Biochemical Basis Of Islet Beta-cell Compensation And Failure In Normal Pregnancy And Gestational Diabetes Mellitus
Funder
National Health and Medical Research Council
Funding Amount
$480,828.00
Summary
The factors causing the current world-wide crisis of rapidly rising diabetes prevalence remain poorly understood. Of potential major importance, however, is the hypothesis that abnormalities in the maternal metabolic environment, as occur in gestational diabetes (GDM) (diabetes that develops in pregnancy), result in abnormal development of metabolic systems in the baby resulting in higher risk of adult onset diabetes in the babies. Therefore, it is of importance to understand the mechanisms caus ....The factors causing the current world-wide crisis of rapidly rising diabetes prevalence remain poorly understood. Of potential major importance, however, is the hypothesis that abnormalities in the maternal metabolic environment, as occur in gestational diabetes (GDM) (diabetes that develops in pregnancy), result in abnormal development of metabolic systems in the baby resulting in higher risk of adult onset diabetes in the babies. Therefore, it is of importance to understand the mechanisms causing GDM, such that effective measures can be developed to counter this passing on of diabetes risk from mother to baby. It is known that a key factor causing GDM is failure of maternal pancreatic islet beta-cells to compensate for increased demands for insulin production in pregnancy. Poorly understood, however, are the cellular mechanisms of islet beta-cell compensation in normal pregnancy and failure of this compensation in GDM pregnancy. We have recently shown that there is a pathway of fat metabolism (triglyceride- free fatty acid cycle) within the islet beta-cell that has an important role in amplyfing insulin secretion necessary to maintain normal blood glucose and protecting the islets from failure in obese rats. The major focus of this project is to test the hypothesis that this pathway has a key role in the adaptation of pancreatic islets to normal pregnancy and its dysfunction contributes to the causation of GDM. Of great interest from preliminary findings is that a master regulator of glucose and fat metabolism, PGC1alpha, is markedly reduced in islets during normal pregnancy. Studies will also be directed to PGC1alpha's role in islet adaptation to pregnancy and failure in GDM. We expect that successful completion of this project will lead to the development of highly targeted counter measures to prevent GDM and to slow and reverse the current epidemic of diabetes.Read moreRead less
Exertional Dyspnoea With Increased Filling Pressure - Mechanisms And Treatment Strategies
Funder
National Health and Medical Research Council
Funding Amount
$387,793.00
Summary
Patients with early heart disease often present with shortness of breath with exercise, as myocardial reserve at that stage is usually sufficient to maintain normal function at rest . Indeed, much myocardial dysfunction may originate from the modern lifestyle, including inactivity, obesity, the metabolic syndrome and type II diabetes. The potential benefits of making a definitive early diagnosis are large, because it seems more likely that an impact can be made on the disease process (and theref ....Patients with early heart disease often present with shortness of breath with exercise, as myocardial reserve at that stage is usually sufficient to maintain normal function at rest . Indeed, much myocardial dysfunction may originate from the modern lifestyle, including inactivity, obesity, the metabolic syndrome and type II diabetes. The potential benefits of making a definitive early diagnosis are large, because it seems more likely that an impact can be made on the disease process (and therefore, outcome) than with late stage disease. Current treatment strategies are expensive and because they are directed at end-organ damage (heart failure, heart attacks etc), rather ineffective. This multispecialty, multidisciplinary group will undertake a series of unique studies aimed at identifying early cardiovascular disease. The strategy will involve detection of abnormal filling behaviour at stress echocardiography, with randomization into longterm and short-term trials to examine various therapeutic strategies. Sensitive new cardiovascular imaging techniques will be used to detect preclinical abnormalities in the structure and function of the heart and vasculature, facilitating a mechanistic understanding of the process of increasing filling pressure with exercise.Read moreRead less
The Effect Of CPAP On Erectile And Endothelial Dysfunction In Impotent Men With Obstructive Sleep Apnea
Funder
National Health and Medical Research Council
Funding Amount
$609,559.00
Summary
Erectile dysfunction is common in men with obstructive sleep apnea, due to vascular damage, which leads to heart attack. CPAP is the preferred treatment for patients with OSA because of its well-proven ability to decrease sleepiness and improve blood pressure control. This study will establish if CPAP can also improve erectile and vascular endothelial dysfunction. These results will shed light on the mechanisms that underpin the relationship between OSA and Erectile Dysfunction.
