A genomic approach to understanding the cause and effect of annual ryegrass toxicity

Annual Ryegrass Toxicity (ARGT) is a potentially lethal disease affecting livestock grazing on pastures or consuming fodder that include annual ryegrass (Lolium rigidum) contaminated with corynetoxins. The corynetoxins (CTs), among the most lethal toxins produced in nature, are produced by the bacterium Rathayibacter toxicus that uses a nematode vector to attach to and infect the seedheads of L.rigidum. There is little known of the factors that control toxin production. Several studies have speculated that a bacteriophage specific to R.toxicus may be implicated in CT production. We have developed a PCR-based assay to test for both bacterium and phage in ryegrass material and results indicate that there is a correlation between phage and bacterial presence in all toxic ryegrass samples tested so far. This PCR-based technique may ultimately allow for a rapid, high-throughput screening assay to identify potentially toxic pastures and feed in the field. Currently, ~80% of the 45 Kb genome has been sequenced an investigation to further elucidate its potential role in toxin production.Furthermore, specific alterations in gene expression as a result of exposure to CTs or the closely related tunicamycins (TMs), which are commercially available and considered biologically indistinguishable from CTs, will be evaluated for use as biomarkers of exposure. The effects of both toxins will be analysed in vitro using a rat hepatocyte cell line and screened on a low-density DNA micro array “CT-Chip” that contains <100 selected rat hepatic genes. The results are expected to further define the bioequivalence of CTs and TMs and to identify levels of exposure that are related to specific toxic effects or have no adverse effect on livestock.

Nutrition, management and other environmental influences on the quality and production of mohair and cashmere with particular reference to mediterranean and annual temperate climatic zones : a review

Goat fibre production is affected by genetic and environmental influences. Environmental influences which are the subject of this review include bio–geophysical factors (photoperiod, climate–herbage system and soil–plant trace nutrient composition), nutrition factors and management factors. Nutrition and management influences discussed include rate of stocking, supplementary feeding of energy and protein, liveweight change, parturition and management during shearing. While experimental data suggest affects of seasonal photoperiod on the growth of mohair and cashmere are large, these results may have confounded changes in temperature with photoperiod. The nutritional variation within and among years is the most important climatic factor influencing mohair and cashmere production and quality. Mohair quality and growth is affected significantly by rate of stocking and during periods of liveweight loss by supplementary feeding of either energy or protein. Strategic use of supplements, methods for rapid introduction of cereal grains, influence of dietary roughage on intake and the economics of supplementary feeding are discussed. Cashmere production of young, low producing goats does not appear to be affected by energy supplementation, but large responses to energy supplementation have been measured in more productive cashmere goat strains. The designs of these cashmere nutrition experiments are reviewed. Evidence for the hypothesis that energy-deprived cashmere goats divert nutrients preferentially to cashmere growth is reviewed. The influence and potential use of liveweight manipulation in affecting mohair and cashmere production and quality are described. Estimates of the energy requirements for the maintenance of fibre goats and the effect of pregnancy and lactation on mohair and cashmere growth are summarised. The effects and importance of management and hygiene during fibre harvesting (shearing) in producing quality fibre is emphasised. The review concludes that it is important to assess the results of scientific experiments for the total environmental content within which they were conducted. The review supports the view that scientific experiments should use control treatments appropriate to the environment under study as well as having controls relevant for other environments. In mediterranean and annual temperate environments, appropriate controls are liveweight loss and liveweight maintenance treatments. Mohair producers must graze goats at moderate rates of stocking to maximise animal welfare, but in so doing, they will produce heavier goats and coarser mohair. In mediterranean and annual temperate environments, seasonal changes in liveweight are large and influence both quality and production of mohair and cashmere. Mohair and cashmere producers can manipulate liveweight by supplementary feeding energy during dry seasons to minimise liveweight loss, but the economics of such feeding needs to be carefully examined. Strategic benefits can be obtained by enhancing the growth of young does prior to mating and for higher producing cashmere goats.

The medical provision of hydration and nutrition: Two very different outcomes in Victoria and Florida

Decisions to withhold or withdraw medical hydration and nutrition are amongst the most difficult that confront patients and their families, medical
and other health professionals all over the world. This article discusses two cases relating to lawful withdrawal and withholding of a percutaneous endoscopic gastrostomy tube (PEG) from incompetent patients with no hope of recovery. Victoria and Florida have statutory frameworks that provide for advance directives, however in both Gardner; Re BWV and Schindler v Schiavo; Re Scliiavo the respective patients did not leave documented instructions. The article analyses the two cases and their outcomes from legal, medical and ethical perspectives.

