| 41. |
- Eggers, Kai M., 1962-, et al.
(författare)
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Value of cardiac troponin I cutoff concentrations below the 99th percentile for clinical decision-making
- 2009
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Ingår i: Clinical Chemistry. - : Oxford University Press (OUP). - 0009-9147 .- 1530-8561. ; 55:1, s. 85-92
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The aim of this study was to evaluate factors influencing the 99th percentile for cardiac troponin I (cTnI) when this cutoff value is established on a highly sensitive assay, and to compare the value of this cutoff to that of lower cutoffs in the prognostic assessment of patients with coronary artery disease. METHODS: We used the recently refined Access AccuTnI assay (Beckman-Coulter) to assess the distribution of cTnI results in a community population of elderly individuals [PIVUS (Prospective Study of the Vasculature in Uppsala Seniors) study; n = 1005]. The utility of predefined cTnI cutoffs for risk stratification was then evaluated in 952 patients from the FRISC II (FRagmin and Fast Revascularization during InStability in Coronary artery disease) study at 6 months after these patients had suffered acute coronary syndrome. RESULTS: Selection of assay results from a subcohort of PIVUS participants without cardiovascular disease resulted in a decrease of the 99th percentile from 0.044 microg/L to 0.028 microg/L. Men had higher rates of cTnI elevation with respect to the tested thresholds. Whereas the 99th percentile cutoff was not found to be a useful prognostic indicator for 5-year mortality, both the 90th percentile (hazard ratio 3.1; 95% CI 1.9-5.1) and the 75th percentile (hazard ratio 2.8; 95% CI 1.7-4.7) provided useful prognostic information. Sex-specific cutoffs did not improve risk prediction. CONCLUSIONS: The 99th percentile of cTnI depends highly on the characteristics of the reference population from which it is determined. This dependence on the reference population may affect the appropriateness of clinical conclusions based on this threshold. However, cTnI cutoffs below the 99th percentile seem to provide better prognostic discrimination in stabilized acute coronary syndrome patients and therefore may be preferable for risk stratification.
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| 42. |
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| 43. |
- Eisen, A., et al.
(författare)
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High-Sensitivity Troponin I in Stable Patients with Atherosclerotic Disease in the TRA 2 degrees P - TIMI 50 Trial
- 2017
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Ingår i: Clinical Chemistry. - : Oxford University Press (OUP). - 0009-9147 .- 1530-8561. ; 63:1, s. 307-315
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Cardiac troponin I, measured with a high-sensitivity assay (hs-TnI), is well-established for risk prediction in acute coronary syndromes. However, its prognostic role in stable atherosclerotic disease, particularly for future myocardial infarction (MI), is less well defined. METHODS: We measured hs-TnI (Abbott ARCHITECT) in 15 833 patients with prior MI, ischemic stroke, or peripheral arterial disease from the placebo controlled Thrombin Receptor Antagonist in Secondary Prevention of Atherothrombotic Ischemic Events (TRA 2 degrees P) Thrombolysis in Myocardial Infarction (TIMI) 50 trial of the platelet inhibitor vorapaxar, excluding patients with recent MI (<30 days). hs-TnI was categorized into 5 groups based on the detection limit (1.9 ng/L), 99th percentile reference limit (26 ng/L), and tertiles in between (1.9-26 ng/L), as well as sex-specific reference limits. RESULTS: Higher hs-TnI concentration was associated with older age, male sex, and increased atherosclerosis burden. hs-TnI identified a graded 3-year risk of cardiovascular death, MI, or stroke from 5.0% to 18.6% (P < 0.001), driven by cardiovascular death and MI (P < 0.001). This risk was independent of established clinical risk indicators, B-type natriuretic peptide and C-reactive protein [adjusted hazard ratio 2.70 (95% CI, 1.96-3.71), P < 0.001 for hs-TnI >26 ng/L vs <1.9 ng/L]. In patients with prior MI, there was a pattern of greater absolute benefit with vorapaxar in patients with an increased hs-TnI (absolute risk difference 1.9% with hs-TnI >26 ng/L vs 0.3% with hs-TnI <1.9 ng/L; P interaction = 0.82). CONCLUSIONS: In stable patients with established atherosclerosis, hs-TnI concentrations effectively stratified the risk of new or recurrent cardiovascular (CV) events, in particular CV death and MI. High-risk patients with prior MI identified by increased hs-TnI had a substantial absolute improvement in net clinical outcome with vorapaxar. (C) 2016 American Association for Clinical Chemistry
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| 44. |
- El-Heliebi, Amin, et al.
