Interrelationship between mitosis and endomitosis in cultures of human megakaryocyte progenitor cells [published erratum appears in Blood 1987 May;69(5):1547]

Sera from dogs rendered aplastic by total-body irradiation stimulate human bone marrow megakaryocyte progenitors to form megakaryocyte colonies in plasma clot cultures. In this investigation, we evaluated the effects of varying concentrations of such sera on both the mitotic and endomitotic phases of human megakaryocyte development in vitro. When low concentrations of aplastic canine sera (2.5% to 5.0% [vol/vol]) were added to cultures of human peripheral blood mononuclear cells in place of normal AB serum, megakaryocyte colony formation was augmented fivefold, cell numbers per colony increased approximately 2.5- fold, and the geometric mean megakaryocyte ploidy almost doubled. Further increasing the aplastic canine serum concentration from 10% to 30% (vol/vol) stimulated no additional colony formation. However, there was a further augmentation of cell numbers per colony associated with a progressive decrease in the mean megakaryocyte ploidy. Megakaryocyte cultures were harvested after 7, 12, 15, and 19 days of incubation, and these demonstrated that the lower mean ploidy values found at the higher concentrations of aplastic canine serum did not result from delayed endoreduplication. At all aplastic serum concentrations evaluated, there existed a strong correlation between nuclear ploidy and cell diameter. We conclude that both the mitotic and endomitotic events in human megakaryocytopoiesis may be influenced by a factor or factors present in aplastic canine serum. At lower in vitro concentrations, such sera stimulate both mitosis and endomitosis, which promotes the development of megakaryocyte colonies composed of larger cells with a higher mean ploidy. With increasing aplastic serum concentrations, colony formation plateaus and mitosis is favored over endomitosis. This results in colonies composed of more numerous but smaller megakaryocytes with a lower mean ploidy. Our data suggest that the size and extent of polyploidization that can be achieved by a developing megakaryocyte may be influenced by the mitotic prior history of its immediate precursor cell.     

Assessment of the branches of the pulmonary artery by 2-dimensional echocardiography

Sixty three cases of Fallot's tetralogy aged from 1 month to 30 years old, were studied by 2D echocardiography to evaluate the diameter of the pulmonary arteries and to detect stenosis of the main pulmonary arteries. The right pulmonary artery was visualised clearly enough to be measured in all 63 cases whereas the left pulmonary artery could only be adequately recorded in 58/63 cases. The junction of the two pulmonary arteries was confirmed by 2D echo in 61/63 cases; in two cases, the left pulmonary artery was not connected (2/63), confirmed at angiography and surgery. Six stenoses of the pulmonary arteries, confirmed surgically (6/7), were detected by 2D echo but there were also 3 false positive results. The pulmonary arteries were measured from suprasternal views; the values obtained ranged from 3 to 15 mm. There was a good correlation with the angiographic measurements (R = 0.81 for the right pulmonary, and R = 0.82 for the left pulmonary arteries). Good correlations were also observed between the peroperative and 2D echo measurements (R = 0.84 for the right pulmonary; R = 0.77 for the left pulmonary artery). 2D echocardiography is a non-invasive reliable technique for visualising the pulmonary arteries and their origin, for measuring the calibre of these vessels and for detecting severe proximal pulmonary artery stenosis.     

Human cytomegalovirus increases constitutive production of interleukin- 6 and leukemia inhibitory factor by bone marrow stromal cells

Human cytomegalovirus (CMV) infection is often associated with myelosuppression and acute inflammatory reaction in immunocompromised patients. We have previously documented that CMV exposure of bone marrow (BM) stromal cells reduces the capacity of these cells to support hematopoiesis because of a decreased production of colony- stimulating factors. This study examines the potential role of CMV on constitutive and lipopolysaccharide (LPS)-stimulated production of cytokines involved in inflammatory reaction, interleukin-6 (IL-6) and leukemia inhibitory factor (LIF) by BM stromal cells. The release of IL- 6 was already detectable 2 hours post CMV-infection (2.5-fold increase in production) and the cumulative production of IL-6 after 5 days of infection was 23 +/- 1.2 ng/mL (ninefold increase in production). CMV was also able to induce a time-dependent production of LIF that was maximal 8 hours after CMV infection (2.5-fold increase in production). Concomitantly, there was no detectable release of granulocyte colony- stimulating factor (G-CSF) and granulocyte-macrophage CSF (GM-CSF) by CMV-infected stromal cells. The similar IL-6 and LIF production in the presence of polymyxin B ruled out the possibility that this increase could be caused by contamination of the viral stock by endotoxin. In addition, ultraviolet-inactivated virus behaved similarly to live virus and caused the release of IL-6 and LIF. However, heat-inactivated CMV was unable to induce IL-6 and LIF secretion by BM stromal cells. The production of IL-6 and LIF was also evaluated after stimulation by LPS. After 5 days of CMV exposure, the LPS-stimulated production of IL-6 and LIF was significantly lower than uninfected controls. This LPS-induced release of cytokine production was found to be dependent of viral replication. The experiments have shown that CMV is a potent inducer of IL-6 and LIF with differential effect on constitutive and LPS- stimulated cytokine production by stromal cells; we suggest that CMV induction of IL-6 and LIF during the first hours of infection could play a role in CMV-induced inflammatory reaction. Moreover, our results show that human CMV can disturb the balanced cytokine network involved in the regulation of hematopoiesis.     

