The ability of insulin to stimulate glucose uptake into muscle and adipose tissue is central to the maintenance of whole-body glucose homeostasis. Deregulation of insulin action manifests itself as insulin resistance, a key component of type 2 diabetes. Insulin resistance is also observed in HIV patients receiving protease inhibitors. An agent that can reversibly induce an insulin-resistant state would be a very useful tool in developing model systems that mimic the pathogenesis of type 2 diabetes. Insulin resistance can arise from defects in insulin signal transduction, changes in the expression of proteins or genes that are targets of insulin action, cross talk from other hormonal systems or metabolic abnormalities. Deterioration of the insulin-receptor-signalling pathway at different levels leading to decreased levels of signalling pathway intermediates and/or decreased activation through phosphorylation accounts for the evolution from an insulin-resistant state to type 2 diabetes. In addition, defects in GLUT4 glucose transporter translocation are observed, further fuelling impairments in skeletal muscle glucose uptake. Levels of insulin-induced GLUT4 translocation in the skeletal muscle of type 2 diabetic patients are typically reduced by 90%. Many cellular pathways & their intermediates are in some way or another linked to insulin signalling. This study focused on three of these namely the PI3-kinase/Akt pathway, the Mitogen Activated Protein Kinase (MAPK) cascade and the AMP Kinase pathway, with successful monitoring of the PI3-K pathway. Investigations involved observing and evaluating the effects of various compounds as well as an indigenous medicinal plant, Sutherlandia frutescens on the activities of key insulin signalling pathway intermediates within the three fore mentioned pathways including Akt, AMPK and MEK1/2 as well as membrane surface GLUT4 levels. Scientific research has in the past leant heavily on Western blotting as the method of choice for gaining vital information relating to signal transduction pathways, however for research into cellular mechanisms the negatives of this method outweigh the positives. The drawbacks include a need for large amount of cells, multiple washing steps which may be disadvantageous to any weak and transient interactions as well as lysing of cells which may interfere with the maintenance of the subcellular localisation of a specific signalling event. Based on these, the need for a better method in terms of speed & reliability to monitor phosphorylation states of signal transduction pathway intermediates & GLUT4 translocation was evident and was one VII of the main aims & successes of this study. The method created used the mouse muscle cell line C2C12 in conjunction with the quick, sensitive method of flow cytometry which allowed us to monitor these processes in these cells through immune-labelling. Adherent cell cultures such as the C2C12 cell line pose the problem of possible damage to plasma membrane receptors (including insulin receptors) during harvesting to obtain a cell suspension for flow cytometry. We however used C2C12 mouse myocytes to optimize a method yielding insulin responsive cells in suspension that were successfully used for flow cytometry after immunelabelling of insulin signalling intermediates. Insulin (0.1μM) significantly raised the levels of both P-Akt and GLUT4 above basal levels. This effect was shown to be dose dependent. At a concentration of 50μg/ml, Sutherlandia frutescens was able to act as an insulin-mimetic in terms of its ability to increase P-Akt levels, GLUT4 translocation and glucose utilisation in an acute manner. These increases could be reduced with the addition of wortmannin, a PI3-K inhibitor. Therefore, these results suggest the mechanism of the plant extract’s insulin-like activity may be in part due to the activation of the insulin signalling pathway leading to GLUT4 translocation, which involves the phosphorylation of insulin receptor- and subsequent PI3-K activity, leading to P-Akt activity. These results provide further evidence of this plant extract’s anti-diabetic potential. The effect of Sutherlandia frutescens on insulin secretion, calcium signalling and proliferation in INS-1 rat pancreatic cells was also investigated and it was found to increase the activities of all of these processes. However no change in the levels of GLUT2 glucose transporter was seen. Ritonavir is prescribed by the South African Department of Health in co-formulation with other protease inhibitors within its second regime in the treatment of HIV and AIDS. Using C2C12 cells, ritonavir decreased glucose uptake acutely and had no effect on GLUT4 translocation however surprisingly increased P-Akt levels. In conclusion, it was found that Sutherlandia frutescens has antidiabetic benefits, diverse in nature depending on tissue type as well as length of time administered. The establishment of novel flow cytometry techniques to assess antidiabetic properties using in vitro cell culture was achieved. These methods will be useful in the future for the assessment of insulin sensitivity and in the identification of novel compounds that stimulate the insulin signalling pathways.

