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- Bowden, John A., et al.
(författare)
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Harmonizing lipidomics : NIST interlaboratory comparison exercise for lipidomics using SRM 1950-Metabolites in Frozen Human Plasma
- 2017
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Ingår i: Journal of Lipid Research. - 0022-2275 .- 1539-7262. ; 58:12, s. 2275-2288
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Tidskriftsartikel (refereegranskat)abstract
- As the lipidomics field continues to advance, self-evaluation within the community is critical. Here, we performed an interlaboratory comparison exercise for lipidomics using Standard Reference Material (SRM) 1950-Metabolites in Frozen Human Plasma, a commercially available reference material. The interlaboratory study comprised 31 diverse laboratories, with each laboratory using a different lipidomics workflow. A total of 1,527 unique lipids were measured across all laboratories and consensus location estimates and associated uncertainties were determined for 339 of these lipids measured at the sum composition level by five or more participating laboratories. These evaluated lipids detected in SRM 1950 serve as community-wide benchmarks for intra-and interlaboratory quality control and method validation. These analyses were performed using nonstandardized laboratory-independent workflows. The consensus locations were also compared with a previous examination of SRM 1950 by the LIPID MAPS consortium.jlr While the central theme of the interlaboratory study was to provide values to help harmonize lipids, lipid mediators, and precursor measurements across the community, it was also initiated to stimulate a discussion regarding areas in need of improvement.
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- Castillo Leon, Jaime, et al.
(författare)
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Glutamate detection from nerve cells using a planar electrodes array integrated in a microtiter plate
- 2005
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Ingår i: Biosensors & Bioelectronics. - : Elsevier BV. - 1873-4235 .- 0956-5663. ; 20:10, s. 2116-2119
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Tidskriftsartikel (refereegranskat)abstract
- There is an increasing interest in new strategies for replacing animal tests in research. The use of cell cultures and integrated electrodes is seen as a promising alternative that could potentially solve this problem. In this work, we present a L-glutamate sensor based on a bienzyme redox hydrogel, capable of detecting the release of this excitatory neurotransmitter from adherently growing cells upon stimulation. The low working potential required for the operation of the sensor decreases the possibility of interference by easily oxidizable compounds always present in complex biological samples. A low detection limit of 0.5 mu M L-glutamate, a response time of about 35 s, and a linear range of up to 60 mu M are the main characteristics of the sensor. The system has been successfully employed to monitor the release of L-glutamate from HN10 and C6 cells upon stimulation with K+-ions. The developed integrated electrochemical platform will be used in future for drug screening and potentially for replacing animal models in neurological experiments.
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- Castillo Leon, Jaime, et al.
(författare)
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Simultaneous detection of the release of glutamate and nitric oxide from adherently growing cells using an array of glutamate and nitric oxide selective electrodes
- 2005
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Ingår i: Biosensors & Bioelectronics. - : Elsevier BV. - 1873-4235 .- 0956-5663. ; 20:8, s. 1559-1565
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Tidskriftsartikel (refereegranskat)abstract
- The simultaneous detection of nitric oxide and glutamate using an array of individually addressable electrodes, in which the individual electrodes in the array were suitably modified with a highly sensitive nitric oxide sensing chemistry or a glutamate oxidase/redox hydrogel-based glutamate biosensor is presented. In a sequence of modification steps one of the electrodes was covered first with a positively charged Ni porphyrin entrapped into a negatively charged electrodeposition paint followed by the manual modification of the second working electrode by a bienzyme sensor architecture based on crosslinked redox hydrogels with entrapped peroxidase and glutamate oxidase. Adherently growing C6-glioma cells were grown on membrane inserts and placed in close distance to the modified sensor surfaces. The current responses recorded at each electrode after stimulation of glutamate and NO release by means of K+ and bradykinin clearly demonstrate the ability of the individual electrode in the array to detect the analyte towards which its sensitivity and selectivity was targeted without interference from the neighbouring electrode or other analytes present in the test mixture.
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- Chen, X. X., et al.
