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Biomedical subjects

J Abels

Publications and source records attributed to J Abels.

At least 37 records · Page 2Linked to original sources
PubMed1989

Uptake of transcobalamin II-bound cobalamin by HL-60 cells: effects of differentiation induction.

Binding and uptake of transcobalamin II-bound cobalamin by HL-60 promyelocytic leukemia cells proceed through receptor-mediated endocytosis. The affinity constant of the receptor for transcobalamin II-cobalamin was found to be 6.1 liter/nmol and the maximal rate of uptake 12 pmol/10(9) cells/h. This uptake is mediated by about 3000 receptor sites per cell. Evidence is presented that the receptor recirculates from the cell surface to the lysosomes and vice versa. Upon differentiation induction of the cells by either DMSO in granulocytic direction or by 1,25-dihydroxy-vitamin D3 in monocytic direction a rapid decline in cellular uptake and cell surface binding of the protein-bound vitamin ensues. In particular the internalization of the complex decreases faster than all other observed signs of the ongoing differentiation process, such as reduction in the OKT9-reactive transferrin receptor, increase in lineage-specific surface markers, and decrease in [3H]thymidine incorporation and actual cell proliferation. The transcobalamin II receptor on the cell surface appears to be a proliferation-associated membrane component in human leukemic cells.

Calcitriol↗
PubMed1989

Nitrous oxide selectively reduces the proliferation of the malignant cells in experimental rat leukemia.

A considerable reduction of hepatosplenomegaly and leucocytosis in leukemic rats of the Brown Norway Myeloid Leukemia (BNML) can be achieved by exposure to 50% nitrous oxide/50% oxygen. In this study the differential antiproliferative effect of nitrous oxide, inactivating vitamin B12, on normal and leukemic hemopoiesis was investigated in this rat model. Rats injected with leukemic cells and exposed to nitrous oxide for 10 days showed 30% reduction of hepatosplenomegaly and 50% reduction of leukocytosis. Similarly treated healthy rats showed no signs of impaired hemopoiesis as measured by peripheral blood parameters. Clonogenic assays of erythroid and myeloid progenitors from both healthy and leukemic rats revealed that exposure to nitrous oxide did not suppress normal bone marrow functioning. On the contrary, the reduction of leukemic proliferation by nitrous oxide retarded the leukemic infiltration of the bone marrow compartment.

Animals↗
PubMed1989

On the value of intensive remission-induction chemotherapy in elderly patients of 65+ years with acute myeloid leukemia: a randomized phase III study of the European Organization for Research and Treatment of Cancer Leukemia Group.

We report the results of a prospective study in patients more than 65 years of age in whom two different therapeutic strategies were compared: immediate intensive-induction chemotherapy (arm A) versus "wait and see" and supportive care and mild cytoreductive chemotherapy only for relief of progressive acute myeloid leukemia (AML)-related symptoms (arm B). The major objective of the study was to compare survival outcome of both regimens. Thirty-one patients on arm A received one or two courses of daunorubicin, vincristine, and cytarabine for remission induction followed by one additional cycle for consolidation in case of complete remission (CR). Among 29 patients on arm B, cytoreductive chemotherapy (hydroxyurea, cytarabine) had to be initiated for palliation of leukemia-associated complications in 21 patients at a median of 9 days after diagnosis. Overall survival duration for patients treated on arm A was significantly (P = .015) longer than the survival in arm B (median survival, 21 weeks v 11 weeks; projected survival at 2.5 years, 13% v 0%). Eighteen (58%) of arm A patients and none (0%) of arm B patients entered CR. Of the first group, projected disease-free survival at 2 years is 17%. The median percentages of days spent in the hospital by arm A and B patients were 55% and 50%, respectively. This study shows that a strategy based on modern supportive care and a wait and see approach yields extremely poor results. It is not superior in regard to the frequency of hospital admission and is inferior regarding survival outcome.

Aged↗
PubMed1989

Alternating v repeated postremission treatment in adult acute myelogenous leukemia: a randomized phase III study (AML6) of the EORTC Leukemia Cooperative Group.

