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 Dietary Fatty Acids On Cellular Calcium Handling Mechanisms In Cardiac Muscle
Funder
National Health and Medical Research Council
Funding Amount
$275,765.00
Summary
A major health problem in the developed countries is cardiovascular disease, which is manifest as high blood pressure, stroke, heart attack and abnormalities of heart rhythm, or cardiac arrhythmias. A western diet, ie. one high in animal fat, or saturated fats, may be to blame. Human epidemiological studies have shown that consumption of a diet high in saturated fats is correlated with a propensity to arrhythmias while a diet high in polyunsaturated fatty acids (PUFAs) can confer protection from ....A major health problem in the developed countries is cardiovascular disease, which is manifest as high blood pressure, stroke, heart attack and abnormalities of heart rhythm, or cardiac arrhythmias. A western diet, ie. one high in animal fat, or saturated fats, may be to blame. Human epidemiological studies have shown that consumption of a diet high in saturated fats is correlated with a propensity to arrhythmias while a diet high in polyunsaturated fatty acids (PUFAs) can confer protection from coronary heart disease and cardiac arrhythmias. The mechanisms underlying these effects are not fully understood. The contraction of the heart depends on changes in calcium inside the individual muscle cells. Abnormalities of the way calcium is handled in the cells leads to abnormalities of contraction and to a certain types of arrhythmia. Over the last 5 to 10 years, technological developments have enabled us to examine changes in calcium in living heart cells at microscopic level. It is possible to fill individual living cells with a fluorescent dye which changes either the magnitude or the wavelength of its fluorescence according to the ambient calcium concentration. Cells filled with these dyes are examined with a laser scanning confocal microscope, in which a very tightly focussed laser beam excites the dye and the resulting fluorescence is gathered by a computer controlled image analysis system. In this way we can measure the calcium concentration within the cells with a spatial resolution of about 1-1000 of a millimetre, and a time resolution of about 1-100 of a second. Using these techniques, we have found that supplementing the diet of rats with either PUFAs or saturated fats produces a dramatic change in the way that calcium is stored and released in their heart cells. This effect of dietary fats has not been reported before, and it may represent an important clue as to how these substances protect against many cardiac arrhythmias.Read moreRead less
Macrophage Migration Inhibitory Factor (MIF): Pathological And Therapeutic Significance In Post- Infarct Inflammation
Funder
National Health and Medical Research Council
Funding Amount
$547,577.00
Summary
Ischemic heart injury mediated by the inflammatory response has a significant impact on the prognosis. MIF is a central factor mediating and amplifying the inflammatory response but its role in heart disease remains largely untested. This project will study, for the first time, the crucial role of MIF in ischemic heart disease and will establish important experimental evidence for developing new anti-inflammation therapeutic strategies against ischemic heart injury.
Determinants Of Tissue Response To Nitric Oxide In Health And Disease
Funder
National Health and Medical Research Council
Funding Amount
$385,432.00
Summary
The endothelium, or inner lining layer of blood vessels, exerts a controlling influence on the tendency of blood vessels to constrict or dilate, and on the likelihood that clots will form by aggregation of platelets within the blood vessel. This process is largely mediated by release of nitric oxide (NO) from the endothelium. Importanly, NO is also the active chemical formed when patients are given nitroglycerine (NTG) for the treatment of angina pectoris. There is evidence that conditions predi ....The endothelium, or inner lining layer of blood vessels, exerts a controlling influence on the tendency of blood vessels to constrict or dilate, and on the likelihood that clots will form by aggregation of platelets within the blood vessel. This process is largely mediated by release of nitric oxide (NO) from the endothelium. Importanly, NO is also the active chemical formed when patients are given nitroglycerine (NTG) for the treatment of angina pectoris. There is evidence that conditions predisposing towards development of angina or of heart attacks (such as high cholesterol levels or high blood pressure) are associated with dysfunction of the endothelium, so that less NO is available. The precise cause of this process is uncertain. However, our recent experiments show that in patients with angina, circulating platelets respond poorly to NO. The research to be undertaken will explore the link between blood vessel and platelet function, examing the impact of race (Aboriginals compared to Caucasians) and coronary risk factors. It will also examine the implications of endothelial dysfunction on initial and long-term responses to NTG. The results will shed light on factors predisposing to development of heart attacks, and identify factors preventing optimal responses to anti-anginal treatment.Read moreRead less
Single-chain Antibodies For Directed Stem Cell Homing And Targeting Of Effector Cells In Vascular Disease
Funder
National Health and Medical Research Council
Funding Amount
$596,677.00
Summary
Regenerative cellular therapy e.g. with adult stem cells is a promising novel medical therapy. However, until now there is no reliable method to direct cells to areas where they are needed. We aim to develop a biotechnological approach based on genetically tailored antibody molecules that will allow cell targeting. As a pilot project we will test whether this approach improves lipid deposition and hardening of arteries.
