Platelet degranulation and bleeding phenotype in a large cohort of Von Willebrand disease patients

Von Willebrand disease (VWD) is a bleeding disorder caused by quantitative (type 1 or 3) or qualitative (type 2A/2B/2M/2N) defects of circulating von Willebrand factor (VWF). Circulating VWF levels not always fully explain bleeding phenotypes, suggesting a role for alternative factors, like platelets. Here, we investigated platelet factor 4 (PF4) in a large cohort of patients with VWD. PF4 levels were lower in type 2B and current bleeding phenotype was significantly associated with higher PF4 levels, particularly in type 1 VWD. Based on our findings we speculate that platelet degranulation and cargo release may play a role across VWD subtypes.

Retrospective evaluation of bleeding tendency and simultaneous thrombin and plasmin generation in patients with rare bleeding disorders

Rare bleeding disorders (RBDs) are a heterogeneous group of diseases with varying bleeding tendency, only partially explained by their laboratory phenotype. We analysed the separate groups of RBD abnormalities, and we investigated retrospectively whether the novel haemostasis assay (NHA) was able to differentiate between bleeding tendency. We have performed simultaneous thrombin generation (TG) and plasmin generation (PG) measurements in 41 patients affected with deficiencies in prothrombin, factor (F) V, FVII, FX, FXIII and fibrinogen. Parameters of the NHA were classified based on (major or minor) bleeding tendency. Patients with deficiencies in coagulation propagation (FII, FV and FX) and major type of bleedings had diminished TG (expressed as AUC) below 20% of control. FVII deficient patients only had prolonged thrombin lag-time ratio of 1.6 ± 0.2 (P < 0.05) and normal AUC (92-125%). Afibrinogenemic patients demonstrated PG of 2-29% of normal and appeared to correlate with the type of mutation. Thrombin peak-height (57 ± 16%) was reduced (not significant) in these patients and AUC was comparable to the reference (102 ± 27%). FXIII-deficient plasmas resulted in a reduced thrombin peak-height of 59 ± 13% (P < 0.05) and normal AUC (90 ± 14%). Thrombin peak-height (P < 0.01) and plasmin potential (P < 0.05) were lower in the major bleeders compared with the minor bleeders. These results provided distinct TG and PG curves for each individual abnormality and differentiation of bleeding tendency was observed for thrombin and PG parameters. Prospective studies are warranted to confirm these retrospective results.

Health-related quality of life after completion of successful treatment for childhood cancer

BACKGROUND

Previous studies have assessed health-related quality of life (HRQOL) during several treatment stages in children with cancer, but there is limited knowledge about HRQOL shortly after completing therapy. This study determined HRQOL of children with cancer shortly after the end of successful treatment compared with normative values.

PROCEDURE

Several age-specific HRQOL questionnaires were administered: the ITQOL (generic, proxy-report, 0-4 years), CHQ PF 50 (generic, proxy-report, 5-7 years), Kidscreen (generic, self-report, 8-18 years) and Disabkids (chronic generic, self-report, 8-18 years).

RESULTS

Children with cancer (N = 191, mean age 9.25, SD 5.06, 47.1% female) participated. Physical well-being was affected for all ages. Compared to normative values 0- to 7-year-olds were rated significantly lower on the majority of the scales. In addition, 12- to 18-year-olds had significantly better HRQOL than the norm on social scales. Compared to chronically ill norms, 8- to 18-year-olds demonstrated no differences, except for 12- to 18-year-olds who experienced significantly more physical limitations. Additionally, we found that HRQOL of parents of 0- to 7-year-olds was poorer than the norm.

CONCLUSION

HRQOL in children with cancer and their parents can be impaired compared with the norm. Therefore, HRQOL should be monitored in clinical practice to make paediatric oncologists aware of these problems. For young children, we recommend checking whether certain HRQOL problems can be explained by parental worries. For older children and adolescents, paediatric oncologists need to consider social desirability and the child's adaptive style.

Hemophilia a and spinal epidural hematoma in children

Hemophilia A is an X-linked bleeding disorder, caused by deficient or defective blood coagulation factor VIII. The most characteristic symptoms of the severe forms of hemophilia A are joint and muscle bleeds. Intracranial hemorrhage occurs only in 3-10% of the patients. Spinal epidural hematomas are rarely seen. We describe a 13-month-old boy with hemophilia A who was admitted to the hospital because of irritability and unspecified pain for the past two days. There was no history of evident trauma, no fever. Physical investigation showed no skin lesions or hematomas and no obvious cause for the pain. Neurological examination showed a dysphoric toddler, mainly in the fetal position. No neurological abnormalities were found except for a miosis of the right pupil due to a suspected Horner syndrome. Magnetic resonance imaging of the spine showed an extensive epidural hematoma. The boy was successfully treated with intensive replacement therapy during three weeks and did not require surgical intervention. There was a rapid and complete clinical resolution. In conclusion, rare hematomas should be considered and searched for in children with bleeding disorders and not well understood complaints. Early diagnosis is important for the neurological outcome.