Apoptosis in blood diseases Review - new data

In this report we reviewed the recent data regarding the involvement of apoptosis or progammed cell death in hematological diseases. We summarized new features of apoptosis including high molecular weight DNA fragmentation and programmed cell death of enucleated cells. We described the recent contributions about the three oncogenes bcl-2, p53 and c-myc. New inducers and inhibitors of apoptosis have been reported, particularly the role of stromal environment, thrombopoietin, erythropoïetin and flt-3 ligand has been mentioned. Apoptosis has been studied in red cell pathology: polycythemia, thalassemia and deficiency in folates, vitamin B12, iron and G⁶PD. Recently, the involvement of programmed cell death has been documented in bone marrow failure and myelodysplasia. In Acute Leukemia, the therapeutic action of numerous drugs has been proven by their in vitro apoptotic effect. The resistance of malignant cells to apoptosis, in Chronic Myeloid Leukemia, due to bcr-abl oncogene, has been partially explained by conformational changes in p53 expression and is reversed by retinoic acid. Numerous reports in Chronic Lymphocytic Leukemia have documented the major role of apoptosis in this disease, especially in therapeutic efficacy of Chlorambucil, Fludarabine and Methylxanthine derivatives. At least, in Myeloma, it has been shown that apoptosis is induced by dexamethasone and HMBA, and inhibited by interleukine 6 that prevents activation of SAP Kinases.     

Combination of quinine as a potential reversing agent with mitoxantrone and cytarabine for the treatment of acute leukemias: a randomized multicenter study

A phase III prospective randomized multicenter study was performed to determine whether quinine could improve the response rate of poor-risk acute leukemias (ALs) to standard chemotherapy including a multidrug resistance (MDR)-related cytotoxic agent. The rationale of the study was based on the negative prognostic value of MDR phenotype in ALs and the ability of quinine to reverse this phenotype both in vitro and ex vivo. Three hundred fifteen patients (median age, 49 years; range, 16 to 65) with relapsed (n = 108) or refractory (n = 32) acute myeloblastic leukemia (AML), relapsed (n = 27) or refractory (n = 9) acute lymphoblastic leukemia (ALL), secondary AL (n = 22) or blastic transformation of myelodysplastic syndrome ([MDS] n = 74) or myeloproliferative syndrome ([MPS] n = 43) were randomly assigned to receive mitoxantrone ([MXN] 12 mg/m2/d, days 2 to 5) and cytarabine ([Ara-C] 1 g/m2/12 h, days 1 to 5) alone or in combination with quinine (30 mg/kg/d, days 1 to 5; continuous intravenous infusion beginning 24 hours before MXN infusion). Side effects of quinine were observed in 56 of 161 quinine-treated patients and disappeared in all but four cases after one or two 20% dose decreases. Sera from quinine-treated patients showed increased MXN uptake in an MDR-positive cell line compared with matched sera obtained before quinine infusion. Quinine induced a significant increase in the incidence of nausea, vomiting, mucositis, and cardiac toxicity. A complete response (CR) was observed in 85 of 161 patients (52.8%) from the quinine-treated group versus 70 of 154 patients (45.5%) in the control group (P = .19). The most important differences between quinine and control group CR rates were observed in patients with refractory AMLs and blastic transformation of MDS and MPS. The CR rate was higher in P-glycoprotein-positive cases, although the difference was not significant. Failure of the regimen due to blastic persistence or blast number increase was higher in the control group (61 of 154 patients) than in the quinine group (45 of 161, P = .04). Early death was observed in eight cases (four in each arm) and death in aplasia in 27 cases (20 in quinine group v seven in control group, P = .01). The significant increase of toxicity in the quinine arm could have masked the clinical benefit of MDR reversion in poor- risk ALs.     

Double isthmic coarctation of the aorta: "tandem" coarctation

A second case of double coarctation of the thoracic aorta is reported, the first having been observed at the Marie-Lannelongue Surgical Center in an older child. This case was a 3 months infant in which the missed pre- and postoperative diagnosis led to reoperation after control catheter and angiographic studies. These investigations were carried out one month after the first operation because of persistent severe cardiac failure. Surgical cure in two stages consisted in a Waldhausen plastic enlargement procedure and a Crafoord-type resection anastomosis, ensuring the best chances for a good result.