Determining The Cellular Mechanisms Involved In The Airway Response To Topical Citrate
Funder
National Health and Medical Research Council
Funding Amount
$444,491.00
Summary
The air passages of the lungs are lined by mucous membranes. These membranes are covered by a thin layer of fluid to protect the airways from drying. This fluid allows the cilia, the hair like projections on top of the airway cells to beat more effectively to remove mucous and inhaled particles from the lungs. The volume and composition of this fluid is determined by the salt and water movement across the mucous membranes of the airways. These processes are abnormal in cystic fibrosis (CF), the ....The air passages of the lungs are lined by mucous membranes. These membranes are covered by a thin layer of fluid to protect the airways from drying. This fluid allows the cilia, the hair like projections on top of the airway cells to beat more effectively to remove mucous and inhaled particles from the lungs. The volume and composition of this fluid is determined by the salt and water movement across the mucous membranes of the airways. These processes are abnormal in cystic fibrosis (CF), the most common lethal inherited disease affecting Australians. In CF, an abnormal gene disrupts one of the major mechanisms for salt and water movement in the air passages. This abnormal salt transport causes drying of the airway surface which impairs the working of the cilia. This leads to retention of mucous in the airways with repeated bacterial infections damaging the lungs. Over the last 10 years, we have developed a series of simple tests to measure the abnormalities in the CF airway of human subjects. We have isolated an exciting new clinical application for sodium citrate, a substance used in blood transfusions. Citrate appears to alter both the salt transport abnormalities found in CF. This research proposal seeks to better understand the dual effects of citrate and to test similar compounds that may have stronger effects. The ultimate aim of our research is to have sufficient knowledge to work out the best way to develop a new treatment for CF.Read moreRead less
Molecular Determinants Of Inhibitory Synaptic Function Studied Using Mutant And Transgenic Mice
Funder
National Health and Medical Research Council
Funding Amount
$496,500.00
Summary
Communication between nerve cells is the key to effective brain function and when disturbed, pathological states such as epilepsy, schizophrenia, fear and anxiety, spasticity and motor disorders ensue. This project is based on new data which suggests that the site of this communication, called the synapse, is a much more dynamic structure than previously thought. Based on our work to date, where we have demonstrated the recruitment of selected classes of neurotransmitter receptors into synapses, ....Communication between nerve cells is the key to effective brain function and when disturbed, pathological states such as epilepsy, schizophrenia, fear and anxiety, spasticity and motor disorders ensue. This project is based on new data which suggests that the site of this communication, called the synapse, is a much more dynamic structure than previously thought. Based on our work to date, where we have demonstrated the recruitment of selected classes of neurotransmitter receptors into synapses, our aim is to use a range of naturally occuring mice mutants, as well as transgenic mice to modulate the receptor levels and so to examine the role of synaptic function and synaptic dynamics. The outcomes of this project will provide fundamental new knnowledge aimed at understanding how communication in the nervous system works and may suggest ways in which modulation of this information flow could be used to treat disorders of brain function.Read moreRead less
Identification And Function Of Kv7-M-channels In Axons Of Cortical Neurons
Funder
National Health and Medical Research Council
Funding Amount
$324,930.00
Summary
Membrane proteins permeable to potassium ions provide an important break during hyperexcitability of nerve cells in the brain. In this proposal I will study the function of a unique member of potassium channel protein (the M-channel) located at key regions of nerve cells; the axon. The results will provide important insights into the elementary steps of nerve cell excitability, and a better understanding of M-channel related diseases including neonatal epilepsies and chronic nerve pain.
The Role Of Mechanoelectric Feedback In Cardiac Arrhythmogenesis
Funder
National Health and Medical Research Council
Funding Amount
$307,550.00
Summary
Arrhythmias are disruptions of the normal electrical rhythm of the heart, and can vary from asymptomatic to fatal. It used to be thought that the electrical and mechanical functions of the heart muscle were essentially separate: the electrical activity triggered contraction something like pulling the trigger of a gun- once events were in motion, the electrical events played no further role. However, in recent years it has become apparent that this is an over-simplification of the real situation. ....Arrhythmias are disruptions of the normal electrical rhythm of the heart, and can vary from asymptomatic to fatal. It used to be thought that the electrical and mechanical functions of the heart muscle were essentially separate: the electrical activity triggered contraction something like pulling the trigger of a gun- once events were in motion, the electrical events played no further role. However, in recent years it has become apparent that this is an over-simplification of the real situation. In fact, the electrical activity of the heart is influenced strongly by the degree and timing of stretch to which the heart muscle is subjected, a process called Mechano-electric feedback. Since it can be demonstrated in isolated tissues, mechano-electric feedback must be an intrinsic property of the heart muscle. It has been shown in isolated heart preparations that passive stretch produces electrical disturbances in the normal action potential shape and propagation and that these electrical disturbances can be powerful enough to generate severe arrhythmias. There are paralells in human diseases. For example, atrial arrhythmias are common in older people, and it seems that these may be due to chronic stretch of the atria, as a consequence of high blood pressure. In addition, in those patients recovering from a heart attack, it seems likely that the damaged part of the heart muscle subjects the surrounding tissue to unusual mechanical stresses, and may trigger arrhythmias. This project aims to investigate the mechanisms underlying this mechano-electric feedback, in an attempt to understand some types of arrhythmias. Using molecular biology techniques, we will look at the gene expression of a novel type of stretch-activated potassium channel in both healthy and diseased animal hearts, with the aim of seeing if changes in the level of expression of these channels is correlated with changes in the response of the heart to stretch.Read moreRead less
How Does Oxygen Regulate Ca2+ Channel Function In Cardiac Myocytes?
