Publications by authors named "Saskia E M Schols"

22 Publications

  • Page 1 of 1

Validation of PROMIS Profile-29 in adults with hemophilia in the Netherlands.

J Thromb Haemost 2021 Jul 10. Epub 2021 Jul 10.

Department of Clinical Epidemiology, Leiden University Medical Center, Leiden, The Netherlands.

Background: The Patient-Reported Outcomes Measurement Information System (PROMIS) Profile-29 questionnaire is widely used worldwide, but it has not yet been validated in the Netherlands, nor in persons with hemophilia.

Objective: To validate the Dutch-Flemish version of the PROMIS-29 Profile v2.01 in adults with hemophilia.

Methods: Dutch males with hemophilia (all severities) completed questionnaires that contained sociodemographic and clinical characteristics, the PROMIS-29, RAND-36, and the Hemophilia Activities List (HAL). Structural validity of each subscale was assessed with confirmatory factor analysis (CFA). Internal consistency was calculated for each subscale with sufficient model fit in CFA. Construct validity was assessed by testing hypotheses about (1) correlations of each PROMIS-29 subscale with corresponding scales of RAND-36 and domains of HAL, and (2) mean differences in T-scores between subgroups with different hemophilia severities, self-reported joint impairment, and HIV infection status. We considered ≥75% of data in accordance with the hypotheses evidence for construct validity.

Results: In total, 770 persons with hemophilia participated in this cross-sectional study. CFA revealed sufficient structural validity for five subscales: Physical Function, Depression, Sleep Disturbance, Ability to Participate in Social Roles and Activities, and Pain Interference. Internal consistency was high and Cronbach's alpha ranged from 0.79 for Sleep Disturbance to 0.96 for Pain Interference. Differences between clinical subgroups were in the expected direction. Construct validity was confirmed for Physical Function, Anxiety, Depression, Fatigue, Sleep Disturbance, and Pain Intensity.

Conclusion: This study revealed sufficient evidence for structural validity, internal consistency, and construct validity for most PROMIS Profile-29 subscales among people with hemophilia in the Netherlands.
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http://dx.doi.org/10.1111/jth.15454DOI Listing
July 2021

Similar sports participation as the general population in Dutch persons with haemophilia; results from a nationwide study.

Haemophilia 2021 Sep 19;27(5):876-885. Epub 2021 Jun 19.

Van Creveldkliniek, University Medical Center Utrecht, Utrecht, The Netherlands.

Introduction: Although sports participation is advocated in people with haemophilia (PWH), detailed data concerning sports participation in Dutch PWH is lacking.

Aim: to assess sports participation in Dutch PWH (6-65 years) compared to the Dutch general population (GP).

Methods: Data from a nationwide, cross-sectional study in PWH were analysed. Sports participation (type, duration, frequency) was assessed by the Modifiable Activities Questionnaire (MAQ), limitations in activities using the (Paediatric) Haemophilia Activities List ((Ped)HAL). Sports in the two highest categories according to the National Hemophilia Foundation classification were considered high-risk sports. Groups were compared using Chi-square testing.

Results: A total of 524 Adult PWH (median age: 45 (IQR: 30-55); 37% severe) and 126 paediatric PWH (median age: 11 (IQR: 8-14); 52% severe) were included. Sports participation was higher in adults (70%) than the GP (58%) and similar to the GP in children (PWH: 68%, GP: 72%). High-risk sports participation decreased with age in PWH: from 65% (6-12 years) to 17% (50-65 years), which was also observed in the GP. Sports participation in children was independent of severity (non-severe: 67% vs. severe: 65%; P = 0.97), but not in adults (non-severe: 75%, severe: 62%; P < 0.01). Non-severe PWH played more high-risk sports than severe PWH: children at 65% vs. 48% (P = 0.05), adults at 25% vs. 15% (P = 0.07).

Discussion: These results suggest that sports participation in PWH was comparable to the GP. Sports participation was dependent of haemophilia severity in adults. Children were more involved in high-risk sports than adults. More studies on sports-related injury-risk are needed for adequate counselling.
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http://dx.doi.org/10.1111/hae.14366DOI Listing
September 2021

Health and treatment outcomes of patients with hemophilia in the Netherlands, 1972-2019.

J Thromb Haemost 2021 Jun 12. Epub 2021 Jun 12.

Department of Clinical Epidemiology, Leiden University Medical Center, Leiden, the Netherlands.

