Publications by authors named "Esther R van Bladel"

6 Publications

  • Page 1 of 1

Platelet degranulation and glycoprotein IIbIIIa opening are not related to bleeding phenotype in severe haemophilia A patients.

Thromb Haemost 2014 Jun 30;111(6):1022-30. Epub 2014 Jan 30.

Mark Roest, Department of Clinical Chemistry and Hematology, University Medical Center Utrecht, Heidelberglaan 100 (G03.550), 3584 CX Utrecht, The Netherlands, Tel.: +31 88 7555555, Fax: +31 88 7555418, E-mail:

Recently we reported data suggesting that platelets could compensate for the bleeding phenotype in severe haemophilia A (HA). The aim of this study was to confirm these results in a larger population with a detailed characterisation of clinical phenotype. Patients with diagnostic severe HA (FVIII:C <1%) were scored for clinical phenotype by integrating data on age at first joint bleed, joint damage, bleeding frequency and FVIII consumption. Phenotype was defined as onset of joint bleeding-score + arthropathy-score + joint bleeding-score + (2* treatment intensity-score). After a washout period of three days, blood was collected for measurement of basal level of platelet activation, platelet reactivity, endothelial cell activation and presence of procoagulant phospholipids in plasma. Thirty-three patients with severe HA were included, 13 patients with a mild, 12 patients with an average and eight patients with a severe clinical phenotype. No relevant differences in basal level of platelet activation, platelet reactivity, endothelial cell activation and procoagulant phospholipids between all three groups were observed. The mean annual FVIII consumption per kg did not correlate with the platelet P-selectin expression and glycoprotein (GP)IIbIIIa activation on platelets. In conclusion, variability in clinical phenotype in patients with diagnostic severe HA is not related to platelet activation or reactivity, measured as platelet degranulation and platelet GPIIbIIIa opening.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1160/TH13-07-0546DOI Listing
June 2014

Functional platelet defects in children with severe chronic ITP as tested with 2 novel assays applicable for low platelet counts.

Blood 2014 Mar 2;123(10):1556-63. Epub 2014 Jan 2.

Department of Clinical Chemistry and Hematology, University Medical Center Utrecht, Utrecht, The Netherlands;

Immune thrombocytopenia (ITP) is an autoimmune disease with a complex heterogeneous pathogenesis and a bleeding phenotype that is not necessarily correlated to platelet count. In this study, the platelet function was assessed in a well-defined cohort of 33 pediatric chronic ITP patients. Because regular platelet function test cannot be performed in patients with low platelet counts, 2 new assays were developed to determine platelet function: first, the microaggregation test, measuring in platelets isolated from 10 mL of whole blood the platelet potential to form microaggregates in response to an agonist; second, the platelet reactivity assay, measuring platelet reactivity to adenosine diphosphate (ADP), convulxin (CVX), and thrombin receptor activator peptide in only 150 μL of unprocessed whole blood. Patients with a severe bleeding phenotype demonstrated a decreased aggregation potential upon phorbol myristate acetate stimulation, decreased platelet degranulation following ADP stimulation, and a higher concentration of ADP and CVX needed to activate the glycoprotein IIbIIIa complex compared with patients with a mild bleeding phenotype. In conclusion, here we have established 2 functional tests that allow for evaluation of platelet function in patients with extremely low platelet counts (<10(9)). These tests show that platelet function is related to bleeding phenotype in chronic ITP.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1182/blood-2013-08-519686DOI Listing
March 2014

Platelets of patients with chronic kidney disease demonstrate deficient platelet reactivity in vitro.

BMC Nephrol 2012 Sep 28;13:127. Epub 2012 Sep 28.

Department of Clinical Chemistry and Hematology, University Medical Center Utrecht, Heidelberglaan 100, 3584, CX, Utrecht, The Netherlands.

Background: In patients with chronic kidney disease studies focusing on platelet function and properties often are non-conclusive whereas only few studies use functional platelet tests. In this study we evaluated a recently developed functional flow cytometry based assay for the analysis of platelet function in chronic kidney disease.

Methods: Platelet reactivity was measured using flow cytometric analysis. Platelets in whole blood were triggered with different concentrations of agonists (TRAP, ADP, CRP). Platelet activation was quantified with staining for P-selectin, measuring the mean fluorescence intensity. Area under the curve and the concentration of half-maximal response were determined.

Results: We studied 23 patients with chronic kidney disease (9 patients with cardiorenal failure and 14 patients with end stage renal disease) and 19 healthy controls. Expression of P-selectin on the platelet surface measured as mean fluorescence intensity was significantly less in chronic kidney disease patients compared to controls after maximal stimulation with TRAP (9.7 (7.9-10.8) vs. 11.4 (9.2-12.2), P=0.032), ADP (1.6 (1.2-2.1) vs. 2.6 (1.9-3.5), P=0.002) and CRP (9.2 (8.5-10.8) vs. 11.5 (9.5-12.9), P=0.004). Also the area under the curve was significantly different. There was no significant difference in half-maximal response between both groups.

Conclusion: In this study we found that patients with chronic kidney disease show reduced platelet reactivity in response of ADP, TRAP and CRP compared to controls. These results contribute to our understanding of the aberrant platelet function observed in patients with chronic kidney disease and emphasize the significance of using functional whole blood platelet activation assays.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/1471-2369-13-127DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3473261PMC
September 2012

Up-regulation of platelet activation in hemophilia A.

Haematologica 2011 Jun 21;96(6):888-95. Epub 2011 Mar 21.

