PhD Dissertation / Obesity is a major risk factor for type 2 diabetes (T2D) and non-alcoholic fatty liver disease (NAFLD), and is attributed to excess energy intake in comparison to energy expenditure. Therapeutics that reduce energy intake in obesity have limited efficacy, with weight loss typically reaching less than 10% of initial body mass, leading to efforts to uncover new therapies that may increase energy expenditure. Unlike lipid-storing white adipose tissue, brown and beige adipose tissues undergo futile cycling, oxidizing lipids and carbohydrates thereby increasing energy expenditure. With obesity, the metabolic activity of brown and beige adipose tissue is reduced, suggesting that restoring adipose tissue thermogenesis may represent a new means to enhance energy expenditure. Previous studies in mice have shown that peripheral serotonin synthesis by the enzyme tryptophan hydroxylase 1 (Tph1) inhibits adipose tissue thermogenesis and contributes to the development of obesity, insulin resistance and NAFLD. However, the primary Tph1 expressing tissue(s) inhibiting adipose tissue futile cycling is not known. In this thesis, we genetically removed Tph1 in mast cells of mice and discovered that this elevated beige adipose tissue activity protecting mice from developing high-fat diet induced obesity, insulin resistance and NAFLD. In contrast to these findings, genetic deletion of Tph1 in adipocytes did not result in protection from obesity, suggesting that mast cells are the primary source of serotonin that inhibits white adipose tissue thermogenesis. Lastly, to determine the importance of adipose tissue thermogenesis in mediating the beneficial metabolic effects of reduced Tph1, mice were housed at thermoneutrality, blocking the requirement for adipose tissue thermogenesis. Under these conditions, mice lacking Tph1 had comparable brown and beige adipose tissue metabolic activity, energy expenditure and adiposity, however, surprisingly, were still protected from insulin resistance and NAFLD. The studies in this dissertation have discovered that mast cell Tph1 is critical for inhibiting adipose tissue thermogenesis and that serotonin plays an important role in promoting NAFLD, independently of its inhibitory effects on adipose tissue thermogenesis. Collectively, these findings further define the roles of serotonin in regulating whole-body energy metabolism, providing critical clues and mechanistic insights for potential therapies to mitigate metabolic diseases. / Dissertation / Doctor of Philosophy (Medical Science) / Obesity, type 2 diabetes (T2D) and non-alcoholic fatty liver disease (NAFLD) can develop when caloric intake exceeds expenditure. In contrast to lipid-storing white fat, brown and beige fat burn calories. Serotonin is a hormone that reduces the burning of calories in fat, therefore finding ways to inhibit its effects on fat tissue without altering serotonin in the brain may lead to new therapies for obesity and other related diseases. In this thesis, we examined potential sources of serotonin that might inhibit the burning of calories in adipose tissue of mice. By reducing the synthesis of serotonin in a white blood cell called mast cells, but not fat cells, mice were protected from obesity, pre-diabetes and NAFLD due to increased activity of beige fat. Moreover, when we kept mice in a warm environment, thus reducing the need for mice to burn calories in brown and beige fat, this eliminated the effects of serotonin to promote obesity, but not pre-diabetes and NAFLD. These studies have identified how serotonin generated from mast cells inhibits the burning of calories in adipose tissue, a finding that may lead to new therapies for obesity, T2D and NAFLD.