Introduction: We conducted six cross-sectional nationwide questionnaire studies among all patients with hemophilia in the Netherlands from 1972 until 2019 to assess how health outcomes have changed, with a special focus on patients >50 years of age.

Methods: Data were collected on patient characteristics, treatment, (joint) bleeding, joint impairment, hospitalizations, human immunodeficiency virus and hepatitis C infections, and general health status (RAND-36).

Results: In 2019, 1009 patients participated, of whom 48% had mild, 15% moderate, and 37% severe hemophilia. From 1972 to 2019, the use of prophylaxis among patients with severe hemophilia increased from 30% to 89%. Their median annual bleeding rate decreased from 25 to 2 bleeds. Patients with severe hemophilia aged <16 years reported joint impairment less often over time, but in those aged >40 years joint status did not improve. In 2019, 5% of all 1009 patients were positive for the human immunodeficiency virus. The proportion of patients with an active hepatitis C infection drastically decreased from 45% in 2001 to 2% in 2019 due to new anti-hepatitis C treatment options. Twenty-five percent had significant liver fibrosis even after successful therapy. Compared to the general male population, patients aged >50 years reported much lower scores on the RAND-36, especially on physical functioning.

Discussion/conclusion: Our study shows that increased use of prophylactic treatment and effective hepatitis C treatment have improved joint health and nearly eradicated hepatitis C infection in patients with hemophilia in the Netherlands. However, patients still suffer from hemophilia-related complications, especially patients aged >50 years.
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http://dx.doi.org/10.1111/jth.15424DOI Listing
June 2021

Adherence to prophylaxis and its association with activation of self-management and treatment satisfaction.

Haemophilia 2021 Jul 21;27(4):581-590. Epub 2021 May 21.

Van Creveldkliniek, University Medical Center Utrecht, University Utrecht, Utrecht, the Netherlands.

Introduction: Prophylactic replacement therapy (prophylaxis) in patients with haemophilia (PWH) requires lifelong, frequent (self)infusions. Prophylaxis effectiveness depends on adherence, and the drivers of treatment adherence among PWH are unclear.

Aim: To quantify prophylaxis adherence and associations between adherence and patients' treatment attitudes and satisfaction in a large cohort of children and adults with haemophilia.

Methods: In a nationwide, cross-sectional, questionnaire-based study, PWH with complete information currently using prophylaxis were selected. Validated Hemophilia Regimen Treatment Adherence Scale-Prophylaxis (VERITAS-Pro; normalised score range: 0-100, optimum 0) measured treatment adherence; the Patient Activation Measure (PAM-13; total score range 0-100, optimum 100) measured activation of self-management; Hemophilia Patient Satisfaction Scale (Hemo-Sat; range 0-100, optimum 0) measured treatment satisfaction. Groups were compared according to age (children: <12 years; adolescents: 12-18 years; adults >18 years) and adherence levels using non-parametric tests, and correlations were assessed using Spearman's rho.

Results: Among 321 participants (median age 33 years, interquartile range [IQR]:15-54 years), adherence was high (median VERITAS-Pro total score 17, 89% adherent) but worsened with age, with median scores of 5, 14 and 20 in children, adolescents, adults, respectively (p < .001). Attitudes towards treatment (median 66 vs. 68) participants and treatment satisfaction (12 vs. 10) were similar between adherent and non-adherent patients. The VERITAS-Pro total score was moderately correlated with PAM-13 (r = .41) but not with Hemo-Sat (r = -.11).

Discussion: Prophylaxis adherence was high (89%) but decreased significantly with age and was not correlated with treatment attitude or treatment satisfaction.
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http://dx.doi.org/10.1111/hae.14333DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8362086PMC
July 2021

The potential of individualized dosing of ravulizumab to improve patient-friendliness of paroxysmal nocturnal haemoglobinuria treatment at reduced costs.

Br J Clin Pharmacol 2021 Aug 23;87(8):3359-3363. Epub 2021 Feb 23.

Department of Pharmacy, Radboud Institute for Health Sciences, Radboud University Medical Centre, Nijmegen, The Netherlands.

Ravulizumab is a very expensive complement C5-inhibitor for the treatment of paroxysmal nocturnal haemoglobinuria, with a fixed-dosing interval of 8 weeks. For lifelong treatment, a cost-effective and patient-friendly dosing strategy is preferred. We therefore explored alternative ravulizumab dosing regimens in silico based on the thorough dose-finding studies of the manufacturer. Extending the interval to 10 weeks or individually extending the interval to a mean of 12.8 weeks based on pharmacokinetic monitoring resulted in noninferior efficacy in terms of lactate dehydrogenase normalization, with drug cost savings up to 37%. We here show the potential of individualized ravulizumab dosing to improve patient-friendliness at reduced costs.
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http://dx.doi.org/10.1111/bcp.14748DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8359320PMC
August 2021

Mortality, life expectancy, and causes of death of persons with hemophilia in the Netherlands 2001-2018.