The effect of exercise and nutrition on the mechanostat

In this review, we discuss the effect of increased and decreased loading and nutrition deficiency on muscle and bone mass and strength (and bone length and architecture) independently and combined. Both exercise and nutrition are integral components of the mechanostat model but both have distinctly different roles. Mechanical strain imparted by muscle action is responsible for the development of the external size and shape of the bone and subsequently the bone strength. In contrast, immobilization during growth results in reduced growth in bone length and a loss of bone strength due to large losses in bone mass (a result of endosteal resorption in cortical bone and trabecular thinning) and changes in geometry (bone shafts do not develop their characteristic shape but rather develop a rounded default shape). The use of surrogate measures for peak muscle forces acting on bone (muscle strength, size, or mass) limits our ability to confirm a cause-and-effect relationship between peak muscle force acting on bone and changes in bone strength. However, the examples presented in this review support the notion that under adequate nutrition, exercise has the potential to increase peak muscle forces acting on bone and thus can lead to a proportional increase in bone strength. In contrast, nutrition alone does not influence muscle or bone in a dose-dependent manner. Muscle and bone are only influenced when there is nutritional deficiency – and in this case the effect is profound. Similar to immobilization, the immediate effect of malnutrition is a reduction in longitudinal growth. More specifically, protein and energy malnutrition results in massive bone loss due to endosteal resorption in cortical bone and trabecular thinning. Unlike loading however, there is indirect evidence that severe malnutrition when associated with menstrual dysfunction can shift the mechanostat set point upward, thus leading to less bone accrual for a given amount of bone strain.

Development and application of polymerase chain reaction-based assays for Rathayibacter Toxicus and a Bacteriophage associated with annual ryegrass (Lolium Rigidum) toxicity

Annual ryegrass toxicity (ARGT) is responsible for significant stock losses in South Australia and Western Australia. The toxicity is caused by corynetoxins produced by the bacterium Rathayibacter toxicus (with the possible involvement of a bacteriophage), which infects annual ryegrass (Lolium rigidum). Polymerase chain reaction (PCR)-based assays, compatible with an existing enzyme-linked immunosorbent assay for the corynetoxins, have been developed and used to screen L. rigidum for both the presence of R. toxicus and for the bacteriophage isolate NCPPB 3778. The results from analysing bacterially infected galls from toxic grain screenings showed a positive correlation between the presence of the bacterium and corynetoxins but not with the bacteriophage. Analysis of pasture-derived samples of annual ryegrass showed about a 50% correlation of corynetoxins with bacterial presence and about a 5% correlation of phage with the presence of the bacterium. These observations support the potential application of the PCR-based assays in providing a useful, complementary tool in the assessment of the likelihood of pasture and feed to cause ARGT and to enable a better understanding of the complex aetiology of ARGT.

Analysing health claims policy in Australia : a case study of evidence in food and nutrition policy-making

Purpose: Health claims generally describe an association between a food product and a health outcome. There is debate whether health claims promote or obstruct healthy food selection behaviour. This study investigates the role of evidence in food and nutrition policy-making. The research question is how and why was health claims policy made in Australia? The research is innovative in its critical analysis design and its focus on building theory to help improve food and nutrition policy-making processes and outcomes.

Methods: A case study design was adopted in which events, stakeholders and issues associated with the policy review were described from data generated from interviews and documentary sources. A content-analysis tool is being used to critically analyse textual data. Concepts in the text are being identified and relationships among the policy concepts, stakeholders and processes are being mapped.

Findings: The analysis of data associated with the policy review is revealing a pattern of relationships among stakeholders, processes and concepts around shared values, beliefs and interests towards food and health. Broader food regulation contexts have influenced the decision-making environment. The pattern of relationships shares common characteristics with Sabatier’s ‘Advocacy Coalition Framework’ theoretical explanation of policy-making.

Conclusions: The study findings have implications for health claims policy and practice in Australia. As a case study of evidence in food and nutrition policy-making, this research highlights the role of competing interests, beliefs and values in evidence interpretation. Challenges are identified in undertaking food policy research.

Critical evaluation of cashmere nutrition experiments and suggestions for the design and conduct of successful experiments

Cashmere fibre production is an order of magnitude less than fibre production of Merino sheep or Angora goats and is more difficult to measure. Based on a comparison between cashmere experiments reporting responses to nutrition and those reporting no response, 13 design and management characteristics were identified that are related to the ability of experiments to discriminate among treatments. Methods must be adopted to reduce the variance in cashmere production within treatments, by using sufficient. animals per treatment, having enough replication to provide plenty of degrees of freedom to reduce error terms in analysis, and using pre-experimental cashmere production attributes as co-variants in analysis. It is preferable to use more productive and older goats, and goats that are used to handling, and to the conditions and feed to be used. Nutrition treatments need to produce different live weight growth curves and an appropriate control is needed such as live weight maintenance. As the raw cashmere fleece is composed primarily of hair and other contaminants, careful attention is required to measure, sample and test cashmere. Cashmere growth experiments should start by midsummer and last for at least four and preferably six months. These requirements make it more difficult for many university students to plan, undertake and complete long-term cashmere nutrition experiments without considerable management support.

