Vascular dysfunction is linked with increased free radical generation and is a major contributor to the high mortality rates observed in diabetes. Several probable sources of free radical generation have been suggested in diabetes, including cytochrome P450 (CYP) monooxygenase-dependent pathways. CYP-mediated superoxide production reduces nitric oxide (NO) bioavailability. In this study, we focus on the contribution of CYP monooxygenase enzyme-generated reactive oxygen species in vascular dysfunction in an experimental model of type II diabetes mellitus. The purpose of this study is to test the hypothesis that sulfaphenazole treatment can restore diabetic endothelial function in db/db mice. Diabetic male mice (db/db strain) and their age-matched controls received daily intraperitoneal injections of either the CYP 2C inhibitor sulfaphenazole (5 mg/kg) or saline (vehicle control) for 8 weeks. Fasting plasma glucose levels were measured before starting, during, and after finishing the treatment. As well, plasma levels of 8-isoprostane (as a marker of oxidative stress) and nitrite levels of aortic tissue (as a marker of NO bioavailability) were determined. Although sulfaphenazole did not change endothelium-dependent vasodilation in WT mice, it restored endothelial-mediated relaxation in treated db/db mice. We concluded that CYP 2C inhibition by sulfaphenazole reduces oxidative stress (measured as plasma levels of 8-isoprostane), increases NO bioavailability (measured as NOj) and restores endothelial function in db/db mice without affecting plasma glucose levels. Based on our findings, we speculate that inhibition of free radical generating CYP monooxygenase enzymes restores endothelium-dependent vasodilation induced by acetylcholine. In addition, it reduces oxidative stress and increases NO bioavailability.

Diabetes Mellitus is a common chronic disease that is an ever-increasing public health issue. Continuous glucose monitoring has been shown to help diabetes mellitus patients stabilize their glucose levels, leading to improved patient health. Hence, a glucose sensor, capable of continuous real-time monitoring, has been a topic of research for three decades. Current methods of glucose monitoring, however, require taking blood samples several times a day, hence patient compliance is an issue. Optical methods are one of the painless and promising methods that can be used for blood glucose predictions. However, having accuracies lower than what is acceptable clinically has been a major concern. To improve on the accuracy of the predictions, the signal-to-noise ratio in the spectrum can be increased, for which the use of thermally tunable vertical cavity surface emitting lasers (VCSELs) as the light source to obtain blood absorption spectra, along with a multivariate technique (Partial Least Square (PLS) techniques) for analysis, is proposed. VCSELs are semiconductor lasers with small dimensions and low power consumption, which makes them suitable for implants. VCSELs provide higher signal-to-noise ratio as they have high power spectral density and operate within a small spectrum. In the current research, experiments were run for the preliminary investigations to demonstrate the feasibility of the proposed technique for glucose monitoring. This research involves preliminary investigations for developing a novel optical system for accurate measurement of glucose concentration. Experiments in aqueous glucose solutions were designed to demonstrate the feasibility of the proposed technique for glucose monitoring. In addition, multivariate techniques, such as PLS, were customized for various specific purposes of this project and its preliminary investigation. This research will lead to the development of a small, low power, implantable optical sensor for diabetes patients, which will be a major breakthrough in the area of treating diabetes patients, upon successful completion of this research and development of the device.

The whole body UCP2 knockout (UCP2−/−) have enhanced insulin secretion and higher ATP content. However, these changes could be due to indirect effects of extra-pancreatic deletion and therefore, generating beta-cell specific knockout mice (UCP2BKO) is essential. A 90% knockdown of UCP2 protein was observed in beta-cells of UCP2BKO mice. No significant differences were observed in body weight accumulation, fasting blood glucose, plasma insulin or glucagon. UCP2BKO had impaired oral glucose tolerance with no differences in insulin secretion or sensitivity. Enhanced ROS accumulation was observed in the beta-cells of UCP2BKO and upregulation of antioxidant enzyme genes. Morphometric analysis showed an increased glucagon positive area in the pancreata of UCP2BKO mice. Results obtained from UCP2BKO were contrary to the phenotype observed in UCP2−/− mice. Overall, the characterization of UCP2BKO demonstrates that UCP2 in the beta-cell is involved in modulating ROS production.