J Thromb Haemost 2021 03 18;19(3):645-653. Epub 2020 Dec 18.

Department of Clinical Epidemiology, Leiden University Medical Center, Leiden, the Netherlands.

Background: Treatment of patients with hemophilia has advanced over the past decades, but it is unknown whether this has resulted in a normal life expectancy in the Netherlands.

Objective: This observational cohort study aimed to assess all-cause and cause-specific mortality in patients with hemophilia in the Netherlands between 2001 and 2018 and to compare mortality and life expectancy with previous survival assessments from 1973 onward.

Patients/methods: All 1066 patients with hemophilia who participated in a nationwide survey in 2001 were followed until July 2018.

Results: Information on 1031 individuals (97%) was available, of whom 142 (14%) deceased during follow-up. Compared with the general Dutch male population, mortality of patients with hemophilia was still increased (standardized mortality ratio: 1.4, 95% confidence interval: 1.2-1.7). Intracranial bleeding and malignancies were the most common causes of death. Estimated median life expectancy of patients with hemophilia was 77 years, 6 years lower than the median life expectancy of the general Dutch male population (83 years). Over the past 45 years, death rates of patients with hemophilia have consistently decreased, approaching the survival experience of the general population. Over the past decades, mortality due to human immunodeficiency virus and hepatitis C virus infections has decreased, death due to intracranial hemorrhages has increased, and death due to ischemic heart disease has remained consistently low over time.

Conclusions: Survival in patients with hemophilia in the Netherlands has improved over time but is still lower than that of the general population.
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http://dx.doi.org/10.1111/jth.15182DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7986360PMC
March 2021

Bleeding severity in patients with rare bleeding disorders: real-life data from the RBiN study.

Blood Adv 2020 10;4(20):5025-5034

Department of Hematology, Radboud University Medical Center, Nijmegen, The Netherlands.

Patients with hereditary rare bleeding disorders (RBDs) present with diverse hemorrhagic symptoms. Correlation between factor activity levels and clinical bleeding severity is poor for most RBDs. Threshold factor activity levels have been previously described in relation to bleeding severity but have not yet been validated. The Rare Bleeding Disorders in the Netherlands (RBiN) study is a nationwide cross-sectional study of patients registered in all 6 Dutch Haemophilia Treatment Centers with a known RBD and who are age 1 to 99 years. Bleeding scores were determined, and laboratory and clinical data were extracted from patient files. In all, 263 patients were included, of whom 202 (77%) attended the scheduled study visit. The median International Society of Thrombosis and Haemostasis (ISTH) bleeding assessment tool (BAT) score was 9. Correlations between baseline factor activity levels and ISTH BAT scores were strong for deficiencies in factor II (FII) (r = -0.792) and FX (r = -0.838) and were moderate for deficiencies of fibrinogen (r = -0.683), FV (r = -0.623), FVII (r = -0.516), FXIII (r = -0.516), and α2-antiplasmin (r = -0.594). There was no correlation for FXI deficiency (r = -0.218). The RBD BAT identified more women (94% vs 83%) and children (100% vs 71%) with an RBD than the ISTH BAT did. Importantly, 48% of patients had more severe bleeding than predicted for their baseline factor activity level. In addition, 34% of patients were predicted to be asymptomatic, but they actually had grade 2 (31%) or 3 (3%) bleeding. Bleeding severity in patients with RBDs is more pronounced than previously anticipated. The previously determined threshold factor activity levels to ensure no (spontaneous) bleeding in patients with an RBD are inaccurate. This trial was registered at www.clinicaltrials.gov as #NCT03347591.
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http://dx.doi.org/10.1182/bloodadvances.2020002740DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7594388PMC
October 2020

Pharmacodynamic monitoring of factor VIII replacement therapy in hemophilia A: Combining thrombin and plasmin generation.

J Thromb Haemost 2020 12 21;18(12):3222-3231. Epub 2020 Oct 21.

Department of Hematology, Radboud University Medical Centre, Nijmegen, the Netherlands.

