Progression of cardiovascular and endocrine dysfunction in a rabbit model of obesity

In rabbits, mean arterial pressure (MAP) increases in response to fat feeding, but does not increase further with progressive weight gain. We documented the progression of adiposity and the alterations in endocrine/cardiovascular function in response to fat feeding in rabbits, to determine whether stabilization of MAP after 3 weeks could be explained by stabilization of neurohormonal factors. Rabbits were fed a control diet or high-fat diet for 9 weeks (n¼23). Fat feeding progressively increased body mass and adiposity. Heart rate (HR) was elevated by week 3 (15±3%) but changed little thereafter. The effects of fat feeding on MAP were dependent on baseline MAP and peaked at 3 weeks. From baseline, MAP p80mmHg, MAP had increased by 8.1±1.3, 4.7±1.7 and 5.6±1.2mmHg, respectively, 3, 6 and 9 weeks after commencing the high-fat diet, but by only 2.6±1.5, 3.0±1.7 and 3.9±1.4mmHg, respectively, in control rabbits. Fat feeding did not increase MAP from a baseline 480mmHg. Plasma concentrations of leptin and insulin increased during the first 3–6 weeks of fat feeding and then stabilized (increasing by 111±17% and 731±302% by week 9, respectively), coinciding with the pattern of changes in MAP and HR. Plasma total cholesterol, triglycerides, renin activity, aldosterone and atrial natriuretic peptide were not significantly altered by fat feeding. Given that the changes in plasma leptin and insulin mirrored the changes in MAP and HR, leptin and insulin may be important factors in the development of hypertensionand tachycardia in the rabbit model of obesity.

Down the methodological rabbit hole: thinking diffractively with resistant data

This article, part of a larger study, began with an inquiry into the ways a small group of preteen boys and girls with diagnosed eating disorders discussed their ideas and attitudes about healthy bodies in individual interviews. Despite applying some of the usual analytic procedures, the data yielded little of significance in relation to body and health discourses, or to gender differences. We therefore wondered whether our underlying epistemological lenses and methodological toolkit had prevented us from seeing and hearing what was happening with this particular cohort. By shifting from a predominantly feminist post-structuralist, socio-cultural approach to one more inflected with varieties of feminist post-humanism and post-qualitative thinking, the data came differently into focus, and invited closer consideration. Employing a diffractive analysis then allowed some fresh, unexpected salience in the data to become more apparent.

Natriuretic peptides and immunoreactants modify osmoticum-dependent volume changes in Solanum tuberosum L. mesophyll cell protoplasts

In plants, as in vertebrates, natriuretic peptide (NP) hormones can influence water and solute homeostasis. Here we demonstrate that a synthetic peptide identical to the C-terminus (amino acids 99–126) of the rat atrial natriuretic peptide (rANP) modulates osmotically induced swelling of mesophyll cell protoplasts (MCPs) in a concentration and time-dependent manner. Osmotically-induced volume changes in MCPs are enhanced by plant extracts with NP immunoreactivity and this effect is concentration-dependent. In contrast, pre-treatment of the plant extracts with rabbit anti-human ANP (99–126) antiserum suppresses enhanced osmoticum-induced swelling. Isolated plant peptides (irPNP) that have been immunoaffinity purified with rabbit anti-human ANP (99–126) antiserum also enhance osmotically-induced swelling. While rANP and irPNP cause increases in cGMP levels in MCPs, elevated cGMP levels do not cause increases in osmoticum-dependent swelling but exert an inhibitory effect. These findings are consistent with a NP-dependent, cGMP-independent effect on plant cell volume regulation and a role in homeostasis for peptides that are recognized by antibodies directed against the C-terminus of vertebrate ANPs.

In situ localization associates biologically active plant natriuretic peptide immuno-analogues with conductive tissue and stomata

Plant natriuretic peptide immuno-analogues (irPNP) have previously been shown to affect a number of biological processes including stomatal guard cell movements, ion fluxes and osmoticum-dependent water transport. Tissue printing and immunofluorescent labelling techniques have been used here to study the tissue and cellular localization of irPNP in ivy (Hedera helix L.) and potato (Solanum tuberosum L.). Polyclonal antibodies active against human atrial natriuretic peptide (anti-hANP) and antibodies against irPNP from potato (anti-StPNP) were used for immunolabelling. Tissue prints revealed that immunoreactants are concentrated in vascular tissues of leaves, petioles and stems. Phloem-associated cells, xylem cells and parenchymatic xylem cells showed the strongest immunoreaction. Immunofluorescent microscopy with fluorescein isothiocyanate (FITC)-conjugated goat anti-rabbit IgG supported this finding and, furthermore, revealed strong labelling to stomatal guard cells and the adjacent apoplastic space as well. Biologically active immunoreactants were also detected in xylem exudates of a soft South African perennial forest sage (Plectranthus ciliatus E. Mey ex Benth.) thus strengthening the evidence for a systemic role of the protein. In summary, in situ cellular localization is consistent with physiological responses elicited by irPNPs reported previously and is indicative of a systemic role in plant homeostasis.

