Browsing by Author "Fowler, Dawn"

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    DIABLO biomarker data (Detection of Infectious Agents By Laser Optics)
    (Cranfield University, 2019-04-04 13:25) Walton, Chris; Fowler, Dawn; Sizer, Jeremy; Patel, MItesh
    DIABLO - Detection of Infectious Agents By Laser Optics The aim of this project is to identify potential biomarkers for Clostridium difficile infection (CDI) in the stool of patients suffering with unexplained diarrhoea. It forms a part of a larger project aimed at developing an instrument for the point-of-care diagnosis of CDI, so an important aspect of this work is determination of markers which can be accessed rapidly (within a few minutes) from the sample with little or no prior sample preparation. The file "DIABLO Biomarker data.zip" contains the results of laboratory analysis of samples taken at Guy's and St Thomas' NHS Foundation Trust. Data are provided as SPSS and Excel files with a Word document containing explanatory notes on methods and data analysis. An early report of some of the results can be found in "Volatile biomarkers - poster.pdf".
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    Faecal volatile biomarkers of Clostridium difficile infection
    (PLOS (Public Library of Science), 2019-04-15) Patel, Mitesh; Fowler, Dawn; Sizer, Jeremy; Walton, Christopher
    Care of patients with potential CDI can involve isolation and use of antibiotics, often before a definitive diagnosis is available, impacting healthcare resource and contributing to antibiotic resistance. There is anecdotal evidence that the faeces of CDI patients have a distinctive odour, while it is well-established that changes in the gut microbiota are associated with changes in the volatile organic compounds (VOC) produced. A total of twenty-four candidate volatile biomarkers were identified from a review of the literature including in vitro, animal and human studies. Using thermal desorption-gas chromatography-time-of flight mass spectrometry (TD-GC-ToFMS), VOC emission rates were determined on stored frozen stool samples from 53 CDI-positive and 53 CDI-negative patients with unexplained diarrhoea which had previously been diagnosed using enzymatic and nucleic acid amplification tests. Sample preparation was limited to placement of a subsample in an appropriate container. Compounds exhibiting a statistically significant difference (p < 0.05) in emission rate between the CDI-positive and–negative groups and a corresponding area under the receiver-operator characteristic curve (ROC) >0.7 were considered potentially indicative of CDI. Seven compounds were so identified: propan-1-ol (ROC 0.75), 3-methylbutanal (ROC 0.84), ethyl propionate (ROC 0.81), hexanoic acid (ROC 0.73), 4-methylphenol (ROC 0.81), dodecane (ROC 0.80) and indole (ROC 0.85). A number of potential volatile biomarkers of CDI can be sampled rapidly and with little prior preparation from faecal samples of patients with diarrhoea. Of these 4-methylphenol (p-cresol) is of particular interest as it has been anecdotally linked to CDI and is closely related to the biology and virulence of Clostridium difficile. This approach shows promise for the rapid, point-of-care diagnosis of CDI with good sensitivity and specificity.
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    Instrumentation for quantitative analysis of volatile compounds emission at elevated temperatures. Part 2: Analysis of carbon fibre reinforced epoxy composite
    (Cranfield University, 2020-05-27 20:01) Lourenco, Celia; Francis, Daniel; Fowler, Dawn; E. Staines, Stephen; Hodgkinson, Jane; Walton, Christopher; Bergin, Sarah; Tatam, Ralph
    Data to support manuscript Part 2.
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    Quantification of liquid phase faecal odourants to evaluate membrane technology for wastewater reuse from decentralised sanitation facilities
    (Royal Society of Chemistry, 2018-11-29) Mercer, Edwina V.; Davey, Christopher J.; Campo Moreno, Pablo; Fowler, Dawn; Williams, Leon; Kolios, Athanasios; Parker, Alison; Tyrrel, Sean; Walton, Christopher; Cartmell, Elise; Pidou, Marc; McAdam, Ewan J.
    Public willingness to use decentralised sanitation facilities or arising water products is discouraged due to malodour, preventing improved sanitation practices or water reuse opportunities in low income countries Whilst odour is characterised in the gas phase, it originates in the liquid phase. Consequently, controlling odour at source could prevent gas-phase partitioning and limit produced water contamination. This study therefore developed an analytical method for the quantitation of a range of liquid phase volatile organic compounds (VOCs) classified into eight chemical groups, known to be primary indicators of faecal odour, to provide characterisation of real fluids and to permit evaluation of several potential membrane separation technologies for liquid phase odourant separation. The gas chromatography mass spectrometry method provided quantitation in the range of 0.005 mg L-1 to 100 mg L-1 with instrument detection limits ranging from 0.005 mg L-1 to 0.124 mg L-1. Linear calibration curves were achieved (r2 >0.99) with acceptable accuracy (77-115%) and precision (<15%) for quantitation in the calibration range below 1 mg L 1, and good accuracy (98-104%) and precision (<2%) determined for calibration in the range 1-100 mg L-1. Pre-concentration of real samples was facilitated via solid phase extraction. Subsequent application of the method to the evaluation of two thermally driven membranes based on hydrophilic (polyvinyl alcohol) and hydrophobic (polydimethylsiloxane) polymers evidenced contrasting separation profiles. Importantly, this study demonstrates the methods utility for liquid phase VOC determination which is of use to a range of disciplines, including healthcare professionals, taste and odour specialists and public health engineers.