Este estudo, com delineamento tipo caso-controle, teve como proposta testar as hipóteses de que a amamentação ao seio é um fator de proteção para o DMID e o leite de vaca, introduzido precocemente na alimentação infantil, é um fator de risco para a doença. Os casos foram identificados na Associação de Diabetes Juvenil de São Paulo e no ambulatório de Endocrinologia da Escola Paulista de Medicina. Trezentos e quarenta e seis casos, com idade inferior a 18 anos no momento da entrevista, foram comparados com 346 controles pareados aos casos segundo sexo, idade e local de residência. Foram consideradas como variáveis de principal interesse a duração do aleitamento exclusivamente ao seio, a idade da introdução de alimentos lácteos na dieta e ter recebido leite em pó na maternidade. Foram consideradas como variáveis de controle as idades da mãe e do pai no momento do nascimento da criança, o histórico da mãe de rubéola congênita, a duração da gestação, o peso e o comprimento ao nascer, a situação de vacinação, os antecedentes relativos a doenças viróticas da criança, o histórico da criança de episódios graves de diarréia, a data da insulinoterapia, os antecedentes familiares de DMID e DMNID, a renda familiar per capita e a ordem de nascimento da criança. Utilizaram-se o teste t de Student pareado para a comparação das médias das variáveis cujos valores têm distribuição normal e o teste pareado dos sinais dos postos de Wilcoxon para as demais, a técnica de tábua de vida atuarial para se conhecer, aos 7 e aos 60 dias, a proporção de crianças ainda em aleitamento exclusivamente ao seio e sem introdução de alimentos lác- teos. O modelo de regressão logística condicional foi utilizado tanto para as análises da gradação dos odds ratios como para ajustar os efeitos sobre o DMID das três variáveis de interesse a possíveis variáveis de confusão. Os resultados encontrados neste estudo indicam que são fatores de risco para o DMID a ausência de aleitamento exclusivamente, especialmente durante a primeira semana de vida (OR = 2,13, IC: 1,28 - 3,55) e a idade da introdução de alimentos lácteos, especialmente quando esses alimentos são introduzidos durante os primeiros sete dias de vida (OR = 2,29; IC: 1,37 - 3,83). / This case-control study aimed to test the assumption that breast feeding protects against insulin-dependent diabetes mellitus, and that the early introduction of cow milk into the infant diet is a risk factor for the disease. The cases were identified in the Juvenile Diabetes Association of São Paulo, and in the Out-patients Endocrinology Department of the Escola Paulista de Medicina. Three hundred and forty-six cases among patients younger than eighteen years old at the time of the interview were compared with 346 paired control cases for sex, age and place of residence. The main variables were the duration of exclusive breast feeding , the age at which milk products were introduced into the diet, and whether powdered milk was given in the maternity unit. The ages of the parents when the child was born, history of congenital rubella in the mother, duration of gestation, weight and height at birth, vaccination status, the child\'s viral disease history, the child\'s history of severa attacks of diarrhea, the date of insulin therapy, previous familial history of insulin-dependent diabetes mellitus and non-insulin-dependent diabetes mellitus, the per-capita income of the family, and the order of birth of the child. Student\'s paired test was used to compare the mean values of variables with normal distribution, and Wilcoxon\'s signed ranks test was used for all other variables. The actuarial life table technique was used at 7 and 60 days in order to determine the proportion of children still being exclusively breast fed without the introduction of milk products. The conditional logistical regression method was used in dose-response analyses of the odds ratio and to adjust for the effect of the three variables of interest and possible confounding variables on insulin-dependent diabetes mellitus. The findings of this study indicate that the lack of exclusive breast feeding is a risk factor to insulin-dependent diabetes mellitus, particularly during the first week of life (OR=2.13; IC: 1.28-3.55) and that the age at introduction of milk products is a risk factor for the disease, particularly when these products are introduced during the first seven days of life (OR=2.29; IC: 1.37 -33.83).

