Programmed cell death is an intrinsic feature of MDS progenitors, predominantly found in the cluster-forming cells.

Objective: Bone marrows (BM) of myelodysplastic syndrome (MDS) patients show increased proliferation and premature programmed cell death (PCD) in vivo as well as in vitro. We explored the proliferative capacity and apoptotic propensity of CD34+ progenitor cells of MDS patients excluding accessory cell interference.

Materials And Methods: CD34+/CD3-/CD19- cells of 5 MDS patients and 5 normal BM were sorted as single cells into single wells and were cultured in liquid medium.

Phenotypical and functional differences in germinative subpopulations derived from normal and psoriatic epidermis.

A model that explains how maintenance of normal homeostasis in human epidermis is achieved describes a heterogeneous cell population of stem cells (SC) and transit amplifying cells (TAC). There must be a tightly regulated balance between SC self-renewal and the generation of TAC that undergo a limited number of divisions before giving rise to postmitotic, terminally differentiated cells. To investigate whether this balance is disturbed in psoriatic epidermis, we have characterized flow sorted enriched SC and TAC using immunocytochemistry, flow cytometry, and real-time quantitative PCR.

The dynamic process of apoptosis analyzed by flow cytometry using Annexin-V/propidium iodide and a modified in situ end labeling technique.

Background: To study the apoptotic process in time, we used the following flow cytometric (FCM) techniques: phosphatidylserine (PS) translocation by Annexin-V (AnV), DNA fragmentation by in situ end labeling (ISEL), and propidium iodide (PI) staining. Because PS translocation is assumed to be an early feature of programmed cell death (PCD), we questioned if AnV positivity implies inevitable cell death.

Methods: Apoptosis was induced in Jurkat cells by gamma-irradiation, incubation with camptothecin (CPT), or cytosine beta-D-arabinofuranoside (Ara-C).

Cyclosporin increases cellular idarubicin and idarubicinol concentrations in relapsed or refractory AML mainly due to reduced systemic clearance.

The feasibility of adding both the multidrug resistance modulator cyclosporin (CsA) and granulocyte colony-stimulating factor (G-CSF) to a standard salvage regimen of idarubicin (IDA) and cytarabine was evaluated in patients with resistant or relapsed acute myeloid leukemia and myelodysplastic syndrome. Three patients received IDA 12 mg/m2/day, the next four patients 9 mg/m2/day. The dose of CsA was 16 mg/kg/day.

Triggering noncycling hematopoietic progenitors and leukemic blasts to proliferate increases anthracycline retention and toxicity by downregulating multidrug resistance.

Expression of the multidrug resistance (MDR) mechanisms P-glycoprotein (Pgp) and MDR-related protein (MRP) decrease cellular retention and consequently cytotoxicity of anthracyclines. MDR is expressed on normal human hematopoietic progenitors and leukemic blasts. Normal CD34(+) progenitors showed rhodamine efflux in 20% to 30% of the cells, which could be blocked by verapamil.

Idarubicin DNA intercalation is reduced by MRP1 and not Pgp.

Currently available data regarding the substrate specificity of the multi-drug resistance (MDR) mechanisms P-glycoprotein (Pgp) and MDR-associated protein (MRP1) for idarubicin are inconclusive. A multiparameter flow cytometry method was developed which allows simultaneous quantitative measurement of total cellular fluorescence and the amount of anthracyclines intercalated into the DNA. Anthracycline DNA intercalation was measured by fluorescence resonance energy transfer (FRET) between Hoechst 33342 and anthracyclines.

The role of the different CD34 epitopes in detection and positive selection of CD34+ bone marrow and peripheral blood stem cells.

Positive selection of CD34+ cells is an attractive approach to reduce tumour cell contamination in bone marrow (BM) and peripheral blood progenitor cell (PBPC) autografts in malignancies not expressing CD34. All current selection methods use monoclonal antibodies (MoAbs) specific for the class I or class II CD34 epitopes, while for detection most investigators use class III MoAbs. Since the distribution of the different CD34 epitopes on haematopoietic progenitors differs, we studied their significance in CD34+ selection procedures.

