| 1. |
- Chinnasamy, Thiruppathiraja, et al.
(author)
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Point-of-Care Vertical Flow Allergen Microarray Assay : Proof of Concept
- 2014
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In: Clinical Chemistry. - : Oxford University Press (OUP). - 0009-9147 .- 1530-8561. ; 60:9, s. 1209-1216
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Journal article (peer-reviewed)abstract
- BACKGROUND: Sophisticated equipment, lengthy protocols, and skilled operators are required to perform protein microarray-based affinity assays. Consequently, novel tools are needed to bring biomarkers and biomarker panels into clinical use in different settings. Here, we describe a novel paper-based vertical flow microarray (VFM) system with a multiplexing capacity of at least 1480 microspot binding sites, colorimetric readout, high sensitivity, and assay time of < 10 min before imaging and data analysis. METHOD: Affinity binders were deposited on nitrocellulose membranes by conventional microarray printing. Buffers and reagents were applied vertically by use of a flow controlled syringe pump. As a clinical model system, we analyzed 31 precharacterized human serum samples using the array system with 10 allergen components to detect specific IgE reactivities. We detected bound analytes using gold nanoparticle conjugates with assay time of <= 10 min. Microarray images were captured by a consumer-grade flatbed scanner. RESULTS: A sensitivity of 1 ng/mL was demonstrated with the VFM assay with colorimetric readout. The reproducibility (CV) of the system was < 14%. The observed concordance with a clinical assay, Immuno-CAP, was R-2 = 0.89 (n = 31). CONCLUSIONS: In this proof-of-concept study, we demonstrated that the VFM assay, which combines features from protein microarrays and paper-based colorimetric systems, could offer an interesting alternative for future highly multiplexed affinity point-of-care testing.
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| 2. |
- Ebeling Barbier, Charlotte, et al.
(author)
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Cardiac Troponin I Associated with the Development of Unrecognized Myocardial Infarctions Detected with MRI
- 2014
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In: Clinical Chemistry. - : Oxford University Press (OUP). - 0009-9147 .- 1530-8561. ; 60:10, s. 1327-1335
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Journal article (peer-reviewed)abstract
- BACKGROUND:Late enhancement MRI (LE-MRI) and cardiac troponin I (cTnI) are sensitive methods to detect subclinical myocardial injury. We sought to investigate the relation between plasma concentrations of cTnI measured with a high-sensitivity assay (hs-cTnI) and the development of unrecognized myocardial infarctions (UMIs) detected with LE-MRI.METHODS:After approval from the ethics committee and written informed consent were obtained, LE-MRI was performed on 248 randomly selected community-living 70-year-old volunteers and hs-cTnI was determined with a highly sensitive premarket assay. Five years later these individuals were invited to a second LE-MRI, and 176 of them (82 women, 94 men), who did not have a hospital diagnosis of MI, constitute the present study population. LE-MR images were analyzed by 2 radiologists independently and in a consensus reading, blinded to any information on previous disease or assessments.RESULTS:New or larger UMIs were detected in 37 participants during follow-up. Plasma concentrations of hs-cTnI at 70 years of age, which were mainly within what is considered to be the reference interval, were related to new or larger UMIs at 75 years of age with an odds ratio of 1.98 per 1 unit increase in ln-transformed cTnI (95% CI, 1.17-3.35; P = 0.010). Plasma concentrations of hs-cTnI at 70 years of age were associated with the volumes of the UMIs detected at 75 years of age (P = 0.028).CONCLUSIONS:hs-cTnI in 70-year-old community-living women and men was associated with the development of MRI-detected UMIs within 5 years.
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| 3. |
- Grubb, Anders, et al.