The whole body UCP2 knockout (UCP2−/−) have enhanced insulin secretion and higher ATP content. However, these changes could be due to indirect effects of extra-pancreatic deletion and therefore, generating beta-cell specific knockout mice (UCP2BKO) is essential. A 90% knockdown of UCP2 protein was observed in beta-cells of UCP2BKO mice. No significant differences were observed in body weight accumulation, fasting blood glucose, plasma insulin or glucagon. UCP2BKO had impaired oral glucose tolerance with no differences in insulin secretion or sensitivity. Enhanced ROS accumulation was observed in the beta-cells of UCP2BKO and upregulation of antioxidant enzyme genes. Morphometric analysis showed an increased glucagon positive area in the pancreata of UCP2BKO mice. Results obtained from UCP2BKO were contrary to the phenotype observed in UCP2−/− mice. Overall, the characterization of UCP2BKO demonstrates that UCP2 in the beta-cell is involved in modulating ROS production.

Bakgrund: Diabetes typ två är en sjukdom som förebyggs och behandlas med bland annat livsstilsförändringar. Det är ett aktuellt ämne då diabetes typ två blir allt vanligare i Sverige och världen. Det uppskattas att 85-90 procent av alla som har diabetes i Sverige har diabetes typ två. Syftet med denna systematiska litteraturstudie var att belysa hur patienter upplever att drabbas av diabetes typ två med inriktning mot livsstilsförändringar. Metod: Åtta kvalitativa artiklar kvalitetsgranskades och ingår i studien. Analysen gjordes genom fyra frågeställningar som besvarade syftet. Resultatet presenterades under tre rubriker: Synen på sjukdomen, Inställningar till att göra livsstilsförändringar samt En ny identitet. Att drabbas av diabetes typ två innebar att patienterna förlorade sin tidigare identitet. Kroppen tog en ny plats och krävde nya behov. Genom att förneka sin sjukdom gick det att fortsätta leva sitt vanliga liv. Kunskap gav många gånger motsägelsefulla känslor. Att patienten fick bevara sin självständighet och ta kontroll över sin egen situation var av stor vikt. Att ändra en livsstilsförändring i taget upplevdes som hanterbart. Slutsatsen var att alla patienter har sin egen syn på sjukdomen och vårdaren måste ta hänsyn till den enskilda patientens livsvärld för att stärka och stödja patientens motivation till livsstilsförändring.

Proghrelin produces three proghrelin derived peptides (PGDP) known for their roles in glucose homeostasis: acylated ghrelin (AG), unacylated ghrelin (UAG), and obestatin (Ob). Only the receptor for AG, growth hormone secretagogue receptor 1a (GHS R1a), is known, however there is evidence for additional receptors for AG, UAG and Ob. Our aim was to determine the actions of PGDP on two beta cell lines, MIN6 and INS-1, which we have shown to contain and lack GHS R1a respectively. PGDP increased proliferation in INS-1 but not MIN6 cells, measured by BrdU incorporation. AG decreased apopotosis in both cell lines, measured by decreased levels of activated caspase 3. Insulin secretion was investigated in INS-1 cells, where PGDP modulated insulin release in a glucose dependent manner. Our results indicate that PGDP modulate beta cell mass in the presence and absence of GHS R1a, and present a detailed anaylsis of insulin secretion in INS-1 cells.

Diabetes Care Program of Nova Scotia (DCPNS) Registry data were used to examine factors associated with survival for clinically confirmed diabetes mellitus (DM) cases. Type 1 (N=2,043) and type 2 (N=47,974) cases were followed from first Diabetes Centre visit until death/study end. Kaplan Meier curves and Cox proportional hazard models were used to explore differences in survival by sex, district health authority of care, and comorbidity status (hypertension and/or dyslipidemia). Median lifespan for type 1 cases was 12 years shorter than for type 2 cases. Hazard rate ratios for those with dyslipidemia, hypertension, or both compared to those with neither comorbidity were 1.63, 2.57, and 7.52 for type 1 cases and 0.95, 1.15, and 1.00 for type 2 cases. Disease progression and the relationship between comorbidity status and survival differed markedly for the type 1 and type 2 DM populations underscoring the need to examine these populations separately.

