Theses and Dissertations from UMD
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Item Examining the Food-Insecurity Obesity Paradox among Latino Immigrants(2019) Amador, Maria Aileen; Garza, Mary A; King-Marshall, Evelyn C; Public and Community Health; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Obesity is linked to chronic illnesses such as type 2 diabetes, cardiovascular disease, and some cancers (breast, kidney, and liver). Food insecurity refers to lack of access to nutritious and safe food. Latinos are a rapidly growing population in the US with higher levels of food insecurity than the national average, and higher obesity rates than non-Latino white adults. The “food insecurity-obesity” is a paradoxical relationship seen in rising obesity and correspondingly high food insecurity rates. We examined demographic factors, acculturation, stress, dietary habits, and food access among Latina immigrants to understand this paradox. This sub-analysis (n=128) found that education level (p=0.03) and marital status (p=0.08) were significantly and marginally significantly associated with food security level. Additionally, this analysis helped to better describe a population that lacks research. A better understanding of the “food insecurity-obesity” paradox and related factors will inform future culturally-tailored interventions to address obesity among Latina immigrants.Item OBESITY, METABOLIC SYNDROME, AND CARDIOVASCULAR OUTCOMES IN PEDIATRIC KIDNEY TRANSPLANT RECIPIENTS(2017) Sgambat, Kristen; Lei, David; Nutrition; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Cardiovascular (CV) disease is a leading cause of morbidity amongst children after kidney transplant. The contribution of abdominal obesity and metabolic syndrome (MS) to CV risk is not well defined in this population. A prospective controlled longitudinal cohort study was conducted to investigate contributions of obesity and MS to CV morbidity in a multiracial pediatric kidney transplant population. Aims of the study were to 1) identify prevalence of CV and metabolic abnormalities 2) evaluate effects of obesity and MS on adverse CV outcomes, defined by left ventricular hypertrophy (LVH), impaired myocardial strain and increased carotid intima-media thickness (CIMT) and 3) identify the anthropometric measure of obesity, Body Mass Index (BMI), Waist-to-Height ratio (WHr), or Waist Circumference (WC), that best predicts CV risk. Transplant recipients had standard echocardiographic measures of left ventricular size and function, strain by speckle tracking echocardiography, and CIMT measured at 1, 18, and 30 months post-transplant. 35 pre-transplant echocardiograms were analyzed retrospectively. Multivariate longitudinal regression was used to determine associations of obesity and MS with CV outcomes. Results indicated obesity and MS are prevalent among pediatric kidney transplant recipients. WHr is a more sensitive indicator of obesity-associated adverse CV outcomes compared with BMI or WC, due in part to the prevalence of short stature in this population. Obesity, MS, and hypertension are associated with post-transplant LVH. Significant predictors of impaired longitudinal strain include obesity, hypertension, and a combination of MS with elevated LDL-C cholesterol, whereas higher estimated glomerular filtration rate confers a protective effect. African American pediatric kidney transplant recipients have increased CIMT, which is negatively impacted by MS, whereas the CIMT of non-African American children appears unaffected after transplant. In conclusion, obesity and MS adversely affect CV outcomes in pediatric kidney transplant recipients, highlighting the importance of efforts to maintain healthy weight, blood pressure, and lipid profile after transplant. Further studies are needed to investigate the etiology and consequences of increased CIMT in African American transplant recipients. Imaging techniques such as speckle tracking echocardiography and CIMT may provide a means of detecting subclinical myocardial dysfunction and provide opportunity for early intervention in this population.Item FOREIGN VERSUS U.S.-BORN BLACK ADULT OBESITY AND DEPRESSION: AN ANALYSIS OF ENDURING PATTERNS AND MECHANISMS(2017) Brewton-Tiayon, Shanna; Rendall, Michael; Milkie, Melissa; Sociology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Foreign-born Blacks have better health outcomes than U.S.-born Blacks. The extent to which the health status of foreign-born Blacks change with increased exposure to the U.S. socio-cultural environment is less known than for other immigrant groups. Two prominent theories used to understand foreign and U.S.