Background: Clinical severity of hemophilia A (HA) varies, possibly due to interplay of many factors in the hemostatic pathway. Pharmacokinetic monitoring of factor VIII (FVIII) replacement therapy in HA patients consists of measuring FVIII activity levels and subsequent dose adjustment. The Nijmegen Hemostasis Assay (NHA) measures thrombin generation (TG) and plasmin generation (PG).

Objective: To determine differences in TG and PG between HA patients before and during a pharmacokinetic study and identify best parameters to develop a pharmacodynamic model.

Methods: Twenty-five HA patients (baseline FVIII < 1-9 IU/dL) underwent a pharmacokinetic study with a single dose of 25-50 IU/kg standard half-life FVIII concentrate. At baseline and after administration of FVIII TG and PG parameters were measured with the NHA.

Results: FVIII activity level increased from median 1.0 IU/dL (interquartile range < 1.0-6.0) to 71 IU/dL (62-82) 15 minutes after administration and decreased to 15 IU/dL (10-26) at 24 hours. TG was enhanced simultaneously, with thrombin peak height (TPH) increasing from 22nM (15-35) to 222nM (159-255), and thrombin potential (TP) from 404nM/min (undetectable-876) to 1834nM/min (1546-2353). Twenty-four hours after infusion, TG parameters remained high (TPH 73nM [58.5-126.3]; TP 1394nM/min [1066-1677]) compared to FVIII activity level. PG showed hyperfibrinolysis in severe HA patients compared to mild patients and controls, which normalized after FVIII supplementation.

Conclusion: HA patients showed clear differences in baseline TG and PG despite having comparable FVIII activity levels. These results reveal a discrepancy between FVIII activity level and TG, in which the latter may be a better parameter to monitor individualized treatment in HA patients.
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http://dx.doi.org/10.1111/jth.15106DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7756259PMC
December 2020

Effect of emicizumab on thrombin generation: A case report of breakthrough bleeding during emicizumab treatment.

Haemophilia 2020 Nov 28;26(6):e327-e330. Epub 2020 Jun 28.

Department of Haematology, Radboud University Medical Centre, Nijmegen, The Netherlands.

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http://dx.doi.org/10.1111/hae.14085DOI Listing
November 2020

Pregnancy outcome in afibrinogenemia: Are we giving enough fibrinogen concentrate? A case series.

Res Pract Thromb Haemost 2020 Feb 22;4(2):343-346. Epub 2020 Jan 22.

Department of Hematology Radboud Universisty Medical Center Nijmegen The Netherlands.

Congenital afibrinogenemia is a rare autosomal recessive disorder associated with an increased risk of hemorrhage, thrombosis, and obstetric complications. This case series of 4 pregnancies in 2 related patients seeks to address the key clinical question of the necessary doses of fibrinogen concentrate during pregnancy and puerperium. One pregnancy without the prophylactic use of fibrinogen concentrate resulted in spontaneous abortion. The second pregnancy was complicated by a subchorionic hematoma despite the prophylactic administration of fibrinogen concentrate to maintain the plasma trough levels at ≥0.6 g/L. Labor was complicated by postpartum hemorrhage with a blood loss volume of 1480 cc. Two weeks later, the patient presented with postpartum thrombosis. The other 2 pregnancies were uncomplicated with fibrinogen trough levels ≥1.0 g/L during pregnancy and ≥1.5 g/L during labor. These cases illustrate that during pregnancy, patients may benefit from fibrinogen trough levels ≥1.0 g/L. In addition, the increased risk of postpartum thrombosis with prolonged fibrinogen supplementation warrants personalized postpartum advice that is guided by postpartum blood loss.
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http://dx.doi.org/10.1002/rth2.12300DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7040545PMC
February 2020

Diagnostic work up of patients with increased bleeding tendency.

Haemophilia 2020 Mar 30;26(2):269-277. Epub 2019 Dec 30.

Department of Haematology, Radboud University Medical Center, Nijmegen, The Netherlands.

Introduction: The diagnostic trajectory of patients with increased bleeding tendency can be very costly and time-consuming. In addition, previous studies have shown that half of these patients remain without final diagnosis despite all efforts.

Aim: This study aimed to improve insight into the current diagnostic process of these patients.

Methods: A total of 117 adult patients, referred to an academic hospital because of being suspected to have an increased bleeding tendency, were included. Different parameters were compared between patients receiving final diagnosis, patients without final diagnosis but a high Tosetto bleeding assessment tool (BAT) score (classified as bleeding of unknown cause, or BUC) and a control group consisting of patients without final diagnosis and a low BAT score.

