Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.7.49 (reverse transcriptase)
31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Serial peripheral blood specimen from eight adult patients after sex-mismatched bone marrow transplantation (BMT) for Chronic Myeloid Leukemia (CML) (N = 3). Ewing sarcoma (N = 1), Acute Myeloid Leukemia (AML) in second remission (N = 1), Acute Lymphoid Leukemia (ALL) (N = 1), of multiple myeloma (N = 2) were analyzed by the simultaneous immunophenotypic (moAbs/ APAAP-staining) and genotypic analysis (for X and Y chromosomes) of interphase cells to characterize mixed chimerism, residual host cells, and leukemic relapse. Although a stable donor chimerism for T cells, myelomonocytic cells, and granulocytes was developed in seven of the eight patients at Days +21 to +28 post BMT, 0.5 to 1% host cells of different lineages remained continuously in five of the eight patients post BMT (> day 100). In two patients, one with common ALL and the other with multiple myeloma and long-term stable mixed chimerism, a tumor cell relapse was detected first in a sample at Day +176 and confirmed at Day +294. These malignant cells were genotypically of host origin and presented phenotypes identical to those at diagnosis. In the three patients with CML, residual host cells were identified as CD13 (Patient 3) of CD13/CD34 (Patient 4) positive and in one case as CD4/CD8 positive (Patient 7). Since no exclusive antigenic marker is available for this discrimination in these CML patients, normal host hematopoiesis can interfere with the identification of residual disease. Therefore, the identification of the bcr-abl transcripts by a two-step reverse transcriptase-polymerase chain reaction (RT-PCR) was included in this analysis. Patient 3 was bcr-abl positive at [Days +21, +28, +35, and +311, but negative at Days +121 and +400; Patient 4 was bcr-abl positive at only Day +166 post BMT. These results are interpreted as signaling a continuing risk of relapse. In Patient 7, the bcr-abl RT-PCR was negative at Days +142, +166, and +237. Thus, the combination of the simultaneous immunophenotypic and genotypic analysis and the bcr-abl detection by RT-PCR clearly improves the discrimination between malignant cells and normal residual host cells.
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PMID:Qualitative assessment of mixed chimerism after allogeneic bone marrow transplantation with regard to leukemic relapse. 893 46

Chronic myeloid leukemia (CML) is a myeloproliferative disorder characterized by the presence of a reciprocal translocation between chromosomes 9 and 22 in at least 95% of cases. At the molecular level, this translocation results in the activation of the ABL oncogene of chromosome 9, which becomes contiguous with the 5' end of the BCR gene on chromosome 22. The breakpoint usually occurs between exons 2 and 3 (b2-a2 rearrangement), or 3 and 4 (b3-12 rearrangement) of the major breakpoint cluster region (M-BCR) of the BCR gene. The aim of the present study was to characterize the type of BCR-ABL transcript in 32 patients with CML using the reverse transcriptase-polymerase chain reaction (RT-PCR) and to determine if this type of rearrangement is related to the survival of the patients. Our results confirmed that RT-PCR is more sensitive than cytogenetic analysis for identifying the Philadelphia (Ph1) chromosome (96.9% vs 79.3%). The frequencies of b2-a2 and b3-a2 rearrangements were 28.1% and 65.7%, respectively. The survival of patients presenting the b2-a2 or the b3-a2 rearrangement was not significantly different (P = 0.27750). The data suggest that the type of transcript has no prognostic value for CML patients.
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PMID:Prognostic significance of BCR-ABL rearrangement in chronic myeloid leukemia. 918 Nov 1

