| 1. |
- Strandberg, Karin, et al.
(författare)
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Evaluation of a rapid automated assay for analysis of von Willebrand ristocetin cofactor activity.
- 2006
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Ingår i: Clinical and Applied Thrombosis/Hemostasis. - : SAGE Publications. - 1938-2723 .- 1076-0296. ; 12:1, s. 61-67
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Tidskriftsartikel (refereegranskat)abstract
- A commercially available turbidometric assay has been evaluated for the measurement of von Willebrand factor ristocetin cofactor activity (VWF:RCo). The assay is simple, rapid, and can be cost-effectively performed on automated coagulation analyzers. This study’s aim is to illustrate the performance of the automated VWF:RCo assay and its capacity to identify patients with von Willebrand disease (VWD). By direct comparison with a conventional VWF:RCo assay, performed on an aggregometer, the concordance between the two assays was 96%. With minor modifications, the automated assay showed a detection level of 0.03 kIU/L with linearity to 2.00 kIU/L. The imprecision of the automated assay was reduced compared to the conventional assay procedure with CV of 6.8% at the 1.00 kIU/L level and 8.6% at the 0.30 kIU/L level. The automated VWF:RCo assay was also suitable as a screening test to detect VWD in patients investigated for the cause of an increased bleeding tendency. In this situation the automated VWF:RCo assay was tested simultaneously with an automated immunoassay for von Willebrand antigen. Receiver operating curves for the diagnosis of VWD showed a greater area under the curve for the automated VWF:RCo assay compared to the immunoassay, 0.98 vs. 0.94, although the difference did not reach significance. In conclusion, the modified automated VWF:RCo assay shows better precision, lower detection limit, is faster to perform with a lower cost per test compared to the conventional aggregometer based VWF:RCo activity method and is an alternative to an antigen immunoassay as a screening test for VWD.
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| 2. |
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| 3. |
- Persson, Kristina, et al.
(författare)
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Använd hela "analyspaketet" vid utredning av trombospatienten! Och glöm inte släktingarna ...
- 2000
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Ingår i: Läkartidningen. - 0023-7205. ; 97:47, s. 5452-5456
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Tidskriftsartikel (refereegranskat)abstract
- During the last few years several genetic markers have been discovered that contribute to an increased risk of venous thrombosis. Patients who have several genetic markers are at a considerably higher risk of being affected than patients with only one marker. Recommendations are made as to which patients should be investigated, with appropriate laboratory analyses, when an increased risk of venous thrombosis is suspected. Most of the analyses can be done even if the patient is undergoing warfarin treatment.
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| 4. |
- Przybyla, Beata, et al.
(författare)
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Coordinated responses of natural anticoagulants to allogeneic stem cell transplantation and acute GVHD – A longitudinal study
- 2017
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 12:12
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Tidskriftsartikel (refereegranskat)abstract
- Background Allogeneic stem cell transplantation (SCT) enhances coagulation via endothelial perturbation and inflammation. Role of natural anticoagulants in interactions between coagulation and inflammation as well as in acute graft-versus-host disease (GVHD) are not well known. The purpose of this study was to define changes in natural anticoagulants over time in association with GVHD. Patients and methods This prospective study included 30 patients who received grafts from siblings (n = 19) or unrelated donors (n = 11). Eight patients developed GVHD. Standard clinical assays were applied to measure natural anticoagulants, represented by protein C (PC), antithrombin (AT), protein S (PS), complex of activated PC with its inhibitor (APC-PCI) and by markers of endothelial activation: Factor VIII coagulant activity (FVIII:C) and soluble thrombomodulin (s-TM) at 6–8 time points over three months. Results Overall, PC, AT and FVIII:C increased in parallel after engraftment. Significant correlations between PC and FVIII:C (r = 0.64–0.82, p<0.001) and between PC and AT (r = 0.62–0.81, p<0.05) were observed at each time point. Patients with GVHD had 21% lower PC during conditioning therapy and 55% lower APC-PCI early after transplantation, as well as 37% higher values of s-TM after engraftment. The GVHD group had also increases of PC (24%), FVIII: C (28%) and AT (16%) three months after transplantation. Conclusion The coordinated activation of natural anticoagulants in our longitudinal study indicates the sustained ability of adaptation to endothelial and inflammatory activation during allogenic SCT treatment. The suboptimal control of coagulation by natural anticoagulants at early stage of SCT may contribute to onset of GVHD.
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| 5. |
- Hillarp, Andreas, et al.
