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Bouffler SD, Finnon P, Blasco MA, Ainsbury E. A possible role for telomerase RNA and telomere length in global mitotic recombination. Cytogenet Genome Res 2009; 122:292-6. [PMID: 19188698 DOI: 10.1159/000167815] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/27/2008] [Indexed: 11/19/2022] Open
Abstract
Telomeres are specialised structures at the ends of mammalian chromosomes with many unique properties. Recombinational events at telomeres are more frequent than in the remainder of the genome by several orders of magnitude. This study examined the influence of telomerase status and telomere length on genome-wide recombination assessed by genomic sister chromatid exchange (G-SCE). Telomerase deficiency per se appears to increase G-SCE frequencies in splenocytes but as telomeres shorten through subsequent generations of mTerc(-/-) mice this increase is progressively lost. Telomerase status and telomere length also influences the induction of G-SCE by UV light. Even when mitotic recombination is affected by PARP deficiency, mTerc and telomere length interact to further affect G-SCE frequencies. Taken together the data presented here demonstrate that telomerase status and telomere length can affect recombination frequencies genome-wide.
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Affiliation(s)
- S D Bouffler
- Health Protection Agency, Radiation Protection Division, Chilton, Didcot, UK.
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2
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Badie C, Dziwura S, Raffy C, Tsigani T, Alsbeih G, Moody J, Finnon P, Levine E, Scott D, Bouffler S. Aberrant CDKN1A transcriptional response associates with abnormal sensitivity to radiation treatment. Br J Cancer 2008; 98:1845-51. [PMID: 18493234 PMCID: PMC2410125 DOI: 10.1038/sj.bjc.6604381] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Normal tissue reactions to radiation therapy vary in severity among patients and cannot be accurately predicted, limiting treatment doses. The existence of heritable radiosensitivity syndromes suggests that normal tissue reaction severity is determined, at least in part, by genetic factors and these may be revealed by differences in gene expression. To test this hypothesis, peripheral blood lymphocyte cultures from 22 breast cancer patients with either minimal (11) or very severe acute skin reactions (11) have been used to analyse gene expression. Basal and post-irradiation expression of four radiation-responsive genes (CDKN1A, GADD45A, CCNB1, and BBC3) was determined by quantitative real-time PCR in T-cell cultures established from the two patient groups before radiotherapy. Relative expression levels of BBC3, CCNB1, and GADD45A 2 h following 2 Gy X-rays did not discriminate between groups. However, post-irradiation expression response was significantly reduced for CDKN1A (P<0.002) in severe reactors compared to normal. Prediction of reaction severity of approximately 91% of individuals sampled was achieved using this end point. Analysis of TP53 Arg72Pro and CDKN1A Ser31Arg single nucleotide polymorphisms did not show any significant association with reaction sensitivity. Although these results require confirmation and extension, this study demonstrates the possibility of predicting the severity of acute skin radiation toxicity in simple tests.
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Affiliation(s)
- C Badie
- Radiation Effects Department, Health Protection Agency, Centre for Radiation Chemical and Environmental Hazards, Radiation Protection Division, Chilton, Didcot, Oxfordshire OX11 ORQ, UK.
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3
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Sims AH, Finnon P, Miller CJ, Bouffler SD, Howell A, Scott D, Clarke RB. TPD52 and NFKB1 gene expression levels correlate with G2 chromosomal radiosensitivity in lymphocytes of women with and at risk of hereditary breast cancer. Int J Radiat Biol 2007; 83:409-20. [PMID: 17487680 DOI: 10.1080/09553000701317366] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
PURPOSE To evaluate a transcriptomic approach to identify healthy women at increased risk of breast cancer due to G2-radiosensitivity and look at transcripts that are differentially expressed between individuals. MATERIALS AND METHODS We perform the first study to assess the association of G2 radiosensitivity with basal gene expression in cultured T-lymphocytes from 11 women with breast cancer and 12 healthy female relatives using Affymetrix GeneChips. RESULTS Transcripts associated with radiosensitivity and breast cancer risk were predominantly involved in innate immunity and inflammation, such as interleukins and chemokines. Genes differentially expressed in radiosensitive individuals were more similarly expressed in close family members than in un-related individuals, suggesting heritability of the trait. The expression of tumour protein D52 (TPD52), a gene implicated in cell proliferation, apoptosis, and vesicle trafficking was the most strongly correlated with G2 score while nuclear factor (kappa)-B (NFKB1) was highly inversely correlated with G2 score. NFKB1 is known to be activated by irradiation and its inhibition has been previously shown to increase radiosensitivity. CONCLUSIONS Gene expression analysis of lymphocytes may provide a quantitative measure of radiation response potential and is a promising marker of breast cancer susceptibility.
