Shear stress activation of platelet glycoprotein IIb/IIIa plus von Willebrand factor causes aggregation: filter blockage and the long bleeding time in von Willebrand's disease

The article explores the finding that high shear alone applied to normal, native blood results in platelet aggregation. A filter with tortuous capillary-sized channels permits a study of the effect of shearing forces at different pressures. Native, heparinized, citrated and EDTA blood and platelet-rich plasma (PRP) were forced through the filter. Normal and von Willebrand's blood were studied, as were the effects of antibodies to platelet glycoproteins (GPr) and to von Willebrand's factor (vWf) and of "membrane-active" drugs. Normally, the filter blocked at 40 mmHg but not at 5 mmHg. Transmission electronmicroscopy of the filter at 40 mmHg showed blockage by platelet aggregates. Initially, the mean transit time through the filter was 8 milliseconds. Platelet retention in the filter occurred in two phases. From 0 to 3 seconds, only high-shear, vWf, and GPrIIb/IIIa were required. From 10 to 20 seconds, retention presumably involved these three attributes, but divalent cations were also essential. Only this phase was inhibited by some membrane-active drugs. ADP- and thrombin- induced aggregation requires GPrIIb/IIIaand fibrinogen. Shear-induced blocking of the filter by blood with a normal concentration of fibrinogen requires GPrIIb/IIIa and vWf. This indicates a different type of exposure of GPrIIb/IIIa. The long bleeding time in vW disease highlights the absolute requirement for vWf and emphasizes the difference in exposure of GPrIIb/IIIa induced by shear stress. Evidently, a process similar to that occurring in the filter is required in normal capillary hemostasis.     

Stem cell factor enhances interleukin-3 dependent induction of 68-kD calmodulin-binding protein and thymidine kinase activity in NFS-60 cells

Stem cell factor (SCF) is known to act synergistically with other hematopoietic factors in increasing the colony formation of hematopoietic progenitor cells. We have shown that interleukin-3 (IL-3)- dependent proliferation of NFS-60 cells is associated with the induction of a specific calmodulin-binding protein of about 68 kD (CaM- BP68). To evaluate the relationship between proliferative stimulation and the induction of CaM-BP68 by cytokines, we examined whether the increased proliferative potential of NFS-60 cells in response to SCF is reflected in an increased induction of the CaM-BP68. We observed that SCF alone has a limited effect on proliferative stimulation and on the induction of CaM-BP68 in factor-deprived NFS-60 cells. However, when combined with IL-3, granulocyte colony-stimulating factor (G-CSF), or IL-6, it caused a significant increase in cytokine-dependent proliferative stimulation, as well as in the induction of CaM-BP68. Furthermore, an increase in IL-3-dependent induction of CaM-BP68 in the presence of SCF coincided with a corresponding increase in thymidine kinase activity, whose expression is linked to G1/S transition of the cells. At low concentrations SCF caused a synergistic increase in IL-3- dependent induction of both CaM-BP68 and thymidine kinase activity. In contrast to the changes in CaM-BP68 and thymidine kinase activity, no significant changes in DNA polymerase alpha were observed in factor- deprived NFS-60 cells in response to IL-3 and/or SCF. These observations suggest an increased expression of CaM-BP68 and thymidine kinase are associated with the synergistic effect of SCF on factor- dependent proliferation of hematopoietic progenitor cells.     

Treatment of poor-prognosis, newly diagnosed acute myeloid leukemia with ara-C and recombinant human granulocyte-macrophage colony- stimulating factor

We administered recombinant granulocyte-macrophage colony-stimulating factor (GM-CSF) (120 micrograms/m2/d by continuous intravenous [IV] infusion) to 12 patients with newly diagnosed acute myeloid leukemia (AML) at relatively high risk of early death during remission induction. GM-CSF began 3 days after completion of induction chemotherapy (ara-C 1.5 g/m2 d x 4 days by continuous IV infusion after a 3 g/m2 bolus). Rates of fatal infection (42%), pneumonia and/or sepsis (83%), and CR (50%) did not differ significantly (P less than .05) from those observed after administration of the identical chemotherapy without GM-CSF to 53 historical controls with newly diagnosed AML at similarly high risk of early death. There were no significant differences between the GM-CSF-treated and the historical groups in the time required to reach neutrophil counts of 500 or 1,000/microL after administration of chemotherapy. Four patients died of infection before they could have benefited from the earliest recovery of neutrophil count observed in patients who entered CR. Growth of leukemia after GM-CSF administration was observed in only 1 of the 8 patients who survived long enough for response to induction therapy to be fully evaluated. This observation suggests that it might be safe to undertake larger, randomized studies, perhaps using earlier administration of GM-CSF, to definitively determine the role of GM-CSF added to chemotherapy in patients with newly diagnosed AML.     