Type 2 diabetes is a metabolic disease marked by an abnormally high level of glucose (sugar) in the blood. Type 2 diabetes is now reaching an epidemic level with more than 30 million adults in the United States afflicted and 1.5 million new cases documented every year. Type 2 diabetes is linked with obesity, heart disease, hypertension, and liver disease, and individuals with type 2 diabetes are at an increased risk for heart failure, stroke, blindness, kidney failure, and amputation. According to the Centers for Disease Control and Prevention, more than $245 billion was spent in the United States in 2012 on medical expenses related to diabetes and despite that, nearly a quarter of a million Americans are losing their lives due to this disease each year. Indeed, type 2 diabetes is one of the leading causes of death in the United States and worldwide; its prevalence has almost doubled in the last 35 years, from 4.7% of the total population in 1980 to 8.5% in 2014. Consequently, more than 400 million people are at high risk for severe health problems and complications, poor quality of life, and early death. Research such as the Diabetes Prevention Program (DPP), the Finnish Diabetes Prevention Study (DPS), the Vesterbotten Intervention Program (VIP), and the Diabetes Prevention Program Outcome Study (DPPOS) suggests that type 2 diabetes can be delayed, and even prevented, with a lifestyle behavioral modification program that includes healthy eating and/or exercise. Therefore, focus has been shifted from management to prevention. An early manifestation of dysfunction in the progression of type 2 diabetes is insulin resistance, a metabolic impairment associated with obesity. Indeed, it is estimated that ~90% of people with type 2 diabetes also are obese. The link between insulin resistance and obesity is well-established; however, the mechanistic basis(es) underpinning this link is/are still debated with multiple candidate molecules, systems, and pathways potentially involved. One theory that has gained traction in recent years suggests that type 2 diabetes, and the insulin-resistant state that predates it, are rooted in dysfunctional lipid metabolism (i.e., a reduced capacity to use lipid for energy production in circumstances where lipid would be preferred, such as in the basal fasting condition, after a high-fat meal, and during light- and moderate-intensity exercise). However, there are conflicting findings regarding the degree to which the ability to oxidize lipid during these circumstances is compromised for individuals with the overweight/obesity that is associated with the disease progression. The reason(s) for this ambiguity is/are unclear but might have to do with a number of factors that were poorly controlled when substrate selectivity (i.e., lipid vs. carbohydrate oxidation rates) were compared between normal-weight individuals and those with the overweight/obese condition. These include: (a) acute energy balance and macronutrient composition of the diet; (b) the intensity and duration of the exercise bout; and (c) subject characteristics including the amount of muscle tissue they possess, their cardiorespiratory fitness level, and, perhaps most importantly, their insulin-sensitivity state. The purpose of this dissertational work is to: (a) help to resolve this ambiguity by identifying the degree to which conflicting results that have been reported might be explained by factors that were left unaccounted for and/or inadequately controlled in previous research; and (b) compare substrate selectivity in normal-weight individuals and those with the overweight/obesity condition during a physiologically-equivalent exercise challenge with the aforementioned factors rigidly controlled.

2 型糖尿病(T2D)的發展歷史悠久，但導致T2D 患者胰島素抵抗的確切病理還沒有完全理解。骨骼肌佔大多數(70-80%)的胰島素引導的葡萄糖的吸收，所以它一直是胰島素抵抗的研究焦點。許多 T2D 患者的骨骼組織顯示線粒體功能障礙，但線粒體功能障礙和胰島素抵抗之間的關係尚不清楚還在辯論中。在這個項目中，這種關係是通過研究游離脂肪酸(FFA)( 24 小時處理)對 C2C12 小鼠骨骼肌細胞的效果來闡明。 / 免疫印記法顯示FFA 誘導胰島素抵抗，結合二維電泳和質譜分析的蛋白質組學研究發現FFA 有抑制糖酵解，增加β-氧化作用，沒有改變檸檬酸循環和抑製氧化磷酸化的作用。FFA 抑制電子傳遞鏈的幾個組成部分，揭示線粒體功能障礙，背後的原因可推測為FFA 增加令β-氧化作用增加，但沒有協調改變率檸檬酸循環，導致積累不完全β-氧化的中轉體，導致線粒體過載，最終導致胰島素抵抗。 / There is a long history of Type 2 diabetes (T2D) research development, but the exact pathology leading to insulin resistance of T2D is still not fully understood. T2D is frequently characterized by tissue insulin resistance and it is often associated with an elevated concentration of palmitic acid (PA, a major kind of dietary fatty acid) in serum. Due to this correlation, much of the effort in the field had been concentrated on the effect of PA in insulin action and glucose metabolism, and how elevated PA could possibly cause insulin resistance in specific tissues. / Skeletal muscle accounts for the majority (70-80%) of insulin-mediated glucose uptake, so it has been the focus of insulin resistance studies. Many T2D patients having elevated serum free fatty acid (FFA, where PA is a kind of FFA) also show mitochondrial dysfunction in their skeletal tissue, but the relationship between mitochondrial dysfunction and insulin resistance in skeletal muscle remains unclear and under debate. In this project, the three-party relationship was elucidated by studying the effect of 24hrs of incubation of palmitic acid (PA) on skeletal muscle using C2C12 mouse skeletal cells as model. / PA-treated C2C12 cells show reduction in insulin-stimulated Akt phosphorylation when compared with untreated C2C12 cells. Comparative proteomic study for both total proteins and mitochondrial proteins with 2D gel electrophoresis and mass spectrometry unveil, when compared with untreated cells, PA-treated C2C12 cells show down-regulation in enzymes involved in glycolysis(e.g. glyceraldehyde-3-phosphate dehydrogenase, phosphoglycerate kinase, fructose-bisphosphate aldose A), up-regulation in enzymes involved in beta-oxidation(e.g. 3-ketoacyl-CoA thiolase, 3-hydroxyacyl-CoA dehydrogenase), and down-regulation in proteins involved in oxidative phosphorylation(e.g. ATP synthase subunits, NADH-ubiquinone oxidoreductase 75kDa subunit, cytochrome b-c complex subunit 1). / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Lam, Chor Kwan. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 69-78). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts also in Chinese. / Thesis/Assessment Committee --- p.i / Declaration --- p.ii / Abstract (in English) --- p.iii / Abstract (in Chinese) --- p.v / Acknowledgments --- p.vi / Table of Contents --- p.vii / List of Abbreviations --- p.x / List of Figures --- p.xiii / List of Tables --- p.xiv / Chapter 1. --- Literature review --- p.1 / Chapter 1.1. --- Introduction to diabetes mellitus --- p.1 / Chapter 1.1.1. --- Definition and prevalence --- p.1 / Chapter 1.1.2. --- Diagnosis and classification --- p.2 / Chapter 1.1.3. --- Symptoms and complications --- p.4 / Chapter 1.1.4. --- Causes and risk factors --- p.5 / Chapter 1.1.5. --- Prevention and treatment --- p.6 / Chapter 1.2. --- The role of muscle tissue in pathophysiology of T2DM --- p.7 / Chapter 1.3. --- Insulin receptor substrate-1 and Fatty acids-induced insulin resistance --- p.15 / Chapter 1.4. --- Introduction of proteomics --- p.18 / Chapter 1.4.1. --- The application of proteomics in disease discovery --- p.18 / Chapter 1.4.2. --- Application of Proteomics --- p.19 / Chapter 1.4.3 --- Two-dimensional gel electrophoresis --- p.20 / Chapter 1.4.4 --- Organelles proteomics --- p.21 / Chapter 1.4.5. --- Mass spectrometry --- p.22 / Chapter 1.4.6 --- Application of proteomic technology in disease pathology --- p.24 / Chapter 1.4.7 --- Current challenges --- p.25 / Chapter 1.5 --- Objectives --- p.27 / Chapter 2 --- Materials and Methods --- p.28 / Chapter 2.1 --- Fatty acid preparation --- p.28 / Chapter 2.2 --- Cell culture --- p.28 / Chapter 2.2.1 --- Treatment of C2C12 myotubes with Palmitic acid --- p.28 / Chapter 2.2.2 --- MTT assay for viability measurement --- p.29 / Chapter 2.2.3 --- Determination of the IC₅₀ values --- p.31 / Chapter 2.3 --- Proteomic analysis of C2C12 cells with and without PA treatment --- p.32 / Chapter 2.3.1 --- Protein sample preparation from C2C12 skeletal muscle cells --- p.32 / Chapter 2.3.2 --- Protein quantitation --- p.33 / Chapter 2.3.3 --- 2D Gel electrophoresis --- p.34 / Chapter 2.3.4 --- Image analysis --- p.36 / Chapter 2.3.5 --- In gel digestion and MALDI-ToF MS --- p.37 / Chapter 2.4 --- Mitochondrial purification and protein extraction --- p.38 / Chapter 2.4.1 --- Ultracentrifugation method --- p.38 / Chapter 2.4.2 --- Mitochondrial Isolation Kit --- p.39 / Chapter 2.5 --- Western Immunoblotting --- p.40 / Chapter 2.5.1 --- Protein sample preparation --- p.40 / Chapter 2.5.2 --- SDS-PAGE --- p.40 / Chapter 2.5.3 --- Western blotting --- p.40 / Chapter 2.5.4 --- Membrane Blocking and Antibody Incubations --- p.41 / Chapter 2.5.5 --- Detection of Proteins --- p.42 / Chapter 3 --- Results --- p.43 / Chapter 3.1 --- Differentiation of C2C12 myoblast into myotubes --- p.43 / Chapter 3.2 --- The effect of Palmitic acid on C2C12 Proliferation --- p.44 / Chapter 3.3 --- Comparison of total protein profiles of palmitic acid-treated C2C12 myotubes with control myotubes --- p.45 / Chapter 3.4 --- Western blotting of Akt and Phospho-Akt in C2C12 cells treated with Palmitic acid after acute exposure to insulin --- p.50 / Chapter 3.5 --- Comparison of two mitochondria isolation methodsultracentrifugation and mitochondrial isolation kit --- p.51 / Chapter 3.5.1 --- Quantity of