Early Retinal Vessel Changes In Diabetes And The Metabolic Syndrome
Funder
National Health and Medical Research Council
Funding Amount
$212,500.00
Summary
Diabetes mellitus affects a large proportion of adult Australians. Furthermore, many non-diabetic Australians are at high risk of developing diabetes (e.g., people with lesser glucose abnormalities, and those who are obese, have high blood pressure, or have high lipid levels). It has been suggested that diseases affecting small blood vessels (microvascular disease) in the body is closely related to the development of both diabetes and the pre-diabetes state. The current study will examine the re ....Diabetes mellitus affects a large proportion of adult Australians. Furthermore, many non-diabetic Australians are at high risk of developing diabetes (e.g., people with lesser glucose abnormalities, and those who are obese, have high blood pressure, or have high lipid levels). It has been suggested that diseases affecting small blood vessels (microvascular disease) in the body is closely related to the development of both diabetes and the pre-diabetes state. The current study will examine the relationship of microvascular disease in the retina (at the back of the eye) to diabetes, pre-diabetes status and diabetes complications. We will use a computer-imaging technique to measure the diameters of retinal blood vessel from digital photographs taken in 2,177 participants of the 1999-2000 Australian Diabetes, Obesity and Lifestyle (AusDiab) Study, a community-based survey of people aged 25 years and older examining risk factors and complications of diabetes. In the proposed study, we aim to answer the following questions: 1) Are changes in the retinal blood vessel diameter (e.g., narrowed or dilated vessels) associated with diabetes and pre-diabetes? 2) Are these retinal vessel changes related to obesity, high blood pressure and high lipid levels? 3) Are retinal vessel changes related to diabetes complications, such as heart disease, kidney disease, nerve problems and foot ulcers? 4) Do retinal vessel diameter changes predict people who will subsequently develop diabetes, irrespective of their risk factor profile? Using this well-characterized population, and existing digital retinal photographs, the proposed study will offer a unique and cost-effective opportunity to address important gaps in our understanding of how diabetes and pre-diabetes develop, and whether they are related to microvascular diseases. This may ultimately lead to new treatment and preventive approaches targeted at the small blood vessels in the body.Read moreRead less
The Physiological Role Of Calcitonin And Its Receptor In Bone Cell Metabolism.
Funder
National Health and Medical Research Council
Funding Amount
$496,446.00
Summary
Throughout adult life, bone tissue is continuously remodelled. The two main processes involved in bone remodelling, are bone formation and bone breakdown. Bone formation is controlled by cells known as osteoblasts and bone breakdown is controlled by cells known as osteoclasts. Under normal circumstances these two processes are tightly coupled. Excessive breakdown of bone, causes these two processes to become unbalanced and results in bone loss. This is the basis of many bone diseases such as ost ....Throughout adult life, bone tissue is continuously remodelled. The two main processes involved in bone remodelling, are bone formation and bone breakdown. Bone formation is controlled by cells known as osteoblasts and bone breakdown is controlled by cells known as osteoclasts. Under normal circumstances these two processes are tightly coupled. Excessive breakdown of bone, causes these two processes to become unbalanced and results in bone loss. This is the basis of many bone diseases such as osteoporosis, a condition in which the bones become fragile and therefore more susceptible to fracture. 1 in 2 women and 1 in 3 men aged 70 years and older suffer from osteoporosis in Australia. Despite this, the mechanisms which control osteoclast breakdown of bone are not well understood. Our laboratory is interested in how hormones affect osteoclast action. We plan to examine the role of the hormone calcitonin, an important inhibitor of osteoclastic bone breakdown. This will be achieved by studying transgenic mice in which the receptor, or target, for calcitonin is specifically removed from osteoclasts. This will allow us to precisely determine the role of calcitonin in osteoclast function. Data generated by our research group indicates that calcitonin is also involved in controlling bone formation, however, the way in which calcitonin acts on osteoblasts remains poorly understood. Therefore, studying our transgenic mice will also help clarify the role calcitonin plays in bone formation. Current treatment for osteoporosis involves the administration of drugs which inhibit bone breakdown. This project will increase our understanding of how calcitonin acts to regulate bone breakdown and bone formation and may assist in the design of new therapies for osteoporosis. We believe that this research is of great importance as osteoporosis is becoming more prevalent as the population ages.Read moreRead less