(författare)
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Unveiling the complex effects of direct oral anticoagulants on dilute Russell's viper venom time assays
- 2020
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Ingår i: Journal of Thrombosis and Haemostasis. - : Elsevier BV. - 1538-7933 .- 1538-7836. ; 18:8, s. 1866-1873
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: Dilute Russell viper venom time (dRVVT) assays can be affected by direct oral anticoagulants (DOACs), which may cause false-positive results. However, there are conflicting results indicating significant differences between different reagents and DOACs. Objectives: To evaluate the effect of DOACs on dRVVT assays. Material and Methods: Samples were prepared by adding DOAC (dabigatran, rivaroxaban, apixaban, or edoxaban) to pooled normal plasma in the concentration range 0 to 800 µg/L. Six integrated dRVVT reagents were used, all composed of a screen assay (low phospholipid content) and a confirm assay (high phospholipid content). The screen/confirm dRVVT results were expressed as normalized ratios. To further evaluate the observed differences between tests and DOACs, addition of synthetic phospholipids was used. Results: The dRVVT ratios increased dose dependently for all DOACs, with four of the six tests and the DOAC rivaroxaban having the greatest effect. With one test, the ratios were almost unaffected with increasing DOAC concentration, whereas another test revealed a negative dose dependency for all DOACs. Variable DOAC effects can be explained by different effects on dRVVT screen and confirm clotting time. Adding synthetic phospholipids to samples containing rivaroxaban resulted in greatly reduced screen clotting times and thereby lower calculated dRVVT ratios. Conclusions: There is a great variability in the dRVVT test result with different DOACs. The dRVVT ratios are unaffected for some reagents and this can be explained by an equal dose-dependent effect on both screen and confirm assays. The phospholipid type and content of the different reagents may contribute to the observed differences.
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| 6. |
- Sonesson, Annika, et al.
(författare)
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Determination of serum amyloid P component in seminal plasma and correlations with serum hormone levels in young, healthy men.
- 2011
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Ingår i: Scandinavian Journal of Clinical and Laboratory Investigation. - : Informa UK Limited. - 1502-7686 .- 0036-5513. ; 71:7, s. 569-575
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Tidskriftsartikel (refereegranskat)abstract
- Abstract Serum amyloid P component (SAP) belongs to the pentraxin family of proteins. SAP is evolutionary conserved, and involved in amyloidosis, innate immunity, inflammation, and apoptosis. We have previously described SAP in the male reproductive tract, where it occurs in seminal fluid, on spermatozoa, and in epididymal, seminal vesicle, and prostate tissue. In the present investigation, our aim was to characterize SAP in male reproduction. In short, we developed and evaluated an immunoassay, analysed the concentration of SAP in seminal plasma and serum in samples from healthy men (N = 203), and studied hormonal regulation. SAP in seminal plasma showed a positively skewed distribution and a median concentration of 1.01 mg/L (inter quartile range [IQR] 0.56-1.65 mg/L). SAP in serum had a Gaussian distribution and a median concentration of 40.5 mg/L (IQR 34.2-49.2 mg/L). Furthermore, SAP concentrations in seminal plasma were not correlated with serum concentrations of SAP, testosterone, sex hormone-binding globulin (SHBG), the testosterone/SHBG ratio, inhibin B, or estradiol. Only a weak negative correlation was found between seminal plasma SAP and serum levels of follicle-stimulating hormone (FSH) (Spearman's rho -0.159; p = 0.023) and luteinizing hormone (LH) (Spearman's rho -0.162; p = 0.021). In conclusion, all men investigated had measurable SAP levels in seminal plasma and in serum. SAP concentrations were 40 times lower in seminal fluid than in serum, and there was no correlation between those two variables. It seems that hormonal regulation is not the major pathway regulating seminal plasma SAP, and seminal plasma SAP and serum SAP are not co-regulated.
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| 7. |
- Ornemark, Ulf, et al.
(författare)
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Calibration services in the frame of accredited coagulation EQA schemes - Meeting the IVD directive
- 2006
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Ingår i: Accreditation and Quality Assurance. - : Springer Science and Business Media LLC. - 0949-1775 .- 1432-0517. ; 11:8-9, s. 451-454
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Tidskriftsartikel (refereegranskat)abstract
- Organisers of external quality assurance programmes may, for various reasons, also manufacture in vitro diagnostic medical devices, or provide calibration services. This paper describes measures taken by a Swedish organiser to meet the requirements of the European Commission's directive 98/79/EC for a national calibration of prothrombin time. Quality management system requirements and interactions with coagulation experts are summarised.
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| 8. |
- Armstrong, Elina, et al.