The Role Of Aquaporins In Cardiac Ischaemia And Reperfusion
Funder
National Health and Medical Research Council
Funding Amount
$412,670.00
Summary
We are studying the important clinical problem of why the heart doesn't work very well after it has been deprived of blood. This may occur during a heart attack due to coronary artery disease and during cardiac surgery when the heart is stopped. The problem affects children as well as adults undergoing surgery. The reason the heart doesn't work well is related to energy supply and tissue damage caused during the shortage of blood supply and the period soon after flow is restored. Until the heart ....We are studying the important clinical problem of why the heart doesn't work very well after it has been deprived of blood. This may occur during a heart attack due to coronary artery disease and during cardiac surgery when the heart is stopped. The problem affects children as well as adults undergoing surgery. The reason the heart doesn't work well is related to energy supply and tissue damage caused during the shortage of blood supply and the period soon after flow is restored. Until the heart recovers, inadequate pump function may cause low blood flow problems downstream in vital organs such as the brain and kidneys. Under the microscope, a common feature of affected hearts is swelling of the cells and of the energy producing parts called mitochondria. We have identified, for the first time, unique proteins that allow water to move into and around cells of the heart. These proteins are called 'aquaporins' and early results suggest they are involved in how mitochondria deal with a shortage of blood supply. Interestingly, aquaporins are also affected in diseases that affect muscle strength, and we are using what is known in these diseases to further study the role of aquaporins in the heart. Our experiments to will test heart function from the level of the cell, all the way up to the whole heart. To improve the power of our experiments, we are working with mice that lack the special water transport proteins, as a prelude to developing drug therapy for this important problem. By manipulating aquaporin levels or function, we plan to improve heart preservation during periods of no blood flow, and after surgery. This would importantly reduce the risks associated with heart attack and cardiac surgery by avoiding complications associated with poor pump function.Read moreRead less
Therapeutic Silencing Of Egr-1 By Novel Catalytic Oligodeoxynucleotides For The Treatment Of Acute Myocardial Infarction
Funder
National Health and Medical Research Council
Funding Amount
$384,353.00
Summary
Heart attack remains a major health problem. We have identified a gene in the heart which is turned on in the first few hours of a heart attack. We have shown in principle that switching this gene off using a novel synthetic drug, reduces heart attack size. Our project assesses the long term effects of this drug on the heart using state of the art imaging when the the drug is administered in a clinically relevant manner. This study may faciliate a new treatment approach for this condition.
