Publications
16 results found
Radhakrishnan ST, Gallagher KI, Mullish BH, et al., 2023, Rectal swabs as a viable alternative to faecal sampling for the analysis of gut microbiota functionality and composition, Scientific Reports, Vol: 13, Pages: 1-9, ISSN: 2045-2322
Faecal or biopsy samples are frequently used to analyse the gut microbiota, but issues remain with the provision and collection of such samples. Rectal swabs are widely-utilised in clinical practice and previous data demonstrate their potential role in microbiota analyses; however, studies to date have been heterogenous, and there are a particular lack of data concerning the utility of swabs for the analysis of the microbiota’s functionality and metabolome. We compared paired stool and rectal swab samples from healthy individuals to investigate whether rectal swabs are a reliable proxy for faecal sampling. There were no significant differences in key alpha and beta diversity measures between swab and faecal samples, and inter-subject variability was preserved. Additionally, no significant differences were demonstrated in abundance of major annotated phyla. Inferred gut functionality using Tax4Fun2 showed excellent correlation between the two sampling techniques (Pearson’s coefficient r = 0.9217, P < 0.0001). Proton nuclear magnetic resonance (1H NMR) spectroscopy enabled the detection of 20 metabolites, with overall excellent correlation identified between rectal swab and faecal samples for levels all metabolites collectively, although more variable degrees of association between swab and stool for levels of individual metabolites. These data support the utility of rectal swabs in both compositional and functional analyses of the gut microbiota.
Valdivia-Garcia MA, Chappell KE, Camuzeaux S, et al., 2022, Improved quantitation of short-chain carboxylic acids in human biofluids using 3-nitrophenylhydrazine derivatization and liquid chromatography with tandem mass spectrometry (LC-MS/MS), JOURNAL OF PHARMACEUTICAL AND BIOMEDICAL ANALYSIS, Vol: 221, ISSN: 0731-7085
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- Citations: 3
Alvarez-Jarreta J, Rodrigues PRS, Fahy E, et al., 2021, LipidFinder 2.0: advanced informatics pipeline for lipidomics discovery applications, Bioinformatics, Vol: 37, Pages: 1478-1479, ISSN: 1367-4803
We present LipidFinder 2.0, incorporating four new modules that apply artefact filters, remove lipid and contaminant stacks, in-source fragments and salt clusters, and a new isotope deletion method which is significantly more sensitive than available open-access alternatives. We also incorporate a novel false discovery rate method, utilizing a target–decoy strategy, which allows users to assess data quality. A renewed lipid profiling method is introduced which searches three different databases from LIPID MAPS and returns bulk lipid structures only, and a lipid category scatter plot with color blind friendly pallet. An API interface with XCMS Online is made available on LipidFinder’s online version. We show using real data that LipidFinder 2.0 provides a significant improvement over non-lipid metabolite filtering and lipid profiling, compared to available tools.
Radhakrishnan ST, Mullish BH, Gallagher K, et al., 2021, RECTAL SWABS AS A VIABLE ALTERNATIVE TO FECAL SAMPLING FOR THE ANALYSIS OF GUT MICROBIOME FUNCTIONALITY AS WELL AS COMPOSITION, Society-for-Surgery-of-the-Alimentary-Tract Annual Meeting at Digestive Disease Week (DDW), Publisher: W B SAUNDERS CO-ELSEVIER INC, Pages: S733-S733, ISSN: 0016-5085
Valdivia-Garcia M, Weir P, Graham DW, et al., 2019, Predicted impact of climate change on trihalomethanes formation in drinking water treatment, Scientific Reports, Vol: 9, Pages: 1-10, ISSN: 2045-2322
Quantitative predictions of impacts on public water supplies are essential for planning climate change adaptations. Monitoring data from five full-scale Scottish drinking water treatment plants (DWTPs) showed that significant correlations exist between conditionally carcinogenic trihalomethanes (THMs) levels, water temperature (r = 0.812, p = 0.0013) and dissolved organic carbon (DOC) (r = 0.892, p < 0.0001), respectively. The strong seasonality of these parameters demonstrated how climate can influence THMs formation. We quantified with laboratory experiments the sensitivity of THMs formation to changes in water temperature and DOC concentration. The laboratory data accurately reproduced real-world THM formation in the DWTPs. We then combined these validated relationships with information from the literature about future trends in mean summer temperatures and surface water DOC in the British Isles, to estimate future global warming impacts on THMs formation in DWTPs that use chlorine for disinfection. An increase in mean summer temperatures will likely increase THM formation, with a 1.8 °C temperature increase and 39% THMs increase by 2050 representing our mid-range scenario. Such an increase has major implications to potable water around the world, either an increased health risk or increased water treatment costs to maintain an equivalent quality potable supply.