extracted mitochondrial protein --- p.51 / Chapter 3.5.2 --- Purity of extracted mitochondrial protein --- p.52 / Chapter 3.6 --- Comparison of mitochondrial protein profiles between palmitic acid-treated and control C2C12 myotubes --- p.53 / Chapter 3.7 --- Western blotting of insulin receptor substrate-1 and its serine phosphorylation --- p.58 / Chapter 4 --- Discussion --- p.59 / Chapter 4.1 --- Investigation of anti-proliferating effect of Palmitic acid on C2C12 using MTT assay --- p.59 / Chapter 4.2 --- Comparison of total protein profiles of palmitic C2C12 myotubes with control myotubes --- p.60 / Chapter 4.3 --- Western blotting of insulin receptor substrate-1and its serine phosphorylation --- p.62 / Chapter 4.4 --- Western blotting of Akt and Phospho-Akt in C2C12 cells treated with Palmitic acid after acute exposure to insulin --- p.63 / Chapter 4.5 --- Comparison of mitochondrial protein profiles between palmitic acid-treated and control C2C12 myotubes --- p.65 / Chapter 4.6 --- Problems faced and future prospect --- p.68 / Chapter 5 --- References --- p.69

As the prevalence of atherosclerosis has risen to an alarming level throughout the world, this thesis investigated: (1) the effects of type 2 diabetes mellitus on the risk factors for atherosclerosis and the intima-media thickness (IMT) of the common carotid arteries (a surrogate marker for atherosclerosis), (2) the contribution of various risk factors to the IMT of the common carotid arteries and (3) the interrelationship between the risk factors. / Atherosclerosis is the process by which the inner lining of a large or medium artery is deposited with lipids, cellular waste and other substances. It reduces the vessel's elasticity, lumen size and blood flow. Atherosclerosis is the primary underlying mechanism leading to cardiovascular and cerebrovascular diseases, the second and third leading causes of death in Hong Kong. / Both traditional and emerging risk factors for atherosclerosis were studied: traditional risk factors include age, blood pressure, indices of glycaemia control (fasting glucose, insulin and haemoglobin-Alc), and fasting lipids, while the emerging risk factors include, abdominal fat volume (subcutaneous and visceral), inflammatory markers (interleukin-6 (IL-6), interleukin-8 (IL-8) and high sensitivity c-reactive protein (hsCRP)), adiponectin, stress hormones (24 hr urinary noradrenaline and adrenaline, and plasma cortisol), and occupational stress (measured by a effort-reward imbalance questionnaire). / Starting with 204 subjects recruited from three different studies, data from 84 normoglycaemic subjects, 23 patients with impaired glucose tolerance (IGT) and 77 patients with diabetes mellitus (DM) were included in the analysis. When the IMT of the common carotid arteries and various risk factors were compared between normoglycaemic, IGT and DM subjects: (1) the IMT of the common carotid arteries showed an increasing trend with the worsening of glycaemia control (normal<IGT<DM), (2) increased prevalence of hypertension, dyslipidaemia, and obesity were observed among DM patients, and (3) increased levels of inflammatory markers, reduced concentration of adiponectin (a anti-inflammatory substance), and increased plasma cortisol concentration were also found among DM subjects. As the studies were limited by sample size, only a few risk factors were found significantly related to the carotid IMT. Age was the only common risk factor which was found to be correlated to the IMT of both the normoglycaemic and the DM/IGT subjects. (Abstract shortened by UMI.) / Fok Siu Pong. / "June 2005." / Adviser: Lester A. H. Critchley. / Source: Dissertation Abstracts International, Volume: 67-01, Section: B, page: 0173. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (p. 200-228). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

近年來，腸促胰島素類藥物胰高血糖素樣肽－1受體（GLP-1R）激動劑（如liraglutide，exenatide）和二肽基肽酶-4（DPP-4）抑制劑（如sitagliptin，vildagliptin）在2型糖尿病治療中得到廣泛應用。然而，2型糖尿病患者中腸促胰島素效應嚴重受損。研究表明，2型糖尿病患者的腸促胰島素激素（GLP-1和GIP）分泌並不顯著降低，因此腸促胰島素效應受損主要是由於2型糖尿病患者中β細胞對腸促胰島素激素反應性降低。GIP在2型糖尿病患者中刺激胰島素分泌的功能幾乎完全消失。相比較，GLP-1刺激胰島素分泌功能在2型糖尿病患者中部分保留。2型糖尿病中腸促胰島素效應受損的具體機制目前仍不清楚。本論文主要從2型糖尿病患者的腸促胰島素效應受損的機理及對腸促胰島素類藥物療效的影響上進行相關研究。 / 我們較早的研究發現高血糖能降低胰島β細胞GLP-1R受體的表達，從而損傷胰島β細胞GLP-1R信號通路是2型糖尿中腸促胰島素受損的部分原因。由於高血脂和高血糖都是糖尿病的主要特徵，我進一步研究了高血脂對β細胞的腸促胰島素信號通路的影響。體外實驗表明，棕櫚酸能降低胰島β細胞中GLP-1R的表達，並且抑制了GLP-1刺激的cAMP產生及CREB的磷酸化；在β細胞中外源性表達GLP-1R能部分恢復棕櫚酸損傷的GLP-1刺激cAMP產生及CREB的磷酸化。此外，在db/db小鼠和HFD誘導的肥胖及糖尿病小鼠模型中，降脂藥bezafibrate和niacin 能顯著提高腸促胰島素類藥物sitagliptin 和exendin-4的降糖效果，並且伴隨著對胰島形態結構的改善以及增加胰島β細胞質量。 / 另一方面，2型糖尿病患者胰島β細胞的功能和品質持續性的減少。其中慢性的高血糖和高血脂是兩個主要因素。臨床研究發現sitagliptin的降糖效果隨著糖尿病持續的時間增加而降低，而具體機理並不清楚。我們以前研究發現高血糖損傷胰島β細胞GLP-1R的表達及其信號通路是2型糖尿病腸促胰島素效應受損的重要原因。