Jagals, P., Prof. du Preez, H.H., Prof.

Dans les écosystèmes aquatiques, l'activité anthropique, mais aussi le contexte naturel induisent chez les organismes aquatiques des situations de stress multiples. Parmi les sources potentielles de perturbation, trois d'entre elles, d’origine chimique, ont été étudiées : contamination métallique, une contamination par un herbicide, par un mélange d’alkylphénols polyéthoxylés et enfin une contamination par un produit pétrolier. Cette démarche entre dans le cadre de la directive européenne REACh (Registration Evaluation Autorisation of CHemicals) mais aussi de la directive cadre eau DCE (directive 2000/60/CE) du parlement Européen et du Conseil établissant une politique communautaire dans le domaine de l'eau. Il s’agit en fait d'évaluer la pertinence d’une série d’indicateurs précoces de pollution (ex : biomarqueurs) afin de prédire l'effet des substances chimiques lors de contaminations chroniques ou ponctuelles du milieu aquatique. Une approche intégrée des interactions des substances ou produits sélectionnés sur la réponse génétique, protéique, cellulaire, histologique et individuelle chez la truite arc-en-ciel, Onchorynchus mykiss, a été entreprise en mésocosmes ouverts et dynamiques et en laboratoire. In vivo, une étude multimarqueurs sur des truites juvéniles femelles diploïdes a été menée à chaque exposition, de 21 ou 28 jours, et durant une période de « récupération » afin d'estimer les effets sur la physiologie des truitelles. Le mélange de nonylphénols polyéthoxylés et l’essence utilisés pour les expositions montrent ainsi des effets qui perdurent jusqu’à la fin de cette période de « récupération ». Les mésocosmes, utilisés lors de cette thèse, offrent des conditions favorables au maintien et à la croissance de truites juvéniles. (...) Dans une démarche de recherche de biomarqueurs d’effets chez une espèce modèle, transposer ces travaux chez des poissons (mâles et femelles) à des stades de développement différents pourrait ainsi permettre d’isoler les paramètres les plus pertinents, à chaque stade ou pour l’ensemble du cycle de l’espèce, afin d’apporter de nouveaux outils pour la surveillance des milieux aquatiques. / In the aquatic ecosystems, anthropic activity, but also natural environment induce several kind of stress in aquatic organisms. Among the potential sources of stress, three chemicals were studied here: a metal, a bipyridylium herbicide, a mixture of nonylphenol polyethoxylate and an oil product exposure. This study enters within the framework of the European directive REACh (Registration Evaluation Authorization of CHemicals) but also of the Directive Cadre Eau, DCE (directive 2000/60/CE) of the European Parliament. The aim is to evaluate the relevance of an early pollution indicator pool (biomarkers) in order to predict chemical substance effects during chronic exposure or after specific contaminations of the aquatic compartment. An integrated approach of the substance effects on the genetic, proteinic, cellular, histological and individual answers in the rainbow trout, Onchorynchus mykiss, were undertaken in open and dynamic mesocosms and also laboratory. In vivo, a multibiomarker study on female juvenile trout was done at each exposure, over 21 or 28 days, followed by a period of “recovery». The mixture of nonylphenol polyethoxylate and the gasoline used for the exposures thus show effects which perdurent until the end of this period of “recovery. The mesocosms used in this study offer favorable conditions for juvenile survival and growth. (...) In addition to the assessment of the measurement robustness and the biomarker relevance, we compared the data obtained in this study with the in vivo tests and those obtained using in vitro tests. This approach made possible to highlight coherent answers between in vitro the tests and in vivo markers. But in vitro tests are only one preliminary approach to quickly seek a specific toxic action. The modulation monitoring of key genes in the fish reproduction function, during a gasoline exposure, offers complementary informationabout the pollutant mode of action. We noted that the effects of the contamination on the hormonal rates were differed in time compared to the modulation of the gene transcription. In order to bring new tools for the monitoring, in a model species, of the aquatic environment,transposing this work in male and female fish at different developmental stages would enableisolating still most relevant parameters.

MSc, Physiotherapy, Faculty of Health Sciences, University of the Witwatersrand / Background: Jet nebulisers are one of the primary devices used in the nebulisation of ventilated patients. It has been observed that due to cost restraints devices marked as “single use” are inadvertently being used as “single-patient-use” devices. This has both ethical and medico legal implications for the ICU. Ventilator-associated pneumonia (VAP) in limited-resource countries carries a large burden of increased mortality, morbidity and cost. Ineffective or absent nebuliser decontamination in ventilated patients can increase the risk of the development of VAP as well as the risk of antibiotic resistance. Objectives: The aim of this study was to examine the current practice of nebuliser decontamination and the incidence of contamination of nebulisers after use within a ventilator circuit, in ICUs in Johannesburg, South Africa. The secondary objectives of the study were to assess the presence of and adherence to a decontamination protocol in intensive care units (ICU) in Johannesburg and to identify which practices were associated with lower or no bacterial growth. Methods: A cross-sectional study design was used which included an interview with the unit manager and an audit of current nebuliser practice in the ICU. Nebulisers that were identified in the interview were then swabbed and streaked on blood agar plates (BAPs). Blood agar plates were then incubated and assessed for bacterial colonisation, number of colony forming units (CFUs) and number of different species of CFUs that were formed. Results: Single-use jet nebulisers represented 93% of nebulisers used within a ventilator circuit. All of the single-use jet nebulisers were being re-used (n=42). None of the hospitals studied had a nebuliser decontamination protocol. The contamination rate for jet nebulisers that had been re-used within the ventilator circuit was 52%. In the group of nebulisers that had bacterial colonisation, the nebulisers that were stored in a sterile drape had a significantly higher concentration of bacterial growth, than those that were not stored in a sterile drape (p=0.03). Nebulisers are often used in the administration of bronchodilators in ICUs in Johannesburg, South Africa. Colonised nebulisers can create bacterial aerosol when used within a ventilator circuit. A change to single-patient-use devices, such as vibrating mesh nebulisers, may assist in reducing the problem of colonisation of jet nebulisers. Conclusion: The rate of colonisation of jet nebulisers that have been re-used is unacceptably high. ICUs need to develop nebuliser decontamination protocols. Physiotherapists should assist with creating awareness and driving the creation of these protocols. ICUs should be encouraged to change single-use devices to single-patient-use devices. Nebulisers should not be stored in sterile drapes after use in a ventilator circuit.