Results: The BAT score was significantly higher in patients in the BUC group as compared to patients reaching final diagnosis (8.1 vs 4.9). Interestingly, the two subcategories most prevalently increased were surgery and post-partum haemorrhage-associated bleeding (surgery: 2.1 vs 1.1; post-partum haemorrhage: 0.7 vs 0.0). Laboratory screening results were more often abnormal in patients reaching final diagnosis compared to patients remaining without diagnosis and a high BAT score (n = 32 (78%) vs n = 14 (46%), 95% CI 1.5-12), especially concerning the PFA (=27 (66%) vs n = 10 (33%), 95% CI 1.4-10) and von Willebrand factor activity levels (n = 11 (27%) vs n = 1 (3%), 95% CI 1.3-91).

Conclusion: Isolated high bleeding score on surgical or post-partum bleeding correlates with a lower chance of receiving final diagnosis. Withholding extensive haemostatic testing should be considered. Better screening and confirmative haemostatic assays are still needed.
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http://dx.doi.org/10.1111/hae.13922DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7155060PMC
March 2020

Thrombin and plasmin generation in patients with plasminogen or plasminogen activator inhibitor type 1 deficiency.

Haemophilia 2019 Nov 30;25(6):1073-1082. Epub 2019 Aug 30.

Haemophilia Treatment Center, Nijmegen, Eindhoven, Maastricht, The Netherlands.

Introduction: Deficiencies of plasminogen and plasminogen activator inhibitor type 1 (PAI-1) are rare disorders of fibrinolysis. Current laboratory assays for analysis of activity of plasminogen and PAI-1 do not provide an accurate correlation with clinical phenotype.

Methods: The Nijmegen Hemostasis Assay (NHA) was used to simultaneously measure thrombin and plasmin generation in 5 patients with plasminogen deficiency (PLGD) and 10 patients with complete PAI-1 deficiency. Parameters analysed included: lag time ratio, thrombin peak time ratio, thrombin peak height, thrombin potential (AUC), fibrin lysis time, plasmin peak height and plasmin potential. Parameters were expressed as a percentage compared to a reference value of 53 healthy normal controls.

Results: Patients with PLGD demonstrated a short lag time and thrombin peak time, with normal thrombin peak height but an increased AUC. Plasmin generation was able to be detected in only one (23% plasminogen activity) of the five PLGD patients. All ten PAI-1 deficient patients demonstrated a short lag and thrombin peak time, low thrombin peak height with normal AUC. Plasmin generation revealed an increased plasmin peak and plasmin potential; interestingly, there was a large variation between individual patients despite all patients having the same homozygous defect.

Conclusion: Patients with either PLGD or PAI-1 deficiency show distinct abnormalities in plasmin and thrombin generation in the NHA. The differences observed in the propagation phase of thrombin generation may be explained by plasmin generation. These results suggest that disorders of fibrinolysis also influence coagulation and a global assay measuring both activities may better correlate with clinical outcome.
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http://dx.doi.org/10.1111/hae.13842DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6899449PMC
November 2019

Pharmacology, Pharmacokinetics and Pharmacodynamics of Eculizumab, and Possibilities for an Individualized Approach to Eculizumab.

Clin Pharmacokinet 2019 07;58(7):859-874

Department of Pharmacy, Radboud University Medical Center, Nijmegen, The Netherlands.

Eculizumab is the first drug approved for the treatment of complement-mediated diseases, and current dosage schedules result in large interindividual drug concentrations. This review provides insight into the pharmacokinetic and pharmacodynamic properties of eculizumab, both for reported on-label (paroxysmal nocturnal hemoglobinuria, atypical hemolytic uremic syndrome, generalized myasthenia gravis) and off-label (hematopoietic stem cell transplantation-associated thrombotic microangiopathy) indications. Furthermore, we discuss the potential of therapeutic drug monitoring to individualize treatment and reduce costs.
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http://dx.doi.org/10.1007/s40262-019-00742-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6584251PMC
July 2019

Iron handling by the human kidney: glomerular filtration and tubular reabsorption both contribute to urinary iron excretion.

Am J Physiol Renal Physiol 2019 03 9;316(3):F606-F614. Epub 2019 Jan 9.

Department of Laboratory Medicine, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center , Nijmegen , The Netherlands.