(författare)
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Traditional earth-abundant coal as new energy materials to catalyze the oxygen reduction reaction in alkaline solution
- 2016
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Ingår i: Electrochimica Acta. - : Elsevier BV. - 0013-4686. ; 211, s. 568-575
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Tidskriftsartikel (refereegranskat)abstract
- Coal is an earth-abundant energy resource, however, its direct combustion results in serious environmental pollution. Therefore, it becomes important to design value-added products from coal and to maximize its value chain. Herein, brown coal was used to develop non-precious metal catalysts for the oxygen reduction reaction (ORR) in fuel cells as green energy conversion systems. The brown coal was first pretreated with different acids, followed by N-doping at 800 degrees C in a stream of NH3. A trace amount of Fe was further added to improve the electrocatalytic performance of the prepared catalyst towards ORR. The prepared coal-derived N-doped carbon further modified with 0.5% Fe exhibited onset potential of 0.92 V vs. RHE at a current density of -0.1 mA cm(-2) and a predominantly 4-electron transfer pathway of oxygen to water in 0.1 M NaOH, which was evaluated by RDE and RRDE. The prepared electrocatalysts were further characterized by elemental analysis, XRD, Raman and XPS. The results suggest that the coal-derived ORR catalyst have convoluted graphitic and amorphous carbon structures. The N-content increased after acid-pretreatment and subsequent functionalization with nitrogen, while it slightly decreased after Fe incorporation apparently due to coordination of Fe with N. ORR activity enhancement after the incorporation of Fe is expected to mainly arise from a synergetic effect involving the interaction of Fe with N groups distributed in the carbon matrix. (C) 2016 Elsevier Ltd. All rights reserved.
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- Gaspar, S., et al.
(författare)
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A method for the design and study of enzyme microstructures formed by means of a flow-through microdispenser
- 2001
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Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 1520-6882 .- 0003-2700. ; 73:17, s. 4254-4261
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Tidskriftsartikel (refereegranskat)abstract
- Micrometer-sized enzyme grids were fabricated on gold surfaces using a novel method based on a flow-through microdispenser. The method involves dispensing very small droplets of enzyme solution (similar to 100 pL) during the concomitant relative movement of a gold substrate with respect to the nozzle of a microdispenser, resulting in enzyme patterns with a line width of similar to 100 mum. Different immobilization methods have been evaluated, yielding either enzyme monolayers using functionalized self-assembled thiol monolayers for covalent binding of the enzyme or enzyme multilayers by cross-linking or entrapping the enzymes in a polymer film. The latter immobilization techniques allow the formation of coupled multienzyme structures. On the basis of this feature, coupled bienzyme (glucose oxidase and catalase) or three-enzyme (alpha -glucosidase, mutarotase, and glucose oxidase) microstructures consisting of line patterns of one enzyme intersecting with the patterned lines of the other enzyme(s) were fabricated. By means of scanning electrochemical microscopy (SECM) operated in the generator-collector mode, the enzyme microstructures and their integrity were visualized using the localized detection of enzymatically produced/consumed H2O2. A calibration curve for glucose could be obtained by subsequent SECM line scans over a glucose oxidase microstructure for increasing glucose concentrations, demonstrating the possibility of obtaining localized quantitative data from the prepared microstructures. Possible applications of these enzyme microstructures for multianalyte detection and interference elimination and for screening of different biosensor configurations are highlighted.
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- Heyckendorf, J, et al.
(författare)
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Prediction of anti-tuberculosis treatment duration based on a 22-gene transcriptomic model
- 2021
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Ingår i: The European respiratory journal. - : European Respiratory Society (ERS). - 1399-3003 .- 0903-1936. ; 58:3
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Tidskriftsartikel (refereegranskat)abstract
- The World Health Organization recommends standardised treatment durations for patients with tuberculosis (TB). We identified and validated a host-RNA signature as a biomarker for individualised therapy durations for patients with drug-susceptible (DS)- and multidrug-resistant (MDR)-TB.MethodsAdult patients with pulmonary TB were prospectively enrolled into five independent cohorts in Germany and Romania. Clinical and microbiological data and whole blood for RNA transcriptomic analysis were collected at pre-defined time points throughout therapy. Treatment outcomes were ascertained by TBnet criteria (6-month culture status/1-year follow-up). A whole-blood RNA therapy-end model was developed in a multistep process involving a machine-learning algorithm to identify hypothetical individual end-of-treatment time points.Results50 patients with DS-TB and 30 patients with MDR-TB were recruited in the German identification cohorts (DS-GIC and MDR-GIC, respectively); 28 patients with DS-TB and 32 patients with MDR-TB in the German validation cohorts (DS-GVC and MDR-GVC, respectively); and 52 patients with MDR-TB in the Romanian validation cohort (MDR-RVC). A 22-gene RNA model (TB22) that defined cure-associated end-of-therapy time points was derived from the DS- and MDR-GIC data. The TB22 model was superior to other published signatures to accurately predict clinical outcomes for patients in the DS-GVC (area under the curve 0.94, 95% CI 0.9–0.98) and suggests that cure may be achieved with shorter treatment durations for TB patients in the MDR-GIC (mean reduction 218.0 days, 34.2%; p<0.001), the MDR-GVC (mean reduction 211.0 days, 32.9%; p<0.001) and the MDR-RVC (mean reduction of 161.0 days, 23.4%; p=0.001).ConclusionBiomarker-guided management may substantially shorten the duration of therapy for many patients with MDR-TB.
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