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M Lübbert

Publications and source records attributed to M Lübbert.

At least 55 records · Page 3Linked to original sources
PubMed1998

Detection of karyotypic aberrations in acute myeloblastic leukaemia: a prospective comparison between PCR/FISH and standard cytogenetics in 140 patients with de novo AML.

In 140 patients with de novo acute myeloid leukaemia (AML) standard cytogenetics were compared with RT-PCR for the detection of t(8;21), t(15;17) and inv(16) and fluorescence in situ hybridization (FISH) for numerical aberrations of chromosomes 7, 8, X and Y. RT-PCR detected 18 cases with t(8;21), 12 with t(15;17) and seven with inv(16). In two cases with t(8;21), two with t(15;17) and four with inv(16) these aberrations had not been detected by standard cytogenetics. There were no false negative PCR results. In 12 patients with these chromosomal changes, standard cytogenetics revealed additional chromosomal aberrations. In 16 patients sole numerical aberrations of the chromosomes 7, 8, X or Y were found by FISH. In these patients the sensitivity of FISH and standard cytogenetics was comparable. In 87 patients no aberrations could be found by PCR and FISH whereas in 24 of these patients standard cytogenetics revealed an abnormal karyotype. These data recommend the combination of standard cytogenetics and molecular techniques to improve the sensitivity for the detection of genetic lesions in AML. Once chromosomal markers have been identified by combined analysis these markers could be used to monitor residual disease during/after chemotherapy, by RT-PCR and/or FISH.

Adult↗
PubMed1997

Acute myelomonocytic leukemia secondary to synchronous carcinomas of the breast and lung, and to metachronous renal cell carcinoma.

We describe a patient in whom synchronous breast cancer and small-cell lung cancer, and metachronous renal cell carcinoma were diagnosed within an 11 months period. All three tumors were treated surgically, followed by administration of tamoxifen, adjuvant chemotherapy with etoposide (2.8 g/m2 total) and vindesine, and administration of interferon alpha and flutamide. The patient developed acute myelomonocytic leukemia 26 months after discontinuation of etoposide-containing chemotherapy. This pattern of multiple neoplasms fits the wider disease spectrum associated with germline mutations of the p53 gene; however, analysis of p53 exons 5-8 did not disclose any sequence abnormalities in this patient. In conclusion, clustering of four (synchronous and metachronous) malignancies may on rare occasions occur in an individual patient and in the absence of a family history of cancer; the sequence during which treatment of primary malignancies may result in treatment-related acute myelocytic leukemia is discussed.

Breast Neoplasms↗
PubMed1997

Treatment of relapsed non-Hodgkin's lymphoma after BEAM chemotherapy and autologous transplantation by BU/CY chemotherapy and salvage transplantation.

We report a patient with centroblastic non-Hodgkin's MALT lymphoma of the stomach treated initially with surgery and post-operative chemotherapy and radiotherapy. First relapse was treated with high-dose BEAM chemotherapy and autologous peripheral blood stem cell transplantation (PBSCT). Second, systemic relapse was treated with high-dose BU/CY and second PBSCT. Today, the patient is in complete remission at 27+ months. The case indicates a curative potential for high-dose BU/CY chemotherapy as salvage therapy for relapsed high-grade lymphoma after BEAM and autologous PBSCT. This may have implications for the prevention as well as for the management of lymphoma relapse after high-dose chemotherapy (HDC) and autologous PBSCT.

Adult↗
PubMed1997

The human lysozyme gene undergoes stepwise demethylation during phagocyte maturation.

The lysozyme (LZM) gene provides a very useful model for studies of phagocyte maturation, because its protein synthesis is increased during myelopoiesis and thus most abundant in terminally differentiated and activated phagoyctes. LZM gene expression and DNA methylation were examined in various normal and transformed hematopoietic cells. Two shifts toward LZM gene demethylation coincided with upregulation of expression: activation of expression in myeloid precursor cells was associated with significant demethylation at a CpG dinucleotide within an Alu repeat in the 5' flanking region; high-level expression in different types of mature phagocytic cells was associated with complete demethylation at two additional, intragenic CpG sites contained in Alu sequences. The possibility that methylation changes occurring within the 5' region of the human lysozyme gene could be involved in the transcription of this gene is discussed, as well as a possible role for demethylation in the maintenance of distinct maturation stages during phagocyte development.

Cell Differentiation↗
PubMed1997

Successful treatment of disseminated central nervous aspergillosis in a patient with acute myeloblastic leukemia.

Invasive opportunistic mycoses are common complications in patients suffering from hematological disorders. Brain abscesses in the immunocompromised host are known to be most frequently caused by fungi of the Aspergillus species and are often associated with concomitant pulmonary disease. As the penetration of the currently available antifungal agents into the brain tissue is limited, only very few patients have been described to survive this life-threatening condition. We report the case of a 62 year old female patient who presented with multiple aspergillus brain abscesses during prolonged neutropenia following induction chemotherapy for acute myeloblastic leukemia and was successfully treated with high dose (8 mg/kg/day) liposomal amphotericin B.