(författare)
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Assay discrepancy in mild haemophilia A
- 2014
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Ingår i: European Journal of Haematology. Supplementum. - : Wiley. - 0902-4506 .- 0902-4441. ; 93:s76, s. 48-50
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Forskningsöversikt (refereegranskat)abstract
- UNLABELLED: There are three main methods used to assay factor VIII (FVIII) activity: the one-stage and two-stage clotting assays and the two-stage chromogenic method. The most commonly used assay for the diagnosis of haemophilia A is the automated one-stage FVIII assay. The classical two-stage FVIII assays are less frequently used. The chromogenic FVIII:C assay is a variant of the two-stage assay. It is easier to use and therefore used more commonly. Recently significant assay discrepancy has been recognised in the FVIII:C measurements in approximately one-third of mild haemophilia A patients. This so-called discrepant mild haemophilia A is characterised by a high ratio of one-stage/two-stage assay with one-stage FVIII levels that are typically more than double those of the two-stage coagulation assay. There are several mutations that destabilise the FVIIIa structure that can explain this result of a more pronounced decrease of the chromogenic FVIII:C activity compared with the one-stage activity. These mutations are clustered at the interfaces of the A1, A2 and A3 domains of the FVIII protein. The inverse discrepancy, where the one-stage assay gives lower FVIII:C results than the chromogenic assay, seems to be associated with mutations found close to important sites for thrombin cleavage or FIX binding. We are carrying out a study of mild haemophilia A samples from the Malmö Haemophilia Centre of families with a unique F8 genotype. The activity of FVIII will be measured using a chromogenic assay and two different one-stage assays. We hope to estimate the true size of assay discrepancy.AIM: This project will review assay discrepancy in mild/moderate haemophilia A and the risk of misdiagnosis. The overall aim is to estimate the size of the problem and to learn from the literature and experiences from our centre as well as to suggest recommendations on how to avoid misdiagnosis.
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| 9. |
- Lindahl, Tomas, et al.
(författare)
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Effects of the oral, direct thrombin inhibitor dabigatran on five common coagulation assays
- 2011
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Ingår i: Thrombosis and Haemostasis. - : F K Schattauer Verlagsgesellschaft MBH. - 0340-6245 .- 2567-689X. ; 105:2, s. 371-378
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Tidskriftsartikel (refereegranskat)abstract
- Dabigatran is an oral, reversible thrombin inhibitor that has shown promising results in large clinical trials. Laboratory monitoring is not needed but the effects on common coagulation assays are incompletely known. Dabigatran was added to plasma from healthy subjects in the concentration range 0-1,000 μg/l and analysed using several reagents for activated thromboplastin time (APTT), prothrombin time (PT), fibrinogen, antithrombin, and activated protein C resistance. Typical trough concentrations are about 50 μg/l, peak concentrations 100-300 μg/l. At 100 μg/l all APTT-results were prolonged. The concentration required to double APTT ranged between 227 and 286 μg/l, the responses for all five reagents were similar. PT-reagents were much less affected with almost no samples above INR 1.2 at 100 μg/l. The effect was sample dilution dependent with PT Quick type more sensitive than PT Owren type methods. If a patient on dabigatran has prolonged APTT, >90 seconds, and Quick PT INR>2 or Owren PT INR>1.5 over-dosing or accumulation of dabigatran should be considered. Two of four fibrinogen reagents underestimated the fibrinogen concentration considerably at expected peak concentration. Methods based on inhibition of thrombin over-estimated the antithrombin concentration, but not Xa-based. The APC-resistance methods over-estimated the APC-ratio, which may lead to miss-classification of factor V Leiden patients as being normal. Different coagulation assays, and even different reagents within an assay group, display variable effects at therapeutic concentrations of dabigatran. Some of these assay variations are of clinical importance, thus knowledge is needed for a correct interpretation of results.
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| 10. |
- Lindberg, Charlotte, et al.
(författare)
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Influence of factor V Leiden on the development of neovascularisation secondary to central retinal vein occlusion.
- 2003
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Ingår i: British Journal of Ophthalmology. - : BMJ. - 1468-2079 .- 0007-1161. ; 87:3, s. 305-306
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Tidskriftsartikel (refereegranskat)abstract
- Aims: To investigate if the presence of factor V Leiden has an influence on the prognosis in central retinal vein occlusion (CRVO). Methods: 166 patients with CRVO were studied retrospectively. They were tested for factor V Leiden using DNA analysis. The presence of the mutation was studied in correlation with the development of neovascular complications 1 year after the thrombotic event. Results: 56 of 166 patients (34%) developed neovascular complications after 1 year. In the patients who had the studied mutation 11 of 20 (55%) had developed neovascular complications after 1 year, compared to 45 of 146 patients (31%) in the group without factor V Leiden (p=0.04). Conclusion: The presence of factor V Leiden seems to enhance the risk of developing neovascular complications in CRVO.
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