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Biomedical subjects

O A Haas

Publications and source records attributed to O A Haas.

At least 19 recordsLinked to original sources
PubMed2007

Distinct fluctuations of ammonia levels during asparaginase therapy for childhood acute leukemia.

BACKGROUND: The enzyme asparaginase (L-Asp) catalyses the hydrolysis of the non-essential amino acids asparagine and glutamine to aspartic and glutamic acid and ammonia. Ammonia therefore represents a direct metabolite of the biochemical reaction induced by this enzyme. However, data regarding the dynamics and clinical relevance of ammonia levels during L-Asp therapy are lacking. PROCEDURE: We prospectively followed the dynamics of ammonia levels during L-Asp containing induction therapy according to the ALL-BFM 2000 protocol in 10 pediatric patients with acute lymphoblastic leukemia (ALL), in order to assess the possible relevance of ammonia levels for clinical practice and its use as a possible surrogate parameter of L-Asp enzyme activity. RESULTS: We observed a significant elevation of ammonia levels 1 day after intravenous L-Asp administration with ammonia levels reaching up to the seventh fold of normal values, followed by a steep decline to basal values within another 2 days, resulting in an undulating course of ammonia concentrations during L-Asp containing induction treatment. CONCLUSIONS: Although there are potential neurotoxic properties of ammonia, central nervous system (CNS) toxicity has not been observed in our study and is generally not seen as a common side effect of L-Asp therapy. Furthermore, due to the characteristic fluctuation profile, ammonia levels may represent a suitable surrogate parameter of L-Asp enzyme activity and may enable the monitoring of silent inactivation of L-Asp.

Adolescent↗
PubMed2006

Characterisation of the GRAF gene promoter and its methylation in patients with acute myeloid leukaemia and myelodysplastic syndrome.

We report the isolation of the 5' flanking region of GRAF (GTPase regulator associated with the focal adhesion kinase), previously described as a putative tumour suppressor gene of acute myelogenous leukaemia and myelodysplastic syndrome, and demonstrate its promoter activity in reporter gene assays. Two putative protein-binding sites are identified of which one was sensitive to CpG methylation. The suppressed GRAF expression could be restored in leukaemia cell lines by treatment with a demethylating agent and an inhibitor of histone deacetylases. In contrast to normal tissues, which tested negative for GRAF promoter methylation, 11 of 29 (38%) bone marrow samples from patients with acute myeloid leukaemia or myelodysplastic syndrome were positive.

Acute Disease↗
PubMed2006

The MLL recombinome of acute leukemias.

Chromosomal rearrangements of the human MLL gene are a hallmark for aggressive (high-risk) pediatric, adult and therapy-associated acute leukemias. These patients need to be identified in order to subject these patients to appropriate therapy regimen. A recently developed long-distance inverse PCR method was applied to genomic DNA isolated from individual acute leukemia patients in order to identify chromosomal rearrangements of the human MLL gene. We present data of the molecular characterization of 414 samples obtained from 272 pediatric and 142 adult leukemia patients. The precise localization of genomic breakpoints within the MLL gene and the involved translocation partner genes (TPGs) was determined and several new TPGs were identified. The combined data of our study and published data revealed a total of 87 different MLL rearrangements of which 51 TPGs are now characterized at the molecular level. Interestingly, the four most frequently found TPGs (AF4, AF9, ENL and AF10) encode nuclear proteins that are part of a protein network involved in histone H3K79 methylation. Thus, translocations of the MLL gene, by itself coding for a histone H3K4 methyltransferase, are presumably not randomly chosen, rather functionally selected.

Acute Disease↗
PubMed2006

Small supernumerary marker chromosomes--progress towards a genotype-phenotype correlation.

Small supernumerary marker chromosomes (sSMC) are still a major problem in clinical cytogenetics as they are too small to be characterized for their chromosomal origin by traditional banding techniques, but require molecular cytogenetic techniques for their identification. Apart from the correlation of about one third of the sSMC cases with a specific clinical picture, i.e. the i(18p), der(22), i(12p) (Pallister Killian syndrome) and inv dup(22) (cat-eye) syndromes, most of the remaining sSMC have not yet been correlated with clinical syndromes. Recently, we reviewed the available >1600 sSMC cases (Liehr T, sSMC homepage: http://mti-n.mti.uni-jena.de/~huwww/MOL_ZYTO/sSMC.htm). A total of 387 cases (including the 45 new cases reported here) have been molecularly cytogenetically characterized with regard to their chromosomal origin, the presence of euchromatin, heterochromatin and satellite material. Based on analysis of these cases we present the first draft of a basic genotype-phenotype correlation for sSMC for all human chromosomes apart from the chromosomes Y, 10, 11 and 13.