Amphotericin B↗
PubMed1997

Cytosine methylation changes during normal hematopoiesis and in acute myeloid leukemia.

The possible role of DNA methylation changes during several commitment steps of immature myeloid precursor cells toward functional, terminally differentiated phagocyte cells has previously been examined in the human myeloperoxidase (MPO) and macrophage colony-stimulating factor/c-fms genes using normal and transformed myeloid precursor cells. The human lysozyme (LZM) gene also provides a very useful model, because its protein synthesis is continuously increased during myelopoiesis and thus most abundant in mature phagocytes. Several shifts toward LZM gene demethylation coincide with upregulation of expression: activation of expression in myeloid precursor cells and in primary cells of acute myeloid leukemia (AML) was associated with demethylation at a CpG dinucleotide within the 5' flanking region; high-level expression in different types of normal mature phagocytic cells was associated with complete demethylation at two additional, intragenic CpG sites. Methylation changes occurring within the lysozyme gene could reflect transcriptional control of gene expression or maintenance of distinct maturation stages during phagocyte development. They correlate with maturational arrest and lysozyme gene expression in acute myeloid leukemias and may thus provide a genetic marker for the blocked differentiation of these neoplastic cells. Similar observations have been made for the MPO and c-fms genes.

Cytosine↗
PubMed1996

Developmental regulation of myeloid gene expression and demethylation during ex vivo culture of peripheral blood progenitor cells.

Expression of tissue- and development-specific genes is coordinately regulated during maturation of hematopoietic precursor cells toward functional, end-stage peripheral blood (PB) cells. To study the expression and methylation of several myeloid-specific genes during in vitro differentiation of normal hematopoietic progenitor cells, we used a model of CD34+ selected PB progenitor cells (PBPCs). PBPCs from six patients with solid tumors were recruited by standard-dose chemotherapy and subsequent administration of recombinant granulocyte colony-stimulating factor (G-CSF). PBPCs were collected and CD34+ cells selected by immunoadsorption columns using a biotinylated anti-CD34 monoclonal antibody. Enriched cells contained between 78% and 90% (median, 84%) CD34+ cells as determined by fluorescence-activated cell sorting analysis. Cell preparations were cultured in the presence of interleukin-1 beta (IL-1 beta), IL-3, IL-6 and stem cell factor and with or without G-CSF for various time intervals up to 20 days. Genes for CD34 surface antigen, lysozyme (LZM) and myeloperoxidase (MPO) were examined by RNA and DNA analyses. A rapid and early downregulation of CD34 transcripts was observed, with concomitant, time-dependent upregulation of expression of both the LZM and MPO genes. These effects were enhanced in the presence of G-CSF. Analysis of the DNA methylation status at key sites within these genes showed a pattern of differentiation- and expression-associated demethylation of the LZM gene, which was also enhanced by G-CSF, and constitutive and unaltered demethylation at key regions of the CD34 and MPO genes. In conclusion, the genes for CD34, LZM, and MPO are regulated during in vitro culture of very immature PBPCs in the presence of stem cell factor, IL-1, IL-3, IL-6; their effects are enhanced by G-CSF.

Antigens, CD34↗
PubMed1996

HTLV-I-associated adult T cell leukemia/lymphoma in two patients from Bucharest, Romania.

Two middle-aged patients with T cell lymphoma, both natives of Bucharest, Romania, tested positive for HTLV-I antibodies. Malignant cells had the typical phenotype and morphology of adult T cell leukemia/lymphoma (ATL). Both cases presented with extranodal manifestation, hypercalcemia, early recurrence after initial responses to therapy, and subsequent resistance to conventional and intensified chemotherapy. Infection with HTLV-I was confirmed by PCR analyses of serial biopsies. Neither patient reported known risk factors for HTLV-I infection. This report points to the possibility that Romania may represent an endemic area for HTLV-I and should heighten the awareness towards HTLV-I infections in Romanian patients.

Adult↗
PubMed1995

Expression of the Fas antigen on primary human leukemia cells.