The value of a postremission treatment in acute myelogenous leukemia (AML), with alternating combinations of non-cross-resistant drugs, has been prospectively assessed. Of 515 evaluable patients, 347 (67.4%) entered into complete remission (CR), following induction treatment with daunorubicin (DNR), vincristine (VCR), and cytosine arabinoside (ara-C). After one consolidation course, 248 patients were randomized for six courses of intensive maintenance: either repeated treatment with DNR-VCR-ara-C, or alternating treatment where amsacrine (AMSA) was combined with high dose ara-C on cycle 1,3, and 5 and with 5-azacytidine on cycle 2, 4, and 6. Ninety-nine patients were not randomized: 57 were introduced in a bone marrow transplantation (BMT) program, and 42 went off study, mainly for treatment toxicity or refusal. The main prognostic factors for achievement of CR were performance status, cytogenetics, and age, and for the disease-free survival (DFS): age and number of courses to CR. The rate of second remission was fairly high (64%) for patients relapsing off therapy. The DFS appeared identical (median, 53 weeks), in the two randomized arms, the alternating treatment not showing superiority to the repeated one, in spite of an increased toxicity. The median overall survival for patients achieving a CR was 90 weeks. The reason for the failure of alternating maintenance treatment to improve the DFS is probably related to an insufficient dose intensity: five patients who relapsed during maintenance arm B achieved a second CR with a more intensive combination of high-dose ara-C and AMSA. In addition, 60 patients underwent a BMT (43 allogeneic and 17 autologous). The DFS of patients treated with allogeneic BMT tended to be superior to the one obtained with the chemotherapy program. However the overall survival, as well as the event-free survival, seemed equivalent, including patients who relapsed before the planned BMT. Comparisons between allogeneic BMT, autologous BMT, and intensive consolidation during first CR deserve further prospective studies in AML.

Adolescent↗
PubMed1989

Richter's syndrome with identical immunoglobulin gene rearrangements in the chronic lymphocytic leukemia and the supervening non-Hodgkin lymphoma.

In a patient who developed Richter's syndrome, complex cytogenetic abnormalities of the centroblastic non-Hodgkin lymphoma (NHL) was associated with chemotherapy resistance. The clonal origin of the preexisting chronic lymphocytic leukemia (CLL) and the subsequent NHL cells was investigated. Both cell populations were present in the peripheral blood and could be separated efficiently by counterflow centrifugal elutriation. In the lymph node biopsy mainly NHL centroblasts were found and only a minor population of small lymphocytes. The separated CLL and NHL cells from blood as well as the lymph node cells were found to express mu and kappa Ig chains. Since expression of identical light chains is not synonymous with common clonal origin, Southern blot analysis of the Ig heavy chain genes was also performed, which showed that the two cell populations had identical Ig heavy chain gene rearrangements. Therefore, it was concluded that the CLL cells and the NHL cells in the present case originate from the same precursor cell and that the NHL has to be regarded as a malignant progression of the CLL. These findings are different from our previous report on another patient with Richter's syndrome, in whom the CLL and the NHL represented two unrelated malignancies. Therefore, the occurrence of NHL in Richter's syndrome apparently may represent either a clonal progression of the CLL or a second lymphoid malignancy.

Antigens, Surface↗
PubMed1988

Separation of transcobalamin II isoproteins by means of chromatofocusing.

Transcobalamin II, the principal cobalamin-binding protein in human plasma, expresses a genetic polymorphism. Four more or less common alleles, denoted by X, S, M and F, have been defined earlier by means of gel electrophoretic techniques followed by autoradiography. This technique is less suitable for the analysis of individual samples and requires long exposure times. This paper describes the analysis of transcobalamin II phenotypes by means of fast protein liquid chromatofocusing. This technique has the advantage that the results of the analysis of several samples can be obtained within a day, and it also seems applicable to the preparative separation of transcobalamin II isoproteins. The sequence of elution of the isoproteins was in complete accordance with the banding pattern obtained by electrophoretic separation. The characteristic doublet bands found with polyacrylamide gel electrophoresis were less obvious in the chromatofocusing elution pattern.

Chromatography, Liquid↗
PubMed1988

The reduction of intracellular polyamines by sequential inhibition of the synthesis of decarboxylated S-adenosylmethionine: effects on rat leukemia.