Nutrition therapy in the prevention and treatment of pressure ulcers

Pressure ulcers are serious problems within hospital and aged care settings and are associated with adverse health outcomes and high treatment costs. Because of a high incidence of pressure ulcers in the health system, attention is now being directed to not just preventing, but also more effectively treating them. Nutrition plays a fundamental part in wound healing, with malnutrition, dehydration and recent weight loss identified as independent risk factors for the development of pressure ulcers. While the optimal nutrient intake to promote wound healing is unknown, increased needs for energy, protein, zinc and vitamins A, C and E have been documented. There is reasonable evidence to show that nutritional support, mostly by high-protein oral nutritional supplements, is effective in significantly reducing the incidence of pressure ulcers in at-risk patients by 25%. Intervention studies using high-protein or specialised disease-specific nutritional supplements support a trend to increased healing of established pressure ulcers. Such specialised supplements are typically based on defined amounts of arginine, vitamin C and zinc. Mechanisms by which nutritional support can aid in pressure ulcer prevention and healing are likely related to addressing macro- and/or micro-nutrient deficiencies arising from either poor oral intake or increased nutrient requirements related to the wound healing process. With much more research still to be done in this area, nutrition support appears an efficacious and costeffective adjunct to current medical and nursing approaches in the prevention and treatment of pressure ulcers.

Annual variation in the distribution of summer snowdrifts in the Kosciuszko alpine area, Australia, and its effect on the composition and structure of alpine vegetation

Australian alpine ecosystems are expected to diminish in extent as global warming intensifies. Alpine vegetation patterns are influenced by the duration of snow cover including the presence of snowdrifts in summer, but there is little quantitative information on landscape-scale relationships between vegetation patterns and the frequency of occurrence of persistent summer snowdrifts in the Australian alps. We mapped annual changes in summer snowdrifts in the Kosciuszko alpine region, Australia, from Landsat TM images and modelled the frequency of occurrence of persistent summer snowdrifts from long-term records (1954–2003) of winter snow depth. We then compared vegetation composition and structure among four classes that differed in the frequency of occurrence of persistent summer snowdrifts. We found a curvilinear relationship between annual winter snow depth and the area occupied by persistent snowdrifts in the following summer (r²=0.9756). Only 21 ha (0.42% of study area) was predicted to have supported summer snowdrifts in 80% of the past 50 years, while 440 ha supported persistent summer snow in 10% of years. Mean cover and species richness of vascular plants declined significantly, and species composition varied significantly, as the frequency of summer snow persistence increased. Cushion plants and rushes were most abundant where summer snowdrifts occurred most frequently, and shrubs, grasses and sedges were most abundant in areas that did not support snowdrifts in summer. The results demonstrate strong regional relationships between vegetation composition and structure and the frequency of occurrence of persistent summer snowdrifts. Reductions in winter snow depth due to global warming are expected to lead to substantial reductions in the extent of persistent summer snowdrifts. As a consequence, shrubs, grasses and sedges are predicted to expand at the expense of cushion plants and rushes, reducing landscape vegetation diversity. Fortunately, few vascular plant species (e.g. Ranunculus niphophilus) appear to be totally restricted to areas where summer snow occurs most frequently. The results from this study highlight potential indicator species that could be monitored to assess the effects of global warming on Australian alpine environments.

Prevalence, awareness, treatment, and control of hypertension in China data from the China National Nutrition and Health Survey 2002

Background— The present article aims to provide accurate estimates of the prevalence, awareness, treatment, and control of hypertension in adults in China.

Methods and Results— Data were obtained from sphygmomanometer measurements and an administered questionnaire from 141 892 Chinese adults 18 years of age who participated in the 2002 China National Nutrition and Health Survey. In 2002, 153 million Chinese adults were hypertensive. The prevalence was higher among men than women (20% versus 17%; P<0.001) and was higher in successive age groups. Overall, the prevalence of hypertension was higher in urban compared with rural areas in men (23% versus 18%; P<0.01) and women (18% versus 16%; P<0.001). Of the 24% affected individuals who were aware of their condition, 78% were treated and 19% were adequately controlled. Despite evidence to suggest improved levels of treatment in individuals with hypertension over the past decade, compared with estimates from 1991, the ratio of controlled to treated hypertension has remained largely unchanged at 1:4.

Conclusions— One in 6 Chinese adults is hypertensive, but only one quarter are aware of their condition. Despite increased rates of blood pressure–lowering treatment, few have their hypertension effectively controlled. National hypertension programs must focus on improving awareness in the wider community, as well as treatment and control, to prevent many tens of thousands of cardiovascular-related deaths.