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Affiliation(s)
- A H Sims
- Breast Biology Group, Paterson Institute for Cancer Research, University of Manchester, UK.
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4
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Darakhshan F, Badie C, Moody J, Coster M, Finnon R, Finnon P, Edwards AA, Szluinska M, Skidmore CJ, Yoshida K, Ullrich R, Cox R, Bouffler SD. Evidence for complex multigenic inheritance of radiation AML susceptibility in mice revealed using a surrogate phenotypic assay. Carcinogenesis 2005; 27:311-8. [PMID: 16093251 DOI: 10.1093/carcin/bgi207] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The mapping of genes which affect individual cancer risk is an important but complex challenge. A surrogate assay of susceptibility to radiation-induced acute myeloid leukaemia (AML) in the mouse based on chromosomal radiosensitivity has been developed and validated. This assay was applied to the mapping of radiation-induced AML risk modifier loci by association with microsatellite markers. A region on chromosome (chr) 18 with strong association is identified and confirmed by backcross analysis. Additional loci on chrs 8 and 13 show significant association. A key candidate gene Rbbp8 on chr18 is identified. Rbbp8 is shown to be upregulated in response to X-irradiation in the AML sensitive CBA strain but not AML resistant C57BL/6 strain. This study demonstrates the strength of utilizing surrogate endpoints of cancer susceptibility in the mapping of mouse loci and identifies additional loci that may affect radiation cancer risk.
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Affiliation(s)
- F Darakhshan
- Radiation Effects Department, Health Protection Agency, Radiation Protection Division, Chilton, Didcot, Oxfordshire, OX11 0RQ, UK
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Di Giorgio M, Edwards AA, Moquet JE, Finnon P, Hone PA, Lloyd DC, Kreiner AJ, Schuff JA, Tajal MR, Vallerga MB, López FO, Burlón A, Debray ME, Valda A. Chromosome aberrations induced in human lymphocytes by heavy charged particles in track segment mode. Radiat Prot Dosimetry 2004; 108:47-53. [PMID: 14974604 DOI: 10.1093/rpd/nch012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Human blood was irradiated with accelerated ions: 20 MeV 4He, 425 MeV 12C and 1480 MeV and 996 MeV 16O. For each ion, the blood was exposed to a range of doses as thin specimens in the track segment mode, so that irradiations took place at nearly constant LETs of 31.4, 61, 52 and 69 keV microm(-1), respectively. Lymphocytes were cultured to the first in vitro metaphase, analysed for chromosomal damage and the dicentric aberration frequencies fitted to the linear quadratic model of dose-response. For these high LET radiations, the linear (alpha) yield coefficient predominated and increased with LET, at least up to 60 keV microm(-1). Apart from the 996 MeV oxygen ions, the data indicated the presence of a quadratic (beta) coefficient, statistically consistent with values obtained with low LET radiations. However, the associated uncertainties on the measured beta values were large, illustrating the general problem that beta is more difficult to measure against a dominating and ever-increasing alpha term. The existence or otherwise of a beta component of the dose-response at these radiation qualities has important consequences for modelling mechanisms of aberration induction by radiation.
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Affiliation(s)
- M Di Giorgio
- Autoridad Regulatoria Nuclear, Av. Del Libertador 8250, CP: C1429BNP, Ciudad de Buenos Aires, Argentina
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6
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Bryant PE, Gray L, Riches AC, Steel CM, Finnon P, Howe O, Kesterton I, Vral A, Curwen GB, Smart V, Tawn EJ, Whitehouse CA. The G2 chromosomal radiosensitivity assay. Int J Radiat Biol 2002; 78:863-6. [PMID: 12428927 DOI: 10.1080/09553000210144484] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Although requiring stringent experimental conditions to achieve good reproducibility, the G2 assay has potential as a sensitive marker for cancer susceptibility, and is particularly useful in population studies. Immediate culture of blood is preferable, but overnight storage of blood either at ambient temperature or at 4 degrees C does not appear significantly to affect G2 scores. Transport of blood may lead to additional variability in assay results and should be well controlled. Although reproducibility is generally good, G2 scores on blood from certain individuals appear to show significant variability in repeat samples. Thus, determination of an individual's radiosensitivity may require multiple assays on different occasions. While it is recognized that the distinction between aligned and mis-aligned discontinuities has no scientific basis, some laboratories have decided for the purpose of record-keeping to score all aligned discontinuities as gaps, and mis-aligned discontinuities as breaks. In all cases the final G2 score should comprise the sum of all gaps and breaks.