The Effect Of Ischaemia And Reperfusion On Sarcoplasmic Reticulum Calcium Handling In The Heart
Funder
National Health and Medical Research Council
Funding Amount
$236,208.00
Summary
Ischaemic heart disease is one of the most common causes of premature death in our society. Ischaemia occurs when the blood flow to the heart is obstructed so that oxygen cannot get to the muscle cells and metabolic waste products cannot be washed away. During ischaemia the concentration of free calcium within a cardiac muscle cell increases, and when blood flow is returned to the muscle this calcium concentration can increase further to very high levels. It is this change in calcium that is res ....Ischaemic heart disease is one of the most common causes of premature death in our society. Ischaemia occurs when the blood flow to the heart is obstructed so that oxygen cannot get to the muscle cells and metabolic waste products cannot be washed away. During ischaemia the concentration of free calcium within a cardiac muscle cell increases, and when blood flow is returned to the muscle this calcium concentration can increase further to very high levels. It is this change in calcium that is responsible for the reduced muscle force and abnormal cardiac rhythm that are the main cause of death. Cardiac muscle cells contain an intracellular compartment called the sarcoplasmic reticulum (SR). Under normal conditions the SR stores large amounts of calcium in order to maintain a low concentration of calcium free within the cell. However, even in a resting cell, calcium can escape from the SR through channels in SR membrane. We are using a state-of-the-art microscope to visualize these tiny packets of calcium, termed calcium sparks, as they travel through the SR membrane. If the number of calcium sparks increases, the amount of calcium being released from the SR also increases. We are studying what happens to calcium sparks, and therefore SR calcium release, during ischaemic heart disease. We are also examining the effect of ischaemic heart disease on the concentration of calcium within the SR and the activity of the transporters that pump calcium back into the SR. We hope to show that a change in the way the SR regulates calcium contributes to ischaemic damage. Understanding how changes in SR function alter muscle force and cardiac rhythm will help in the development of drugs to protect against ischaemic damage.Read moreRead less
Reduced Ischaemic Tolerance In The Aged Myocardium: The Role Of Adenosine And Adenosine Receptors
Funder
National Health and Medical Research Council
Funding Amount
$470,250.00
Summary
Despite a decline in deaths rates due to heart disease over the last decade, cardiovascular disease remains the single greatest cause of premature death in individuals over 65 years of age. It accounts for a major and increasing portion of health care costs. Coronary artery disease affects 50% of those older than 65, and with the ageing of our population it is estimated that the elderly population will nearly double from 13-14% to 25% over the next 30 years. Unfortunately, it appears that the ag ....Despite a decline in deaths rates due to heart disease over the last decade, cardiovascular disease remains the single greatest cause of premature death in individuals over 65 years of age. It accounts for a major and increasing portion of health care costs. Coronary artery disease affects 50% of those older than 65, and with the ageing of our population it is estimated that the elderly population will nearly double from 13-14% to 25% over the next 30 years. Unfortunately, it appears that the aged heart is less resistant to disease and injury, contributing to the increase in mortality with ageing. The reasons are not known. This research project will attempt to identify molecular changes which occur in the heart during ageing which may lead to a decline in ability to withstand disease and injury. The research will specifically examine the possibility that a key protective response, known as the adenosine receptor system, is somehow impaired or abnormal in the cells of the aged heart. If it is found that this process is impaired, the research will attempt to rectify this abnormality using new genetic therapy techniques to switch on the heart's own intrinsic defense mechanisms. This may ultimately open up new avenues for specific therapeutic approaches to treatment of ischaemic heart disease in the elderly.Read moreRead less
Structural And Functional Alterations Of Sarcomeric Proteins In Reperfused Myocardium
Funder
National Health and Medical Research Council
Funding Amount
$271,786.00
Summary
Coronary artery disease remains the major cause of mortality for the adult population in our society. Despite the advances of coronary artery bypass surgery and medical treatment for reperfusion of occluded coronary arteries, the problem of impaired pump function of the heart remains a major obstacle. Although blood flow can be restored to the jeopardised heart muscle by either clot dissolving drugs, balloon angioplasty, or coronary artery surgery, the heart muscle may not regain pump function f ....Coronary artery disease remains the major cause of mortality for the adult population in our society. Despite the advances of coronary artery bypass surgery and medical treatment for reperfusion of occluded coronary arteries, the problem of impaired pump function of the heart remains a major obstacle. Although blood flow can be restored to the jeopardised heart muscle by either clot dissolving drugs, balloon angioplasty, or coronary artery surgery, the heart muscle may not regain pump function for days to weeks after the event. This delayed recovery of pump function, known as myocardial stunning, can lead to heart failure and slow down a patient's recovery from heart surgery or heart attack. The cause of this myocardial stunning is unknown. We suggest that stunning results from damage to essential proteins in the contractile apparatus of the heart, which requires a prolonged time period for repair. This project aims to identify the site and extent of protein damage occurring in the heart following interruption and subsequent restoration of cardiac blood flow. In concert with this, we seek to determine the mechanism of protein damage. The findings of this project should allow us to subsequently investigate new treatment approaches for acute pump dysfunction in patients with ischaemic heart disease.Read moreRead less