Joost T. M. de Wolf

An effective treatment of severe intractable bleeding after valve repair by one single dose of activated recombinant factor VII.

IMPLICATIONS The successful treatment with recombinant factor VIIa of a patient experiencing intractable bleeding after cardiac surgery is described.

Platelet kinetic studies in patients with idiopathic thrombocytopenic purpura

PURPOSE To determine the value in diagnosis and treatment of mean platelet life, platelet production, and major sites of platelet destruction in patients with idiopathic thrombocytopenic purpura (ITP). PATIENTS AND METHODS Sternal or posterior superior iliac spine bone marrow aspiration was performed in 141 patients. Platelet kinetic studies with Indium-111 tropolonate labeled autologous platelets were utilized to determine platelet production. RESULTS Two subgroups of patients could be defined. The first group (n = 81, 58%) had normal or increased platelet production and increased peripheral platelet destruction. These patients fulfilled the conventional criteria for ITP, including reduced platelet survival time (mean +/- SD, 1.6 +/- 1.4 days). Forty-eight (59%) of these patients had increased splenic sequestration and 30 (88%) of the 34 patients who underwent splenectomy had a complete or partial remission. The second group (n = 60, 42%) had decreased platelet production, with significantly greater platelet survival times (3.6 +/- 2 days, P <0.0001). In this group, the proportion of patients with complete or partial response to splenectomy (62%) was somewhat lower (P = 0.09). These patients mainly had ineffective platelet production in the bone marrow. CONCLUSIONS Platelet kinetic studies suggest that ITP is a heterogeneous disease that comprises two subgroups. Further studies are needed to validate these findings and to determine their effect on the choice and outcome of therapy.

In Normal Controls, Both Age and Gender Affect Coagulability as Measured by Thrombelastography

BACKGROUND:Our objective was to analyze the effects of age, gender, and the use of oral contraceptives (OCs) on coagulation using thrombelastography (TEG®), a single test to analyze both plasma coagulation factors and cellular elements in whole blood. METHODS:TEG® variables were measured in native whole blood and in recalcified citrated blood from 120 healthy adults (60 men and 60 women) with various ages and in an additional 29 healthy women using OCs. RESULTS:We observed hypercoagulability in women compared with men and in women using OCs compared with age-matched nonusers. Moreover, we found hypercoagulability with aging. Using the method of Bland and Altman (Lancet 1986;1:307–10), we demonstrated no correlation between TEG® measurements in native and recalcified citrated blood. CONCLUSIONS:Aging, female gender, use of OCs, and low-normal hematocrit levels have significant procoagulant effects. TEG® measurements in native and recalcified citrated blood are not interchangeable, as indicated by differences between the 2 measurements ranging from 20%in maximal amplitude to 246% in clotting time. Furthermore, the limits of agreement strongly exceeded clinical acceptability to conclude interchangeability.

Mitochondrial disruption and limited apoptosis of erythroblasts are associated with high risk myelodysplasia. An ultrastructural analysis

AIMS To investigate the ultrastructural characteristics of erythroblasts in myelodysplasia (MDS) which might be of additional importance in understanding its pathogenesis. METHODS AND RESULTS 22 patients were classified according to FAB (French-American-British classification), IPSS (international prognostic score system), cytogenetic risk factors and transfusion dependency. Using electron microscopy, in 77% of the cases, nuclear abnormalities consisting of disrupted membranes and cystic/dilated perinuclear spaces were noted. In a limited number of patients (n=7), a low percentage of apoptosis in the erythroid lineage (mean 3.1+/-1.6%; median 3%: range 1-6) (normal controls: <0.5%) could be noted, primarily in mature erythroblasts and significantly associated with spongiform nuclear features. In all patients extensive cytoplasmic vacuolization and myelin figures in erythroblasts were demonstrated. In 55% of the cases, enlarged and abnormal mitochondria were observed, significantly associated with iron-accumulation. A significant inverse relation existed between the absence of apoptosis and more advanced, or high risk disease and cytogenetic risk factors. Mitochondrial abnormalities were significantly correlated with high risk disease as well with an increase in transfusion dependency. CONCLUSIONS These data indicate that in MDS apoptosis may play a role in early stages of disease. The overall prominent defects in mitochondria might be an additional defect that is involved in ineffective erythropoiesis.

Combined thalidomide and cyclophosphamide treatment for refractory or relapsed multiple myeloma patients : a prospective phase II study

Thalidomide is an effective agent for patients with refractory multiple myeloma (MM) with a response rate of 30–40% at doses of 200–800 mg but with considerable side effects. We questioned whether lower doses of thalidomide in combination with a daily dose of cyclophosphamide might be an effective regimen with fewer side effects. We included 38 patients with relapsed or refractory MM. The median doses of thalidomide and cyclophosphamide were 100 and 95 mg/day, respectively. Side effects were observed in all patients, with neurotoxicity as the most troublesome. With a median follow-up of 14 months 84% of the patients responded, including 64% partial responses. The median time of progression-free survival was 30 months and the median overall survival time was 20 months. In conclusion, the results demonstrate that the combination of low-dose thalidomide with a daily dose of cyclophosphamide is an effective regimen with a high overall response rate and manageable side effects.