High strain mechanical loading rapidly induces tendon apoptosis : an ex vivo rat tibialis anterior model

Background: The role of apoptosis, or programmed cell death, has only recently been explored in tendon.

Objective: To investigate the development of apoptosis after high strain loading of rat tendon.

Methods: The right tibialis anterior tendons of three rats were prepared for mechanical loading, and left tendons were prepared identically as non-loaded controls. Tendon was loaded with 20% strain for six hours using a 1 Hz longitudinal sine wave signal. The following were used to assess apoptosis: (a) a monoclonal mouse antibody (F7-26) to label single stranded DNA breaks; (b) a rabbit polyclonal antibody that specifically recognises the cleaved form of caspase-3.

Results: Light microscopy confirmed that the high strain protocol induced a stretch overload injury. Control tendons showed little or no staining with the F7-26 antibody, but the loaded tendons displayed numerous apoptotic cells. The percentage of apoptotic cells (20%) in the loaded tendon was significantly greater than in the control tendon (1%) (p = 0.000). The labelled cells colocalised with abnormal nuclear morphology, including nuclear fragmentation. The staining against cleaved caspase-3 was positive in loaded tendons only, and localised both to nucleus and cytoplasm.

Conclusion: This experiment extends knowledge of human tendon apoptosis by showing that apoptosis can occur in response to short term, high strain mechanical loading. This is the first report of mechanical loading of intact tendon causing excessive apoptosis.

Towards the confirmation of the MOA model : an applied approach

The aim of this paper is to develop a grounded understanding of the role that the MOA constructs play in influencing environmentally responsible  behaviour. Data collected is used to qualitatively confirm the MOA Model (Rothschild, 1999) in an environmental management application and provide a basis to inform the development of a comprehensive quantitative causal investigation. This study will seek to determine the specific contributions of each MOA factor in the study context. The case study chosen for this investigation is representative of other social marketing applications for the MOA framework. The case study concerns the behaviour of agrarian land managers with respect to the rabbit pest problem affecting rural Australia. The paper concludes by confirming the appropriateness of the constructs within the MOA Model.

Foraging behaviour and habitat selection of the little penguin Eudyptula minor during early chick rearing in Bass Strait, Australia

Knowledge of the foraging areas of top marine predators and the factors influencing them is central to understanding how their populations respond to environmental variability. While there is a large body of literature documenting the association of air-breathing marine vertebrates with areas of high marine productivity, there is relatively little information for species restricted to near-shore or continental-shelf areas. Differences in foraging range and diving behaviour of the little penguin Eudyptula minor were examined from 3 breeding colonies (Rabbit Island, Kanowna Island and Phillip Island) in central northern Bass Strait, southeast Australia, during the chick-guard stage using electronic tags (platform terminal transmitters, PTTs, and time-depth recorders, TDRs). Although there were large overall differences between individuals, the mean maximum foraging range (16.9 to 19.8 km) and mean total distance travelled (41.8 to 48.0 km) were similar between the 3 colonies, despite different bathymetric environments. Individuals from all 3 colonies selected foraging habitats within a narrow sea surface temperature (SST) range (16.0 to 16.4°C). While there were significant differences in mean dive depths (5.4 to 10.9 m) and mean durations (13.2 to 28.6 s) between the different colonies, the mean diving effort (vertical distance travelled: 936.3 to 964.3 m h–1) was similar. These findings suggest little penguins from the 3 colonies employ relatively similar foraging efforts yet are plastic in their foraging behaviours.