The incidence of obesity, and the associated morbidities and mortality are increasing. Strategies to manage this disease hinge on the balance of caloric intake and energy expenditure. This regulation depends largely on endocrine input from the periphery. The recently discovered stomach derived hormone, ghrelin, has emerged as a key player in the regulation of appetite and energy storage. Ghrelin achieves these functions through binding the ghrelin receptor in appetite regulating neurons and in peripheral metabolic organs including the pancreas and adipose tissue. Since ghrelin acts on energy regulating metabolic organs, its secretion from the stomach is tightly coupled to energy availability. Ghrelin levels increase during periods of fasting and decrease after a meal is consumed. Under chronic energy surplus (such as obesity) ghrelin levels decrease while in chronic energy deficit (anorexia nervosa, weight loss) ghrelin levels increase. While major advances have been made in understanding both the function of ghrelin and its dysregulation in disease, little is known about the cellular regulation of ghrelin secretion. This is due to the lack of cellular models of ghrelin secretion. In this thesis, I describe the development of a novel ghrelin secreting primary rat stomach cell culture. Using this system I elucidated the roles and mechanisms of neurotransmitters, hormones (insulin and glucagon), nutrients (glucose) and anti-diabetics (metformin) in the regulation of ghrelin secretion. These findings have clearly demonstrated the ability of ghrelin cells to sense energy availability and provide important insights for ghrelin altering therapies. To evaluate both the function of ghrelin and the feasibility of reducing circulating ghrelin, I developed a novel in vivo ghrelin-reducing strategy. In vivo expression of a decoy protein based on the ligand binding domains of the ghrelin receptor was expressed in mice. Mice treated with this plasmid construct had reduced circulating levels of ghrelin. Interestingly, reduced circulating ghrelin was protective from high fat diet-induced obesity and resulted in improved glucose metabolism. This work demonstrates both the importance of ghrelin in peripheral energy storage and the feasibility of this novel ghrelin reducing approach for the treatment of obesity and insulin resistance.

Diabetic pregnant women have an increased risk of developing pre-eclampsia, a late gestational syndrome, although the reason for this gain is unknown. Placental pathology in pre-eclampsia is linked with insufficient spiral arterial modification, a process triggered by uterine natural killer (uNK) cells, an abundant pro-angiogenic cell type found in early pregnancy decidua (endometrium of the pregnant uterus). UNK cells effect spiral arterial modification, the blood supply to the placenta, through the release of interferon gamma (Ifng), a pro-inflammatory cytokine. Peripheral blood precursors of uNK cells employ a unique pattern of homing molecules to traffic to the decidua. The goal of this thesis was to advance the understanding of how homing and functions of uNK cell precursors might be modified in diabetic pregnancy. Studies employed both murine and human models. Pregnancies were studied microscopically in normoglycemic (n-) and hyperglycemic (d-) non-obese diabetic (NOD) and NOD.Ifng-/- (NOD strain with a genetic deletion of Ifng) mice. Pre-implantation embryo development was impaired in n- and d-NOD.Ifng-/- mice. Hyperglycemia decreased both numbers of uNK cells and spiral artery remodelling within d-NOD and d-NOD.Ifng-/- decidua. This decrease in spiral artery remodelling was independent of Ifng and linked with hypertrophy of smooth muscle in implantation sites. Blood leukocytes from control and diabetic pregnant women were evaluated for adhesive function and expression of key homing molecules. Diabetic leukocytes had decreased CD56+ (uNK cell lineage) cell adhesion to decidua, increased CD56+ cell adhesion to pancreas, and comparable adhesion to lymph node compared with control leukocytes, suggesting impaired decidual homing in vivo. Of 8 lymphocyte subsets resolved by flow cytometry, type 1 cytokine CD56bright cells expressed appropriate homing molecules most abundantly. Diabetes did not alter levels of expression of these receptors. These data show that diabetes alters the potential capacity for decidual homing of pre-uNK cells but that this is not achieved through reduction in levels of key homing molecules. Diabetes also reduced spiral arterial modification in mice through hypertrophy of smooth muscle. The reproductive challenges of diabetic women who have co-morbid immunological diseases merit further study. / Thesis (Master, Anatomy & Cell Biology) -- Queen's University, 2011-01-30 23:46:23.151

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