In physiological conditions, circulating iron can be filtered by the glomerulus and is almost completely reabsorbed by the tubular epithelium to prevent urinary iron wasting. Increased urinary iron concentrations have been associated with renal injury. However, it is not clear whether increased urinary iron concentrations in patients are the result of increased glomerular iron filtration and/or insufficient tubular iron reabsorption and if these processes contribute to renal injury. We measured plasma and urine iron parameters and urinary tubular injury markers in healthy human subjects ( n = 20), patients with systemic iron overload ( n = 20), and patients with renal tubular dysfunction ( n = 18). Urinary iron excretion parameters were increased in both patients with systemic iron overload and tubular dysfunction, whereas plasma iron parameters were only increased in patients with systemic iron overload. In patients with systemic iron overload, increased urinary iron levels were associated with elevated circulating iron, as indicated by transferrin saturation (TSAT), and increased body iron, as suggested by plasma ferritin concentrations. In patients with tubular dysfunction, enhanced urinary iron and transferrin excretion were associated with distal tubular injury as indicated by increased urinary glutathione S-transferase pi 1-1 (GSTP1-1) excretion. In systemic iron overload, elevated urinary iron and transferrin levels were associated with increased injury to proximal tubules, indicated by increased urinary kidney injury marker 1 (KIM-1) excretion. Our explorative study demonstrates that both glomerular filtration of elevated plasma iron levels and insufficient tubular iron reabsorption could increase urinary iron excretion and cause renal injury.
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http://dx.doi.org/10.1152/ajprenal.00425.2018DOI Listing
March 2019

Whole exome sequencing in the diagnostic workup of patients with a bleeding diathesis.

Haemophilia 2019 Jan 15;25(1):127-135. Epub 2018 Nov 15.

Department of Hematology, Radboud University Medical Center, Nijmegen, The Netherlands.

Introduction: Bleeding assessment tools and laboratory phenotyping often remain inconclusive in patients with a haemorrhagic diathesis.

Aim: To describe the phenotype and genetic profile of patients with a bleeding tendency.

Methods: Whole exome sequencing (WES) was incorporated in the routine diagnostic pathway of patients with thrombocytopenia (n = 17), platelet function disorders (n = 19) and an unexplained bleeding tendency (n = 51). The analysis of a panel of 126 OMIM (Online Mendelian Inheritance in Man) genes involved in thrombosis and haemostasis was conducted, and if negative, further exome-wide analysis was performed if informed consent given.

Results: Eighteen variants were detected in 15 patients from a total of 87 patients (17%). Causative variants were observed in MYH9 (two cases), SLFN14, P2RY12 and GP9. In addition, one case was considered solved due to combined carriership of F7 and F13A1 variants and one with combined carriership of F2, F8 and VWF, all variants related to secondary haemostasis protein aberrations. Two variants of uncertain significance (VUS) were found in two primary haemostasis genes: GFI1B and VWF. Eight patients were carriers of autosomal recessive disorders. Exome-wide analysis was performed in 54 cases and identified three variants in candidate genes.

Conclusion: Based on our findings, we conclude that performing WES at the end of the diagnostic trajectory can be of additive value to explain the complete bleeding phenotype in patients without a definite diagnosis after conventional laboratory tests. Discovery of combinations of (novel) genes that predispose to bleeding will increase the diagnostic yield in patients with an unexplained bleeding diathesis.
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http://dx.doi.org/10.1111/hae.13638DOI Listing
January 2019

Recurrent extramedullary plasmacytoma in asymptomatic multiple myeloma: a case report.

J Med Case Rep 2015 Feb 19;9:37. Epub 2015 Feb 19.

Department of Internal Medicine, Máxima Medical Centre, De Run 4600, 5504 DB, Veldhoven, The Netherlands.

Introduction: The gross majority of extramedullary plasmacytomas arise in the lymphatic tissue of the upper respiratory tract. On average, one third of patients with a solid plasmacytoma will develop multiple myeloma, resulting in a worse clinical outcome. We describe a case of rapid recurrent extramedullary plasmacytomas in the background of an asymptomatic multiple myeloma.

Case Presentation: A 71-year-old, white Caucasian woman presented with three extramedullary plasmacytomas occurring within a short time period. The third plasmacytoma was accompanied by progressive cervical pain and swallow dysfunction. Additional immunostaining test results were negative for CD56 and showed high MIB-1 expression in the extramedullary plasmacytoma and low MIB-1 expression in the bone marrow. A conventional swallow X-ray did not show any obstruction, however a magnetic resonance imaging scan of her cervical backbone revealed an extramedullary plasmacytoma, threatening her spinal cord. A short course of radiation therapy alleviated her pain and during almost a two-year follow-up period, the multiple myeloma remained asymptomatic, despite the rise in immunoglobulin A lambda levels. After the appearance of the third plasmacytoma, systemic chemotherapy was started to prevent the development of a fourth plasmacytoma, despite the asymptomatic character of the multiple myeloma.