(författare)
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In Situ Detection and Quantification of AR-V7, AR-FL, PSA, and KRAS Point Mutations in Circulating Tumor Cells
- 2018
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Ingår i: Clinical Chemistry. - : Oxford University Press (OUP). - 0009-9147 .- 1530-8561. ; 64:3, s. 536-546
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Liquid biopsies can be used in castration-resistant prostate cancer (CRPC) to detect androgen receptor splice variant 7 (AR-V7), a splicing product of the androgen receptor. Patients with AR-V7-positive circulating tumor cells (CTCs) have greater benefit of taxane chemotherapy compared with novel hormonal therapies, indicating a treatment-selection biomarker. Likewise, in those with pancreatic cancer (PaCa), KRAS mutations act as prognostic biomarkers. Thus, there is an urgent need for technology investigating the expression and mutation status of CTCs. Here, we report an approach that adds AR-V7 or KRAS status to CTC enumeration, compatible with multiple CTC-isolation platforms.METHODS: We studied 3 independent CTC-isolation devices (CellCollector, Parsortix, CellSearch) for the evaluation of AR-V7 or KRAS status of CTCs with in situ padlock probe technology. Padlock probes allow highly specific detection and visualization of transcripts on a cellular level. We applied padlock probes for detecting AR-V7, androgen receptor full length (AR-FL), and prostate-specific antigen (PSA) in CRPC and KRAS wildtype (wt) and mutant (mut) transcripts in PaCa in CTCs from 46 patients.RESULTS: In situ analysis showed that 71% (22 of 31) of CRPC patients had detectable AR-V7 expression ranging from low to high expression [1-76 rolling circle products (RCPs)/CTC]. In PaCa patients, 40% (6 of 15) had KRAS mut expressing CTCs with 1 to 8 RCPs/CTC. In situ padlock probe analysis revealed CTCs with no detectable cytokeratin expression but positivity for AR-V7 or KRAS mut transcripts.CONCLUSIONS: Padlock probe technology enables quantification of AR-V7, AR-FL, PSA, and KRAS mut/wt transcripts in CTCs. The technology is easily applicable in routine laboratories and compatible with multiple CTC-isolation devices.
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| 45. |
- Estampador, Angela C., et al.
(författare)
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Precision medicine in obesity and type 2 diabetes : The relevance of early-life exposures
- 2018
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Ingår i: Clinical Chemistry. - : American Association for Clinical Chemistry. - 0009-9147 .- 1530-8561. ; 64:1, s. 130-141
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Forskningsöversikt (refereegranskat)abstract
- BACKGROUND: Type 2 diabetes is highly prevalent and devastating. Obesity is a diabetogenic factor, driving insulin resistance and a compensatory demand for increased insulin secretion from the pancreatic cells; a failure to address this demand results in diabetes. Accordingly, primary and secondary prevention of obesity are at the core of diabetes prevention programs. The development of obesity and declining β-cell function often span many years or decades before diabetes is clinically manifest. Thus, characterizing the early-life process and risk factors that set disease trajectories may yield novel targets for early intervention and help improve the accuracy of prediction algorithms, factors germane to the emerging field of precision medicine. CONTENT: Here, we overview the concepts of precision medicine and fetal programming. We discuss the barriers to preventing obesity and type 2 diabetes in adulthood and present the rationale for considering early-life events in this context. In so doing, we discuss proof-of-concept studies and cutting-edge technological developments that are likely to transform current thinking on the etiology and pathogenesis of obesity and type 2 diabetes. We also review the factors hampering progress, including the success and failures of pregnancy intervention trials. SUMMARY: Obesity and type 2 diabetes are among the major health and economic burdens of our time. Defeating these diseases is likely to require life-course approaches, which may include aggressive interventions informed by biomarker profiling undertaken during early life.
