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)

The reverse transcriptase-polymerase chain reaction (RT-PCR) has become widely used for monitoring minimal residual disease after allogeneic stem cell transplantation (SCT) for chronic myeloid leukemia (CML). However, most of these studies were performed using qualitative RT-PCR, and the interpretation of the results obtained has been conflicting. The correlation of a quantitative RT-PCR test performed early after SCT (at 3 to 5 months) and long-term outcome of CML patients surviving for more than 6 months was studied. Between January 1991 and June 1999, data from 138 CML patients who received allografts were evaluated. Early RT-PCR results were classified as (1) negative if there were no BCR-ABL transcripts detected (n = 61), (2) positive at low level if the total number of BCR-ABL transcripts was less than 100 per microg RNA and/or the BCR-ABL/ABL ratio was less than 0.02% (n = 14), or (3) positive at high level if transcript levels exceeded the thresholds defined above (n = 63). Three years after SCT the cumulative incidence of relapse was 16.7%, 42.9%, and 86.4%, respectively (P =.0001). The relationship between BCR-ABL transcript level and probability of relapse was apparent whether patients had received sibling or unrelated donor SCT and also whether or not the transplantation was T cell depleted. The results suggest that quantitative RT-PCR performed early after SCT is useful for predicting outcome and may help to define the need for further treatment.
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PMID:Early detection of BCR-ABL transcripts by quantitative reverse transcriptase-polymerase chain reaction predicts outcome after allogeneic stem cell transplantation for chronic myeloid leukemia. 1123 91

The granulocyte-derived hemoregulatory peptide pyroGlu-Glu-Asp-Cys-Lys = pEEDCK is known to keep hematopoietic cells quiescent. When oxidized to its dimeric form (pEEDCK)2, it activates growth of hematopoietic progenitors in association with stroma-derived cytokines. (pEEDCK)2 has a Cys-Cys motif which is also a typical feature of the macrophage inflammatory protein (MIP-1alpha). The present study was designed to analyze differences between the response of normal and leukemic progenitor cells to (pEEDCK)2 or MIP-1alpha. When long-term bone marrow cultures (LTBMCs) were incubated with (pEEDCK)2 or MIP-1alpha and/or cytokines, the stimulatory effect on colony-forming units-granulocyte/erythroid/macrophage/megakaryocyte of LTBMC from chronic myeloid leukemia (CML) patients was less than 50% compared to LTBMC from healthy humans. No difference in oncogene expression could be observed in LTBMC from CML patients regarding reduction of Philadelphia chromosome-associated transcription of the BCR-ABL gene. With respect to the expression of growth and differentiation-associated genes (Galpha16, 5-lipoxygenase, phospholipaseA2, c-kit, and CD34), which were analyzed from LTBMC by semiquantitative reverse transcriptase-polymerase chain reaction, the same transcription rate was observed in CML patients and healthy donors. However, two isoforms of a key enzyme of oxidative metabolism, carnitine palmitoyltransferase (CPT1A and CPT1B), showed 50-fold higher expression rates in LTBMC cells of healthy donors compared to CML patients. It is known that a decrease in oxidative metabolism is associated with an increase in redox equivalents in malignancy. This might result in a reduction of disulphide bonds in (pEEDCK)2 or MIP-1alpha, thus inducing a downregulation of these factors in bone marrow from CML patients.
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PMID:Effect of the hemoregulatory peptide (pEEDCK)2 (pyroGlu-Glu-Asp-Cys-Lys)2 and MIP-1alpha is reduced in bone marrow cultures from patients with chronic myeloid leukemia (CML). 1146 52

This study concerns a patient with minor (m)-BCR/ABL transcript-positive and Philadelphia (Ph) chromosome-negative myelodysplastic syndrome (MDS). The patient was a 78-year-old man whose condition was diagnosed as refractory anemia with excess of blasts in transformation. Molecular genetic studies, using reverse transcriptase polymerase chain reaction analysis detected m-BCR/ABL messenger RNA. We used spectral karyotyping to analyze metaphase cells but could not detect a Ph chromosome. Fluorescence in situ hybridization, however, revealed fusion signals of BCR and ABL probes on an apparently normal chromosome 22.
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PMID:A variant form of myelodysplastic syndrome with Ph- minor-BCR/ABL transcript. 1153 Aug 6