Decarboxylated S-adenosylmethionine (SAM) is an aminopropyl donor in the synthesis of the polyamines, spermidine and spermine. The decarboxylation of SAM is inhibited by the toxic cytostatic drug methylglyoxalbis-(guanylhydrazone) (MGBG). To achieve more specific and less toxic effects of MGBG, this drug was combined with cycloleucine, which inhibits SAM synthesis, and with nitrous oxide, which inhibits methionine synthetase. This treatment thus aimed at sequential inhibition of the synthesis of decarboxylated SAM, and was studied in a rat leukemia model (BNML). Combined treatment further decreased the level of spermine, but not of spermidine, in leukemic cells, compared to the effects of MGBG alone. The therapeutic effects of this combination were additive or less than additive, however. MGBG was not very effective in reducing leukemic growth and severely toxic, although less with combined treatment. Another inhibitor of SAM decarboxylase, berenil, was also used, and although this drug was about equally active in inhibition of leukemic growth, alterations in intracellular polyamines were not observed. The combination of nitrous oxide and cycloleucine, which effectively reduced leukemic growth at non-toxic dosages, selectively inhibited spermine synthesis, and therefore may be used to interfere with polyamine metabolism. The relevance of this polyamine deprivation to the treatment of leukemia could not be demonstrated.

Adenosylmethionine Decarboxylase↗
PubMed1988

Effect of cobalamin inactivation on folate metabolism of leukemic cells.

Exposure to nitrous oxide inactivates the cobalamin coenzyme of methionine synthetase, an essential enzyme in folate metabolism. Hemopoietic cells are especially dependent on the function of cobalamin for the folate-dependent synthesis of thymidylate (dTMP). Inhibition of methionine synthetase may therefore be of potential value in the treatment of hematological malignancies. In the present study we investigated the effect of nitrous oxide induced cobalamin inactivation on folate metabolism of fresh leukemic cells and the human myelomonocytic cell line U937. Cells were exposed to nitrous oxide for 20 h. Subsequently they were subjected to the deoxyuridine suppression test (dU test), which measures the disturbance of folate-dependent dTMP synthesis. In all bone marrow samples, cobalamin inactivation resulted in a 200% increase of the dU test value, implicating a decreased de-novo synthesis of dTMP. Incubation of leukemic cells with methotrexate, 5-fluorouracil or cycloleucine induced similar increases of the dU test values which could be further raised to 400% with the addition of N2O exposure. Prolonged experiments with U937 cells revealed that the disturbance of folate metabolism aggravated up to 48 h of nitrous oxide exposure. It can be concluded that cobalamin inactivation in human leukemic cells results in disturbed folate-dependent dTMP synthesis. Moreover, effects of several drugs interfering with folate metabolism can be enhanced.

Bone Marrow↗
PubMed1988

TdT positive B-cell acute lymphoblastic leukaemia (B-ALL) without Burkitt characteristics.

The leukaemic cells in a 23-year-old man were small to medium-sized lymphoblasts with no cytoplasmic vacuoles and negative with PAS as well with peroxidase and acid phosphatase staining. Cytogenetic analysis showed -6, +12, -22, +mar (6p::22q), resulting in a trisomy 12 and monosomy of the long arm of chromosome 6. Immunological marker analysis revealed that the majority of the blasts was positive for terminal deoxynucleotidyl transferase (TdT) as well as surface membrane immunoglobulin (SmIg, mu, lambda), although B-ALL are supposed to be negative for TdT. The blasts were also positive for HLA-DR, CD9 (BA-2), CD10 (VIL-A1) and CD24 (BA-1), but negative for the B-cell markers CD20 (B1) and Y29/55. Double immunofluorescence staining confirmed that almost all TdT+ cells were also positive for Sm mu, Sm lambda, HLA-DR and CD10. We thus made a diagnosis of TdT+ B-ALL without Burkitt characteristics. Since we could not detect SmIg+/TdT+ cells in bone marrow samples from adult healthy volunteers and from 10 children with ALL in complete remission, we conclude that TdT+ B-ALL cells may not have a normal counterpart in bone marrow or represent a malignant counterpart of a very rare cell in an intermediate differentiation stage between the pre-B-cell and the early B lymphocyte.

Acute Disease↗
PubMed1988

In myelodysplastic syndromes progression to leukemia is directly related to PHA dependency for colony formation and independent of in vitro maturation capacity.

