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Biomedical subjects

F E Cotter

Publications and source records attributed to F E Cotter.

At least 37 records · Page 2Linked to original sources
PubMed1998

Childhood myeloproliferative disorders.

Disorders classified as paediatric myeloproliferative disorders (MPD), such as juvenile chronic myeloid leukaemia (JCML), and as paediatric myelodysplastic syndrome (MDS), are essentially diseases characterized by abnormal myeloproliferation and they share similar genetic events on chromosome 7. As such, the abnormalities of increased myeloproliferation in childhood (AIMC) should be considered under the same heading. Constitutional and other genetic factors play an essential role in children and include the NF1 gene, whereas toxic exposure is of greater importance in adults. The most common cytogenetic alteration is that of monosomy or deletion of the long arm of chromosome 7. Critical regions have been identified and mapped by fluorescence in situ hybridization (FISH). It appears that the similar critical regions on chromosome 7 are involved, and suggests that these regions may contain genes important in the pathogenesis of AIMC.

Adult↗
PubMed1998

Cytogenetic and molecular study of 32 Down syndrome families: potential leukaemia predisposing role of the most proximal segment of chromosome 21q.

Down syndrome (DS) children have a 10-20-fold increased risk of developing ALL or AML compared to non-DS children. An increased disomic homozygosity of the polymorphic DNA markers in the pericentromeric region of chromosome 21q (21q11) has repeatedly been found in DS patients with ANLL-M7 and DS-specific transient abnormal myelopoiesis (TAM), compared to the majority of DS subjects without leukaemia. Analysis of cytogenetic heteromorphisms and 26 polymorphic DNA markers from chromosome 21q showed an increased number of pericentromeric crossovers between the non-disjoined chromosomes in DS-ANLL cases (3/11), compared to DS-ALL (0/9) and DS-nonleukaemic cases (0/12). These findings are compatible with the model of disomic homozygosity of the predisposing allele of a putative pericentromeric gene, as an explanation for the high prevalence of ANLL in DS.

Chromosomes, Human, Pair 21↗
PubMed1998

Early postischemic dantrolene-induced amelioration of poly(ADP-ribose) polymerase-related bioenergetic failure in neonatal rat brain slices.

In the infant brain, ischemia-induced ionic and enzyme mechanisms may independently lead to cell death by energy depletion: resequestration of calcium mobilized from intracellular stores consumes ATP, and activated poly(ADP-ribose) polymerase (PARP) uses oxidized nicotinamide adenine dinucleotide to form polyADP-ribosyl nuclear proteins associated with DNA damage. Using 31P nuclear magnetic resonance spectroscopy, we have monitored intracellular pH and cellular energy metabolites in ex vivo neonatal rat cerebral cortex before, during, and after substrate and oxygen deprivation. In an insult that exhibited secondary energy failure and apoptosis we identified a relative 25% augmentation of high-energy phosphates at the end of recovery when the ryanodine-receptor antagonist, dantrolene, was introduced in the early (0- to 40-minute) but not late (40- to 120-minute) stage of recovery (P < 0.05). In contrast to the absence of a late dantrolene-sensitive effect, inhibition of PARP with 3-methoxybenzamide was as effective (P < 0.05) as early dantrolene, even when introduced after a 40-minute delay. The dantrolene and 3-methoxybenzamide effects on high-energy phosphates were not additive, rather the early dantrolene-sensitive effect nullified the potential 3-methoxybenzamide effect. Therefore, in this vascular-independent neonatal preparation, postischemic mobilization of calcium from intracellular stores is associated with PARP-related energy depletion. Inhibition of either of these processes confers improved postischemic bioenergetic recovery in the developing brain.

Animals↗
PubMed1997

Novel genes mapping to the critical region of the 5q- syndrome.

