Biomedical subjects

C R Bartram

Publications and source records attributed to C R Bartram.

At least 55 records · Page 3Linked to original sources

PubMed1998

Mutations in the gene for the common gamma chain (gammac) in X-linked severe combined immunodeficiency.

X-linked severe combined immunodeficiency (XSCID) constitutes a disorder of the immune system caused by mutations in the gene encoding the common gamma chain (gammac), a subunit of the IL-2, IL-4, IL-7, IL-9 and IL-15 receptors, which are necessary for lymphocyte development and function. In this study the IL2RG gene of 31 patients with severe combined immunodeficiency (SCID) was examined by nonradioactive single-strand conformation polymorphism and sequence analysis. Among the 11 patients with XSCID, ten different mutations were identified in the IL2RG gene, including eight novel mutations. Ninety percent of the mothers of the XSCID patients are carriers of the mutated allele. One patient showed low numbers of B-cells, a striking deviation from the classical B-cell-positive and T-cell-negative phenotype.

B-Lymphocytes↗

PubMed1998

High rate of chromosome abnormalities detected by fluorescence in situ hybridization using BCR and ABL probes in adult acute lymphoblastic leukemia.

The value of dual-color fluorescence in situ hybridization (FISH) with BCR and ABL probes for the detection of the Philadelphia (Ph) translocation and of other alterations involving ABL and/or BCR was evaluated in adult acute lymphoblastic leukemia (ALL). One hundred and four patients were studied prospectively using interphase nuclei FISH, chromosome analysis (CA), and PCR assays for the chimeric BRC/ABL transcript. FISH detected a Ph translocation in 24 cases (23.1%), as was confirmed by CA and/or PCR. FISH revealed a false positive diagnosis of a Ph translocation in four cases (5% false positive rate). Among 54 cases with combined FISH, CA and PCR assays, FISH failed to establish a correct diagnosis in 3.7%, PCR in 5.6%, and CA in 7.4%. The combination of two screening methods led to discrepant results in 9.3% (FISH + PCR), 11.1% (FISH + CA), or 13% (CA + PCR) of the cases. In seven of 80 (8.8%) Ph-negative patients, gain of BCR and/or ABL was identified. Overall, FISH detected alterations of the BCR and/or ABL genes with an incidence of 29.8% of the current study. Due to the possibility of false positive diagnosis of a Ph translocation using dual-color FISH the combination with chromosome and/or RT-PCR analyses is recommended in adult ALL patients.

Adolescent↗

PubMed1998

The ATM gene and susceptibility to childhood T-cell acute lymphoblastic leukaemia.

Ataxia-telangiectasia (A-T) is a multisystem recessive disease characterized by cerebellar ataxia, oculocutaneous telangiectasias, immunodeficiency and increased risk of cancer. The ATM gene, responsible for A-T, was recently cloned at human chromosome band 11q22-23, a region of frequent alterations in childhood acute lymphoblastic leukaemia (ALL). Children with A-T frequently develop T-ALL. We investigated 18 T-ALL samples for ATM mutations and loss of heterozygosity (LOH) at the ATM locus. No mutations of ATM were found within the coding region in the 18 T-ALL samples, and LOH at the ATM locus was detected in three. The ATM gene appears to be an infrequently altered tumour suppressor gene in childhood T-ALL.

Ataxia Telangiectasia Mutated Proteins↗

PubMed1997

Intracellular signaling of the Ufo/Axl receptor tyrosine kinase is mediated mainly by a multi-substrate docking-site.

Ufo/Axl belongs to a new family of receptor tyrosine kinases with an extracellular structure similar to that of neural cell adhesion molecules. In order to elucidate intracellular signaling, the cytoplasmic moiety of Ufo/Axl was used to screen an expression library according to the CORT (cloning of receptor targets) method. Three putative Ufo substrates were identified: phospholipase Cgamma1 (PLCgamma), as well as p85alpha and p85beta subunits of phosphatidylinositol 3'-kinase (PI3-kinase). Subsequently, chimeric EGFR/Ufo receptors consisting of the extracellular domains of the epidermal growth factor receptor (EGFR) and the transmembrane and intracellular moiety of Ufo were engineered. Using different far-Western blot analyses and coimmunoprecipitation assays, receptor binding of PLCgamma and p85 proteins as well as GRB2, c-src and lck was examined in vitro and in vivo. Competitive inhibition of substrate binding and mutagenesis experiments with EGFR/Ufo constructs revealed C-terminal tyrosine 821 (EILpYVNMDEG) as a docking site for multiple effectors, namely PLCgamma, p85 proteins, GRB2, c-src and lck. Tyrosine 779 (DGLpYALMSRC) demonstrated an additional, but lower binding affinity for the p85 proteins in vitro. In addition, binding of PLCgamma occurred through tyrosine 866 (AGRpYVLCPST). Moreover, our in vivo data indicate that further direct or indirect binding sites for PLCgamma, GRB2, c-src and lck on the human Ufo receptor may exist.

