We will seek to address an important clinical problem in orthpaedics, namely the bone loss that commonly occurs around joint replacement prostheses. Termed peri-prosthetic osteolysis (PO), this bone loss can result in the loosening and ultimate failure and need for revision of the artificial joint components. PO is thought to be caused by the body's reaction to wear particles generated from the articulating surface of the prosthesis. However, it has not previously been possible to accurately exp ....We will seek to address an important clinical problem in orthpaedics, namely the bone loss that commonly occurs around joint replacement prostheses. Termed peri-prosthetic osteolysis (PO), this bone loss can result in the loosening and ultimate failure and need for revision of the artificial joint components. PO is thought to be caused by the body's reaction to wear particles generated from the articulating surface of the prosthesis. However, it has not previously been possible to accurately explore the relationship between prothesis wear and PO, or the progression of PO, because of a lack of techniques to image and measure the volume of PO around metal prosthesis components. We have developed a means to accurately and reproducibly measure the volume of bone loss, using CT, and will do so longitudinally in joint replacement patients to obtain the first information about the progression of PO. New computer based methods will be used concurrently to relate prosthesis wear and migration parameters to PO. Patients who come to surgery for replacement of failed prostheses will be investigated further by analysis of the tissues involved in the bone loss around prostheses. Basic science experiments will seek to understand the underlying causes of PO and the findings will be important in interpreting the clinical results. An animal model will be used to seek approaches to inhibiting the pathological response to wear particles. The significance of these studies is that they will lead to improved outcomes for joint replacement patients, increasing the interval to revision surgery, which is both extremely costly and brings an attendant morbidity and mortality.Read moreRead less
GENETIC PREDICTION OF FRACTURE IN A RISK-STRATIFIED POPULATION
Funder
National Health and Medical Research Council
Funding Amount
$363,000.00
Summary
Osteoporosis is a condition characterised by excessive bone loss and impaired bone quality, which ultimately results in fracture with minimal trauma. Osteoporosis affects 27% of women and 11% of men aged 60 years or above in the community, and costs Australia around $7 billion each year. Individuals with low bone mineral density (BMD) have a significantly higher risk of fracture than those with normal BMD. In the long-term (14-year) Dubbo Osteoporosis Epidemiology Study, more than half of indivi ....Osteoporosis is a condition characterised by excessive bone loss and impaired bone quality, which ultimately results in fracture with minimal trauma. Osteoporosis affects 27% of women and 11% of men aged 60 years or above in the community, and costs Australia around $7 billion each year. Individuals with low bone mineral density (BMD) have a significantly higher risk of fracture than those with normal BMD. In the long-term (14-year) Dubbo Osteoporosis Epidemiology Study, more than half of individuals with osteoporosis (e.g., low BMD) did not sustain a fracture, while approximately 60% of fracture cases had BMD above the high risk levels. Thus, BMD alone is not a good discriminant of fracture versus non-fracture cases. It is widely known that the liability to fracture is determined in part by genes. Previous studies, including from our group, have suggested a number of candidate genes that are associated with fracture risk. The fundamental issue that this study is concerned is that how and whether genetic markers could be used to facilitate case finding. It is proposed that common variations of certain genes are associated with fracture risk independent of BMD. That is, they can identify individuals at relatively high and low fracture risk after stratification for BMD. Hence, some markers may identify those individuals likely (and unlikely) to fracture even with low (osteoporotic) BMD. Similarly, some, possibly the same, markers may identify individuals at high risk of fracture despite relatively good (ie non-osteoporotic) BMD. It is further proposed that no single gene will achieve this outcome, but rather a small set of such gene polymorphisms will provide clinically useful risk information. This effect is entirely analogous to the use of clinical risk indicators (eg, age, weight, sex, family history, etc) to assess the risk of future fracture.Read moreRead less
The Risks And Benefits Of Contemporary Total Hip Replacement
Funder
National Health and Medical Research Council
Funding Amount
$493,530.00
Summary
The number of hip replacements undertaken in Australia is steadily increasing. The most common complications of hip replacements are dislocation and loosening due to bone loss around the implant, requiring complex and expensive revision surgery. This study will investigate the incidence of dislocation and, using a new diagnostic imaging technique, the incidence and amount of bone loss around a relatively new prosthetic material, the outcomes of which are not known despite its increasing use.
