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. / Applied Science, Faculty of / Graduate

Diabetes mellitus is a metabolic disease characterised by hyperglycaemia resulting from defects in insulin secretion, insulin action, or both. The leaf extract of Leonotis leonurus and its active compound marrubiin, have been shown to possess anti-diabetic, antiplatelet, anti-inflammatory and anti-coagulation activity. In the present study, the mechanism by which L. leonurus and marrubiin exert their anti-diabetic properties, the cross-talk between the peripheral tissues and a nano drug delivery system were investigated. Marrubiin in the plant extract was effectively quantified by an optimised reversed phase highperformance liquid chromatography (HPLC) protocol using a pentafluorophenyl (PFP) column with water and acetonitrile (50:50) as mobile phase, and a flow rate of 1ml/min. The chemical structure was determined using liquid chromatography-tandem mass spectroscopy LC-MS/MS. Real-time quantitative polymerase chain reaction (RT-qPCR) gene expression of selected adipokines and proteins implicated in Type-2 diabetes (T2D) were investigated in specific peripheral tissues isolated from an in vivo obese rat model. An in vitro cell culture model was used to determine the crosstalk between the peripheral tissues and pancreatic (INS-1E) β-cells. Various nanoformulations of L. leonurus extract were prepared and their effect on cytotoxicity (in Chang liver and INS-1 cells), insulin-mediated glucose uptake (Change liver cells) and insulin secretion (INS-1) were investigated. The average yield of marrubiin from the plant extract was 10% (n=3), with a molecular mass of 333.20Da and a molecular formula of C20H29O4 +. Results from the in vivo study showed that the L. leonurus extract significantly (p<0.05) enhanced the gene expression of adiponectin, peroxisome proliferator-activated receptor gamma (PPAR-γ), glucokinase (GK), uncoupling protein-2 (UCP-2) and reduced leptin in adipose tissue, but resistin, glucose transporters (GLUT), fatty acid synthase (FAS), insulin receptor substrate -1 (IRS-1) and phosphoenolpyruvate carboxykinase (PEPCK) gene expression were not affected. Marrubiin decreased gene expression of leptin and resistin, and increased IRS-1 and glucokinase in adipose tissue. In liver and muscle tissues, marrubiin and the L. leonurus extract reduced gene expression of PPAR-γ, IRS-1, glucokinase and PEPCK. In the in vitro crosstalk study (under normoglycaemic and hyperglycaemic conditions), conditioned medium from 3T3-L1 cells significantly (p<0.01) enhanced insulin secretion. This was not observed in INS-1E cells exposed to muscle- and liver-conditioned medium, respectively. The in vitro studies using a nanostructured lipid formulation (NLC) of the plant extract was not cytotoxic to either INS-1 and Chang liver cells. The NLC formulation significantly (p<0.05) enhanced glucose uptake in Chang liver cells and improved chronic insulin release in INS-1 cells (p<0.05). Based on the above findings from the in vivo and in vitro studies, both L. leonurus and marrubiin exerted an insulinotropic effect via adipose tissue on pancreatic β-cells. The findings in the in vivo study showed that marrubiin and the L. leonurus extract were employing their major anti-diabetic action via the adipose tissue.

Diabetes associated complications make management during exercise complex (Brugnara, Vinaixa, Murillo, Samino, Rodriguez, Beltran, Lerin, Davison, Correig & Novials, 2012). Research on the prevention of such challenges is of paramount importance. The aim of this study was to determine the effects of three different carbohydrate supplementation protocols on blood glucose levels after every 10 minutes of a 60 minute exercise bout at 65 to 75 % HRR on the treadmill as well as every half hour during a two hour post exercise recovery period. The three protocols implemented after a standardized pre-exercise meal were: control protocol (no carbohydrate supplementation), protocol 1 (one carbohydrate supplementation of 15 grams given at 30 minutes) and protocol 2 (two carbohydrate supplementation of 15 grams given at 30 minutes and 45 minutes). A total of 32 participants took part in the study (Mean age: 32.84 ±12.12). All participants were submitted to all three protocols. Statistical and practical significant differences were found between blood glucose levels of protocol 0 and protocol 1 (MDIF = 2.62 ± 3.99 mmol.L--‐1) at 20 minutes of the exercise duration (p=.024;d=0.42). Statistical and practical significant differences in blood glucose levels with protocol 0 rendering the higher glucose values were also found between protocols 0 and 2 at 10 minutes (MDIF = 3.44 ± 5.54 mmol.L--‐1; p=.001;d=0.62), 20 minutes (MDIF = 3.32 ± 5.23 mmol.L--‐1; p=.001;d=0.63) and 30 minutes of exercise (MDIF = 2.81 ± 5.40 mmol.L--‐1; p=.006;d=0.52) as well as between the mean minimum (M0 = 9.49 ± 4.51 mmol.L--‐1 and M2 = 7.28 ± 4.07 mmol.L--‐1; p=.013;d=0.46), mean maximum (M0 = 12.73 ± 5.51 mmol.L--‐1 and M2 = 10.07 ± 4.63 mmol.L--‐1; p=.015;d=0.46) and overall mean (M0 = 9.07 ± 4.88 mmol.L--‐1 and M2 = 8.53 ± 4.25 mmol.L--‐1; p=.011;d=0.48) with protocol 0 rendering the higher glucose values in all these comparisons. It was concluded that carbohydrate supplementation during exercise affects blood glucose levels positively particularly considering the significant difference found between protocol 0 and 2. Whilst protocol 2 also resulted in less fluctuations in the blood glucose levels during exercise and minimum, overall mean and maximum blood glucose values were closer to “normal/safe” range, there was no conclusive evidence that protocol 2 was better than protocol 1.