Adolescent↗
PubMed2004

High expression of the sister-chromatid separation regulator and proto-oncogene hSecurin occurs in a subset of myeloid leukaemias but is not implicated in the pathogenesis of aneuploidy.

Aneuploidy is considered to play an important role in the pathogenesis of malignancies. We were interested whether abnormalities of the sister-chromatid separation regulator and proto-oncogene hSecurin occurred in myeloid leukaemias, and whether such abnormalities correlated with aneuploidy. The expression of hSecurin was assessed by real-time quantitative PCR in samples from patients with acute myeloid leukaemia (AML, n=70), chronic myeloid leukaemia (CML) in chronic phase (CP, n=20) or blast phase (BP, n=12), and granulocytes as well as mononuclear cells (MNCs) from healthy donors (n=21). Median hSecurin expression in AML with normal karyotypes was not significantly different from AML showing aneuploidy, CML BP or cells from healthy donors. However, hSecurin expression in CML CP was significantly increased compared to AML with normal karyotypes (1.82-fold; P<0.001), CML BP (3.18-fold; P<0.001), MNCs (3.17-fold; P<0.001) and granulocytes (2.69 fold; P<0.001) from healthy donors. Mutations in the coding region of hSecurin were not detected. These results do not support a major role of hSecurin in the development of aneuploidy in myeloid leukaemias. However, high expression of hSecurin may be of pathogenetic relevance in a subset of patients with regard to its potential to stimulate angiogenesis and to interact with the DNA-damage response pathway.

Acute Disease↗
PubMed2004

Impact of cytogenetics on the prognosis of adults with de novo AML in first relapse.

Karyotype is an important prognostic factor in patients with newly diagnosed acute myeloblastic leukaemia (AML). The prognostic value of cytogenetics on the outcome of patients with AML in relapse has not yet been well defined. We analysed the clinical outcome of 152 patients with de novo, chemotherapy-treated AML in first relapse according to the cytogenetic classification of the United Kingdom Medical Research Council. The rate of second complete remission (CR) (88, 64 and 36%) and the probability of survival at 3 years (43, 18 and 0%) were significantly different between the favourable, intermediate and adverse cytogenetic risk groups, respectively. Compared to the favourable group, the relative risk (RR) of death (multivariate analyses) was 2.6 (confidence interval (CI): 1.5-4.4, P<0.001) for the intermediate and 3.7 (CI: 1.7-7.9, P=0.001) for the adverse group. The prognostic value of the duration of first CR was confirmed (RR of death: 2.0 (CI: 1.0-4.0) for each additional year in first CR), whereas the FLT3 mutation obtained at diagnosis did not markedly influence the outcome of patients with AML in relapse. In conclusion, our results indicate that both karyotype and the duration of first CR are independent prognostic factors for patients with de novo AML in first relapse.

Acute Disease↗
PubMed2004

In vitro drug-resistance profile in infant acute lymphoblastic leukemia in relation to age, MLL rearrangements and immunophenotype.