Functional Effects Of Polymorphic Variation Of The Aromatase (CYP19) Gene On Enzyme Activity:relationship To Disease
Funder
National Health and Medical Research Council
Funding Amount
$237,708.00
Summary
After menopause, oestrogen synthesis changes from an ovarian to an adipose source by concersion of androgens to estrogens, a process catalyzed by aromatase, the product of the CYP19 gene. We will generate mutants of the CYP19 gene that we have previously found in humans by site-directed mutagenesis and observe the effects of these mutants on aromatase function. This research will help with diagnosis and treatment of breast and other cancers and osteoporosis in humans .
This proposal is designed to test the protein leverage hypothesis (PLH) in humans: the idea that the level of food consumption in humans, like other animals, is adjusted to maintain a target protein intake. As the prevalence of overweight and obesity increases, with its attendant health problems, the need to identify which dietary components limit rather than exacerbate energy intake is imperative. According to the PLH, the consumption of a diet low in % protein and high in % fat and carbohydrat ....This proposal is designed to test the protein leverage hypothesis (PLH) in humans: the idea that the level of food consumption in humans, like other animals, is adjusted to maintain a target protein intake. As the prevalence of overweight and obesity increases, with its attendant health problems, the need to identify which dietary components limit rather than exacerbate energy intake is imperative. According to the PLH, the consumption of a diet low in % protein and high in % fat and carbohydrate, typical of many Western countries, inevitably requires the ingestion of additional energy to maintain protein intake constant, thus driving weight gain. Conversely, the consumption of a diet that is relatively high in % protein requires the ingestion of lower levels of energy, creating the potential for weight loss. Preliminary experimental and population-level nutritional survey data support the PLH, as does the finding that protein is more satiating than other macronutrients. If, as predicted, small changes in the proportion of protein in diets described in the current study are found to impact on total energy intake there will be significant implications for weight control strategies. Thus, if the PLH is confirmed, public health dietary recommendations and government policy settings for the food industry will need to change. Large-scale intervention studies aimed at demonstrating the longer term impact on body weight will also be required.Read moreRead less
Population Outcomes And Cost-effectiveness Of Universal Newborn Hearing Vs Risk Factor Screening At Age 5 Years.
Funder
National Health and Medical Research Council
Funding Amount
$540,423.00
Summary
Universal newborn hearing screening (UNHS) is being widely implemented because it is thought to greatly improve outcomes for children with congenital deafness. However, it is also very costly. Between 2003-5, all New South Wales babies were offered UNHS, while Victorian babies were offered a risk-factor screening and referral program. This two-year 'natural experiment' paves the way for a unique population effectiveness and cost-effectiveness study of UNHS as the children reach 5 years of age.
TELEPHONE COUNSELLING FOR MAINTENANCE OF PHYSICAL ACTIVITY, WEIGHT LOSS And GLYCAEMIC CONTROL IN TYPE 2 DIABETES
Funder
National Health and Medical Research Council
Funding Amount
$1,285,894.00
Summary
Regular exercise, a healthy diet and weight loss are key to managing type 2 diabetes, yet these are major challenges for most people with diabetes. This study will evaluate the impact of a telephone counselling program to assist people with type 2 diabetes to exercise, eat a healthy diet and lose weight, with the goal of helping them to sustain these changes over the long-term. It is expected that these lifestyle changes will also result in improved blood glucose control and quality of life.