我進一步探討了exendin-4在STZ-HFD 誘導的較輕程度糖尿病（MH）小鼠（相對較輕的高血糖以及β細胞質量減少）和重度糖尿病(SH)小鼠（嚴重高血糖以及β細胞質量減少）的治療效果。研究發現， exendin-4只在MH小鼠中顯著降低血糖，改善糖耐量，恢復正常胰島結構及增加β細胞質量。而在兩組小鼠中exendin-4 都能降低體重，增加胰腺重量，但對食都沒影響。儘管exendin-4能顯著降低MH小鼠中胰島素耐量實驗葡萄糖水平，但HORM-IR無顯著差異。此外，exendin-4處理對胰島素刺激的肝臟及肌肉組織中磷酸化AKT和GSK水準在兩組小鼠中都無明顯改變。 / 總之，我的研究強調了血糖血脂的控制在2型糖尿病患者中的重要作用。我也發現高血糖、高血脂導致2型糖尿病患者β細胞功能持續受損的同時也損傷了GLP-1R信號通路，以至腸促胰島素類藥物療效的降低。我們的研究對腸促胰島素類藥物在2型糖尿病患者中的合理使用提供了重要資訊。 / Incretin-based drugs, such as glucagon-like peptide-1 (GLP-1) receptor agonists (e.g. liraglutide and exenatide) and dipeptidyl peptidase-4 (DPP-4) inhibitors (e.g. sitagliptin and vildagliptin), which inhibit degrading intact GLP-1, have been a novel therapeutics for the treatment of type 2 diabetes. Type 2 diabetes mellitus (T2DM) is associated with reduced incretin effects. The underlying mechanism, however, is not well understood. / Our previous studies showed that hyperglycemia downregulates glucagon-like peptide-1 (GLP-1) receptor (GLP-1R) which potentially contributes to the impaired incretin responses in cells. Whereas the effects of hyperlipidemia, another common clinical feature of T2DM, on GLP-1 response is largely unknown. In this study, I investigated the effects of free fatty acids (FFA) on incretin receptor signalings, and examined the glucose-lowering efficacy of incretin-based drugs in combination with lipid-lowering agents. I found that palmitate treatment decreased GLP-1R expression in rodent insulinoma cell lines, which was associated with impaired GLP-1 stimulated cAMP production and phosphorylation of CREB. Over-expression of GLP-1R restored the cAMP production and the phosphorylation of CREB. Treatment with bezafibrate or niacin in combination with des-fluoro-sitagliptin or exendin-4 produced more robust glycemic control associated with improved pancreatic islet morphology and islet cell function in db/db mice and HFD-fed mice. / On the other hand, chronic hyperglycemia and hyperlipidemia can cause a progressive deterioration in pancreatic beta-cell function and mass in patients with type 2 diabetes mellitus. It has been reported that the efficacy of incretin-based therapeutics is attenuated with the duration of diabetes. In our previous study, we have shown that hyperglycemia downregulates GLP-1 receptor which in turn may contribute to the impaired incretin effect in type 2 diabetes. In this study, I further investigated the efficacy of GLP-1 based drug exendin-4 in a rodent model of type 2 diabetes with different degrees of hyperglycemia and reduction of beta cell mass. I found that in moderate hyperglycemia (MH) group but not in severe hyperglycemia (SH) group, exendin-4 treatment significantly reduced fed glucose levels and plasma lipid profiles, improved glucose tolerance and glucose stimulated insulin secretion, and was associated with restored islets morphology and increased beta cell mass. Exendin-4 significantly decreased body weight gain and increased pancreatic mass both in MH and SH group. Although glucose levels were significantly reduced in MH group with exentin-4 treatment during insulin tolerance test, exendin-4 had no effects on HORM-IR, food intake, and insulin stimulated p-AKT/p-GSK in liver and muscle in both MH and SH group. / In summary, my findings highlight the importance of comprehensive lipid and glycemic control in type 2 diabetes mellitus. I found that factors including hyperglycemia and hyperlipidemia that cause progressive decline in beta cell failure impaired beta cell GLP-1R signaling as well as the efficacy of incretin-based therapies. These results add to our knowledge regarding the mechanism of incretin-based therapy in improving glycemic control in type 2 diabetic patients and provide new insights in designing treatment strategies including incretin-based therapy for type 2 diabetic patients. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Kang, Zhanfang. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 103-123). / Abstract also in Chinese. / 論文摘要 --- p.viii / Impaired Incretin Effects in Type 2 Diabetes: Mechanism and Therapeutic Implication --- p.1 / DECLARATION --- p.i / ACKNOWLEGEMENTS --- p.ii / ABBREVIATIONS --- p.iii / PUBLICATIONS AND AWARDS --- p.v / Chapter 1 --- Abstract --- p.vi / Chapter 2 --- Chapter : Introduction --- p.1 / Chapter 2.1 --- The history of incretin discovery --- p.1 / Chapter 2.2 --- The incretin hormones:GLP-1 and GIP --- p.1 / Chapter 2.3 --- Gene structure and regulation of incretin hormone gene expression --- p.2 / Chapter 2.3.1 --- Gene structure and regulation of GLP-1 gene expression --- p.2 / Chapter 2.3.2 --- Gene structure and regulation of GIP gene expression --- p.5 / Chapter 2.4 --- Secretion and metabolism of GLP-1 and GIP --- p.5 / Chapter 2.4.1 --- Regulation of GLP-1 and GIP