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C Demur

Publications and source records attributed to C Demur.

33 records · Page 2Linked to original sources
PubMed1994

Effect of the protein kinase C inhibitor staurosporine on chemosensitivity to daunorubicin of normal and leukemic fresh myeloid cells.

The effect of the protein kinase C (PKC) inhibitor staurosporine (ST) on the chemosensitivity of normal (colony-forming unit granulocyte-macrophage [CFU-GM]) and leukemic (acute myeloid leukemia-CFU [AML-CFU]) myeloid progenitors to daunorubicin (DNR) was evaluated. Primary colony inhibition assays allowed us to characterize two distinct groups of AML, a DNR-resistant group (patients no. 1 through 6), which displayed significantly lower DNR sensitivity than normal CFU-GM (D50 = 11.3 +/- 1.4 ng/mL v 1.8 +/- 0.5 ng/mL, after 7 days of exposure, respectively; P < 0.01) and a DNR-sensitive group (patients no. 7 through 12) with D50 = 2.7 +/- 0.4 ng/mL. This classification remained unaltered when assessed by secondary colony inhibition assay (evaluating the self-renewal fraction of AML-CFU) or by viability assay (evaluating the ultimately differentiated blast cell population), suggesting that the DNR sensitivity profile in maintained throughout AML-CFU differentiation. DNR resistance of the differentiated blast cell population was not correlated with the level of P-glycoprotein (P-gp) expression but rather with the ability to extrude rhodamine 123 (Rh123). ST used at subtoxic concentrations induced a twofold to threefold enhancement of DNR cytotoxicity, increased Rh123 accumulation, and decreased Rh123 efflux kinetics in resistant AML cells. These effects were observed for ST concentrations much lower than those required to displace the P-gp-binding probe azidoprazosin, suggesting that ST might act through its PKC inhibitory effect and not through P-gp binding. Finally, this study provides evidence that DNR resistance in AML cells is, at least in part, related to the multidrug-resistance (MDR) phenotype. Because P-gp function can be downregulated by ST, it seems likely that the MDR pheno-type can be functionally regulated by cellular signalization in AML cells.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1994

Intensified conditioning regimen with busulfan followed by allogeneic BMT in children with myelodysplastic syndromes.

Four consecutive children with myelodysplastic syndromes (MDS) underwent matched allogeneic bone marrow transplantation (BMT). Ages ranged from 3.2 to 6.3 years. Diagnosis was assessed according to FAB classification: refractory anemia-RA (n = 1), RA with excess of blasts (RAEB) (n = 1), and juvenile chronic myelogenous leukemia (JCML) (n = 2). Initial treatment included transfusions for all of them, splenectomy (n = 2) and chemotherapy (n = 1). Patients were all prepared with busulfan 21 mg/kg (480 mg/m2), cytosine arabinoside 24,000 mg/m2, melphalan 140 mg/m2. Graft-versus-host disease (GVHD) prophylaxis associated cyclosporine-methotrexate. Engraftment was prompt and complete in all children. Toxicity included severe mucositis (n = 3), moderate veno-occlusive disease (n = 2), acute GVHD (n = 3), chronic GVHD (n = 1). Sequelae have not yet been seen. All patients are alive and disease-free with a follow-up ranging from 7 to 35 months, with a Karnofsky score of 90-100%. Combined busulphan conditioning can offer an alternative to total body irradiation-based regimens in order to avoid late side-effects in children.

Anemia, Refractory↗
PubMed1993

Effects of H-7 and staurosporine on proliferation and self-renewal of acute myeloid leukemia progenitors.

In this study, we compared the impact of two protein kinase (PK) inhibitors, H-7 and staurosporine, on the normal myeloid progenitors (CFU-GM) and acute myeloid leukemia progenitors (AML-CFU) proliferation measured by in vitro clonogenic assay. H-7 and staurosporine displayed a biphasic dose-effect on both CFU-GM and AML-CFU recovery. At the lowest concentration range (0.1 microM to 20 microM for H-7 and 0.1 nM to 1 nM for staurosporine), we observed growth stimulation whereas higher concentrations induced dose-dependent growth inhibition. Moreover, AML-CFU proved to be significantly more sensitive to the inhibitory effect of both H-7 and staurosporine than CFU-GM (3.16- and 2.12-fold, respectively). These results were further confirmed with comparable murine cell line models (FDC-P1, a hematopoietic cell line generated from normal bone marrow and WEHI, a myelomonocytic leukemia cell line). Furthermore, we report that both H-7 and staurosporine present similar inhibitory effects on proliferation (PE1) as on self-renewal (PEs) of AML-CFU. In an attempt to understand more fully the mechanism of action of H-7 and staurosporine, we investigated their impact (when used at their D50) on the human myelogenous leukemia cell line, K562. H-7 and staurosporine induced a transient decrease of cell growth, between 0 and 24 hours, and produced a transient blockade of K562 cells in the S-phase, either 24 or 48 hours after the addition of staurosporine and H-7, respectively.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1992

t(9;11)(p22;q23) translocation in blastic phase of chronic myeloid leukemia.