The 5q- syndrome is a myelodysplastic syndrome with specific hematological features and a good prognosis. Using molecular mapping techniques, we have previously defined the critical region of gene loss of the 5q- chromosome in the 5q- syndrome as the approximately 5-Mb region at 5q31-q33 flanked by the genes for FGF1 and IL12B. This region is completely represented by a series of overlapping YACs, and we are currently generating a transcription map with the aim of identifying the tumor-suppressor gene associated with the development of the 5q- syndrome. In this study two techniques have been used: first, the screening of full-length cDNA libraries with radiolabeled YACs and second, the mapping of chromosome 5-specific expressed sequence tags (ESTs) to a YAC contig. A 1-Mb YAC contig encompassing the CSF1R gene has been used to screen a fetal brain cDNA library, and this has resulted in the identification of two genes comprising one known gene previously localized to the region (ADRB2) and one known gene previously unlocalized. Six of 135 chromosome 5-specific ESTs were localized by PCR screening to the YAC contig mapping to the critical region of the 5q- syndrome. IMAGE cDNA clones for each of the six ESTs have been obtained. These seven (excluding ADRB2) newly assigned cDNA clones were subjected to further analysis. The expression patterns of each of the cDNA clones have been established in a range of human tissues, including bone marrow. Six of seven cDNAs are expressed in human bone marrow. Six of seven cDNAs have no known homology to any deposited human sequences, and one (C29) is dihydropyrimidinase-related protein-3, a member of a novel gene family. Genomic localization and expression patterns would suggest that these newly assigned cDNAs represent potential candidate genes for the 5q- syndrome.

Chromosome Deletion↗
PubMed1997

Antisense therapy for lymphomas.

The potential ability of antisense oligonucleotides to downregulate the expression of oncogenes involved in lymphoma, with minimal toxicity can be achieved. The possibility of combining antisense therapy such as BCL-2 antisense with chemotherapy will probably provide an interesting means of overcoming tumour cell resistance to chemotherapy in lymphoma and a range of other high BCL-2 expressing malignancies. As additional antisense molecules targeting oncogenes involved in lymphomas become available, it will be possible to combine them with AO to enhance their efficacy, either targeting the same gene at two sites or more a combination of genes (for example, BCL-2 and MYC in Burkitt's lymphoma). Of major importance are approaches to improve AO uptake into cells which is currently poor. Methods to improve antisense uptake into the cell are required and in addition a new generation of oligonucleotides free of the nonspecific thioate toxicities are required. AO are a dramatic new area of research and as such require much evaluation if they are to be applied maximally. Both in vitro and in vivo efficacy has been established. With care, novel therapies based on the biology of the malignant cell may be determined on a scientific basis and may help improve the treatment of patients with these diseases. Gene silencing by antisense oligonucleotides has a role to play as demonstrated in lymphomas.

Animals↗
PubMed1997

Monosomy 7 and 7q--associated with myeloid malignancy.

An association between the complete or partial loss of chromosome 7 and preleukaemic myelodysplasia or acute myeloid leukaemia has been recognized from the early days of tumour cytogenetic analysis. Detection of such abnormalities usually heralds a poor prognosis. The loss of DNA on chromosome 7 has led to speculation that tumour-suppressor genes may play a significant role in this form of leukaemogenesis, although it may be part of a multistep process. A further association with leukaemia secondary to carcinogen exposure including previous chemotherapy or a number of congenital anaemias has increased the interest in discovering the gene or genes on chromosome 7. Banded chromosome analysis has suggested that there are two broad critical regions on the long arm of chromosome 7 at bands 7q22 and 7q34-q36 that may contain the relevant genes. Initial molecular analysis has confirmed these two regions to be of significance. The advent of fluorescence in-situ hybridization techniques has facilitated some definition of the 7q22 region, with identification of candidate genes for further functional analysis. It is becoming clear that there will be more than one gene on chromosome 7 involved in the leukaemic process and with the definition of these genes it may be possible to look for associations with different phenotypes and prognosis. As for the reason for chromosome 7 showing a particular predisposition to total or partial loss we may speculate that the DNA sequence and structure may confer a 'fragility' on the chromosome. A greater understanding of the DNA structure of the long arm may provide real insight into the mechanisms of leukaemia. We would like to speculate in the long term that this could lead to the ability to screen for leukaemia susceptibility and avoidance of 'inducers' in those at risk.

Acute Disease↗
PubMed1997

t(11;18)(q21;q21) is the most common translocation in MALT lymphomas.