Health coaching is a promising approach to support self-management of chronic conditions like type 2 diabetes; however, there aren’t enough coaching practitioners to support those in need. Advances in Artificial Intelligence (AI) and Machine Learning (ML) have the potential to enable innovative, automated health coaching interventions, but important gaps remain in applying AI and ML to coaching interventions. This thesis aims to identify computational approaches and interactive technologies that enable automated health coaching systems. First, I utilized computational approaches that leverage individuals’ self-tracking and health data and used an expert system to translate ML inferences into personalized nutrition goal recommendations. The system, GlucoGoalie, was evaluated in multiple studies including a 4-week deployment study which demonstrated the feasibility of the approach. Second, I compared human-powered and automated/chatbot approaches to health coaching in a 3-week study which found that t2.coach — a scripted, theoretically-grounded chatbot designed through an iterative, user-centered process — cultivated a coach-like experience that had many similarities to the experience of messaging with actual health coaches, and outlined directions for automated, conversational coaching interventions. Third, I examined multiple AI approaches to enable micro-coaching dialogs — brief coaching conversations related to specific meals, to support achievement of nutrition goals — including a knowledge-based system for natural language understanding, and a data-driven, reinforcement learning approach for dialog management. Together, the results of these studies contribute methods and insights that take steps towards more intelligent conversational coaching systems, with resonance to research in informatics, human-computer interaction, and health coaching.

The pathophysiology of cytokines released by infiltrating white blood cells upon pancreatic beta cells is not fully understood. Early growth response gene-1 (Egr-1) expression is specifically and transiently up regulated in pancreatic beta cells in response to glucose. We hypothesized that interleukin-1 beta (IL-1▀) induction of nitric oxide alters glucose induced Egr-1 transcription levels. Egr-1 levels were assessed via western blot, nitric oxide was measured with a Griess Reagent kit and insulin levels via ELISA. Glucose induced both insulin and Egr-1 production in INS-1 cells. IL-1▀ dose dependently increased nitric oxide production over time and significantly attenuated glucose induced Egr-1 expression. Sodium nitroprusside dose dependently reduced glucose induced Egr-1 production. The data suggest a strong relationship between IL-1▀ induced nitric oxide production and the reduction of glucose stimulated Egr-1 production. The pathways altered by this cytokine could provide a better understanding of the pathophysiology leading to pancreatic beta cell death.

PrediXcan, an imputed gene expression-trait association method, was compared to multiple linear regressions (MLR) of single nucleotide polymorphisms (SNPs) using the quantitative phenotypes serum total cholesterol (TC), low-density lipoprotein cholesterol (LDL), high-density lipoprotein cholesterol (HDL) and triglycerides (TG). The gene expression prediction models were trained using transcriptome- and genome-wide data from Depression Genes and Networks (DGN whole blood) and Genotype-Tissue Expression (GTEx) Project (GTEx whole blood, GTEx pancreas and GTEx liver). Linear combinations of the effect sizes derived using elastic net or least absolute shrinkage and selection operator (LASSO) with genotypes from 1304 European patients from the Diabetes Control and Complications Trial (DCCT) were used to estimate the genetically regulated expression (GReX) for genes. Different gene expression predictors were present in each training set. The 10-fold cross-validated predictive performance, estimated GReX, and p values from associations for matched genes were weakly correlated across training sets and strongly correlated for models derived using elastic net and LASSO. MLR models had more significant associations than PrediXcan models and larger inflation factors for p values. A comparison of p values for matched genes between PrediXcan and MLR models showed weak correlations but strong evidence for LDL and HDL associations with genes at locus 1p13.3 and 16q13, respectively. / Thesis / Master of Science (MSc)

Objective: To identify whether perceived stress is a risk-factor for higher cortisol levels and greater insulin resistance in Type 2 diabetic patients, using data from participants with and without diabetes in the National Survey of Midlife Development in the United States (MIDUS), specifically MIDUS II, Project 4. The following hypotheses were tested: (H1a) greater perceived stress would be associated with higher cortisol for Type 2 diabetic participants, (H1b) the perceived stress/cortisol relationship would be stronger for people with Type 2 diabetes than for those without it, (H2) greater perceived stress would be associated with higher Homeostatic Model Assessment-Insulin Resistance (HOMA-IR, insulin-resistance) for Type 2 diabetic participants, (H3a) subjective well-being would moderate the perceived stress/insulin resistance relationship for Type 2 diabetic participants, and (H3b) depression would moderate the perceived stress/insulin resistance relationship for Type 2 diabetic participants. Method: MIDUS, a longitudinal study of over 7,000 American adults, explores biopsychosocial factors that could contribute to variance in mental/physical health. Only complete data were utilized. Type 2 participants (n=115) consisted of 54 males and 62 females ranging in age from 36 to 81 years. Non-diabetic participants (n=1097) consisted of 470 males and 627 females ranging in age from 34 to 84 years. Results: None of the predicted relationships were statistically significant. Waist to hip ratio was significantly related to insulin resistance (r = .31, p = .001). Conclusions: Future studies should collect information about the type and duration of stressors in addition to perceptions about stress for those with Type 2 diabetes.