Blotting, Western↗

PubMed1997

Molecular analysis of the secretory phospholipase A2 gene, a candidate of Mom1 gene, in neuroblastomas.

Mice with hereditary intestinal polyposis have mutations of the APC gene which causes formation of multiple polyps. At least one other gene influences the susceptibility for development of polyps in mice, and the locus was named Mom1. The causative gene for the Mom1 locus has recently been cloned and was found to be identical to the secretory type II phospholipase A2 (PLA2S-II) gene. Although the mechanism of contribution of PLA2S-II to formation of polyps is unclear, abnormalities of the PLA2S-II gene contribute to cellular transformation in mice. We speculated that this gene could contribute to tumorigenesis in human neoplasms. The human homologue of this gene maps to 1p35-36.1. Chromosomal deletions involving this region are frequently observed in neuroblastomas. We analyzed 19 neuroblastomas to detect point mutations of the PLA2S-II gene by PCR-single strand conformational polymorphism (SSCP). A polymorphism was detected at codon 32; no point mutations were found in the coding region of the gene. Moreover, in cases that were heterozygous at codon 32, three samples had hemizygous deletion of the gene. Taken together, PLA2S-II is frequently hemizygously deleted, but no point mutations are observed in neuroblastomas.

Abdominal Neoplasms↗

PubMed1997

T cell receptor Ddelta2Ddelta3 rearrangement: a suitable allele-specific marker for the detection of minimal residual disease in childhood acute lymphoblastic leukemia.

The applicability of T cell receptor (TCR) Ddelta2Ddelta3 junctional regions for the detection of minimal residual disease (MRD) was examined in childhood acute lymphoblastic leukemia (ALL). Southern blot analysis showed a Ddelta2Ddelta3 rearrangement in 22 of 172 (13%) precursor-B ALL. No Ddelta2Ddelta3 rearrangement was identified in 29 T-ALL cases. Three patients exhibited Ddelta2Ddelta3 recombinations in both alleles. Sequence analysis of Ddelta2Ddelta3 junctions revealed extensive diversity due to the random insertion and deletion of nucleotides at the joining site. PCR analysis utilizing allele-specific probes or oligonucleotides generated on the basis of Ddelta2Ddelta3 junctional sequences reached a sufficient sensitivity of 10(-4) to 10(-5) in the majority of cases. In four of 25 (16%) rearranged alleles, however, the 5' heptamer-nonamer recombination signal sequence (RSS) of the Ddelta2 segment had recombined directly to the 3' heptamer-nonamer RSS of the Ddelta3 segment thus generating a so-called signal junction. Respective heptamer-heptamer junctions are not suited to design allele-specific oligonucleotides for the detection of MRD because of their limited diversity and hence specificity.

Alleles↗

PubMed1997

TEL is one of the targets for deletion on 12p in many cases of childhood B-lineage acute lymphoblastic leukemia.

Abnormalities of the short arm of chromosome 12 including loss of heterozygosity (LOH) and TEL/AML-1 fusion resulting from a t(12;21)(p13;q22) translocation are frequently observed in childhood acute lymphoblastic leukemia (ALL). We investigated 21 DNA samples of childhood ALL which had LOH at 12p13. Rearrangement of TEL was observed in eight cases and another case showed a homozygous deletion of TEL. Two informative samples with TEL rearrangement had a deletion localized to the 5' region of this gene. The deletion in these two cases includes the helix-loop-helix (HLH) domain. This is consistent with the hypothesis that the normal tel can heterodimerize with the TEL/AML-1 gene product and inhibit the transforming capacity of the chimeric protein. Presumably, loss of the HLH of the normal remaining TEL allele abrogates this tumor suppressor-like function. The case with homozygous deletion of TEL is also consistent with this gene having qualities of a tumor suppressor. One unusual case had T-ALL rather than B-lineage ALL and the leukemic cells had rearrangement of TEL, but they did not have an alteration of the remaining TEL allele suggesting that the etiology of this disease may be different. This analysis further emphasizes the importance of loss of the normal TEL allele in childhood precursor B-lineage ALL.

