse wave velocity (PWV), a measure of arterial stiffness, 2) assessing the effects of changes in air pollution exposures on changes in inflammatory biomarkers, including C-reactive protein, fibrinogen and interleukin-6 (IL-6), and 3) examining the relationship of long-term exposures to traffic-related air pollution with allostatic load (AL), a measure of cumulative biological risk, among a cohort of youth with T1D. Data were obtained from the SEARCH for Diabetes in Youth (SEARCH) study. SEARCH was initiated in 2000 and includes a diverse population of US youth diagnosed with diabetes prior to age 20 years. Anthropometric and laboratory measures were taken at SEARCH study visits, and standardized questionnaires were used to collect information on important covariates. Air pollution exposures were estimated using spatio-temporal models and assigned to residential addresses for each participant. In the first study, we identified a significant association between increased exposure to PM2.5 on the day of the examination with higher PWV using generalized linear models adjusted for lifestyle and demographic characteristics. In the second analysis, we found consistent positive effects of increases in PM2.5 over the week prior to the examination with IL-6 using longitudinal mixed models. In the third study, no significant associations were observed for monthly and annual PM2.5 exposures or proximity to major roadways with AL in fully adjusted linear mixed models. However, effects differed by race/ethnicity and gender. Overall, this research indicates that youth with T1D may be at higher risk for air pollution-related cardiovascular impacts.Item Form And Function Glucometer Evaluation For Specialized Populations(2014) Santos, Luis Samai; Vaughn-Cooke, Monifa; Mechanical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Patient self-management technologies (glucometer, blood pressure monitor, etc.) are a critical component of chronic disease care. Although these technologies are intended to support patient activities, low device usability can produce design imped-iments that may negatively impact patient adherence and hence treatment outcomes. In particular, patients with disabilities, who are the majority of the chronic disease population, are typically excluded from medical device usability studies required for FDA approval. This study aims to develop a usability method to: 1) evaluate patient self-management technology and 2) inform design decision making for disabled pa-tients. The study will focus on handheld device use (glucometers) for diabetic patients with mobility and vision impairment. An initial expert usability analysis was per-formed for 13 glucometers to determine the design features that are most problematic for disabled users. The usability analysis informed the design of an experiment to test disabled user performance and satisfaction for several meter interaction tasks. Com-mon diabetes disabilities were simulated in healthy subjects through the use of glasses (retinopathy, glaucoma) and gloves (arthritis, neuropathy) to evaluate the experimental protocol prior to future testing in the actual disease population. Results suggested a preference of participants for large text, large protruding buttons, and contrast color between case and buttons to facilitate locating buttons. Future studies will integrate the disabled diabetic population in the data collection and integration of these results in the design of a new glucometer. This work can inform regulatory guidelines for usability testing with disabled patients and the patient-centric design practices of medical device manufacturers.Item Observations regarding consumption of Peruvian native grains (quinoa, amaranth and kañiwa), weight status, and perceptions of potential risk factors, warning signs and symptoms of type 2 diabetes among Peruvian adults: A case study(2012) Sanchez, Katherine A.; Kantor, Mark A; Nutrition; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Wheat flour-based foods and rice have replaced native cereals in the diets of many urban-living Peruvians. Urban areas have also seen increases in overweight, obesity, and type 2 diabetes mellitus prevalence in recent years. The focus of this research is to describe observations regarding consumption of quinoa, amaranth and kañiwa cereals; weight status; and self-described experiences of potential risk factors and warning signs for, and symptoms that may represent complications of, type 2 diabetes mellitus in Peruvian adults living in the city of Arequipa. A survey instrument was developed and administered to 110 subjects (22 diabetics, 88 non-diabetics), middle-aged and over. Participants with normal BMIs consumed quinoa, amaranth, and kaniwa more frequently than overweight or obese participants. Diabetics reported more frequent consumption of Andean cereals, particularly amaranth, and less frequent consumption of white flour than non-diabetics. Most participants reported eating a diet high in carbohydrates and leading a sedentary lifestyle.Item COMPARISONS OF WAIST CIRCUMFERENCE, WAIST-TO-HIP RATIO AND BODY MASS INDEX AND THEIR ASSOCIATIONS WITH TYPE 2 DIABETES IN RURAL AND URBAN INDIA(2011) Shirey, Katherine Abigail; Sahyoun, Nadine; Nutrition; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)India has the highest prevalence of diabetes mellitus in the world. Anthropometric measurements (waist circumference (WC), waist-to-hip ratio (WHR) and body mass index (BMI)) are risk factors of Type 2 diabetes mellitus (T2DM). This study examined associations between these anthropometric measures and T2DM among 508 urban Indians in New Delhi and 574 rural Indians in Tamil Nadu. Using a receiver operator curve (ROC) the anthropometric cutpoints most strongly associated with T2DM were determined. Bivariate correlation and the area under the ROC curve showed most significant associations between T2DM and WHR (0.90 cm, 0.86; 0.87, 0.81 urban and rural men and women, respectively) followed by WC (86 cm, 85; 86, 75) and then BMI (24 kg/m2, 21; 25, 22). Results from this study showed large variations in cutpoints between the rural and urban populations and suggest that no single cutpoint should be used in India due to large intra- and inter- regional differences within the country.