Automatic analysis of growth onset, growth rate and colony size of individual bone marrow progenitors.

A method for automatic enumeration of proliferating bone marrow progenitors after single cell sorting is described. The system is based on regular inverse microscopy, recording with a video camera, and image analysis using dedicated software on an Apple computer. Single CD34+ progenitor cells were sorted in 96-well plates.

A low but functionally significant MDR1 expression protects primitive haemopoietic progenitor cells from anthracycline toxicity.

Pgp is expressed on normal haemopoietic progenitor cells. The significance of the efflux pump in protecting normal progenitors for anthracycline toxicity is not defined and is the subject of this study. Pgp was measured in CD34+ progenitors with a rhodamine efflux assay.

Anti-endothelial cell antibodies in sera of patients with autoimmune diseases: comparison between ELISA and FACS analysis.

In some patients suffering from rheumatoid arthritis (RA), vasculitis is a clear clinical manifestation, mentioned as rheumatoid vasculitis (RV). Autoantibodies directed against endothelial cells (AEA) have been implicated in the pathogenesis of this disorder, and it has been suggested in a number of studies that testing for AEA should be included in diagnosing RV. To test this hypothesis, we have evaluated the presence of AEA in sera of patients suffering from various autoimmune diseases, employing an ELISA with fixed cultured endothelial cells (EC).

Diffuse CNS involvement in systemic lupus erythematosus: intrathecal synthesis of the 4th component of complement.

In extracerebral systemic lupus erythematosus (SLE), the complement system plays a prominent pathogenic role, and decreased serum concentration of the 4th component (C4) is a reliable indicator of systemic disease activity. In diffuse CNS-SLE, however, the pathogenic role of complement is less clear. In 12 patients with active diffuse CNS-SLE presenting with delirium (4), organic personality syndrome (3), or generalized seizures (5), we determined the CSF indexes of the complement components C3, C4, and factor B, and of IgG, IgA, and IgM.

Antiperinuclear factor: indicator of more severe disease in seronegative rheumatoid arthritis.

The specificity of antiperinuclear factor (APF) for patients with rheumatoid arthritis (RA) is well documented. It is unknown whether detection of these antibodies adds information to the detection of rheumatoid factor (RF). In a group of 132 patients with RA, 94 were RF positive.

Cross-reactivity of anti-DNA antibodies with proteoglycans.

Ten sera of patients with systemic lupus erythematosus (SLE) were tested in an enzyme linked immunosorbent assay for their ability to react with glycosaminoglycans, constituents of proteoglycans, in relation to their anti-DNA reactivity. The SLE sera reacted with hyaluronic acid and chondroitin sulphate and this reactivity correlated with the anti-DNA activity of these sera. By contrast, sera obtained from patients with other autoimmune diseases or normal sera lacked any of these reactivities.

Anti-nuclear matrix antibodies in mixed connective tissue disease.

Purified serum antibodies of patients suffering from mixed connective tissue disease were tested for their immunological specificity against nuclear constituents of HeLa S3 cells. In the indirect immunofluorescent staining technique, using cells and nuclei as targets, a typical speckled intranuclear staining pattern was obtained, that persisted after degradation and extraction of all nucleic acids and their associated proteins. This treatment of nuclei with detergents, DNase, RNase and high salt concentrations leave intact only the so-called nuclear matrix which is an intranuclear proteinaceous network.

Variations of the phosphorylation of 1-beta-D-arabinofuranosylcytosine (ARA-C) in human myeloid leukemic cells related to the cell cycle.

Bone marrow cells of five patients with acute myeloid leukemia were fractionated by means of counterflow centrifugation (elutriation). The different fractions were enriched with cells belonging to subsequent stages of the cell cycle. Cytokinetic evaluation of these cell fractions was performed by [3H]thymidine autoradiography, [3H]thymidine incorporation and DNA/RNA-flow cytometry.

Cytosine arabinoside binding to human plasma proteins.

The interaction of cytosine arabinoside (Ara-C) with human plasma proteins was investigated by means of ultrafiltration and ultracentrifugation. The results obtained with both methods did not differ significantly. Ara-C binding was studied at plasma levels within the therapeutic range (0.