| 1. |
- Alehagen, Urban, et al.
(författare)
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Prognostic Assessment of Elderly Patients with Symptoms of Heart Failure by Combining High-Sensitivity Troponin T and N-Terminal Pro-B-Type Natriuretic Peptide Measurements
- 2010
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Ingår i: CLINICAL CHEMISTRY. - : American Association for Clinical Chemistry; 1999. - 0009-9147 .- 1530-8561. ; 56:11, s. 1718-1724
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: N-terminal pro-B-type natriuretic peptide (NT-proBNP) is a useful biomarker in heart failure assessment, whereas measurement of cardiac troponin is central in the diagnosis of patients with acute coronary syndromes. This report examined the prognostic use of combining high-sensitivity cardiac troponin T (hs-cTnT) and NT-proBNP measurements in elderly patients presenting to a primary care center with symptoms associated with heart failure. METHODS: A total of 470 elderly patients (age range 65-86 years) presenting with symptoms of heart failure were recruited from primary healthcare. In addition to clinical examination and echocardiography, hs-cTnT and NT-proBNP plasma concentrations were measured. All patients were followed for 10 years, and cardiovascular mortality was registered. RESULTS: By use of the hs-cTnT assay, 80.4% of the population had plasma concentrations above the lower detection limit of the assay. Of those displaying a plasma concentration of hs-cTnT andgt;99th percentile of a healthy population, 43% also had an NT-proBNP concentration in the fourth quartile (andgt;507 ng/L). In the multivariate analysis, we observed a 2.5-fold increased risk for cardiovascular mortality in individuals with a plasma NT-proBNP concentration andgt;507 ng/L (P andlt; 0.0001). Conversely, patients with hs-cTnT andgt;99th percentile displayed an approximately 2-fold increased risk for cardiovascular mortality (P = 0.0002). Combining the 2 biomarkers, NT-proBNP concentrations andgt;507 ng/L with hs-cTnT andgt;99th percentile increased the risk 3-fold, even after adjustment for clinical variables such as age, sex, impaired estimated glomerular filtration rate, and anemia (P andlt; 0.0001). CONCLUSIONS: hs-cTnT and NT-proBNP measurements combined provide better prognostic information than using either biomarker separately in elderly patients with symptoms associated with heart failure.
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| 2. |
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| 3. |
- Jiang, Jieying, et al.
(författare)
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Association of SRD5A2 variants and serum androstane-3alpha,17beta-diol glucuronide concentration in Chinese elderly men.
- 2010
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Ingår i: Clinical chemistry. - : Oxford University Press (OUP). - 1530-8561 .- 0009-9147. ; 56:11, s. 1742-9
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Tidskriftsartikel (refereegranskat)abstract
- Results of recent studies have demonstrated that genetic variants of the enzyme steroid 5α reductase type II (SRD5A2) are associated with serum concentrations of major androgen metabolites such as conjugates of androstane-3α,17β-diol-glucuronide (3α-diol-G). However, this association was not consistently found among different ethnic groups. Thus, we aimed to determine whether the association with SRD5A2 genetic variations exists in a cohort of healthy Chinese elderly men, by examining 2 metabolite conjugates: androstane-3α,l7β-diol-3-glucuronide (3α-diol-3G) and androstane-3α,17β-diol-17-glucuronide (3α-diol-17G).
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| 4. |
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| 5. |
- Ristiniemi, Noora, et al.
(författare)
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Dry-Reagent Double-Monoclonal Assay for Cystatin C
- 2010
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Ingår i: Clinical Chemistry. - : Oxford University Press (OUP). - 0009-9147 .- 1530-8561. ; 56:9, s. 1424-1431
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Cystatin C is a low molecular weight cysteine proteinase inhibitor whose plasma or serum concentrations have been shown to be better correlated with glomerular filtration rate than serum creatinine concentrations. Routine assays for cystatin C are based on use of polyclonal antibodies and immunoturbidimetric and nephelometric designs. This study aimed to develop a double-monoclonal immunoassay for cystatin C. METHODS: We tested functionality of 42 2-site antibody combinations involving 7 monoclonal antibodies with recombinant and plasma cystatin C. We developed a heterogeneous assay using 2 antibodies selected to give the best analytical performance. The assay used a dilution step and was based on a dry-reagent, all-in-one immunoassay concept with time-resolved fluorometry. The assay was performed on an automated immunoanalyzer in single wells that contained all the required assay components. We used heparin-derived plasma samples for methodological evaluation of the assay. RESULTS: From a relative epitope map involving 7 cystatin C-specific antibodies, we selected a pair of antibodies for a 2-site sandwich-type dry-reagent assay. Total assay time was 15 min, and 10 mu L of a 100-fold diluted sample was used. The analytical detection limit (background + 3SD) and functional detection limit (CV 20%) were 0.01 mg/L and 0.02 mg/L, respectively. Within-run and total assay imprecision were < 4.7% and < 5.6% (at 0.84-3.2 mg/L), respectively, and plasma recoveries of added cystatinCwere 94%-110%. Regression analysis with the Roche particle-enhanced immunoturbidimetric method yielded the following (SD): slope, 1.391 (0.029); y-intercept, - 0.152 (0.045) mg/L; S-y vertical bar x = 0.294 mg/L (n = 31). CONCLUSIONS: The developed assay enables rapid and reliable measurement of cystatin C. (C) 2010 American Association for Clinical Chemistry
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| 6. |
- Zegers, Ingrid, et al.