Type 2 diabetes (T2D) is characterized by impaired beta cell function. The generation of various types of cellular stresses, including oxidative stress and ER stress, and the induction of cellular senescence can contribute to beta cell dysfunction. Recent studies have demonstrated associations between petrochemical exposure and beta cell dysfunction, particularly through induction of cellular stress. One class of compounds, commonly found in crude oil, are sulphur-containing heterocyclic aromatic compounds (S-HACs). S-HACs have been previously demonstrated to induce cellular stress in mammalian cells. This thesis aims to determine if S-HACs can induce cellular stress in beta cells and, consequently, impair beta cell function, particularly insulin production. Rat pancreatic beta cells, INS-1Es, were treated with two commonly occurring S-HACs, BNT(2,3D) and DBT, at doses which reflect non-occupational exposure levels. Upon treatment, various functional assays and qPCR experiments were performed for examining glucose uptake, ROS production, cellular senescence, ER stress and intracellular insulin production. It was observed that both BNT(2,3D) and DBT significantly increased glucose uptake and ROS production in the beta cells and upregulated the mRNA expression of various ER stress markers. In addition, BNT(2,3D) also induced cellular senescence, likely through a p53-independent pathway. This suggests that S-HACs may induce oxidative stress and ER stress in exposed beta cells, and some S-HACs may cause irreversible cell cycle arrest in response to these cellular stresses. However, intracellular insulin content in the INS-1Es was not altered by exposure to either S-HAC, suggesting that S-HACs may not impair insulin production. Nevertheless, the significant accumulation of ROS in S-HAC-exposed beta cells and the subsequent induction of cellular senescence by some S-HACs may alter other important beta cell functions, including mitochondrial function and insulin secretion, which could lead to the development of T2D; suggesting the potential for S-HACs to be novel beta cell toxicants. / Thesis / Master of Science (MSc)

Dietary soy isoflavones have been shown to ameliorate insulin resistance and Type 2 diabetes. However, many in vitro studies used supra-physiological concentrations of individual isoflavones that make it difficult to interpret the results as potential mechanisms in vivo. Since the insulin-sensitizing effects of thiazolidinediones, anti-diabetic drugs, have been shown to be mediated through activation of peroxisome proliferators-activated receptor gamma (PPARγ), the key transcription factor for adipocyte differentiation, we examined the effects of the two main soy isoflavones genistein and daidzein either as individual compound or combined on adipocyte differentiation and PPARγ expression, as well as whether the Wnt/β-catenin signaling pathway is the underlying molecular mechanism. In 3T3-L1 cells, genistein and daidzein significantly enhanced adipocyte differentiation. Similarly the expression of PPARγ increased particularly at 20 µmol/L. The stimulatory effect is greater when the two isoflavones are combined, indicating a synergistic effect. Genistein and daidzein also increased the relative abundance of insulin-responsive glucose transporter 4 (GLUT4) mRNA with a greater effect when combined. Wnt10b expression was not affected by soy isoflavones treatments, while Wnt5b expression was only increased by the combination of genistein and daidzein. Our results suggest, that the combination of soy isoflavones has a greater effect in increasing the newly formation of adipocytes that are highly insulin-sensitive via an increase in PPARγ expression as well as increasing the expression of GLUT4. However, genistein and daidzein actions on Wnt signaling remain unclear. These data further support the epidemiological findings for the beneficial effect of soy consumption on insulin sensitivity.

In the U.S., diabetes mellitus cases have been increasing, from 25 million in 2010 to 29 million in 2012. Healthy People 2020, the U.S. National Health Agenda, has established specific goals and objectives for diabetes. In the U.S., prevalence of pre-diabetes and diabetes for adult Hispanics was 38% and 12%, respectively, in 2012. The total estimated diabetes cost in the U.S. has been increasing, from $176 billion in 2007 to $245 billion in 2012. The current study had two research hypotheses; the formative phase was expected to demonstrate a need for a community-based Type 2 Diabetes Mellitus (T2DM) self-management intervention for Spanish-speaking Hispanics. Random Control Trial (RTC) was expected to demonstrate the potential impact in preventing and managing T2DM. Methods. A community-based lifestyle education curriculum was translated into Spanish, and adapted to Hispanic culture. This study includes three phases: 1) a formative phase; 2) a two-group pilot RCT with Hispanic Living with Diabetes (HBLD) and a delayed treatment condition; and 3) post-HBLD focus groups held with three participating groups of HBLD. Results. Of 60 participants screened in the formative phase, 62% had A1c > 5.7%, and 75% did not have medical insurance. Of 6 participants who completed the pilot, A1c decreased for all six participants. Of 67 participants screened in phase 2, 61% had A1c > 5.7%. Of 30 HBLD participants in the RCT, baseline versus 3-month mean A1c increased 0.2 for the delayed control group (n = 10) and did not experience any change for the intervention group (n = 11). The difference in A1c change from baseline to follow up between treatment groups was not statistically significant (Kruskal Wallis, p < 0.05). Diabetes knowledge and SCT variables change from baseline to follow-up between groups were not statistically significant. Major themes identified in focus group discussions included barriers to access to health and nutrition services, the value of having a Spanish-speaking Hispanic as a health educator, and barriers to recruiting community members as promotoras. Implications. HBLD has potential to reduce complications of diabetes among Hispanic participants by providing education to those who may not otherwise have access to it. / Ph. D.