Efficacy of single-agent lenalidomide in patients with JAK2 (V617F) mutated refractory anemia with ring sideroblasts and thrombocytosis

Patients with refractory anemia with ring sideroblasts and thrombocytosis (RARS-T) are difficult to treat because the cytoreductive treatment might be beneficial for the thrombocytosis component but harmful for the RARS component. As lenalidomide has shown to be efficacious in both myelodysplastic syndromes and myeloproliferative neoplasms, we have treated 2 RARS-T patients, who were transfusion dependent, with lenalidomide. We report the results of lenalidomide treatment in these patients and show that lenalidomide has clinical activity in this rare disorder. Both patients became transfusion independent, and 1 of the patients attained indeed a complete molecular remission.

The in vitro effects of cytokines on expansion and migration of megakaryocyte progenitors

Increasing the number of megakaryocyte progenitors in stem cell transplants by ex vivo expansion culture may be an approach to accelerate platelet recovery in patients undergoing high‐dose chemotherapy. We evaluated the effect of three different cytokine combinations on expansion, with special emphasis on the type of colony formation and migration of megakaryocytic cells. The number of clonogenic megakaryocyte progenitors (colony‐forming units–megakaryocyte; CFU‐Mk) with high‐ (> 20 cells/colony) and low‐proliferative capacity (5–20 cells/colony) and the number of megakaryocytic (CD61+) cells were significantly increased by including interleukin 3 (IL‐3) or IL‐3 + IL‐6 + IL‐11 + Flt3‐ligand to cultures containing megakaryocyte growth and development factor (MGDF) plus stem cell factor (SCF). No difference in the maturation of megakaryocytes from all three cytokine combinations to platelets were observed, as demonstrated by electron microscopy. In chemotaxis experiments, the migration towards stromal cell‐derived factor 1 (SDF‐1) was shown to be reduced for CD61+ cells and megakaryocyte progenitors cultured in other cytokines besides MGDF + SCF. The reduced migration was related to a lower expression of CXCR4, the receptor for SDF‐1, on megakaryocytes from the proliferating cultures. These in vitro results demonstrate that expansion in IL‐3 and other cytokines besides MGDF + SCF significantly impair the capacity of megakaryocytic cells to migrate.

Thrombocytopenia affects plasmatic coagulation as measured by thrombelastography

Thrombelastography (TEG) is used as a point-of-care test of hemostasis. Different components of the test tracing are considered to reflect various parts of the hemostatic system and to distinguish low platelet count, platelet dysfunction or both from lack of plasmatic coagulation factors. To analyze the influence of one single element of the coagulation system, namely the platelet count, we used TEG serially in patients with well documented transient thrombocytopenia. A total of 189 TEG analyses were performed from 16 patients with a hematological malignancy in remission, receiving consolidation courses of chemotherapy. TEG outcomes using unmanipulated and citrated blood samples at a median of 11 times (range 1–17) in the same patients during the decrease of platelet count in response to chemotherapy were compared with outcomes in 120 healthy adults from various age categories. We found a correlation (r = 0.7, P < 0.001) between TEG clot strength (maximum amplitude) and platelet count. Moreover, platelet count was correlated respectively with the initial rate of clot formation (reaction time and clotting time), the rate of clot growth (alpha angle), and also with maximum thrombus generation, time to maximum thrombus generation and total thrombus generation. We conclude that platelet count not only affects the strength of clot formation, as was expected, but also all other phases of plasmatic coagulation. Citration of the blood sample, aiming at easy storage of the material, masked some of the important biological parameters of coagulation.

Effects of red blood cells on hemostasis.

BACKGROUND: Currently there is no sensitive laboratory test to establish the influence of red blood cells (RBCs) on hemostasis. As thromboelastography (TEG) measures hemostasis in whole blood, taking into account the interactions of all cellular elements, we used this instrument to investigate the role that RBCs play in hemostasis.

Quantifying the reduction in immunoglobulin use over time in patients with chronic immune thrombocytopenic purpura receiving romiplostim (AMG 531)

Patients with Immune thrombocytopenic purpura (ITP) often require immunoglobulin (Ig) therapy with intravenous 19 (IVIG) or anti-D to prevent or treat the serious bleeding events. Because the thrombopoietin (TPO) mimetic romiplostim (AMG 531; Nplate) elevates platelet counts in patients with chronic ITP, we quantified to what extent it reduced the incidence of Ig rescue therapy in two randomized (vs. placebo) trials of romiplostim for chronic ITP. Our analysis shows that significantly fewer romiplostim patients than placebo patients required Ig therapy over the course of 24 weeks (1-6% vs. 19-37%, respectively; P <0.05 for each 4-week interval), and romiplostim-treated patients were 5.31-fold less likely to receive Ig therapy (P <0.001).