Biomedical subjects

A Gaiger

Publications and source records attributed to A Gaiger.

29 records · Page 2Linked to original sources

PubMed1995

Use of quantitative polymerase chain reaction to monitor residual disease in chronic myelogenous leukemia during treatment with interferon.

Interferon-alpha (IFN-alpha) has become a widely used treatment modality in chronic myelogenous leukemia (CML) and was shown to induce complete hematologic responses in about 70% of the patients. In a minority of cases, complete suppression of the Philadelphia (Ph)-positive clone has been observed by cytogenetic investigation or by Southern blot analysis. In most instances, however, analyses by the highly sensitive two-step polymerase chain reaction (PCR) reveal the presence of residual leukemic cells despite continuous treatment. Since PCR positivity has not been associated with an increased risk of disease recurrence, the monitoring of cells carrying the characteristic BCR/ABL rearrangement by qualitative PCR may not facilitate early identification of patients who are likely to relapse. We have therefore employed a quantitative PCR technique to monitor the BCR/ABL mRNA expression levels during the course of treatment in an attempt to assess the response to IFN-alpha at the molecular level and to provide a basis for early detection of progressive disease. Twenty CML patients who received therapy with IFN-alpha in first chronic phase of the disease were enrolled in the study. In addition, we have monitored two CML patients treated with IFN-alpha for relapse after bone marrow transplantation. Thirteen patients who displayed decreasing, constant or fluctuating levels of BCR/ABL expression during an observation period of up to 4 years (mean 25 months) have remained in hematologic remission. Two patients showed an elevation in the marker gene expression upon discontinuation of treatment, but no further increase in BCR/ABL mRNA has been observed after reinitiation of therapy with IFN, and the patients have remained in hematologic remission. In seven patients, quantitative PCR (Q-PCR) analyses revealed increasing expression of the chimeric gene during treatment with IFN-alpha. In all seven cases, the detection of elevated BCR/ABL transcripts by quantitative PCR preceded signs of hematologic or cytogenetic disease progression by up to 8 months (median 6 months). Our data show that quantitative PCR analysis facilitates the monitoring of the response to IFN-alpha therapy and provides an effective diagnostic tool for the timely detection of recurrent disease. The employment of this technique greatly enhances the diagnostic possibilities in the management of chronic myelogenous leukemia.

Adult↗

PubMed1994

Absence of N-ras mutations in myeloid and lymphoid blast crisis of chronic myeloid leukemia.

Mutations within N-ras oncogene codons 12, 13, and 61 occur in approximately 25-30% of patients with acute nonlymphocytic leukemia and at a lower frequency (6-20%) in patients with acute lymphocytic leukemia. Moreover, N-ras mutations have been described in patients with chronic myeloid leukemia (CML) in blast crisis but have not been observed during the chronic phase of the disease. In view of the morphological and clinical similarities between acute leukemia and the blast crisis of CML, the question was raised whether the presence of N-ras mutations is associated with the phenotype of acute leukemia. We investigated leukemic cells from 100 patients with CML for the presence of N-ras mutations in the mutational hot spot codons. The cases analyzed included 87 diagnosed with different types of blast crisis and 13 cases in accelerated or chronic phase of the disease. Fragments from N-ras exons I and II containing the codons of interest were amplified by polymerase chain reaction and analyzed for the presence of point mutations by three different technical approaches, including specific oligonucleotide hybridization, direct sequencing, and single-strand conformation polymorphism analysis. N-ras mutations were not detected in any of the CML patients investigated. Only one patient, in whom the initial diagnosis of CML-blast crisis had been revised to chronic myelomonocytic leukemia, displayed an N-ras mutation within codon 13. Our data strongly suggest that N-ras mutations do not play a role in myeloid or lymphoid blast crisis of CML.

Base Sequence↗

PubMed1994

HLA class-I and -II antigens in chronic idiopathic autoimmune thrombocytopenia.

We studied MHC class-I and -II phenotypes in adult Caucasian patients with chronic idiopathic autoimmune thrombocytopenia (cAITP). Forty-five patients (median age 51 years, range 21-78 years) with a median disease duration of 7 years (range 2-26 years) were phenotyped for HLA-A, -B, -C by the standard lymphocytotoxicity test, HLA-DR and -DQ by restriction fragment-length polymorphism (RFLP), and -DP by oligonucleotide typing. Antiplatelet antibodies directed against glycoproteins Ib/IX and IIb/IIIa were determined by monoclonal antibody-specific immobilization of platelet antigens (MAIPA). The comparison of antigen frequencies of the whole group of patients with healthy controls revealed no significant difference for any of the MHC class-I or class-II specificities (p > 0.05). Patients were then divided into groups based on (a) their response to therapy, and (b) on whether they did or did not have detectable anti-platelet antibodies (n = 16 versus n = 29). All patients with a poor response to splenectomy carried the HLA-DPB1*0402 phenotype. The HLA-DPB1*1501 allele was found only among patients with detectable antiplatelet antibodies. These differences were not significant after correction for the number of tested antigens, however. Our data suggest that there is no association between MHC class-I/II alleles and adult cAITP or subgroups thereof.