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| 46. |
- Filges, Stefan, 1991, et al.
(författare)
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Digital Quantification of Chemical Oligonucleotide Synthesis Errors
- 2021
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Ingår i: Clinical Chemistry. - : Oxford University Press (OUP). - 0009-9147 .- 1530-8561. ; 67:10, s. 1384-1394
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Chemically synthesized oligonucleotides are vital to most nucleic acids-based technologies and several applications are sensitive to oligonucleotide sequence errors. However, it is challenging to identify and quantify the types and amount of errors in synthetic oligonucleotides. METHODS: We applied a digital sequencing approach using unique molecular identifiers to quantify errors in chemically synthesized oligonucleotides from multiple manufacturers with different synthesis strategies, purity grades, batches, and sequence context. RESULTS: We detected both deletions and substitutions in chemical oligonucleotide synthesis, but deletions were 7 times more common. We found that 97.2% of all analyzed oligonucleotide molecules were intact across all manufacturers and purity grades, although the number of oligonucleotide molecules with deletions ranged between 0.2% and 11.7% for different types. Different batches of otherwise identical oligonucleotide types also varied significantly, and batch effect can impact oligonucleotide quality more than purification. We observed a bias of increased deletion rates in chemically synthesized oligonucleotides toward the 5'-end for 1 out of 2 sequence configurations. We also demonstrated that the performance of sequencing assays depends on oligonucleotide quality. CONCLUSIONS: Our data demonstrate that manufacturer, synthesis strategy, purity, batch, and sequence context all contribute to errors in chemically synthesized oligonucleotides and need to be considered when choosing and evaluating oligonucleotides. High-performance oligonucleotides are essential in numerous molecular applications, including clinical diagnostics.
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| 47. |
- Floderus, Y, et al.
(författare)
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Variations in porphobilinogen and 5-aminolevulinic acid concentrations in plasma and urine from asymptomatic carriers of the acute intermittent porphyria gene with increased porphyrin precursor excretion
- 2006
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Ingår i: Clinical chemistry. - : Oxford University Press (OUP). - 0009-9147 .- 1530-8561. ; 52:4, s. 701-707
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Tidskriftsartikel (refereegranskat)abstract
- Background: The heme precursors porphobilinogen (PBG) and 5-aminolevulinic acid (ALA) accumulate during overt crises of acute intermittent porphyria (AIP), and high excretion of these metabolites often continues in the asymptomatic phase.Methods: We measured concentrations of PBG and ALA and investigated the correlation between these metabolites in plasma and urine in 10 asymptomatic AIP carriers with high excretion and in 5 healthy individuals. We quantified plasma concentrations with an HPLC–mass spectrometric method and urine concentrations with ion-exchange chromatography.Results: The mean (SD) plasma concentrations of PBG and ALA in the AIP carriers were 3.1 (1.0) and 1.7 (0.7) μmol/L, respectively. The mean 8-h urinary excretion amounts of PBG and ALA in the AIP carriers were 102 (25) and 56 (18) μmol, respectively, whereas the corresponding values for healthy individuals were 2.9 (0.7) and 9.3 (1.2) μmol. The correlations between PBG and ALA values in plasma and urine of the AIP carriers were 0.678 and 0.856, respectively. The mean PBG/ALA ratio was ∼2.0 in both plasma and urine for the AIP carriers and 0.3 in urine for the healthy individuals. The renal clearance rates for PBG and ALA were 71 (15) and 70 (13) mL/min, respectively.Conclusions: The described HPLC-mass spectrometric method enabled characterization of variations in plasma PBG and ALA in AIP carriers during an 8-h period. The renal clearances were similar for both metabolites. This method could be used to monitor AIP patients during treatment.
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| 48. |
- Fredriksson, Simon, et al.