BACKGROUND: Low grade malignant lymphomas arising from mucosa associated lymphoid tissue (MALT) represent a distinct clinicopathological entity. The cytogenetic findings and molecular genetics of MALT lymphomas remain minimally defined. Cytogenetic studies infrequently constitute part of the diagnostic work-up of MALT lymphomas, most commonly due to small biopsy size and their extranodal localization. Only 28 MALT cases with a clonal karyotype have been published to date. A number of chromosomal abnormalities have been observed with the majority of the cases featuring trisomy of chromosome 3 which is present in up to 78% of the cases. MATERIALS AND METHODS: A total of 116 cases of MALT lymphoma were diagnosed at BCCA between 1988 and 1997. Eleven cases of pathologically confirmed MALT lymphomas were subjected to cytogenetic analysis at the time of the initial evaluation. Eight of 11 cases yielded successful cultures and the presence of a clonal karyotype using standard cytogenetic methodology. In addition, a single case of orbital MALT lymphoma with a clonal karyotype has been obtained through our consultative practice from University of Nebraska Medical Center. These nine cases of MALT lymphoma with a clonal karyotype are the subject of this report. RESULTS AND CONCLUSION: In this study we report nine cytogenetically studied MALT lymphomas, three of which feature a novel t(11;18)(q21;q21) translocation which has also been observed in five other MALT cases described in the literature. This recurrent translocation is the most common translocation associated with MALT lymphomas being present in 33% (three of nine) of our cases and 18% (five of 28) of the previously published cases. The results suggest that a potentially important gene located at one of these breakpoints may be involved in the pathogenesis of MALT lymphomas.

Adult↗
PubMed1997

Pharmacokinetics of G3139, a phosphorothioate oligodeoxynucleotide antisense to bcl-2, after intravenous administration or continuous subcutaneous infusion to mice.

An 18-mer full-phosphorothioate oligonucleotide with sequence antisense to the first six codons of the open reading frame of bcl-2 (G3139) has shown efficacy against the DoHH2 lymphoma implanted in severe combined immunodeficient mice. This study evaluated the pharmacokinetics of 35S-labeled G3139 in female BALB/c mice after single i.v. bolus administration or s.c. infusion for 1 week. After 100 microg i.v. bolus (approximately 5 mg/kg), the radioactivity was rapidly distributed and eliminated, with low blood levels 6 hr after administration. Most of the initial plasma radioactivity was protein bound (98% at 5 min). Tissue to plasma ratios were 87 for kidney, 17 for liver, 5 for spleen, 2.5 for heart and lung and 3.5 for gut. High-performance liquid chromatographic determination of G3139 showed triexponential kinetics, with alpha, beta and gamma half-lives of 5 min, 37 min and 11 hr, respectively. After 106 microg/day s.c. infusion, plasma steady state was reached by day 3, when half of the radioactivity was protein bound and 66 to 86% of the radioactivity was associated with parent drug (0.9 microg/ml). The plasma half-life of elimination for G3139 was 22 hr. Tissue to plasma ratios were similar to those after i.v. bolus administration, but accumulation was observed in all organs including bone marrow, where the levels reached were in the cytotoxic range. G3139 was metabolized to at least three different products, all observed in plasma, liver and kidney. Two metabolites eluted before the parent compound and one after the parent compound. There was greater degradation in the liver 6 hr after i.v. administration than at 24 hr, 48 hr, 3 days and 7 days after s.c. administration. In the kidney, most radioactivity was G3139. All degradation products were found in the urine but only traces of parent drug were eliminated. After both routes of administration, most of the radioactivity was eliminated in the urine and to a lesser extent in the feces. Significantly more radioactivity was excreted in the urine after i.v. bolus, compared with s.c. infusion (33% on day 1 and 55% by day 3 for i.v. vs. 7.2% on day 1 and 12.9% by day 3 for s.c.). These data show that s.c. infusion resulted in less excretion and metabolism of the administered dose.

Animals↗
PubMed1996

Molecular definition of a narrow interval at 7q22.1 associated with myelodysplasia.