In an agar-liquid double-layer colony assay in which myeloid leukemia colony-forming cells require the presence of both the lectin PHA and CSF for in vitro proliferation, colony formation of bone marrow cells derived from patients with a myelodysplastic syndrome (MDS) was studied. In five of 14 MDS and all five leukemic transformed MDS cases, colony formation was found to require both PHA and CSF. Three of these five PHA-dependent MDS cases progressed to overt leukemia within 1 year, one progressed from RA to RAEB, and one patient received AML chemotherapy. PHA-dependent colony formation was associated with higher bone marrow blast counts, but not directly to FAB type or cytogenetic abnormalities. In nine other MDS cases only CSF was required for colony formation. In these PHA-independent cases the course of the disease was stable during the observation time (5-17 months). Two types of colonies were observed in this in vitro system: colonies adherent and colonies nonadherent to the agar underlayer. The former consisted of terminally differentiated myeloid cells, and the latter comprised immature cells. This suggests that the percentage of adherent colonies formed in vitro may be used as a measure for the maturation defect in MDS. However, no correlation was found between the percentage of adherent colonies and progression to leukemia of the MDS cases. Our findings suggest that the dependency on PHA for in vitro colony formation of colony-forming cells in MDS is predictive for the progression to leukemia. However, the in vitro differentiation capacity has no apparent prognostic significance.

Adolescent↗
PubMed1987

Philadelphia chromosome-positive thrombocythemia and megakaryoblast leukemia.

A case of well-documented and -illustrated megakaryoblastic transformation is described in a patient with thrombocythemia passing through a stage of myelofibrosis without features of chronic granulocytic leukemia. Immunocytologic studies with the use of conventional and monoclonal antibodies against platelet membrane glycoproteins and electron microscopic investigations, demonstrating bull's-eye granules and platelet peroxidase positivity, proved the megakaryocytic differentiation of the blast cells. From the onset of the disease as well as during the megakaryoblastic transformation, the Philadelphia (Ph1) karyotype, 46XX t(9:22) (q34:q11), was found in peripheral blood and bone marrow cells as the only clonal abnormality. Southern blot analysis of DNA extracted from the blast cells revealed a rearrangement within the bcr on chromosome 22 similar to findings in chronic granulocytic leukemia. The presentation with excessive small and abnormal megakaryocytes in the initial and subsequent bone marrow and the rapid progressive myelofibrosis and splenomegaly differentiate the Ph1 chromosome-positive thrombocythemia from the chronic myeloproliferation of thrombocythemia in its primary form or associated with polycythemia vera.

Blood Cells↗
PubMed1987

Antibodies against glycosphingolipids in sera of patients with idiopathic thrombocytopenic purpura.

Evidence is presented for the existence of antibodies against platelet glycosphingolipids in sera of patients with chronic idiopathic thrombocytopenic purpura and antiplatelet antibodies. Increased binding of IgG/IgM to neutral glycosphingolipids or gangliosides extracted from donor platelets was measured by an ELISA in 17 sera of 30 patients. Thirteen sera, five with anticardiolipin antibodies, demonstrated an increased binding to sulphatides confirmed by immuno HPTLC. Four sera showed reactivity with the platelet minor gangliosides established by immuno-HPTLC.

Antibodies↗
PubMed1987

Characterization of the blast cells in acute leukemia with translocation (4;11): report of eight additional cases and of one case with a variant translocation.

Eight new cases (five adults and three children) of acute leukemia characterized by the presence in bone marrow cells of a t(4;11)(q21;q23)and one similar case, a child, with a t(1;11)(p32;q23) are reported. All patients were diagnosed as having acute lymphoblastic leukemia (ALL) with high-risk features. Immunologically the blast cells of the nine cases showed a strikingly consistent immature lymphoid phenotype, i.e., TdT+, HLA-DR+, B4(CD19)+, CALLA(CD10)-, Smlg-, cmu-, BA-2(CD9)+ corresponding to a "null ALL." In addition, six of nine cases expressed the myeloid marker VIM-D5(CD15). By double immunofluorescence staining it was determined that the VIM-D5(CD15) antigen was expressed by terminal deoxynucleotidyl transferase-positive blast cells, excluding the possibility of double leukemia. In five cases investigation of the Ig heavy chain genes by Southern blot analysis showed clonal rearrangement of both Ig heavy chain gene alleles. These data suggest that the blast cells involved in t(4;11) leukemia represent early B-cell progenitors with "aberrant" expression of myelomonocytic features, possibly related to the 11q23 breakpoint.

Adolescent↗