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Changes in exhaled volatile organic compounds following indirect bronchial challenge in suspected asthma
Adam Peel, Ran Wang, Waqar Ahmed, Iain R. White, Maxim Wilkinson, Yoon K. Loke, Andrew M. Wilson, Stephen J. Fowler, 2023, original scientific article

Abstract: Background Inhaled mannitol provokes bronchoconstriction via mediators released during osmotic degranulation of inflammatory cells, and, hence represents a useful diagnostic test for asthma and model for acute attacks. We hypothesised that the mannitol challenge would trigger changes in exhaled volatile organic compounds (VOCs), generating both candidate biomarkers and novel insights into their origin. Methods Participants with a clinical diagnosis of asthma, or undergoing investigation for suspected asthma, were recruited. Inhaled mannitol challenges were performed, followed by a sham challenge after 2 weeks in participants with bronchial hyper-responsiveness (BHR). VOCs were collected before and after challenges and analysed using gas chromatography–mass spectrometry. Results Forty-six patients (mean (SD) age 52 (16) years) completed a mannitol challenge, of which 16 (35%) were positive, and 15 of these completed a sham challenge. Quantities of 16 of 51 identified VOCs changed following mannitol challenge (p<0.05), of which 11 contributed to a multivariate sparse partial least square discriminative analysis model, with a classification error rate of 13.8%. Five of these 16 VOCs also changed (p<0.05) in quantity following the sham challenge, along with four further VOCs. In patients with BHR to mannitol distinct postchallenge VOC signatures were observed compared with post-sham challenge. Conclusion Inhalation of mannitol was associated with changes in breath VOCs, and in people with BHR resulted in a distinct exhaled breath profile when compared with a sham challenge. These differentially expressed VOCs are likely associated with acute airway inflammation and/or bronchoconstriction and merit further investigation as potential biomarkers in asthma.
Keywords: asthma, exhaled volatile organic compounds, pulmonology, breath metabolomics
Published in RUNG: 31.07.2023; Views: 1140; Downloads: 3
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Distributed agreement in participial sandwiched configurations
Franc Marušič, Andrew Nevins, 2020, independent scientific component part or a chapter in a monograph

Abstract: In recent years, several proposals have appeared that try to model the patterns of agreement with coordinate noun phrases found in South Slavic Languages. We investigate agreement in so-called sandwiched configurations, whereby a coordinated noun phrase sits between two agreeing participles. In such cases, the two participles do not necessarily agree with each other, given a scenario in which the first and the second conjunct have different phi-features. This means the two participles choose their target of agreement independently. We argue the results of our experimental study favor an approach to agreement that places it partially in PF.
Keywords: Syntax, Agreement, Coordination, sandwiched agreement
Published in RUNG: 26.02.2020; Views: 3027; Downloads: 109
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Circadian rhythm of exhaled biomarkers in health and asthma
Max Wilkinson, Robert Maidstone, Andrew Loudon, John Blaikley, Iain R. White, Dave Singh, David Ray, Royston Goodacre, Stephen Fowler, Hannah Durrington, 2019, original scientific article

Abstract: Circadian rhythms control many biological processes in the body in both health and disease. Greater understanding of diurnal variability in disease related biomarkers is crucial for their application in clinical practice and biomarkers of circadian rhythm are required to facilitate further research into disturbed chronicity. To determine if fractional exhaled nitric oxide and breath volatile biomarkers vary rhythmically during the day in healthy and asthmatic individuals. Ten individuals with moderate, atopic asthma (on regular inhaled corticosteroids) and 10 healthy volunteers (all non-smokers) completed an overnight visit where their exhaled breath volatiles and forced exhaled nitric oxide levels were collected every 6 h. Breath volatiles were analysed using gas chromatography mass spectrometry, after trapping these volatiles on sorbent materials for thermal desorption. Nine breath volatiles (including acetone and isoprene) exhibit diurnal variation across all individuals. Furthermore the circadian pattern of several VOCs is altered in individuals with asthma and fractional exhaled nitric oxide is rhythmic in asthma but not in healthy controls. Markers of circadian rhythm can be identified in breath and may offer insight into circadian profiling to help treat disease. Additionally this work suggests that time of day must be controlled when designing future biomarker discovery studies. Further work is required with larger cohorts to validate and extend these findings.
Keywords: VOCs, breath, asthma, circadian
Published in RUNG: 21.10.2019; Views: 3482; Downloads: 0
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Real-time multi-marker measurement of organic compounds in human breath: Towards fingerprinting breath
Iain R. White, Kerry A Willis, Christopher Whyte, Rebecca Cordell, Robert S Blake, Andrew J Wardlaw, 2013, original scientific article