PCR-based monitoring of minimal residual disease (MRD) in acute leukemias can be achieved via detection of fusion gene transcripts of chromosome aberrations or detection of immunoglobulin (Ig) and T cell receptor (TCR) gene rearrangements. We wished to assess whether both PCR targets are complementary in acute myeloid leukemia (AML). We investigated 105 consecutive AML cases for the presence of fusion gene transcripts by reverse transcriptase polymerase chain reaction (RT-PCR): AML1-ETO associated with t(8;21), CBFB-MYH11 with inv(16), PML-RARA with t(15;17), BCR-ABL with t(9;22), and MLL-AF4 with t(4;11). In 17 out of 105 AML cases (16%), fusion gene transcripts were found. Ninety-five of these AML patients (13 with fusion gene transcripts) were also investigated for the presence of IGH, IGK, TCRG and TCRD rearrangements by Southern blot and/or PCR heteroduplex analysis and sequencing. In nine out of 95 patients (9.5%), such rearrangements were found. Combined data revealed that only one patient with a fusion gene transcript had a coexistent Ig/TCR rearrangement. The nine AML patients with Ig/TCR rearrangements, as well as five additional AML patients from a previous study were investigated in more detail, revealing that Ig/TCR rearrangements in AML are immature and unusual. The presence of Ig/TCR rearrangements in AML did not correlate with RAG gene expression levels as determined by real-time quantitative PCR. In conclusion, fusion gene transcripts and Ig/TCR rearrangements are infrequent, but complementary MRD-PCR targets in AML.
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PMID:Fusion gene transcripts and Ig/TCR gene rearrangements are complementary but infrequent targets for PCR-based detection of minimal residual disease in acute myeloid leukemia. 1189 40

Detection of BCR-ABL transcripts in chronic myeloid leukaemia (CML) is used to confirm the diagnosis and to monitor residual disease. Quantitative techniques are required to predict response to therapy or early relapse. We have evaluated an assay in which transcription-mediated amplification (TMA) of BCR-ABL and ABL transcripts is achieved using reverse transcriptase and RNA polymerase. The products are quantified in the hybridisation protection assay (HPA) using acridinium ester-labelled DNA probes and chemiluminescence. The method is a single tube procedure which uses small amounts of RNA (<500 ng/triplicate analysis), is technically simple (requiring just two waterbaths and a luminometer), rapid (total assay time <4 h) and sensitive (capable of detecting one BCR-ABL-positive K562 cell in the presence of 10(4)-10(5) BCR-ABL-negative cells). BCR-ABL signals from patient RNA samples were quantified relative to known amounts of K562 RNA and normalised to levels of ABL. BCR-ABL/ABL ratios ranged from 0.15 to 1.59 (median 0.65) in RNA from diagnostic blood or bone marrow of 18 CML patients and were < or =0.0001 in 20 normal controls. Sequential samples analysed from six CML patients post-allogeneic bone marrow transplantation who relapsed and received donor lymphocyte infusions showed BCR-ABL/ABL ratios which reflected patient status or treatment. A BCR-ABL/ABL ratio of 0.01 served as a useful arbitrary indicator value, with results above and below this value generally correlating with relapse or remission, respectively.
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PMID:Transcription-mediated amplification and hybridisation protection assay to determine BCR-ABL transcript levels in patients with chronic myeloid leukaemia. 1189 44

In many ways, chronic myeloid leukaemia (CML) serves as a paradigm for the utility of molecular methods in the diagnosis of malignancy or for monitoring the response of the patient to therapy. The Philadelphia (Ph) translocation provides an elegant example of how cytogenetic findings provided the starting point for understanding the genetic mechanisms involved in leukaemogenesis. The degree of reduction in tumour load after therapy is an important prognostic factor for CML patients. Several approaches have been introduced that can specifically detect the Ph translocation or its products; these approaches include fluorescent in situ hybridization, Southern blotting, western blotting and reverse transcriptase polymerase chain reaction (RT-PCR). Because non-quantitative RT-PCR analysis after therapy gives only limited information, quantitative or semiquantitative RT-PCR assays have been developed that enable the kinetics of residual BCR-ABL transcripts to be monitored over time in patients after allogeneic stem cell transplantation, interferon-alpha, or STI571 therapy.
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PMID:Minimal residual disease in chronic myeloid leukaemia patients. 1198 22

The reverse transcriptase-polymerase chain reaction (RT-PCR) was compared with fluorescence in situ hybridization (FISH) and real-time quantitative RT-PCR (RQ-PCR) for minimal residual disease (MRD) monitoring in 266 post-transplant bone marrow samples from 78 patients with chronic myelogenous leukemia (CML). The sensitivities of FISH to BCR-ABL positive samples determined by first-round (1st) RT-PCR, second-round (2nd) RT-PCR, and RQ-PCR were 64.2%, 25.8%, and 20.7%, respectively. The BCR-ABL/ABL ratio by RQ-PCR had a mean of 0.000 13 in the 1st RT-PCR-negative samples and 1.42 in the 1st RT-PCR-positive samples (P<0.001), and means of 0.000 39 and 0.51 in the 2nd RT-PCR-negative and -positive samples (P< 0.001). The mean ratios of BCR-ABL/ABL by RQ-PCR were significantly different in N/N (1st/2nd RT-PCR) or N/P and P/P (P<0.001), but not in N/N and N/P, which showed that the discriminative power of RQ-PCR is confined to the 1st RT-PCR level. In this respect, monitoring of the 1st RT-PCR might be useful for estimating normalized BCR-ABL levels after transplantation. Nested RT-PCR was of limited use, as RQ-PCR quantified the BCR-ABL transcripts in 60 (91%) of 66 samples determined to be negative by 2nd RT-PCR. FISH was significantly correlated with RQ-PCR in FISH-positive samples (n=24, r=0.79, P=0.001). An increase of FISH preceded that of RQ-PCR in a few cases with molecular relapse. By analyzing a large number of samples post-transplant, we found that RQ-PCR might be the most useful assay for MRD monitoring; however, FISH and RT-PCR were found to be useful complementary tools.
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PMID:Comprehensive comparison of FISH, RT-PCR, and RQ-PCR for monitoring the BCR-ABL gene after hematopoietic stem cell transplantation in CML. 1214 33

