Biofilm formation under industrially-relevant conditions.

Biofilms are considered to be one of the most prevalent and successful modes of life on Earth, and the prevailing lifestyle for microorganisms. Enabling bacteria to adapt to an incredibly diverse array of environments and extreme conditions, biofilms are a major contaminant of both medical and industrial settings. Indeed, approximately 80% of microbial infections are associated with biofilm formation, whilst the damage caused by biofilms in industry is estimated at between 2 – 3% of global GDP per annum. In this body of work, the effect of two industrially-relevant shear conditions on biofilm formation by the reference Pseudomonas aeruginosa (Ps. a.) strains PA01 and PA14 was investigated, as well as the effect of growth conditions and growth medium components on curli gene expression in E. coli K12 PHL644. The CBC biofilm reactor was used to model low and high shear conditions at 75 RPM and 350 RPM respectively, and biofilms grown over a time period of 96 hours. High levels of the intracellular second messenger c-di-GMP are regarded as the determining factor for Ps. a. sessility and progression of the biofilm phenotype, thus the c-di-GMP-responsive cdrA::gfp reporter was used to measure intracellular c-di-GMP levels of PA01 and PA14 under low and high shear conditions. Biofilms were analysed via confocal laser scanning microscopy and staining of extracellular DNA (eDNA) and the exopolysaccharides Psl and Pel, which are all form crucial components of a self-produced and protective extracellular matrix that surrounds and enmeshes Ps. a. within a biofilm. Under high shear at 350 RPM, intracellular c-di-GMP levels of initially adhered (at 24 hours) bacteria were increased, resulting in increased production of exopolysaccharides and formation of early aggregative structures. Shear conditions were shown to impact upon biofilm development and maturation of three-dimensional structures: crucially, mushroom-shaped macrocolonies, which are archetypal of Ps. a. biofilm formation, did not form under high shear. Under low shear at 75 RPM, Psl and Pel were organised into networks of fibre-like structures that penetrated throughout well-established basal biofilms (> 72 hours), which is in agreement with the work of others (with respect to Psl), but is a novel observation of Pel morphology as produced by PA14. The work presented in this thesis therefore provides further insight on the variety of Psl and Pel morphologies that exhibit different structures, spatial and temporal organisation, and function across PA01 and PA14 biofilms in response to either low or high shear conditions. Whilst similarities were observed between the two strains, PA01 and PA14 exhibited distinct responses to the imposed shear regime, in terms of initial surface colonisation, time taken for mature structures to emerge, and exopolysaccharide production. Biofilms produced by E. coli PHL644 were grown using the Duran bottle model, via a method previously developed by the Overton laboratory. High levels of the transcriptional regulator CsgD are regarded as ‘master switch’ that determines biofilm formation in E. coli, thus the CsgD-responsive csgB::gfp reporter was used to measure curli gene expression in response to growth in LB broth (a rich medium) versus M63+ minimal medium, different concentrations of glucose (at 0 mM, 1 mM, 10 mM and 100 mM), and incubation at different temperatures (at 25 oC, 28 oC, 30 oC and 37 oC), and identify parameters which resulted in maximal expression of curli. Planktonic cell samples were taken from the tops of the Duran bottles, and sedimented cell samples taken from the bottom of the Duran bottles for comparative analysis of growth via spectrophotometry at OD600 and csgB::gfp fluorescence by flow cytometry. Curli gene expression was found to be highest in cultures grown in M63+ minimal medium, with a glucose concentration of 10 mM and at an incubation temperature of 30 oC, which is in agreement with comparable studies in the literature. Of interest was the fact that an inverse relationship between biomass concentration (as defined by OD600 values) and csgB::gfp fluorescence was observed. Curli gene expression in sedimented cell samples was consistently lower than that of planktonic cell cultures across all experimental subsets, suggesting that planktonic cells are physically more capable of surface attachment, and curli expression may be downregulated when in a sediment; exemplifying the importance and function of curli as the initial adhesin of E. coli K12. Overall, this body of work concludes that different shear conditions can impact upon Ps. a. biofilm development and induce distinct organisation of the ECM, and that the CBC biofilm reactor is a suitable experimental model for assessing the impact of turbulent flow regimes, akin to those experienced in industrial manufacturing plants, on biofilm formation and composition. Additionally, this body of work also demonstrated that the Duran bottle model is also a suitable method for biofilm formation, and for investigating the effect of a wide array of growth conditions on E. coli K12 biofilm formation and curli gene expression. Parameters that resulted in maximal curli gene expression in E. coli K12 PHL644 cultures grown via the Duran bottle method under the conditions tested were identified, and could be further used to optimise production of a physically robust E. coli biofilm for use in biocatalysis or certain industrial settings