Blotting, Southern↗

PubMed1997

Germline configuration of nfkb2, c-rel and bcl3 in childhood acute lymphoblastic leukemia (ALL).

The well-known family of NF-kappaB/Rel transcription factors is a central regulator of growth, differentiation and apoptosis in hematopoietic cell lineages. There is increasing evidence for their role in malignant transformation, especially in lymphomas. To study the possible involvement of NF-kappaB/Rel genes in the development of pediatric acute lymphoblastic leukemia (ALL), DNA samples from 140 patients were examined by Southern blot analysis. All samples revealed germline configuration of nfkb2, c-rel, and bcl3, indicating that structural alterations of these members of the NF-kappaB/Rel family are extremely rare, if existing at all in childhood ALL.

Adolescent↗

PubMed1997

Homozygous deletions at 9p21 in childhood acute lymphoblastic leukemia detected by microsatellite analysis.

To gain a fuller understanding of the role of deletions of chromosome 9 in the development of childhood acute lymphoblastic leukemia (ALL), we performed detailed deletional mapping of chromosome 9 in 54 primary ALL samples with matched normal DNA using 22 highly polymorphic markers; and this information was combined with our previous data concerning the presence of deletions of CDKN2/INK4A/p16 and CDKN2B/INK4B/p15 in these samples. We have found a very high frequency of loss of heterozygosity (LOH) (31 of 54 cases (57%)) on chromosome arm 9p. As expected, the smallest region of LOH was between D9S1747 and D9S1748 at 9p21, including CDKN2/INK4A/p16, but excluding CDKN2B/INK4B/p15. Homozygous deletions at 9p21 occurred in 23 of 54 (43%) samples (seven of 11 (64%) T-ALL, 16 of 45 (36%) precursor-B ALL). We detected seven cases of homozygous deletions at 9p21 which had not been detected by Southern blot hybridization, showing the power of microsatellite analysis in detecting homozygous deletions. In most cases, homozygous deletions were limited to the region between D9S1747 and CDKN2B/INK4B/p15. We have attempted to determine the mechanism and timing of 9p deletions. Of the 23 samples with homozygous deletions at 9p21, 21 samples had surrounding large LOH. Of the 29 samples with LOH of 9p, homozygous deletion at 9p21 was identified in 22 cases. In addition, six patients have been studied at diagnosis and relapse, all six showed the same 9p21 structure at relapse (normal, three patients; hemizygous deletions, two patients; homozygous deletion, one patient) as their initial presentation. Finally, three patients (homozygous deletion, one patient; hemizygous deletion, two patients) had the IFN-alpha rather than CDKN2/INK4A/p16 deleted. In summary, these data further emphasize the importance of 9p21 loss in the development of childhood ALL.

Carrier Proteins↗

PubMed1997

Microsatellite instability and other molecular abnormalities in childhood acute lymphoblastic leukaemia.

Microsatellite instability (MSI) has been considered to represent the defect of DNA mismatch repair systems and has been implicated in the tumourigenesis of several human malignancies. To investigate the possible presence of microsatellite instability in childhood acute lymphoblastic leukaemia (ALL), we examined 48 primary ALL samples. Instability was determined at 85 different microsatellite loci localized to 12 different chromosome arms. Microsatellite instability was detected in five (10%) samples. Interestingly, the instability was found at chromosomal regions associated with frequent alterations. Two samples had instability at the microsatellite marker within the TEL gene on chromosome arm 12p. Two other samples had instability at a microsatellite marker close to CDKN2/p16 on 9p; one of these samples had a homozygous deletion at 9p21. The fifth sample had instability at the microsatellite marker on 6q, which we have found is a frequent region of loss of heterozygosity in childhood ALL. Taken together, instability was rare in childhood ALL, but was localized to the three most frequently deleted chromosome regions in childhood ALL, suggesting that localized microsatellite instability may identify a fragile chromosomal region which could result in alteration of surrounding target genes and lead to leukaemia.

Blotting, Southern↗

PubMed1997

Molecular response of CML patients treated with interferon-alpha monitored by quantitative Southern blot analysis. German chronic myeloid leukaemia (CML) Study Group.

