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| 2. |
- Sehgal, R., et al.
(författare)
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Indole-3-propionic acid, a gut-derived tryptophan metabolite, associates with hepatic fibrosis
- 2021
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Ingår i: Nutrients. - : MDPI AG. - 2072-6643. ; 13:10
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Tidskriftsartikel (refereegranskat)abstract
- Background and Aims: Gut microbiota-derived metabolites play a vital role in maintenance of human health and progression of disorders, including obesity and type 2 diabetes (T2D). Indole-3-propionic acid (IPA), a gut-derived tryptophan metabolite, has been recently shown to be lower in individuals with obesity and T2D. IPA’s beneficial effect on liver health has been also explored in rodent and cell models. In this study, we investigated the association of IPA with human liver histology and transcriptomics, and the potential of IPA to reduce hepatic stellate cell activation in vitro. Methods: A total of 233 subjects (72% women; age 48.3 ± 9.3 years; BMI 43.1 ± 5.4 kg/m2) undergoing bariatric surgery with detailed liver histology were included. Circulating IPA levels were measured using LC-MS and liver transcriptomics with total RNA-sequencing. LX-2 cells were used to study hepatoprotective effect of IPA in cells activated by TGF-β1. Results: Circulating IPA levels were found to be lower in individuals with liver fibrosis compared to those without fibrosis (p = 0.039 for all participants; p = 0.013 for 153 individuals without T2D). Accordingly, levels of circulating IPA associated with expression of 278 liver transcripts (p < 0.01) that were enriched for the genes regulating hepatic stellate cells (HSCs) activation and hepatic fibrosis signaling. Our results suggest that IPA may have hepatoprotective potential because it is able to reduce cell adhesion, cell migration and mRNA gene expression of classical markers of HSCs activation in LX-2 cells (all p < 0.05). Conclusion: The association of circulating IPA with liver fibrosis and the ability of IPA to reduce activation of LX-2 cells suggests that IPA may have a therapeutic potential. Further molecular studies are needed to investigate the mechanisms how IPA can ameliorate hepatic fibrosis. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.
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| 3. |
- Schmidt, Florian M., et al.
(författare)
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Direct detection of acetylene in air by continuous wave cavity ring-down spectroscopy
- 2010
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Ingår i: Applied physics. B, Lasers and optics (Print). - : Springer Science and Business Media LLC. - 0946-2171 .- 1432-0649. ; 101:3, s. 671-682
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Tidskriftsartikel (refereegranskat)abstract
- Diode laser-based continuous wave cavity ring-down spectroscopy (cw-CRDS) in the near-infrared region has been used to measure the mixing ratio of acetylene (C(2)H(2)) in ambient air. Detection limits of 120 parts per trillion by volume (pptv) for 20 min and 340 pptv for 70 s acquisition time were achieved without sample pre-concentration, measuring on a C(2)H(2) absorption line at 6565.620 cm(-1) (similar to 1523 nm). Several indoor and outdoor air samples were collected at different locations in the Helsinki metropolitan area and analyzed using static-cell measurements. In addition, flow measurements of indoor and outdoor air have been performed continuously over several days with a time resolution of down to one minute. Baseline acetylene levels in the range of 0.4 to 3 parts per billion by volume (ppbv), with a maximum around midday and a minimum during the night, were measured. Sudden high mixing ratios of up to 60 ppbv were observed in outdoor air during daytime on a minute time scale. In general, the indoor mixing ratios were found to be higher than those in outdoor air. The acetylene levels correlated with the ambient CO levels and with outdoor temperature.
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| 4. |
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| 5. |
- Metsälä, Markus, et al.
(författare)
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Acetylene in breath : background levels and real-time elimination kinetics after smoking
- 2010
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Ingår i: Journal of Breath Research. - Bristol, UK : Institute of Physics Publishing (IOPP). - 1752-7155 .- 1752-7163. ; 4:4
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Tidskriftsartikel (refereegranskat)abstract
- We have measured the acetylene concentration in the exhaled breath of 40 volunteers (31 non-smokers, nine smokers) using near-infrared cavity ring-down spectroscopy. The acetylene levels were found to be the same as in ambient air for non-smokers, whereas elevated levels were observed for smokers. Real-time measurements with sub-second time resolution have been applied to measure the elimination kinetics of acetylene in breath after exposure to tobacco smoke. Three exponential time constants can be distinguished from the data and these can be used to define the residence times for different compartments, according to the multi-compartment model of the human body.
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| 7. |
- Schmidt, Florian M., et al.
(författare)
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Background levels and diurnal variations of hydrogen cyanide in breath and emitted from skin
- 2011
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Ingår i: Journal of Breath Research. - Bristol, UK : Institute of Physics Publishing (IOPP). - 1752-7163 .- 1752-7155. ; 5:4
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Tidskriftsartikel (refereegranskat)abstract
- The hydrogen cyanide (HCN) concentration in exhaled human breath and skin gas samples collected with different sampling techniques was measured using near-infrared cavity ring-down spectroscopy. The median baseline HCN concentrations in samples provided by 19 healthy volunteers 2-4 h after the last meal depended on the employed sampling technique: 6.5 parts per billion by volume (ppbv) in mixed (dead space and end-tidal) mouth-exhaled breath collected to a gas sampling bag, 3.9 ppbv in end-tidal mouth-exhaled breath, 1.3 ppbv in end-tidal nose-exhaled breath, 1.0 ppbv in unwashed skin and 0.6 ppbv in washed skin samples. Diurnal measurements showed that elevated HCN levels are to be expected in mouth-exhaled breath samples after food and drink intake, which suggests HCN generation in the oral cavity. The HCN concentrations in end-tidal nose-exhaled breath and skin gas samples were correlated, and it is concluded that these concentrations best reflect systemic HCN levels.
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| 9. |
- Vaittinen, Olavi, et al.
(författare)
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Exhaled breath biomonitoring using laser spectroscopy
- 2013
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Ingår i: Current Analytical Chemistry. - : Bentham Science Publishers Ltd.. - 1573-4110 .- 1875-6727. ; 9:3, s. 463-475
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Tidskriftsartikel (refereegranskat)abstract
- Biological monitoring usually relies on the collection of blood and urine samples. Although being non-invasive and providing an inextinguishable sampling pool, the analysis of exhaled breath is not well established. A gas phase measurement is, however, inherently simpler than the analysis of complex biological fluids, and modern methods have identified hundreds of volatile compounds in the breath of persons exposed to normal environmental concentrations. The most commonly deployed analytical techniques in breath analysis are gas chromatography combined with mass spectrometry (GC/MS) and other MS-based methods. Lately, also laser-based optical methods, such as cavity ring-down spectroscopy (CRDS), have emerged in the field. With such instruments, it is possible to accurately quantify the concentrations of volatiles in exhaled breath down to below part-per-billion (ppb) levels with sub-second time resolution. Laser spectroscopy thereby enables real-time investigations during and after exposure to exogenous chemicals. In general, depending on the sampling approach used, the measured levels of the breath compounds may vary significantly. It is therefore of importance to systematically study and account for the phenomena affecting the recorded concentrations, and subsequently select an appropriate sampling and measurement strategy. In Helsinki, we have used CRDS to study the background levels of hydrogen cyanide (HCN), ammonia (NH3) and acetylene (C2H2) in the exhaled breath of healthy volunteers. Different sampling techniques have been employed in an effort to standardize the breath sampling event. The realtime elimination kinetics of breath C2H2 after smoking has also been studied.
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