| 1. |
- Ahlqvist, Emma, et al.
(author)
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Genetics of type 2 diabetes
- 2011
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In: Clinical Chemistry. - : Oxford University Press (OUP). - 0009-9147 .- 1530-8561. ; 57:2, s. 241-254
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Research review (peer-reviewed)abstract
- Background: Type 2 diabetes (T2D) is a complex disorder that is affected by multiple genetic and environmental factors. Extensive efforts have been made to identify the disease-affecting genes to better understand the disease pathogenesis, find new targets for clinical therapy, and allow prediction of disease.Content: Our knowledge about the genes involved in disease pathogenesis has increased substantially in recent years, thanks to genomewide association studies and international collaborations joining efforts to collect the huge numbers of individuals needed to study complex diseases on a population level. We have summarized what we have learned so far about the genes that affect T2D risk and their functions. Although more than 40 loci associated with T2D or glycemic traits have been reported and reproduced, only a minor part of the genetic component of the disease has been explained, and the causative variants and affected genes are unknown for many of the loci.Summary: Great advances have recently occurred in our understanding of the genetics of T2D, but much remains to be learned about the disease etiology. The genetics of T2D has so far been driven by technology, and we now hope that next-generation sequencing will provide important information on rare variants with stronger effects. Even when variants are known, however, great effort will be required to discover how they affect disease risk.
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| 2. |
- Alehagen, Urban, et al.
(author)
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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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In: CLINICAL CHEMISTRY. - : American Association for Clinical Chemistry; 1999. - 0009-9147 .- 1530-8561. ; 56:11, s. 1718-1724
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Journal article (peer-reviewed)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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| 3. |
- Bredberg, Anna, et al.
(author)
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Exhaled Endogenous Particles Contain Lung Proteins.
- 2012
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In: Clinical Chemistry. - : Oxford University Press (OUP). - 1530-8561 .- 0009-9147. ; 58:2, s. 431-440
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Journal article (peer-reviewed)abstract
- BACKGROUND:We recently developed a novel, noninvasive method for sampling nonvolatile material from the distal airways. The method is based on the collection of endogenous particles in exhaled air (PEx). The aim of this study was to characterize the protein composition of PEx and to verify that the origin of PEx is respiratory tract lining fluid (RTLF).METHOD:Healthy individuals exhaled into the sampling device, which collected PEx onto a silicon plate inside a 3-stage impactor. After their extraction from the plates, PEx proteins were separated by SDS-PAGE and then analyzed by LC-MS. Proteins were identified by searching the International Protein Index human database with the Mascot search engine.RESULTS:Analysis of the pooled samples identified 124 proteins. A comparison of the identified PEx proteins with published bronchoalveolar lavage (BAL) proteomic data showed a high degree of overlap, with 103 (83%) of the PEx proteins having previously been detected in BAL. The relative abundances of the proteins were estimated according to the Mascot exponentially modified protein abundance index protocol and were in agreement with the expected protein composition of RTLF. No amylase was detected, indicating the absence of saliva protein contamination with our sampling technique.CONCLUSIONS:Our data strongly support that PEx originate from RTLF and reflect the composition of undiluted RTLF.
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| 4. |
- 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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| 5. |
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| 6. |
- 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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| 7. |
- Eggers, Kai M, et al.
(author)
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Change in Growth Differentiation Factor 15 Concentrations Over Time Independently Predicts Mortality in Community-Dwelling Elderly Individuals
- 2013
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In: Clinical Chemistry. - : Oxford University Press (OUP). - 0009-9147 .- 1530-8561. ; 59:7, s. 1091-1098
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Journal article (peer-reviewed)abstract
- BACKGROUND:Growth differentiation factor 15 (GDF-15) is emerging as a powerful risk indicator in both cardiovascular disease patients and community-dwelling individuals. We investigated GDF-15 concentrations and their changes over 5 years in elderly individuals from the community, together with the underlying conditions and prognostic implications of these measurements.METHODS:We analyzed GDF-15 concentrations using a sandwich immunoassay in participants from the PIVUS (Prospective Investigation of the Vasculature in Uppsala Seniors) study. Measurements were performed at both 70 (n = 1004) and 75 (n = 813) years of age. Median follow-up was 8.0 years.RESULTS:Over time, GDF-15 concentrations increased by 11.0% (P < 0.001). These changes were related to male sex, hypertension, diabetes, heart failure, renal function, and concentrations of N-terminal pro–B-type natriuretic peptide (NT-proBNP). Significant relationships also emerged between changes in GDF-15 and NT-proBNP, C-reactive protein, and renal function between ages 70 and 75. The R2 value of this model was 0.20. GDF-15 concentrations independently predicted all-cause mortality [hazard ratio 4.0 (95% CI 2.7–6.0)] with results obtained at ages 70 and 75 as updated covariates. Baseline GDF-15 concentrations improved prognostic discrimination and reclassification [c-statistic 0.06 (P = 0.006); integrated discrimination improvement = 0.030 (P = 0.004); category-free net reclassification improvement = 0.281 (P = 0.006)]. Change in GDF-15 concentrations over time independently predicted even all-cause mortality occurring after age 75 [hazard ratio 3.6 (95% CI 2.2–6.0)].CONCLUSIONS:GDF-15 concentrations and their changes over time are powerful predictors of mortality in elderly community-dwelling individuals. GDF-15 concentrations increase with aging, and these changes are explained only partially by cardiovascular risk factors, indicators of neurohumoral activation and inflammation, and renal function. Thus GDF-15 reflects both cardiovascular and other biological processes closely related to longevity.