STUDY 1 Aim: To compare the effects of Roux-en-Y gastric bypass (RYGB) and laparoscopic adjustable gastric banding (LAGB) on changes in bone mineral density (BMD), weight loss and blood biomarkers related to bone turnover, hormonal, and nutrient status. Subjects: Nine bariatric surgery patients. Methods: Patients had a DXA bone scan and fasting blood draw at baseline, three, and six months following surgery. Results: RYGB patients had greater weight loss vs. LAGB at both three (mean loss: 19 vs. 9%) and six months (26 vs. 11%), p<0.01. RYGB patients lost an average of 7% hip BMD at six months. Hip BMD loss at six months was correlated to decreased leptin (r=0.88) and increased adiponectin (r=-0.82), p<0.05. Bone turnover was indicated by elevated serum bone biomarkers after surgery. Conclusions: Research with larger sample sizes is warranted to better evaluate potential implications for late-life osteoporosis risk following bariatric surgery. STUDY 2 Aim: To determine repeatability for IMAT and muscle density, to evaluate the distribution of foreleg muscle and fat indices measured by pQCT and to determine predictors of muscle density and type-2 diabetes risk. Subjects: 82 women with varying BMI and physical activity levels. Methods: Subjects had DXA and pQCT bone scans, a fasting blood draw, and completed a 4-day physical activity record. Results: Fat and muscle distribution in the foreleg was highly correlated to total and central body adiposity. The pQCT device reliably measured muscle density (CV=0.8%), thus justifying use as surrogates for IMAT. Muscle density was positively related to physical activity (r=0.29; p<0.05) and negatively associated with markers of fat distribution and risk for type-2 diabetes [HOMA-IR (r=-0.44, p<0.01)]. Conclusions: Further research is necessary to determine whether specific fat or muscle depots can be targeted through exercise training to help with the prevention and treatment of obesity or type-2 diabetes. / Ph. D.

Type 2 diabetes affects more than one-quarter of older adults in the United States. Many older adults manage type 2 diabetes (T2D) in the context of marriage, although few studies have acknowledged the effect the illness has on marital quality. The current study examined how the presence of T2D in later life relates to marital quality, and how positive health behaviors--diet, physical activity, and sleep--can moderate the relationship between T2D and marital quality. Data from the 1,200 married older adults in the Life and Family Legacies study were used to estimate moderation models using structural equation modeling in Mplus. Results indicated that T2D is associated with declines in marital quality. In addition, lower glycemic diets moderate the association such that healthy diets (higher intake of low glycemic indexed foods) buffer the impact on T2D on marital quality. These findings suggest T2D effects social relationships, and that positive health behaviors, especially healthy diets, can help buffer the negative association between T2D and marital quality. These results have implication for health care providers who can view patients' diabetes management in the context of their health behaviors and social relationships to best provide resources for management.

