Effects And Mechanisms Of Direct Cardiac Compression In Interruption Of Myocardial Remodelling In Chronic Heart Failure.
Funder
National Health and Medical Research Council
Funding Amount
$392,250.00
Summary
Heart failure (HF) is a disease where the heart pumping function is insufficient to provide adequate blood supply to the rest of the body. It is a highly debilitating disease affecting nearly 10 million people worldwide and has a <50% one-year survival in severe cases. Despite significant advances in pharmacotherapy, heart transplant is the only alternative for severe HF but is restricted by lack of donor organs to only ~ 5% of those requiring it. Research has shown that progression of HF is ....Heart failure (HF) is a disease where the heart pumping function is insufficient to provide adequate blood supply to the rest of the body. It is a highly debilitating disease affecting nearly 10 million people worldwide and has a <50% one-year survival in severe cases. Despite significant advances in pharmacotherapy, heart transplant is the only alternative for severe HF but is restricted by lack of donor organs to only ~ 5% of those requiring it. Research has shown that progression of HF is related to many subsequent changes after an initial insult. In addition to pumping failure, HF is associated with deranged compensatory responses such as neurohumoral over-activation, heart chamber enlargement, loss of functional cells, increase of inflammatory mediators and changes in cardiac skeleton (extracellular matrix). The changes in the heart are collectively known as remodelling. Mechanical heart assist is now considered a potential destination therapy for severe HF, superior to pharmacotherapy alone. Improvement of cardiac pumping function and even successful weaning from devices has been reported, along with observations of reverse remodelling. The success of this approach has been limited however, particularly with HF due to coronary disease, the most prevalent form. We developed a novel HeartPatch mechanical assist device to compress the heart from its outer surface. It gives support to both main chambers and avoids blood contact, a feature of currently available devices associated with complications such as blood clotting and infection. Our device has proved effective in animals with acute HF and even with cardiac arrest. We propose to study the effects of our device on the process of remodelling in HF with coronary disease in a controlled manner. The project will enhance understanding of the mechanisms involved in reverse remodelling and further the development of a device which may potentially benefit many severe HF patients.Read moreRead less
Regulation Of Endogenous Heart Regeneration By An Anti-fibrotic MicroRNA.
Funder
National Health and Medical Research Council
Funding Amount
$440,949.00
Summary
In contrast to the adult heart, the newborn heart undergoes scarless healing following a heart attack. The molecular mechanisms that govern heart regeneration in newborn mammals are not fully understood. The goal of the current study is to determine the role of a recently identified family of molecules known as microRNAs in the regulation of scarless healing. We propose a novel strategy for re-activation of microRNAs in the adult heart to promote regeneration following heart attack.
Ischaemia-induced Sarcolemmal Changes And Their Role In Ins(1,4,5)P3 Generation And Arrhythmogenesis
Funder
National Health and Medical Research Council
Funding Amount
$468,750.00
Summary
Studies in our laboratory at the Baker Heart Research Institute over the last several years have identified a novel mechanism causing the development of arrhythmias, a primary cause of sudden cardiac death in heart failure as well as during an acute heart attack caused by acutely reduced blood flow. The reduced blood flow leads to lowered oxygen and nutrients and thus the beating heart cells have insufficient energy to properly maintain function. Under these stressed conditions, cardiac myocytes ....Studies in our laboratory at the Baker Heart Research Institute over the last several years have identified a novel mechanism causing the development of arrhythmias, a primary cause of sudden cardiac death in heart failure as well as during an acute heart attack caused by acutely reduced blood flow. The reduced blood flow leads to lowered oxygen and nutrients and thus the beating heart cells have insufficient energy to properly maintain function. Under these stressed conditions, cardiac myocytes produce large amounts of a small molecule called IP3, which interferes with the normal electrical balance of the cells. Blocking IP3 generation prevents arrhythmias under these acutely ischaemic conditions. In more recent studies, we have identified many of the enzymes responsible for generation of IP3 in heart cells and have defined the properties of the regions of the cell responsible for this response. We now want to establish exactly how a period of ischaemia alters the localization or functioning of the enzymes that are responsible for this pathological change that leads to fatal arrhythmias.Read moreRead less
Single-Beat Preload Recruitable Stroke Work Measurement Of Cardiac Contractility In Three Mammalian Models.