The t(9;22)(q34;q1 1) between the abl and bcr genes plays a pivotal role in the diagnosis and pathogenesis of chronic myelogenous leukemia (CML). Its detection is routinely accomplished by Southern blot analysis and karyotyping. Interphase fluorescence in situ hybridization (FISH) and reverse transcriptase-polymerase chain reaction (RT-PCR) are emerging molecular techniques that offer viable alternatives. We analyzed 40 samples of peripheral blood and bone marrow (CML, 16; acute myelogenous leukemia, 6; acute lymphoblastic leukemia [ALL], 1; chronic lymphoblastic leukemia, 2; myelodysplasias, 4; myeloproliferative disorders, unclassified, 3; nonleukemic hematologic malignancies, 3; hypercellular bone marrow, 1; normal control samples, 2; and K562 cell line samples, 2) for the presence of bcr-abl fusion gene and its messenger RNA (mRNA) transcript by FISH and RT-PCR, respectively. We compared the results with results of Southern blot analysis and karyotyping when available. Cost analysis was performed. Thirty-three samples were evaluable by FISH; 14 of 14 evaluable CML samples and one ALL sample were positive for bcr-abl by FISH (100%). The other 15 evaluable samples were negative; 16 of 16 (100%) and 13 of 16 (81%) of CML cases were positive for bcr-abl mRNA by RT-PCR (chemiluminescent blot method) and RT-PCR (colorimetric method), respectively. The ALL sample was positive by both RT-PCR methods. All other samples were negative by RT-PCR (chemiluminescent blot method), and all but 1 case of myeloproliferative disorder tested negative by RT-PCR (colorimetric method). We conclude the utility of FISH and RT-PCR is associated with certain limitations, such as insufficient RNA for RT-PCR and the occasional absence of internal positive FISH control signals. However, each procedure offers (with a high concordance rate) a specific and cost-effective alternative to Southern blot analysis and karyotyping and improved turnaround time for the detection of bcr-abl fusion gene or its mRNA transcript.
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PMID:Comparative analysis of interphase FISH and RT-PCR to detect bcr-abl translocation in chronic myelogenous leukemia and related disorders. 942 10

A 48-year-old patient was admitted to our hospital for leukocytosis. The blast cells were positive for peroxidase and he was tentatively diagnosed as acute myeloid leukemia according to the French-American-British criteria. By flow cytometry, the bone marrow cells were positive for CD10, CD13, CD33 and HLA-DR, but two-color analysis revealed that most of the CD13- and CD33-positive cells did not express CD10. The marrow cells had Philadelphia chromosome with no additional abnormalities. Major bcr-abl fusion gene was observed by the reverse transcriptase-polymerase chain reaction method. Southern blot analysis disclosed rearrangement of both immunoglobulin heavy chain and T-cell receptor beta chain genes. He received combined chemotherapy for myeloid lineage and lymphoid lineage, but the response was quite poor. He died 64 days after admission due to pulmonary bleeding. Although the association of Ph1 with multilineage differentiation is unclear, our case has significant implication for further investigation of the relationship between Ph1-positive cells and lineage selection.
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PMID:Dual rearrangement of immunoglobulin and T-cell receptor genes in a case of Philadelphia chromosome-positive acute leukemia. 973 Jan 56

Little is known about the mechanisms and the kinetics of the so-called graft-versus-leukemia (GVL) response induced by donor lymphocyte infusions (DLI) in patients with leukemic relapse after allogeneic bone marrow transplantation (BMT). We sought to elucidate this problem by sequentially studying three patients with relapsed chronic myeloid leukemia after sex-mismatched BMT from time before donor leukocyte infusion until achievement of complete molecular remission. Lineage-specific chimerism was assessed longitudinally by a combined fluorescent immunophenotyping and sex chromosome-specific in situ hybridization approach. Results were related to quantitative detection of bcr-abl transcripts by competitive differential reverse transcriptase-polymerase chain reaction (RT-PCR), qualitative bcr-abl RT-PCR, and multiplex PCR-based DNA donor/recipient chimerism. All patients had predominant donor lymphopoiesis at the time of DLI, suggesting a state of tolerance to recipient leukemic and/or normal cells. In contrast, granulopoiesis and erythropoiesis were mainly recipient derived in both patients with hematologic relapse and partly recipient derived in the patient with molecular relapse. Eighty percent, 90%, and 8% of CD34(+) cells, respectively, were found to be of recipient origin at relapse, and few donor stem cells predicted for cytopenia post-DLI. Responses were seen after a time lag of 5 to 13 weeks after DLI and resulted in reversal to full donor chimerism within a critical switch period of 4 to 5 weeks. A sudden decrease in recipient cells was paralleled by a sharp decrease in bcr-abl transcript numbers detectable several weeks before achievement of molecular remission and onset of clinical graft-versus-host disease (GVHD). This response pattern was confirmed by retrospective RT-PCR analysis in an additional five patients. Prospective monitoring of stem cell chimerism and response may enable us to individually tailor adoptive immunotherapy in the future.
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PMID:Kinetics of the graft-versus-leukemia response after donor leukocyte infusions for relapsed chronic myeloid leukemia after allogeneic bone marrow transplantation. 1023 94