secretion --- p.5 / Chapter 2.4.2 --- Degradation of GLP-1 and GIP by DPP-4 enzyme --- p.8 / Chapter 2.5 --- GLP-1 and GIP receptor --- p.10 / Chapter 2.6 --- biological actions of GLP-1 and GIP --- p.11 / Chapter 2.6.1 --- Actions of GLP-1 in peripheral tissues --- p.12 / Chapter 2.6.2 --- Actions of GIP in peripheral tissues --- p.17 / Chapter 2.7 --- Impaired incretin effect in type 2 diabetes patients --- p.17 / Chapter 2.7.1 --- Secretion of incretin hormones in patients with type 2 diabetes --- p.18 / Chapter 2.7.2 --- Impaired the responsiveness to GLP-1 and GIP in pancreatic beta cells --- p.19 / Chapter 2.8 --- Incretin-based drugs --- p.19 / Chapter 2.9 --- Type 2 diabetes and beta cell failure --- p.21 / Chapter 2.9.1 --- Natural history of type 2 diabetes --- p.21 / Chapter 2.9.2 --- Decline of beta cell function and mass in type 2 diabetes --- p.22 / Chapter 2.9.3 --- Factors for progressive loss of beta cell function and mass --- p.24 / Chapter 3 --- Chapter: Pharmacological reduction of free fatty acids restores the efficacy of incretin-based therapies in diabetic mouse models through beta cell GLP-1 receptor signalings --- p.30 / Chapter 3.1 --- Summary --- p.30 / Chapter 3.2 --- Introduction --- p.32 / Chapter 3.3 --- Materials and Methods --- p.35 / Chapter 3.3.1 --- Chemicals and Reagents --- p.35 / Chapter 3.3.2 --- Preparation of 8 mM sodium palmitate solution with 10.5% BSA --- p.35 / Chapter 3.3.3 --- Construct of an adenoviral vector for expressing mouse GLP-1R --- p.36 / Chapter 3.3.4 --- Cell culture and treatment --- p.37 / Chapter 3.3.5 --- RNA extraction and quantitative RT-PCR --- p.37 / Chapter 3.3.6 --- Analysis of phosphorylation of CREB --- p.38 / Chapter 3.3.7 --- Measurement of insulin secretion --- p.39 / Chapter 3.3.8 --- RT-PCR analysis of mouse GLP-1R expression --- p.39 / Chapter 3.3.9 --- Measurement of cAMP production --- p.40 / Chapter 3.3.10 --- Animals and experimental protocols --- p.40 / Chapter 3.3.11 --- Oral glucose tolerance test (OGTT) and insulin tolerance test (ITT) --- p.41 / Chapter 3.3.12 --- Acute glucose-lowering actions of Ex-4 and D-GIP in db/db Mice --- p.41 / Chapter 3.3.13 --- Lipid levels measurement --- p.42 / Chapter 3.3.14 --- Histological analysis --- p.42 / Chapter 3.3.15 --- Statistical analysis --- p.42 / Chapter 3.4 --- Results --- p.43 / Chapter 3.4.1 --- Reduced expression of GLP-1R in palmitate-treated b cells and islets of hyperlipedemic db/db mice. --- p.43 / Chapter 3.4.2 --- Palmitate impairs GLP-1 stimulated cAMP production and p-CREB in rodent insulinoma cell lines --- p.45 / Chapter 3.4.3 --- Palmitate reduced GLP-1 and GIP stimulated insulin secretion in rat INS-1E cells --- p.46 / Chapter 3.4.4 --- Mouse GLP-1R mRNA is expressed in rat INS-1E cells after infected with Ad-GLP-1R --- p.47 / Chapter 3.4.5 --- Expression of exogenous GLP-1R restores GLP-1 stimulated cAMP production and p-CREB in palmitate-treated rodent insulinoma cell lines --- p.48 / Chapter 3.4.6 --- Lipid lowering enhances the efficacy of DPP-4 inhibitor des-fluoro-sitagliptin in db/db mice --- p.50 / Chapter 3.4.7 --- Lipid-lowering enhances the efficacy of DPP-4 inhibitor des-flouro-sitagliptin in HFD-fed mice --- p.56 / Chapter 3.4.8 --- Lipid lowering enhances the efficacy of an agonist to GLP-1R (Ex-4) but not to GIPR (D-GIP) in db/db mice --- p.59 / Chapter 3.5 --- Discussion --- p.67 / Chapter 4 --- Chapter : Further study on the impairment of incretin effect by hyperglycemia in a rodent model of type 2 diabetes --- p.71 / Chapter 4.1 --- Summary --- p.71 / Chapter 4.2 --- Introduction --- p.73 / Chapter 4.3 --- Materials and Methods --- p.76 / Chapter 4.3.1 --- Animals and treatment --- p.76 / Chapter 4.3.2 --- Oral glucose tolerance test and insulin tolerance test --- p.76 / Chapter 4.3.3 --- Plasma parameters --- p.77 / Chapter 4.3.4 --- Histological staining and quantification of beta cell mass --- p.77 / Chapter 4.3.5 --- Insulin signaling analysis --- p.78 / Chapter 4.3.6 --- Western blot analysis --- p.78 / Chapter 4.3.7 --- Statistical analysis --- p.79 / Chapter 4.4 --- Results --- p.80 / Chapter 4.4.1 --- Exendin-4 reduced fed glucose levels in MH mice but not in SH mice --- p.80 / Chapter 4.4.2 --- Exendin-4 reduced body weight gain and did not affect food intake in both MH mice and SH mice --- p.81 / Chapter 4.4.3 --- Exendin-4 improved glucose tolerance and glucose stimulated insulin secretion in MH mice but not in SH mice --- p.83 / Chapter 4.4.4 --- Effects of exendin-4 on insulin sensitivity in MH and SH mice --- p.84 / Chapter 4.4.5 --- Effects of exendin-4 on lipid profiles in MH and SH mice --- p.86 / Chapter 4.4.6 --- Effects of exendin-4 on tissues weight in MH and SH mice --- p.87 / Chapter 4.4.7 --- Pancreatic islet morphology and analysis of beta cell mass --- p.88 / Chapter 4.4.8 --- Exendin-4 had no significant effects on insulin signaling pathway in liver and muscle --- p.91 / Chapter 4.5 --- Discussion --- p.94 / Chapter 5 --- Chapter : Summary --- p.100 / Chapter 6 --- References --- p.103