-born health disparities are the immigrant health paradox theory and immigrant health assimilation theory. The literature is conclusive that foreign-born Blacks have better health outcomes than U.S.-born Blacks, but this dissertation questions the appropriateness of framing this pattern as an immigrant health paradox due to the better socioeconomic status (SES) of foreign-born Blacks, relative to U.S.-born Blacks in general. The literature has been inconclusive on the extent to which immigrant health assimilation describes the health trajectories of foreign-born Blacks with increased duration of residence of the first generation in the U.S. or in comparing the first generation to subsequent generations. This dissertation interrogates the utility of immigrant health assimilation theory to describe the health trajectories of Black immigrants. Specifically, the dissertation focuses on the health outcomes of body mass index (BMI), obesity, depressive symptoms and depressive disorder. The sample of the dissertation includes foreign and U.S.-born Blacks generally, first generation foreign-born Afro Caribbeans, second and third generation U.S.-born Afro Caribbeans and U.S.-born African Americans. Collectively the three papers of this dissertation confirm a healthy immigrant effect for the health outcomes studied, when comparing the foreign-born to U.S.-born Blacks generally or African Americans specifically. In these comparisons first generation foreign-born Blacks have better socioeconomic status than the U.S.-born or African Americans. There is an immigrant health paradox for the health outcomes studied when comparing foreign born Afro Caribbeans to U.S.-born Afro Caribbeans, where U.S.-born Afro Caribbeans have better SES than the foreign-born. The dissertation does not find support for immigrant health assimilation. For BMI and obesity, the foreign-born Black trajectories compared to U.S.-born Blacks indicates patterns of no convergence or divergence. Intergenerationally, while first generation foreign-born Afro Caribbeans had lower obesity rates than second and third generation U.S.-born Afro Caribbeans, U.S.-born Afro Caribbeans had higher rates of obesity than African Americans. A similar intergenerational pattern was found for depressive disorder. Immigrant health assimilation theory predicts convergence of health outcomes between U.S.-born Afro Caribbeans and African Americans, not worse outcomes. The dissertation uncovers two mechanisms that help to explain the observed health trajectories of foreign-born Blacks. The lower first generation foreign-born Afro Caribbean obesity rates compared to second and third generation U.S.-born Afro Caribbeans is explained by differential rates of return on characteristics: the same characteristics provide more obesity protection for the foreign-born than the U.S.-born. Also perceived discrimination was informative in explaining variations in depression. U.S.-born Blacks reported higher levels of perceived discrimination than the foreign-born and foreign and U.S.-born Black women experienced higher depressive symptoms with increased perceived discrimination than men.Item FACTORS ASSOCIATED WITH OBESITY AND PERCEIVED BARRIERS TO WEIGHT MAINTENANCE AMONG SAUDI WOMEN OF REPRODUCTIVE AGE IN JEDDAH CITY.(2016) Alharbi, Muneera MohammedRashed; Jackson, Robert T; Nutrition; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The prevalence of obesity is significantly higher in Saudi women (33.5%) than men (24.1%), however, the information surrounding the risk factors of obesity and barriers to maintaining a healthy weight among Saudi women of reproductive age is deficient due to the limited number of studies that assessed obesity among them. Using a representative sample of 15-49 years old Saudi women attending Jeddah Public Health Care Centers (JPHCCs), this study aims to (1) identify obesity risk factors, (2) explore the barriers to maintaining a healthy weight, and (3) explore the obesity rates and physical activity (PA) levels. A cross-sectional study was conducted in 2014 using a stratified two-stage cluster sampling design comprising 408 Saudi women attending 12 JPHCCs. Body mass index (BMI) and waist circumference (WC) data also were obtained. Data were collected using a structured questionnaire consisting of socio-demographic factors, eating habits (EHs), PA, and perceived barriers to weight maintenance. Of the 408 women evaluated, 33.8% were obese (BMI ≥ 30 