The syntheses of bis(1R-imidazole-2/4-carboxylato)oxidovanadium(IV) complexes was successfully carried out and the complexes were isolated in the solid state. The coordinated water was confirmed by elemental analyses, and single crystal XRD. The complexes were therefore distorted octahedral rather than square planar due to the coordination of water at the sixth position. The reaction of the vanadyl ion (VO2+) with imidazole-4-carboxylic acid (Im4COOH), imidazole-2-carboxylic acid (Im2COOH) and methylimidazole-2-carboxylic acid (MeIm2COOH), respectively, in the presence of small bioligands (bL) [oxalate (Ox), lactate (Lact), and phosphate (Phos)] and high molecular weight (HMM) human serum proteins [albumin (HSA) and transferrin (hTf)] were studied in aqueous solution using potentiometric acid base titrations under oxygen and carbon dioxide–free conditions. The data obtained from these titrations was used to calculate the binary and ternary stability constants using the programme HYPERQUAD. The overall stability constants for VO2+-L-Ox system (log β1111 = 18.9, 18.79 and 19.86), VO2+-L-Lact system (log β1111 = 21.83, 20.98 and 22.86), and VO2+-L-Phos system (log β1111 = 27.35, 24.16 and 27.42) (for L= Im4COOH, Im2COOH and MeIm2COOH, respectively) were obtained. The species distribution diagrams showed that under physiological pH the following ternary and quaternary species; [(VO)L(bL)], and [VO(L)(bL)(OH)], would dominate provided that the competition with serum proteins is not too strong. These species were also confirmed by HPLC, LC-MS and EPR. The overall stability constants for the VO2+-L-HSA system (log β2,1,1,0 = 24.3, 23.7 and 24.7), and for the VO2+-L-hTf system (log β2,2,1,0 = 31.1, 30.8, 36.4 for L = Im4COOH, Im2COOH and MeIm2COOH, respectively), suggesting stronger binding of transferrin. The formation constants for the formation of binary (VO(IV) and the proteins) were 9.1 and 13 for log β11, and 20.9 and 25.2 for β12, for human serum albumin and human serum transferrin respectively. The species distribution diagrams for the proteins (HMM) with oxidovanadium(IV) under physiological pH was dominated by VO(HMM)2, VOL(HMM) for unsubstituted Im4COOH and Im2COOH, however, for the N-substituted MeIm2COOH, the species distribution diagrams under physiological pH, were dominated by VOL2, VO(HMM)2 and VO2L2(HMM). These species were further confirmed by HPLC, MALDI-TOF-MS and EPR. The glucose stimulated insulin secretion (GSIS) action of the complexes was investigated using INS-1E cells at 1μM concentration which was established through cytotoxicity studies via the MTT assay. The vanadium salt (VOSO4), cationic vanadium(IV) complex ([VO(MeImCH2OH)2]2+) were also included in the GSIS study in addition to the three neutral complexes [VO(Im4COO)2, VO(Im2COO)2 and VO(MeIm2COO)2] for comparison. The neutral complexes, especially VO(MeIm2COO)2, showed promising results in the stimulation of insulin secretion than the cationic complex and the vanadium salt.