Conclusions: In this case report we describe the rapid appearance of extramedullary plasmacytomas in the background of an asymptomatic multiple myeloma. An immunohistochemical analysis was negative for CD56 and showed high MIB-1 expression in the extramedullary plasmacytoma and low MIB-1 expression in the bone marrow, contributing to the potential underlying pathophysiology of the recurrent extramedullary plasmacytomas and their genetic changes. Systemic chemotherapy was started and no fourth extramedullary plasmacytoma has developed since.
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http://dx.doi.org/10.1186/s13256-014-0506-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4343069PMC
February 2015

Key role of glycoprotein Ib/V/IX and von Willebrand factor in platelet activation-dependent fibrin formation at low shear flow.

Blood 2011 Jan 29;117(2):651-60. Epub 2010 Oct 29.

Department of Biochemistry, Maastricht University MedicalCentre, Maastricht, The Netherlands.

A microscopic method was developed to study the role of platelets in fibrin formation. Perfusion of adhered platelets with plasma under coagulating conditions at a low shear rate (250(-1)) resulted in the assembly of a star-like fibrin network at the platelet surface. The focal fibrin formation on platelets was preceded by rises in cytosolic Ca(2+), morphologic changes, and phosphatidylserine exposure. Fibrin formation was slightly affected by α(IIb)β(3) blockage, but it was greatly delayed and reduced by the following: inhibition of thrombin or platelet activation; interference in the binding of von Willebrand factor (VWF) to glycoprotein Ib/V/IX (GpIb-V-IX); plasma or blood from patients with type 1 von Willebrand disease; and plasma from mice deficient in VWF or the extracellular domain of GpIbα. In this process, the GpIb-binding A1 domain of VWF was similarly effective as full-length VWF. Prestimulation of platelets enhanced the formation of fibrin, which was abrogated by blockage of phosphatidylserine. Together, these results show that, in the presence of thrombin and low shear flow, VWF-induced activation of GpIb-V-IX triggers platelet procoagulant activity and anchorage of a star-like fibrin network. This process can be relevant in hemostasis and the manifestation of von Willebrand disease.
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http://dx.doi.org/10.1182/blood-2010-01-262683DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3320850PMC
January 2011

Spatial distribution of factor Xa, thrombin, and fibrin(ogen) on thrombi at venous shear.

PLoS One 2010 Apr 29;5(4):e10415. Epub 2010 Apr 29.

Department of Biochemistry, CARIM, Maastricht University, Maastricht, The Netherlands.

Background: The generation of thrombin is a critical process in the formation of venous thrombi. In isolated plasma under static conditions, phosphatidylserine (PS)-exposing platelets support coagulation factor activation and thrombin generation; however, their role in supporting coagulation factor binding under shear conditions remains unclear. We sought to determine where activated factor X (FXa), (pro)thrombin, and fibrin(ogen) are localized in thrombi formed under venous shear.

Methodology/principal Findings: Fluorescence microscopy was used to study the accumulation of platelets, FXa, (pro)thrombin, and fibrin(ogen) in thrombi formed in vitro and in vivo. Co-perfusion of human blood with tissue factor resulted in formation of visible fibrin at low, but not at high shear rate. At low shear, platelets demonstrated increased Ca(2+) signaling and PS exposure, and supported binding of FXa and prothrombin. However, once cleaved, (pro)thrombin was observed on fibrin fibers, covering the whole thrombus. In vivo, wild-type mice were injected with fluorescently labeled coagulation factors and venous thrombus formation was monitored in mesenteric veins treated with FeCl(3). Thrombi formed in vivo consisted of platelet aggregates, focal spots of platelets binding FXa, and large areas binding (pro)thrombin and fibrin(ogen).

Conclusions/significance: FXa bound in a punctate manner to thrombi under shear, while thrombin and fibrin(ogen) distributed ubiquitously over platelet-fibrin thrombi. During thrombus formation under venous shear, thrombin may relocate from focal sites of formation (on FXa-binding platelets) to dispersed sites of action (on fibrin fibers).
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0010415PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2861630PMC
April 2010

Correction of coagulation in dilutional coagulopathy: use of kinetic and capacitive coagulation assays to improve hemostasis.