(author)
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Generation of a new cystatin C-based estimating equation for glomerular filtration rate by use of 7 assays standardized to the international calibrator
- 2014
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In: Clinical Chemistry. - : Oxford University Press (OUP). - 0009-9147 .- 1530-8561. ; 60:7, s. 974-986
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Journal article (peer-reviewed)abstract
- BACKGROUND:Many different cystatin C-based equations exist for estimating glomerular filtration rate. Major reasons for this are the previous lack of an international cystatin C calibrator and the nonequivalence of results from different cystatin C assays.METHODS:Use of the recently introduced certified reference material, ERM-DA471/IFCC, and further work to achieve high agreement and equivalence of 7 commercially available cystatin C assays allowed a substantial decrease of the CV of the assays, as defined by their performance in an external quality assessment for clinical laboratory investigations. By use of 2 of these assays and a population of 4690 subjects, with large subpopulations of children and Asian and Caucasian adults, with their GFR determined by either renal or plasma inulin clearance or plasma iohexol clearance, we attempted to produce a virtually assay-independent simple cystatin C-based equation for estimation of GFR.RESULTS:We developed a simple cystatin C-based equation for estimation of GFR comprising only 2 variables, cystatin C concentration and age. No terms for race and sex are required for optimal diagnostic performance. The equation, [Formula: see text] is also biologically oriented, with 1 term for the theoretical renal clearance of small molecules and 1 constant for extrarenal clearance of cystatin C.CONCLUSIONS:A virtually assay-independent simple cystatin C-based and biologically oriented equation for estimation of GFR, without terms for sex and race, was produced.
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| 4. |
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| 5. |
- Leinenbach, Andreas, et al.
(author)
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Mass spectrometry-based candidate reference measurement procedure for quantification of amyloid-β in cerebrospinal fluid.
- 2014
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In: Clinical chemistry. - : Oxford University Press (OUP). - 1530-8561 .- 0009-9147. ; 60:7, s. 987-94
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Journal article (peer-reviewed)abstract
- Cerebrospinal fluid (CSF) amyloid-β (Aβ42) is a well-established biomarker for Alzheimer disease. Several immunoassays for Aβ42 exist but differ in absolute concentrations and may suffer from matrix interference, thereby hampering interlaboratory comparisons and the use of general cutoff levels. Together with the IFCC Working Group on CSF Proteins, we developed a candidate reference measurement procedure (RMP) for Aβ42.
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| 6. |
- Starnberg, Karin, et al.
(author)
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Revision of the troponin T release mechanism from damaged human myocardium.
- 2014
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In: Clinical chemistry. - : Oxford University Press (OUP). - 1530-8561 .- 0009-9147. ; 60:8, s. 1098-104
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Journal article (peer-reviewed)abstract
- Cardiac troponin T (cTnT) is released from damaged heart tissue in patients with acute myocardial infarction. It is presumed that most cTnT is tightly bound and released following the degradation of myofibrils in necrotic cardiomyocytes, resulting in sustained increases in circulating cTnT. Evidence of a large irreversibly bound fraction is based on the inability to extract most cTnT from cardiac tissue in cold low-salt extraction buffers.
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| 7. |
- Sävblom, Charlotta, et al.
(author)
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Genetic variation in KLK2 and KLK3 is associated with concentrations of hK2 and PSA in serum and seminal plasma in young men
- 2014
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In: Clinical Chemistry. - : American Association for Clinical Chemistry. - 0009-9147 .- 1530-8561. ; 60:3, s. 490-499
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Journal article (peer-reviewed)abstract
- BACKGROUND: Genetic variants in KLK2 and KLK3 have been associated with increased serum concentrations of their encoded proteins, human kallikrein-related peptidase 2 (hK2) and prostate-specific antigen (PSA), and with prostate cancer in older men. Low PSA concentrations in seminal plasma (SP) have been associated with low sperm motility. To evaluate whether KLK2 and KLK3 genetic variants affect physiological prostatic secretion, we studied the association of SNPs with hK2 and PSA concentrations in SP and serum of young, healthy men.METHODS: Leukocyte DNA was extracted from 303 male military conscripts (median age 18.1 years). Nine SNPs across KLK2-KLK3 were genotyped. We measured PSA and hK2 in SP and serum using immunofluorometric assays. The association of genotype frequencies with hK2 and PSA concentrations was tested with the Kruskal-Wallis test.RESULTS: Four KLK2 SNPs (rs198972, rs198977, rs198978, and rs80050017) were strongly associated with hK2 concentrations in SP and serum, with individuals homozygous for the major alleles having 3- to 7-fold higher concentrations than the intermediate concentrations found in other homozygotes and heterozygotes (all P < 0.001). Three of these SNPs were significantly associated with percentage of free PSA (%fPSA) in serum (all P < 0.007). Three KLK3 SNPs showed associations with PSA in SP, and the rs1058205 SNP was associated with total PSA in serum (P = 0.001) and %fPSA (P = 0.015).CONCLUSIONS: Associations observed in young, healthy men between the SP and serum concentrations of hK2 and PSA and several genetic variants in KLK2 and KLK3 could be useful to refine models of PSA cutoff values in prostate cancer testing.