Detection of incorporated iododeoxyuridine in colonies by immunoperoxidase staining: a novel method to measure the proportion of cycling colony-forming cells

In vitro suicide by tritiated thymidine (3H-TdR), hydroxyurea (HU), or cytosine arabinoside (Ara-C) is assumed to reflect the proportion of colony-forming cells in S-phase at the time of exposure. However, these techniques are not always accurate. Nonradioactive iododeoxyuridine (IdUrd) is incorporated into DNA during S-phase and can be detected by monoclonal antibodies. In the present study, a new IdUrd application was developed to investigate the kinetics of hematopoietic progenitor cells. After incubation with IdUrd, colony-forming cells were cultured in semisolid assay. An immunoperoxidase staining protocol was developed to detect IdUrd in cells of colonies in agar. Colony-forming cells in S-phase during the IdUrd exposure were postulated to give rise to IdUrd+ colonies, whereas non-S-phase cells would generate IdUrd- colonies. Toxicity, sensitivity, and IdUrd inactivation studies indicated that progenitor cells could safely be pulse-labeled for 2 hours with 40 microM IdUrd, whereas prolonged labeling with 1 microM IdUrd was at least feasible for 5 days. Molt-4 cells and normal bone marrow cells were used to compare IdUrd pulse-labeling with 3H-TdR suicide. Part of the Molt-4 cells were enriched for G1- and S-phase cells by counterflow centrifugation. The bone marrow cells were either unstimulated or stimulated with growth factors. As a result, the accuracy of both techniques could be tested in populations with different quantities of S-phase cells. Wide confidence intervals of the suicide technique contrasted with the small confidence intervals obtained with IdUrd pulse-labeling. For instance, the fraction of Molt-4 cells with 27.8% S-phase cells contained 17.7% (confidence interval -8.2 to 43.6%) clonogenic cells in S-phase when determined with 3H-TdR suicide. Of this fraction, the percentage of clonogenic cells in S-phase was 30.6% with a confidence interval of 25.5 to 36.2% when determined with IdUrd pulse-labeling. In our hands, the IdUrd pulse-labeling was more accurate than the 3H-TdR suicide technique. Thus far, kinetic studies of progenitors have been limited to the determination of the fraction of S-phase cells by suicide techniques. By prolonged IdUrd labeling, it is now possible to determine the proliferating fraction of progenitor cells.

Plasma and cellular pharmacokinetics of m-AMSA related to in vitro toxicity towards normal and leukemic clonogenic bone marrow cells (CFU-GM, CFU-L)

Plasma and cellular pharmacokinetics of m-AMSA were investigated in 5 patients with acute leukemia, using HPLC. The pharmacokinetic data served as a guideline for in vitro toxicity tests on clonogenic bone marrow cells. m-AMSA was administered as a 3-hour intravenous infusion of 100 mg/m2. Median plasma and nucleated blood cell peak concentrations were 1.25 and 6.36 micrograms/ml followed by biphasic elimination with a median T1/2 alpha alpha of 1.6 h and 0.3 h and a median T1/2 beta of 5.0 h and 5.0 h respectively. Median plasma and cellular area under the curve (AUC) for a 24-h period amounted 6.2 micrograms.h/ml and 49.8 micrograms.h/ml respectively. In vitro cellular uptake was maximal at least within 30 minutes. No differential toxicity for CFU-GM and CFU-L was observed in relation to exposure time. Median IC50 for CFU-GM and CFU-L was 2.2, 1.8 and 1.6 micrograms/ml after incubation periods of resp. 0.08, 4 and 24 h. The corresponding m-AMSA concentration x time products to achieve 50% inhibition (IAUC50) were 0.18, 7.2 and 38.4 micrograms.h/ml, respectively. 48-h prestimulation of the clonogenic bone marrow cells with Human Placenta Conditioned Medium increased sensitivity (median 1.7 x) after 4 h incubation with mAMSA. Short exposure provides maximal, concentration-related, cellular uptake, resulting in effective inhibition of growth of clonogenic bone marrow cells.

S-phase DNA content and aneuploidy of immunophenotypic defined subpopulations in acute myeloid leukemia determined by multi-parameter flow cytometry

One of the major limitations of DNA flow cytometry (FCM) in hematologic malignancies is the lack of information about the proliferation activity of subpopulations of the heterogeneous bone marrow (BM) compartment. We studied the S-phase DNA content of immunophenotypically defined BM subpopulations (CD2+; CD19+; CD2/CD19+; glycophorin-A+; CD14+; CD13+; CD33+ and CD13/CD33+) in 18 patients with acute myeloid leukemia (AML), including three patients with M6 AML. The results were compared with the findings in twelve normal BM aspirates. The measurements were performed using a special protocol for bivariate FCM of DNA content and surface immunofluorescence (s-IF). In patients with AML the proportion of BM cells expressing the myelomonocytic and monocytic markers (M1-M5 AML) or erythroid marker (M6 AML) was expanded. However, in many patients other subpopulations were 4% or higher permitting the calculation of their S-phase DNA. No essential differences in median S-phase DNA percentages of the distinct subpopulations were observed between normal and leukemic bone marrow though the ranges in AML patients were much wider. These data suggest that AML is not characterized by an increased nor a decreased proliferation activity, but rather by a situation of cell growth independent to the normal regulatory mechanisms. Additional information was obtained upon DNA aneuploidy using CD2+ or CD2/CD19+ cells as an intrinsic DNA standard which allowed us to define differences in the DNA index as small as 2% as aneuploid. This approach appeared suitable for detecting small-degree numerical chromosomal aberrencies, as found by cytogenetics, in 4/6 cases.