PACE: Program of All-inclusive Care of the Elderly

Educational Objectives 1. To describe the origin of PACE. 2. To identify essential services provided by the PACE model

International University Students in Canada: Obtaining the Information Needed for Policy Making

International university students represent sources of goodwill and benefits for their host countries. Unfortunately, Canada, although still one of the major receiving countries, has seen a substantial decline in international enrolment during the 1980s. Reasons proposed for this decline include differential fees, insufficient financial support, quotas, and employment restrictions. The problems most frequently encountered by international students in Canada involve immigration procedures, accommodation, language, loneliness, and funding. The formulation of policies concerning these problems and other matters relevant to international university students occurs at the federal, provincial, and institutional levels. Even though the main forces driving such policies are cultural, financial, and political, the policies should take into account information about the needs, desires, and experiences of international students. A comprehensive 1986-87 University of Alberta survey of international students served as a case study to demonstrate how research can better inform policy making in this area. Respondents suggested that they would be helped by being allowed to work in Canada while studying and after graduation, which is a federal policy area, and by having more scholarships available to them and differential fees removed, both of which are provincial and institutional policy areas.Les pays qui reçoivent des étudiants étrangers en retirent bienveillance et avantages. Malheureusement, bien que le Canada soit encore un des pays qui reçoivent le plus, le nombre d'inscriptions venant de l'étranger y a considérable-ment diminué au cours des années 80. Les raisons avancées pour cette baisse comprennent les droits d'inscription différentiels, l'insuffisance de l'appui financier, les quotas et les retrictions d'emploi. Les difficultés auxquelles les étudiants étrangers doivent faire face le plus souvent au Canada se rapportent au processus d'immigrations, au financement, au logement, à la langue et à isolement. La formulation des politiques relatives à toutes ces questions et à d'autres concernant ces étudiants se fait aux niveaux du pays, de la province et de l'établissement. Ces politiques se fondent surtout sur des motifs culturels, économiques et politiques. Elles devraient toutefois tenir compte des besoins, des désirs et de l'expérience des étudiants étrangers. Une enquête détaillée menée auprès des étudiants étrangers par l'Universté de l'Alberta en 1986-1987 a servi pour d'étude de cas pour démontrer comment la recherche peut aider à éclairer les responsables de l'établissement des politiques. Dans cette enquête, les intéressés ont fait savoir qu'il leur serait utile d'avoir la permission de travailler au Canada pendant leurs études et après l'obtention de leur diplome, ce qui est une politique établie au niveau fédéral. Ils désireraient aussi avoir accès à davantage de bourses et voir annuler les frais différentiels, ce qui relève des provinces et des établissements

Using Metaphors to Depict Canada’s Adult Literacy Research Since the Mid-1980s

This study examined the evolution in adult literacy research since the founding of The Canadian Journal for the Study of Adult Education (CJSAE) and the rise of the contemporary knowledge base in Canadian adult literacy. Three research questions guided the investigation which employed a critical discourse analysis (CDA) method. A text analysis grid was constructed and was used across several data sources representing Canadian literacy scholarship. Results indicate that seven metaphors can be used to depict the current state of literacy scholarship. These findings shape a triangle of three solitudes: academic researchers, practitioners, and government sponsors

Non-pathogenic Escherichia coli biofilms: effects of growth conditions and surface properties on structure and curli gene expression

Biofilm formation is a harmful phenomenon in many areas, such as in industry and clinically, but offers advantages in the field of biocatalysis for the generation of robust biocatalytic platforms. In this work, we optimised growth conditions for the production of Escherichia coli biofilms by three strains (PHL644, a K-12 derivative with enhanced expression of the adhesin curli; the commercially-used strain BL21; and the probiotic Nissle 1917) on a variety of surfaces (plastics, stainless steel and PTFE). E. coli PHL644 and PTFE were chosen as optimal strain and substratum, respectively, and conditions (including medium, temperature, and glucose concentration) for biofilm growth were determined. Finally, the impact of these growth conditions on expression of the curli genes was determined using flow cytometry for planktonic and sedimented cells. We reveal new insights into the formation of biofilms and expression of curli in E. coli K-12 in response to environmental conditions

