Browsing by Author "Fowler, Dawn P."
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Item Open Access Analysis of volatile marker compounds in body fluid samples from patients with gastrointestinal disease(Cranfield University, 2010-09) Fowler, Dawn P.; Turner, Claire; Walker, ChristopherCauses of gastrointestinal diseases such as ulcerative colitis (UC) Crohn’s disease (CD) and irritable bowel syndrome (IBS) are not yet completely understood and clinical investigation for diagnosis is invasive, costly and time consuming. Disease may originate from the host or in combination with commensal enteric bacteria, notably sulphate reducing bacteria. Examination of volatile compounds from clinical samples may provide indicators and better understanding into aetiology of these conditions and provide biomarkers for individual disease.Cont/d.Item Open Access Diversity and distribution of sulphate-reducing bacteria in human faeces from healthy subjects and patients with inflammatory bowel disease(2012-06-01T00:00:00Z) Jia, Wenjing; Whitehead, Rebekah N.; Griffiths, Lesley; Dawson, Claire; Bai, Hao; Waring, Rosemary H.; Ramsden, David B.; Hunter, John O.; Cauchi, Michael; Bessant, Conrad M.; Fowler, Dawn P.; Walton, Christopher; Turner, Claire; Cole, Jeffrey A.The relative abundance of different groups of sulphate-reducing bacteria (SRB) in faecal DNA collected before and after therapy from patients suffering from Crohn's disease (CD), irritable bowel syndrome (IBS) or ulcerative colitis (UC) has been compared with that from healthy controls. Growth tests revealed that SRB were not more abundant in samples from patients with CD before treatment than in the healthy control group. For most of the 128 samples available, these preliminary results were confirmed using degenerate PCR primers that amplify the dsrAB gene. However, some samples from patients with CD before treatment contained a growth inhibitor that was absent from IBS or UC samples. In-depth sequencing of PCR-generated dsrB fragments revealed that the diversity detected was surprisingly low, with only eight strains of SRB and the sulphite-reducing bacterium, Bilophila wadsworthia, detected above the 0.1% threshold. The proportion of the two major species detected, B.wadsworthia and Desulfovibrio piger, was as high as 93.5% of the total SRB population in the healthy control group and lower in all patient groups. Four previously undescribed species were found: it is impossible to predict whether they are sulphate or sulphite-reducing bacteria.Item Open Access Enteral feeding reduces metabolic activity of the intestinal microbiome in Crohn’s disease: an observational study(Nature Publishing Group, 2016-05-11) Walton, Christopher; Montoya, M. P. B.; Fowler, Dawn P.; Turner, Claire; Jia, W.; Whitehead, Rebekah N.; Griffiths, Lesley; Waring, Rosemary H.; Ramsden, David B.; Cole, Jeffrey A.; Cauchi, Michael; Bessant, Conrad M.; Naylor, J.; Hunter, John O.BACKGROUND/OBJECTIVES: Enteral feeding will induce remission in as many as 80–90% of compliant patients with active Crohn’s disease (CD), but its method of action remains uncertain. This study was designed to examine its effects on the colonic microbiome. METHODS/SUBJECTS: Healthy volunteers and patients with CD followed a regimen confined to enteral feeds alone for 1 or 2 weeks, respectively. Chemicals excreted on breath or in faeces were characterised at the start and at the end of the feeding period by gas chromatography/mass spectrometry. RESULTS: One week of feeding in healthy volunteers caused significant changes in stool colour and deterioration in breath odour, together with increased excretion of phenol and indoles on the breath. Feeding for 2 weeks in patients with CD produced significant improvements in symptoms and a decrease in the concentration of C-reactive protein. The faecal concentrations of microbial products, including short-chain fatty acids (SCFAs), and potentially toxic substances, including 1-propanol, 1-butanol and the methyl and ethyl esters of SCFAs, showed significant falls. CONCLUSIONS: A significant change occurs in the production of microbial metabolites after enteral feeding in both healthy volunteers and patients with CD. Many of those detected in CD are toxic and may feasibly lead to the immunological attack on the gut microbiota, which is characteristic of inflammatory bowel disease. The reduction in the production of such metabolites after enteral feeding may be the reason for its effectiveness in CD.Item Open Access Mid-IR spectroscopic instrumentation for point-of-care diagnosis using a hollow silica waveguide gas cell(International Society for Optics and Photonics - SPIE, 2017-02-17) Francis, Daniel; Hodgkinson, Jane; Walton, Christopher; Sizer, Jeremy; Black, Paul; Livingstone, Beth; Fowler, Dawn P.; Patel, Mitesh K.; Tatam, Ralph P.Laser spectroscopy provides the basis of instrumentation developed for the diagnosis of infectious disease, via quantification of organic biomarkers that are produced by associated bacteria. The technology is centred on a multichannel pulsed quantum cascade laser system that allows multiple lasers with different wavelengths to be used simultaneously, each selected to monitor a different diagnostic biomarker. The instrument also utilizes a hollow silica waveguide (HSW) gas cell which has a very high ratio of interaction pathlength to internal volume. This allows sensitive detection of low volume gas species from small volume biological samples. The spectroscopic performance of a range of HSW gas cells with different lengths and bore diameters has been assessed using methane as a test gas and a best-case limit of detection of 0.26 ppm was determined. The response time of this cell was measured as a 1,000 sccm flow of methane passed through it and was found to be 0.75 s. These results are compared with those obtained using a multi-pass Herriot cell. A prototype instrument has been built and approved for clinical trials for detection of lung infection in acute-care patients via analysis of ventilator breath. Demonstration of the instrument for headspace gas analysis is made by monitoring the methane emission from bovine faeces. The manufacture of a hospital-ready device for monitoring biomarkers of infection in the exhaled breath of intensive care ventilator patients is also presented.