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| 8. |
- Sävblom, Charlotta, et al.
(author)
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Genetic Variation in KLK2 and KLK3 Is Associated with Concentrations of hK2 and PSA in Serum and Seminal Plasma in Young Men
- 2014
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In: Clinical Chemistry. - : Oxford University Press (OUP). - 0009-9147 .- 1530-8561. ; 60:3, s. 490-499
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Journal article (peer-reviewed)abstract
- BACKGROUND: Genetic variants in KLK2 and KLK3 have been associated with increased serum concentrations of their encoded proteins, human kallikrein-related peptidase 2 (hK2) and prostate-specific antigen (PSA), and with prostate cancer in older men. Low PSA concentrations in seminal plasma (SP) have been associated with low sperm motility. To evaluate whether KLK2 and KLK3 genetic variants affect physiological prostatic secretion, we studied the association of SNPs with hK2 and PSA concentrations in SP and serum of young, healthy men. METHODS: Leukocyte DNA was extracted from 303 male military conscripts (median age 18.1 years). Nine SNPs across KLK2-KLK3 were genotyped. We measured PSA and hK2 in SP and serum using immunofluorometric assays. The association of genotype frequencies with hK2 and PSA concentrations was tested with the Kruskal-Wallis test. RESULTS: Four KLK2 SNPs (rs198972, rs198977, rs198978, and rs80050017) were strongly associated with hK2 concentrations in SP and serum, with individuals homozygous for the major alleles having 3-to 7-fold higher concentrations than the intermediate concentrations found in other homozygotes and heterozygotes (all P < 0.001). Three of these SNPs were significantly associated with percentage of free PSA (% fPSA) in serum (all P < 0.007). Three KLK3 SNPs showed associations with PSA in SP, and the rs1058205 SNP was associated with total PSA in serum (P = 0.001) and % fPSA (P = 0.015). CONCLUSIONS: Associations observed in young, healthy men between the SP and serum concentrations of hK2 and PSA and several genetic variants in KLK2 and KLK3 could be useful to refine models of PSA cutoff values in prostate cancer testing. (C) 2013 American Association for Clinical Chemistry
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| 9. |
- Wang, HY, et al.
(author)
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Profiling plasma microRNA in nasopharyngeal carcinoma with deep sequencing
- 2014
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In: Clinical chemistry. - : Oxford University Press (OUP). - 1530-8561 .- 0009-9147. ; 60:5, s. 773-782
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Journal article (peer-reviewed)abstract
- BACKGROUNDThe goal of this study was to establish a plasma microRNA profile by use of next-generation sequencing that could aid in assessment of patient prognosis in nasopharyngeal carcinoma (NPC).METHODSTwo panels of NPC patients and healthy controls (HCs) were recruited for this study. We used deep sequencing to screen plasma microRNAs. Differentially expressed microRNAs were verified by quantitative real-time PCR (qPCR). Kaplan–Meier survival analysis with the log-rank test was used to compare overall survival (OS) and progression-free survival (PFS) between groups.RESULTSTwenty-three plasma miRNAs with differential expression levels were selected for qPCR analysis on an independent set including 100 NPC patients and 55 HCs. NPC patients with low concentrations of miR-483–5p and miR-103 had better prognosis for 5-year OS than those with high concentrations (87.5% vs 55.8%, P < 0.001; 80.9% vs 62.3%, P = 0.031). Those with low concentrations of miR-29a and let-7c had poorer prognosis (54.8% vs 82.8%, P = 0.002; 56.3% vs 84.6%, P = 0.001). A 3-signature miRNA integrated with clinical stage was further identified in an independent set. We calculated a prognostic index score and classified patients into low-, medium-, and high-risk groups. Five-year OS among the 3 groups was significantly different (90.9%, 66.7%, and 23.8%; P < 0.001). By multivariate analysis, a high-risk score was the most significantly unfavorable prognostic factor independent of other clinical variables (P < 0.001, hazard ratio = 15.1, 95% CI = 5.2–43.9).CONCLUSIONSDifferentially expressed plasma miRNAs as identified by next-generation sequencing can be helpful for predicting survival in NPC patients.
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