Chromosome 7 translocations, deletions, or monosomy are associated with myelodysplasia (MDS) and acute myeloid leukemia both in children and adults. These chromosomal anomalies represent one of the most common cytogenetic abnormalities associated with these diseases and usually herald a poor prognosis. In this study two cosmid DNA probes that mapped to 7q22.1 and were known to be separated by approximately 500 kb were identified to flank the proximal inversion breakpoint in a patient carrying a constitutional inversion (7q22.1-34) associated with MDS. A yeast artificial chromosome (YAC) clone that encompassed the two cosmids was identified and shown to span the breakpoint. Fluorescence in situ hybridization was then used to analyze six additional patients with myelodysplasia and chromosomal rearrangements of the 7q22 region (three patients had translocations and three carried deletions). The breakpoint in one of the patients was found to be contained within the same YAC clone that spanned the inversion breakpoint. Moreover, this same interval was determined to be absent in all three patients with chromosomal deletions. These results suggest that this segment of DNA on chromosome 7q22.1 may contain specific gene(s) that have a significant role in myeloid malignancies.

Cell Line, Transformed↗
PubMed1996

Anti-sense and gene therapy approaches to the treatment of lymphomas.

The availability of molecular genetic technology has opened up a large range of potential strategies for the treatment of lymphoma. In the immediate future it is likely that these techniques will be of most use in the evaluation of procedures such as purging, ex vivo expansion of haemopoietic progenitors and adoptive immunotherapy. On the horizon however are strategies such as anti-sense, immune gene therapy and stem cell protection which may prove valuable adjuncts to our existing therapeutic armoury. The pace of developments in this field is such that long-term predictions are unlikely to be accurate but it seems certain that this whole area will continue to grow rapidly.

Genetic Therapy↗
PubMed1995

BCL-2 expression by leukaemic blasts in a SCID mouse model of biphenotypic leukaemia associated with the t(4;11)(q21;q23) translocation.

Acute leukaemia of infancy is associated with abnormalities at chromosome band 11q23, and has a poor prognosis. The gene involved. Mixed Lineage Leukaemia (MLL), has been identified and has the characteristics of a transcription factor. The BCL-2 gene responsible for blocking of programmed cell death is highly expressed in a number of haematological malignancies, both with and without the t(14;18) translocation. Those without the translocation include acute lymphoblastic leukaemia (ALL), acute myeloid leukaemia (AML) and chronic lymphocytic leukaemia (CLL). In these diseases the BCL-2 protein is implicated in drug resistance to apoptosis-inducing chemotherapeutic agents. High BCL-2 expression is also associated with autonomous growth of leukaemic blasts in culture and predicts a poor prognosis. The SEM cell line, established using blood lymphoblasts from a 5-year-old girl in first relapse with t(4;11) ALL, expresses lymphoid (CD19) and myeloid (CD13) cell surface markers. In cell culture, a subpopulation of cells (< 30%) express the BCL-2 protein. A reproducible model of true biphenotypic leukaemia in the SCID mouse has been established using the SEM-K2 cell line (a subclone of the SEM cell line). Between 5 and 50 million cells injected intravenously (i.v.) produce complete replacement of the murine bone marrow by day 30, associated with blood lymphoblastosis and infiltration of the spleen. No tumour masses were seen. Fluorescence in situ hybridization (FISH) analysis of the cell line and blood from the SCID-human (SCID-hu) chimaera has confirmed the presence of the t(4;11). Reverse transcriptional-polymerase chain reaction (RT-PCR) reveals that the breakpoint lies between exons 7 and 8 of the MLL-1 gene on chromosome 11 (the main breakpoint region). A further translocation, t(7;13), has been identified. Fluorescent antibody cell sorter (FACS) analysis of tumour material recovered from the SCID-hu model confirms expression of CD19 and CD13 identical to that of the cell line. In addition, BCL-2 expression in SCID-hu marrow is now seen in the majority of tumour cells. BCL-2 expression appears to confer a survival advantage to the blast cells in vivo. This reproducible model of biphenotypic leukaemia suggests that BCL-2 expression may play a role in leukaemogenesis. The model is suitable for the investigation of gene-targeted therapy, including antisense oligonucleotides, directed towards the MLL and BCL-2 genes.

Animals↗
PubMed1995

Detection of chromosome 11 alterations in blood and bone marrow by interphase cytogenetics in mantle cell lymphoma.