Dados prévios ja demostram que o controle intensivo da glicemia diminui o risco de eventos microvasculares em pacientes com diabetes mellitus. No entanto, seu efeito cardiovascular é incerto. Nós sumarizamos os dados de estudos das principais bases de dados. 2 revisores extraíram dados de estudos randomizados de pacientes com diabetes tipo 2, que visavam 2 níveis de intensidade da glicemia. Investigou-se as retinopatia, neuropatias, nefropatias, mortalidade cardiocascular e total, infarto do miocárdio (IAM), acidente vascular cerebral, amputação de membros e episódios de hipoglicemia. Realizamos a meta-análise para obter o risco relativo (RR). Foram incluídos 7 estudos com 27.814 pacientes. O controle intensivo reduziu o RR de IAM e amputação, além progressão da retinopatia, incidência de neuropatia periférica, incidência e progressão de nefropatia e microalbuminúria. Entretanto, dobrou o risco de episódios de hipoglicemia. Não houve diferenças quanto à mortalidade e outros resultados. Conclui-se que controle intensivo reduziu o risco de alguns eventos, sem reduzir a mortalidade, porém as custas do dobro da incidência de de hipoglicemia. / Previous data already show that intensive glucose control reduces the risk of microvascular events in patients with diabetes mellitus. However, its cardiovascular effect is uncertain. We summarize data from studies of the major databases. 2 reviewers extracted data from randomized studies of patients with type 2 diabetes, aimed at two intensity levels of blood glucose. We investigated the retinopathy, neuropathy, nephropathy, and total mortality cardiocascular, myocardial infarction (IAM), stroke, limb amputation and episodes of hypoglycemia. We conducted a meta-analysis to obtain the relative risk (RR). We included seven studies with 27.814 patients. The intensive control reduced the RR of IAM, and amputation, and progression of retinopathy, incidence of peripheral neuropathy, incidence and progression of nephropathy and microalbuminuria. However, it doubled the risk of hypoglycemia. There were no differences in mortality and other outcomes. We conclude that intensive control reduced the risk of some events without reducing mortality, but the expense of twice the incidence of hypoglycemia.

Fan, Rongrong. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 130-150). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Kwan, Yee Mei. / Thesis (D.Nurs.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 152-171). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese; appendixes includes Chinese.

Cheng, Suosuo. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 159-173). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts aslo in English.

