| 1. |
- Karlsson, Anna, 1985-, et al.
(författare)
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The effect of tinzaparin on biomarkers in FIGO stages III-IV ovarian cancer patients undergoing neoadjuvant chemotherapy – the TABANETOC trial: study protocol for a randomized clinical multicenter trial
- 2024
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Ingår i: Acta Oncologica. - Uppsala : Medical Journals Sweden. - 0284-186X .- 1651-226X. ; 63, s. 581-585
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Tidskriftsartikel (refereegranskat)abstract
- Background: Tinzaparin, a low-molecular weight heparin (LMWH), has shown anti-neoplastic properties in animal models and in in vitro studies of human cancer cell lines. The reduction of CA-125 levels during neoadjuvant chemotherapy (NACT) in patients with epithelial ovarian cancer (EOC) co-varies with the prognosis; the larger the decrease in CA-125, the better the prognosis.Purpose: This study aims to evaluate the potential anti-neoplastic effects of tinzaparin by investigating changes in serum CA-125 levels in advanced EOC patients who receive NACT.Material and methods: This is an open randomized multicenter pilot trial. Forty patients with EOC selected to receive NACT will be randomized 1:1 to receive daily addition of tinzaparin or no tinzaparin. The processing and treatment of the patients will otherwise follow the recommendations in the Swedish National Guidelines for Ovarian Cancer. Before every cycle of chemotherapy, preoperatively, and 3 weeks after the last cycle of chemotherapy, a panel of biomarkers, including CA-125, will be measured.Patients: Inclusion criteria are women aged 18 years or older, World Health Organization performance status 0–1, histologically confirmed high-grade serous, endometrioid or clear cell EOC, International Federation of Gynecology and Obstetrics (FIGO) stages III-IV. In addition, a CA-125 level of ≥ 250 kIE/L at diagnosis. Exclusion criteria are contraindications to LMWH, ongoing or recent treatment with unfractionated heparin, LMWH, warfarin or non-vitamin K antagonist oral anticoagulants.Interpretation: This study will make an important contribution to the knowledge of the anti-neoplastic effects of tinzaparin in EOC patients and may thus guide the planning of a future study on the impact of tinzaparin on survival in EOC.
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| 2. |
- af Geijerstam, Peder, Doktorand, 1983-, et al.
(författare)
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P-selectin and C-reactive protein in relation to home blood pressure and coronary calcification: a SCAPIS substudy
- 2024
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Ingår i: Journal of Hypertension. - : Lippincott Williams & Wilkins. - 0263-6352 .- 1473-5598.
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Tidskriftsartikel (refereegranskat)abstract
- Background: Soluble P-selectin (sP-selectin) and high-sensitivity C-reactive protein (hsCRP) have previously been associated with hypertension, but the relation with out-of-office blood pressure (BP) and coronary artery calcification score is unknown. We aimed to examine the relationship between sP-selectin, hsCRP and home BP, as well as coronary artery calcification score and carotid artery plaques.Methods: In the Swedish CArdioPulmonary bioImage Study (SCAPIS), 5057 randomly selected participants were evaluated with office and home BP using the semi-automatic Omron M10-IT device. For this cross-sectional study, participants with sP-selectin <4 standard deviations above mean and hsCRP <5 mg/l, representing low-grade inflammation, were included. Using generalized linear models, these inflammatory markers were evaluated in relation to BP classifications, as well as coronary artery calcification score and carotid artery plaques.Results: Of participants, 4548 were included in the analyses. The median age was 57.2 (53.4–61.2) years, and 775 (17.0%) reported taking medication for hypertension. Participants in the highest quartile of sP-selectin [odds ratio (OR) 1.67, 95% confidence interval (CI) 1.40–1.98, P < 0.001] and hsCRP [OR 2.25, (95% CI 1.89–2.60), P < 0.001] were more likely to have sustained hypertension. Participants in the highest quartile of hsCRP were also more likely to have masked hypertension, OR (95% CI) 2.31 (1.72–3.10), P < 0.001 and carotid artery plaques, OR (95% CI) 1.21 (1.05–1.38), P = 0.007.Conclusion: Increased sP-selectin and hsCRP were independently associated with sustained hypertension. These findings indicate an association between hypertension and platelet activity, as expressed by sP-selectin.
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| 3. |
- Alehagen, Urban, 1951-, et al.
(författare)
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Elevated D-dimer level is an independent risk factor for cardiovascular death in out-patients with symptoms compatible with heart failure
- 2004
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Ingår i: Thrombosis and Haemostasis. - 0340-6245 .- 2567-689X. ; 92:6, s. 1250-1258
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Tidskriftsartikel (refereegranskat)abstract
- D-dimer, a marker of fibrin turnover, exhibits many interesting properties as a biological marker of thrombosis. Some of the properties of D-dimer might also be used to provide additional information about patients with heart failure. In this study, we evaluate the prognostic information acquired from D-dimer concerning increased risk of cardiovascular mortality in an elderly population with symptoms associated with heart failure. A cardiologist examined 458 elderly patients, out of 548 invited, attending primary care for symptoms of dyspnoea, fatigue and/or peripheral oedema and assessed NYHA functional class and cardiac function. Abnormal systolic function was defined as EF <40% on Doppler echocardiography. Abnormal diastolic function was defined as reduced E/A ratio and/or an abnormal pattern of pulmonary venous flow. Blood samples were drawn, and BNP and D-dimer were analysed. D-dimer was analysed using an automated micro-latex assay. A statistical analysis was performed to identify the prognostic value of increased plasma concentration of D-dimer. Results showed that during a median follow-up period of 5.5 years, 68 (14%) patients died of cardiovascular disease. No gender difference was noted. A plasma concentration of D-dimer >0.25mg/L increased the risk almost 4-fold. In conclusion, D-dimer is an independent risk factor for cardiovascular mortality that may be used to risk-stratify patients with heart failure. © 2004 Schattauer GmbH, Stuttgart.
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| 4. |
- Alfredsson, Joakim, et al.
(författare)
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Individual long-term variation of platelet reactivity in patients with dual antiplatelet therapy after myocardial infarction.
