| 1. |
- Edlund, Bror, et al.
(författare)
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A proposed stoichiometrical calibration procedure to achieve transferability of D-dimer measurements and to characterize the performance of different methods
- 2006
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Ingår i: Clinical Biochemistry. - : Elsevier BV. - 0009-9120 .- 1873-2933. ; 39:2, s. 137-142
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: There is little transferability between D-dimer levels obtained by different reagents today. This makes it difficult to compare results from different clinical studies. OBJECTIVES: We give a comprehensive proposal for calibration of D-dimer assays. All crucial steps and underlying assumptions are made explicit. METHODS: The new approach is based on using a set of fibrinolysates of patient samples clotted and treated with tPA to obtain maximal conversion to D-dimers. Their expected maximal D-dimer concentrations are calculated stoichiometrically from their different fibrinogen values and the published molecular masses of fibrinogen and average D-dimer. The characteristics of five latex enhanced D-dimer immunoassays were also tested against early and late fibrin fragments using this procedure. These were produced by prolonged fibrinolysis of a set of patient samples of varying fibrinogen concentrations. RESULTS: These varied typically between methods and lysis times. One of the methods showing the highest yield irrespective of lysis time was used for calibration. A linear standard curve with zero intercept and R2 = 0.95 was obtained. CONCLUSION: Following this procedure will allow better transferability of D-dimer in future clinical trails.
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| 2. |
- Filler, G, et al.
(författare)
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Cystatin C as a marker of GFR - history, indications, and future research
- 2005
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Ingår i: Clinical Biochemistry. - : Elsevier BV. - 1873-2933 .- 0009-9120. ; 38:1, s. 1-8
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Forskningsöversikt (refereegranskat)abstract
- Objective: To summarize recent knowledge on the small molecular weight protein cystatin C (cys-C) and its use as a marker of the glomerular filtration rate (GFR). Methods: A multinational expert meeting was held in April 2002 in Marburg, Germany. Contributors summarized their main findings. Conclusions: Cys-C is at least equal if not superior to serum creatinine as a marker of GFR. The independence from height, gender, age. and muscle mass is advantageous. Select patient groups such as children, the elderly, and patients with reduced muscle mass benefit in particular.
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| 3. |
- Flodin, Mats, et al.
(författare)
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Performance evaluation of a particle-enhanced turbidimetric cystatin C assay on the Abbott ci8200 analyzer
- 2009
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Ingår i: Clinical Biochemistry. - : Elsevier BV. - 0009-9120 .- 1873-2933. ; 42:9, s. 873-876
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: Glomerular filtration rate (GFR) is widely accepted as the best overall measure of kidney function. Cystatin C is a novel endogenous GFR marker that has been shown to be superior to creatinine for estimation of GFR in several studies. There is a need for cystatin C assays adapted to routine chemistry instrument to minimize turnaround times and allowing 24 h/day availability. MATERIALS AND METHODS: We have evaluated a new cystatin C assay developed for Architect cSystem (Abbott Laboratories, Abbott Park, IL, USA). RESULTS: The cystatin C assay showed good agreement with the corresponding assay from Dade Behring (Deerfield, IL, USA). The assay has a very low total imprecision and a good linearity. CONCLUSIONS: The new cystatin C assay is an interesting alternative to current cystatin C assays. On an Architect cSystem the assay can be performed with the same turnaround times and availability as creatinine.
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| 4. |
- Hultberg, Malin, et al.
(författare)
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The polyphenol quercetin strongly increases homocysteine production in a human hepatoma (Hep G2) cell line.
- 2006
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Ingår i: Clinical Biochemistry. - : Elsevier BV. - 1873-2933 .- 0009-9120. ; 39:2, s. 160-163
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Tidskriftsartikel (refereegranskat)abstract
- Objective: The metabolism of homocysteine is influenced by several dietary factors, including folate, cobalamin and possibly also the intake of polyhydroxylated phenolic compounds (polyphenols), which were shown to increase plasma homocysteine (tHcy) concentration. In order to reveal the cause of the increased plasma tHcy, we have therefore investigated the effects of a polyphenol in cell cultures from human cell lines. Design and methods: We have studied the influence of the polyphenol quercetin (Quer) on intra- and extracellular homocysteine concentrations in HeLa and hepatoma cell cultures. Results: The main finding is an increased concentration of extracellular homocysteine in the presence of Quer in hepatoma cell cultures, whereas there were no significant changes of homocysteine concentration in HeLa cell cultures. There was no effect on cellular growth, as judged by cell protein. The presence of adenosyl-dialdehyde, an inhibitor of adenosyl-homocysteine hydrolase, abolished the increased extracellular concentration of homocysteine observed in hepatoma cell cultures in the presence of Quer. Conclusion: The antioxidative agent Quer strongly increased the extracellular concentration of homocysteine in hepatoma cell cultures probably due to increased cellular methylation. In the human body, the same phenomenon might lead to increased plasma tHcy. Since elevated plasma tHcy is associated with premature vascular disease, high long-lasting dietary intake of polyphenols might be harmful. The interaction between Quer and homocysteine turnover may therefore warrant a re-evaluation of polyphenols as relatively harmless antioxidative food supplements or therapeutic antioxidative agents. (c) 2005 The Canadian Society of Clinical Chemists. All rights reserved.
