Identification And Characterisation Of Novel Virulence Genes In Attaching And Effacing Strains Of Escherichia Coli
Funder
National Health and Medical Research Council
Funding Amount
$281,320.00
Summary
Some varieties of Escherichia (E.) coli are harmless bacteria that live in the healthy intestinal tract, whereas others can cause diarrhoea. Those varieties of E. coli which cause diarrhoea include so-called enteropathogenic E. coli (EPEC), which is a leading cause of life- diarrhoea in infants and young children in less developed countries, and enterohaemorrhagic E. coli (EHEC) the cause of hamburger disease. These bacteria are able to cause disease because they possess specific genetic informa ....Some varieties of Escherichia (E.) coli are harmless bacteria that live in the healthy intestinal tract, whereas others can cause diarrhoea. Those varieties of E. coli which cause diarrhoea include so-called enteropathogenic E. coli (EPEC), which is a leading cause of life- diarrhoea in infants and young children in less developed countries, and enterohaemorrhagic E. coli (EHEC) the cause of hamburger disease. These bacteria are able to cause disease because they possess specific genetic information that is absent from harmless varieties of E. coli. Although many of these disease-associated genes have been identified, the specific role of many of them is not known. In addition, it seems likely that many more genes of this type remain to be discovered. The fact that EPEC is host specific means that the mechanisms by which these bacteria cause disease can only be investigated in humans. This is extremely limiting for the number and type of investigations that can be performed. However, there are rabbit-specific strains of EPEC which cause a disease in rabbits that is indistinguishable from that caused by EPEC in children. The aims of this study are to use the rabbit model of diarrhoea to learn more about the contribution of certain specific factors of EPEC to disease causation and to discover new factors of this type. This will be achieved by three complementary strategies: (1) investigating rabbit E. coli for virulence genes and determining if they are present in human strains; (2) examining the effect of inactivating these genes on the ability of E. coli to cause diarrhoea in rabbits; and (3) infecting rabbits with pools of mutant E. coli strains to identify factors that the bacteria require to survive in rabbits. The results of these studies will improve understanding of the mechanisms by which E. coli cause disease and may provide opportunities for the development of novel tools to diagnose, treat and prevent E. coli-associated diarrhoea.Read moreRead less
The Effect Of Ghrelin, Leptin And Orexins On The Function Of Pituitary Somatotropes In Rat, Mouse And Human.
Funder
National Health and Medical Research Council
Funding Amount
$447,000.00
Summary
Malnutrition such as obesity or wasting syndrome is accompanied by GH deficiency. Three newly discovered metabolic regulatory hormones, leptin from fat tissue, ghrelin from stomach and orexins from hypothalamus, play important roles in regulating appetite, energy expenditure, and adiposity. Receptors for three metabolic regulatory hormones are all present in pituitary GH secreting cells (somatotropes) and accumulated laboratory data indicate a modification of GH secretion by three hormones. Cont ....Malnutrition such as obesity or wasting syndrome is accompanied by GH deficiency. Three newly discovered metabolic regulatory hormones, leptin from fat tissue, ghrelin from stomach and orexins from hypothalamus, play important roles in regulating appetite, energy expenditure, and adiposity. Receptors for three metabolic regulatory hormones are all present in pituitary GH secreting cells (somatotropes) and accumulated laboratory data indicate a modification of GH secretion by three hormones. Contradictory results have however been reported. Mechanisms of action of these three hormones are not clear and the interrelationship between metabolic regulatory hormones and intrinsic GH regulatory system is unknown. We propose to clarify this issue by investigating the effect of in vivo treatment of mice and in vitro treatment of cultured pituitary cells with leptin, ghrelin, and orexins. GH secretion, GH and GH-regulatory hormones' receptor synthesis in pituitary somatotropes will be measured. We will also use GH-GFP transgenic mice, in which somatotropes are specifically marked with green fluorescent signal, to study morphological change of somatotropes in mouse pituitary glands after in vivo treatment. By completing this project, we will be able (1) to clarify the physiological role of metabolic regulatory hormones in control of GH levels and (2) to clarify the pathological role of metabolic regulatory hormones in GH deficiency occurred in malnutritional conditions.Read moreRead less
Structural Diversity And Evolution Of Variant-specific Surface Proteins In The Protozoan Parasite, Giardia
Funder
National Health and Medical Research Council
Funding Amount
$436,417.00
Summary
