Periostin as a biomarker of airway inflammation

No abstract available

Environmental Conditions and Vegetation Recovery at Abandoned Drilling Mud Sumps in the Mackenzie Delta Region, Northwest Territories, Canada

Historical data from oil and gas exploration in the delta of the Mackenzie River, Northwest Territories, in the 1970s provided an opportunity to estimate decadal-scale impacts of exploratory oil and gas drilling on native plant communities in low Arctic tundra. We assessed changes in vegetation composition and associated environmental gradients across seven drilling mud sumps in the Kendall Island Bird Sanctuary, Mackenzie Delta. Three decades after disturbance, drilling sumps had developed vegetation coverage equivalent to that in undisturbed areas, although bare soil persisted in ponded areas and where a salt crust was present. Vegetation on sumps was composed of communities dominated by forbs, grasses, and tall shrubs that were distinct from adjacent, undisturbed sedge and low shrub communities. The area of altered vegetation around a sump was generally larger in upland or saline environments than in lowland areas. Pooled water observed around many sumps was likely associated with thaw subsidence that occurred following construction, which was subsequently compounded by snow drifting and increased soil temperatures along the margins of the sump mound. Changes in drainage, active-layer depth, and surface salt concentrations appear to be key environmental factors that have helped shape plant communities established on drilling sumps in the three decades after disturbance.Les données historiques relatives à l’exploration pétrolière et gazière réalisée dans le delta du fleuve Mackenzie, Territoires du Nord-Ouest, dans les années 1970 ont permis d’estimer les incidences décadaires des forages pétroliers et gaziers exploratoires sur les peuplements de végétaux régionaux de la basse toundra arctique. Nous avons évalué les changements caractérisant la composition de la végétation et les gradients environnementaux connexes relativement à sept bassins à boue du refuge d’oiseaux de l’île Kendall, dans le delta du Mackenzie. Trois décennies après la perturbation, la couverture végétale des bassins à boue était équivalente à celle des endroits non perturbés, bien qu’il restait toujours du sol dénudé dans les endroits en présence d’étangs et de croûtes salées. Le végétation se retrouvant sur les bassins était composée d’herbes non graminéennes, de graminées et de grands arbrisseaux différents des peuplements adjacents constitués de laiche et de petits arbrisseaux non perturbés. La zone caractérisée par la nouvelle végétation autour d’un bassin était généralement plus volumineuse dans les hautes terres ou les milieux salins que dans les basses terres. L’eau accumulée autour de nombreux bassins découlait vraisemblablement de la subsidence attribuable au dégel qui s’est manifesté après la construction, ce qui a été aggravé par la poudrerie et les températures du sol à la hausse le long des marges du monticule des bassins. Les changements en matière de ruissellement, de profondeur de la couche active et de concentrations de sel de surface semblent constituer d’importants facteurs environnementaux ayant aidé à façonner les peuplements de végétaux qui se sont établis sur les bassins de forage au cours des trois décennies ayant suivi la perturbation

A comparative study of the biological and molecular properties of mesenchymal stem cells isolated from bone marrow and the olfactory system

Neurodegenerative conditions such as Multiple Sclerosis (MS) and spinal cord injury (SCI) affect hundreds of thousands of people each year worldwide, and numerous cell transplant-based therapeutic strategies are being investigated to aid in the repair and regeneration of the central nervous system. Of particular interest are mesenchymal stem cells (MSCs), due to their differentiation potential, their immunomodulatory effects, and their ability to stimulate various biological properties due to the substantial variety of growth factors, chemokines, and other signalling molecules secreted by these cells. MSCs taken from the bone marrow (BM-MSCs) have demonstrated significant reparative potential in animal models of both MS and SCI. The question I address throughout this thesis however, is whether MSCs from another niche; the olfactory mucosa (OM-MSCs), are a preferable or at least alternative candidate for such therapies, compared to BM-MSCs, and if they are, why are they? Previous studies have shown that OM-MSCs can be purified and grown from human olfactory mucosa and when incubated with rat glial/neuronal co-cultures are capable of increasing axonal myelination, an effect not elicited by BM-MSCs. This potentially has great therapeutic benefit for a range of neurodegenerative conditions, as a significant part of the regenerative process involves replacing the protective myelin membrane which ensheaths axons. A comparative study of the two types of MSCs shows a number of similarities, including the expression of the same panel of MSC markers, a 64% homology in miRNA expression, an ability to differentiate towards bone and fat, and a propensity for bone formation when cultured on osteogenic nanotographies. This thesis also outlines a number of differences between each phenotype which suggest that OM-MSCs could even be a preferred alternative, especially in neuroregenerative therapies. OM-MSCs were shown to express significantly more Nestin than BM-MSCs, and to proliferate at a significantly higher rate, two observations which may be related. This increased proliferation would have enormous benefit for their use, as BM-MSCs are mitotically quite slow, and any MSC-based therapies would require very large numbers of cells. Twenty six different miRNA were shown to be differentially expressed between BM-MSCs and OM-MSCs. Three of these; miR-140-5p, miR-146a-5p, and miR-335-5p were linked to three important biological functions; myelination, cell survival, and cell proliferation respectively. These three biological functions, importantly, are ones which were observed as being behavioural differences between OM-MSCs and BM-MSCs. OM-MSCs were also shown to secrete significantly more of the pro-myelinating chemokine, CXCL12, which was confirmed as being regulated by the microRNA, miR-140-5p. This offered a potential mechanism for the pro-myelinating effect of OM-MSCs, and also opens up new research potential for investigating therapeutic targets to regulate myelination. The data presented in this thesis shows many similarities between BM-MSCs and OM-MSCs, but it also highlights some profound differences which suggest that either they originate from a different lineage entirely, or that the cellular niche that they reside in does indeed affect the differentiation and behaviour of mesenchymal stem cells