- 2019
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Ingår i: Platelets. - : Informa UK Limited. - 0953-7104 .- 1369-1635. ; 30:5, s. 572-578
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Tidskriftsartikel (refereegranskat)abstract
- There is a large inter-individual variation in response to clopidogrel treatment, and previous studies have indicated higher risk of thrombotic events in those with high residual platelet reactivity (HPR). Less is known about individual variation over time. The aim of this prospective cohort study was to investigate intra-individual variation in platelet reactivity. Platelet aggregation in whole blood was assessed in 77 patients, at 3 days, 8 days and 6 months after admission for acute myocardial infarction and loading dose of clopidogrel. All patients were treated with aspirin and clopidogrel through 6-month follow-up. We found a significant increase in median ADP-stimulated aggregation from third to eighth day (195 vs. 250 AU*min, p-value = 0.001) but not from day 8 to 6 months (250 vs. 223 AU*min, p-value = 0.666). There was no significant change in the overall rate of HPR (15.6% vs 20.8%, p-value 0.503) or low platelet reactivity (LPR) (37.7% vs 33.8%, p-value = 0.609) from day 8 to 6-month follow-up. In contrast, more than one in four changed HPR status, 15.6% from non-HPR to HPR and 10.4% HPR to non-HPR. A shift in LPR status appeared even more frequent, occurring in about one of three patients. In spite of similar median aggregation and rate of HPR during 6-month follow-up, about one in four of the patients changed HPR status and one in three changed LPR status. This may be important information for a concept of risk stratification based on a single aggregation value early after an acute coronary syndromes.
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| 5. |
- Arbring, Kerstin, 1961-
(författare)
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Two worlds, one goal : A Clinician’s Perspective on Laboratory Analyses in Anticoagulant Treatment
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Almost precisely a century ago, in the 1920s and 1930s, cattle bled to death in North America after being fed moldy hay containing sweet clover, the yellow Melilotus officinalis, and the white Melilotus albus. The toxic substance in the hay inhibiting blood coagulation was identified and named dicumarol. Further development resulted in warfarin, an oral anticoagulant that has been used for over 70 years and still is, even though newer direct-acting oral anticoagulants (DOACs) are mainly replacing it. For some patients, warfarin is still the drug of choice. A safe warfarin treatment needs repeated blood sample analysis (PT-INR), and with the new DOACs come new laboratory challenges. The aim of this thesis was to investigate ways laboratory methods can contribute to improving oral anticoagulant treatment. Paper I explores genetic variants of the enzyme targeted by warfarin, VKORC1. The result shows that the haplotype VKORC1*2 is the most important of the VKORC1 haplotypes for warfarin dosage, with a lower dose requirement. The VKORC1*2 haplotype was also related to more unstable PT-INR levels. Paper II describes a cross-section study comparing warfarin treatment control, as PT-INRs within the intended therapeutic range, in primary health care centers (PHCCs) and specialized anticoagulation clinics (ACCs). Both settings showed good therapeutic control, with at least as good therapeutic control in the PHCCs as in the ACCs. Today, almost all warfarin treatment in our region is centralized to ACCs. Paper III focuses on the modification of a point-of-care PT method. A ratio of PT from two different dilutions of each patient sample was calculated and used as an indirect measure of DOAC activity. There were close correlations between the PT ratio and drug concentrations measured at the hospital laboratory. The detection level varies between DOACs and may limit its use in some situations. Paper IV evaluated the MRX PT DOAC, an assay based on the PT ratio principle. It was found to be able to detect potentially interfering DOAC levels in plasma samples. Confirmatory testing is recommended, as is sensitivity improvement for the detection of specific interferences.
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| 6. |
- Arvidsson, Sara, 1977-, et al.
(författare)
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Detection of surface bound complement at increasing serum anticoagulant concentrations.
- 2008
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Ingår i: Colloids and surfaces. B, Biointerfaces. - : Elsevier BV. - 0927-7765 .- 1873-4367. ; 62:2, s. 214-9
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Tidskriftsartikel (refereegranskat)abstract
- Surface mediated immune complement activation can be detected by a variety of antibody utilizing methods such as ELISA, fluorescence- or radiolabelling techniques, QCM, and ellipsometry. In the present work we investigated how the common anticoagulants heparin, dalteparin, fondaparinux and sodium citrate affected the binding of anti-complement factor 3c (anti-C3c) on a model complement activator surface, immobilised IgG, after incubation in human blood serum. The results show, as expected, that different anticoagulants affect the antibody binding differently. Increasing amounts of heparin, dalteparin and sodium citrate in normal serum resulted in a decreasing anti-C3c binding. The antibody deposition was not sensitive for the fondaparinux concentration. Surprisingly high concentrations of anti-coagulantia were needed to completely eradicate the antibody binding. Experiments in EGTA-serum showed that anticoagulants interfered directly with both the classical and alternative pathways. Control C3a-des arg ELISA measurements show that the lowered antibody surface binding was not a result of complement depletion in serum. Kallikrein generation by hydrophilic glass surfaces was not affected by high anticoagulant concentrations.
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| 7. |
- Axelsson Rosén, Stina, et al.
(författare)
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In vitro effects of antipsychotics on human platelet adhesion and aggregation and plasma coagulation
- 2007
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Ingår i: Clinical and experimental pharmacology & physiology. - : Wiley. - 0305-1870 .- 1440-1681. ; 34:8, s. 775-780
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Tidskriftsartikel (refereegranskat)abstract
- 1. Several studies suggest an association between venous thromboembolism and the use of antipsychotic drugs, especially clozapine, but the biological mechanisms are unknown. It has been suggested that antipsychotic drugs enhance aggregation of platelets and thereby increase the risk of venous thrombosis. The purpose of the present study was to examine the effects of clozapine and its main metabolite, N-desmethyl clozapine, as well as olanzapine, risperidone and haloperidol, on platelet adhesion and aggregation and on plasma coagulation in vitro. 2. Blood was collected from healthy subjects free of medication. Platelet adhesion to different protein surfaces and aggregation were measured in microplates. The coagulation methods of activated partial thromboplastin time (APTT) and prothrombin time were performed in platelet-poor plasma. 3. Clozapine was the only compound that increased platelet adhesion and aggregation and shortened APTT. The effect appeared at therapeutic concentrations and was significant but weak. 4. This weak effect of clozapine on haemostasis may explain, in part, the association of this compound and venous thromboembolism. © 2007 The Authors.
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| 8. |
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| 9. |
- Bian, Li, et al.