Department of Clinical Chemistry and Hematology/Van Creveldlaboratory, University Medical Center Utrecht, Heidelberglaan 100 (G03.550), 3584 CX Utrecht, The Netherlands.

Background: Platelets are an underappreciated factor in the classification of the bleeding tendency of patients with hemophilia. In this cross-sectional study, we investigated platelet activation status and responsiveness in relation to residual factor VIII activity and, within the group with severe hemophilia (<1% residual factor VIII activity), to annual factor VIII consumption.

Design And Methods: Twenty-one patients with mild-moderate hemophilia A, 13 with severe hemophilia A and 21 healthy controls were studied. The basal level of platelet activation and platelet responsiveness to activation and inhibition were determined by the measurement of platelet P-selectin expression and soluble platelet activation markers.

Results: Patients with severe hemophilia A had a higher percentage of activated platelets at baseline (15.9%) when compared to patients with mild-moderate hemophilia A (8.2%, P=0.014) and controls (6.4%, P<0.001). Both patients with mild-moderate hemophilia A and those with severe hemophilia A had higher levels of the soluble platelet activation markers platelet factor 4 (1.4 and 1.8 pg/10(6) platelets), CXCL7 (65.8 and 48.2 pg/10(6) platelets) and RANTES (12.8 and 9.5 pg/10(6) platelets), compared to controls (platelet factor 4: 0.3 pg/10(6) platelets, P<0.001 and <0.001; CXCL7 20.0 pg/10(6) platelets, P<0.001 and <0.001; RANTES 4.5 pg/10(6) platelets, P<0.001 and =0.003, respectively). In support of these observations, we found clinical evidence that higher platelet P-selectin expression correlates with lower factor VIII consumption in patients with severe hemophilia (Spearman's r -0.65, P=0.043).

Conclusions: This study indicates that platelets from patients with severe hemophilia A are in a pre-activated state and that this pre-activated state is associated with factor VIII consumption.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3324/haematol.2011.042663DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3105651PMC
June 2011

Out of hospital anticoagulant therapy in patients with acute pulmonary embolism is frequently practised but not perfect.

Thromb Res 2010 Dec;126(6):481-5

Department of Internal Medicine, University Medical Centre Utrecht, Utrecht, The Netherlands.

Introduction: Traditionally, patients with pulmonary embolism (PE) are treated in-hospital until they reach an adequate international normalized ratio (INR). Analogous to patients with a deep venous thrombosis, therapy with low-molecular-weight heparin facilitates out of hospital treatment of PE. We retrospectively analysed the current practice of early anticoagulant therapy in 86 acute PE patients with emphasis on the occurrence and safety of outpatient treatment.

Methods: Data were collected from two large regional teaching hospitals and from a specialized anticoagulation clinical, where patients were followed in the period after hospital discharge. The course of hospitalization and LMWH transitioning therapy and the quality of treatment in the first three months after diagnosis were compared between patients discharged before and patients discharged after reaching adequate INR.

Results: Forty-four patients (51.2%) were discharged early, before reaching an adequate INR, and 42 patients (48.8%) were discharged after reaching adequate INR. Early discharged patients needed more time to reach adequate INR compared to other patients (13 versus 6 days). In 28 patients (32.6%), the LMWH transitioning therapy was stopped prematurely; 21 patients were from the early discharged group. During the first 3 months, the mean individual times below, in and above the INR range were equal between the two groups.

Conclusion: Enhanced compliance to existing guidelines and tools, and further development of guidelines, with focus on intensification of monitoring of INR values in an outpatient setting and preventing premature discontinuation of transitioning therapy, are warranted for a safe and early discharge of stable patients with PE.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.thromres.2010.08.019DOI Listing
December 2010

Risk stratification of patients with pulmonary embolism based on pulse rate and D-dimer concentration.

Thromb Haemost 2009 Oct;102(4):683-7

Department of Internal Medicine, University Medical Centre Utrecht, P.O. Box 85500, 3508 AB Utrecht, the Netherlands.

To enable outpatient treatment of a selected group of patients with pulmonary embolism (PE), insight in the determinants of adverse clinical outcome is warranted. We have identified risk factors for serious adverse events (SAE) within the first 10 days of acute PE. We have retrospectively analysed data of 440 consecutive patients with acute PE. Collected data included age, gender, medical history, blood pressure, pulse rate and D-dimer concentration. The variables associated with SAE in the first 10 days in univariate analysis (p<0.15) have been included in a multivariate logistic regression model (backward conditional, p out >0.10). In 440 patients with acute PE, 20 SAEs occurred in a 10-day follow-up period. Pulse rate > or = 100 beats per minute (bpm) (OR, 6.85; 95%CI 1.43-32.81) and D-dimer concentration > or = 3,000 microg/ml (OR, 5.51; 95%CI 0.68-44.64) were significantly related to the SAEs. All SAEs were predicted by a pulse rate > or = 100 bpm and/or a D-dimer concentration > or = 3,000 microg/ml. Older age, gender, history of venous thromboembolism (VTE), heart failure, chronic obstructive pulmonary disease, cancer or a systolic blood pressure < 90 mm Hg had no significant influence on short term SAEs. Pulse rate and D-dimer concentration can be used to identify patients with acute PE, who are at risk for adverse clinical outcome during the first 10 days of hospitalisation. Outpatient treatment of PE-patients with a pulse rate > or = 100 bpm and/or a D-dimer concentration > or = 3,000 microg/ml has to be discouraged.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1160/TH09-04-0229DOI Listing
October 2009