Poon, Chui Wa Christina. / "August 2011." / Thesis (M.Phil.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 123-131). / Abstracts in English and Chinese. / ABSTRACT --- p.i / 論文摘要 --- p.vi / ACKNOWLEDGEMENTS --- p.ix / PUBLICATIONS --- p.x / Abstracts --- p.x / ABBREVIATIONS --- p.xii / Chapter 1. --- GENERAL INTRODUCTION --- p.1 / Chapter 1.1. --- Diabetes --- p.1 / Chapter 1.1.1. --- Overview --- p.1 / Chapter 1.1.2. --- Diagnostic Criteria of Type-2 Diabetes --- p.2 / Chapter 1.1.3. --- Type-2 Diabetes (T2DM) --- p.3 / Chapter 1.1.3.1. --- Impaired Insulin Synthesis and Insulin Secretory Defects in Type-2 Diabetes --- p.3 / Chapter 1.1.3.2. --- β-Cell Dysfunction --- p.5 / Chapter 1.1.3.3. --- Insulin Resistance --- p.5 / Chapter 1.1.4. --- Glucose Toxicity --- p.6 / Chapter 1.1.4.1. --- Fasting Hyperglycemia --- p.8 / Chapter 1.1.4.2. --- Postprandial Hyperglycemia --- p.8 / Chapter 1.2. --- Oxidative Stress --- p.8 / Chapter 1.2.1. --- ROS and Mitochondria --- p.8 / Chapter 1.2.2. --- ROS Production by Mitochondria --- p.9 / Chapter 1.2.3. --- The Relationship of Glucose Recognition by β-cells and Oxidative Stress --- p.11 / Chapter 1.2.4. --- Important Roles of Glutathione in Pancreatic β-cells and Glutathione Synthesis --- p.14 / Chapter 1.2.5. --- N-acetyl-L-cysteine - A Potential Drug Treatment for Type-2 Diabetes? --- p.17 / Chapter 1.3. --- Role of F-actin Cytoskeleton on Glucose-induced Insulin Secretion --- p.18 / Chapter 1.4. --- Current Clinical Treatments for Type-2 Diabetes Mellitus --- p.21 / Chapter 1.4.1. --- Metformin --- p.22 / Chapter 1.4.2. --- Sulfonylureas --- p.22 / Chapter 1.4.3. --- Thiazolidinediones --- p.23 / Chapter 1.4.4. --- Glinides (Meglitinide Analogues) --- p.23 / Chapter 1.4.5. --- α-Glucosidase (AG) Inhibitors --- p.24 / Chapter 1.4.6. --- Dipeptidyl Peptidase-4 (DPP-4) Inhibitors --- p.24 / Chapter 1.4.7. --- (Clinical) Antioxidant Treatment --- p.24 / Chapter 1.5. --- Animal Models Used in Type-2 Diabetes Research --- p.25 / Chapter 1.6. --- Aims of Study --- p.27 / Chapter 2. --- RESEARCH DESIGN & METHODS --- p.28 / Chapter 2.1. --- Materials --- p.28 / Table 1. Sources and concentrations of drugs tested in this study: --- p.28 / Culture Medium - --- p.29 / General Reagents --- p.29 / Chapter 2.2. --- Isolation of Islets of Langerhans and Single Pancreatic β-Cells --- p.31 / Chapter 2.3. --- Measurement of Mitochondrial ROS Levels --- p.32 / Chapter 2.4. --- Measurement of Islets Insulin Release and Insulin Content --- p.34 / Chapter 2.4.1. --- Preparation of Samples --- p.34 / Chapter 2.4.2. --- Enzyme-Link Immunosorbent Assay (ELISA) --- p.35 / Chapter 2.5. --- Immunocytochemistry --- p.35 / Chapter 2.6. --- Data and Statistical Analysis --- p.37 / Chapter 3. --- RESULTS --- p.38 / Chapter 3.1. --- "Effects of L-NAC, Various Oxidative Stress Inducers/Reducers and Actin Polymerisation/Depolymerisation Inducers on Releasable Insulin Levels and Insulin Contents in Response to Low Glucose (5 mM) and High Glucose (15 mM) of Isolated Pancreatic Islets of (db+/m+) and (db+/db+) Mice" --- p.38 / Chapter 3.1.1. --- Effect of L-NAC on Insulin Secretion and Insulin Contents --- p.38 / Chapter 3.1.2. --- Effect of Cytochalasin B on Insulin Secretion and Insulin Contents --- p.39 / Chapter 3.1.3. --- Effect of 4-Phenyl Butyric Acid on Insulin Secretion and Insulin Contents --- p.43 / Chapter 3.1.4. --- Effect of Ursodeoxycholic Acid on Insulin Secretion and Insulin Contents --- p.46 / Chapter 3.1.5. --- Effect of Hydrogen Peroxide on Insulin Secretion and Insulin Contents --- p.49 / Chapter 3.1.6. --- Effect of Jasplakinolide on Insulin Secretion and Insulin Contents --- p.53 / Chapter 3.1.7. --- Effect of Thapsigargin on Insulin Secretion and Insulin Contents --- p.57 / Chapter 3.1.8. --- Effect of BSO on Insulin Secretion and Insulin Contents --- p.61 / Chapter 3.2. --- "Effects of L-NAC, Various Oxidative Stress Inducers/Reducers and Actin Polymerisation/Depolymerisation Inducers on Mitochondrial ROS Levels in Response to High Glucose (15 mM) Challenge in Isolated Single Pancreatic β-Cells of (db +/m+) and (db +/db +) Mice" --- p.65 / Chapter 3.2.1. --- "Effects of L-NAC (20 mM), 4-Phenyl Butyric Acid (4-PBA) (1 mM), Ursodeoxycholic Acid (UA) (500 μg/ml), H202 (200 μM), Thapsigargin (0.5 μM) and DL-Buthionine-[S,R]-Sulfoximine (BSO) (0.1 μM) Pre-treatments on Mitochondrial ROS Level in Response to High Glucose (15 mM) Challenge" --- p.65 / Chapter 3.2.2. --- "Effects of L-NAC (20 mM), Cytochalasin B (10 μM) and Jasplakinolide (5 μM) Pre-treatments on Mitochondrial ROS Level in Response to High Glucose (15 mM) Challenge_" --- p.76 / Chapter 3.3. --- "Effects of L-NAC, Various Oxidative Stress Inducers/Reducers and Actin Polymerisation/Depolymerisation Inducers on F-actin Cytoskeleton Levels Incubated in Low Glucose (5 mM) and High Glucose (15 mM) Medium in Single Pancreatic β-Cells of Non-Diabetic (db +/m+) and Diabetic (db +/db +) Mice" --- p.81 / Chapter 4. --- DISCUSSION --- p.100 / Chapter 4.1. --- General Discussion --- p.100 / Chapter 5. --- SUMMARY --- p.120 / Chapter 6. --- FUTURE PERSPECTIVES --- p.121 / Chapter 7. --- REFERENCES --- p.123