(författare)
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Rutinmässig screening med APTT är inte indicerad före operation : [Routine screening with APTT is not indicated before surgery
- 2022
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Ingår i: Läkartidningen. - : Sveriges Läkarförbund. - 0023-7205 .- 1652-7518. ; 119
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Forskningsöversikt (refereegranskat)abstract
- Activated partial thromboplastin time (APTT) is widely practiced in preoperative screening. The value of using this test to predict the risk of perioperative bleeding is not well documented in Sweden. In this article, a literature review is performed to determine whether unselected APTT testing can predict abnormal perioperative bleeding. The current literature does not support coagulation screening with APTT in routine perioperative bleeding assessment, as preoperative screening with APTT has a low sensitivity for detection of clinically significant bleeding disorder. While a comprehensive bleeding history is crucial, the APTT test should only be performed on patients with a history of increased bleeding tendency. The conclusion of this literature review is that patients with a negative bleeding history do not require routine screening with APTT prior to surgery, which, if implemented, would lead to a more cost-effective perioperative routine.
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| 10. |
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| 11. |
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| 12. |
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| 13. |
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| 14. |
- Enström, Camilla, et al.
(författare)
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A genotyping method for VKORC1 1173C>T by Pyrosequencing® technology
- 2008
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Ingår i: Scandinavian Journal of Clinical and Laboratory Investigation. - : Informa UK Limited. - 0036-5513 .- 1502-7686. ; 68:5, s. 427-430
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Tidskriftsartikel (refereegranskat)abstract
- Vitamin K epoxide reductase complex subunit 1 (VKORC1) is the site of inhibition by warfarin and other anti-vitamin K drugs during oral anticoagulant therapy. The SNP rs9934438 in intron 1 of VKORC1 (c.173+1000C>T or 1173C>T) discriminating the VKORC1*2 haplotype is associated with low warfarin dose requirement and unstable prothrombin time - international normalized ratio. To genotype this SNP, we have developed a rapid method using Pyrosequencing® technology. The proposed method takes a post-PCR sample preparation of less than 1 h and a DNA sequencing time of less than 15 min to genotype 96 samples. The current method was compared with a dHPLC method that we reported previously. Genotype frequencies at VKORC1 1173C>T for our Swedish population were 38 % wild-type, 40 % heterozygote and 22 % homozygote. The frequency of the T-allele was 0.42, which exactly matches the frequency previously reported for Germans. The current method can be used to determine whether patients initiating warfarin therapy are carriers of SNP 1173 C>T that is strongly associated with low warfarin dose requirement. © 2008 Informa UK Ltd (Informa Healthcare, Taylor & Francis AS).
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| 15. |
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| 16. |
- Hansson, Kenny, 1972-, et al.
(författare)
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Comparative studies with surface plasmon resonance and free oscillation rheometry on the inhibition of platelets with cytochalasin E and monoclonal antibodies towards GPIIb/IIIa
- 2002
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Ingår i: Biosensors & bioelectronics. - 0956-5663 .- 1873-4235. ; 17:9, s. 761-771
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Tidskriftsartikel (refereegranskat)abstract
- In the haemostatic system a multitude of processes are intertwined in fine-tuned interactions that arrest bleeding, keep the circulatory system open, and the blood flowing. The occurrence of both surface and bulk interactions adds an additional dimension of complexity. These insights have led to the belief that global overall procedures can inform on the likely behaviour of the system in health and disease. Two sensing procedures: surface plasmon resonance (SPR), which senses surface interactions, and free oscillation rheometry (FOR), which senses interactions within the bulk, have been combined and evaluated. The contribution of blood cells, mainly platelets, to the SPR and FOR signals was explored by simultaneous SPR and FOR measurement during native whole blood coagulation, accelerated via the platelets through addition of SFLLRN peptide and inhibition of platelet aggregation with abciximab (ReoPro®) and of shape change with cytochalasin E. The SPR technique was found to be sensitive to inhibition of blood cell functions such as adhesion to and spreading on surfaces, as well as platelet aggregation. SPR seemed not to be directly sensitive to fibrin polymerisation in coagulating whole blood. The FOR technique detected the coagulation as a bulk phenomenon, i.e. the gelation of the blood due to fibrin formation was detected. The combination of SPR and FOR may therefore be suitable for studies on blood cell functions during coagulation.
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| 17. |
- Hansson, Kenny, 1972-, et al.
(författare)
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Surface plasmon resonance and free oscillation rheometry in combination : a useful approach for studies on haemostasis and interactions between whole blood and artificial surfaces
- 2002
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Ingår i: Biosensors & bioelectronics. - 0956-5663 .- 1873-4235. ; 17:9, s. 747-759
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Tidskriftsartikel (refereegranskat)abstract
- In haemostatic and biomaterial research biological processes at surfaces and in the bulk phase of the surface-contacting medium are important. The present work demonstrates the usefulness of the combination of surface plasmon resonance (SPR), sensitive to changes in refractive index at surfaces, and free oscillation rheometry (FOR), sensitive to rheological properties of the bulk, for simultaneous real-time measurements on coagulation and fibrinolysis of blood plasma and coagulation of whole blood. SFLLRN stimulated coagulation of native whole blood presented a higher SPR signal with different appearance than plasma coagulation, while the FOR signals corresponding to plasma and whole blood coagulation were similar. This indicated that the SPR technique was more sensitive to cell-surface interactions than to fibrin formation in whole blood during coagulation, while the FOR technique were equally sensitive to coagulation in whole blood and plasma. Spontaneous coagulation of native whole blood in contact with methyl- and hydroxyl-terminated self-assembled monolayers (SAM) on gold and gold surfaces regenerated after coagulation were also studied. The regenerated gold surfaces displayed the shortest coagulation times, although the contact-activation of blood coagulation for these surfaces was low. The methylated and hydroxylated surfaces were comparable in terms of coagulation activation, while the hydroxylated surfaces presented FOR signals that indicated detaching of the coagulum from the surface. The combination of SPR and FOR is well suited for studies of cell– and protein–surface interactions and simultaneous bulk processes. Possible applications are investigations of blood cell defects in patients and monitoring of native whole blood interactions with artificial surfaces.
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| 18. |
- Hansson, Kenny, 1972-, et al.
(författare)
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Surface plasmon resonance detection of blood coagulation and platelet adhesion under venous and arterial shear conditions.