Giardia are well-known as a cause of travellers' diarrhoea, but our knowledge about these parasites remains rudimentary. Infections are common in Australia, especially in day-care centres and outback Aboriginal communities. The 1998 Sydney water crisis highlighted the necessity of monitoring reservoirs and reticulated water for contamination by faecal cysts of both human and animal origin. The aim of this project is to learn more about the 'coat' proteins which cover the organisms. These protect ....Giardia are well-known as a cause of travellers' diarrhoea, but our knowledge about these parasites remains rudimentary. Infections are common in Australia, especially in day-care centres and outback Aboriginal communities. The 1998 Sydney water crisis highlighted the necessity of monitoring reservoirs and reticulated water for contamination by faecal cysts of both human and animal origin. The aim of this project is to learn more about the 'coat' proteins which cover the organisms. These protect the parasites against digestion, enabling them to reside indefinitely within the intestine. However, the proteins are also the principal target of host immunity. Analysis of Giardia populations has shown that as many as 150-200 different coat proteins can be made. Although individual cells have coats comprised of only a single protein type, these can 'switch' spontaneously to production of another type - a phenomenon known as 'antigenic variation'. This process occurs slowly but continuously, giving rise to 'variants' which survive successive host responses (directed against each predominant coat type) and occupy the vacancies left by the destruction of their immediate forebears. It is important to gain information about the structural diversity of these variant-specific proteins (VSP), as any 'Giardia' vaccine is likely to require inclusion of each major type. It is also important to elucidate how the 'switching' process occurs, as this may provide clues as to how it might be interrupted. The project addresses both aspects.Read moreRead less
Impact Of Gastrointestinal Dysmotility On Enteral Nutrition In The Critically Ill
Funder
National Health and Medical Research Council
Funding Amount
$533,792.00
Summary
Critically ill patients require nutrition for optimum recovery. Ideally, this is provided via the gut, but oesophageal reflux, slow gastric emptying and small intestinal dysfunction frequently prevent adequate delivery of nutrients to these patients, exposing them to complications such as pneumonia and gastrointestinal bleeding. The work performed by the applicants will improve the ability of doctors in the Intensive Care Unit to feed patients and prevent the development of such complications.
Neonatal Vitamin D Status And Risk Of Schizophrenia: A Study Using Danish Dried Bloods Spots
Funder
National Health and Medical Research Council
Funding Amount
$164,980.00
Summary
There is increasing evidence that low levels of vitamin D (i.e. the 'sunshine hormone') during early development can alter brain development. In particular, it has been proposed that low vitamin D during development (e.g. prenatal and in early life), increases the risk of developing schizophrenia during adulthood. A previous study based on stored third trimester blood samples from US women suggested that very low levels of maternal vitamin D may be associated with an increased risk of schizophre ....There is increasing evidence that low levels of vitamin D (i.e. the 'sunshine hormone') during early development can alter brain development. In particular, it has been proposed that low vitamin D during development (e.g. prenatal and in early life), increases the risk of developing schizophrenia during adulthood. A previous study based on stored third trimester blood samples from US women suggested that very low levels of maternal vitamin D may be associated with an increased risk of schizophrenia in the offspring. We have the opportunity to explore this hypothesis using a large, well-described Danish 'bio-bank'. Since 1981, blood samples from newborn babies have been kept by a central agency in Denmark. In collaboration with senior Danish medical researchers, 900 blood samples of babies who have subsequently developed schizophrenia and 1800 from matched healthy individuals have been identified. We will measure vitamin D levels in these blood samples. We predict that babies with low levels of vitamin D will have an increased risk of developing schizophrenia. If low prenatal vitamin D does increase the risk of schizophrenia, this finding will have important implications from a public health perspective. Just as the number of infants affected by spina bifida has been reduced by adding folate supplements to foods, optimizing maternal vitamin D levels may lead to a reduction in the incidence of schizophrenia.Read moreRead less
The Anorexia Of Ageing: Gastrointestinal Control Of Appetite And Feeding In The Elderly
Funder
National Health and Medical Research Council
Funding Amount
$190,500.00
Summary
On current projections, the proportion of the Australian population over 65 years will double to 25% in the next 25 years. Ageing is associated with a reduction in appetite and food intake, which has been called the anorexia of ageing. After about age 70, on average, this is associated with loss of body weight, mainly of muscle. The physiological anorexia and weight loss of ageing predispose to pathological weight loss and malnutrition, which is associated with increased morbidity and death rate ....On current projections, the proportion of the Australian population over 65 years will double to 25% in the next 25 years. Ageing is associated with a reduction in appetite and food intake, which has been called the anorexia of ageing. After about age 70, on average, this is associated with loss of body weight, mainly of muscle. The physiological anorexia and weight loss of ageing predispose to pathological weight loss and malnutrition, which is associated with increased morbidity and death rates. High rates of under-malnutrition have been reported among older institutionalised people in the USA and Australia, with lesser, but still substantial, numbers of community-dwelling older people also undernourished. We found recently that 43% of 250 older recipients of domiciliary care services