The detection of the Philadelphia (Ph) translocation has been accomplished primarily by cytogenetic analysis and reverse transcriptase polymerase chain reaction (RT-PCR). RT-PCR is highly sensitive (1/10(4)-10(6)) but not quantitatively reliable and is thus unsuitable for the monitoring of Ph-positive cells during therapy. Interphase fluorescence in situ hybridization (iFISH) allows analysis of a large number of cells (> 500) in a timely and efficiently quantitative manner. We obtained 118 peripheral blood (PB) and 127 bone marrow (BM) samples from 75 adult chronic myelogenous leukemia (CML) patients undergoing stem cell transplantation. We simultaneously performed nested RT-PCR and iFISH for all samples. False-positive cells were detected in 2.48% +/- 0.93% (mean +/- SD) of PB samples and 2.75% +/- 0.83% of BM samples. The iFISH results for PB and BM ranged from 1.4% to 92.8% and 1.0% to 93.8%, respectively. Correlation analysis of iFISH results for PB versus BM samples showed a strong relation (r = .993). A significant correlation (P < .05) was also found between iFISH and first-round RT-PCR. The sensitivity of BCR-ABL iFISH was similar to that of first-round RT-PCR, and iFISH results for PB and BM were also well correlated. Thus, iFISH analysis of PB and/or BM samples may be more clinically reliable than RT-PCR in the quantitative monitoring of BCR-ABL fusion in CML after transplantation.
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PMID:Detection of the BCR-ABL gene by interphase fluorescence in situ hybridization (iFISH) in chronic myelogenous leukemia patients after hemopoietic stem cell transplantation: the feasibility of iFISH monitoring of therapeutic response in peripheral blood. 1221 18

From 1994 to 2000, 154 adults with Philadelphia chromosome-positive (Ph(+)) and/or BCR-ABL(+) acute lymphoblastic leukemia (ALL) were treated according to a prospective trial (median follow-up, 4.5 years) with the aim to study the prognostic value of early response to therapy and the role of stem cell transplantation (SCT) in first complete remission (CR). All patients received a standard induction course followed by a course of mitoxantrone and intermediate-dose cytarabine (HAM). After each course, minimal residual disease was tested by specific reverse transcriptase-polymerase chain reaction (RT-PCR) (median sensitivity, 10(-5)). Allogeneic SCT (if a donor) or autologous SCT (if not) was planned at 3 months in all patients in CR after HAM. CR rates after induction, after HAM, and at 3 months were 53%, 67%, and 62%, respectively. High leukocyte count and m-bcr subtype were the 2 identified bad-prognosis factors for CR at 3 months, both superseded by a poor early response assessed at day 8 of the induction course. HAM-associated salvage rate was higher in patients with M-bcr than in those with m-bcr ALL (55% vs 30%; P =.05). In the 103 patients eligible for SCT, the existence of a donor and the negative BCR-ABL status after HAM were independently predictive of remission duration (P <.001 and.01, respectively) and survival (P =.02 and.01, respectively). Relapse was the most common cause of treatment failure in all patient groups. Allogeneic SCT in first CR is the current best treatment option in adults with the disease. New strategies must be tested during early phases of therapy to increase the rate of BCR-ABL(-) remissions.
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PMID:Outcome of treatment in adults with Philadelphia chromosome-positive acute lymphoblastic leukemia--results of the prospective multicenter LALA-94 trial. 1223 43

The kinetics of minimal residual disease (MRD) and chimerism were studied in 15 patients with chronic myeloid leukemia (CML) receiving nonmyeloablative stem cell transplantation (NST) and in 10 patients receiving conventional stem cell transplantation (CST). All NST patients showed T-cell mixed chimerism (MC) while granulocyte and B-cell MC occurred in 80% and 60% of the NST patients, respectively. In CST patients, T-cell MC was detected in 5 patients, of whom 3 were mixed only during the first month. MRD was detected in all NST patients. During the first 3 months the median BCR-ABL/ABL ratio was 0.2% in NST patients compared with 0.01% in CST patients (P <.01). However, 12 months after transplantation, the percentage of reverse transcriptase-polymerase chain reaction (RT-PCR)-positive patients was 20% in NST patients and 50% in CST patients. In conclusion, molecular remission can be induced in most patients after NST, albeit with different kinetics from CST.
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PMID:Kinetics of minimal residual disease and chimerism in patients with chronic myeloid leukemia after nonmyeloablative conditioning and allogeneic stem cell transplantation. 1239 98


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