Valdivia-Garcia M, Weir P, Frogbrook Z, et al., 2016, Climatic, geographic and operational determinants of trihalomethanes (THMs) in drinking water systems, Scientific Reports, Vol: 6, Pages: 1-12, ISSN: 2045-2322
Trihalomethanes (THMs) are conditionally carcinogenic compounds formed during chlorine disinfection in water treatment processes around the world. THMs occur especially when source waters are subject to marine influences, high and-or regular precipitation, and elevated levels of organic matter. THMs formation is then rooted in geographic, operational and climatic factors, the relative importance of which can only be derived from large datasets and may change in the future. Ninety three full-scale Scottish water treatment plants (WTPs) were assessed from Jan 2011 to Jan 2013 to identify factors that promote THMs formation. Correlation analysis showed that ambient temperature was the primary THMs formation predictor in potable water (r2 = 0.66, p < 0.05) and water distribution systems (r2 = 0.43, p = 0.04), while dissolved organic carbon (r2 = 0.55, p < 0.001) and chloride (indicating marine influence; r2 = 0.41, p < 0.001) also affected THMs formation. GIS mapping of median THMs levels indicated brominated THMs were most prevalent in coastal areas and on islands. This real-world dataset confirms both geographic and climatic factors are key to THMs formation. If ambient temperatures increase, THMs control will become more challenging, substantiating concerns about the impact of global warming on water quality.
Werner D, Valdivia-Garcia M, Weir P, et al., 2016, Trihalomethanes formation in point of use surface water disinfection with chlorine or chlorine dioxide tablets, WATER AND ENVIRONMENT JOURNAL, Vol: 30, Pages: 271-277, ISSN: 1747-6585
Valdivia-Garcia M, Werner D, Weir P, 2015, Exploratory statistical analysis of drinking water treatments and water characteristics in Scotland: Best predictors of trihalomethanes (THMs) formation, Publisher: AMER CHEMICAL SOC, ISSN: 0065-7727
Elshorbagy AK, Nijpels G, Valdivia-Garcia M, et al., 2013, S-Adenosylmethionine Is Associated with Fat Mass and Truncal Adiposity in Older Adults, JOURNAL OF NUTRITION, Vol: 143, Pages: 1982-1988, ISSN: 0022-3166
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- Citations: 34
Elshorbagy AK, Valdivia-Garcia M, Mattocks DAL, et al., 2013, Effect of taurine and N-acetylcysteine on methionine restriction-mediated adiposity resistance, METABOLISM-CLINICAL AND EXPERIMENTAL, Vol: 62, Pages: 509-517, ISSN: 0026-0495
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- Citations: 26
Elshorbagy AK, Valdivia-Garcia M, Graham IM, et al., 2012, The association of fasting plasma sulfur-containing compounds with BMI, serum lipids and apolipoproteins., Nutr Metab Cardiovasc Dis, Vol: 22, Pages: 1031-1038
BACKGROUND AND AIM: Sulfur amino acids are recognized as potent modulators of lipid metabolism. Plasma total cysteine (tCys) is associated with fat mass, obesity and serum LDL-cholesterol and apolipoprotein (Apo)-B in large population studies. It is not known how fasting plasma concentrations of cysteine precursors and products relate to these associations in humans, given that sulfur-containing compounds (SCC) influence rodent weight gain and serum lipids. METHODS AND RESULTS: We investigated the cross-sectional associations of fasting plasma SCC (methionine, total homocysteine, cystathionine, tCys, taurine and total glutathione) with BMI and fasting serum lipids and apolipoproteins in 854 men and women with and without cardiovascular disease (CVD). In multiple linear regression analysis adjusted for age, gender, CVD and other SCC, neither methionine, taurine, nor total glutathione was associated with BMI. Plasma taurine was, however, inversely related to HDL-cholesterol (partial r = -0.12, p = 0.004) and its associated apoA1 (partial r = -0.18, p < 0.001). Plasma cystathionine correlated positively with triglycerides and BMI, while tCys positively correlated with total cholesterol, LDL-cholesterol (partial r = 0.20, p < 0.001) and its associated apoB. The associations of SCC with serum lipids were independent of BMI. tCys was also independently associated with BMI (partial r = 0.20, p < 0.001) after adjustment for other SCC, glucose, lipids and apolipoproteins. CONCLUSIONS: Fasting tCys is associated with BMI independently of metabolically related SCC. Elevation of plasma SCC is generally associated with an unfavorable lipid profile. The negative relations of plasma taurine with HDL-C and apoA1 deserve further investigation.
Elshorbagy AK, Valdivia-Garcia M, Refsum H, et al., 2012, The Association of Cysteine with Obesity, Inflammatory Cytokines and Insulin Resistance in Hispanic Children and Adolescents, PLOS ONE, Vol: 7, ISSN: 1932-6203
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- Citations: 54
Elshorbagy AK, Church C, Valdivia-Garcia M, et al., 2012, Dietary cystine level affects metabolic rate and glycaemic control in adult mice, JOURNAL OF NUTRITIONAL BIOCHEMISTRY, Vol: 23, Pages: 332-340, ISSN: 0955-2863
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- Citations: 43
Aasheim ET, Elshorbagy AK, Diep LM, et al., 2011, Effect of bariatric surgery on sulphur amino acids and glutamate, BRITISH JOURNAL OF NUTRITION, Vol: 106, Pages: 432-440, ISSN: 0007-1145
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- Citations: 20
Elshorbagy AK, Valdivia-Garcia M, Mattocks DAL, et al., 2011, Cysteine supplementation reverses methionine restriction effects on rat adiposity: significance of stearoyl-coenzyme A desaturase, JOURNAL OF LIPID RESEARCH, Vol: 52, Pages: 104-112, ISSN: 0022-2275
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- Citations: 120
Elshorbagy AK, Valdivia-Garcia M, Refsum H, et al., 2010, Sulfur amino acids in methionine-restricted rats: Hyperhomocysteinemia, NUTRITION, Vol: 26, Pages: 1201-1204, ISSN: 0899-9007
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- Citations: 72
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