Acute lymphoblastic leukemia (ALL) in infants under 1 year is strongly associated with translocations involving 11q23 (MLL gene), CD10-negative B-lineage (proB) immunophenotype, and poor outcome. The present study analyses the relationship between age, MLL rearrangements, proB-lineage, and in vitro drug resistance determined using the MTT assay. Compared to 425 children aged over 1 year with common/preB (c/preB) ALL, the 44 infants were highly resistant to steroids (for prednisolone (PRED) more than 580-fold, P=0.001) and L-asparaginase (L-ASP) (12-fold, P=0.001), but more sensitive to cytarabine (AraC) (1.9-fold, P=0.001) and 2-chlorodeoxyadenosine (2-CdA) (1.7-fold, P<0.001). No differences were found for vincristine, anthracyclines, thiopurines, epipodophyllotoxines, or 4-hydroperoxy (HOO)-ifosfamide. ProB ALL of all ages had a profile similar to infant ALL when compared with the group of c/preB ALL: relatively more resistant to L-ASP and PRED (and in addition thiopurines), and more sensitive to AraC and 2-CdA. Age was not related to cellular drug resistance within the proB ALL group (<1 year, n=32, vs >/=1 year, n=19), nor within the MLL-rearranged ALL (<1 year, n=34, vs >/=1 year, n=8). The translocation t(4;11)(q21;q23)-positive ALL cases were more resistant to PRED (>7.4-fold, P=0.033) and 4-HOO-ifosfamide (4.4-fold, P=0.006) than those with other 11q23 abnormalities. The expression of P-glycoprotein, multidrug-resistance protein, and lung-resistance protein (LRP) was not higher in infants compared to older c/preB ALL patients, but LRP was higher in proB ALL and MLL-rearranged ALL of all ages. In conclusion, infants with ALL appear to have a distinct in vitro resistance profile with the proB immunophenotype being of importance. The role of MLL cannot be excluded, with the t(4;11) being of special significance, while age appears to play a smaller role.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2004

RT-PCR and FISH analysis of acute myeloid leukemia with t(8;16)(p11;p13) and chimeric MOZ and CBP transcripts: breakpoint cluster region and clinical implications.

The translocation t(8;16)(p11;p13) is associated with acute myeloid leukemia displaying monocytic differentiation (AML FAB M4/5) and fuses the MOZ (also named MYST3) gene (8p11) with the CBP (also named CREBBP) gene (16p13). Detection of the chimeric RNA fusions has proven difficult; only three studies have described successful amplification of the chimeric MOZ-CBP and CBP-MOZ fusions by reverse transcriptase-polymerase chain reaction (RT-PCR). We analyzed four cases of AML M4/5 with t(8;16)(p11;p13) by RT-PCR and fluorescence in situ hybridization (FISH) and characterized the reciprocal RNA fusions from three cases. We cloned both genomic translocation breakpoints from one case by long-range PCR and successfully applied RT-PCR to monitor minimal residual disease (MRD) between clinical complete remission and relapse. In three cases, the genomic breakpoints occurred in MOZ intron 16 and CBP intron 2. In one case, no fusion transcript was detected. The available data suggest clustering of t(8;16)(p11;p13) breakpoints in these introns leading to reciprocal in-frame MOZ exon 16/CBP exon 3 and in-frame CBP exon 2/MOZ exon 17 chimeric transcripts in the majority of cases. The described RT-PCR strategy may be valuable both for the routine detection of the t(8;16)(p11;p13) as well as for monitoring of MRD in this prognostically unfavorable patient group.

Acetyltransferases↗
PubMed2004

Incidence and relevance of secondary chromosome abnormalities in childhood TEL/AML1+ acute lymphoblastic leukemia: an interphase FISH analysis.

The aim of the present study was to determine the frequency and clinical relevance of the most common secondary karyotype abnormalities in TEL/AML1+ B-cell precursor acute lymphoblastic leukemia (ALL) as assessed with fluorescence in situ hybridization (FISH) analyses. Screening of 372 patients who were enrolled in two consecutive Austrian childhood ALL multicenter trials identified 94 (25%) TEL/AML1+ cases. TEL deletions, trisomy 21 and an additional der(21)t(12;21) were detected in 52 (55%), 13 (14%) and 14 (15%) TEL/AML1+ patients, respectively. The 12p aberrations (P=0.001) and near tetraploidy (P=0.045) were more common in TEL/AML1+ patients, whereas the incidence of diploidy, pseudodiploidy, hypodiploidy, low hyperdiploidy, near triploidy, del(6q), chromosome 9 and 11q23 abnormalities was similar among TEL/AML1+ and TEL/AML1- patients. None of the TEL/AML1+ patients had a high hyperdiploid karyotype. Univariate analysis indicated that among TEL/AML1+ patients those with a deletion of the nontranslocated TEL allele had a worse prognosis than those without this abnormality (P=0.034). We concluded that the type and incidence of the most common secondary aberrations in TEL/AML1+ ALL can be conveniently identified with little additional effort during interphase screening with appropriate TEL and AML1 FISH probes. We also provided preliminary evidence that the deletion of the nontranslocated TEL allele may adversely influence the clinical course of TEL/AML1+ ALL.

