Stine Bjørnsen

No case of COX-1-related aspirin resistance found in 289 patients with symptoms of stable CHD remitted for coronary angiography.

Objective. To assess the prevalence of a lacking aspirin effect on cyclooxygenase‐1 (COX‐1) (“aspirin resistance”) in patients with symptomatic, stable coronary heart disease (CHD) using test methods directly reflecting inhibition of COX‐1. Material and methods. Arachidonic acid (AA)‐induced platelet aggregation and plasma thromboxane B2 (TXB2) were determined twice 3 weeks apart – prior to elective coronary angiography – in 289 patients on 75 or 160 mg aspirin daily, all prompted to take aspirin before testing. Subjects who demonstrated lacking any effect of aspirin (⩾20 % AA‐induced aggregation) on one or both occasions were later given a third test. Forty‐two patients not taking aspirin were used as TXB2 controls. Results. Eleven (3.8 %) had aggregation ⩾20 % in at least one of the two initial tests, but only two on both occasions. During the third test, all 11 patients had aggregation <20 %. The TXB2 distributions in controls and study patients differed markedly (mean 173 versus 19 pg/mL). Taking 45 pg/mL as the TXB2 cut‐off level, sensitivity and specificity for detecting subjects taking aspirin were 90 % and 89 %, respectively. The area under the ROC curve was 0.96. Conclusion. Repeated AA‐induced platelet aggregometry showed that COX‐1 could be blocked by low‐dose aspirin in all 289 tested patients, suggesting that aspirin resistance is rare in patients with stable CHD.

Assessment of heparin anticoagulation: comparison of two commercially available methods

BACKGROUND The activated clotting time is a bedside method routinely used to monitor heparin anticoagulation during operations requiring cardiopulmonary bypass. The thrombolytic assessment system heparin management test is a new bedside method for monitoring heparin effect. We compared these methods with respect to their ability to reflect the actual heparin concentration in plasma determined by an anti-FXa method. METHODS Two studies were done, an ex vivo study on ten patients who had coronary artery bypass using non-heparin-coated cardiopulmonary bypass circuits and full systemic heparinization and an in vitro study on single donor plasma spiked with heparin 0 to 10 IU/mL. RESULTS Ex vivo study correlation coefficients of activated clotting time and the thrombolytic assessment system heparin management test clotting times versus anti-FXa-based heparin assay were low (r = 0.53, p = 0.002/r = 0.64, p<0.001) in contrast with the corresponding correlation coefficients for the in vitro study (r = 0.98, p<0.001/r = 0.99, p<0.001). A substantial variability in duplicate activated clotting time determinations was noted, which was less pronounced with the thrombolytic assessment system heparin management test. CONCLUSIONS The thrombolytic assessment system method does not correlate better to the actual amount of heparin during cardiopulmonary bypass procedures than the activated clotting time method, which should be performed in duplicate.

Fibrinolytic activity and postoperative salvaged untreated blood for autologous transfusion in major orthopaedic surgery

OBJECTIVE To evaluate the fibrinolytic activity in a closed surgical wound, in postoperatively drained blood, and during autologous transfusion. DESIGN Prospective study. SETTING National hospital, Norway. PATIENTS 9 patients operated on for thoracic scoliosis. MAIN OUTCOME MEASURE Concentrations of plasmin/antiplasmin (PAP), alpha2-antiplasmin, and D-dimers in drained, arterial, and mixed venous blood before, during, and after infusion of 10 ml/kg body weight of postoperatively drained, untreated blood. RESULTS In drained blood the concentration of alpha2-antiplasmin was 31% of the preoperative arterial control value. Together with the increased concentrations of PAP to 18076 microg/L and D-dimers to 126 mg/L, this indicates extensive fibrinolytic activity in the closed wound. The postoperative autologous transfusion of drained, untreated blood increased the concentration of PAP from 507 to 2453 microg/L and of D-dimer from 0.7 mg/L to 15.3 mg/L in systemic blood. CONCLUSION The systemic concentration of fibrin(ogen) degradation products, indicated by D-dimers, after recirculation of drained, untreated blood might impair coagulation. The extensive activation of plasmin might exhaust available alpha2-antiplasmin in the wound and result in postoperative rebleeding.

Systemic biomarkers of inflammation and haemostasis in patients with chronic necrotizing pulmonary aspergillosis.