To investigate the potential of autologous lymphocytes to eliminate chronic myelogenous leukemia (CML) cells following activation and targeting by CD3-monoclonal antibody, we cultured Ficoll-isolated peripheral blood cells from 11 patients with CML in the chronic phase in permutated combinations of interleukin (IL)-2, CD3-monoclonal antibody (OKT3), and interferon (IFN)gamma. The efficiency of CML cell elimination was studied by means of flow cytometry and reverse transcriptase-polymerase chain reaction (RT-PCR) analysis. Cultures containing only OKT3 and IL-2, with or without IFNgamma, resulted in tumor cell reduction to the level of RT-PCR negativity. The length of the culture period required to reach a RT-PCR-negative state ranged from 3 to 33 days. A 1- to 2-log reduction in leukemic cells could be achieved by culture medium alone. In contrast, 3- to 4-log reductions in CML cells were observed following in vitro culture and ex vivo T cell activation with a given sensitivity for RT-PCR detection of 1 bcr/abl+ cell in 10(4). The feasibility of purging chronic myelogenous leukemia cells in a short time was associated with a low number of platelet counts (r=0.6457; p < 0.05). CML cell reduction was associated with expansion of CD25+/CD4+//CD8+/-/CD56+/- lymphocytes. These findings may be of relevance for immunotherapy procedures.
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PMID:Activation of autologous lymphocytes of patients with chronic myelogenous leukemia in the chronic phase with cytokines and CD3 monoclonal antibody results in bcr/abl- blood leukocyte cultures as determined by reverse transcriptase-polymerase chain reaction. 984 83

Reciprocal translocations involving the MLL gene on chromosome band 11q23 have been observed in both acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL). In AML, identification of MLL breakpoints is an important prognostic factor. Breakpoints are clustered in an 8 kb DNA fragment (bcr) and can be detected by Southern blotting or fluorescence in situ hybridization (FISH) analysis. Our objective in this study was to design a DNA probe set that enables optimal detection of MLL rearrangements using interphase FISH. Two PAC clones, 217A21 and 167K13, spanning the MLL gene with a minimal overlap in the bcr were isolated and labeled. Twenty-seven AML/ALL patients with cytogenetic 11q23 abnormalities, seven AML/ALL patients without 11q23 abnormalities but MLL rearrangement by Southern blotting, and eight healthy donors were analyzed by FISH. We compared this double-color FISH analysis with FISH using a YAC clone (yB22B2) and with Southern blotting. The PAC probe combination detects an MLL breakpoint in all cases with MLL rearrangement detected by Southern blotting except for cases with a partial tandem duplication detected by reverse transcriptase-polymerase chain reaction (RT-PCR). FISH using the PAC probes also detected MLL breakpoints in four cases with MLL deletions telomeric to the breakpoint that could not be detected by the single probe yB22B2. This new probe set provides a reliable and rapid assay for the diagnosis of AML and ALL patients with MLL/11q23 breakpoints.
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PMID:A DNA probe combination for improved detection of MLL/11q23 breakpoints by double-color interphase-FISH in acute leukemias. 1073 98