Child↗
PubMed2003

Circulating myeloid colony-forming cells predict survival in myelodysplastic syndromes.

The growth characteristics and the prognostic value of cytokine-stimulated myeloid colony formation from peripheral blood mononuclear cells (PBMC) of patients with myelodysplastic syndromes (MDS) are largely unknown. In this study we have determined the number of myeloid colony-forming units (mCFUs) in semisolid medium from 112 MDS patients and correlated them with French-American-British (FAB) type, the international prognostic scoring system (IPSS), karyotype, peripheral blood (PB) and bone marrow (BM) blast cells, cytopenias, lactate dehydrogenase (LDH), and survival data. Concerning the FAB classification, lower median mCFUs were found in patients with refractory anemia (RA) and refractory anemia with ringed sideroblasts (RARS) compared to refractory anemia with excess of blast cells (RAEB) and refractory anemia with excess of blasts cells in transformation (RAEB-T). In vitro growth in MDS clearly correlated with the cytogenetic risk groups defined by the IPSS (30.5/10(5) PBMCs with favorable karyotypes, 191 in the intermediate prognostic group, 677 with unfavorable cytogenetics, p=0.015 favorable vs unfavorable). BM blast cells >5% (60.5 vs 255 colonies, p=0.032) as well as LDH levels above the normal limit (64.5 vs 425 colonies, p=0.045) were also associated with higher colony formation. Patients were stratified according to the number of circulating mCFUs into a low growth, intermediate growth and high growth group. Median survival was 343 days in the high growth, 1119 days in the low growth, and 2341 days in the intermediate growth group ( p=0.0002). Multivariate analyses revealed colony growth ( p=0.0056), PB blast cells ( p=0.0069), cytogenetic risk group ( p=0.024), and platelet count ( p=0.018) to predict survival in our patients. After inclusion of the IPSS risk categories, mCFU levels remained a highly predictive parameter for survival ( p=0.0056) and acute myeloblastic leukemia (AML) transformation ( p=0.0003).

Blood Cells↗
PubMed2003

PAX5/ETV6 fusion defines cytogenetic entity dic(9;12)(p13;p13).

Recurrent chromosomal abnormalities present in malignant cells often define subentities with unique biological and clinical features. The molecular identification of genes involved in genetic alterations has led to the characterization of fusion genes with neoplastic properties. However, for many nonrandom translocations including the dic(9;12)(p11-13;p11-12), the molecular equivalent has not as yet been identified. The dicentric translocation dic(9;12) is a recurrent chromosome abnormality that accounts for close to 1% of childhood acute lymphoblastic leukemia (ALL). This specific alteration occurs almost exclusively in B-progenitor ALL, and unlike many other nonrandom translocations, is associated with an excellent prognosis. In this work, we provide strong evidence that the PAX5/ETV6 fusion transcript defines the clinical and biological entity that is associated with the presence of a dic(9;12) chromosome. As the PAX5 and ETV6 genes are localized at 9p13 and 12p13, respectively, the cytogenetic description of the dic(9;12)-PAX5/ETV6 rearrangement should be refined to dic(9;12)(p13;p13).

Adolescent↗
PubMed2003

Lineage-specific chimaerism after stem cell transplantation in children following reduced intensity conditioning: potential predictive value of NK cell chimaerism for late graft rejection.

