Dynamic Measures of Arterial Stiffness in a Rodent Model

Cardiovascular disease is one of the leading causes of death in Canada. Arterial stiffness is an important factor in the pathogenesis of cardiovascular disease. Cardiac failure, hypertension, renal failure, and dementia have all been linked to arterial stiffness. The arterial system is designed to dampen the pulses of blood from the heart's left ventricle and distribute the blood forward as steady flow in the small vessels. The pulse-dampening ability of the arterial system is reduced with age when the elastic fibers in the arterial wall degrade and fracture. The arterial stiffening process can accelerate from deposition of minerals within the arterial wall, such as calcium, from the endothelial layer becoming compromised or from fibrosis secondary to inflammation or turbulence. Arterial stiffness can be assessed post-mortem by microscopic examination of the arterial wall. However, for use in dynamic experiments and for therapeutic intervention, several ante-mortem techniques have been developed: pulse wave velocity (PWV), pulse waveform analysis (PWA), wave separation analysis (WSA), and carotid ultrasonography. Rats are important models for cardiovascular disease, toxicology, and pharmacological studies because of their convenient size and short life cycle. However, PWA and WSA have not been shown to be valid approaches for studying arterial stiffness in rat peripheral arteries. In this thesis, dynamic in vivo methods for PWA and WSA in rat peripheral arteries were developed to provide accurate measures of arterial stiffness. Software specific to the rat vasculature, PWanalyze and WSanalyze, was developed to measure PWA and WSA parameters, respectively. A comparison of these PWA and WSA methods in rat peripheral arteries was performed by creating a range of arterial stiffnesses through acute and chronic experiments. Arterial stiffness was measured in the femoral artery by a novel PWA parameter, the minimum time derivative of blood pressure dp/dt(min), as effectively as the established parameter the maximum time derivative of blood pressure dp/dt(max). A new method of WSA in femoral arteries was developed. Backward wave amplitude measured in the aorta was shown to increase as arteries stiffened and decrease as arteries relaxed with acute vasoactive drug injections. These experiments showed that dp/dt(min) and WSA are valid approaches to use when studying arterial stiffness in rats

Combined dielectrophoretic and impedance system for on-chip controlled bacteria concentration: Application to Escherichia coli

The present paper reports a bacteria autonomous controlled concentrator prototype with a user-friendly interface for bench-top applications. It is based on a micro-fluidic lab-on-a-chip and its associated custom instrumentation, which consists in a dielectrophoretic actuator, to pre-concentrate the sample, and an impedance analyser, to measure concentrated bacteria levels. The system is composed by a single micro-fluidic chamber with interdigitated electrodes and a instrumentation with custom electronics. The prototype is supported by a real-time platform connected to a remote computer, which automatically controls the system and displays impedance data used to monitor the status of bacteria accumulation on-chip. The system automates the whole concentrating operation. Performance has been studied for controlled volumes of Escherichia coli (E. coli) samples injected into the micro-fluidic chip at constant flow rate of 10 μL/min. A media conductivity correcting protocol has been developed, as the preliminary results showed distortion of the impedance analyser measurement produced by bacterial media conductivity variations through time. With the correcting protocol, the measured impedance values were related to the quantity of bacteria concentrated with a correlation of 0.988 and a coefficient of variation of 3.1%. Feasibility of E. coli on-chip automated concentration, using the miniaturized system, has been demonstrated. Furthermore, the impedance monitoring protocol had been adjusted and optimized, to handle changes in the electrical properties of the bacteria media over time

EFSA Panel on Biological Hazards (BIOHAZ); Scientific Opinion on VTEC-seropathotype and scientific criteria regarding pathogenicity assessment

During 2007-2010, 13 545 confirmed human VTEC infections and 777 haemolytic uraemic syndrome (HUS) cases were reported in the EU; isolates from 85 % of cases were not fully serotyped and therefore could not be classified using the Karmali seropathotype concept. Seropathotype group D covered 5 % of isolates from fully serotyped cases; 14 cases (0.7 %) belonged to seropathotype group E, defined by Karmali et al. (2003) as non-human only. Isolates from around 27 % of cases could not be assigned. There were no HUS cases reported for the serotypes in groups D and E but 17 HUS cases could not be assigned. The health outcome was reported for only a fraction of confirmed cases. About 64 % of patients presented with only diarrhoea; VTEC infection resulted in HUS in around 10 % of cases. The new ISO/TS 13136:2012 standard improves the detection of VTEC in food. An alternative concept based on the detection of verocytotoxins alone or genes encoding such verocytotoxins does not provide a sound scientific basis on which to assess risk to the consumer because there is no single or combination of marker(s) that fully define a ‘pathogenic’ VTEC. Strains positive for verocytotoxin 2 gene(vtx2)- and eae (intimin production)- or [aaiC (secreted protein of EAEC) plus aggR (plasmid-encoded regulator)] genes are associated with higher risk of more severe illness than other virulence gene combinations. The 2011 O104:H4 outbreak demonstrated the difficulty of predicting the emergence of ‘new’ pathogenic VTEC types by screening only for the eae gene or by focusing on a restricted panel of serogroups. A molecular approach utilising genes encoding virulence characteristics additional to the presence of vtx genes has been proposed

Climate-sensitive health priorities in Nunatsiavut, Canada

Background: This exploratory study used participatory methods to identify, characterize, and rank climate-sensitive health priorities in Nunatsiavut, Labrador, Canada. Methods: A mixed method study design was used and involved collecting both qualitative and quantitative data at regional, community, and individual levels. In-depth interviews with regional health representatives were conducted throughout Nunatsiavut (n = 11). In addition, three PhotoVoice workshops were held with Rigolet community members (n = 11), where participants took photos of areas, items, or concepts that expressed how climate change is impacting their health. The workshop groups shared their photographs, discussed the stories and messages behind them, and then grouped photos into re-occurring themes. Two community surveys were administered in Rigolet to capture data on observed climatic and environmental changes in the area, and perceived impacts on health, wellbeing, and lifestyles (n = 187). Results: Climate-sensitive health pathways were described in terms of inter-relationships between environmental and social determinants of Inuit health. The climate-sensitive health priorities for the region included food security, water security, mental health and wellbeing, new hazards and safety concerns, and health services and delivery. Conclusions: The results highlight several climate-sensitive health priorities that are specific to the Nunatsiavut region, and suggest approaching health research and adaptation planning from an EcoHealth perspective