kg/m2), 25.1% were abdominally obese (WC ≥ 88 cm), and 31.2% were physically inactive. Age, family history of obesity, and EHs were significant risk factors for both general and abdominal obesity. A high proportion of women faced great barriers in maintaining their weight related to healthy eating (HE) or PA (49.2% versus 50.7%). The most common barriers to HE and PA in the study group were a lack of willpower, skills, knowledge, enjoyment, time, resources, and social influence. Social norms and hot weather had a great impact on the women’s PA level. There was a positive significant association between EHs and PA level and between HE and PA barriers, but no significant associations were found between barriers to maintaining weight and either type of obesity. An intervention program to combat obesity is thus greatly needed, especially one that focuses on eliminating the identified obesity risk factors, and barriers to maintaining a healthy weight.Item High Sucrose, Fructose, and Glucose Diets and Glucocorticoid Dysregulation in Rats(2009) London, Edra; Castonguay, Thomas W; Nutrition; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Approximately two-thirds of U.S. adults are overweight or obese and the prevalence of overweight in children has tripled since 1980. Intake of added sugars has also increased. The etiology of obesity remains unclear and the role of glucocorticoids in obesity is one area of ambiguity. The enzyme 11beta-hydroxysteroid dehydrogenase-1 (11beta-HSD-1) interconverts active and inactive glucocorticoid, thereby regulating intracellular glucocorticoids. Dysregulation of 11beta-HSD-1 in liver and adipose is characteristic of human and animal models of obesity. Hexose-6-phosphate dehydrogenase (H6PDH) is colocalized with 11beta-HSD-1 and determines the set point for 11beta-HSD-1 oxidoreductase activity. In a long-term (10 wk) study, rats given ad libitum access to 16% sucrose solution, chow, and water were fatter than controls, had increased 11beta-HSD-1 mRNA in adipose, suppressed 11beta-HSD-1 mRNA in liver, and increased H6PDH mRNA in both tissues. The primary research questions were as follows: Can high sugar diets induce glucocorticoid dysregulation in the absence of excess adiposity? Does sugar type matter? Energy intake, weight gain, and parameters of lipid and carbohydrate metabolism were measured. Rats were randomly assigned to either ad libitum access to chow and water only (control), or in addition to ad libitum access to either 16% sucrose, fructose, or glucose solution (n=16/gp). After 24h and 1 wk, eight rats per group were randomly selected for sacrifice. Daily caloric intakes among sugar-fed groups did not differ and were higher than the mean intake of the control group. Within 24h, fructose induced increased 11beta-HSD-1 message in mesenteric adipose and liver. Plasma TG and insulin were acutely increased in groups with fructose-containing diets only. All high sugar diets induced suppressed hepatic 11beta-HSD-1 mRNA and protein after 1 wk. Upregulation of H6PDH mRNA observed in response to long-term high sucrose diets may result from increased adiposity and not solely diet. High sugar diets, irrespective of sugar type, initiate glucocorticoid dysregulation in the absence of phenotypic changes associated with obesity. Sucrose, fructose, and glucose have distinct metabolic and endocrine responses. Fructose has the unique ability to induce glucocorticoid dysregulation in liver and adipose in 24h.Item The Relationship of Low Birth Weight and Current Obesity to Diabetes in African-American Women(2007-04-26) Harris, B. Michelle; Lei, David K. Y.; Nutrition; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Aims: (1) To test the fetal origins of chronic disease by examining birth weight, current obesity, and odds of developing type 2 diabetes (T2DM) in African-American women 38-57 years. (2) To assess birth weight and obesity in relation to fasting plasma glucose (FPG). Background: African-American women suffer disproportionately in prevalence and complications of T2DM. According to the fetal origins of chronic disease, T2DM is related to low birth weight with subsequent adult obesity. Several studies have substantiated this hypothesis; none have focused on African-American women. Outcome Measure: Self-reported physician diagnosis of T2DM. Exposure Measures: Birth weight, an indicator for fetal growth; waist-to-hip ratio, a marker for abdominal obesity. Other factors: physical activity, body mass index (BMI), history of gestational diabetes, blood pressure. Design: Retrospective, case-control observational study. Method: Convenience sample of urban African-American women. Cases (n=95) reported a physician diagnosis of T2DM. Controls (n=186), matched on race and age, reported no T2DM diagnosis. To verify control status, participants were screened for elevated FPG (cut-point, <126>mg/dL, as defined by the American Diabetes Association). Vital and family records were sources for birth weight. Current weight, height, and waist and hip circumferences were measured; BMI and waist-to-hip ratio were calculated. Confounding factors were collected on a 68-item questionnaire. Logistic regression analysis tested the proposed model for the odds of having T2DM. Multiple linear regression analysis was employed to assess FPG. Sample size was estimated. Results: The odds ratio for T2DM increased as waist-to-hip ratio increased (OR=1.13, 95% CI=1.08, 1.19, p<.0001). Birth weight did not contribute independently to the model's ability to examine T2DM (OR=0.92, 95% CI=0.74, 1.14, p=.4409). Birth weight and waist-to-hip ratio each contributed independently to assessing FPG. Conclusions: This study found an interaction between birth weight and abdominal obesity when examining T2DM in African-American women: those born small and who subsequently developed abdominal obesity had a greater odds for T2DM. Abdominal obesity, but not birth weight, was independently associated with T2DM. FPG significantly increased with increasing abdominal obesity and decreasing birth weight. African-American women are cautioned to maintain healthy body measures (waist-to-hip ratio <0.80 and BMI <25) to address T2DM.Item Evaluating the Effects of Weight Loss on Exercise-Induced Oxidative Stress in Obese/Overweight Soliders(2006-08-03) Andrews, Anne; Kantor, Mark A; Nutrition; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Exercise is known to increase reactive oxygen species, a condition recognized as oxidative stress. Obese individuals may experience even greater amounts of oxidative stress after exercise compared to normal weight people. It is not clear how weight loss affects exercise-induced oxidative stress in overweight subjects. The objectives of this study were to 1) evaluate the effect of the Army Physical Fitness Test (APFT) on biomarkers of oxidative stress in overweight/obese soldiers 2) determine the effects of dietary antioxidants, fitness level, body composition on exercise-induced oxidative stress, and 3) determine the effect of weight loss on changes in biomarkers of oxidative stress as a result of the APFT. A total of 60 subjects (35 M, 25 F) were recruited. After completing the 1st APFT (n=47), subjects followed a 3-month weight loss program and then completed the 2nd APFT (n=29). Blood measurements of the oxidative stress biomarkers creatine kinase (CK), C-reactive protein (CRP), glutathione peroxidase (GPX), and superoxide dismutase (SOD) were taken pre, immediately after and 24hrs after each exercise test. Dietary antioxidant intake, fitness level and body composition were also assessed at each APFT. After completing the 1st APFT, subjects showed a significant increase in CK and CRP levels immediately post-exercise and in CK at 24hrs post-exercise. There was a significant decrease in GPX immediately post-exercise but no significant change in SOD following exercise. Each of the oxidative stress biomarkers were found to be influenced by the antioxidant vitamins A, C and E, fitness level, total fat mass and total fat percentage. There were also significant interactions between fitness level and vitamins A, C, and E, and between fitness level and total fat mass and total fat percentage. There was no significant effect of attempted weight loss on the exercise-induced changes in the biomarkers, but there were significant changes in BMI, fat mass and fat percentage after the weight loss period. In conclusion, the APFT produced oxidative stress in overweight subjects which was not affected by attempted weight loss. Changes in oxidative stress biomarkers at the different time points were significantly affected by dietary antioxidants, fitness level, and body composition.Item Variations in 11B-Hydroxysteroid Dehydrogenase Type1 in Two Rat Models of Obesity(2006-05-04) Parsons, Erica Zager; Castonguay, Thomas W; Nutrition; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Obesity is an epidemic that has been estimated to cost the United States over $117 billion every year. Glucocorticoids have long been implicated in the maintenance of energy homeostasis due to their involvement with the hypothalamic-pituitary-adrenal axis. 