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Affiliation(s)
- P E Bryant
- School of Biology, University of St Andrews, Scotland, UK.
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Finnon P, Wong HP, Silver AR, Slijepcevic P, Bouffler SD. Long but dysfunctional telomeres correlate with chromosomal radiosensitivity in a mouse AML cell line. Int J Radiat Biol 2001; 77:1151-62. [PMID: 11747540 DOI: 10.1080/09553000110075220] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
PURPOSE To compare the chromosomal radiosensitivity of C3H mouse acute myeloid leukaemia (AML) cell lines 7926 and 8709 and to investigate the mechanistic basis of the radiosensitivity observed in 7926. MATERIALS AND METHODS Yields of chromosome aberrations following X-irradiation were determined in Giemsa-stained metaphases. Cell cycle phase distributions were determined by BrdU incorporation and microscopy, apoptosis was assessed by caspase assays. Telomerase activity (TRAP assay), telomere length (Q-FISH and Southern blotting) and telomere function (Robertsonian-like fusion formation) were also examined. The expression levels of telomerase components, telomerase regulators and DNA PKcs were determined on Northern blots. RESULTS A total of 4.5-7.6-fold elevated chromosome aberration yields were found in 7926 by comparison with 8709 3-24h after 0.5 and 1 Gy X-ray exposure. This difference could not be accounted for by differences in chromatid break-rejoining rates, cell cycle phase distribution or the induction of apoptosis. Telomeres and telomerase were dysfunctional in 7926. However, average telomere length was approximately two-fold greater than in 8709. CONCLUSION Defective telomere function in 7926 correlates with chromosomal radiosensitivity. This implicates telomere function in addition to telomere length as a determinant of chromosomal radiosensitivity.
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MESH Headings
- Animals
- Apoptosis
- Blotting, Northern
- Blotting, Southern
- Chromosomes/radiation effects
- Dose-Response Relationship, Drug
- Dose-Response Relationship, Radiation
- Electrophoresis, Agar Gel
- In Situ Hybridization, Fluorescence
- Leukemia, Myeloid, Acute/radiotherapy
- Metaphase
- Mice
- Mice, Inbred C3H
- Mitosis
- Oligonucleotides/pharmacology
- Phenotype
- Radiation Tolerance
- S Phase
- Sequence Analysis, DNA
- Telomerase/metabolism
- Time Factors
- Tumor Cells, Cultured
- X-Rays
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Affiliation(s)
- P Finnon
- National Radiological Protection Board, Chilton, Didcot X11 ORQ, UK.
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8
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Finnon P, Silver AR, Bouffler SD. Upregulation of telomerase activity by X-irradiation in mouse leukaemia cells is independent of Tert, Terc, Tnks and Myc transcription. Carcinogenesis 2000; 21:573-8. [PMID: 10753188 DOI: 10.1093/carcin/21.4.573] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
X-irradiation of two mouse myeloid leukaemia cell lines was found to lead to increased telomerase activities. Maximal increases in activity at 24 h post-irradiation were approximately three times control unirradiated cell levels. These maxima were reached at between 3-5 Gy depending upon cell line. Peak activity was reached at 8h, remained elevated to 24 h and returned to control levels by 48 h. In contrast, X-irradiation did not activate telomerase in a telomerase-negative human fibroblast line, while in cultured normal mouse bone marrow cells irradiation appeared to reduce activities. No simple relationship between radiation-induced increases in telomerase activity in the myeloid leukaemia lines and the proportions of cells in the S or M phases of the cell cycle was apparent. Radiation-induced increases in activity were significantly reduced by inhibitors of transcription (actinomycin D, alpha-amanatin) and protein synthesis (cycloheximide). These data are consistent with two possibilities: (i) X-irradiation leads to increased transcription and/or translation of a component of telomerase, thus increasing activities; or (ii) X-irradiation induces the transcription of a positive regulator of telomerase activity. Northern blot analysis did not indicate that transcription of mTert, the catalytic subunit of telomerase, or mTerc, the RNA component, was elevated after irradiation. Similarly, no significant changes in the expression of Myc or Tnks, the tankyrase gene, two suspected telomerase regulators, were detected. These data are therefore consistent with the induction by X-irradiation of a positive regulator of telomerase activity other than Tnks or Myc or the core protein and RNA components of the enzyme.