The Role And Function Of Macrophages In Cellular Xenograft Rejection
Funder
National Health and Medical Research Council
Funding Amount
$323,250.00
Summary
The long term objective of this project is to develop pig insulin secreting tissue as a treatment for type 1 diabetes. At present the main barrier to this is rejection. In paricular a type of white blood cell called macophages has an important role in causing the rejection seen in xenotransplantation (the transplantation of pig tissue into humans). Our reseach group has made novel observations which show that the way macrophages respond to a xenotransplant is different to the way it behaves to t ....The long term objective of this project is to develop pig insulin secreting tissue as a treatment for type 1 diabetes. At present the main barrier to this is rejection. In paricular a type of white blood cell called macophages has an important role in causing the rejection seen in xenotransplantation (the transplantation of pig tissue into humans). Our reseach group has made novel observations which show that the way macrophages respond to a xenotransplant is different to the way it behaves to the transplant of an organ from the same species. In the rejection of pig insulin secreting tissue, macrophages are able to respond in the absence of ongoing signals from T cells. This project aims to identify the receptors on macrophages that are responsible for this response. In particular those receptors that are important for facilitating the migration of macrophages to the transplant site and the receptors that allow macrophages to distinguish self from non-self will be analysed. Hopefully these receptors will be used as targets for new therapeutic agents that could be used to prevent the strong rejection response that occurs when pig insulin secreting tissue is transplanted into humans.Read moreRead less
The current epidemic of type 2 diabetes represents a major global health problem, with over 7% of the Australians suffering the disease. While there is a well-established relationship between obesity and insulin resistance, the majority of overweight individuals do not develop type 2 diabetes because their pancreatic beta-cells compensate with enhanced insulin secretion. It is the failure of beta-cell compensation that is fundamental to the development of diabetes. The beta-cell is a highly spec ....The current epidemic of type 2 diabetes represents a major global health problem, with over 7% of the Australians suffering the disease. While there is a well-established relationship between obesity and insulin resistance, the majority of overweight individuals do not develop type 2 diabetes because their pancreatic beta-cells compensate with enhanced insulin secretion. It is the failure of beta-cell compensation that is fundamental to the development of diabetes. The beta-cell is a highly specialised cell with a unique metabolic profile and differentiation specifically geared towards making these cells able to sense fluctuations in circulating glucose levels and secrete insulin accordingly. We propose that in susceptible individuals, a gradual rise in blood glucose (hyperglycaemia) and lipid levels resulting from increasing obesity and insulin resistance leads to a loss of the unique expression pattern of genes necessary for appropriate insulin secretion. This exacerbates hyperglycaemia, which causes further beta-cell dedifferentiation and eventually the death of beta-cells by apoptosis. We have recently found evidence in several models of diabetes that supports this hypothesis. We propose to use animal studies and cell culture systems to investigate the following hypotheses important for our understanding of beta-cell failure and progression to diabetes: 1) The loss of beta-cell phenotype (dedifferentiation) underlies the loss of insulin secretory function in failing beta-cells. 2) Hyperglycaemia plays a critical role regulating the progression to beta-cell dedifferentiation. 3) The overexpression of key candidate gene products play an integral role linking hyperglycaemia to the loss of beta-cell secretion. 4) Endoplasmic reticulum stress is necessary for beta-cell death in diabetes. Our studies will make a major contribution to our understanding of why beta-cells fail in diabetes and aim to provide novel therapeutic targets in the treatment of diabetes.Read moreRead less
Investigation Of The Roles Of Protein Kinase C Epsilon In Insulin Secretion And Insulin Clearance
Funder
National Health and Medical Research Council
Funding Amount
$627,148.00
Summary
The rise in blood insulin levels after a meal normally reduces blood sugar levels by increasing glucose uptake and storage in certain tissues, especially muscle. Type 2 diabetes is characterized in part by a failure of the pancreas to produce adequate insulin in response to increases in blood sugar. This loss of insulin secretion has been strongly linked to increases in the availability of fat, although the reasons for this are not clear. We have recently found that mice lacking a specific enzym ....The rise in blood insulin levels after a meal normally reduces blood sugar levels by increasing glucose uptake and storage in certain tissues, especially muscle. Type 2 diabetes is characterized in part by a failure of the pancreas to produce adequate insulin in response to increases in blood sugar. This loss of insulin secretion has been strongly linked to increases in the availability of fat, although the reasons for this are not clear. We have recently found that mice lacking a specific enzyme (protein kinase C epsilon) are much less susceptible to the problems in dealing with blood sugar that are caused by a high fat diet. We showed that this is due partly to improved insulin secretion, and also to a slower breakdown of insulin by the liver, which increases its availability to target tissues. The aim of this project is to investigate the mechanisms occurring in the liver and in the pancreas by which this enzyme contributes to improved insulin action. Firstly, we will examine insulin uptake in liver cells, to investigate how the enzyme controls this process. Secondly, we will determine the mechanism through which the activation of the enzyme, upon increased fat supply to pancreatic beta-cells, reduces insulin secretion in response to glucose. Finally, will assess the relative importance of these two actions of the enzyme in improving the control of blood sugar levels. This work will lead to a better understanding of the mechanisms by which fat oversupply, and hence obesity, can play a role in the development of Type 2 diabetes, so that they can be targeted both for the development of new and more effective treatments for the disorder and for prevention of its onset.Read moreRead less