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| 8. |
- Eggers, Kai M, et al.
(author)
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Factors Influencing the 99th Percentile of Cardiac Troponin I Evaluated in Community-Dwelling Individuals at 70 and 75 Years of Age
- 2013
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In: Clinical Chemistry. - : Oxford University Press (OUP). - 0009-9147 .- 1530-8561. ; 59:7, s. 1068-1073
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Journal article (peer-reviewed)abstract
- BACKGROUND: We aimed to investigate the effects of sex, prevalent cardiovascular disease (CVD), and ageing on the 99th percentile of cardiac troponin I (cTnI).METHODS:cTnI was measured using a high-sensitivity assay (Abbott Diagnostics) in 814 community-dwelling individuals at both 70 and 75 years of age. We determined the cTnI 99th percentiles separately using nonparametric methods in the total sample, in men and women, and in individuals with and without CVD.RESULTS:The cTnI 99th percentile at baseline was 55.2 ng/L for the total cohort. Higher 99th percentiles were noted in men (69.3 ng/L) and individuals with CVD (74.5 ng/L). The cTnI 99th percentile in individuals free from CVD at baseline (n = 498) increased by 51% from 38.4 to 58.0 ng/L during the 5-year observation period. Relative increases ranging from 44% to 83% were noted across all subgroups. Male sex [odds ratio, 5.3 (95% CI, 1.5-18.3)], log-transformed N-terminal pro-B-type natriuretic peptide [odds ratio, 1.9 (95% CI, 1.2-3.0)], and left-ventricular mass index [odds ratio, 1.3 (95% CI, 1.1-1.5)] predicted increases in cTnI concentrations from below the 99th percentile (i.e., 38.4 ng/L) at baseline to concentrations above the 99th percentile at the age of 75 years.CONCLUSIONS: cTnI concentration and its 99th percentile threshold depend strongly on the characteristics of the population being assessed. Among elderly community dwellers, higher concentrations were seen in men and individuals with prevalent CVD. Ageing contributes to increasing concentrations, given the pronounced changes seen with increasing age across all subgroups. These findings should be taken into consideration when applying cTnI decision thresholds in clinical settings.
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| 9. |
- 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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| 10. |
- Hammarsten, Ola, et al.
(author)
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Troponin T percentiles from a random population sample, emergency room patients and patients with myocardial infarction
- 2012
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In: Clinical Chemistry. - : Oxford University Press (OUP). - 1530-8561 .- 0009-9147. ; 58:3, s. 628-637
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Journal article (peer-reviewed)abstract
- BACKGROUND: High-sensitivity cardiac troponin T (cTnT) assays detect small clinically important myocardial infarctions (MI) but also yield higher rates of false-positive results owing to increased concentrations sometimes present in patients without MI. Better understanding is needed of factors influencing the 99th percentile of cTnT concentrations across populations and the frequency of changes in cTnT concentrations >20% often used in combination with increased cTnT concentrations for diagnosis of MI. METHODS: cTnT percentiles were determined by use of the Elecsys® hscTnT immunoassay (Modular® Analytics E170) in a random population sample, in emergency room (ER) patients, and in patients with non–ST-elevation MI (NSTEMI). Changes in cTnT concentrations were determined in hospitalized patients without MI. RESULTS: The 99th cTnT percentile in a random population sample (median age, 65 years) was 24 ng/L. In ER patients <65 years old without obvious conditions that increase cTnT, the 99th cTnT percentile was 12 ng/L with little age dependence, whereas in those >65 years old it was 82 ng/L and highly age dependent. In hospitalized patients without MI the 97.5th percentile for change in the cTnT concentration was 51%–67%. cTnT remained below the 99th percentile (12 ng/L) in 1% of patients with NSTEMI until 8.5 h after symptom onset and 6 h after ER arrival. CONCLUSIONS: Age >65 years was the dominant factor associated with increased cTnT in ER patients. This age association was more prominent in ER patients than in a random population sample. Changes in serial cTnT concentrations >20% were common in hospitalized patients without MI.
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