The Philadelphia (Ph) chromosome is observed in approximately 1% of patients with acute myeloblastic leukaemia (AML), especially subtypes M1 and M2 in the French-American-British classification. We describe here a cytogenetic and molecular investigation of a rare case with Ph-positive AML M6 (erythroleukaemia). A 63-yr-old woman was diagnosed as having erythroleukaemia. Leukaemic cells were positive for CD4 and CD7 as well as CD13, CD33, CD34 and HLA-DR. They were analyzed by G-banding, fluorescence in situ hybridization (FISH), Southern blot and reverse transcriptase polymerase chain reaction analyses. The karyotypes at diagnosis were as follows: 61, XX, -X, -1, -2, -3, -4, -5, -7, t(9;22)(q34;q11)x 2, -15, -16, -17, -18, + 19, +21, +22 [3]/61, idem, -22, +der(22)t(9;22) [36]. FISH with BCR/ABL probes showed that 39% and 57% of interphase nuclei had double and triple BCR/ABL fusion signals, respectively. Chromosome analysis in complete remission showed a normal karyotype in all 20 metaphases, confirming the diagnosis as Ph positive-acute leukaemia. FISH at relapse showed that 92% of interphase nuclei had triple fusion signals. Rearrangement of major breakpoint cluster region (M-bcr) in the BCR gene and coexpression of p210-type (b2a2) and p190-type (e1a2) BCR/ABL fusion transcripts due to alternative splicing were also detected. We conclude that clonal evolution from double to triple Ph chromosomes may be implicated in the disease progression. Considering other two reported cases, Ph-positive erythroleukaemia appears to be correlated with coexpression of myeloid/T-lymphoid markers and hyperdiploidy with double or triple Ph chromosomes, although breakpoints in the BCR gene are heterogenous.
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PMID:Triple Philadelphia chromosomes with major-bcr rearrangement in hypotriploid erythroleukaemia. 1100 54

Chimera gene products, the molecular hallmark of acute leukemias were detected and quantified for diagnostic purposes and for follow up of therapy and characterization of minimal residual disease. In acute lymphoid leukemia mainly the bcr-abl, and in acute myeloid leukemias, depending on the morphological classification, the aml-eto, bcr-abl, pml-rara, plzf-rara, and cbfb-myh chimeras were investigated. The determinations were based on reverse transcriptase-polymerase chain reaction. The results were used in diagnosis of 315 new leukemic patients, and in follow up of 70 ones. In the present paper the usefulness of the applied methods is illustrated by presentation of data of 38 (27, acute myeloid leukemias and 11 acute lymphoid ones) patients out of the 139 treated in the National Institute during the last years.
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PMID:[Role of molecular genetic investigations in the diagnosis of acute leukemias and in the detection of minimal residual disease]. 1144 38

The bcr-abl chimeric messenger RNA is frequently detected in chronic myeloid leukemia (CML) patients after bone marrow transplantation. It was previously reported that the relapse risk of bcr-abl detection 6 to 12 months after transplantation was greater than 40%. This risk decreased as the time between transplantation and detection increased. To further define the relapse risk associated with bcr-abl molecular detection in "late" CML survivors, 379 consecutive CML patients alive at 18 months after transplantation or later were studied. Ninety of 379 patients (24%) had at least one positive bcr-abl test 18 months after transplantation or later; 13 of 90 bcr-abl-positive patients (14%) and 3 of 289 bcr-abl-negative patients (1.0%) relapsed. The median time from bcr-abl detection to relapse was 916 days (range, 251-2654 days). The hazard ratio of relapse associated with bcr-abl detection was 19.2 (P <.0001). The stage of disease, chronic graft-versus-host disease, and the donor type did not alter the association between bcr-abl and relapse. Quantification of bcr-abl was performed on 344 samples from 85 bcr-abl-positive patients by means of a real-time quantitative reverse transcriptase-polymerase chain reaction assay. The median bcr-abl change of patients who relapsed was significantly greater than those that remained in remission (P =.002). The median bcr-abl level at relapse was 40 443 bcr-abl copies per microg RNA (range, 960-299 552). Of 73 bcr-abl-positive patients who failed to relapse, 69% had only one positive test at a median of 24 copies bcr-abl per microg RNA. The detection of bcr-abl is common following transplantation. The prognostic significance of a qualitative bcr-abl can be refined by quantitative assays and thus may target patients who would benefit from early intervention.
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PMID:The significance of bcr-abl molecular detection in chronic myeloid leukemia patients "late," 18 months or more after transplantation. 1153


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