Efficacy And Mechanisms Of Exercise Training In Diastolic Heart Failure
Funder
National Health and Medical Research Council
Funding Amount
$385,250.00
Summary
Heart failure is modern epidemic which presents a significant public health burden, due to a high mortality, frequent hospital admissions and impaired functional capacity. Although the typical heart failure patient presents with a reduced contractile function, many patients have typical heart failure symptoms but with normal contraction. The problem in these patients seems to relate to the heart's ability to fill with blood, and this entity is known as diastolic heart failure (DHF). This syndrom ....Heart failure is modern epidemic which presents a significant public health burden, due to a high mortality, frequent hospital admissions and impaired functional capacity. Although the typical heart failure patient presents with a reduced contractile function, many patients have typical heart failure symptoms but with normal contraction. The problem in these patients seems to relate to the heart's ability to fill with blood, and this entity is known as diastolic heart failure (DHF). This syndrome is most frequently due to ischemic or hypertensive heart disease, and most commonly occurs in the elderly. The optimal management of DHF is not well defined, although some drug trials are currently in progress. A number of studies have shown exercise training to improve functional capacity by 15-20% in typical heart failure. However, training has not so far been trialled in DHF. In this multicenter, multi-disciplinary study, we will study a training and control group to determine whether exercise capacity and DHF symptoms are responsive to exercise training. This work will teach us about the optimum exercise prescription, in terms of the duration and nature of training, as well as the safety and effectiveness of exercise training. By using a number of sensitive measurements of heart and vessel function (in which our group has special expertise), we will identify whether exercise training exerts its effect through improvement in vascular function and myocardial properties. If successful, the clinical implications of this study are that; 1. Exercise training will be adopted to improve functional capacity and symptoms of DHF 2. The merits of aerobic and strength training will be identified in DHF 3. Abnormal blood vessel function will be identified as a major and reversible contributor to DHFRead moreRead less
Functional Suicide Of Selected Dendritic Cells By Cytochrome C: An In Vivo Model Lacking Cross-presentation
Funder
National Health and Medical Research Council
Funding Amount
$597,476.00
Summary
Certain white blood cells (dendritic cells) activate the immune system, especially its T cells. Infection of such cells elicits killer T cell responses. However not all infections infect dendritic cells. In such cases, the infectious material is eaten by dendritic cells and moved to certain areas within the cell. This process is called cross-presentation and how important it is during various diseases remains moot. We now have a model of testing this by eliminating these cross-presenting cells.
The current treatment for diabetes involves diet, drugs and insulin treatment. While these are satisfactory for some adult onset diabetes, it is clear that in juvenile diabetes, the disease can progress in the presence of careful insulin dosage. It is apparent that the whole islet as a functional unit is likely to give the best control of diabetes, as when patients are transplanted with whole or segments of pancreas from human donors, as not only is there an improvement in their diabetic status, ....The current treatment for diabetes involves diet, drugs and insulin treatment. While these are satisfactory for some adult onset diabetes, it is clear that in juvenile diabetes, the disease can progress in the presence of careful insulin dosage. It is apparent that the whole islet as a functional unit is likely to give the best control of diabetes, as when patients are transplanted with whole or segments of pancreas from human donors, as not only is there an improvement in their diabetic status, the vessel lesions improve. Transplantation therefore offers a new therapy to diabetic patients for reversal of their disease and improvement in the serious side affects found in the eye, kidney and blood vessels. However, transplantation introduces a problem in that there is simply not sufficient human islets available for organ or islet transplantation, and in this light, animals are being examined as a possible source of islets. This is called xenografting or xenotransplantation. Of all the animal species, the pig is the most suitable donor for a variety of reasons, for example similar control of blood sugar to humans. The ultimate aims of the study are to examine possible genetic modifications that would allow the production of transgenic pig islets for transplantation to humans for the treatment of diabetes. The focus of the proposed studies is to elucidate the optimal combinations using mouse models. Importantly this study will establish the proof of principle and provide information on the genes that will be useful to finally genetically modify pigs for clinical use.Read moreRead less