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Affiliation(s)
- P Finnon
- Radiation Effects Department, National Radiological Protection Board, Chilton, Didcot, Oxon OX11 ORQ, UK
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9
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Finnon P, Moquet JE, Edwards AA, Lloyd DC. The 60Co gamma ray dose-response for chromosomal aberrations in human lymphocytes analysed by FISH; applicability to biological dosimetry. Int J Radiat Biol 1999; 75:1215-22. [PMID: 10549597 DOI: 10.1080/095530099139368] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
PURPOSE To investigate the in vitro dose-response for 60Co irradiated human lymphocytes assayed by FISH, and to consider how this may be applied to retrospective dosimetry. METHOD Blood was irradiated with doses in the range 0.25-4.0 Gy. Cultured lymphocytes were scored for all stable and unstable aberrations involving painted chromosomes 2, 3 and 5 and, in addition, all unstable aberrations in the counterstained chromosomes. A pancentromeric probe was included. RESULTS The relative numbers of painted and full genome dicentrics agreed well with the Lucas hypothesis for calculating genome equivalence. The involvement of each painted chromosome in exchanges agreed with their relative arm lengths. The dose-response relationship fitted well to the linear quadratic model; Y=(0.9 x 10(-2))D+(6.5 x 10(-2))D2 where D is the dose in Gy for the incidence Y, of all one plus two-way translocations in all cells corrected for genome equivalence. Complex rearrangements also became more frequent with increasing dose. A correlation was noted between the distributions of dicentrics and translocations among the cells and this was entirely due to complexes. CONCLUSIONS For retrospective dosimetry it is recommended to use an in vitro dose-response for apparently simple translocations in stable (Cs) cells. To date, acute linear yield coefficients from FISH data carry statistical uncertainties too large for useful application to retrospective dosimetry of persons exposed to chronic or low doses. As an interim measure it is suggested that one may derive a linear term from full genome dicentrics corrected by a factor representing the translocation to dicentric ratio.
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Affiliation(s)
- P Finnon
- National Radiological Protection Board, Chilton, Didcot, Oxon, UK
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10
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Silver A, Moody J, Dunford R, Clark D, Ganz S, Bulman R, Bouffler S, Finnon P, Meijne E, Huiskamp R, Cox R. Molecular mapping of chromosome 2 deletions in murine radiation-induced AML localizes a putative tumor suppressor gene to a 1.0 cM region homologous to human chromosome segment 11p11-12. Genes Chromosomes Cancer 1999; 24:95-104. [PMID: 9885975] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023] Open
Abstract
Radiation-induced acute myeloid leukemias (AMLs) in the mouse are characterized by chromosome 2 deletions. Previous studies showed that a minimal deleted region (mdr) of approximately 6.5 cM is lost from one homologue in chromosome 2-deleted AMLs. An AML tumor suppressor gene is proposed to map within this mdr. In this study, we refine the mdr to a I cM interval between markers D2Mit126 and D2Mit185 by microsatellite analysis of 21 primary radiation-induced F I AMLs. The construction of a partial yeast artificial chromosome (YAC) contig spanning the mdr and the location of six known genes indicated that the 1 cM mdr is homologous to human 11p11-12, a region implicated in some human AMLs. Screening of five cell lines derived from primary radiation-induced AMLs for homozygous loss of microsatellites and genes mapping within the mdr revealed loss of both copies of the hemopoietic tissue-specific transcription factor Sfpi1(PU.1/Spi1) in one cell line. Studies of primary and F1 AMLs failed to implicate Sfpi1 as the AML tumor suppressor gene. YAC contig construction, together with data suggesting that the critical gene flanks Sfpi1, represents significant progress toward identifying an AML tumor suppressor gene.