- 2007
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Ingår i: Biosensors & bioelectronics. - : Elsevier BV. - 0956-5663 .- 1873-4235. ; 23:2, s. 261-8
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Tidskriftsartikel (refereegranskat)abstract
- A surface plasmon resonance (SPR) based flow chamber device was designed for real time detection of blood coagulation and platelet adhesion in platelet rich plasma (PRP) and whole blood. The system allowed the detection of surface interactions throughout the 6mm length of the flow chamber. After deposition of thromboplastin onto a section of the sensor surface near the inlet of the flow chamber, coagulation was detected downstream of this position corresponding to a SPR signal of 7 to 8 mRIU (7 to 8 ng/mm2). A nonmodified control surface induced coagulation 3.5 times slower. Platelet adhesion to gold and fibrinogen coated surfaces in the magnitude of 1.25 and 1.66 mRIU was also shown with platelets in buffer, respectively. SPR responses obtained with PRP and whole blood on surfaces that were methylated or coated with von Willebrand factor (vWF), fibrinogen, or collagen, coincided well with platelet adhesion as observed with fluorescence microscopy in parallel experiments. The present SPR detection equipped flow chamber system is a promising tool for studies on coagulation events and blood cell adhesion under physiological flow conditions, and allows monitoring of short-range surface processes in whole blood.
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| 19. |
- Hansson, Kenny, 1972-, et al.
(författare)
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Surface plasmon resonance (SPR) analysis of coagulation in whole blood with application in prothrombin time assay
- 1999
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Ingår i: Biosensors & bioelectronics. - 0956-5663 .- 1873-4235. ; 14:8-9, s. 671-682
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Tidskriftsartikel (refereegranskat)abstract
- It is previously shown that surface plasmon resonance (SPR) can be used to study blood plasma coagulation. This work explores the use of this technique for the analysis of tissue factor induced coagulation, i.e. prothrombin time (PT) analysis, of whole blood and plasma. The reference method was nephelometry. The prothrombin time analysis by SPR was performed by mixing two volumes of blood/plasma, one volume of thromboplastin, and one volume of CaCl2 solution directly on a sensor surface. The measurements show good agreement between nephelometry and SPR plasma analysis and also between SPR plasma and whole blood analysis. The effect of anticoagulant treatment on the clotting times was significant both quantitatively and qualitatively. The impact on the SPR signal of different physiological events in the coagulation process is discussed, and tentative interpretations of the sensorgram features are given. The major advantage of the SPR method compared to nephelometry is the possibility to perform analysis on whole blood instead of plasma. In conclusion, SPR is a promising method for whole blood coagulation analysis.
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| 20. |
- Hansson, Kenny, 1972-, et al.
(författare)
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Whole blood coagulation on protein adsorption-resistant PEG and peptide functionalised PEG-coated titanium surfaces.
- 2005
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Ingår i: Biomaterials. - : Elsevier BV. - 0142-9612 .- 1878-5905. ; 26:8, s. 861-72
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to investigate whole blood coagulation on low blood plasma protein adsorbing surfaces. For this purpose, the polycationic graft copolymer poly(L-lysine)-g-poly(ethylene glycol) (PLL-g-PEG), PLL-g-PEG grafted with a cell adhesive peptide containing the amino acid sequence -Arg-Gly-Asp- (RGD), and PLL-g-PEG with a control peptide -Arg-Asp-Gly- (RDG) were adsorbed onto titanium (oxide), forming stable monomolecular adlayers through electrostatic attraction. Free oscillation rheometry and complementary techniques were used to measure the coagulation time (CT) and other interactions of the surfaces with native whole blood, recalcified platelet-rich plasma (PRP), and recalcified citrated platelet-free plasma (PFP). The results show that the uncoated titanium surfaces (reference) activated platelets and quickly triggered the coagulation cascade via the intrinsic pathway, whereas the PLL-g-PEG surfaces displayed a prolonged CT, approximately 2-3 times longer compared to uncoated titanium. We hypothesise that blood coagulates outside the vascular system independent of low protein adsorption to or activation by surfaces, due to the absence of an active down-regulation of procoagulative processes by the vascular endothelium.
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| 21. |
- Hillarp, Andreas, et al.
(författare)
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Local INR calibration of the Owren type prothrombin assay greatly improves the intra- and interlaboratory variation
- 2004
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Ingår i: Thrombosis and Haemostasis. - 0340-6245 .- 2567-689X. ; 91:2, s. 300-307
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Tidskriftsartikel (refereegranskat)abstract
- In 1999, a simplified procedure for calibration of the Owren prothrombin time (Owren PT) assay was introduced by a working group of the organisation for national quality assurance in laboratory medicine in Sweden. The new protocol allowed local calibration by means of only two lyophilised national plasma calibrators and expression of results as an international normalized ratio (INR). This is our report of a three-year follow-up involving the analysis of data from all laboratories, in hospitals (n=88 in 2002) and primary health care units (n=246 in 2002) that perform the Owren PT assay in Sweden. The interlaboratory variation was significantly improved after the introduction of the new calibration procedure. For the larger hospital-based laboratories, the mean coefficient of variation (CV) was reduced from 7.9% to 5.2% (p<0.0001) when analysing test materials with INR range 2-4. In the higher INR range (>4), the CV was reduced even further, from 10.4% to 6.8% (p<0.0001). The corresponding results from smaller laboratories in the primary health care units showed a similar decrease in CV from 8.2% to 5.7% in the INR range 2-4 (p<0.0001). At the INR range >4, the CV was reduced from 9.5% to 7.8%. The intralaboratory variation was also improved for both types of laboratory categories. This study shows an improved precision, with CV less than 6% at the therapeutic INR range, for both hospital-based laboratories and smaller laboratories in the primary health care system. The results indicate that the Owren PT assay is well suited for local INR calibration employing only two calibrant plasmas in a simplified procedure.
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| 22. |
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| 23. |
- Holm, Jonas, 1971-, et al.
(författare)
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Copeptin Release in Cardiac Surgery : A New Biomarker to Identify Risk Patients?