Funder
National Health and Medical Research Council
Funding Amount
$241,980.00
Summary
The accurate measurement of the inherent pumping capacity of the heart muscle is difficult because (i) most measurements currently in use cannot accurately discriminate between the contribution of the heart muscle and that of the vascular system to the results obtained, and (ii) the measurements which can discriminate currently require invasive measurements and procedures that frequently restrict their use. The overall purpose of this proposal is to more rigorously validate a promising method we ....The accurate measurement of the inherent pumping capacity of the heart muscle is difficult because (i) most measurements currently in use cannot accurately discriminate between the contribution of the heart muscle and that of the vascular system to the results obtained, and (ii) the measurements which can discriminate currently require invasive measurements and procedures that frequently restrict their use. The overall purpose of this proposal is to more rigorously validate a promising method we have developed that will (i) make accurate assessment possible from a single cardiac beat in both experimental animals and human subjects; (ii) reduce the number of experimental animals required for such measurements by permitting sequential measurements in the same animals; (iii) make it possible to perform such measurements non-invasively in human subjects.Read moreRead less
FOXO Proteins And Protection From Cardiac Ischaemic Injury
Funder
National Health and Medical Research Council
Funding Amount
$354,375.00
Summary
Reduced blood supply to the heart can initiate a heart attack that results in damage to the heart muscle. Loss of muscle tissue under these conditions initiates pathological growth of the heart and can eventually lead to the development of heart failure, a major cause of death and disability in western countries. Treatment with growth factors can prevent the acute damage and loss of cells, but these cause detrimental effects on other tissues. For these reasons, it is necessary to establish ways ....Reduced blood supply to the heart can initiate a heart attack that results in damage to the heart muscle. Loss of muscle tissue under these conditions initiates pathological growth of the heart and can eventually lead to the development of heart failure, a major cause of death and disability in western countries. Treatment with growth factors can prevent the acute damage and loss of cells, but these cause detrimental effects on other tissues. For these reasons, it is necessary to establish ways to activate protective pathways in the heart without causing unwanted effects on other tissues. To this end, we have identified for the first time in the heart members of a newly described family of gene regulators that can cause cell death by increasing expression of cytotoxic factors. We showed that these FKHRor FOXO family members are regulated in the heart and that they are active in generating cytotoxic factors. We now plan to establish whether FOXO proteins are involved in causing cell death during heart attack and whether manipulating their activities can be cardioprotective.Read moreRead less
Regulation Of Heart Development And Regeneration By DNA Methylation.
Funder
National Health and Medical Research Council
Funding Amount
$552,709.00
Summary
The adult mammalian heart has an extremely limited capacity for regeneration following a heart attack, which is in stark contrast to the robust regenerative capacity of the newborn heart. How and why mammals lose their ability to regenerate heart tissue after birth is not well understood. We propose a new approach to unravel the complex mechanisms that control gene expression during heart development in rodents and humans, which could provide new therapeutic avenues for heart regeneration.
Development Of Non-surgical Approach To Treating Tricuspid Regurgitation
Funder
National Health and Medical Research Council
Funding Amount
$266,427.00
Summary
Heart failure is a common problem in which the heart enlarges and contracts poorly. In association with enlargement of the heart, the heart valves also begin to fail causing further worsening of quality and length of life. Failure of the tricuspid valve occurs in upto 87% of patients with heart failure and presently the only treatment option is high risk heart surgery. We are developing a way of dealing with tricuspid valve failure that does not require cardiac surgery.
This project will examine the acceptability and validity of a depression screening tool for use with Aboriginal and Torres Strait Islander patient with ischaemic heart disease, and concurrently determine depression prevalence in the sample population attending an urban Aboriginal community controlled health service.
Sympathetic Nervous System Activation In Renal Failure. Its Contribution To Pathogenesis And Progression.
Funder
National Health and Medical Research Council
Funding Amount
$490,796.00
Summary
Cardiovascular morbidity and mortality is exceedingly high in patients with chronic renal failure and particularly end stage renal disease. Recent studies suggest that sympathetic activation contributes substantially to the development of hypertension, progression of renal disease and cardiovascular prognosis in these patients. Increased sympathetic nerve firing has been demonstrated in end stage renal disease by the use of clinical microneurography, which has been attributed to uremia-related t ....Cardiovascular morbidity and mortality is exceedingly high in patients with chronic renal failure and particularly end stage renal disease. Recent studies suggest that sympathetic activation contributes substantially to the development of hypertension, progression of renal disease and cardiovascular prognosis in these patients. Increased sympathetic nerve firing has been demonstrated in end stage renal disease by the use of clinical microneurography, which has been attributed to uremia-related toxins. However, renal transplant recipients with excellent graft function and no signs of uremia still exhibit increased sympathetic nerve firing. Most interestingly, bilateral nephrectomized patients have nerve firing rates comparable to that of normal control subjects without renal disease. These data suggest that the diseased kidneys exert excitatory effects on the sympathetic nervous system independent of correction of uremia. The proposed study aims to comprehensively investigate the pattern of sympathetic activation both centrally (microneurography) and regionally (radiotracer dilution methodology) in patients with chronic renal failure and end stage renal disease . The effect of the centrally acting sympatholytic drug rilmenidine on sympathetic activity in the setting of renal disease will be assessed. Patients with ESRD waitlisted for kidney transplantation will be studied before and after transplantation. Some of the transplant recipients will also have undergone uni- or bilateral nephrectomy before transplantation which will enable us to further explore the role of the diseased kidneys in sympathetic activation. The results of this study may prove to have significant implications for treatment and prevention of cardiovascular morbid events frequently associated with renal disease.Read moreRead less