Factors Regulating The Temporal And Spatial Assembly Of G-protein Coupled Receptor-mediated Arrestin Complexes
Funder
National Health and Medical Research Council
Funding Amount
$472,770.00
Summary
G-protein coupled receptors are proteins that are present at the surface of most cells in the human body. They recognise and bind to specific molecules, such as hormones, the act of which results in a specific signal being transmitted into the cell. This signal alters the function of the cell and so it is critical that it is appropriate, both in type and duration. G-protein coupled receptors and the molecules that activate them provide an essential function within the human body for communicatin ....G-protein coupled receptors are proteins that are present at the surface of most cells in the human body. They recognise and bind to specific molecules, such as hormones, the act of which results in a specific signal being transmitted into the cell. This signal alters the function of the cell and so it is critical that it is appropriate, both in type and duration. G-protein coupled receptors and the molecules that activate them provide an essential function within the human body for communicating between cells, and consequently between organs. They are a major mechanism by which nerve signals are transmitted and hormones regulate bodily functions. They are therefore an important target for pharmaceuticals, with up to 50% of ethical drugs and many drugs of abuse acting upon them. It is critical to understand how these receptors alter cellular function once they receive an appropriate signal, but it is also essential to know how such responses are switched off. Arrestins are proteins within cells that interact with G-protein coupled receptors to 'arrest' their signalling. They desensitise the cell to continuous stimulation, but also act to resensitise the cell to respond to future, separate signals. Recently, they have also been shown to provide alternative mechanisms of altering cellular activity by interacting with other cellular proteins. These interactions greatly increase the potential ways in which a cell can respond once a G-protein coupled receptor is activated. Understanding the resulting complexity is essential if we are to fully exploit the vast therapeutic potential of this important receptor family.Read moreRead less
Identification Of Novel Genes Influencing Development Of Type 2 Diabetes
Funder
National Health and Medical Research Council
Funding Amount
$558,920.00
Summary
Type 2 diabetes is usually associated with obesity and is often part of a wider disturbance affecting an individual's energy metabolism. The number of affected people with type 2 diabetes has trebled since 1981 in Australia and is still increasing. Apart from individual suffering, this presents a major public health burden for the country (approx $3 billion annually). Currently available lifestyle based and pharmaceutical therapies are inadequate to control the increasing numbers of affected ind ....Type 2 diabetes is usually associated with obesity and is often part of a wider disturbance affecting an individual's energy metabolism. The number of affected people with type 2 diabetes has trebled since 1981 in Australia and is still increasing. Apart from individual suffering, this presents a major public health burden for the country (approx $3 billion annually). Currently available lifestyle based and pharmaceutical therapies are inadequate to control the increasing numbers of affected individuals. Unfortunately the cause of disease is poorly understood, although genetic factors are known to be important, in other words it runs in the family. This project proposes to identify some of these factors (genes) and how they contribute to the disease. Using molecular flags on the DNA (like DNA fingerprinting) we have previously found that a small region on chromosome 12 is likely to carry one or more of these disease genes. But there are over 100 genes in the region. To help choose the most likely candidates first for testing, we have developed an automated computer database searching program ranked the genes based on what is already known about them. We have also taken a large number of physiological measures in a large group of people. Some of these measures are controlled by the same chromosome 12 region - thus to improve our chances of finding the genes quickly we will look at those that change the most between people with diabetes and people without diabetes. In this project we shall investigate the 20 genes most likely affect diabetes based on changes in physiological measures and what is already known about them. A successful finding means we will know more about the mechanism of disease development and be able to better develop new therapies for treatment and prevention. If none of these genes are the culprit, we would continue examination of the next set of genes likely to be involved and so on until we are successful.Read moreRead less
NR1 Nuclear Hormone Receptors, And Skeletal Muscle Metabolism: Insights Into Dyslipidemia And Metabolic Disease.