- 2018
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Ingår i: Journal of Cardiothoracic and Vascular Anesthesia. - : Saunders Elsevier. - 1053-0770 .- 1532-8422. ; 32:1, s. 245-250
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To describe the dynamics of copeptin in open cardiac surgery during the perioperative course.DESIGN: Prospective cohort study.SETTING: Single tertiary hospital.PARTICIPANTS: Twenty patients scheduled for open cardiac surgery procedures with cardiopulmonary bypass (CPB).INTERVENTIONS: No intervention.MEASUREMENTS AND MAIN RESULTS: Copeptin concentrations were measured pre-, peri-, and postoperatively until day 6 after surgery. Patients were analyzed as a whole cohort (n = 20) and in a restricted "normal cohort" consisting of patients with normal preoperative copeptin concentration (<10 pmol/L) and perioperative uneventful course (n = 11). In the whole cohort, preoperative copeptin concentration was 7.0 pmol/L (interquartile range: 3.1-11 pmol/L). All patients had an early rise of copeptin, with 80% having peak copeptin concentration at weaning from CPB or upon arrival in the intensive care unit. Patients in the "normal cohort" had copeptin concentration at weaning from CPB of 194 pmol/L (98-275), postoperative day 1, 27 pmol/L (18-31); and day 3, 8.9 pmol/L (6.3-12).CONCLUSIONS: Regardless of cardiac surgical procedure and perioperative course, all patients had an early significant rise of copeptin concentrations, generally peaking at weaning from CBP or upon arrival in the intensive care unit. Among patients with normal copeptin concentration preoperatively and uneventful course, the postoperative copeptin concentrations decreased to normal values within 3-to-4 days after cardiac surgery. Furthermore, the restricted "normal cohort" generally tended to display lower levels of copeptin concentration postoperatively. Further studies may evaluate whether copeptin can be a tool in identifying risk patients in cardiac surgery.
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| 24. |
- Jackson, Craig M, et al.
(författare)
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A critical evaluation of the prothrombin time for monitoring oral anticoagulant therapy
- 2003
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Ingår i: Pathophysiology of Haemostasis and Thrombosis. - : S. Karger AG. - 1424-8832 .- 1424-8840. ; 33:1, s. 43-51
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Tidskriftsartikel (refereegranskat)abstract
- The Quick prothrombin time is the most common clotting test performed, principally for monitoring oral anticoagulant therapy. The International Normalized Ratio (INR) for comparing patient results from prothrombin time measurements and the International Standardized Index (ISI) for achieving greater consistency of results using different thromboplastins have made it possible to compare the results of vitamin K antagonist drug therapy that was impossible before the introduction of the INR and ISI. However, INR values obtained from the same patient plasma sample using different thromboplastins are significantly different. This is so even when the thromboplastins have nearly the same ISI values. We suggest that investigation of patient-specific differences can provide a means by which the INR discrepancies can be identified and understood and thus lead to better methods for monitoring oral anticoagulant therapy.
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| 25. |
- Jennersjö, Cecilia, 1963-, et al.
(författare)
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Normal D-dimer concentration is a common finding in symptomatic outpatients with distal deep vein thrombosis
- 2005
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Ingår i: Blood Coagulation and Fibrinolysis. - 0957-5235 .- 1473-5733. ; 16:7, s. 517-523
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Tidskriftsartikel (refereegranskat)abstract
- The D-dimer analysis has been shown to have a high sensitivity and a high negative predictive value for the exclusion of deep vein thrombosis (DVT). However, most D-dimer studies, including recent clinical management studies, are performed without examination of the calf veins and/or performed on patient populations with a predominance of proximal DVT. The purpose of this study was to evaluate the diagnostic performance of the D-dimer test in a population with a suspected high incidence of distal DVT. In the present study, 393 outpatients with clinically suspected symptomatic DVT of the lower extremities were examined with whole-leg duplex ultrasonography. The D-dimer analysis was performed using an automated micro-latex assay (Tina-quant). A total of 137 of 393 patients had a proven DVT, with the majority presenting with distal DVT (59%). Twenty-eight out of 81 patients with distal DVT had a normal D-dimer, compared with two of 56 patients with proximal DVT. The sensitivity for distal DVT was only 65% compared with 96% for proximal DVT, the negative predictive values were 84 and 99%, respectively. In conclusion, the prevalence of distal DVT in a study population seems to have a great impact on the diagnostic performance of the D-dimer analysis. The study results also show that normal D-dimer levels do not exclude distal DVT in outpatients, instead, it can be hypothesized that normal D-dimer levels exclude DVT that require treatment, as indicated by the good outcome in recent management studies. © 2005 Lippincott Williams & Wilkins.
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| 26. |
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| 27. |
- Johanson, Per, 1963, et al.
(författare)
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Prognostic value of ST-segment resolution-when and what to measure.
- 2003
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Ingår i: European heart journal. - 0195-668X. ; 24:4, s. 337-45
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Tidskriftsartikel (refereegranskat)abstract
- Analyses of ST-segment resolution during acute myocardial infarction has, during recent years, challenged coronary angiography as gold-standard for predicting myocardial reflow and future risk. We have previously reported that continuous ST-monitoring can be done accurately in the clinical setting. We now set out to compare the prognostic value of previously suggested cut-offs for ST-segment resolution, and determine the times to measure these.
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| 28. |
- Järemo, Petter, et al.
(författare)
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Elevated platelet reactivity in stable angina pectoris without significant coronary flow obstruction
- 2008
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Ingår i: Journal of Cardiovascular Medicine. - : Lippincott Williams & Wilkins. - 1558-2027. ; 9:2, s. 129-130
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND:There are many different causes of angina pectoris without significant coronary flow obstruction in major coronary arteries. Examples include Prinzmetal angina and small vessel atherosclerotic disease.METHODS:We investigated individuals with stable angina pectoris subject to elective coronary angiography. To keep the study group as homogeneous as possible, patients with diabetes mellitus were excluded. Subjects with normal coronary angiograms (n = 13) or insignificant (< 50%) coronary flow obstruction(s) (n = 4) were grouped together. The remaining cohort (n = 96) with at least one significant (> or = 50%) flow obstruction in at least one major coronary artery served as controls.RESULTS:Before angiography, platelet activity in vitro on stimulation with a thrombin-receptor activating peptide (TRAP-6) (57 micromol/l and 74 micromol/l) and ADP (1.7 micromol/l and 8.5 micromol/l) was determined. Angina pectoris individuals without significant flow obstruction in major coronary arteries had enhanced platelet reactivity both when stimulated with TRAP-6 and ADP (P < 0.01 for both TRAP-6 concentrations and P < 0.05 for both ADP concentrations, respectively.CONCLUSIONS:It is concluded that angina pectoris without significant flow impediment in major epicardial arteries is associated with augmented platelet reactivity.
