UMD Theses and Dissertations
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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 Associations between Urinary Phthalates and Metabolic Syndrome in NHANES 2005-2010(2015) Haque, Mefruz Salwa; Dallal, Cher M; Epidemiology and Biostatistics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Phthalates, commonly used to make plastics more durable, are a group of endocrine disrupting chemicals (EDC), with potential for adverse metabolic consequences. Associations between exposure to 13 phthalate metabolites and the prevalence of metabolic syndrome (MetS) were examined among 5,409 U.S adults ≥ 18 years of age, who participated in the National Health and Nutrition Examination Survey from 2005-2010. MetS was assessed using clinical and questionnaire data. Odds Ratio (OR) and 95% Confidence Intervals (CI) adjusting for age, creatinine and key confounders, were estimated with multivariable logistic regression. Positive associations were observed between individual phthalate metabolites and MetS: (MCOP OR=1.31, 95% CI=1.40, 1.64, p-trend<.01; MCPP OR=1.39, 95% CI=1.09, 1.77, p-trend=0.01). In gender stratified analyses, findings with MCOPP and MCPP were restricted to women only. Phthalate metabolites may increase the prevalence of MetS; however, further studies are needed to better understand the role of EDCs in the development of MetS.Item HYPERLEPTINEMIA, METABOLIC SYNDROME, AND MORTALITY IN OLDER ADULTS(2010) Mishra, Suruchi; Sahyoun, Nadine R; Mehta, Mira; Nutrition; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Background: Abdominal adiposity and fat mass increase with aging, and as does insulin resistance which is frequently associated with hyperleptinemia and leptin resistance. Serum leptin may predict risk of metabolic syndrome and mortality among older adults. Objectives: The objectives of the present study were to evaluate the relationship of serum leptin with risk of metabolic syndrome and mortality and to examine these associations in relation to the measures of body adiposity and proinflammatory cytokines. The influence of leptin receptor (I/D) gene polymorphism on diabetes as a contributing cause of mortality was also examined. Gender specific serum leptin cut off values as a biomarker for the risk of metabolic syndrome were determined. Design: The Health, Aging and Body Composition (HABC) study is a prospective cohort of 3,075 older adults aged 70 to 79 years. Body composition, demographic information, biochemical variables including, markers of systemic inflammation, and genetic variation were assessed in detail. Results: Women in quintile 2, 3, 4 and 5 of serum leptin were at significantly lower risk for metabolic syndrome as compared to those in quintile 1 after controlling for confounders. Serum leptin was independently associated with risk of metabolic syndrome after sequentially adjusting for demographic variables (p<0.0001), fat depots (p=.0024), and proinflammatory cytokines (p=.0098) in women. Among men, the association between serum leptin and risk of metabolic syndrome was explained by body adiposity. Women in quartile 2 and 3 of serum leptin were at lower risk than women in quintile 1 for all-cause mortality and mortality from cardiovascular disease independent of body fat and proinflammatory cytokines. Additionally, elevated level of serum leptin was associated with increased risk for diabetes as a contributing cause of mortality for both genders after sequentially adjusting for potential confounders, body fat and proinflammatory cytokines. Significant interaction was found between leptin receptor genotype and total percent fat (p=0.008) in association with diabetes as a contributing cause of mortality among women. The cut off serum leptin level that suggests the possible risk of metabolic syndrome was determined to be 6.45 ng/ml with 60% sensitivity and 63% specificity among men and 18.25 ng/ml with 55% sensitivity and 62% specificity among women. Conclusion: Elevated levels of serum leptin may be associated with increased risk of metabolic syndrome and risk of diabetes as a contributing cause of mortality among older women. However, intermediary levels of serum leptin may lower the risk of all-cause mortality and mortality from CVD, suggesting a paradoxical association of serum leptin with cardiovascular risk factors and mortality from CVD among older womenItem The Effects of Low-Fat Diet and Exercise on C-Reactive Protein and Metabolic Syndrome: Findings from a Randomized Controlled Trial(2008-07-09) Camhi, Sarah Michelle; Young, Deborah R; Kinesiology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Background: Low-fat diet (D) and exercise (E) are recommended for reducing cardiovascular disease risk. However, the independent and combined effects of D and E on C-reactive protein (CRP) and metabolic syndrome (MS) are unknown. Purpose: The purpose of this dissertation was to examine the changes in CRP and MS between control (C), D, E and diet plus exercise (D+E). Methods: Men (n=197) and postmenopausal women (n=180) with elevated low-density lipoprotein cholesterol and reduced high-density lipoprotein cholesterol, were randomized into a one-year trial with four groups: C, D, E or D+E (Stefanick et al., 1998). Weight loss was not an intervention focus. This secondary data analysis evaluated stored plasma samples for high-sensitivity CRP. MS prevalence was retrospectively found using the NCEP-ATP III definition. CRP change (ΔCRP) was examined between intervention groups using ANCOVA. Differences between groups for MS at follow-up were retrospectively investigated using logistic regression. All analyses were stratified by gender and controlled for baseline values, body fat change and other appropriate covariates. Results: In women, ΔCRP was different between D+E vs. C (-0.7 ± 0.33 mg/L, p = 0.04) and D+E vs. E (-0.9 ± 0.32 mg/L, p = 0.004). Women also had a decrease in CRP within D+E (Δ log CRP 0.2 ± 0.035 mg/L; p = 0.0002). After the intervention, ΔCRP did not differ for men between or within treatment groups. MS at follow-up was not different between C, D, E or D+E in either men or women. In women with MS, ΔCRP was different between D+E vs. C (-1.3 ± 0.43 mg/L; p = 0.006), D+E vs. E (-1.1 ± 0.44 mg/L; p = 0.02), and D vs. C (-1.2 ± 0.43 mg/L; p = 0.009). In women with MS, CRP decreased from baseline within D+E (Δ log CRP 0.2 ± 0.039 mg/L; p=0.0008). At follow-up, there were no differences between or within groups for ΔCRP in men with MS, or men without MS and women without MS. Conclusion: D and D+E may be effective treatments for reducing CRP in women with MS. Further studies are needed to replicate results and clarify the influence of gender.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.