Abstract: The prospects for exploiting proton transfer reaction-time of flight-mass spectrometry (PTR-ToF-MS) in medical diagnostics are illustrated through a series of case studies. Measurements of acetone levels in the breath of 68 healthy people are presented along with a longitudinal study of a single person over a period of 1 month. The median acetone concentration across the population was 484 ppbV with a geometric standard deviation (GSD) of 1.6, whilst the average GSD during the single subject longtitudinal study was 1.5. An additional case study is presented which highlights the potential of PTR-ToF-MS in pharmacokinetic studies, based upon the analysis of online breath samples of a person following the consumption of ethanol. PTR-ToF-MS comes into its own when information across a wide mass range is required, particularly when such information must be gathered in a short time during a breathing cycle. To illustrate this property, multicomponent breath analysis in a small study of cystic fibrosis patients is detailed, which provides tentative evidence that online PTR-ToF-MS analysis of tidal breath can distinguish between active infection and non-infected patients.
Keywords: Volatile Organic Compounds, breath, proton transfer reaction mass spectrometry, Cystic Fibrosis
Published in RUNG: 22.07.2019; Views: 3518; Downloads: 0
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Metabolite profiling of the ripening of Mangoes Mangifera indica L. cv. ‘Tommy Atkins’ by real-time measurement of volatile organic compounds
Iain R. White, Robert S Blake, Andrew J Taylor, Paul S Monks, 2016, original scientific article

Abstract: Real-time profiling of mango ripening based on proton transfer reaction-time of flight-mass spectrometry (PTR–ToF–MS) of small molecular weight volatile organic compounds (VOCs), is demonstrated using headspace measurements of ‘Tommy Atkins’ mangoes. VOC metabolites produced during the ripening process were sampled directly, which enabled simultaneous and rapid detection of a wide range of compounds. Headspace measurements of ‘Keitt’ mangoes were also conducted for comparison. A principle component analysis of the results indicated that several mass channels were not only key to the ripening process but could also be used to distinguish between mango cultivars. The identities of 22 of these channels, tentatively speciated using contemporaneous GC–MS measurements of sorbent tubes, are rationalized through examination of the biochemical pathways that produce volatile flavour components. Results are discussed with relevance to the potential of headspace analysers and electronic noses in future fruit ripening and quality studies.
Keywords: Mangifera indica, Tommy Atkins, PTR–ToF–MS, VOCs, Ripening, Mango
Published in RUNG: 18.07.2019; Views: 3097; Downloads: 0
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Increased sensitivity in proton transfer reaction mass spectrometry by incorporation of a radio frequency ion funnel
Shane Barber, Robert S Blake, Iain R. White, Paul S Monks, Fraser Reich, Stephen Mullock, Andrew M Ellis, 2012, original scientific article

Abstract: A drift tube capable of simultaneously functioning as an ion funnel is demonstrated in proton transfer reaction mass spectrometry (PTR-MS) for the first time. The ion funnel enables a much higher proportion of ions to exit the drift tube and enter the mass spectrometer than would otherwise be the case. An increase in the detection sensitivity for volatile organic compounds of between 1 and 2 orders of magnitude is delivered, as demonstrated using several compounds. Other aspects of analytical performance explored in this study include the effective E/N (ratio of electric field to number density of the gas) and dynamic range over which the drift tube is operated. The dual-purpose drift tube/ion funnel can be coupled to various types of mass spectrometers to increase the detection sensitivity and may therefore offer considerable benefits in PTR-MS work.
Keywords: Analytical performance, Detection sensitivity, Drift tube, Dynamic range, Ion funnels, Proton-transfer reaction mass spectrometry, Volatile organic compounds
Published in RUNG: 18.07.2019; Views: 3122; Downloads: 0
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Distribution of gaseous and particulate organic composition during dark α-pinene ozonolysis
Marie Camredon, Jacqueline F Hamilton, Mohammed S Alam, Kevin P Wyche, Timo Carr, Iain R. White, Paul S Monks, Andrew R Rickard, William J Bloss, 2010, original scientific article