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| 29. |
- Järemo, Petter, et al.
(författare)
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Individual variations of platelet inhibition after loading doses of clopidogrel
- 2002
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Ingår i: Journal of Internal Medicine. - : Wiley. - 0954-6820 .- 1365-2796. ; 252:3, s. 233-238
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Tidskriftsartikel (refereegranskat)abstract
- Objective. To investigate individual variations of platelet inhibition after clopidogrel-loading doses.Setting. Department of Cardiology, Linköping University Hospital, Linköping, Sweden.Subjects. Individuals with stable angina pectoris (n = 18) subject to percutaneous coronary interventions (PCI) and subsequent stenting were investigated.Methods and experimental protocol. A 300-mg clopidogrel loading dose was administrated immediately after stenting (day 1) followed by an additional 75 mg clopidogrel after 24 h (day 2). The ADP-evoked platelet fibrinogen binding was analysed to estimate platelet reactivity immediately before angiography and on day 2. A flow cytometry technique was used with two ADP solutions (final concentrations 0.6 and 1.7 μmol L−1) employed as platelet activating agents. Soluble P-selectin was used as a marker of platelet activity.Results. When using 1.7 μmol L−1 ADP to activate platelets four individuals had a strong inhibition (i.e. platelet reactivity <10% of the day 1-value day 2). In contrast, five patients demonstrated a weak inhibition (i.e. platelet reactivity >60% of the day 1-value day 2). Similar results were obtained when using 0.6 μmol L−1 ADP as a platelet-activating agent. Clopidogrel, however, fails to suppress platelet activity as estimated from soluble P-selectin.Conclusions. Clopidogrel evoked platelet inhibition exhibits a considerable individual heterogeneity. Some individuals only had weak responses whereas others displayed strong platelet inhibition. The present flow cytometry technique appears suitable for identifying patients with abnormal reactions after clopidogrel exposure.
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| 35. |
- Larsson, Anders, et al.
(författare)
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Studies of fibrinogen binding to porcine platelets by flow cytometry : A method for studies of porcine platelet activation
- 2002
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Ingår i: Platelets. - : Informa UK Limited. - 0953-7104 .- 1369-1635. ; 13:3, s. 153-157
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Tidskriftsartikel (refereegranskat)abstract
- Platelets have a central function in haemostasis. They also participate in arterial thrombus formation in vascular disorders. Platelets have an important role in initiating and mediating ischaemia and related complications of ischemic heart disease. Several research groups are thus studying platelet activation and developing new platelet inhibitors. Platelet function is dependent upon membrane receptors and their interaction with other proteins. Binding of fibrinogen to the platelet glycoprotein (GP) IIb/IIIa receptor is a prerequisite for platelet aggregation and thrombus formation. Thus, several GPIIb/IIIa inhibitors have been developed of which abciximab is the clinically most widely used. Pigs are often used for experimental studies. We have developed a flow cytometry assay for measuring porcine platelet activation utilising an FITC-labelled chicken anti-fibrinogen antibody. ADP, ristocetin and thrombin induce fibrinogen binding to porcine platelets similarly to human platelets. Ristocetin induces platelet aggregation and microvesicle formation from porcine platelets as well as from human platelets.
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| 36. |
- Lindahl, Tomas, 1954-, et al.
(författare)
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A new flow cytometric method for measurement of von Willebrand factor activity
- 2003
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Ingår i: Scandinavian Journal of Clinical and Laboratory Investigation. - : Informa UK Limited. - 0036-5513 .- 1502-7686. ; 63:3, s. 217-224
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Tidskriftsartikel (refereegranskat)abstract
- Background: Patients with von Willebrand's disease may have normal levels of von Willebrand factor (VWF) antigen. It is therefore important to measure not only the antigen concentration but also the VWF activity. The most widely used method for measurement of VWF activity is the ristocetin cofactor assay (VWF:RCo), which is still crucial for the laboratory diagnosis of von Willebrand's disease (VWD). However, VWF:RCo has low precision, poor inter-laboratory reproducibility and requires an aggregometer. Many routine laboratories are not equipped with aggregometers but have flow cytometers instead. Methods: In this study a simple, precise and rapid flow cytometric assay was developed for the determination of von Willebrand factor activity, utilizing formalin-fixed platelets, fluorescein isothiocyanate-conjugated chicken anti-VWF antibodies (Fab-fragments) and phycoerythrine-conjugated anti-GPIIb/IIIa antibodies. Results: In samples from healthy controls and from patients with von Willebrand disease type 1, the flow cytometry assay showed good correlation with the VWF:RCo assay (r2 = 0.69) and the VWF antigen assays (r2 = 0.83), which was better than the correlation between the VWF:RCo assay and VWF antigen assays (r2 = 0.72). The flow cytometry method had good within-assay and total precision, C.V. 4,2%, and C.V. 7.5%, at a mean concentration of 0.40 IU/mL, respectively. Results obtained with the flow cytometric method on samples from two patients with von Willebrand disease 2B were lower than those obtained with the antigen method in accordance with the diagnosis. Conclusion: The accuracy and precision of the von Willebrand activity assay may be improved if a flow cytometer is utilized for measurement of the impact of ristocetin on binding of VWF to formalin-fixed platelets instead of measuring agglutination utilizing an aggregometer. In addition, our flow cytometric method assay enables measurement of von Willebrand factor activity at many more hospitals than was previously possible with the traditional ristocetin cofactor platelet aggregometry assay, and this trend is likely to increase in the future when routine hematological instruments are equipped with built-in flow cytometers.
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| 37. |
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| 43. |
- Nylander, Sven, et al.