Chimaerism of FACS-sorted leucocyte subsets (CD14+, CD15+, CD3-/56+, CD3+/4+, CD3+/8+, CD19+) was monitored prospectively between days +14 and +100 in 39 children undergoing allogeneic stem cell transplantation with reduced intensity-conditioning regimens. Cell subsets exceeding 1% of nucleated cells were subject to cell sorting. Chimaerism was analysed by dual-colour FISH and/or by short tandem repeat-polymerase chain reaction. The chimaerism pattern on day +28 was evaluated with regard to its correlation with graft rejection. Of 39 patients, nine patients had donor chimaerism (DC) in all subsets. Mixed/recipient chimaerism (MC/RC) was detectable within T cells in 62%, within NK cells in 39% and within monocytes and granulocytes in 38% of the patients. The correlation of secondary graft rejection with the chimaerism pattern on day +28 revealed the strongest association between RC in NK-cells (P<0.0001), followed by T cells (P=0.001), and granulocytes and monocytes (P=0.034). Notably, patients with RC in T cells rejected their graft only if MC or RC was also present in the NK-cell subset. By contrast, none of the children with DC in NK cells experienced a graft rejection. These observations suggest that, in the presence of recipient T-cell chimaerism, the chimaerism status in NK-cells on day +28 might be able to identify patients at high risk for late graft rejection.

Adolescent↗
PubMed2002

Analysis of SH2D1A mutations in patients with severe Epstein-Barr virus infections, Burkitt's lymphoma, and Hodgkin's lymphoma.

Mutations or deletions in the SH2D1A (src homology 2 domain protein 1A) gene result in a severe immunodeficiency called X-linked lymphoproliferative (XLP) disease. XLP is primarily characterized by a defective immune response against the Epstein-Barr virus (EBV), resulting in an unusually severe and often fatal clinical course following EBV infection. The second major cause of death is the development of B cell lymphomas, both in EBV-infected and EBV-negative patients. To study whether the clinical manifestation of XLP gene defects and/or polymorphisms extends beyond the classically recognized phenotype, we analyzed patients for the presence of SH2D1A gene alterations who presented with fatal or nonfatal, yet unusually severe or chronic EBV infections, and other possibly EBV-associated diseases, such as Hodgkin's lymphomas or nonendemic Burkitt's lymphomas and Burkitt-type leukemias. We identified mutations of the SH2D1A gene only in the majority of patients presenting with fatal mononucleosis or an XLP family history, but not in any of the other patients studied. The only alteration determined was a polymorphism in the 5' region of the SH2D1A gene both in patient groups as well as in controls.

Burkitt Lymphoma↗
PubMed2001

Presence of N regions in the clonotypic DJ rearrangements of the immunoglobulin heavy-chain genes indicates an exquisitely short latency in t(4;11)-positive infant acute lymphoblastic leukemia.

Childhood acute lymphoblastic leukemia (ALL) is frequently initiated in utero at a time of developmentally regulated insertion of N regions into the DJ(H) rearrangements of immunoglobulin heavy-chain (Ig(H)) genes. Here it is shown that N regions are present in the clonotypic DJ(H) rearrangements in 11 of 12 infant ALLs with t(4;11). These data are compared with the 122 previously published DJ(H) sequences and were found to have a pattern similar to that of ALL in children older than 3 years at diagnosis but were unlike that in children younger than 3 years who predominantly lack N regions. These findings, therefore, indicate that t(4;11)-positive infant ALL is initiated later in fetal development than most B-cell precursor ALL from children younger than 3 years and that they have a shorter latency period already in utero.

Base Sequence↗
PubMed2001

A novel gene, NSD1, is fused to NUP98 in the t(5;11)(q35;p15.5) in de novo childhood acute myeloid leukemia.

The recurrent translocation t(5;11)(q35;p15.5) associated with a 5q deletion, del(5q), has been reported in childhood acute myeloid leukemia (AML). We report the cloning of the translocation breakpoints in de novo childhood AML harboring a cryptic t(5;11)(q35;p15.5). Fluorescence in situ hybridization (FISH) analysis demonstrated that the nucleoporin gene (NUP98) at 11p15.5 was disrupted by this translocation. By using 3'--rapid amplification of complementary DNA ends (3'-RACE) polymerase chain reaction, we identified a chimeric messenger RNA that results in the in-frame fusion of NUP98 to a novel gene, NSD1. The NSD1 gene has 2596 amino acid residues and a 85% homology to the murine Nsd1 with the domain structure being conserved. The NSD1 gene was localized to 5q35 by FISH and is widely expressed. The reciprocal transcript, NSD1-NUP98, was also detected by reverse transcriptase--polymerase chain reaction. This is the first report in which the novel gene NSD1 has been implicated in human malignancy. (Blood. 2001;98:1264-1267)

Acute Disease↗