living in their homes in Adelaide were either malnourished or at risk of malnutrition, and had significantly worse outcomes than their well-nourished counterparts over the following year, including increased falls and hospitalisations. Little research has been done to identify underlying causes and develop treatments for this problem. Recent studies, including ours, have shown that upper gastrointestinal (GI) factors (stomach mechanics, rate of gastric emptying, GI hormones including ghrelin, cholecystokinin [CCK] and amylin) have important effects on appetite and food intake, and are often affected by ageing in ways that reduce food intake The proposed studies will investigate this upper GI control of appetite and its contribution to the anorexia of ageing. We will investigate the effects of ageing on gastric factors, including ghrelin release, the satiating effects of CCK and amylin, and the appetite stimulating effects of ghrelin. The expected outcome of this project is a greater understanding of the causes of the anorexia of ageing, enabling the logical development of effective prevention and treatment strategies.Read moreRead less
Oesophageal, Gastric And Small Intestinal Motility In Critical Illness
Funder
National Health and Medical Research Council
Funding Amount
$494,250.00
Summary
A major concern in critically ill patients is the provision of adequate nutrition to facilitate recovery from devastating insults. Abnormal contractions of the oesophagus, stomach and small intestine occur commonly in critically ill patients. These may prevent effective feeding of patients at a time when they are especially vulnerable to malnutrition and also result in major complications such as pneumonia, septicaemia and gastrointestinal haemorrhage. The applicants, with the support of the NH ....A major concern in critically ill patients is the provision of adequate nutrition to facilitate recovery from devastating insults. Abnormal contractions of the oesophagus, stomach and small intestine occur commonly in critically ill patients. These may prevent effective feeding of patients at a time when they are especially vulnerable to malnutrition and also result in major complications such as pneumonia, septicaemia and gastrointestinal haemorrhage. The applicants, with the support of the NH and MRC, have had a longstanding interest in motility disorders of the gut and have made important contributions to knowledge about both the causes and treatments of the disturbances that occur in the oesophaus, stomach and small intestine. In the previous grant (207753) these studies have provided the most comprehensive studies to date of the motor abnormalities associated with gut dysfunction in critical illness which have important implications for treatment. The applicants now seek to continue their work by investigating the mechanisms underlying these motor abnormalities and the impact of therapeutic strategies designed to enhance delivery of nutrition to critically ill patients.Read moreRead less
ProbioticTreatment Of Diarrhoeal Disease And Malnutrition In Top End Aboriginal Children
Funder
National Health and Medical Research Council
Funding Amount
$332,036.00
Summary
Aboriginal children in the Top End of Australia have high rates of hospital admission for diarrhoea and malnutrition. We have discovered that underlying small intestinal damage in these children is an important contributor to the high complication rates and longer lengths of stay in hospital compared to non-Aboriginal children. This research proposes to continue our work on small intestinal damage by using two non-invasive tests of gut function, namely a sugar absorption test and novel breath te ....Aboriginal children in the Top End of Australia have high rates of hospital admission for diarrhoea and malnutrition. We have discovered that underlying small intestinal damage in these children is an important contributor to the high complication rates and longer lengths of stay in hospital compared to non-Aboriginal children. This research proposes to continue our work on small intestinal damage by using two non-invasive tests of gut function, namely a sugar absorption test and novel breath test. The sugar permeability test involves the children drinking a solution of the two sugars lactulose and rhamnose, and measuring their absorption into the blood 90 minutes later using a sophisticated measuring instrument called HPLC, which can measure minuscule amounts of sugars and is set up at Royal Darwin Hospital. The breath test involves children drinking another sugar solution with a special non-radioactive marker called a stable isotope of carbon, and measuring changes in the amount of this marker in carbon dioxide from the breath at timed periods after drinking the sugar solution. The breath is analysed in Adelaide using another sophisticated instrument. These tests are being used to measure abnormal sugar absorption due to intestinal damage, which is particularly common in Aboriginal children during the weaning period of 4-18 months. Our hypothesis is that treatment with 'healthy germs' (probiotics) like those in certain yoghourts will colonise the gut, stimulate immunity and reduce the presence of 'nasty germs' (pathogenic bacteria) in the intestines of Aboriginal children which contribute to the need for their hospitalisation with diarrhoea and malnutrition. If this hypothesis is correct, then this research will provide the best kind of evidence for reducing the need for hospital treatment by treating all cases of diarrhoea with these probiotics and possibly even decreasing the gut damage of children in the weaning period by including probiotics in their dietsRead moreRead less