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| 5. |
- Isaksson, Helena S., et al.
(författare)
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Preanalytical aspects of quantitative TaqMan real-time RT-PCR : applications for TF and VEGF mRNA quantification
- 2006
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Ingår i: Clinical Biochemistry. - Ottawa : Canadian soc. of clinical chemists. - 0009-9120 .- 1873-2933. ; 39:4, s. 373-377
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: The present paper focuses on preanalytical aspects of tissue factor (TF) and vascular endothelial growth factor (VEGF) mRNA quantification: the choice of blood collection tubes and defining the time frame allowed before processing the sample. DESIGN AND METHODS: Blood was collected from healthy volunteers in K(3) EDTA tubes, CPT, endotoxin-free EndoTube tubes and in PAXgene tubes. Total RNA concentration was determined by absorbance readings at 260 nm with a GeneQuantII UV spectrophotometer. RNA quantity and quality were also determined by the Lab on a Chip technique (Agilent 2100 Bioanalyzer). Real-time RT-PCR assays were performed by the TaqMan technology. RESULTS: The more expensive PAXgene and CPT tubes and the Endo tubes did not give superior results from those obtained in inexpensive routine K(3) EDTA tubes. The PAXgene tubes preserved high molecular mass rRNA better than the other tubes. CONCLUSION: Both the PAXgene system and routine EDTA tubes are suitable for clinical purposes aimed at quantitation of mRNA for TF and VEGF. PAXgene yielded rRNA that was less degraded but had lower mRNA per microg extracted RNA. A time frame up to 24 h until sample processing is acceptable for TF and VEGF mRNA.
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| 6. |
- Jurek, Aleksandra, et al.
(författare)
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The ability of HDL to inhibit VCAM-1 expression and oxidized LDL uptake is impaired in renal patients
- 2008
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Ingår i: Clinical Biochemistry. - : Elsevier BV. - 0009-9120 .- 1873-2933. ; 41:12, s. 1015-1018
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: This study examines the ability of HDL from hemodialysis (HD) and continuous ambulatory peritoneal dialysis (CAPD) patients to suppress the expression of adhesion molecules in endothelial cells (ICAM-1, VCAM-1) and in monocytes (LFA-1, VLA-4) and to inhibit the uptake of oxidized LDL by macrophages. Design and methods: Gene expression and the uptake of oxidized LDL were determined in 12 HD patients, 12 CAPD patients and 14 healthy volunteers. Results: HDL from renal patients were less effective than control lipoproteins in reducing VCAM-1 expression. HDL from CAPD patients inhibited LFA-1 expression to the highest extent. The ability of HDL from renal patients to reduce oxidized LDL uptake was lower compared to control group. Conclusions: Decreased ability of HDL to suppress expression of VCAM-1 in endothelial cells and the uptake of oxidized LDL by macrophages can be one of the risk factors for atherosclerosis development in patients with renal failure.
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| 7. |
- Larsson, Anders, et al.
(författare)
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Low diurnal variability of apolipoprotein A1, apolipoprotein B and apolipoprotein B/apolipoprotein A1 ratio during normal sleep and after an acute shift of sleep
- 2008
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Ingår i: Clinical Biochemistry. - : Elsevier BV. - 0009-9120 .- 1873-2933. ; 41:10-11, s. 859-862
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: The aim of this study was to study the diurnal variation of the cardiovascular risk markers apolipoprotein A1 and B and apo B/apo A1 ratio. DESIGN AND METHODS: We have studied the diurnal variation of apolipoprotein A1, apolipoprotein B and apo B/apo A1 ratio during night sleep and the day sleep conditions in seven healthy volunteers (age 22-32 yr). Samples were collected every hour to evaluate the effect of different sampling times on the test results. RESULTS: The lowest diurnal coefficient of variation (CV) was observed for the apo B/apo A1 ratio, which usually was below 2% but also apolipoprotein A1, apolipoprotein B showed low CV. There were no significant differences between nightsleep and daysleep for any of the studied markers. CONCLUSION: Even if there was a diurnal variation for these markers, the variation was very low. Thus, sampling does not have to be restricted to certain times of the day.