A patient with chronic myeloid leukemia showed clonal karyotypic evolution, with the appearance of an i(17q) and t(9;11)(p22;q23). This case sheds light upon leukemogenic events related to t(9;11)(p22;q23). The presence of t(9;22) and t(9;11) in the same clone showed that t(9;11) may affect a pluripotent stem cell, thus accounting for t(9;11) in both lymphoid and monocytic leukemias. In this patient, t(9;11) could not be related to a prior cytotoxic exposure and was instead the result of natural evolution of chronic myeloid leukemia. Furthermore, this led us to assume that the phenotype of blast cells may be determined by a chromosome abnormality. A phenotypic conversion from myeloblastic to undifferentiated morphologic aspect was observed when t(9;11) was detected, suggesting that t(9;11) may have induced a loss in differentiation of blast cells affected by this change. This assumption is in agreement with the putative presence of genes activated in pluripotent progenitors by 11q23 rearrangements.

Blast Crisis↗
PubMed1992

Sensitivity of fresh acute myeloid leukemia cells to etoposide: relationship with cell growth characteristics and DNA single-strand breaks.

In this study, we evaluated the individual in vitro sensitivity of fresh acute myeloid leukemia (AML) cells to VP-16, and attempted to correlate VP-16 cytotoxicity with AML cell growth characteristics and drug-induced DNA single-strand breaks (SSB). Primary (PE1) colony inhibition assays allowed us to characterize two distinct groups of AML: group I (patients 1 through 6), which displayed sensitivity to VP-16 similar to that of normal CFU-GM (IC90 of 20.52 +/- 2.44 micrograms/mL v 20.48 +/- 2.23 micrograms/mL after 1 hour drug exposure, respectively); and group II (patients 7 through 11), which was more sensitive to VP-16 (IC90 of 7.26 +/- 2.93 micrograms/mL, P = .004). Subsequently, groups I and II were termed normosensitive and hypersensitive, respectively. This objective VP-16 sensitivity classification, as determined by PE1, remained unaltered when assessed by secondary (PE2) colony inhibition assay (evaluating the self-renewal fraction of AML progenitors), or by cytofluorometric viability assay (evaluating the ultimately differentiated blast cell population). These findings would suggest that individual sensitivity to VP-16 of a particular cell population is maintained throughout CFU-AML differentiation. Finally, we report that sensitivity of AML cells to VP-16 did not correlate either with cell growth characteristics or with SSB generation. Indeed, AML cell sensitivity to VP-16 appeared more closely related to DNA repair kinetics after drug removal, ie, hypersensitivity being essentially characterized by a prolonged retention of SSB during the posttreatment period. Interestingly, the established HL-60 cell line, which presented greater sensitivity to VP-16 cytotoxicity than KG1, HEL, and K562, was also found to exhibit delayed DNA SSB repair kinetics, as compared with the other AML cell lines. These results suggest that hypersensitivity to VP-16 of some AML cells may be related to a deficient DNA-repair mechanism.

Cell Division↗
PubMed1992

Prognostic significance of karyotype in a twelve-year follow-up in childhood acute lymphoblastic leukemia.

We report a follow-up of 49 children with acute lymphoblastic leukemia (ALL) diagnosed between 1972 and 1978 (follow-up 12-18 years). This series allowed us to analyze the predictive value of karyotype in a long-term follow-up. Karyotypes were abnormal in 33 cases (67.3%): pseudodiploidy in 11 (22.4%), hyperdiploidy > 50 chromosomes in 8 (16.3%), hyperdiploidy 47-50 chromosomes in 11 (22.4%), and hypodiploidy in 3 cases (6.1%). Event-free survival (EFS) and survival studies showed that the outcome of patients was determined only by treatment and karyotype. Eleven patients have survived, nine in first remission (6 years 5 months to 15 years 2 months), and two are in second remission (3 years 8 months and 8 years 2 months). All ploidy groups are represented in these patients. Late relapses can occur in the hyperdiploid > 50 group, thus accounting for shorter EFS than expected, but because of the unusually long second remission of one patient, the rate of surviving patients was higher for this ploidy group than for all other ploidy groups together. Conversely, patients with only numerical abnormalities (no matter which ploidy group they belonged to), had a better outcome than did patients with structural changes or normal karyotypes and no discrepancy between EFS and survival curves was observed in this chromosomal group. Thus, our results suggest that numerical changes only should be considered an indicator of low risk factor, but our results, based on partially banded karyotypes, need to be verified by a current method and therapy.