The aim of this study was to assess the effects of a twelve-week hydrotherapy group exercise programme on selected health-related fitness variables in older women with type II diabetes mellitus. This study included the testing of blood glucose levels, blood anthropometrical profile, body mass, height, body mass index, waist circumference, waist-to-hip ratio, upper body flexibility, lower body flexibility, grip strength, upper body and lower body muscular strength and endurance as well as aerobic endurance. Descriptive and inferential statistical techniques were used for this study utilising a quasiexperimental research design. A comparison group pre-test and post-test experimental design was employed at the Nelson Mandela Metropolitan University Biokinetics and Sports Science Unit. Approximately 16 senior female participants took part in the study. Participants were identified through convenience sampling and snowball sampling, of which, all the participants were clinically diagnosed with type II diabetes mellitus and had completed the study. The hydrotherapy participants (experimental group), took part in water-based (hydrotherapy) exercises three times a week for a period of twelve weeks. The hydrotherapy exercises began with a light half-hour workout per session and were progressively increased in intensity, duration, and number of the exercises performed. The participants not participating in the hydrotherapy exercises (control group) were instructed to remain sedentary throughout the duration of the intervention period. The dependant variables were gathered as raw data and analysed using descriptive statistics to form the means, standard deviations, medians, minimum and maximum values. Post hoc analysis was performed to determine whether differences existed between the experimental group and control group. Cohen’s D test was used to determine pre- and post-test differences for both groups to determine practical significance. An analysis of the results revealed significant improvements in some of the selected health and physical fitness parameters such as, upper body and lower body flexibility, upper and lower body muscular strength and endurance, as well as aerobic endurance. iii The aim and objectives of the study in exploring the effect of hydrotherapy as an intervention strategy to promote health and physical fitness in persons with type II diabetes mellitus were supported by the data collected in the pre-test and post-test analyses of the variables.

Type 2 diabetes mellitus (DM) is a progressive disease characterised by hyperglycaemia caused by defects in insulin secretion and insulin action. In early stages of type 2 DM, dietary and lifestyle changes are often sufficient to control blood glucose levels. However, over time, many patients experience β cell dysfunction and require insulin therapy, either alone or in combination with oral agents. There are guidelines available to structure the management of this disease state, including both the use of oral hypoglycaemic agents and or insulin. Besides health complications, there are economic burdens associated with the management of type 2 diabetes mellitus. The aim of this study was to determine the management of type 2 DM in a South African sample group of patients drawn from a large medical aid database. The objectives of the study were: to establish the prevalence of type 2 DM relative to age, examine the nature of chronic comorbid disease states, establish trends in the prescribing of insulin relative to other oral hypoglycaemic agents, investigate cost implications, and determine trends in the use of blood and urine monitoring materials by patients. The study was quantitative and retrospective and descriptive statistics were used in the analysis. DM was found to be most prevalent amongst patients between 50 and 59 years old. Results also demonstrated that 83% of DM patients also suffered from other chronic comorbid diseases, with cardiovascular diseases, especially hypertension and hypercholesterolaemia being the most prominent. This study also revealed that DM is predominantly managed with oral hypoglycaemic agents. Changes in drug prescribing, for chronic disease states such as DM may have medical, social and economic implications both for individual patients and for society and it is envisaged that the results of this study can be used to influence future management of DM. Keywords: Pharmacoepidemiology, management, type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is rapidly emerging as one of the greatest global health issues of the 21st century. Insulin-resistance is a condition associated with T2DM and in the cell it is defined as the inadequate strength of insulin signalling from the insulin receptor downstream to the final substrates of insulin action involved in multiple metabolic, gene expression, and mitogenic aspects of cellular function. To investigate the potential mechanisms involved in the development of insulin-resistance, two in vitro liver cell models were established using palmitate or a combination of insulin and fructose as inducers. The development of insulin-resistance was determined via the capacity of the hepatocytes to maintain normal glucose metabolism functionality by measuring hepatic gluconeogenesis and glycogenolysis. It was established that the treatments induced the development of insulinresistance after 24 hours chronic exposure. Previous studies have investigated the potential of Sutherlandia frutescens extracts as therapeutic agents for insulin-resistance. The aim of this study was thus to investigate the ability of a hot aqueous extract of S. frutescens to reverse the insulin-resistant state, via measuring gluconeogenesis and glycogenolysis, the associated changes in cellular physiology (lipid accumulation, oxidative stress, and acetyl- CoA levels), and changes in mRNA expression. The results showed that S. frutescens had a significant effect on reversing the insulin-resistant state in both models of insulin-resistance. Furthermore, S. frutescens was capable of reducing lipid accumulation in the form of triacylglycerol in the high insulin/fructose model, while this was unaffected in the palmitate model. However, S. frutescens did reduce the accumulation of diacylglycerol in the palmitate model. Oxidative stress, seen to be associated with the insulin-resistant state, was successfully treated using the extract, as indicated by a reduction in reactive oxygen species. However no change was seen in the nitric oxide levels, in either model. Interestingly, although S. frutescens had no effect on the level of acetyl-CoA in the insulin/fructose model, it was found to increase this in the palmitate model. It is suggested that this may be due to increased β-oxidation and metabolic activity induced by the extract. The analysis of mRNA expression gave some insight into possible mechanisms by which insulin-resistance develops, although the results were inconclusive due to high variability in samples and the possibility of the RNA being compromised. Future studies will address this issue. The results of this study reflect different proposed clinical causes of insulin-resistance through the responses seen in the two cell models. These indicate that liver steatosis and insulin-resistance are induced by high palmitate as well as high insulin and fructose levels, and reversed by S. frutescens. Therefore the potential of S. frutescens to be used as a therapeutic agent in the treatment of insulin-resistance is indicated by this study.