"Characterizing the effects of subsurface wastewater effluent discharges remains as a significant challenge impacting both ground-water and surface water resources. Important aspects of this challenge relate to the quantification of the main processes affecting oxygen consumption within a wastewater plume and to the ability of representing these conditions over a range of scales. The goal of this research is to improve our understanding of the relevant processes affecting oxygen consumption and thus, controlling natural attenuation in wastewater contaminated aquifers, and also to characterize and quantify these processes through modeling approaches considering different scales. The analysis included consideration of restoration processes associated with a former sewage disposal discharge in Falmouth, MA. The discharge was removed in 1995, and the site has been experiencing natural restoration since removal. A small-scale natural gradient tracer test, completed 6 years after cessation of sewage disposal, was used in previous research to develop parameters to characterize aerobic respiration and nitrification processes, key oxygen consuming processes for this site. In addition, field monitoring by the United States Geological Survey has provided a series of concentration profiles at different locations along the flowpath associated with the contaminant source. For this research, predictions obtained with the existing model were used in conjunction with these concentration profiles to assess the sensitivity and applicability in the parameters from this small-scale test, as well as their pertinence to the larger scale restoration process. By evaluating the applicability of this model to different scales and the associated variability of key model parameters, the approach provided an improved characterization of the primary processes affecting oxygen consumption."

This dissertation combines field data, laboratory experiments, and mathematic models to (1) predict the probability of groundwater arsenic (As) contamination caused by geogenic sources and processes in shallow aquifers of the Mississippi Delta in southern Louisiana, (2) study the role microbes play in controlling As mobilization from sediments to groundwaters, and (3) simulate As mobilization and transport caused by changing redox conditions and groundwater geochemistry along a flow path within the southeastern Chicot aquifer in southern Louisiana. A model based on surface hydrology, soil properties, geology, and sedimentary deposition environments predicts that the Holocene shallow aquifers in southern Louisiana are at high risk of As contamination. Sediment incubation and pore-water chemistry suggest that microbes play a key role in mobilizing As from sediments by reductive dissolution of As-bearing Fe(III) oxides/oxyhydroxides. Finally, groundwater samples were collected along a 10 km flow path in the southeastern Chicot aquifer to determine groundwater geochemical parameters and to simulate reactive transport of Fe and As species along the studied flow path. The model well captures the general trends of Fe(II) and As(III) concentrations along the studied flow path and the close correspondence between Fe(II) and As(III) of the both measured and model predicted As(III) and Fe(II) concentrations support the hypothesis that microbially mediated reductive dissolution of As-bearing Fe(III) oxides/oxyhydroxides is the primary mechanism causing As mobilization from sediments to the shallow reducing groundwaters of the Mississippi Delta in southern Louisiana. / 1 / NINGFANG YANG

Because Mexican foods have been implicated in a number of outbreaks of foodborne illness in the United States, production procedures used in Mexican restaurants were investigated by interviewing four managers. Two major problems identified through these interviews were failure to cool large quantities of beans rapidly and failure to reheat beans thoroughly before placement on the steam table. Experiments were designed to study the effects of varying temperatures, duration of incubation, and the location in the product as it might affect aeration on growth of B. cereus and C. perfringens, singly and combined, in cooked mashed pinto beans. Growth of both B. cereus and C. perfringens was rapid at 37°C, with numbers of cells associated with illness reached in 4 and 6 hours, respectively. B. cereus may present more of a health hazard, since obvious signs of spoilage did not occur in these beans until 12 hours, whereas C. perfringens caused obvious spoilage of beans within 6 to 8 hours. At 23°C with B. cereus, the numbers associated with illness were found at 12 hours. However, the beans appeared to be spoiled before this level was reached with C. perfringens at 24 hours. Aeration, as indicated by location in the jar, appeared to have more of an effect on B. cereus growth than on C. perfringens, but good growth of the two species occurred in both top and bottom locations. Restaurant samples of bean dip and mashed beans were analyzed for contamination with B. cereus and C. perfringens. Total aerobic and anaerobic counts were determined. Only two of the 42 samples were found to contain B. cereus or C. perfringens and these were present in low numbers. The total aerobic and anaerobic counts varied from less than 100 to 100,000,000 per gram: chiefly lactic acid bacteria which appeared to be related to the seasoning ingredients. However, one batch of bean dip and one of mashed beans were found to contain large numbers of coagulase-positive S. aureus (>100,000/g). / Graduation date: 1982

Thesis (M.A.) - Simon Fraser University, 2005. / Theses (Dept. of Archaeology) / Simon Fraser University. Also issued in digital format and available on the World Wide Web.

Reproduction de : Thèse d'exercice : Pharmacie : Nantes : 2008. / Bibliogr.

Thesis (M.S.) in Food Science and Human Nutrition--University of Maine, 2009. / Includes vita. Includes bibliographical references (leaves 146-178).

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