BackgroundThe purpose of this study was to investigate mediators of inflammation and haemostasis in patients with chronic necrotizing pulmonary aspergillosis (CNPA), a locally, destructive process of the lung due to invasion by Aspergillus species.MethodsMeasurements of selected biomarkers in 10 patients with CNPA and 19 healthy, matched controls were performed with enzyme-linked immunosorbent assay (ELISA) and multiplex methodology. The gene expressions of relevant biomarkers were analyzed with real-time quantitative RT-PCR.ResultsIncreased concentrations of circulating mediators of inflammation interleukin (IL)-6, IL-8, RANTES, TNF-α, ICAM-1 and mediators involved in endothelial activation and thrombosis (vWF, TF and PAI-1) were observed in patients with CNPA. The concentration of the anti-inflammatory cytokine IL-10 was increased both in plasma and in PBMC in the patient population. The gene expression of CD40L was decreased in PBMC from the patient group, accompanied by decreased concentrations of soluble (s) CD40L in the circulation.ConclusionsThe proinflammatory response against Aspergillus may be counteracted by reduced CD40L and sCD40L, as well as increased IL-10, which may compromise the immune response against Aspergillus in patients with CNPA.

Variability in aggregometry response before and after initiation of clopidogrel therapy.

Abstract Background: Evaluation of clopidogrel therapy by in vitro methods has limitations which may be of clinical importance. We wanted to explore the variability in aggregometry response in aspirin sensitive patients before and after initiation of clopidogrel therapy. Methods: ADP 9.37 μM, AA 1.2mM and TRAP 25mM stimulated light transmissions aggregometry (LTA) were performed twice before (Exams 1 and 2; 3 weeks apart)-and within one year after-initiation of clopidogrel therapy (Exam 3) in 79 patients treated with PCI. Repeated ADP aggregometry was also performed in 16 healthy volunteers in order to estimate LTA measurement error. Result:. Inter-individual differences in ADP aggregation e.g. at Exam 1 were substantial (range 17–77%, SD 15.8%). Intra-individual changes between Exams 1 and 2 were significant (−27 to +36%, SD 14.6%, p<0.05). Inter-individual differences at Exam 3 (on clopidogrel treatment) were larger than expected from Exams 1 and 2 (p<0.01). AA aggregation was the same before and during clopidogrel treatment. In controls, inter-individual differences were smaller at ADP 10 than at ADP 5μM. Conclusions. Inter-individual differences in ADP aggregation were significant both before and during clopidogrel therapy, and there were significant intra-individual variations over time. Therefore, prediction of aggregometry response before or during clopidogrel therapy based on single tests may be unreliable. Inter-individual differences in healthy controls are smaller at high concentrations of ADP, and comparisons of aggregometry response should be performed with caution unless ADP concentrations are standardized.

Thrombin generation and platelet activation related to subintimal percutaneous transluminal angioplasty

Abstract Objective: The purpose of this study was to measure the in vivo platelet activation and thrombin generation in arterial blood after passing a subintimal conduit. Methods: Subintimal percutaneous transluminal angioplasty (SPTA) is a technique where a subintimal channel is created, allowing recanalization of long peripheral arterial occlusion. From 10 patients with intermittent claudication, undergoing successful SPTA for femoropopliteal occlusive disease, we collected antecubital venous blood samples immediately before treatment, preprocedural arterial blood samples taken at the entry level proximal to the vessel occlusion, and subsequently at the reentry level after successful recanalization. Venous follow-up blood samples were taken after 24 hours. Plasma concentrations of β-thromboglobulin (β-TG), RANTES, and Prothrombin fragment (F1 + 2), were determined by immunoassay. Fibrinogen binding to platelets, leukocyte-platelet adhesion, and P-selectin were determined by flow cytometry. Results: We found a statistically significant transluminal increase in the plasma concentrations of RANTES, β-TG and F1 + 2 (p = 0.002, 0.001 and 0.001 respectively), which all normalized within 24 hours. Platelet-leukocyte aggregates significantly decreased after 24 hours compared with preprocedural and preentry levels (3.26% versus 5.26 %, p = 0.017). P-selectin expression on circulating platelets was statistically significantly increased in the blood sample taken at the re-entry level compared with the pre-procedural and pre-entry level (p = 0.007). After 24 hours there was no statistically significant difference to pre-procedural levels. There was no significant change in platelet fibrinogen binding at any levels. Conclusion: When passing a subintimal conduit, in vivo sampled blood demonstrated an extremely rapid and substantial uniform platelet activation and thrombin generation.

Cross-linked αsγt-chain hybrids in plasma clots studied by 1D- and 2D electrophoresis and western blotting

Fibrinogen and fibrin related chains in reduced human plasma as well as the bonds interlinking partially cross-linked fibrin from plasma clots have been studied by means of 1D- and 2D electrophoresis and Western blotting. Immunovisualization of reduced plasma or partially cross-linked fibrin with monoclonal antibodies specific for the α-chains or the γ-chains have shown that several bands represent material belonging to both chains. In order to decide whether these bands constitute αγ-chain hybrids or superimposed α- and γ-chain dimers, the cross-linked material was separated according to both isoelectric point (pI) and molecular weight (MW) using Pharmacias Multiphor II system