Pre-existing diabetes, type 1 or type 2 diabetes, can be a challenge to manage during pregnancy. Due to the increased fetal and obstetrical risks from hyperglycemia, women are advised to keep blood glucose as close to normal as possible. Diabetes distress is the negative emotional experience of managing diabetes, with prevalence between 20-50% in non-pregnant adults with diabetes. As diabetes distress during pregnancy has not been well studied, the purpose of this study was to use a sequential explanatory mixed methods approach to understand the extent and impact of diabetes distress. This was achieved by first conducting a cross-sectional quantitative study with 76 women pre-existing diabetes. Diabetes distress was measured with the Problem Area in Diabetes (PAID) Scale and a score of 40 or higher indicated high diabetes distress. Women with both types of diabetes and high and low PAID scores were recruited to the second strand, which was an interpretive description qualitative study. Semistructured interviews were conducted with 18 women discuss their experiences of diabetes distress and managing diabetes in pregnancy. In the mixed methods analysis, it was observed that while diabetes distress was seen in 22.4% of women, the majority of women who took part in the qualitative interviews described themes of diabetes distress whether they had a high or low PAID distress score. Current diabetes distress tools are not validated for pregnancy, and qualitative findings indicate that diabetes distress during pregnancy is uniquely defined by worries for the baby. Development of a pregnancy-specific diabetes distress tool for integrated screening during pregnancy would be beneficial to better capture distress rates in this population. The counterpart to the qualitative findings of diabetes distress were findings of resiliency demonstrated by the participants. Further research is needed to better understand appropriate interventions to increase resiliency in pregnancy to mitigate diabetes distress. / Thesis / Doctor of Philosophy (PhD) / Women with type 1 and type 2 diabetes require intensive blood sugar control while they are pregnant in order to have a healthy pregnancy. While it is known that diabetes during pregnancy can be challenging emotionally, there is limited information about how diabetes distress affects this group. The aim of this thesis is to understand how many women report diabetes distress during pregnancy and how they perceive diabetes distress. This thesis includes a synthesis of the literature on mental health and psychosocial well-being, a study that administered surveys at one time during pregnancy, a study that used interviews to ask the same women about their experience of pregnancy with diabetes, and a study that mixed the survey and interview results. The results illuminate the extent to which diabetes distress affects women during pregnancy, informing future research that will help better screen for diabetes distress and improve clinical care during pregnancy.

In chapter 1, a comprehensive meta-analysis is conducted to synthesize the effectiveness, cost, and cost-effectiveness of lifestyle diabetes prevention interventions and compare effects by intervention delivery agent and channel. Sixty-nine studies meet inclusion criteria. The results show that participants receiving intervention with nutrition education experienced a reduction of 2.07 kg (95% CI: 1.52 to 2.62; p<0.001; 95% CI: 88.61% to 92.87%) in weight at 12 months with effect sizes over time ranging from small (0.17, 95% CI: 0.04 to 0.30; p=0.012; 95% CI: 80.42% to 91.14%) to medium (0.65, 95% CI: 0.49 to 0.82; p<0.001; 95% CI: 98.52% to 98.94). In sum, lifestyle interventions are effective in reducing body weight and glucose-related outcomes. Dietitian-delivered interventions achieve greater weight reduction compared to those delivered by other personnel. In chapter 2, this study attempts to examine the effects of household relative deprivation on children's health outcomes. A modified household production model is developed with energy intake, energy expenditure and a composite good as main inputs in the health production. A two-stage Stackelberg game facilitates the need to model the parent-child interaction which follows similar structure as You and Davis (2011). We use three measurements of relative deprivation based on per capita household income and four reference groups based on combinations of geographic and demographic characteristics. The results show that relative deprivation is negatively associated with child health. In chapter 3, we define "process benefits" as the direct effect on utility from engaging in an activity and examine how "process benefits" associated with food activities, both uptake and duration, are related to factors such as socio-economic status and demographics. A household production model is utilized to demonstrate the vital role of process benefits in home food production and the implications it will have for nutrition based policies targeting resources. The results display that the process benefits are associated with some demographic characteristics. This implies that shortfalls in food activities are not simply a matter of technology or resource shortfalls, but also reflect disutility associated from these activities which in turn will attenuate the impact of policies design to merely address resource shortfalls. / Ph. D. / Evaluation of programs is a vital part in health economics for it is important in understanding the effect and limitation of a program from an economic perspective. Three applications are included in this dissertation. The first application is to synthesize the overall effectiveness of diabetes prevention program including nutrition education; the second application is to evaluate if there is a negative association between relative deprivation and children’s health outcomes; the third one is to explain the small effect of nutrition policy, such as SNAP. Type 2 diabetes (T2D) has increased significantly worldwide, leading to substantial increases in total economic costs in the US. A proliferation of studies have attempted to translate lifestyle interventions into clinical and community practice in an attempt to halt this growing public health epidemic. Therefore, there is a need to investigate the effectiveness of interventions including nutrition education for diabetes prevention. The results show that diabetes prevention program with nutrition education is effective in reducing body weight and glucose-related outcomes. China has reached the fastest rate of growth in economy since the implementation of reform and become the world’s second largest economy. However, improvement in health fails to accompany the massive growth in material living standards for the Chinese population. This observation prompts us to investigate the relative deprivation hypothesis. The results show that children who are more relatively deprived have poor health outcomes. Food assistance programs, e.g., Supplemental Nutrition Assistance Program (SNAP), have been developed to improve people’s health. However, the nutrition level recommended by those programs are still not met for the targeted population. The results show that respondents who enjoy cooking spend more time on activities related to food production, such as food preparation, presentation and clean up. And the small effect of nutrition policies is due to the disutility from the process of food production.

