Biomedical subjects
Publications and source records attributed to J de Wolf.
IMPLICATIONS: The successful treatment with recombinant factor VIIa of a patient experiencing intractable bleeding after cardiac surgery is described.
In the present study, we analyzed the capacity of CD34+/CD36- sorted bone marrow cells of myelodysplasia patients (n = 4) to differentiate along the erythroid lineage in the presence of erythropoietin (Epo) and mast cell growth factor (MGF). Two subgroups could be identified. In 6 patients, a normal number of burst-forming units-erythroid (BFU-Es) were cultured from CD34+/CD36- sorted cells. Cells from these patients did have the capacity to differentiate to colony-forming units-erythroid (CFU-Es) progenitors in cell suspension cultures with Epo plus MGF followed by Epo in the culture assay. Moreover, the cells became CD34-/CD36+/gly-cophorin A (GpA)+ after 7 days of culture with Epo plus MGF, a pattern comparable to that of normal progenitors. In contrast, in 8 patients, a different pattern was observed. No BFU-Es or a low number of BFU-Es were cultured from the CD34+/CD36- sorted cell fraction that was, in most of the cases, incapable of differentiating to CFU-E progenitors. Flow cytometry of the sorted population showed that, after 7 days of culture with Epo plus MGF, a high proportion of CD34+/CD36- cells persisted, whereas a low proportion of cells became CD34-/CD36+/GpA+. The unresponsiveness is not caused by the used growth factor combination, because the addition of interleukin-3 did not correct the defect. Evi-1 expression was studied in 9 cases to show whether an aberrant Evi-1 expression correlates with a disturbed erythroid development. Evi-1 expression was shown in 4 of 9 cases, whereas 3 of 9 cases did have a disturbed erythroid differentiation. In summary, the results show that the defects in the erythroid development in a subpopulation of patients with myelodysplasia is localized at an early stage of the erythroid differentiation and is associated with the persistent expression of the CD34 antigen and, in some cases, with the expression of Evi-1.
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We describe 2 sisters who presented with the hemolytic uremic syndrome (HUS) almost simultaneously. In both patients an upper airway infection with Haemophilus influenzae immediately preceding HUS may have been the environmental trigger. Fresh plasma infusion had only minor therapeutic effects but plasma exchange was followed by hematological remissions. One patient stayed dialysis dependent, the other had slow recovery of renal function on prolonged plasma exchange. These case histories suggest that in genetically predisposed patients HUS can be triggered by an infection with H. influenzae. Furthermore, when there is a poor response to plasma infusion recovery may be accelerated by plasma exchange.
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Differential velocity detection in the fovea was measured over a wide range of velocities (0.25-256 degrees/sec). Differential thresholds were minimum (about 6%) for intermediate velocities (4-32 degrees/sec). Velocity judgements were shown not to depend on duration judgments. The U-shaped curve relating differential velocity detection and velocity was preserved at different background levels and different contrasts. The physiological correlates of these observations are discussed.
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