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In patients with diabetes, hyperglycemia leads to functional impairment of endothelial cells (ECs) and microangiopathy. Inflammation and endothelial dysfunction (ED) have been associated with the development of several cardiovascular complications. Concentration of methylglyoxal (MG) - a highly reactive aldehyde is increased in diabetes. In a non-pathological state, MG is detoxified by the enzymes glyoxalase-1 (GLO1) and glyoxalase 2 in presence of glutathione. This thesis examines the role of MG accumulation in ECs and bone marrow cells (BMCs), with the consequences it has for their function. To this end, a transgenic mouse model was used in which the human enzyme GLO1 is overexpressed in the vasculature By using a GLO1 overexpressing mouse model studies described here examined the contribution of MG-induced inflammation in vivo to cardiovascular complications of diabetes, namely diabetic heart failure and peripheral vascular disease. This study confirmed that accumulation of MG leads to inflammation and cell death, and further explained how MG affects the role of ECs in development of the heart failure and BMCs in the revascularization. Overexpression of GLO1 in the vasculature diminished MG-induced inflammation, reduced EC death and delayed and limited the loss of cardiac function in streptozotocin (STZ)-induced diabetic mice (Chapter 2). The in vitro part of this study showed that MG and tumor necrosis factor (TNF- have a synergistic effect on cell death (Chapter 3). Overexpressing the GLO1 in BMCs only, restored neovascularization in ischaemic tissue of mice with STZ-induced diabetes (Chapter 4). Taken together, the results of this thesis suggest that hyperglycemia increased MG leads to endothelial inflammation, EC death and decreased angiogenic potential of BMCs. Furthermore, this MG-induced inflammation and reduced cell function observed, identifies a potential target for therapy of the cardiovascular complications seen in diabetes.

This investigation was concerned with measuring aspects of cardiac function in conscious control, diabetic, hypertensive control, and hypertensive diabetic rats. Preliminary studies were conducted to determine catheter suitability and acute responses to atropine and angiotensin II in conscious animals. The catheter-manometer was tested using a square wave impact and was shown to accurately reproduce a left ventricular pressure pulse. Intravenous atropine caused both heart rate and left ventricular +dP/dt to rise. Intravenously administered angiotensin II caused systolic blood pressure to increase dramatically. In this case heart rate fell and +dP/dt was elevated. Hypertension was induced with deoxycorticosterone acetate (DOCA) and saline drinking water. Rats were first made diabetic with streptozotocin (60 mg/kg; i.v.). One week following this, subcutaneous DOCA (25 mg/kg) was administered twice weekly and all animals received saline drinking water. Following 2 and 5 weeks of DOCA treatment rats were catheterized and resting cardiovascular function was measured. DOCA treatment caused increased systolic and diastolic blood pressures to occur in control and diabetic rats at 2 and 5 weeks. Bradycardia was also observed in DOCA-diabetic and DOCA-control rats at 2 and 5 weeks of treatment. Two and 5 week hypertensive diabetic and control rats exhibited elevated -dP/dt and +dP/dt. The rate of contraction was shown to be proportional to the magnitude of systolic blood pressure in all treatment groups. It is concluded that diabetic rats and control rats did not differ in their response to hypertension after 5 weeks of DOCA treatment. / Medicine, Faculty of / Anesthesiology, Pharmacology and Therapeutics, Department of / Graduate