(författare)
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Evaluation of platelet function, a method comparison
- 2006
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Ingår i: Platelets. - : Informa UK Limited. - 0953-7104 .- 1369-1635. ; 17:1, s. 49-55
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Tidskriftsartikel (refereegranskat)abstract
- Platelet function can be studied using many different methods why it is of interest to understand how data from different assays relate to each other. In the present study we compare two methods suitable for screening purposes with two established although laborious methods, impedance aggregometry and platelet-rich plasma (PRP) aggregation. The alternative assays tested were: (i) exposure of active αIIbβ3, in diluted whole blood and (ii) whole blood aggregation assessed by residual platelet counting. The fibrinogen receptor activation assay was found to have the lower variability, higher sensitivity to ADP, and higher signal to noise ratio compared with residual platelet counting. The sensitivity and response profile of the fibrinogen receptor activation assay and residual platelet counting were more similar to PRP aggregation than to impedance aggregometry, whereas impedance aggregometry displayed lower sensitivity to ADP. The two alternative assays correlated well with PRP aggregation as well as with each other. The fibrinogen receptor activation assay displayed the highest potency for AR-C69931MX, possibly due to a lower protein content compared with residual platelet counting. The two studied assays compare well with the more established assays, and are thus both good alternatives for platelet function testing and evaluation of new potential platelet antagonists.
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| 44. |
- Nylander, Sven, et al.
(författare)
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Synergistic action between inhibition of P2Y12/P2Y1 and P2Y12/thrombin in ADP- and thrombin-induced human platelet activation
- 2004
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Ingår i: British Journal of Pharmacology. - : Wiley. - 0007-1188 .- 1476-5381. ; 142:8, s. 1325-1331
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this study was to investigate if there is a synergistic effect of a combination of P2Y12 and P2Y1 inhibition and P2Y12 and thrombin inhibition, on ADP- and thrombin-induced platelet activation, respectively. The rationale being that these combinations will cause a concurrent inhibition of both Gαq and Gαi signalling.Blood from healthy volunteers was preincubated with AR-C69931MX, a reversible P2Y12 antagonist; MRS2179, a reversible P2Y1 antagonist; or melagatran, a direct reversible thrombin inhibitor; alone or in various combinations prior to activation with ADP or thrombin. Platelet function in whole blood was assessed by flow cytometry using the antibody PAC-1 to estimate the expression of active αIIbβ3 (the fibrinogen receptor GPIIb/IIIa). A synergistic effect was evaluated by comparing the concentrations in the different combinations with those of corresponding equipotent concentrations of each single inhibitor alone. The equipotent single concentrations were experimentally obtained from concentration response curves performed in parallel.A synergistic effect regarding inhibition of ADP-induced platelet activation (10 μM) was obtained with different combinations of AR-C69931MX and MRS2179.Inhibition of thrombin-induced platelet activation (2 nM) with combinations of AR-C69931MX and the thrombin inhibitor melagatran did also result in a strong synergistic effect.To our knowledge, this is the first time that data supporting a synergistic effect has been published for the inhibitor combinations described.Whether this synergistic effect in vitro also results in an improved antithrombotic effect in vivo with or without an increased risk of bleeding remains to be studied in well-conducted clinical studies.
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| 45. |
- Nylander, Sven, et al.
(författare)
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The relative importance of the ADP receptors, P2Y12 and P2Y1, in thrombin-induced platelet activation
- 2003
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Ingår i: Thrombosis Research. - : Elsevier BV. - 0049-3848 .- 1879-2472. ; 111:1-2, s. 65-73
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this study was to test the relative importance of the two adenosine diphosphate (ADP) receptors P2Y1 and P2Y12 in thrombin-induced platelet activation using specific receptor antagonists. Blood from healthy volunteers was incubated with MRS2179, a reversible P2Y1 antagonist, or AR-C69931, a reversible P2Y12 antagonist prior to activation with different concentrations of ADP or thrombin. Platelet function in whole blood was assayed by flow cytometry using the antibody PAC-1 to estimate the expression of conformational active αIIbβ3, the fibrinogen receptor. Complete inhibition of P2Y12 or P2Y1 abolished the ADP response, but only inhibition of P2Y12 reduced the thrombin-induced response. The relative inhibition of the thrombin response by complete inhibition of P2Y12 was most pronounced at thrombin concentrations just enough for complete PAR1 cleavage, which is sufficient to release all ADP, giving 70–86% inhibition. Above this concentration, the relative importance of P2Y12 inhibition decreased due to activation of ADP independent pathways. This study supports P2Y12 as a drug target compared with P2Y1.
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| 46. |
- Ramström, A Sofia, et al.
(författare)
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A flow cytometric assay for the study of dense granule storage and release in human platelets
- 1999
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Ingår i: Platelets. - : Informa Healthcare. - 0953-7104 .- 1369-1635. ; 10:2-3, s. 153-158
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Tidskriftsartikel (refereegranskat)abstract
- The clinical manifestations of platelet dense (δ) granule defects are easy bruising, as well as epistaxis and bleeding after delivery, tooth extractions and surgical procedures. The observed symptoms may be explained either by a decreased number of granules or by a defect in the uptake/release of granule contents. We have developed a method to study platelet dense granule storage and release. The uptake of the fluorescent marker, mepacrine, into the platelet dense granule was measured using flow cytometry. The platelet population was identified by the size and binding of a phycoerythrin-conjugated antibody against GPIb. Cells within the discrimination frame were analysed for green (mepacrine) fluorescence. Both resting platelets and platelets previously stimulated with collagen and the thrombin receptor agonist peptide SFLLRN was analysed for mepacrine uptake. By subtracting the value for mepacrine uptake after stimulation from the value for uptake without stimulation for each individual, the platelet dense granule release capacity could be estimated. Whole blood samples from 22 healthy individuals were analysed. Mepacrine incubation without previous stimulation gave mean fluorescence intensity (MFI) values of 83±6 (mean ± 1 SD, range 69–91). The difference in MFI between resting and stimulated platelets was 28±7 (range 17–40). Six members of a family, of whom one had a known δ-storage pool disease, were analysed. The two members (mother and son) who had prolonged bleeding times also had MFI values disparate from the normal population in this analysis. The values of one daughter with mild bleeding problems but a normal bleeding time were in the lower part of the reference interval.
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| 47. |
- Ramström, Sofia, 1973-, et al.