Funder
National Health and Medical Research Council
Funding Amount
$582,547.00
Summary
The significance of Nuclear hormone receptors (NRs) in disease is underscored by the range of pharmacopoeia for the treatment of NR-associated disorders (e.g 16% of the top 100 drugs target NRs). Orphan NR1 receptors are abundantly expressed in skeletal muscle, a major mass peripheral tissue that accounts for ~40% of total body weight, and energy expenditure. Muscle is the major site of glucose metabolism and, fatty acid oxidation. Furthermore, it is an important regulator of cholesterol homeost ....The significance of Nuclear hormone receptors (NRs) in disease is underscored by the range of pharmacopoeia for the treatment of NR-associated disorders (e.g 16% of the top 100 drugs target NRs). Orphan NR1 receptors are abundantly expressed in skeletal muscle, a major mass peripheral tissue that accounts for ~40% of total body weight, and energy expenditure. Muscle is the major site of glucose metabolism and, fatty acid oxidation. Furthermore, it is an important regulator of cholesterol homeostasis and HDL levels. Consequently, it has a significant role in insulin sensitivity, the blood lipid profile, lipid metabolism and obesity. Understanding the functional role of the orphan NR1 receptors in skeletal muscle in the context of inflammation, lipid and energy homeostasis is of paramount importance in further understanding the mechanistic basis of dyslipidemia, chronic inflammation, insulin sensitivity, diabetes and obesity. Identification of novel NR1 targets that regulate metabolism in a major mass peripheral tissue, and positively influence the risk factors for cardiovascular disease, provides platforms for potential therapeutic intervention. Cardiovascular disease is the foremost cause of global mortality, and was responsible for >15 million deaths in 2003.Read moreRead less
The Effect Of Antiepileptic Medication On Indices Of Bone Health And Risk Factors For Falls And Fractures
Funder
National Health and Medical Research Council
Funding Amount
$469,605.00
Summary
Epilepsy is a common brain disorder and most patients with epilepsy take anti-epileptic drugs (AEDs) for many years. These patients have high rates of bone fractures, but the reasons are uncertain. Earlier studies identifying an association between AED use and bone disease were performed on institutionalised patients, and more recent studies on outpatient populations have been conflicting. A better understanding of this problem is critical for designing potential preventive measures and treatmen ....Epilepsy is a common brain disorder and most patients with epilepsy take anti-epileptic drugs (AEDs) for many years. These patients have high rates of bone fractures, but the reasons are uncertain. Earlier studies identifying an association between AED use and bone disease were performed on institutionalised patients, and more recent studies on outpatient populations have been conflicting. A better understanding of this problem is critical for designing potential preventive measures and treatments. One important additional mechanism by which AEDs may increase fracture risk is impairment of gait and balance, leading to a high risk of falls. We have novel data demonstrating the power of a Twin and Matched Sibling approach to study this important problem. This study showed that chronic AED use was associated with significant deficits in bone mineral density (BMD), a key predictor of the risk of fractures. The proposed project will ask the following questions: 1. Is BMD and estimated bone strength lower in the bones most at risk for fracture in women and men chronically taking AEDs? 2. Is the loss of bone in measurements over time greater in patients continuing to take AEDs? 3. Is the risk of bone loss greater for certain types of AEDs, and is the risk influenced by length of exposure, age and menopausal status? 4. How does AED treatment lead to reductions in BMD and bone strength? 5. Are measures of muscle strength, gait and balance impaired in patients taking AEDs compared with matched people not taking AEDs? The proposed study will utilise twins and pairs of siblings to investigate the effects of the long-term use of AEDs for epilepsy on measures of bone mass and strength, indices of bone turnover, vitamin D status, calcium regulating hormones, mineral levels, sex hormone levels, and measures of muscle strength, gait and balance function. In addition, a group of patients newly commencing AED treatment for epilepsy will be studied over 2 years.Read moreRead less
Novel Interactions Between GnRH Receptor And E2F4 Transcription Factor.
Funder
National Health and Medical Research Council
Funding Amount
$462,750.00
Summary
The reproductive endocrine system is under the control of gonadotropin-releasing hormone (GnRH), signalling via its G-protein coupled receptor (GPCR) in the anterior pituitary gland. The GnRH receptor (GnRHR) is the drug target for the treatment of a range of endocrine-related disorders as well as hormone-dependent cancers. Sustained treatment with either GnRH agonists or antagonists can block gonadotropin secretion indirectly, via down-regulation of the pituitary receptor resulting in a reducti ....The reproductive endocrine system is under the control of gonadotropin-releasing hormone (GnRH), signalling via its G-protein coupled receptor (GPCR) in the anterior pituitary gland. The GnRH receptor (GnRHR) is the drug target for the treatment of a range of endocrine-related disorders as well as hormone-dependent cancers. Sustained treatment with either GnRH agonists or antagonists can block gonadotropin secretion indirectly, via down-regulation of the pituitary receptor resulting in a reduction of gonadotropin secretion and consequent decline in steroid production. As the majority of tumours treated with GnRH analogues are hormone-dependent, this starves the tumour of