Funder
National Health and Medical Research Council
Funding Amount
$475,517.00
Summary
Oxygen occupies a key role in cellular metabolism and function. Oxygen delivery to cells is critical and lack of oxygen such as occurs during a heart attack can be lethal. Death occurs commonly by induction of arrhythmia or a disturbance in the heart beat. The abnormal heart beat cannot enable the heart to pump blood efficiently and vital organs are then deprived.Exactly how arrhythmia is induced is not understood. The normal heart beat occurs as a result of propogation of electrical signals thr ....Oxygen occupies a key role in cellular metabolism and function. Oxygen delivery to cells is critical and lack of oxygen such as occurs during a heart attack can be lethal. Death occurs commonly by induction of arrhythmia or a disturbance in the heart beat. The abnormal heart beat cannot enable the heart to pump blood efficiently and vital organs are then deprived.Exactly how arrhythmia is induced is not understood. The normal heart beat occurs as a result of propogation of electrical signals through heart muscle cells. The electrical activity is generated and sustained by movement of salts or ions through membrane proteins known as ion channels. One of these channels, the L-type calcium channel plays a vital role in cardiac excitation and contraction. A reduction in oxygen alters the function of the L-type calcium channel. However, the exact mechanism for this is uncertain. An oxygen sensing mechanism in the cell is responsible for the regulation of channel function during hypoxia. The exact identity of the oxygen sensor is currently the centre of debate. Four hypotheses have been proposed. This proposal aims to examine in detail the four hypotheses of oxygen sensing to definitively determine the identity of the oxygen sensor. This information should increase our understanding of how calcium channels function during stressful conditions such as during a heart attack.Read moreRead less
I am a molecular electrophysiologist determining structure function relationships in cardiac ion channels and investigating the role of ion channel mutations in the pathogenesis of inherited arrhythmia syndromes
A Novel Patch-fluorimetry Technique For Investigating Structural Changes During Gating Of Mechanosensitive Ion Channnels
Funder
National Health and Medical Research Council
Funding Amount
$387,018.00
Summary
Membrane proteins, especially membrane channels play an important role in regulating the flow of substances across the cell. Dysfunction in these channels can lead to a variety of diseases. Thus approximately 60% of drug development is targeted against such proteins. In our research, we are looking at membrane channels found in bacteria. Understanding the function of these channels will help us develop novel anti-bacterial agents. It will also aid to understand a role of ion channels in disease.
Computational Study Of Selectivity, Gating And Mutation In The Acetylcholine Receptor And Potassium Channels
Funder
National Health and Medical Research Council
Funding Amount
$301,393.00
Summary
One way cells in living organisms communicate with each other is via the passage of charged particles across the cell membrane. This takes place through ion channels, large protein molecules that span the membrane and allow small molecules or ions to pass through a central pore. Malfunction of ion channels is known to underlie a variety of disorders including epilepsy, hypertension, kidney disease, heart attack, deafness. Channels also provide promising targets for making new broad spectrum anti ....One way cells in living organisms communicate with each other is via the passage of charged particles across the cell membrane. This takes place through ion channels, large protein molecules that span the membrane and allow small molecules or ions to pass through a central pore. Malfunction of ion channels is known to underlie a variety of disorders including epilepsy, hypertension, kidney disease, heart attack, deafness. Channels also provide promising targets for making new broad spectrum antibiotics and antivirals. This project aims to study two important types of ion channel: acetylcholine receptors that convey signals between nerve and muscle cells, and potassium channels that regulate the nerve impulses themselves. The binding of the neurotransmitter acetylcholine released from a nerve cell to acetylcholine receptors in the muscle cell prompts the opening of a cation conductive pore. The resulting influx of ions initiates a cascade of events ending in the contraction of the muscle fibre. However, the way in which this channel opening is initiated and how ions move into the muscle cell remain to be determined. Potassium channels are primarily used to rapidly 'switch off' nerve impulses so that subsequent messages can be passed through the nerve cell. To do this they have to be highly discriminatory, allowing only potassium to pass across the cell membrane and not sodium that would initiate another impulse. Although we now know what these tiny proteins look like, it is not clear how they differentiate between types of ions while still allowing many millions to pass each second. We will use computer simulations to study how these two type of channel open and close, and how they discriminate between different ion types. Using sophisticated computational techniques on Australia's most powerful supercomputers we aim to elucidate this fundamental area of human biology in the hope of deriving treatments for some debilitating neuromuscular diseases.Read moreRead less
Identification Of Novel Therapeutic Binding Sites On Glycine Receptors By High Throughput Screening
Funder
National Health and Medical Research Council
Funding Amount
$542,017.00
Summary
Glycine receptors mediate inhibitory neurotransmission in the nervous system. They provide fresh therapeutic targets for chronic inflammatory pain and muscle spasticity. Here we identify 5 compounds that may be appropriate as leads for discovering novel therapies for these disorders. We will use automated high throughput screening methods to discover how these drugs interact with the receptor. This will narrow down the search for the next generation of analgesic and muscle relaxant drugs.