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD-1) is an enzyme that interconverts the glucocorticoids cortisol and cortisone, and their rat counterparts corticosterone and 11-dehydrocorticosterone. We predicted an association between hepatic levels of this enzyme and either genetic obesity or dietary-induced obesity from any of two fat levels (high fat, low fat) or three fat sources (saturated, polyunsaturated, or monounsaturated). Our results indicated that hepatic 11β-HSD-1 is downregulated in genetic obesity, as has been previously found. High fat diets also caused reductions in hepatic enzyme message, although these were not statistically significant. There did not appear to be any effect of fat type.Item The "Get More" Message: Promoting Fast Food to Blacks(2005-04-20) Smith, Nancy Gray; Sawyer, Robin G.; Public and Community Health; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Blacks in the United States suffer disproportionately from overweight and associated health problems, relative to whites. Reasons are complex but environmental factors including fast food promotions may be contributing. This project compares promotional messages in fast food television advertisements targeted to blacks with those targeted to the larger general television audience. The primary promotional message of interest is that suggesting a better value exists through the purchase of larger or additional food items, referred to as the "get more" message. Also examined is the fast food promotional message for low or reduced calorie fare, referred to as the "get less" message. The main study hypotheses test for whether a greater proportion of "get more" food for the money messages, and a lesser proportion of "get less" calorie messages, respectively, are associated with fast food television advertisements featuring blacks, than with fast food television advertisements that do not feature blacks. The portrayal of identifiably black characters in advertisements, especially blacks in dominant roles, is defined in this study as a fundamental black targeting cue. The research method was a content analysis of 311 (138 unduplicated) fast food television advertisements videotaped on the six major U.S. broadcast networks (ABC, CBS, NBC, FOX, UPN, and WB) during one composite week of primetime television. The sample week was constructed over an 8 month period during 2003-2004. Ads were content coded by two teams, respectively, each consisting of one black and one white coder. Hypotheses were analyzed primarily through chi-square tests of association. Key findings are that significantly more "get more" messages were associated with advertisements featuring blacks than advertisements that did not feature blacks, and this association remained strong after controlling for type of restaurant, network, and date aired. Also, significantly fewer "get less" messages were associated with advertisements featuring blacks than advertisements that did not feature blacks. In short, fast food television advertisements featuring blacks were more likely to promote the purchase of larger amounts of food and higher calorie food than advertisements that did not feature blacks. Implications are discussed with respect to community education, policy, and the need for further research.Item THE EFFECTS OF OBESITY ON PLASMA LEVELS OF OMENTIN, A DEPOT-SPECIFIC ADIPOCYTOKINE(2004-08-27) de Souza Batista, Celia Maria; Kantor, Mark; McLenithan, John; Nutrition; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Obesity is a chronic pathological condition and a risk factor for diabetes and cardiovascular disease. It has been demonstrated that adipose tissue functions not only as a fat storage depot but also as an endocrine organ. Omentin is a protein expressed and secreted in adipose tissue that increases insulin-stimulated glucose transport. To further elucidate omentin's physiological function, its levels were measured by quantitative western blotting in plasma from 44 healthy nondiabetic volunteers (22 women, 22 men). Participants were organized into sibling pairs based on discordant BMI (3-12 Kg/m2). Lean subjects had significantly higher omentin levels than obese/overweight subjects (independent of sex), and significantly higher omentin levels were detected in women compared to men. Omentin levels were inversely correlated with BMI and positively correlated with HDL levels. These data suggest that omentin may play a physiological role in the pathogenesis of obesity-dependent insulin resistance.