(författare)
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Multiplexed proximity ligation assays to profile putative plasma biomarkers relevant to pancreatic and ovarian cancer
- 2008
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Ingår i: Clinical Chemistry. - : Oxford University Press (OUP). - 0009-9147 .- 1530-8561. ; 54:3, s. 582-589
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Sensitive methods are needed for biomarker discovery and validation. We tested one promising technology, multiplex proximity ligation assay (PLA), in a pilot study profiling plasma biomarkers in pancreatic and ovarian cancer. METHODS: We used 4 panels of 6- and 7-plex PLAs to detect biomarkers, with each assay consuming 1 mu L plasma and using either matched monoclonal antibody pairs or single batches of polyclonal antibody. Protein analytes were converted to unique DNA arnplicons by proximity ligation and subsequently detected by quantitative PCR. We profiled 18 pancreatic cancer cases and 19 controls and 19 ovarian cancer cases and 20 controls for the following proteins: a disintegrin and metalloprotease 8, CA-125, CA 19-9, carboxypeptidase A1, carcinoembryonic antigen, connective tissue growth factor, epidermal growth factor receptor, epithelial cell adhesion molecule, Her2, galectin-1, insulin-like growth factor 2, interleukin-1 alpha, interleukin-7, mesothelin, macrophage migration inhibitory factor, osteopontin, secretory leukocyte peptidase inhibitor, tumor necrosis factor a, vascular endothelial growth factor, and chitinase 3-like 1. Probes for CA-125 were present in 3 of the multiplex panels. We measured plasma concentrations of the CA-125-mesothelin complex by use of a triple-specific PLA with 2 ligation events among 3 probes. RESULTS: The assays displayed consistent measurements of CA-125 independent of which other markers were simultaneously detected and showed good correlation with Luminex data. In comparison to literature reports, we achieved expected results for other putative markers. CONCLUSION: Multiplex PLA using either matched monoclonal antibodies or single batches of polyclonal. antibody should prove useful for identifying and validating sets of putative disease biomarkers and finding. multimarker panels.
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| 49. |
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| 50. |
- Geistanger, Andrea, et al.
(författare)
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Statistical methods for monitoring the relationship between the IFCC reference measurement procedure for hemoglobin A(1c) and the designated comparison methods in the United States, Japan, and Sweden
- 2008
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Ingår i: Clinical Chemistry. - : American Association for Clinical Chemistry. - 0009-9147 .- 1530-8561. ; 54:8, s. 1379-1385
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The American Diabetes Association (ADA)/European Association for the Study of Diabetes (EASD)/International Diabetes Federation GDFAFCC Consensus Statement on the worldwide standardization of HbA(1c) states that"...[HbA(1c)] results are to be reported world-wide in IFCC units...and derived NGSP units...,using the IFCC-NGSP master equation." METHODS: We describe statistical methods to evaluate and monitor the relationships as expressed in master equations (MEs) between the IFCC Reference Measurement procedure (IFCC-RM) and designated comparison methods (DCMs) [US National Glycohemoglobin Standardization Program (NGSP), Japanese Diabetes Society/Japanese Society for Clinical Chemistry (JDS/JSCC), and Mono-S in Sweden]. We applied these statistics, including uncertainty calculations, to 12 studies in which networks of reference laboratories participated, operating the IFCC-RM and DCMs. RESULTS: For NGSP and Mono-S, slope, intercept, and derived percentage HbA(1c) at the therapeutic target show compliance with the respective MEs in all 12 studies. For JDS/JSCC, a slight deviation is seen in slope and derived percentage HbA(1c) in 2 of the 12 studies. Using the MEs, the uncertainty in an assigned value increases from 0.42 mmol/mol HbA(1c) (IFCC-RM) to 0.47 (NGSP), 0.49 (JDS/JSCC), and 0.51 (Mono-S). CONCLUSIONS: We describe sound statistical methods for the investigation of relations between networks of reference laboratories. Application of these statistical methods to the relationship between the JFCC-RM and DCMs in the US, Japan, and Sweden shows that they are suitable for the purpose, and the results support the applicability of the ADA/EASD/lDF/lFCC Consensus Statement on HbA1c measurement. (C) 2008 American Association for Clinical Chemistry.
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