Second malignancies after treatment for laparotomy staged IA-IIIB Hodgkin's disease: long-term analysis of risk factors and outcome

The survival of patients with Hodgkin's disease has dramatically improved over the past 30 years because of advances in treatment. However, concern for the risk of long-term complications has resulted in a number of trials to evaluate reduction of therapy. The consequences of these trials on recurrence, development of long-term complications, and survival remain unknown. One major consequence of successful treatment of Hodgkin's disease is the development of second malignant neoplasms. We sought to determine the factors most important for development of second tumors in pathologically staged and treated Hodgkin's disease patients followed for long intervals to provide background information for future clinical trials and guidelines for routine patient follow-up. Between April 1969 and December 1988, 794 patients with laparotomy staged (PS) IA-IIIB Hodgkin's disease were treated with radiation therapy (RT) alone or combined radiation therapy and chemotherapy (CT). There were 8,500 person-years of follow-up (average of 10.7 person-years per patient). Age and gender-specific incidence rates were multiplied by corresponding person-years of observation to obtain expected numbers of events. Observed to expected results were calculated by type of treatment, age at treatment, sex, and time after Hodgkin's disease. Absolute (excess) risk was expressed as number of excess cases per 10,000 person-years. Seventy-two patients have developed a second malignant neoplasm. Eight patients developed acute leukemia, 10 had non-Hodgkin's lymphoma (NHL), and 53 patients developed solid tumors at a median time of 5 years, 7.25 years, and 12.2 years, respectively, after Hodgkin's disease. One patient developed multiple myeloma 16.5 years after Hodgkin's disease. The relative risk (RR) of developing a second malignancy was 5.6. The absolute excess risk per 10,000 person-years (AR) of developing a second malignancy was 69.6 (7.0% excess risk per person per decade of follow-up). The highest RR occurred for the development of leukemia (RR = 66.2), however because of the low expected risk, the AR was only 9.3. The RR of solid tumors after Hodgkin's disease was lower (4.7); however, the AR was greater (49) than for acute leukemia. Among the solid tumors, breast, gastrointestinal, lung, and soft tissue cancers had the highest absolute excess risks. The risk for developing breast cancer after Hodgkin's disease was greatest in women who were under the age of 25 at treatment. The most significant risk factor for the development of both leukemia and solid tumors was the combined use of radiation therapy and chemotherapy. The RR following RT alone was 4.1 (AR = 51.1); for RT + CT (initially or at relapse) the RR was 9.75 (P < 0.05, nonoverlapping confidence limits, AR = 123.9). Survival following development of a second malignancy was poor in patients with leukemia, gastrointestinal tumors, lung cancer, and sarcoma. Survival from other malignancies including NHL and breast cancer was more encouraging. Second malignant neoplasms are a major cause of late morbidity and mortality following treatment for Hodgkin's disease. The most significant risk factor for the development of second tumors is the extent of treatment for Hodgkin's disease. Recommendations are presented for both prevention and early detection of these tumors.     

The appropriate use criteria: Improvements for its integration into real world clinical practice

The purpose of this position statement is to suggest ways in which future appropriate use criteria (AUC) for coronary revascularization might be restructured to: (1) incorporate improvement in quality of life and angina relief as primary goals of therapy, (2) integrate the findings of recent trials into quality appraisal, (3) employ the combined information of the coronary angiogram and invasive physiologic measurements together with the results of stress test imaging to assess risk, and (4) recognize the essential role that patient preference plays in making individualized therapeutic decisions. The AUC is a valuable tool within the quality assurance process; it is vital that interventionists ensure that percutaneous coronary intervention case selection is both evidence-based and patient oriented. Appropriate patient selection is an important quality indicator and adherence to evidence-based practice should be one metric in a portfolio of process and outcome indicators that measure quality.     

Treatment of patients over 50 years of age with acute myelogenous leukemia with a combination of rubidazone and cytosine arabinoside, vincristine, and prednisone (ROAP)

We administered a combination of rubidazone, cytosine arabinoside, vincristine, and prednisone (ROAP) to 91 patients with acute myelogenous leukemia who were 50 yr of age or older. These patients had been identified in previous studies to be a group with a relatively poor prognosis. One-third of the patients had an antecedent hematologic disorder prior to treatment. Forty patients (48%) obtained a complete hematologic and clinical remission. A history of an antecedent hematologic disorder, male sex, and absence of Auer rods were adverse factors for achieving remission in this older population. More than half of the patients achieved remission in one course. The major cause of failure to obtain a remission was death due to infection, 40% of which were caused by fungi. Resistance to chemotherapy, although uncommon, was noted more frequently in patients with an antecedent hematologic disorder. Univariate and multivariate prognostic factor analysis was used to compare these patients with a historical control group treated with a program in which adriamycin was used instead of rubidazone (AdOAP). No significant difference in remission rate was detected. Cyclocytidine was used as a maintenance agent in this study, and while the median remission duration was only 37 wk, 30% of patients are expected to be in remission for 2 yr. Chemotherapy programs combining an anthracycline with cytosine arabinoside, given to older patients in similar fasion to younger patients will achieve remissions in one-half of a group of older patients. These remissions are of comparable quality to those of younger patients. Mathematical models derived from analysis of prognostic factors are of use in identifying patients likely to fail these programs who are in need of innovative approaches to treatment.     