Sources d'information sur la santé et la mortalité en Afrique de l'Ouest : une étude comparative

Version anglaise disponible dans la Bibliothèque numérique du CRDI: West African sources of health and mortality information : a comparative revie

DNA methylation affects nuclear organization, histone modifications, and linker histone binding but not chromatin compaction

DNA methylation has been implicated in chromatin condensation and nuclear organization, especially at sites of constitutive heterochromatin. How this is mediated has not been clear. In this study, using mutant mouse embryonic stem cells completely lacking in DNA methylation, we show that DNA methylation affects nuclear organization and nucleosome structure but not chromatin compaction. In the absence of DNA methylation, there is increased nuclear clustering of pericentric heterochromatin and extensive changes in primary chromatin structure. Global levels of histone H3 methylation and acetylation are altered, and there is a decrease in the mobility of linker histones. However, the compaction of both bulk chromatin and heterochromatin, as assayed by nuclease digestion and sucrose gradient sedimentation, is unaltered by the loss of DNA methylation. This study shows how the complete loss of a major epigenetic mark can have an impact on unexpected levels of chromatin structure and nuclear organization and provides evidence for a novel link between DNA methylation and linker histones in the regulation of chromatin structure

From transformative learning to social change? Using action research to explore and improve informal complaints management in an NHS trust

Background: The number of complaints concerning aspects of care from patients and/or carers have increased over time. Yet, in spite of a growing body of national and international literature on health care complaints there is a lack of knowledge around how nurses and midwives manage informal complaints at ward level, or staff needs in relation to this. Aim: Using an Action research (AR) approach with mixed methods, four phases and four cycles, the aim was to explore informal complaints management by nurses and midwives at ward level. We discuss the AR process primarily in connection with learning and service change, drawing from the qualitative data in this paper. Findings: The analysis of the collected qualitative data resulted in three main themes related to the complexities of complaints and complaints management, staff support needs and the existing ambiguous complaints systems which are hard for both staff and servicer users to negotiate. The AR approach facilitated learning and change in participants in relation to views on complaints management, and the main issues around complaints management in the collaborating trust. Conclusions: The extant body of research on complaints does not sufficiently recognise the complexity of complaints and informal complaints management or the complaints systems in place. Needs based staff training can help support staff to manage informal complaints more effectively

West African sources of health and mortality information : a comparative review

French version available in IDRC Digital Library: Sources d'information sur la santé et la mortalité en Afrique de l'Ouest : une étude comparativ

Confirming nasogastric tube position with electromagnetic tracking versus pH or X-ray and tube radio-opacity

Recent evidence suggests official statistics greatly underestimate the occurrence of complications from misplaced nasogastric (NG) tubes, even when detected. Current methods of confirming tube position do not provide adequate protection from misplacement. In addition, some tubes are inadequately radio-opaque. We prospectively audited placement of Cortrak polyurethane tubes (PUTs) to determine: accuracy of the electromagnetic (EM) trace in confirming tube position, radio-opacity of PUTs compared with previously placed polyvinylchloride (PVC) Ryles tubes and whether 12 French PUTs can be used to aspirate gastric residual volumes (GRVs). A total of 127 PUTs were placed in 113 patients. EM traces accurately confirmed tube position compared with X-ray (100% agreement). A 'gastric' EM trace has been defined for future use by other operators. PUTs were adequately radio-opaque with good agreement between interpreters (>98%) whereas PVC Ryles tubes were insufficiently radio-opaque (57-73%), invisible in 23% of cases and with poor agreement between interpreters leaving risk of error. The alternative of using pH confirmation was not possible in 44%. In these cases subsequent X-ray incurred a 2-hour delay to feed and medicines. In addition, neither post-placement pH testing nor X-ray warn of lung placement and potential trauma, whereas the EM trace warned of lung placement prior to damage in 7% of placements. 12 French, single-port PUTs appear adequate to aspirate large GRVs. EM tracing may be considered a standalone method of confirming NG tube position. Corflo (Cortrak) PUTs are adequately radio-opaque. Use of PVC Ryles and other inadequately radio-opaque tubes should stop