The t(11;14)(q13;q32) translocation is a consistent chromosome change in mantle cell lymphomas. This study investigates the application of fluorescent in situ hybridization (FISH) with chromosome painting probes for interphase cytogenetic analysis in patients with mantle cell lymphomas. Chromosome 11 paints have been able to show splitting of the chromosome signal consistent with the t(11;14) translocation in interphase cells from bone marrow and blood of patients with mantle cell lymphomas. These include some in clinical remission. The chromosome probes conjugated with fluorescent molecules are hybridized with patient's DNA allowing the easy detection of chromosome 11 abnormalities with fluorescent-light microscopes. Interphase FISH has a higher sensitivity and is quicker than standard metaphase cytogenetics. This may be beneficial in rapid detection of chromosome 11 abnormalities, assisting in the diagnosis of mantle cell lymphomas. In addition, detection of a clonal population of cells is possible.

Bone Marrow↗
PubMed1994

Detection of cells bearing the t(14;18) translocation following myeloablative treatment and autologous bone marrow transplantation for follicular lymphoma.

PURPOSE: To use the polymerase chain reaction (PCR) technique for molecular assessment of the results of myeloablative treatment of follicular lymphoma with autologous bone marrow transplantation. PATIENTS AND METHODS: Seventy-six patients with follicular or transformed follicular lymphoma were treated with cyclophosphamide 60 mg/kg x 2 and total-body irradiation 12 Gy, supported by autologous bone marrow transplantation. The bone marrow mononuclear cell fraction was treated in vitro with CD20 monoclonal antibody and baby rabbit complement. The PCR technique was used to identify 50 patients with amplifiable t(14; 18) translocations in biopsy material from lymph nodes or bone marrow infiltrated by lymphoma. RESULTS: Following treatment of the harvested bone marrow in vitro, 29 samples were tested by PCR to assess the efficacy of purging. In 25 cases, the same t(14; 18) sequences were amplified as from the patients' original biopsies, while in four cases, the marrow became PCR-negative. Three of the four patients treated with PCR-negative marrow subsequently developed recurrent lymphoma, compared with 11 of 25 in the PCR-positive group. Bone marrow and peripheral-blood mononuclear cell samples from 27 patients were studied during the follow-up period. All but one had the presence of the lymphoma-related t(14; 18) clone detectable by PCR and confirmed by direct sequencing from at least one sample between 3 months and 7 years after reinfusion of the bone marrow. With a median follow-up duration of 3 years, 13 patients developed recurrent disease, 13 remained in remission with the t(14; 18) still detectable, and one died of acute myeloid leukemia. CONCLUSION: This form of therapy does not eliminate the lymphoma-related t(14; 18)-bearing clone of cells, although the significance of its continued presence is uncertain. Improved methods for both treatment of the bone marrow in vitro and treatment of the lymphoma in vivo are required.

Adult↗
PubMed1994

Antisense oligonucleotides suppress B-cell lymphoma growth in a SCID-hu mouse model.

The t(14;18) translocation is found in the majority follicular lymphomas and some high grade B-cell lymphomas. This is results in deregulation of the BCL-2 gene and appears to play a role in oncogenesis. Various numbers of cells from a cell line derived spontaneously from a patient with B-cell lymphoma bearing the t(14;18) translocation and negative for the Epstein-Barr virus (EBV) were injected by IP, IV, and SC routes into SCID mice. The mice developed lymphoma bearing the t(14;18) translocation with as few as 5 x 10(6) cells within 28 days. This was determined by histological examination. The higher the cell inoculation the more rapidly the lymphoma developed. Engraftment of the tumour cells was determined by PCR for the t(14;18) breakpoint region on peripheral blood samples and could be detected prior to development of overt lymphoma. Having established a lymphoma model the cells were treated with antisense oligonucleotides to the first open reading frame of the BCL-2 gene prior to inoculation of the SCID mice. Control treatments with sense and nonsense oligonucleotides was also performed. At 28 days the sense, nonsense and untreated cell SCID mice had developed lymphoma, however, the antisense treated group failed to develop lymphoma. The findings demonstrate the modelling of B-cell lymphoma bearing the t(14;18) translocation and the ability to modify the lymphoma process with the use of antisense oligonucleotides to the BCL-2 gene. Reduction of the BCL2 protein suppresses the oncogenic potential of these lymphoma cells confirming that it plays an essential role in the development of malignancy.

Animals↗