(författare)
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Characterization of the New Serum Protein Reference Material ERM-DA470k/IFCC: Value Assignment by Immunoassay
- 2010
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Ingår i: Clinical Chemistry. - : Oxford University Press (OUP). - 0009-9147 .- 1530-8561. ; 56:12, s. 1880-1888
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The availability of a suitable matrix reference material is essential for standardization of the immunoassays used to measure serum proteins. The earlier serum protein reference material ERM-DA470 (previously called CRM470), certified in 1993, has led to a high degree of harmonization of the measurement results. A new serum protein material has now been prepared and its suitability in term of homogeneity and stability has been verified; after characterization, the material has been certified as ERM-DA470k/IFCC. METHODS: We characterized the candidate reference material for 14 proteins by applying a protocol that is considered to be a reference measurement procedure, by use of optimized immunoassays. ERM-DA470 was used as a calibrant. RESULTS: For 12 proteins [alpha(2) macroglobulin (A2M), alpha(1) acid glycoprotein (orosomucoid, AAG), alpha(1) antitrypsin (alpha(1)-protease inhibitor, AAT), albumin (ALB), complement 3c (C3c), complement 4 (C4), haptoglobin (HPT), IgA, IgG, IgM, transferrin (TRF), and transthyretin (TTR)], the results allowed assignment of certified values in ERM-DA470k/IFCC. For CRP, we observed a bias between the lyophilized and liquid frozen materials, and for CER, the distribution of values was too broad. Therefore, these 2 proteins were not certified in the ERM-DA470k/IFCC. Different value transfer procedures were tested (open and closed procedures) and found to provide equivalent results. CONCLUSIONS: A new serum protein reference material has been produced, and values have been successfully assigned for 12 proteins. (C) 2010 American Association for Clinical Chemistry
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| 7. |
- Zieba, Agata, et al.
(författare)
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Bright-Field Microscopy Visualization of Proteins and Protein Complexes by In Situ Proximity Ligation with Peroxidase Detection
- 2010
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Ingår i: Clinical Chemistry. - : Oxford University Press (OUP). - 0009-9147 .- 1530-8561. ; 56:1, s. 99-110
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The in situ proximity ligation assay (PLA) allows a protein or protein complex to be represented as an amplifiable DNA molecule. Recognition is mediated by proximity probes consisting of antibodies coupled with oligonucleotides. Upon dual binding of the proximity probes, the oligonucleotides direct the formation of a circular DNA molecule, which is then amplified by rolling-circle replication. The localized concatemeric product is then detected with fluorescent probes. The in situ PLA enables localized detection of individual native proteins or interacting protein pairs in fixed cells or tissue sections, thus providing an important tool for basic and clinical research. METHODS: We used horseradish peroxidase (HRP)conjugated oligonucleotides to couple in situ PLA with enzymatic visualization of the localized detection event. RESULTS: We demonstrate the detection of protein complexes, both in cells and in tissue sections, and show that we can quantify the complexes with image-analysis software specially developed for recognizing HRP signals in bright-field microscopy images. We show that fluorescence and HRP signals produce equivalent results, both ill cultured cells and in tissue samples. CONCLUSIONS: The combination of in situ PLA with bright-field detection and automated image analysis allows the signals present to be Counted in an automated fashion and thus provides a sensitive and specific method for quantification of proteins and protein complexes with bright-field microscopy. With this approach, in situ PLA can be used without the requirement for expensive fluorescence microscopes, thereby avoiding problems with nonspecific fluorescence while maintaining compatibility with conventional histologic staining.
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