the steroid support required for growth. However, the concept of a direct anti-tumour effect of GnRH, independent of the pituitary-gonadal axis, is supported by the in vitro inhibition of both cell growth and DNA synthesis in a number of tumour cell lines. Despite the wide use of GnRH analogues, the molecular basis of the growth inhibitory effects resulting from the activation of this receptor is not fully understood. Unravelling the protein interactions underlying receptor-mediated signalling events will provide valuable information towards understanding of receptor function in vivo. We have identified a novel interaction involving the GnRHR and E2F4, a transcription factor involved in suppression of the transcription of genes involved in cell cycle progression. In addition, over 80% of E2F4 knockout mice are sterile. Owing to the role of the GnRHR in the reproductive pathway we are interested in determining whether the GnRHR-E2F4 interaction has an influence on the development of the hypothalamic-pituitary-gonadal axis, hence affecting reproductive capacity. The interaction identified and studied in this proposal has implications for the treatment of reproductive tumours, such as those of the breast and prostate, and understanding the development of the hypothalamic-pituitary-gonadal axis.Read moreRead less
Proteolytic And Non-proteolytic Roles For PSA And Related Kallikrein Serine Proteases In Prostate Cancer Progression
Funder
National Health and Medical Research Council
Funding Amount
$480,128.00
Summary
Prostate cancer is the most frequently occurring cancer in men in Western countries. Prostate cancer metastasis to bone and other organs is the painful end stage of this disease. The level of prostate specific antigen (PSA) in blood is often used as a marker of prostate cancer. PSA is one of 15 related enzymes in the kallikrein family of enzymes, which may be involved in breakdown of the tissue that surrounds cells in the prostate. As prostate cancer metastasis first requires spread from the pri ....Prostate cancer is the most frequently occurring cancer in men in Western countries. Prostate cancer metastasis to bone and other organs is the painful end stage of this disease. The level of prostate specific antigen (PSA) in blood is often used as a marker of prostate cancer. PSA is one of 15 related enzymes in the kallikrein family of enzymes, which may be involved in breakdown of the tissue that surrounds cells in the prostate. As prostate cancer metastasis first requires spread from the primary tumour and out of the prostate, it is possible that high production of these kallikrein enzymes by prosttae cancer cells may increase the ability of these cells to metastasise. In previous work, we have studied prostate cancer cells that we have engineered to make the kallikreins, PSA and kallikrein 4. Those cells that make PSA or kallikrein 4 are more elongated in shape and are better able to move across a porous barrier. Another important change is that these cells stop producing a protein that is usually found on the surface of these cells and is important for helping cells to stay attached to each other. When this protein is lost, these tumour cells no longer stay attached to each other and are more likely to move out of the prostate and spread into other parts of the body. The changes we observed in the cells that produce PSA and kallikrein 4 are typical of these more aggressive cancer cells. In this project, we will look at how PSA and kallikrein 4 cause the cells to undergo these changes. The majority of prostate cancer deaths arise from cancer that has spread from the primary tumour and out of the prostate capsule. This project aims to further understand the causes of prostate cancer spread and metastasis. This is a vital research priority if we are to address the mortality associated with prostate cancer metastasis and may lead to new treatment approaches for advanced metastic prostate cancer.Read moreRead less
Breast Cancer has a particular preference to form cancer metastases in bone where its presence is associated with bone destruction that frequently results in significant pain and disability. Bone seems to provide a fertile soil for breast cancer cells that have moved into the blood vessels from the original cancer site in the breast. Once tumour cells have invade bone marrow spaces from the blood vessels they are able to grow and induce the normal cells of the bone marrow to destroy the surround ....Breast Cancer has a particular preference to form cancer metastases in bone where its presence is associated with bone destruction that frequently results in significant pain and disability. Bone seems to provide a fertile soil for breast cancer cells that have moved into the blood vessels from the original cancer site in the breast. Once tumour cells have invade bone marrow spaces from the blood vessels they are able to grow and induce the normal cells of the bone marrow to destroy the surrounding hard bone. This allows the tumour to grow faster. Together these processed create a vicious cycle that contributes to the serious consequences of bone metastases. In this project we will be studying mice with breast cancer to understand what makes the bone marrow such a fertile and receptive site for breast cancer metastasis. In particular, we are looking at how the normal processes of bone renewal and repair contribute to the establishment of cancer in bone. We will use the body's own bone protecting protein, called osteoprotegerin, to test how blocking bone destruction will affect the ability of cancer cells to invade and grow in bone. This study has the potential to change the way bone metastases are treated. Treatment of breast cancer could be significantly improved if the fertile soil of bone could be modified to either block the targeting of breast cancer to bone, or to inhibit its growth there.Read moreRead less