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| 8. |
- Larsson, Anders, et al.
(författare)
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Patient selection has a strong impact on cystatin C and Modification of Diet in Renal Disease (MDRD) estimated glomerular filtration rate
- 2008
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Ingår i: Clinical Biochemistry. - : Elsevier BV. - 0009-9120 .- 1873-2933. ; 41:16-17, s. 1355-1361
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Estimation of the glomerular filtration rate (GFR) is essential for the evaluation of patients with kidney disease, and for correct dosage of drugs that are eliminated from the circulation by the kidneys. In most cases GFR is estimated based on serum creatinine and the Modification of Diet in Renal Disease (MDRD) formula. As both cystatin C and creatinine are used for the determination of GFR it is important to investigate if estimated GFR by the two methods differ in various patient groups. DESIGN AND METHODS: We have compared cystatin C and MDRD estimated GFR calculated from the same request from primary care units (n=488), a cardiology ward (n=826), the cardiointensive care unit (n=1026), two oncology wards (n=919 and 1021), and the neurosurgical intensive care unit (n=1515) in an observational cross-sectional study. RESULTS: We found better agreement between the two GFR estimates in samples from primary care patients and patients in the cardiology wards, than in samples from oncology wards or the neurosurgical intensive care unit. In the latter settings there was a pronounced difference between the two GFR estimates. CONCLUSION: The comparisons show that differences in patient selections have a strong impact on the agreement between cystatin C and MDRD estimated glomerular filtration rate.
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| 9. |
- Olson, Fredrik J., 1975, et al.
(författare)
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Soluble urokinase-type plasminogen activator receptor forms in plasma as markers of atherosclerotic plaque vulnerability.
- 2009
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Ingår i: Clinical biochemistry. - : Elsevier BV. - 1873-2933 .- 0009-9120.
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES:: To test if circulating forms of the soluble urokinase-type plasminogen activator receptor (suPAR) are potential biomarkers of plaque vulnerability. DESIGN AND METHODS:: Plasma concentrations of suPAR(I-III), suPAR(II-III) and uPAR(I) were measured by time-resolved fluorescence immunoassays in Caucasian patients operated for symptomatic carotid atherosclerosis (n=255). Local suPAR release from plaques into the circulation was assessed in plasma passing retrogradely over the plaque in the carotid artery, collected during surgery (n=7). RESULTS:: The suPAR(I-III) (P=0.03) and suPAR(II-III) (P=0.006) concentrations were higher after ischemic strokes and transient ischemic attacks, i.e., clinical subgroups associated with poorer prognosis and a less stable plaque phenotype, than after amaurosis fugax. Slightly elevated suPAR(I-III) levels were found in plasma from the carotid lesion. However, refuting the hypothesis, the concentrations of the suPAR forms were not higher in patients with short intervals between clinical event and blood sampling compared with those with long intervals. Age, inflammatory markers and diabetes were confounding factors independently associated with suPAR forms. CONCLUSION:: Circulating suPAR forms are probably not useful biomarkers of atherosclerotic plaque vulnerability.
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| 10. |
- Rissanen, Maria, et al.
(författare)
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Novel homogenous time-resolved fluorometric RT-PCR assays for quantification of PSA and hK2 mRNAs in blood
- 2007
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Ingår i: Clinical Biochemistry. - : Elsevier BV. - 1873-2933 .- 0009-9120. ; 40:1-2, s. 111-118
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: The purpose of this study was to design, validate, and optimize internally standardized real-time quantitative RT-PCR assays and to identify and avoid problems with assay reliability and examine the impact of an exogenous internal standard. Design and methods: The model system consisted of internally standardized quantitative real-time RT-PCR assays specific for PSA and hK2 mRNA based on time-resolved fluorometric detection of lanthanide chelates. Results: Reproducibility was best when large copy numbers (> 5000 per milliliter blood) were analyzed. Addition of an exogenous target-mimicking internal standard had no significant effect on the reproducibility of the method, but increased the calculated copy numbers by an average of 2-fold. Conclusions: We developed an internally standardized, specific and reproducible real-time RT-PCR analysis method for PSA and hK2 mRNA in circulating cells in the bloodstream. Both PSA and hK2 assays are sufficiently sensitive to detect two LNCaP cells per milliliter whole blood. (c) 2006 The Canadian Society of Clinical Chemists. All rights reserved.
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