Transfus Med Rev 2010 Jan;24(1):44-52

Department of Biochemistry, CARIM, Maastricht University Medical Centre, Maastricht, The Netherlands.

The management of dilutional coagulopathy due to fluid infusion and massive blood loss is a topic that deserves a biochemical approach. In this review article, we provide an overview of current guidelines and recommendations on diagnosis and on management of transfusion in acquired coagulopathy. We discuss the biochemical differences between kinetic clotting assays (clotting times) and new capacitive coagulation measurements that provide time-dependent information on thrombin generation and fibrin clot formation. The available evidence suggests that a combination of assay types is required for evaluating new transfusion protocols aimed to optimize hemostasis and stop bleeding. Although there is current consensus on the application of fresh frozen plasma to revert coagulopathy, factor concentrates may appear to be useful in the future.
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http://dx.doi.org/10.1016/j.tmrv.2009.09.004DOI Listing
January 2010

Effects of plasma dilution on tissue-factor-induced thrombin generation and thromboelastography: partly compensating role of platelets.

Transfusion 2008 Nov 23;48(11):2384-94. Epub 2008 Jul 23.

Department of Biochemistry, Maastricht University and University Hospital, Maastricht, The Netherlands.

Background: Bleeding upon major surgery or severe trauma is treated by transfusion with crystalloids, colloids, or plasma. This treatment, however, can lead to dilutional coagulopathy and impaired hemostasis. We investigated the suitability of two integrative coagulation tests to measure the hemostatic activity of diluted plasma.

Study Design And Methods: Plasma from healthy donors was diluted in vitro with saline or colloid (venofundin or gelofusin). Coagulant activity in response to tissue factor was monitored by calibrated automated thrombin (CAT) generation and rotational thromboelastography (TEG), detecting formation of elastic fibrin clots. Plasma from patients receiving fluid infusion during coronary artery bypass grafting (CABG) was analyzed with the same assays.

Results: Optimal activity of CAT and TEG assays required the presence of 10 pmol per L tissue factor and 4 micromol per L phospholipid vesicles or 100 x 10(9) platelets (PLTs) per L. Strikingly, thrombin generation and clot formation became impaired at a higher extent of dilution with PLTs present (< or =40% plasma) than with phospholipid vesicles present (< or =60% plasma). Colloids aggravated the dilution effect on clot formation, but FFP antagonized the dilution effect on thrombin and clot formation. In contrast, fibrinogen and Factor (F)XIII only restored the impaired clot formation. In plasma samples from patients undergoing CABG, CAT and TEG assay variables were altered to an extent corresponding with the volume of fluid infusion.

Conclusion: Thrombin generation and clot formation are reduced at a plasma dilution of more than 40 percent. In either process, PLTs can partly compensate for the dilution effect. In vitro dilution with colloids impaired fibrin clot elasticity compared to saline.
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http://dx.doi.org/10.1111/j.1537-2995.2008.01872.xDOI Listing
November 2008

Increased thrombin generation and fibrinogen level after therapeutic plasma transfusion: relation to bleeding.

Thromb Haemost 2008 Jan;99(1):64-70

Department of Biochemistry (CARIM), Maastricht University, Maastricht, The Netherlands.

In a clinical setting, fresh frozen plasma (FFP) is transfused to diluted patients with complicated surgery or trauma, as guided by prolonged conventional coagulation times or low fibrinogen levels. However, the limited sensitivity of these coagulation tests may restrict their use in measuring the effect of transfusion and hence predicting the risk of perioperative bleeding. We used the more sensitive, calibrated automated thrombogram (CAT) method to evaluate the result of therapeutic FFP transfusion to 51 patients with dilutional coagulopathy. Thrombin generation was measured in pre- and post-transfusion plasma samples in the presence of either platelets or phospholipids. For all patients, the transfusion led to higher plasma coagulation factor levels, a shortened activated partial thromboplastin time, and a significant increase in thrombin generation (peak height and endogenous thrombin potential). Interestingly, thrombin generation parameters and fibrinogen levels were higher in post-transfusion plasmas from patients who stopped bleeding (n = 32) than for patients with ongoing bleeding (n = 19). Plasmas from 15 of the 19 patients with ongoing bleeding were markedly low in either thrombin generation or fibrinogen level. We conclude that the thrombin generation method detects improved haemostatic activity after plasma transfusion. Furthermore, the data suggest that thrombin generation and fibrinogen are independent determinants of the risk of perioperative bleeding in this patient group.
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http://dx.doi.org/10.1160/TH07-07-0438DOI Listing
January 2008
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