Community-based environmental education : government and community, economics and environment

This thesis contends that government focus on policy implicitly defines community education as a means of overcoming barriers to government-initiated change, rather than as an input to governmental decision-making. The role of education is thus viewed as instrumentalist rather than as dialectical in nature. I argue that this role has been reinforced and driven by economic rationalism, as a mechanism related to scientific theory and practice. The thesis addresses the role of government in non-institutional community-based environmental education. Of interest is environmental education under the dominance of economic rationalism and as expressed in government-derived policy, in its own right, and as enacted in two government funded animal management projects. The main body of data, then, includes a review of some contemporary environmental policies and two case studies of 'policy in practice'. Chapter One provides an overview of environmentalism as it has emerged as part of the discourse of Western political systems. Recognised as part of this change is a move to environmentalism embued with the rhetoric of economic theory. The manifestation of this change can be seen in an emphasis on management for the natural environment's use as a resource for humans. Education under this arrangement is valued in terms of its ability to support initiatives that are perceived as economically viable and economically advantageous, maintaining centralised control of decision-making and serving the interests of those who profit from this arrangement. Government-derived environmental policies are presented in Chapter Two. They provide evidence of the conjoining of environment with economic rationalism and the adoption of a particular stance which is both utilitarian and instrumentalist. Emerging from this is an understanding of the limitations placed on environmental debates that do not respond to complex understandings of context and instead support and legitimate centralisation of decision-making and control. Chapter Three presents an argument for an historical approach to environmental education research to accommodate contextual dimensions, as well as scientific, economic and technical dimensions, of the subject under study. An historical approach to research, inclusive of biographical, intergenerational and geographical histories, goes some way to providing an understanding of current individual and collective responses to policy enactment within the two study sites. It also responds to the concealing of history which results from the reduction of environmental debates to economic terms. With this in mind, Chapters Four and Five provide two historical case studies of 'policy in practice'. Chapter Four traces the workings of a rabbit control project in the Sutton Grange district of Victoria and Chapter Five provides an account of a mouse plague project in the Wimmera and Mallee regions of Victoria. The Sutton Grange rabbit project is organised and controlled by district landholders while the Wimmera and Mallee mouse project is organised and controlled by representatives from a scientific organisation and a government agency. Considered in juxtaposition, the two case studies enable an analysis of two somewhat different expressions of the 'role of government'. Chapter Six investigates the competing processes of community participation in governmental decision-making and Australia's system of representative democracy, Despite a call for increased community participation, the majority of policies remain dominated by governmental rhetoric and ideology underpinned by a belief in impartiality. The primacy of economics is considered in terms of government and community interaction, with specific reference to the emergence of particular conceptual constructions, such as cost-benefit analysis, that support this dominance. Of specific importance to this thesis is the argument that economic theory is essentially anthropocentric and individualist and, thus, necessarily marginalises particular conceptions of environment that are non-anthropocentric and non-individualistic. Finally, Chapter Six examines two major interrelated tensions; those of central interests and community interests, and economic rationalism and environmentalist. Chapter Seven looks at examples of theories and practices that fall outside the rationality determined by scientistic knowledge. It is clear from the examination of environmental policy within this thesis that the role ascribed to environmental education is instrumentalist. The function of education is often to support, promote and implement policy and its advocated practices. It is also clear from the examination of policy and advocated processes that policy defines community education as a means of manifesting change as determined by policy, rather than as an input to governmental decision-making. The domination of scientific, economic and technocratic processes (and legitimation of processes) allows only for an instrumentalist approach to education from government. What is encouraged by government through the process of change is continuity rather than reform. It promotes change that will not disrupt the governing hegemony. Particular perspectives and practices, such as a critical approach to education, are omitted or considered only within the unquestioned rationale of the dominant worldview. Chapter Seven focuses on the consequence of government attention to policy which implicitly defines community education as a means of overcoming barriers to change, rather than as an input to governmental decision-making. Finally a list of recommendations is put forward as a starting point to reconstruct community-based environmental education. The role considered is one that responds to, and encourages engagement in, debates which expose disparate views, assumptions and positions. Community ideology must be challenged through the public practices of communication and understanding, decision-making, and action. Intervention is not on a level that encourages a preordinate outcome but, rather, what is encouraged is elaborate consideration of disparate views and rational opinions, and the exposure of assumptions and interests behind ideological positions.

Docosapentaenoic acid (22:5n-3) : a review of its biological effects

This article summarizes the current knowledge available on metabolism and the biological effects of n-3 docosapentaenoic acid (DPA). n-3 DPA has not been extensively studied because of the limited availability of the pure compound. n-3 DPA is an elongated metabolite of EPA and is an intermediary product between EPA and DHA. The literature on n-3 DPA is limited, however the available data suggests it has beneficial health effects. In vitro n-3 DPA is retro-converted back to EPA, however it does not appear to be readily metabolised to DHA. In vivo studies have shown limited conversion of n-3 DPA to DHA, mainly in liver, but in addition retro-conversion to EPA is evident in a number of tissues. n-3 DPA can be metabolised by lipoxygenase, in platelets, to form ll-hydroxy-7,9,13,16,19- and 14-hydroxy-7,10,12,16,19-DPA. It has also been reported that n-3 DPA is effective (more so than EPA and DHA) in inhibition of aggregation in platelets obtained from rabbit blood. In addition, there is evidence that n-3 DPA possesses 10-fold greater endothelial cell migration ability than EPA, which is important in wound-healing processes. An in vivo study has reported that n-3 DPA reduces the fatty acid synthase and malic enzyme activity levels in n-3 DPA-supplemented mice and these effects were stronger than the EPA-supplemented mice. Another recent in vivo study has reported that n-3 DPA may have a role in attenuating age-related decrease in spatial learning and long-term potentiation. However, more research remains to be done to further investigate the biological effects of this n-3 VLCPUFA.