We analysed 459 samples from 206 chronic myeloid leukaemia (CML) patients at diagnosis and during or after treatment with interferon-alpha (IFN-alpha) by quantitative Southern blot analysis for BCR rearrangement. In a minority (2%) of Ph-positive patients, no BCR rearrangement was detectable due to breakpoints outside the major breakpoint cluster region (M-bcr) or possibly due to M-bcr deletions. Results from 235 samples were compared with the proportion of Ph-positive metaphases found in contemporaneous bone marrow specimens analysed by conventional cytogenetics. The rank correlation between both methods was 0.82 (P < 0.001). The proportion of CML cells in samples determined by Southern blot analysis (BCR ratio) was significantly different between cytogenetically-defined minor, partial, and complete response groups (P < 0.001). Empirically-derived cut-off points in the BCR ratio were introduced in order to define molecular response groups for comparison to standard cytogenetic response groups: a BCR ratio of 0% was defined as complete molecular response and ratios of 1-24%, 25-50%, and > 50% were defined as partial, minor, and no molecular response, respectively. Using these cut-off points the concordance between both methods was 67% (P < 0.0001), a major cytogenetic response could be predicted or excluded in more than 90% of cases (P < 0.0001). Our findings demonstrated that quantitative Southern blot was as sensitive as cytogenetics and as peripheral blood samples are suitable for this technique it should be considered as the method of choice for routine monitoring IFN-alpha therapy in CML patients.

Adolescent↗

PubMed1997

[Predictive tumor diagnosis in hereditary tumor disposition?].

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Female↗

PubMed1996

TEL/AML-1 dimerizes and is associated with a favorable outcome in childhood acute lymphoblastic leukemia.

Polymerase chain reaction-based screening of childhood acute lymphoblastic leukemia (ALL) samples showed that a TEL/AML1 fusion transcript was detected in 27% of all cases, representing the most common known gene rearrangement in childhood cancer. The TEL/AML1 fusion results from a t(12;21)(p13;q22) chromosomal translocation, but was undetectable at the routine cytogenetic level. TEL/AML1-positive patients had exclusively B-lineage ALL, and most patients were between the ages of 2 and 9 years at diagnosis. Only 3/89 (3.4%) adult ALL patients were TEL/AML1-positive. Most importantly, TEL/AML1-positive children had a significantly lower rate of relapse compared with TEL/AML1-negative patients (0/22 v 16/54, P = .004). Co-immunoprecipitation experiments demonstrated that TEL/AML-1 formed homodimers in vitro, and heterodimerized with the normal TEL protein when the two proteins were expressed together. The elucidation of the precise mechanism of transformation by TEL/AML1 and the role of TEL/AML1 testing in the treatment of childhood ALL will require additional studies.

Adolescent↗

PubMed1996

RAG mutations in human B cell-negative SCID.

Patients with human severe combined immunodeficiency (SCID) can be divided into those with B lymphocytes (B+ SCID) and those without (B- SCID). Although several genetic causes are known for B+ SCID, the etiology of B- SCID has not been defined. Six of 14 B- SCID patients tested were found to carry a mutation of the recombinase activating gene 1 (RAG-1), RAG-2, or both. This mutation resulted in a functional inability to form antigen receptors through genetic recombination and links a defect in one of the site-specific recombination systems to a human disease.

B-Lymphocytes↗

PubMed1996

Infrequent alterations of the RAR alpha gene in acute myelogenous leukemias, retinoic acid-resistant acute promyelocytic leukemias, myelodysplastic syndromes, and cell lines.

Retinoids are important regulators of cell growth and differentiation in vitro and in vivo and they exert their biologic activities by binding to nuclear retinoic acid receptors (RARs; alpha, beta, and gamma) and retinoid X receptors (RXRs; alpha, beta, and gamma). All-trans retinoic acid (RA) induces complete remission in patients with acute promyelocytic leukemia (APL) presumably by binding directly to RAR alpha of APL cells. Leukemic blasts from APL patients initially responsive to RA can become resistant to the agent. HL-60 myeloblasts cultured with RA have developed mutations of the ligand-binding region of RAR alpha and have become resistant to RA. Furthermore, insertion of an RAR alpha with an alteration in the ligand-binding region into normal murine bone marrow cells can result in growth factor-dependent immortalization of the early hematopoietic cells. To determine if alterations of the ligand binding domain of RAR alpha might be involved in several malignant hematologic disorders, the mutational status of this region (exons 7, 8, and 9) was examined in 118 samples that included a variety of cell lines and fresh cells from patients with myelodysplastic syndromes (MDS) and acute myeloid leukemias (AML), including 20 APL patients, 5 of whom were resistant to RA and 1 who was refractory to RA at diagnosis, using polymerase chain reaction-single-strand conformational polymorphism (PCR-SSCP) analysis and DNA sequencing. In addition, 7 of the 20 APLs were studied for alterations of the other coding exons of the gene (exons 2 through 6). No mutations of RAR alpha were detected. Although the sensitivity of PCR-SSCP analysis is less than 100%, these findings suggest that alterations of RAR alpha gene are rare and therefore other mechanisms must be involved in the onset of resistance to retinoids and in the lack of differentiation in disorders of the myeloid lineage.