Abstract: Secondary Organic Aerosol (SOA) affects atmospheric composition, air quality and radiative transfer, however major difficulties are encountered in the development of reliable models for SOA formation. Constraints on processes involved in SOA formation can be obtained by interpreting the speciation and evolution of organics in the gaseous and condensed phase simultaneously. In this study we investigate SOA formation from dark α-pinene ozonolysis with particular emphasis upon the mass distribution of gaseous and particulate organic species. A detailed model for SOA formation is compared with the results from experiments performed in the EUropean PHOtoREactor (EUPHORE) simulation chamber, including on-line gas-phase composition obtained from Chemical-Ionization-Reaction Time-Of-Flight Mass-Spectrometry measurements, and off-line analysis of SOA samples performed by Ion Trap Mass Spectrometry and Liquid Chromatography. The temporal profile of SOA mass concentration is relatively well reproduced by the model. Sensitivity analysis highlights the importance of the choice of vapour pressure estimation method, and the potential influence of condensed phase chemistry. Comparisons of the simulated gaseous-and condensed-phase mass distributions with those observed show a generally good agreement. The simulated speciation has been used to (i) propose a chemical structure for the principal gaseous semi-volatile organic compounds and condensed monomer organic species, (ii) provide evidence for the occurrence of recently suggested radical isomerisation channels not included in the basic model, and (iii) explore the possible contribution of a range of accretion reactions occurring in the condensed phase. We find that oligomer formation through esterification reactions gives the best agreement between the observed and simulated mass spectra
Keywords: Aerosol, Aerosol formation, Smog chamber
Published in RUNG: 18.07.2019; Views: 3100; Downloads: 0
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Trace detection of C2H2 in ambient air using continuous wave cavity ring-down spectroscopy combined with sample pre-concentration
Manik Pradhan, Ruth Lindley, Roberto Grilli, Iain R. White, Damien Martin, Orr-Ewing Andrew, 2008, original scientific article

Abstract: Continuous wave cavity ring-down spectroscopy (cw-CRDS) coupled with sample pre-concentration has been used to measure acetylene (C2H2) mixing ratios in ambient air. Measurements were made in the near-infrared region (λ∼1535.393 nm), using the P(17) rotational line of the (ν1+ν3) vibrational combination band, a region free from interference by overlapping spectral absorption features of other air constituents. The spectrometer is shown to be capable of fast, quantitative and precise C2H2 mixing ratio determinations without the need for gas chromatographic (GC) separation. The current detection limit of the spectrometer following sample pre-concentration is estimated to be 35 parts per trillion by volume (pptv), which is sufficient for direct atmospheric detection of C2H2 at concentrations typical of both urban and rural environments. The CRDS apparatus performance was compared with an instrument using GC separation and flame ionization detection (GC-FID); both techniques were used to analyze air samples collected within and outside the laboratory. These measurements were shown to be in quantitative agreement. The indoor air sample was found to contain C2H2 at a mixing ratio of 3.87±0.22 ppbv (3.90±0.23 ppbv by GC-FID), and the C2H2 fractions in the outside air samples collected on two separate days from urban locations were 1.83±0.20 and 0.69±0.14 ppbv (1.18±0.09 and 0.60±0.04 ppbv by GC-FID). The discrepancy in the first outdoor air sample is attributed to degradation over a 2-month interval between the cw-CRDS and GC-FID analyses.
Keywords: Rotational Line, Cavity Enhance Absorption Spectroscopy, Adsorbent Trap, Trace Atmospheric Constituent, CRDS Instrument
Published in RUNG: 15.07.2019; Views: 3434; Downloads: 0
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Elided Clausal Conjunction Is Not the Only Source of Closest‐Conjunct Agreement: A Picture‐Matching Study
Boban Arsenijević, Jana Willer-Gold, Nadira Aljović, Nermina Čordalija, Marijana Kresić, Nedžad Leko, Frane Malenica, Franc Marušič, Tanja Milićev, Nataša Milićević, Petra Mišmaš, Ivana Mitić, Anita Peti-Stantić, Branimir Stanković, Jelena Tušek, Andrew Nevins, 2019, original scientific article

Abstract: A recurring hypothesis about the agreement phenomena generalized as closest‐conjunct agreement takes this pattern to result from reduced clausal conjunction, simply displaying the agreement of the verb with the nonconjoined subject of the clause whose content survives ellipsis (Aoun, Benmamoun & Sportiche 1994, 1999; see also Wilder 1997). Closest‐conjunct agreement is the dominant agreement pattern in the South Slavic languages Slovenian and Bosnian/Croatian/Serbian. A natural question is whether closest‐conjunct agreement in these varieties may indeed be analyzed as entirely derived from conjunction reduction. In this article, we report on two experiments conducted to test this. The results reject the hypothesis as far as these languages are concerned, thereby upholding the relevance of models developed to account for closest‐conjunct agreement within theories of agreement.
Keywords: Conjunct agreement, Clausal conjunction, Experimental syntax
Published in RUNG: 08.04.2019; Views: 12228; Downloads: 136
.pdf Full text (653,34 KB)

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