Adult↗

PubMed1993

Early detection of relapse after bone marrow transplantation in patients with chronic myelogenous leukaemia.

In patients with chronic myelogenous leukaemia (CML) treated by allogeneic bone marrow transplantation (BMT), detection of residual leukaemic cells carrying the characteristic bcr/abl rearrangement by highly sensitive techniques, such as qualitative polymerase chain reaction (PCR), is of limited value in predicting disease progression. We have therefore adapted the PCR for quantitative assessment of bcr/abl rearranged cells and applied this technique to the monitoring of residual disease in 28 CML patients during up to 106 months of follow-up after BMT. In 5 patients, quantitative PCR revealed increasing amounts of the pathological bcr/abl message, indicating the presence of a proliferating neoplastic clone, and all 5 had a subsequent relapse of disease. By contrast, the remaining 23 patients have been in maintenance-free complete remission for up to 106 months post-BMT. The monitoring by quantitative PCR of residual leukaemic cells during the post-transplant course of CML patients may allow early detection of relapse and provide a rationale for the timely initiation of treatment.

Bone Marrow Transplantation↗

PubMed1993

Studies on oral contraceptive-induced changes in blood coagulation and fibrinolysis and the estrogen effect on endothelial cells.

Blood coagulation (fibrinogen, thrombin-antithrombin III complexes, TAT, and prothrombin fragment F1 + 2) and fibrinolytic parameters [fibrin split-product D-dimer, tissue plasminogen activator (t-PA) activity, plasminogen activator inhibitor-1 activity (PAI-1), and plasmin-antiplasmin-complexes (PAP)] were evaluated in 16 women on low estrogen (EE) oral contraceptive (OC) therapy. Blood samples were taken before and between days 18 and 22 of the first, third, and sixth treatment cycle. Fibrinogen levels were found significantly elevated during OC treatment compared with pretreatment values, while TAT and also F1 + 2 levels remained unchanged. Treatment-induced activation of fibrinolysis was documented by elevated D-dimer [pretreatment (pt): 172 ng/ml (range: 65-640 ng/ml), cycle 6 (c.6): 351 ng/ml (range: 93-960 ng/ml), p < 0.05)] and PAP [(pt: 46.6 ng/ml (13-220 ng/ml), c.6: 66.4 ng/ml (21-200 ng/ml), p < 0.05] plasma levels. Among the fibrinolytic components a decrease in PAI-1 [pt: 10.8 ng/ml (2-56 ng/ml), c.6: 5.3 ng/ml (2.2-14.4 ng/ml), p < 0.05] and an increase in t-PA activity [pt: 0.23 U/ml (0.17-0.45 U/ml), c.6: 0.33 U/ml (0.2-0.9 U/ml), p < 0.05] were detected. Experiments with cultured human endothelial cells (EC) showed that EE influenced neither EC hemostatic regulatory activities (tissue factor, thrombomodulin) nor the secretion of the fibrinolytic components t-PA and PAI-1.

Adult↗

PubMed1993

Frequent detection of BCR-ABL specific mRNA in patients with chronic myeloid leukemia (CML) following allogeneic and syngeneic bone marrow transplantation (BMT).

We performed a two-step polymerase chain reaction (PCR) to detect bcr-abl-specific mRNA in 440 peripheral blood and/or bone marrow samples of 30 chronic myeloid leukemia (CML) patients (mean 15, range 2-50 samples) following non T-cell-depleted allogeneic (n = 28) or syngeneic (n = 2) bone marrow transplantation (BMT). Median follow-up after BMT is 40 months (range 2-116 months), the median observation time 29 months (range 2-40 months). In 15 patients (50%), bcr-abl-specific mRNA could be detected following BMT. Bcr-abl positivity was rare in patients who were in hematological remission for at least 40 months (2/11). In five patients, PCR positivity was observed only once; all five patients are in complete hematological remission. Ten patients showed bcr-abl specific mRNA in two or more consecutive samples. Hematological relapse occurred in five of the latter patients. Bcr-abl positivity preceded hematological relapse in all cases. Bcr-abl positivity was detected more frequently in patients without graft-versus-host disease (GVHD) (11/15), than in patients with GVHD (4/15) (p < 0.02). Our data indicate that transient bcr-abl positivity is not usually followed by hematological relapse, while patients, who are positive in serial samples have a high risk of relapse.

Adult↗

PubMed1992

[Problems of long-term therapy with anticoagulants].

