| 1. |
- Ahonen, Linda, et al.
(författare)
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Targeted Clinical Metabolite Profiling Platform for the Stratification of Diabetic Patients
- 2019
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Ingår i: Metabolites. - : MDPI. - 2218-1989 .- 2218-1989. ; 9:9
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Tidskriftsartikel (refereegranskat)abstract
- Several small molecule biomarkers have been reported in the literature for prediction and diagnosis of (pre)diabetes, its co-morbidities, and complications. Here, we report the development and validation of a novel, quantitative method for the determination of a selected panel of 34 metabolite biomarkers from human plasma. We selected a panel of metabolites indicative of various clinically-relevant pathogenic stages of diabetes. We combined these candidate biomarkers into a single ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method and optimized it, prioritizing simplicity of sample preparation and time needed for analysis, enabling high-throughput analysis in clinical laboratory settings. We validated the method in terms of limits of detection (LOD) and quantitation (LOQ), linearity (R2), and intra- and inter-day repeatability of each metabolite. The method's performance was demonstrated in the analysis of selected samples from a diabetes cohort study. Metabolite levels were associated with clinical measurements and kidney complications in type 1 diabetes (T1D) patients. Specifically, both amino acids and amino acid-related analytes, as well as specific bile acids, were associated with macro-albuminuria. Additionally, specific bile acids were associated with glycemic control, anti-hypertensive medication, statin medication, and clinical lipid measurements. The developed analytical method is suitable for robust determination of selected plasma metabolites in the diabetes clinic.
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| 2. |
- Allard, Erik, 1976-
(författare)
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Metabolic Studies with Liquid Separation Coupled to Mass Spectrometry
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Metabolism is the sum of all chemical processes with the purpose to maintain life, as well as enable reproduction, in a living organism. Through the study of metabolism, increased understanding of pharmacological mechanisms and diseases can be achieved. This thesis describes several ways of doing so, including targeted analysis of selected metabolites and investigations of systematic metabolic differences between selected groups through pattern recognition. A method for exploring metabolic patterns in urine samples after intake of coffee or tea was developed. The methodology was later used with the aim to find biomarkers for prostate cancer and urinary bladder cancer. Furthermore, a fully automated quantitative method was developed for concentration measurements of the double prodrug ximelagatran and its metabolites in pig liver. The method was then used to study the roll of active transporters in pig liver cells. Moreover, a fundamental study was conducted to investigate how monitoring of small, doubly charged analytes can improve the limit of detection and precision in a quantitative method. The techniques used for the experiments were liquid separation coupled to electrospray mass spectrometry. Extra efforts were made to make the separation and the ionization as compatible as possible to each other for increased quality of the collected data.
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| 3. |
- Jäntti, Sirkku E., et al.
(författare)
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Steroid and steroid glucuronide profiles in urine during pregnancy determined by liquid chromatography-electrospray ionization-tandem mass spectrometry
- 2013
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Ingår i: Analytica Chimica Acta. - : Elsevier. - 0003-2670 .- 1873-4324. ; 802, s. 56-66
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Tidskriftsartikel (refereegranskat)abstract
- An ultra performance liquid chromatography-electrospray ionization-tandem mass spectrometry (UPLC-MS/MS) method was developed for the analysis of steroids and their glucuronides in urine samples. The method provides high sensitivity and fast analysis, as both steroids and their glucuronides can be analyzed directly without hydrolysis or complex sample preparation. The method was applied in profiling of targeted and nontargeted steroids and steroid glucuronides during pregnancy. The concentrations of 11 of 27 targeted steroids and steroid glucuronides and the concentrations of 25 nontargeted steroid glucuronides increased about 10-400 fold during the pregnancy. The concentrations of most of these 36 compounds began to increase in the first days of the pregnancy, increased gradually during the pregnancy, achieved a maximum in late pregnancy, and decreased sharply after delivery. Exceptionally, the concentrations of allopregnanolone and 17-hydroxypregnenolone started to increase later than those of the other steroids. Moreover, the concentrations of E2 glucuronides began to decrease one week before the delivery, in contrast to most of the steroids and steroid glucuronides, whose concentrations dropped sharply during the delivery. Concentrations of 34 compounds decreased noticeably when the subject was on sick leave owing a series of painful contractions. The results suggest that steroids and especially steroid glucuronides may provide a valuable diagnostic tool to follow the course of pregnancy.
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| 4. |
- Moravcová, Dana, et al.
(författare)
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Separation of nucleobases, nucleosides, and nucleotides using two zwitterionic silica-based monolithic capillary columns coupled with tandem mass spectrometry
- 2014
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Ingår i: Journal of Chromatography A. - : Elsevier. - 0021-9673 .- 1873-3778. ; 1373, s. 90-96
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Tidskriftsartikel (refereegranskat)abstract
- The capability of employing synthesized zwitterionic silica-based monolithic capillary columns (140 mm x 0.1 mm) for separation of highly polar and hydrophilic nucleobases, nucleosides, and nucleotides in hydrophilic interaction chromatography is reported. The suitability of the columns for on-line conjunction with electrospray tandem mass spectrometry was explored. Our results show that the grafted layer of zwitterionic monomer ([2-(methacryloyloxy)ethyl]-dimethyl-(3-sulfopropyl)-ammonium hydroxide or 2-methaciyloyloxyethyl phosphorylcholine) on the silica monolithic surface significantly improved the separation selectivity and reproducibility, as compared to the bare silica monolith. The stepwise elution from 90% to 70% of acetonitrile enabled separation of a complex sample mixture containing 21 compounds with a total analysis time less than 40 min.
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| 5. |
- Suominen, Tina, et al.
(författare)
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Determination of Serotonin and Dopamine Metabolites in Human Brain Microdialysis and Cerebrospinal Fluid Samples by UPLC-MS/MS : Discovery of Intact Glucuronide and Sulfate Conjugates
- 2013
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 8:6, s. e68007-
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Tidskriftsartikel (refereegranskat)abstract
- An UPLC-MS/MS method was developed for the determination of serotonin (5-HT), dopamine (DA), their phase I metabolites 5-HIAA, DOPAC and HVA, and their sulfate and glucuronide conjugates in human brain microdialysis samples obtained from two patients with acute brain injuries, ventricular cerebrospinal fluid (CSF) samples obtained from four patients with obstructive hydrocephalus, and a lumbar CSF sample pooled mainly from patients undergoing spinal anesthesia in preparation for orthopedic surgery. The method was validated by determining the limits of detection and quantification, linearity, repeatability and specificity. The direct method enabled the analysis of the intact phase II metabolites of 5-HT and DA, without hydrolysis of the conjugates. The method also enabled the analysis of the regioisomers of the conjugates, and several intact glucuronide and sulfate conjugates were identified and quantified for the first time in the human brain microdialysis and CSF samples. We were able to show the presence of 5-HIAA sulfate, and that dopamine-3-O-sulfate predominates over dopamine-4-O-sulfate in the human brain. The quantitative results suggest that sulfonation is a more important phase II metabolism pathway than glucuronidation in the human brain.
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