(författare)
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Effects of inhibition of P2Y1 and P2Y12 on whole blood clotting, coagulum elasticity and fibrinolysis resistance studied with free oscillation rheometry
- 2003
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Ingår i: Thrombosis Research. - 0049-3848 .- 1879-2472. ; 109:5-6, s. 315-322
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: In vivo, initial platelet activation is likely caused by platelet contacts with collagen in the subendothelium or from the small amounts of thrombin formed by the tissue factor/factor VIIa complex. Our aim was to study the coagulative role of ADP released by the platelets after activation with strong stimuli such as collagen and/or thrombin, and the relative importance of the platelet ADP receptors P2Y1 and P2Y12.Materials and methods: We used 10 Hz free oscillation rheometry to measure clotting time, clot elasticity and fibrinolysis resistance of non-anticoagulated whole blood. The platelets were activated with a collagen-related peptide (CRP), with the PAR1 thrombin receptor activating peptide TRAP-6 or by thrombin, the latter generated by small amounts of thromboplastin. To inhibit the platelet ADP receptors, we used the P2Y1 antagonist MRS2179 and the P2Y12 antagonist AR-C69931MX.Results: Both antagonists significantly retarded the clotting induced by CRP. The effects were most pronounced with AR-C69931MX. For TRAP-6, the same trend was seen, but the retardation was only significant with AR-C69931MX. Clotting induced by small amounts of thromboplastin was not affected by any ADP-receptor antagonist. Addition of both antagonists did not change the results as compared to samples with AR-C69931MX alone. Nor did the antagonists, one at a time or in concert, effect fibrinolysis or the elastic properties of the clot.Conclusion: We conclude that ADP-receptor inhibition prolongs the clotting time for whole blood activated by CRP, but that it does not affect the properties of the subsequently formed coagulum.
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| 48. |
- Ramström, Sofia, 1973-, et al.
(författare)
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Platelet PAR1 receptor density-Correlation to platelet activation response and changes in exposure after platelet activation
- 2008
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Ingår i: Thrombosis Research. - : Elsevier BV. - 0049-3848 .- 1879-2472. ; 121:5, s. 681-688
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: A polymorphism (-14 A/T) affecting PAR1 expression on the platelet surface has recently been identified. A two-fold variation in receptor density, which correlated with the platelet response to PAR1-activating peptide (PAR1-AP), has been reported. Materials and methods: We used flow cytometry to measure the correlation between the number of PAR1 receptors and platelet activation. We also measured the changes in receptor exposure after platelet activation with PAR1-AP, ADP, PAR4-AP or a collagen-related peptide (CRP). Results: In our study, the PAR1 receptor number varied almost four-fold, from 547 to 2063 copies/platelet (mean ± S.D. 1276 ± 320, n = 70). The number of PAR1 receptors on resting platelets correlated to platelet fibrinogen binding and P-selectin expression following platelet activation with PAR1-AP (r2 = 0.30, p < 0.01 and r2 = 0.15, p < 0.05, respectively, n = 36). The correlation was not improved by exclusion of the ADP-component from the PAR1-AP-induced response. We found a trend, but no statistically significant differences in PAR1 receptor number and platelet reactivity between A/A individuals and T/A or T/T individuals. Ex vivo activation with PAR1-AP decreased PAR1 surface exposure to 71 ± 19% of the exposure on resting platelets (mean ± S.D., p < 0.01, n = 19), while activation by ADP, PAR4-AP or CRP significantly increased the exposure, to 151 ± 27%, 120 ± 21% and 138 ± 25%, respectively (n = 11, 11 and 10). Conclusions: This study shows a large variation in PAR1 receptor number in healthy individuals, a variation correlated to the platelet activation response. We found a significant reduction in PAR1 surface exposure after adding PAR1-AP, while activation with ADP, PAR4-AP or CRP increased the exposure.
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| 49. |
- Ramström, Sofia, 1973-, et al.
(författare)
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Platelet phosphatidylserine exposure and procoagulant activity in clotting whole blood : different effects of collagen,TRAP and calcium ionophore A23187
- 2003
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Ingår i: Thrombosis and Haemostasis. - 0340-6245 .- 2567-689X. ; 89:1, s. 132-141
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Tidskriftsartikel (refereegranskat)abstract
- We have studied the effects of different platelet agonists onphosphatidylserine (PS) exposure and clotting times in bloodwithout anticoagulants. Similar reductions in clotting time wereobtained for collagen, TRAP-6 or calcium ionophore A23187(50 µmol/L), in spite of huge differences in PS expression[6.7 ± 2.4%, 2.3 ± 0.5% and 99.9 ± 0.1%, respectively (mean ±SD, n = 5)]. Furthermore, the clotting times were much longerfor samples with A23187 exposing the same amounts of PS assamples with collagen or TRAP-6. Annexin V reversed theclotting time reduction, but could not prevent coagulation.Addition of phospholipid vesicles containing 20% PS neitheraffected the clotting times nor induced clotting in recalcified,platelet-free plasma.We conclude that platelet PS exposure is necessary, but notsufficient, for the coagulation amplification observed whenplatelets are stimulated via physiological receptors in a wholeblood environment.
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| 50. |
- Ramström, Sofia, 1973-, et al.
(författare)
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The role of platelets in blood coagulation : effects of platelet agonists and GPIIb/IIIa inhibitors studied by free oscillation rheometry
- 2002
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Ingår i: Thrombosis Research. - 0049-3848 .- 1879-2472. ; 105:2, s. 165-172
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Tidskriftsartikel (refereegranskat)abstract
- We have studied the contribution of platelets to the coagulation of plasma and the effects of activation or inhibition of platelets on the coagulation process in unanticoagulated fresh whole blood (subsequently termed native blood). For this purpose, we have used a free oscillation rheometer (FOR), the ReoRox4, a new instrument that enables noninvasive viscoelastic measurements of clot formation in plasma and whole blood. Platelets appear essential for the initiation of coagulation if no activating surface is present. We prepared platelet-free plasma by quick centrifugation and filtration of native blood, which did not coagulate if stored in plastic containers at 37 °C but clotted if transferred to glass containers. Addition of platelet agonists, such as collagen or the thrombin receptor agonist peptide, SFLLRN, significantly accelerated the clotting of native blood and also changed the rheometer curve appearance, accelerating both onset and completion of clot formation (i.e. fibrin gel formation). Inhibition of platelet glycoprotein (GP) IIb/IIIa with the peptide-derived compound MK-852 or the antibody-derived abciximab (Reopro) prevented clot retraction and prolonged the clotting time with SFLLRN. In collagen-stimulated samples, MK-852 accelerated clotting but delayed completion of clotting while abciximab prolonged both clotting time and completion of clotting. To our knowledge, this is the first report showing that activation of platelets in native whole blood shortens the coagulation time ex vivo. It also describes a new instrument that enables studies of the viscoelastic properties of a forming whole blood clot.
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