Acute Disease↗

PubMed1996

Acute lymphoblastic leukemia of childhood: identification of two distinct regions of deletion on the short arm of chromosome 12 in the region of TEL and KIP1.

Cytogenetic analysis of acute lymphoblastic leukemia (ALL) of childhood identified nonrandom chromosomal abnormalities of the short arm of chromosome 12. The alterations include deletions that are thought to be indicative of the presence of a tumor suppressor gene that is mutated on the remaining allele. To refine further the chromosomal localization of this gene, we analyzed the loss of heterozygosity (LOH) of chromosome 12 in 100 primary ALL samples using 22 polymorphic markers and identified two distinct smallest common deleted regions on chromosome 12p13. One region is flanked by D12S77 and D12S98 and has a size of 4 cM. Twenty-six percent of informative patients showed LOH in this region. This region may contain the TEL gene. The other region is flanked by D12S269 and D12S308 including the KIP1 gene. Forty-four percent of informative patients showed LOH in this second region. Mutational analysis of KIP1 using polymerase chain reaction-single-strand conformation polymorphism analysis and Southern blot analysis showed no homozygous deletions and point mutations suggesting that the altered gene in this second region is not the KIP1. Clinical data showed that LOH of 12p was demonstrated more frequently in precursor-B ALLs (32 of 80; 40%) than in T-ALLs (1 of 20; 5%) (P = .0027). Furthermore, patients with 12p LOH were younger (P = .013), with a lower DNA index (P = .046), but they had the same survival rates at 3 years. In summary, these data suggest that two different tumor suppressor genes are on chromosome arm 12p, which act separately in the development of childhood precursor-B ALLs. One of the tumor suppressor genes is in the region the KIP1 gene, but our data suggest this gene is not abnormal. The other target is in the region of the TEL gene; and this candidate deserves further study.

Cell Cycle Proteins↗

PubMed1996

Mutational analysis of the candidate tumor suppressor genes TEL and KIP1 in childhood acute lymphoblastic leukemia.

We have shown previously that loss of heterozygosity at chromosome band 12p13 is among the most frequent genetic abnormalities identified in acute lymphoblastic leukemia (ALL) of childhood. Two known genes map within the critically deleted region of 12p: TEL, the gene encoding a new member of the ETS family of transcription factors, which is rearranged in a variety of hematological malignancies; and KIP1, the gene encoding the cyclin-dependent kinase inhibitor p27. Both genes are, therefore, excellent candidate tumor suppressor genes. In this report, we determined the exon organization of the TEL gene and performed mutational analysis of TEL and KIP1 in 33 childhood ALL patients known to have loss of heterozygosity at this locus. No mutations in either TEL or KIP1 were found; this suggest that neither TEL nor KIP1 is the critical 12p tumor suppressor gene in childhood ALL.

Base Sequence↗

PubMed1996

Molecular analysis of the cyclin-dependent kinase inhibitor family: p16(CDKN2/MTS1/INK4A), p18(INK4C) and p27(Kip1) genes in neuroblastomas.

BACKGROUND: Chromosomal abnormalities involving band 1p32, especially deletions, are frequent in neuroblastomas, indicating that a tumor suppressor gene(s) is localized at this region. The p18 gene, one of the cyclin-dependent kinase inhibitor (CDKI) genes, maps to this chromosomal region. Complexes of cyclin and cyclin-dependent kinase (CDK) play important roles in the cell cycle. CDKIs inhibit the kinase activities of these complexes and block transitions of the cell cycle. Some of the CDKI genes may be tumor suppressor genes. For example, the CDKI genes p16 and p15 are frequently deleted in various malignancies and are thought to contribute to cellular transformations. METHODS: To elucidate the importance of CDKI genes, including the p18 as well as the p16 and p27 genes in tumorigenesis of neuroblastoma, 25 neuroblastomas were analyzed for deletions by Southern blot analysis and for point mutations by polymerase chain reaction-single strand conformational polymorphism. RESULTS: No deletions, rearrangements, nor mutations were detected in these genes, however, polymorphisms reported previously were detected. CONCLUSIONS: Abnormalities, including deletions and point mutations of the p16, p18, and p27 genes, were not observed in this series of neuroblastomas. Other mechanisms to inactivate these genes, such as transcriptional or translational defects, must be analyzed. CDKI genes rarely contributed to tumorigenesis in neuroblastomas.

Base Sequence↗