The Use of Radioactive Marker as a Tool to Evaluate the Drug Release in Plasma and Particle Biodistribution of Block Copolymer Nanoparticles

Diblock copolymer nanoparticles encapsulating a paclitaxel prodrug, Propac 7, have been used to demonstrate the usefulness of a nonmetabolizable radioactive marker, cholesteryl hexadecyl ether (CHE), to evaluate nanoparticle formulation variables. Since CHE did not exchange out of the nanoparticles, the rate of clearance of the CHE could be used as an indicator of nanoparticle stability in vivo. We simultaneously monitored prodrug circulation and carrier circulation in the plasma and the retention of CHE relative to the retention of prodrug in the plasma was used to distinguish prodrug release from nanoparticle plasma clearance. Nanoparticles labelled with CHE were also used to evaluate accumulation of nanoparticles in the tumour. This marker has provided relevant data which we have applied to optimise our nanoparticle formulations

Combined cognitive and state-control training for children with and without AD/HD: Effects on behaviour, working memory and resting EEG

Abstract presented at the 23rd Australasian Society for Psychophysiology Conference, 20-22 Nov 2013, Wollongong, Australi

Prognosis of West Nile virus associated acute flaccid paralysis: a case series

Introduction: Little is known about the long-term health related quality of life outcomes in patients with West Nile virus associated acute flaccid paralysis. We describe the quality of life scores of seven patients with acute flaccid paralysis who presented to hospital between 2003 and 2006, and were followed for up to two years. Case presentations: Between 2003 and 2006, 157 symptomatic patients with West Nile virus were enrolled in a longitudinal cohort study of West Nile virus in Canada. Seven patients (4%) had acute flaccid paralysis. The firs

What is the most efficient and effective method for long-term monitoring of alpine tundra vegetation?

Nondestructive estimations of plant community characteristics are essential to vegetation monitoring programs. However, there is no universally accepted method for this purpose in the Arctic, partly because not all programs share the same logistical constraints and monitoring goals. Our aim was to determine the most efficient and effective method for long-term monitoring of alpine tundra vegetation. To achieve this, we established 12 vegetation-monitoring plots on a south-facing slope in the alpine tundra of southern Yukon Territory, Canada. Four observers assessed these plots for vascular plant species abundance employing three methods: visual cover (VC) and subplot frequency (SF) estimation and modified point-intercept (PI) (includes rare species present but not intersected by a pin). SF performed best in terms of time required per plot and sensitivity to variations in species richness. All methods were similarly poor at estimating relative abundance for rare species, but PI and VC were substantially better at high abundances. Differences among methods were larger than among observers. Our results suggest that SF is best when the monitoring focus is on rare species or species richness across extensive areas. However, when the focus is on monitoring changes in relative abundance of common species, VC or PI should be preferred

Quantifying a systems map: network analysis of a childhood obesity causal loop diagram

Causal loop diagrams developed by groups capture a shared understanding of complex problems and provide a visual tool to guide interventions. This paper explores the application of network analytic methods as a new way to gain quantitative insight into the structure of an obesity causal loop diagram to inform intervention design. Identification of the structural features of causal loop diagrams is likely to provide new insights into the emergent properties of complex systems and analysing central drivers has the potential to identify leverage points. The results found the structure of the obesity causal loop diagram to resemble commonly observed empirical networks known for efficient spread of information. Known drivers of obesity were found to be the most central variables along with others unique to obesity prevention in the community. While causal loop diagrams are often specific to single communities, the analytic methods provide means to contrast and compare multiple causal loop diagrams for complex problems

Spitzer Observations of the HII Region NGC 2467: An Analysis of Triggered Star Formation

We present new Spitzer Space Telescope observations of the region NGC 2467, and use these observations to determine how the environment of an HII region affects the process of star formation. Our observations comprise IRAC (3.6, 4.5, 5.8, and 8.0 um) and MIPS (24 um) maps of the region, covering approximately 400 square arcminutes. The images show a region of ionized gas pushing out into the surrounding molecular cloud, powered by an O6V star and two clusters of massive stars in the region. We have identified as candidate Young Stellar Objects (YSOs) 45 sources in NGC 2467 with infrared excesses in at least two mid-infrared colors. We have constructed color-color diagrams of these sources and have quantified their spatial distribution within the region. We find that the YSOs are not randomly distributed in NGC 2467; rather, over 75% of the sources are distributed at the edge of the HII region, along ionization fronts driven by the nearby massive stars. The high fraction of YSOs in NGC 2467 that are found in proximity to gas that has been compressed by ionization fronts supports the hypothesis that a significant fraction of the star formation in NGC 2467 is triggered by the massive stars and the expansion of the HII region. At the current rate of star formation, we estimate at least 25-50% of the total population of YSOs formed by this process.Comment: Accepted to the Astrophysical Journal, set to appear in Volume 701; 18 pages, 13 figures, 4 tables. This version reflects a few major changes made in the accepted version, including new figure

On three-dimensional misorientation spaces.

Determining the local orientation of crystals in engineering and geological materials has become routine with the advent of modern crystallographic mapping techniques. These techniques enable many thousands of orientation measurements to be made, directing attention towards how such orientation data are best studied. Here, we provide a guide to the visualization of misorientation data in three-dimensional vector spaces, reduced by crystal symmetry, to reveal crystallographic orientation relationships. Domains for all point group symmetries are presented and an analysis methodology is developed and applied to identify crystallographic relationships, indicated by clusters in the misorientation space, in examples from materials science and geology. This analysis aids the determination of active deformation mechanisms and evaluation of cluster centres and spread enables more accurate description of transformation processes supporting arguments regarding provenance