Determination Of Irradiation Dose Efficacy For Use In Impaction Grafting At Revision Joint Replacement
Funder
National Health and Medical Research Council
Funding Amount
$411,517.00
Summary
Primary hip replacement is a successful intervention for hip disease, but 10-15% of hip prostheses fail and require revision surgery within 10-15 years. At the time of revision, significant bone loss around the failed prosthesis is not uncommon. A bone reconstruction procedure, called impaction grafting, where donor bone is minced and placed in the areas of deficient bone before implanting the new prosthesis, has shown to give good results at more than ten years in some centres. A high incidence ....Primary hip replacement is a successful intervention for hip disease, but 10-15% of hip prostheses fail and require revision surgery within 10-15 years. At the time of revision, significant bone loss around the failed prosthesis is not uncommon. A bone reconstruction procedure, called impaction grafting, where donor bone is minced and placed in the areas of deficient bone before implanting the new prosthesis, has shown to give good results at more than ten years in some centres. A high incidence of early complications of this procedure have included loss of fixation within the bone. Fracture of the bone around prostheses has also reported in some centres. These events require more surgery, putting the patient at higher risk greater complications and longer rehabilitations. Recent improvements in surgical technique and donor bone preparation have improved results. A current debate questions whether the dose of irradiation can be reduced from 25 kGy, while maintaining sterility of allografts. The risk of bacterial contamination in allografts is low, and irradiation reduces the mechanical strength of the graft, contributing to complications when irradiated bone is used. The benefits of decontaminating the bone may be outweighed by the higher risk for failure due to poor bone quality and resulting prosthesis instability. We will use ISO standards to test the validity of radiation dose for sterilising bone ex vivo. In the absence of controlled human studies, our aim is also to compare the results of impaction grafting with non-irradiated bone versus bone irradiated at current doses used by Australian bone banks, and lower doses indicated by ex vivo testing. We will use a large animal model of revision hip replacement, with precise measures of prosthesis stability. The results of this study will guide clinical decisions regarding the efficacy of current bone graft preparation procedures and the use of irradiated bone in human hip replacement surgery.Read moreRead less
Effects Of The Fatty Acid, Lauric Acid, On Energy Intake And Gut Motor And Hormonal Function In Health And Obesity
Funder
National Health and Medical Research Council
Funding Amount
$744,645.00
Summary
Obesity is largely due to energy intake exceeding energy expenditure, thus, strategies that reduce energy intake will result in weight loss. We discovered recently that the fatty acid, lauric acid, markedly reduces energy intake. Our studies will determine the effects of lauric acid on energy intake and body weight reduction in obese subjects. The research is a new initiative and explores the potential of lauric acid as a novel, nutrient-based and side-effect free approach to obesity management.
LIM KINASE 1 (LIMK1) AND METASTASIS, THE SEARCH FOR LIMK1 INHIBITORS
Funder
National Health and Medical Research Council
Funding Amount
$461,250.00
Summary
Disseminated cancer, unlike the localized disease, can rarely be cured by drug therapy. We have found that LIM kinase (LIMK1), a protein that was discovered in our laboratory, plays an important role in controlling the ability of tumour cells to spread, a process called metastasis. Thus, this protein becomes an important target for the development of new drug therapies to prevent the spread of cancer. Importantly, we have demonstrated that (1) inhibiting LIMK1 blocks the formation of metastatic ....Disseminated cancer, unlike the localized disease, can rarely be cured by drug therapy. We have found that LIM kinase (LIMK1), a protein that was discovered in our laboratory, plays an important role in controlling the ability of tumour cells to spread, a process called metastasis. Thus, this protein becomes an important target for the development of new drug therapies to prevent the spread of cancer. Importantly, we have demonstrated that (1) inhibiting LIMK1 blocks the formation of metastatic tumours in mice, and (2) introduction of this protein into tumour cells makes them more invasive. In addition, we find that the level of LIMK1 is much higher in human tumour cell lines that have the propensity to easily form tumours in mice. Also, measuring the level of this protein in cancer cells that spread to other organs shows that it is at significantly elevated levels when compared to normal tissue. The goals of this research are to: (1) understand whether the ability of LIMK1 to regulate tumour spreading and invasiveness correlates with its ability to control metastasis; (2) examine in human tumour samples whether the levels of LIMK1 correlate with the development of metastatic tumours; and (3) search for drugs that can inhibit the activity of this protein. The results from this research will be highly significant because LIMK1 levels are likely to be an important marker for which tumours will become metastatic. It is possible that, at the time of tumour diagnosis, LIMK1 measurements will enable the clinician to predict whether an individual tumour will become metastatic. Secondly, this protein is a novel drug development target. Drugs that inhibit this protein may block the ability of tumours to invade and metastasise.Read moreRead less