Oral anticoagulants are highly effective for the prevention of recurrence of venous thromboembolism and of thromboembolic complications in rheumatic and non-rheumatic atrial fibrillation, dilated cardiomyopathy and in patients with prosthetic heart valves, but less effective for prevention of arterial thrombosis. Bleeding is the main side effect, the risk of fatal bleeding is 0.2 to 0.4% per year, depending on the intensity of treatment. The problem of the standardization of the prothrombin time determination has been solved by the introduction of the international normalized ratio. Recent studies have shown that a lesser degree of anticoagulation (INR 2.0 to 3.0) is sufficient to prevent venous thromboembolism and cardiac emboli. The measurement of activation markers of coagulation will probably allow a more rational monitoring in the near future.

Administration, Oral↗

PubMed1992

Monitoring of residual disease in chronic myelogenous leukemia by quantitative polymerase chain reaction.

The polymerase chain reaction (PCR) has become a standard method for highly sensitive detection of the bcr/abl rearrangement in patients with chronic myelogenous leukemia (CML) or acute lymphoblastic leukemia (ALL). The exquisite sensitivity of the PCR facilitates the detection of residual leukemic cells after chemotherapy or after bone marrow transplantation. However, the detection of minimal residual disease does not yield any information on the malignant potential of the bcr/abl-rearranged cells. Qualitative PCR is therefore of limited prognostic value in the monitoring of residual leukemia. We have adapted the PCR for quantitative evaluation of cells carrying the bcr/abl rearrangement and by means of two exemplary cases of CML patients after bone marrow transplantation and under treatment with alpha-interferon, respectively, we show that this new technique is suitable for the long term follow-up of the activity of the residual bcr/abl rearranged clone. Longitudinal monitoring of residual disease by the technique presented provides a novel tool for detection of incipient relapse at a very early stage.

Adolescent↗

PubMed1991

Pure red cell aplasia in a case of Ph negative BCR/ABL rearranged CML with t(12;14)(q23;p11).

A patient with chronic myelogenous leukemia (CML) associated with pure red cell aplasia (PRCA) is reported. The occurrence of PRCA has been described previously in sporadic cases of Philadelphia chromosome (Ph) positive CML. In this patient, however, the Ph-chromosome was not detected; cytogenetic analysis revealed a t(12;14)(q23;p11) as the sole abnormality. Molecular studies by Southern and PCR analyses showed the rearrangement of the BCR and ABL sequences and expression of the chimeric bcr/abl mRNA, thus confirming the diagnosis of CML. To our knowledge, this is the first report on a case of PRCA associated with Ph negative CML at diagnosis. The possible connection between CML and PRCA is discussed.

Aged↗

PubMed1991

Detection of engraftment and mixed chimerism following bone marrow transplantation using PCR amplification of a highly variable region-variable number of tandem repeats (VNTR) in the von Willebrand factor gene.

Detection of host cells in peripheral blood and/or bone marrow (mixed chimerism) of patients who have undergone bone marrow transplantation (BMT) is possible using either immunological methods or cytogenetic or molecular genetic analysis. We shall report a new method for the detection of mixed chimerism, which makes use of the fact, that the von Willebrand factor (vWF) gene has a highly variable region-variable number of tandem repeats (VNTR)--within intron 40. vWF-VNTR amplification by the polymerase chain reaction (PCR) was performed as described by Peake et al. We have studied 185 peripheral blood and/or bone marrow samples of 26 patients. Median time after BMT was 14 months (range 1-83 months). Of the 11 patients who were studied sequentially during the first 100 days following BMT, mixed chimerism was detected in four, but only transiently. None of these patients has relapsed so far. Of 18 patients who were studied more than 100 days after BMT mixed chimerism was found in three; two of these patients have subsequently relapsed. The advantages of this new method are: (a) it is informative in a high percentage of patients; (b) it requires only small amounts (200 microliters) of peripheral blood; (c) reliable results can be obtained at leukocyte counts of even less than 50 per microliters. The clinical relevance and sensitivity of the method compared with established methods for detection of mixed chimerism remain to be determined.

Bone Marrow↗

PubMed1991

[Chronic myeloid leukemia].

Chronic myelocytic leukemia is a malignant clonal disorder which, after a chronic phase of about 3 to 4 years, progresses to blastic transformation. The disease is incurable by conventional cytostatic treatment. Once blastic transformation has ensued, survival is limited to weeks or months. Interferon may prolong the chronic phase, but data are controversial. Allogeneic bone marrow transplantation may cure 40 to 70% of patients treated while in chronic phase. Survival is about 20% in advanced disease, depending mainly on age, sex of donor and clinical condition. Allogenic bone marrow transplantation was hitherto restricted to patients having an HLA-identical bone marrow donor. Volunteer bone marrow donor registries now contain about 400,000 registered unrelated healthy donors: The chance of finding an unrelated bone marrow donor is now between 10 and 60%, and the chance will increase when donor registries expand.

Antineoplastic Agents↗