Variation in fetal hemoglobin parameters and predicted hemoglobin S polymerization in sickle cell children in the first two years of life: Parisian Prospective Study on Sickle Cell Disease

Intracellular hemoglobin S (HbS) polymerization is most likely to be the primary determinant of the clinical and biologic manifestations of sickle cell disease (SCD). Fetal hemoglobin (HbF) does not enter the HbS polymer and its intracellular expression in sickle erythrocytes inhibits polymerization. HbF levels, high at birth but decreasing thereafter, protect the newborn from the clinical manifestations of this hemoglobinopathy. We have measured the sequential changes in HbF, F reticulocytes, and F cells in the first 2 years of life in 25 children with SCD and compared the results with those obtained in 30 normal children (AA). We have also calculated HbF per F cell (F/F cell), the preferential survival of F cells versus non-F cells, as measured by the ratio F cells versus F reticulocytes (FC/FR) and polymer tendency at 40% and 70% oxygen saturation. HbF levels decreased from about 80.4% +/- 4.0% at birth to 9.2% +/- 2.9% at 24 months. During this time, we observed a regular decrease of the F reticulocytes and the F cells. The kinetics of the decline of F/F cell was comparable with the decline of HbF, rapid from birth (mean, 27.0 +/- 3.6 pg) to 12 months of age (mean, 8.5 +/- 1.5 pg) and then slower from 12 to 24 months of age (mean, 6.2 +/- 1.0 pg) in the SCD children. In the AA children, the decrease in HbF, due to changes in both numbers of F cells and F/F cell, was more precipitous, reaching steady-state levels by 10 months of age. Calculated values for mean polymer tendency in the F-cell population showed that polymerization should begin to occur at 40% oxygen saturation at about 3 months and increase progressively with age, whereas polymerization at 70% oxygen saturation would not occur until about 24 months. These values correspond to HbF levels of 50.8% +/- 10.8% and 9.2% +/- 2.9%, respectively, and F/F cell levels of 15.6 +/- 4.5 pg and 6.2 +/- 1.0 pg, respectively. In the non--F-cell population, polymerization was expected at birth at both oxygen saturation values. Three individuals had significantly greater predicted polymerization tendency than the remainder of the group because of early decreases in HbF. These individuals in particular, the remainder of the cohort, as well as other recruited newborns, will be studied prospectively to ascertain the relationship among hematologic parameters, which determine polymerization tendency and the various clinical manifestations of SCD.     

Human platelet cytoskeletons: specific content of glycolipids and phospholipids

The lipid composition of platelet cytoskeletons was analyzed. Triton X- 100 (0.5%) was used to prepare cytoskeletons from thrombin-treated platelets. The lipid/protein ratio of platelet cytoskeletons was 0.260 and the phospholipid/protein ratio was 0.177, which were comparable to the ratios present in platelets. However, there was a selective enrichment of platelet lipids in platelet cytoskeletons. Only 2 of the 5 major platelet phospholipids were detected. About 14% platelet sphingomyelin and 2% platelet phosphatidylcholine were present in platelet cytoskeletons. Only 1 of the 4 platelet neutral glycolipids, trihexosyl ceramide, was detected and was about 7% of that in intact platelets. Two percent of platelet hematoside, the predominant ganglioside in platelets, was found in cytoskeletons. Six percent of platelet cholesterol was present in platelet cytoskeletons, while no other neutral lipid could be detected. The study demonstrates that the lipid/protein ratio of platelet cytoskeletons is similar to that in platelets, but the composition of cytoskeleton lipids is specific and distinctly different from that in platelets. The selective glycolipid and phospholipid composition of cytoskeletons may be important for cytoskeleton and platelet function.     

Evaluation of AMSA in previously treated patients with acute leukemia: results of therapy in 109 adults

AMSA was evaluated in the treatment of 109 adults with previously treated acute leukemia. Of the 102 evaluable patients, 82 had AML, 17 ALL, and 3 CML in blastic phase. A number of different dose schedules of AMSA were explored, and we conclude that the optimum dose of AMSA for remission induction in acute leukemia is 120 mg/sq m/day for 5 days. Complete remissions were observed in 23 (28%) patients with AML and in 1 patient with ALL. Patients who achieved complete remission were maintained on AMSA using a dose of 30-40 mg/sq m/day for 5 days repeated at 4-wk intervals. The median duration of complete remission was 12 wk (3-59 wk), and the responders survived significantly longer than the failures (27 wk versus 8 wk, p = 0.002). The side effects associated with AMSA therapy included mild nausea and vomiting, stomatitis, diarrhea, phlebitis, alopecia, and myelosuppression-related infections. Our results indicate that AMSA is a useful new antileukemic agent for the treatment of relapsed acute leukemia and appears to have activity comparable to that of the currently available drugs, such as cytarabine and the anthracycline antibiotics.