| 1. |
- Beck, Olof, et al.
(författare)
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Volumetric dried blood spots for determination of phosphatidylethanol: Validation of a liquid chromatography tandem masspectrometry method and clinical application
- 2024
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Ingår i: DRUG TESTING AND ANALYSIS. - 1942-7603 .- 1942-7611.
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Tidskriftsartikel (refereegranskat)abstract
- Phosphatidylethanol (PEth) measurement in whole blood samples is established as a specific alcohol biomarker with clinical and forensic applications. Establishment of dried blood spots (DBSs) as a specimen for PEth determination offers several advantages and was the focus of this work. A liquid chromatography tandem mass spectrometry method using a 96-well format for sample preparation was developed and validated. PEth was extracted from DBSs by using isopropanol containing PEth-d5 as internal standard. The blood sampling used a commercial volumetric DBS device having a phosholipase D inhibitor incorporated to stop continuous PEth formation. The method quantified PEth in the range of 0.05-10 mu mol/L, with a bias and imprecision of less than 15%. In a clinical study (n = 25) using fingerprick blood, the volumetric device offered more precise quantifications (CV 4.6%) compared with the Whatman 903 Protein Saver card device (CV 16.6%). In another clinical study (n = 48), the use of dried venous and capillary blood, and liquid venous blood was compared under real-life conditions with samples sent by postal service. The capillary and venous DBS samples gave identical results while the liquid blood gave slightly higher values. Calculation of elimination half-life (PEth 16:0/18:1) in 31 cases based on two consecutive samples with 2-9 days in between gave results (mean 6.2 days) that agree with literature but several cases with values over 10 days. In conclusion, this study demonstrates that volumetric DBS is a valid specimen for determination of PEth blood concentrations, offering several advantages. Phosphatidylethanol, a specific alcohol biomarker, measured in dried blood spots was the focus of this work. A liquid chromatography tandem mass spectrometry method was developed, validated, and applied. The blood sampling used a volumetric DBS device. The volumetric device gave accurate and precise quantifications and the dried capillary blood gave the same results as that of venous blood. image
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| 2. |
- Charlier, R, et al.
(författare)
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Water Influence on Bearing Capacity and Pavement Performance : Field Observations
- 2009
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Ingår i: Water in Road Structures. - Dordrecht : Springer. - 9781402085611 ; , s. 175-192
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Bokkapitel (refereegranskat)abstract
- This chapter presents a mechanical behaviour study, i.e. the bearing capacity as a function of the moisture degree. The field point of view is expressed and the chapter summarises a number of observations on road behaviour, in relation to variations of moisture. First, the road structure is recalled with respect to the mechanical analysis point of view. Then some observations on field under temperate climate, humid, are given. In a second step, the specific case of frost and thawing are discussed.
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| 3. |
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| 4. |
- Hermansson, Åke, et al.
(författare)
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Heat Transfer in Soils
- 2009
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Ingår i: Water in Road Structures. - Dordrecht : Springer. ; , s. 69-79
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Bokkapitel (refereegranskat)abstract
- Temperature highly affects pavement performance. High and low temperatures not only affects the viscosity of asphalt concrete but also has an impact on the moisture flow within pavements. At temperatures below 0°C the freezing of pavements dramatically changes the permeability and frost action might occur forcing water to flow upwards to the freezing front resulting in frost heave and other pavement distress.
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| 5. |
- Hober, Andreas, et al.
(författare)
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Rapid and sensitive detection of SARS-CoV-2 infection using quantitative peptide enrichment LC-MS analysis
- 2021
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Ingår i: eLIFE. - : eLIFE SCIENCES PUBL LTD. - 2050-084X. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Reliable, robust, large-scale molecular testing for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is essential for monitoring the ongoing coronavirus disease 2019 (COVID-19) pandemic. We have developed a scalable analytical approach to detect viral proteins based on peptide immuno-affinity enrichment combined with liquid chromatography-mass spectrometry (LC-MS). This is a multiplexed strategy, based on targeted proteomics analysis and read-out by LC-MS, capable of precisely quantifying and confirming the presence of SARS-CoV-2 in phosphate-buffered saline (PBS) swab media from combined throat/nasopharynx/saliva samples. The results reveal that the levels of SARS-CoV-2 measured by LC-MS correlate well with their correspondingreal-time polymerase chain reaction (RT-PCR) read-out (r = 0.79). The analytical workflow shows similar turnaround times as regular RT-PCR instrumentation with a quantitative read-out of viral proteins corresponding to cycle thresholds (Ct) equivalents ranging from 21 to 34. Using RT-PCR as a reference, we demonstrate that the LC-MS-based method has 100% negative percent agreement (estimated specificity) and 95% positive percent agreement (estimated sensitivity) when analyzing clinical samples collected from asymptomatic individuals with a Ct within the limit of detection of the mass spectrometer (Ct <= 30). These results suggest that a scalable analytical method based on LC-MS has a place in future pandemic preparedness centers to complement current virus detection technologies.
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| 6. |
- Schwieler, Lilly, et al.
(författare)
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A novel, robust method for quantification of multiple kynurenine pathway metabolites in the cerebrospinal fluid
- 2020
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Ingår i: Bioanalysis. - : Future Science Ltd. - 1757-6180 .- 1757-6199. ; 12:6, s. 379-392
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Tidskriftsartikel (refereegranskat)abstract
- Aim: Kynurenine metabolites are potential modulators of psychiatric disease. We aimed to develop a highly sensitive biochemical analysis of cerebrospinal fluid (CSF) tryptophan (TRP) metabolites, to investigate the stability of metabolites and to confirm our previous findings of aberrant CSF quinolinic acid (QUIN) and picolinic acid (PIC) in suicide attempters using this method. Methodology & results: Ten CSF TRP metabolites were analyzed with ultraperformance LC-MS/MS. The method showed small intra- and interassay variation. Metabolites were stable following freeze-thaw cycles. A decreased CSF PIC/QUIN ratio was found in suicide attempters. Conclusion: The feasibility of reliably determining CSF TRP metabolites were demonstrated, including separation of the two isomers PIC and nicotinic acid (NA) and the finding of a reduced PIC/QUIN ratio replicated in suicide attempters.
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| 7. |
- Trepci, Ada, et al.
(författare)
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Quantification of Plasma Kynurenine Metabolites Following One Bout of Sprint Interval Exercise
- 2020
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Ingår i: International Journal of Tryptophan Research. - : SAGE Publications. - 1178-6469. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- The kynurenine pathway of tryptophan degradation produces several neuroactive metabolites suggested to be involved in a wide variety of diseases and disorders, however, technical challenges in reliably detecting these metabolites hampers cross-comparisons. The main objective of this study was to develop an accurate, robust and precise bioanalytical method for simultaneous quantification of ten plasma kynurenine metabolites. As a secondary aim, we applied this method on blood samples taken from healthy subjects conducting 1 session of sprint interval exercise (SIE). It is well accepted that physical exercise is associated with health benefits and reduces risks of psychiatric illness, diabetes, cancer and cardiovascular disease, but also influences the peripheral and central concentrations of kynurenines. In line with this, we found that in healthy old adults (n = 10; mean age 64 years), levels of kynurenine increased 1 hour (P =.03) after SIE, while kynurenic acid (KYNA) concentrations were elevated after 24 hours (P =.02). In contrast, no significant changes after exercise were seen in young adults (n = 10; mean age 24 years). In conclusion, the described method performs well in reliably detecting all the analyzed metabolites in plasma samples. Furthermore, we also detected an age-dependent effect on the degree by which a single intense training session affects kynurenine metabolite levels.
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