Release of allergens in respirable aerosols : a link between grass pollen and asthma

Background: Asthma incidence has long been linked to pollen, even though pollen grains are too large to penetrate into the airways where asthmatic responses originate. Pollen allergens found in small, respirable particles have been implicated in a number of asthma epidemics, particularly ones following rainfall or thunderstorms.

Objective: The aim of this study was to determine how pollen allergens form the respirable aerosols necessary for triggering asthma.

Methods: Flowering grasses were humidified and then dried in a controlled-environment chamber connected to a cascade impactor and an aerosol particle counter. Particles shed from the flowers were analyzed with high-resolution microscopy and immunolabeled with rabbit anti-Phl p 1 antibody, which is specific for group 1 pollen allergens.

Results: Contrary to what has been reported in other published accounts, most of the pollen in this investigation remained on the open anthers of wind pollinated plants unless disturbed—eg, by wind. Increasing humidity caused anthers to close. After a cycle of wetting and drying followed by wind disturbance, grasses flowering within a chamber produced an aerosol of particles that were collected in a cascade impactor. These particles consisted of fragmented pollen cytoplasm in the size range 0.12 to 4.67 μm; they were loaded with group 1 allergens.

Conclusion: Here we provide the first direct observations of the release of grass pollen allergens as respirable aerosols. They can emanate directly from the flower after a moisture-drying cycle. This could explain asthmatic responses associated with grass pollination, particularly after moist weather conditions.

A further development in social marketing application of the MOA framework and behavioral implications

This social marketing study discusses the application of Rothschild’s MOA framework (Motivation, Opportunity, and Ability) in a land-use management context. The authors hypothesize that landholders with higher levels of MOA are positively associated with behavior that would result in the effective control of a vertebrate pest (the European rabbit). A random sample of 566 land managers in southeastern Australia was obtained. The development of scales associated with this study were the result of intensive qualitative research, including focus groups, in-depth interviews, and a thorough review of secondary resources. The scales were developed through a factor analytic process and were piloted and pre-tested before being used.

From the study it is ascertained that about one-third of land managers fall into the highest level of effective behavior, and for the remainder, social marketing interventions, using marketing, education, and the law, could be applied to changebehavior. The study provides evidence that Rothschild’s theoretical MOA framework can be applied to a social market and thus provides guidance on the types of interventions that may be effective in altering behavior. The MOA framework also provides a mechanism for segmentation that can be used to describe various markets and gives direction to the interventions that may be effective in altering behavior.

Balsamin, a novel ribosome-inactivating protein from the seeds of Balsam apple Momordica balsamina

Plant seeds, a rich source of proteins, are considered important for their application as functional ingredients in a food system. A novel ribosome-inactivating protein (RIP), balsamin was purified from the seeds of Balsam apple, Momordica balsamina. Balsamin was purified by ion exchange chromatography on CM Sepharose and gel filtration on superdex-75. It has a molecular weight of 28 kDa as shown by SDS-PAGE analysis. Balsamin inhibits protein synthesis in a rabbit reticulocyte lysate-based cell free translation assay with an IC50 of 90.6 ng ml⁻¹. It has RNA N-glycosidase activity and releases a 400-base long fragment termed the Endo fragment from 28S rRNA in the same manner as does saporin-6 from Saponaria officinalis. The N-terminal sequence analysis of the first 12 amino acids of balsamin revealed that it shares 83% similarity with type I RIP α-MMC from Momordica charantia and 50% similarity with β-MMC (from Momordica charantia), bryodin I (from Bryonia dioica) and luffin a (from Luffa cylindrica). Balsamin was further characterized by mass spectrometry. CD spectroscopic studies indicate that secondary structure of balsamin contains helix (23.5%), β-strand (24.6%), turn (20%) and random coil (31.9%). Thus RIPs activity expressed in vegetables like Momordica sp. advocates its usage in diet.