Adolescent↗
PubMed1992

Effect of melphalan against self-renewal capacity of leukemic progenitors in acute myeloblastic leukemia.

This study aimed to evaluate the effect of melphalan on both terminal divisions and self-renewal capacity of acute myeloblastic leukemia (AML) progenitors (colony-forming units, CFU-L) grown in methylcellulose. Terminal divisions and self-renewal were assayed by primary (PE1) and secondary (PE2) colony formation, respectively. Thirteen cases of AML, were tested. Melphalan induced a negative exponential dose-effect on CFU-L survival. Moreover, melphalan was equally effective in inhibiting CFU-L growth in both PE1 and PE2 assays, with D10 values of 1.53 +/- 0.17 micrograms/ml and 1.59 +/- 0.21 micrograms/ml for PE1 and PE2, respectively (p = 0.48). Cytotoxicity of melphalan on CFU-L did not differ significantly from that observed for normal hemopoietic granulocyte-macrophage colony-forming units, erythroid burst-forming units, and granulocyte-erythroid-macrophage-megakaryocyte progenitors. Mafosfamide-lysine, a stable cyclophosphamide congener, strongly inhibited primary colony formation (PE1) with a D10 value of 14.46 +/- 1.76 micrograms/ml, but was much less efficient in the PE2 assay. Our findings suggest that the self-renewal capacity of AML progenitors can be differentially affected by alkylating agents. Moreover, since it is now considered that chemotherapy should be preferentially directed against the self-renewal of leukemic progenitors, melphalan might offer a greater potential than cyclophosphamide or cyclophosphamide derivatives in the therapy of AML.

Antineoplastic Agents↗
PubMed1992

[Biological reference values in the human fetus. 106 cord blood sampling in utero].

The authors give biological reference figures obtained from 106 fetuses that were sampled in utero between the 20th and 34th week of amenorrhoea. These fetuses were considered to be normal because there was no clinical or ultrasound evidence of an abnormality. Furthermore the biological values sought in antenatal testing and the absence of all pathology in the first year of life, confirmed that these were normal fetuses. The result has been expressed as a global figure for all 106 fetuses; then they have been divided up according to the gestational age groups (20-23, 24-27, and 28-34 weeks of amenorrhoea). These biological reference values and their changes as the age of the fetuses advanced are discussed and compared with the figures reported in the literature.

Age Factors↗
PubMed1989

Effects of an anti HLA-DR immunotoxin on leukaemia cells and hematopoietic progenitors.

An anti HLA-class II immunotoxin has been prepared by coupling to ricin A-chain (RTA) and anti-DR-DP monoclonal antibody (2G5-MoAb). Protein synthesis inhibition assays showed that 2G5-RTA immunotoxin is: highly cytotoxic to B-cell lymphoid neoplastic cells, and variable so to ALL cells, while AML cell lines display a generally poor susceptibility. Toxicity of 2G5-RTA on normal hematopoietic cells (HPC) was found to be dose-dependent, and to increase significantly with the addition of NH4Cl, used as an activating agent. After 4 h of incubation with 2G5-RTA (10(-8) M), without NH4Cl, percentages of CFU-GM and CFU-GEMM (colony forming units-granulo-monocytes and -multipotent, respectively) progenitor cell recovery were in the order of 50% and 30% respectively. In the same treatment conditions, 2G5-RTA induced a 6 log kill on RAJI cells--measured by clonogenic assay. Finally, this study shows that anti-DR immunotoxins may represent an original, efficient, and relatively safe approach for bone marrow purging of DR positive malignant B-cell populations; while their clinical potential pertaining to ALL and AML remains uncertain.

Animals↗
PubMed1989

Sensitivity of fresh leukemic cells to T101 ricin A-chain immunotoxin: a comparative study between Fab fragment and whole Ig conjugates.