Este estudo, com delineamento tipo caso-controle, teve como proposta testar as hipóteses de que a amamentação ao seio é um fator de proteção para o DMID e o leite de vaca, introduzido precocemente na alimentação infantil, é um fator de risco para a doença. Os casos foram identificados na Associação de Diabetes Juvenil de São Paulo e no ambulatório de Endocrinologia da Escola Paulista de Medicina. Trezentos e quarenta e seis casos, com idade inferior a 18 anos no momento da entrevista, foram comparados com 346 controles pareados aos casos segundo sexo, idade e local de residência. Foram consideradas como variáveis de principal interesse a duração do aleitamento exclusivamente ao seio, a idade da introdução de alimentos lácteos na dieta e ter recebido leite em pó na maternidade. Foram consideradas como variáveis de controle as idades da mãe e do pai no momento do nascimento da criança, o histórico da mãe de rubéola congênita, a duração da gestação, o peso e o comprimento ao nascer, a situação de vacinação, os antecedentes relativos a doenças viróticas da criança, o histórico da criança de episódios graves de diarréia, a data da insulinoterapia, os antecedentes familiares de DMID e DMNID, a renda familiar per capita e a ordem de nascimento da criança. Utilizaram-se o teste t de Student pareado para a comparação das médias das variáveis cujos valores têm distribuição normal e o teste pareado dos sinais dos postos de Wilcoxon para as demais, a técnica de tábua de vida atuarial para se conhecer, aos 7 e aos 60 dias, a proporção de crianças ainda em aleitamento exclusivamente ao seio e sem introdução de alimentos lác- teos. O modelo de regressão logística condicional foi utilizado tanto para as análises da gradação dos odds ratios como para ajustar os efeitos sobre o DMID das três variáveis de interesse a possíveis variáveis de confusão. Os resultados encontrados neste estudo indicam que são fatores de risco para o DMID a ausência de aleitamento exclusivamente, especialmente durante a primeira semana de vida (OR = 2,13, IC: 1,28 - 3,55) e a idade da introdução de alimentos lácteos, especialmente quando esses alimentos são introduzidos durante os primeiros sete dias de vida (OR = 2,29; IC: 1,37 - 3,83). / This case-control study aimed to test the assumption that breast feeding protects against insulin-dependent diabetes mellitus, and that the early introduction of cow milk into the infant diet is a risk factor for the disease. The cases were identified in the Juvenile Diabetes Association of São Paulo, and in the Out-patients Endocrinology Department of the Escola Paulista de Medicina. Three hundred and forty-six cases among patients younger than eighteen years old at the time of the interview were compared with 346 paired control cases for sex, age and place of residence. The main variables were the duration of exclusive breast feeding , the age at which milk products were introduced into the diet, and whether powdered milk was given in the maternity unit. The ages of the parents when the child was born, history of congenital rubella in the mother, duration of gestation, weight and height at birth, vaccination status, the child\'s viral disease history, the child\'s history of severa attacks of diarrhea, the date of insulin therapy, previous familial history of insulin-dependent diabetes mellitus and non-insulin-dependent diabetes mellitus, the per-capita income of the family, and the order of birth of the child. Student\'s paired test was used to compare the mean values of variables with normal distribution, and Wilcoxon\'s signed ranks test was used for all other variables. The actuarial life table technique was used at 7 and 60 days in order to determine the proportion of children still being exclusively breast fed without the introduction of milk products. The conditional logistical regression method was used in dose-response analyses of the odds ratio and to adjust for the effect of the three variables of interest and possible confounding variables on insulin-dependent diabetes mellitus. The findings of this study indicate that the lack of exclusive breast feeding is a risk factor to insulin-dependent diabetes mellitus, particularly during the first week of life (OR=2.13; IC: 1.28-3.55) and that the age at introduction of milk products is a risk factor for the disease, particularly when these products are introduced during the first seven days of life (OR=2.29; IC: 1.37 -33.83).