The antigen defined by the monoclonal antibody anti-Fas can mediate apoptosis, is associated with the receptor for tumor necrosis factor, and is expressed on a limited number of human tissues. In this study we analyzed the expression of Fas on primary human leukemic cells and on mononuclear cells from other hematologic disorders. A total of 95 samples of blood or bone marrow were studied by indirect immunofluorescence. These samples included the normal controls, 47 cases of acute myelogenous leukemia (AML), 11 cases of acute lymphoblastic leukemia (ALL), 21 cases of leukemic lymphoma, seven cases of chronic myelogenous leukemia (CML), five cases of plasma cell leukemia or multiple myeloma, and five cases of myelodysplastic or myeloproliferative syndromes. Normal controls were negative without exception. Among AML, 13/47 cases (28%) were positive; among ALL, 1/11 cases (9%) was positive; among leukemic lymphomas, 3/21 cases (14%) were positive. In a case of plasma cell leukemia which strongly expressed the Fas antigen, we demonstrated that the antibody mediates cell lysis, which was synergistically enhanced by the addition of rabbit complement. In patients with AML, Fas positivity had no obvious clinical relevance. Taken together, our results show that approximately 30% of cases of AML and occasionally other leukemias express the Fas antigens, whereas normal controls are negative in our test system. These findings may be useful in the treatment of refractory leukemias or may permit the purging of autologous transplants.

Antigens, Surface↗
PubMed1995

Modulation of vindesine and doxorubicin resistance in multidrug-resistant pleural mesothelioma cells by tumor necrosis factor-alpha.

Tumor necrosis factor-alpha (TNF-alpha) has been shown to enhance the cytotoxicity of a variety of antineoplastic agents. To examine whether multidrug-resistant cells are targets of TNF-alpha, and whether TNF-alpha is capable of modulating chemoresistance of these cells, a pleural mesothelioma cell line (PXF1118L) and two multidrug-resistant sublines thereof were used as experimental models. Drug resistance of these cells was due to P-glycoprotein expression, as confirmed by (1) staining with a monoclonal antibody (MRK16) specific for human P-glycoprotein, (2) decreased accumulation of [3H]vinblastine that was reversed by verapamil, and (3) enhanced cytotoxicity of vindesine in the presence of verapamil. Parental and multidrug-resistant cells exhibited little but comparable sensitivity to TNF-alpha alone. Combining TNF-alpha with vindesine or, to a lesser extent, with doxorubicin, but not with cisplatin, resulted in greater cytotoxicity towards multidrug-resistant cells than seen for each compound alone, indicating a synergism. In contrast, TNF-alpha failed to modulate vindesine or doxorubicin cytotoxicity in parental cells. [3H]Vinblastine accumulation was unaffected by TNF-alpha, and chemoresistance was reduced by TNF-alpha also in the presence of verapamil (10 microM), indicating that TNF-alpha was acting in a way different from calcium-channel blockers. Though the molecular mechanism by which TNF-alpha was enhancing vindesine and doxorubicin cytotoxicity remained undefined in this study, the numbers of TNF-alpha binding sites on parental and on multidrug-resistant cells were similar, and P-glycoprotein expression was unmodulated during the entire 48 h incubation period. In conclusion, we show that TNF-alpha increases the cytotoxicity of anticancer drugs in multidrug-resistant tumor cells by a mechanism that differs from most chemosensitizing agents, including verapamil. Further studies will be needed to clarify the mechanism by which TNF-alpha synergizes with anticancer drugs.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1994

Mechanisms of p53 alteration in acute leukemias.

Disruption of normal p53 expression is the most frequent genetic change occurring in various human solid tumors; it is mostly due to sequence alterations of the p53 coding region by missense mutations or to loss of an entire, functional allele of this gene. In the present study, possible mechanisms resulting in a disruption of regulated expression of wild-type p53 were examined in acute leukemias of either lymphoid (ALL) or myeloid (AML) phenotype. p53 transcript accumulation, nucleotide sequence and gene structure were analyzed in primary leukemic cells from 50 patients. p53-specific transcripts were detected in 26/26 cases of ALL and 16/23 cases of AML using reverse transcriptase (RT)-PCR. Sequencing of transcripts did not reveal any point mutations or deletions. Heterozygosity at a polymorphic Bg/II site within intron 1 was found in 4/28 leukemic samples, and loss of one allele was noted in one of these. In addition, a novel, leukemia-associated structural abnormality located within the 5' flanking region of the p53 gene and associated with the loss of heterozygosity was observed in cells from this patient with ALL. The MDM2 gene which inactivates p53 by binding to it was neither amplified nor rearranged in 28 leukemias studied. Thus, disruption of regulated p53 expression resulting in lack of detectable p53 mRNA even by RT-PCR occurs in about 30% of cases of AML; however, p53 alterations typical for human solid tumors are an infrequent event in most types of human acute leukemias.

Acute Disease↗
PubMed1993

N-ras mutations are associated with poor prognosis and increased risk of leukemia in myelodysplastic syndrome.