We compared the cell killing potency of a whole Ig ricin A-chain immunotoxin (T101 IgG-RTA) against its Fab fragment counterpart (T101 Fab-RTA) on both CEM cells and fresh malignant lymphoid cells. A dye exclusion assay (DEA), was used to evaluate the kinetics of leukaemia cell viability mediated in vitro by each immunotoxin (IT). This study found that in the absence of ammonium chloride (NH4Cl), used as an enhancer agent, T101 Fab-RTA was significantly more toxic to both CEM and fresh leukaemia cells than T101 IgG-RTA. In the presence of NH4Cl (10(-2) M), while no differences could be found between the two IT on CEM cells, T101 Fab-RTA was clearly superior to T101 IgG-RTA on fresh leukaemia cells. These results suggest that T101 Fab-RTA may offer an excellent alternative to T101 IgG-RTA for IT treatment of CD5 positive leukaemia patients.

Ammonium Chloride↗
PubMed1988

Association of the Philadelphia chromosome and 5q- in secondary blood disorder.

A patient developed a secondary blood disorder 7 years after radiotherapy for a gastric lymphoma. The initial myelodysplastic syndrome evolved to a myeloproliferative phase with transient polycythemia, progressive thrombocythemia, and hyperleukocytosis. Chromosome analysis performed in the terminal phase showed del(5)(q13q31),t(9;22)(q34;q11), and a complex rearrangement involving chromosomes #2 and #3. A correlation between chromosomal abnormalities and hematologic findings could be established. In this case, we have assumed that the Philadelphia translocation is a late event, due to prior mutagen exposure, and its association with a common secondary abnormality (5q-), followed by a progressively developing myeloproliferative phase. Furthermore, the association of Ph and 5q- in a single clone seems to indicate that the same stem cell is affected by these two abnormalities.

Anemia, Refractory, with Excess of Blasts↗
PubMed1987

[Fetal blood sampling under ultrasonic control].

Withdrawing foetal blood from the umbilical cord under ultrasonic control requires close co-ordination between obstetricians and echographists. The most important indications for this procedure are infections and foetal karyotype determination.

Blood Specimen Collection↗
PubMed1987

Rationale for the selection of ricin A-chain anti-T immunotoxins for mature T cell depletion.

A series of 25 different ricin A-chain immunotoxins (IT) were prepared with monoclonal antibodies reacting with several T cell antigens belonging to different clusters of differentiation (CD) to select the most appropriate immunotoxins (IT) for mature T cell depletion. Our screening procedure was performed in 2 steps. First, IT were evaluated using protein synthesis inhibition assay on clonogenic malignant cells in order to determine the most active IT for a given CD. Second, IT thus selected were evaluated for both mature T cell killing efficacy and tolerance on hematopoietic progenitor cells (HPC). This study showed that (1) different IT directed against the same CD antigen displayed a wide range of activity, suggesting the need for a large screening of IT to determine the most appropriate antibody for a given target antigen; (2) anti-CD3 and anti-CD5 ricin A-chain IT are the most active, displaying a cytoreduction of more than 2 logs on mature T cells; (3) the 3 different anti-CD2 ricin A-chain IT evaluated in this study induced poor mature T cell cytoreduction despite their relative efficacy on leukemic cells; (4) anti-CD8 ricin A-chain IT showed almost no efficacy on relevant target cells; (5) no toxicity on HPC was found for concentrations up to 10(-8) of A-chain whatever the IT used.

Antibodies, Monoclonal↗
PubMed1985

Platelet absorption on the test tray (PATT): a rapid method for the screening of HLA class II antibodies using the two-colour fluorescence method.

Several strategies have been proposed for the screening of alloantisera towards HLA class II antigens. Most often the absorption of the sera with platelets is required in order to remove their anti-HLA-A, B, C activity. We have developed a simple micromethod for platelet absorption of sera: platelet absorption on the test tray (PATT); 0.5 microliter of platelet suspension is incubated with 0.5 microliter of the serum to be absorbed in the same tray which is subsequently used for the microlymphocytotoxicity by the two-colour fluorescence method. This technique is proved to be almost as efficient as classical absorption procedures: out of 44 anti-HLA-A, B sera the T-cell activity is completely removed in 43 by a classical procedure as compared to 41 by PATT; only 8% discrepancies were found among 394 reactions. PATT was then used for anti-B lymphocyte screening in 419 anti-HLA-A, B sera; 4% of the sera remained cytotoxic towards T and B lymphocytes while 35% reacted only with B cells, several of them being DR specific. PATT can also be useful for T/B lymphocyte differential cross-matches before kidney transplantation. The method is now routinely used in our laboratory for anti-HLA class II antibody screening.

Absorption↗