No / Cardiovascular disease is the principal cause of death in patients with type 2 diabetes (T2DM). Exposure of the vasculature to metabolic disturbances leaves a persistent imprint on vascular walls, and specifically on smooth muscle cells (SMC) that favours their dysfunction and potentially underlies macrovascular complications of T2DM. Current diabetes therapies and continued development of newer treatments has led to the ability to achieve more efficient glycaemic control. There is also some evidence to suggest that some of these treatments may exert favourable pleiotropic effects, some of which may be at the level of SMC. However, emerging interest in epigenetic markers as determinants of vascular disease, and a putative link with diabetes, opens the possibility for new avenues to develop robust and specific new therapies. These will likely need to target cell-specific epigenetic changes such as effectors of DNA histone modifications that promote or inhibit gene transcription, and/or microRNAs capable of regulating entire cellular pathways through target gene repression. The growing epidemic of T2DM worldwide, and its attendant cardiovascular mortality, dictates a need for novel therapies and personalised approaches to ameliorate vascular complications in this vulnerable population.

Yes / Type 2 diabetes (T2DM) confers increased risk of endothelial dysfunction, coronary heart disease, and vulnerability to vein graft failure after bypass grafting, despite glycaemic control. This study explored the concept that endothelial cells (EC) cultured from T2DM and nondiabetic (ND) patients are phenotypically and functionally distinct. Cultured human saphenous vein- (SV-) EC were compared between T2DM and ND patients in parallel. Proliferation, migration, and in vitro angiogenesis assays were performed; western blotting was used to quantify phosphorylation of Akt, ERK, and eNOS. The ability of diabetic stimuli (hyperglycaemia, TNF-α, and palmitate) to modulate angiogenic potential of ND-EC was also explored. T2DM-EC displayed reduced migration (~30%) and angiogenesis (~40%) compared with ND-EC and a modest, nonsignificant trend to reduced proliferation. Significant inhibition of Akt and eNOS, but not ERK phosphorylation, was observed in T2DM cells. Hyperglycaemia did not modify ND-EC function, but TNF-α and palmitate significantly reduced angiogenic capacity (by 27% and 43%, resp.), effects mimicked by Akt inhibition. Aberrancies of EC function may help to explain the increased risk of SV graft failure in T2DM patients. This study highlights the importance of other potentially contributing factors in addition to hyperglycaemia that may inflict injury and long-term dysfunction to the homeostatic capacity of the endothelium.