Latinos are the fastest growing minority group in the Unites States (Fry, 2008). One in eight adult Latinos living in the United States has diabetes (CDC, 2011), and by the year 2020 diabetes is expected to increase by 107% in the Latino population (Caballero & Tenzer, 2007). Within the general diabetic population approximately 26% of the diabetic population requires the use of insulin in the management of their diabetes (DHHS: NDIC, 2011), making insulin-dependent diabetes a prevalent experience. The literature on how diabetes is experienced is divided. Clinical assessment literature strives to measure how people are coping with the illness and how one's experience with the disease impacts self-care. Literature on the diabetes experience is limited; however, the overall image that emerges is the negative expectation associated with having diabetes such as loss and suffering. Little is known about insulin-dependent diabetes as a lived experience, particularly among Latinos. The purpose of this research is to understand the experience of having insulin-dependent diabetes among adult Latinos, because focusing on this experience clarifies how daily nuances of living with the illness gives meaning to insulin-dependent diabetes. Increased understanding of how people interpret their illness can improve diabetes management, specifically within patient and social work interactions, and promote competent social work practice. The guiding research question for this research is, "what is the lived experience of insulin-dependent diabetes among Adult Latinos in a Primary Care Clinic in San Antonio?" This study uses van Manen's (1990) hermeneutic phenomenological approach to guide the research in capturing the nature of the phenomenon in order to gain a deeper understanding of the meaning Latinos attribute to daily experiences of having insulin-dependent diabetes. Utilizing a phenomenologically designed interview guide, this study includes interviews with 10 participants from a predominantly Latino, safety-net clinic in Texas with a 60% diabetes diagnosis rate. Five essential themes arose in exploring the lived experience of insulin-dependent diabetes among adult Latinos in a primary clinic in San Antonio. The themes include 1. diabetes goes against the natural state of the human body; 2. diabetes rules everything 3. insulin is the fast track to deterioration; 4. the relationships don't end, but they're not the same; and 5. managing diabetes with a broken system. The theme "diabetes goes against the natural state of the human body" is considered a core theme because it represents the other themes. Of those themes identified three support the current literature found on living with diabetes. The three themes insulin is the fast track to deterioration, managing diabetes with a broken system, and the subtheme love hate relationship with food are emerging themes identified by the study

The aim of this study was to document and explore the perceived role of nurses and their attitudes and beliefs when providing health promotion strategies and health education for hospitalised people who have diabetes mellitus (diabetes). As part of the exploratory, descriptive study key steps undertaken included : 1/. Determining the strategies the nurses currently use to provide health promotion and health education to patients; 2/. Documenting of the role nurses play in referring people to diabetes educators; 3/. and 3/. Determining the extent to which nurses feel able to fulfil the roles of health promotion and health education. The study reported in this thesis was conducted in Western Sydney within a socially, culturally and economically diverse population. Study participants were nurses working in medical or surgical wards. The study reveals that nurses require support from all levels of the healthcare system. Additionally, all levels of the healthcare system need to work together to investigate, implement and evaluate new models of care that are responsive to the dynamic state of the contemporary health care systems. / Master of Nursing (Hons)

Globally the diabetes epidemic is a major health challenge. Associated with the diagnosis of diabetes is the morbidity and premature mortality stemming from the complications of the disease. It was identified that approximately 50% of clients who attended a diabetes centre in an outer western metropolitan region of Sydney were not completing diabetes education. A strategy employed to overcome this was the introduction of a 2 ½ hour group diabetes education program called the Ongoing Education System (OES), for persons with Type 2 diabetes, that enabled completion of education at this one session. However, debate occurred among health professionals at the Wentworth Diabetes Service (WDS) as to the effectiveness of the OES as compared to the traditional individual education sessions. (one-on-one education). The purpose of this study was to compare the outcomes of two modes of diabetes education for completing education for clients with Type 2 diabetes , namely individual education (Treatment A) and the OES group education (Treatment B). The findings overall revealed no difference in the outcomes of participants who received individual education and those who received the OES at completion of education as well as at 6 and 12 month post education. A secondary finding of this study was the significant influence gender and age exerted on the outcomes of the education programs. One significant implication from the findings for both the person diagnosed with Type 2 diabetes and the health care organisation is that the OES provides a cost effective alternative to individual education that encourages clients to complete diabetes education thereby enabling the person to achieve an optimal quality of life. In addition this study provides research evidence for the benefit of current practice in diabetes education. / Doctor of Philosophy (PhD)

Peptide YY (PYY) is a gut-derived hormone that is renowned for its effects on satiety. Reduced satiety in obese people has been attributed to low fasting and postprandial PYY levels. However, it has not been determined whether low PYY levels are the cause or the outcome of obesity. Moreover, the long-term role of PYY in regulating energy balance is unclear. Results presented in this thesis, using PYY-deficient mice (PYY-/-) and PYY transgenic mice (PYYtg) highlight that PYY indeed has an important role in regulating energy balance and glucose homeostasis in vivo. PYY knockout mice became obese with ageing or high-fat feeding linked to a hyperinsulinemic phenotype associated with hypersecretion of insulin from isolated pancreatic islets. These findings suggested that PYY deficiency may be a predisposing factor for the development of obesity and type 2 diabetes. On the other hand, PYYtg mice exhibited decreased adiposity and increased metabolism under high-fat feeding. Furthermore, PYYtg/ob mice had improved glucose tolerance and decreased adiposity. These latter studies suggested that high circulating PYY levels may protect against the development of obesity and type 2 diabetes. Interestingly, both animal models support PYY as an important regulator of the somatotropic axis. These preliminary findings prompted investigations in understanding whether low PYY levels may be a predisposing factor for the development of obesity and type 2 diabetes in human subjects. In a population of healthy human subjects that had a predisposition to the development of type 2 diabetes and obesity, fasting PYY levels were lower than in normal subjects. Moreover, low fasting PYY levels strongly correlated with decreased insulin sensitivity and high levels of fasting insulin. Collectively, these findings suggest that low circulating levels of PYY could contribute to increased adiposity, insulin resistance and type 2 diabetes. Therefore determination of PYY levels may be a method of detecting whether people are predisposed to becoming obese and insulin resistant. This work also suggests that treatments that enhance circulating PYY levels may be protective in the development of obesity and type 2 diabetes.