To evaluate the clinical significance of N-ras mutations in the myelodysplastic syndrome (MDS) archival bone marrow samples from 252 patients were studied for the presence of N-ras exon I mutations using polymerase chain reaction amplification and differential oligonucleotide hybridization. Subsequently, clinical information about these patients was obtained and analyzed. Of 220 evaluable patients, 20 (9%) had point mutation of N-ras involving codon 12. Individuals with N-ras mutation had a significantly shorter survival period than those who were N-ras negative (P = .02). An increased risk of acute myelogenous leukemia (AML) was also found in patients with N-ras mutations (P = .005). N-ras mutations were not associated with any French-American-British (FAB) subtype, with the presence of increased myeloblasts, or with chromosomal aberrations in the bone marrow. However, the presence of increased bone marrow blasts was strongly associated with poor survival rate and risk of AML (P < .001 for each). After stratifying for the percentage of blasts, N-ras mutations remained significantly associated with shorter survival period (P = .04) and increased risk of AML (P = .02). Bone marrow cytogenetic abnormalities, particularly when multiple abnormalities were present, were significantly associated with a poor prognosis (P < .001). In conclusion, N-ras mutation, although relatively infrequent in MDS, is associated with short survival period and increased probability of developing AML.

Bone Marrow↗
PubMed1993

N-RAS gene activation in acute myeloid leukemia: association with expression of interleukin-6.

The 21 kDa proteins encoded by RAS genes are thought to be involved in intracellular signal transduction. Expression of RAS genes activated by point mutations after transfection into mammalian cells can modulate the response of these cells to exogenously added growth factors and their expression patterns of growth factors. We analyzed leukemic cells from 50 patients with acute myeloid leukemia (AML) for the presence of activating point mutations of the N-RAS gene using polymerase chain reaction (PCR) and differential oligonucleotide hybridization. This assay allows semiquantitative determination of the relative abundance of cells carrying N-RAS mutations. Clonal activation of N-RAS, noted in the large majority of leukemic cells of the six of these patients, was correlated significantly (p = 0.0003) with the ability of these cells to express interleukin 6 (IL-6), previously shown to be expressed at high levels in approximately 30% of primary AML cells. In 16 patients, the presence of N-RAS mutations was observed only in subpopulations of leukemic cells. The 'subclonal' involvement of some but not all leukemic cells was further demonstrated by PCR analysis of individual clones grown in soft agar culture. We investigated whether additional, complementary changes in oncogene structure occurred in cells exhibiting clonal activation of N-RAS. For instance, concomitant activation of N-RAS and amplification or rearrangement of c-MYC have been observed in various tumor tissues. Southern blot analysis did not, however, reveal gross alternations of MYC gene structure or copy number in these cells.

Base Sequence↗
PubMed1992

A switch toward demethylation is associated with the expression of myeloperoxidase in acute myeloblastic and promyelocytic leukemias.

Expression of numerous genes encoding myeloid-specific proteins is tightly regulated during normal myeloid differentiation. This heterogeneous group of genes thus offers a tool for dissection of different maturational steps of myelopoiesis. We have previously shown that the human myeloperoxidase (MPO) gene is modified at numerous CpG residues in normal myeloid cells and in myeloid cell lines in a development-specific and expression-associated manner. In the present work, we have applied this type of methylation analysis to primary leukemia myeloid cell samples. We found that expression of MPO messenger RNA (mRNA) is grossly limited to leukemias of late myeloblastic and promyelocytic stages; expression is thus associated with progressive demethylation in the 5' region of the MPO gene. This modification was not global. Low-level induction of MPO mRNA expression in very immature leukemic cells using phorbol ester was not accompanied by progressive demethylation. This type of methylation analysis of a myeloid-specific gene may yield a molecular indicator for different types of myeloid leukemias.

Blotting, Northern↗
PubMed1992

Clonal analysis of bcr-abl rearrangement in T lymphocytes from patients with chronic myelogenous leukemia.

The cytogenetic hallmark of chronic myelogenous leukemia (CML) is the Philadelphia chromosome (Ph1), which reflects a chromosomal translocation t(9;22) and a rearrangement of the ABL and bcr genes. This marker is found in all cells arising from the same malignant precursor cell and can be detected in CML cells of the myeloid, monocytic, erythroid, and B-lymphocyte lineage. It is, however, controversial as to whether T lymphocytes of CML patients carry this gene rearrangement. An answer to this question would clarify whether the translocation in CML occurs in a pluripotent hematopoietic stem cell or in a precursor cell already committed to certain lineages, but not the T-cell lineage. To address this question, we established T-cell clones from peripheral venous blood cells of four patients with CML and screened these clones for bcr-abl fusion transcripts by means of polymerase chain reaction and Southern blot analysis. In four T-cell clones of three of these patients, the bcr-abl transcript could be detected. None of 12 T-cell clones of the fourth patient disclosed detectable bcr-abl amplification product. Both CD4+ as well as CD8+ clones displayed fused bcr-abl sequences. These data imply that in CML some but not all T lymphocytes may originate from the Ph1-positive stem cell.

Blotting, Southern↗