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MESH Headings
- Animals
- Chromosome Deletion
- Chromosome Mapping/methods
- Chromosomes, Artificial, Yeast
- Chromosomes, Human, Pair 11/genetics
- Contig Mapping
- Crosses, Genetic
- Genes, Tumor Suppressor/genetics
- Humans
- Leukemia, Myeloid, Acute
- Mice
- Mice, Inbred C57BL
- Mice, Inbred CBA
- Microsatellite Repeats/genetics
- Sequence Homology, Nucleic Acid
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Affiliation(s)
- A Silver
- Radiation Effects Department, National Radiological Protection Board, Chilton, Oxfordshire, England.
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11
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Lloyd DC, Finnon P, Edwards AA, Haines JW. Chromosome aberrations in Syrian hamsters following very low radiation doses in vivo. Mutat Res 1997; 377:63-8. [PMID: 9219580 DOI: 10.1016/s0027-5107(97)00059-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
This paper addresses a report of a large increase (approximately 6- to 11-fold) in chromosome aberrations in lymphocytes of persons in Salzburg attributed to their exposure to fallout from the Chernobyl cloud. Their additional exposure, approximately 0.3 mGy in 1 year, comprised about a 30% increase in their normal background radiation dose. The report has attracted considerable attention because, if correct, it seriously challenges assumptions of linearity in the low-dose response for chromosomal damage and, by implication, the linear, no-threshold hypothesis for risk of induced cancer. An experiment has been carried out with Syrian hamsters treated with caesium-137 to produce a range of doses comparable with those calculated for the persons in Salzburg. No significant elevation in lymphocyte aberration yields was found in the hamsters, thus arguing against the conclusions of the Salzburg study.
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Affiliation(s)
- D C Lloyd
- National Radiological Protection Board, Chilton, Oxon, UK
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12
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Finnon P, Lloyd DC, Edwards AA. Fluorescence in situ hybridization detection of chromosomal aberrations in human lymphocytes: applicability to biological dosimetry. Int J Radiat Biol 1995; 68:429-35. [PMID: 7594969 DOI: 10.1080/09553009514551391] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Human lymphocytes in G0 have been irradiated with X-ray doses from 0 to 4.0 Gy. Metaphase chromosomes 2, 3 and 5 and all centromeres were painted using fluorescence in situ hybridization (FISH) probe libraries. Dicentrics, centric rings and acentrics in the whole genome as well as translocations involving the painted chromosomes were recorded. The translocations were subdivided as complete or incomplete. Interstitial insertions and inversions were also noted. The observations were also recorded according to the Protocol for Aberration Identification and Nomenclature Terminology (PAINT) system of scoring. Given that the painted chromosomes comprise 20.4% of the genome it was found that the yield of bicoloured dicentrics was consistent with the yield of dicentrics in the whole genome. The yield of radiation-induced translocations was not significantly higher than that of bicoloured dicentrics. Of the translocations, 60% were complete and it was concluded that the majority of dicentrics and translocations are complete exchanges. Chromosome 5 took part in exchanges marginally more commonly than its length suggests, but it is not known if this is a property of the chromosome or whether it is a donor-dependent observation. The PAINT system of recording rearrangements was examined and the suggested numerical interpretation of this nomenclature was considered to be unsuitable for use in the estimation of dose for cases of accidental overexposure.
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Affiliation(s)
- P Finnon
- National Radiological Protection Board, Chilton, Didcot, UK
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13
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Lloyd DC, Edwards AA, Prosser JS, Finnon P, Moquet JE. In vitro induction of chromosomal aberrations in human lymphocytes, with and without boron 10, by radiations concerned in boron neutron capture therapy. Br J Radiol 1988; 61:1136-41. [PMID: 3219494 DOI: 10.1259/0007-1285-61-732-1136] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
A beam consisting of mainly 24 keV neutrons has been constructed for radiobiological studies to evaluate the potential of these particles for treating deep tumours by the boron capture reaction. The induction of chromosomal aberrations in human lymphocytes in vitro was examined and a linear dose effect with a relative biological effectiveness similar to fission neutrons was obtained. For samples placed at depths in a plastic phantom the aberration yields declined with depth at a rate matching the fall in the sum of dose due to proton recoils and neutron capture in nitrogen 14. The presence of boron 10 at 30 micrograms ml-1 did not affect the aberration yield. By using the mixed sample method, the probability of interphase death or mitotic delay in cells crossed by an alpha particle or lithium-7 ion produced in the boron capture reaction was shown to be close to 1.0. Thus these cells are prevented from coming to mitosis in culture. The implications for boron capture therapy are that this filtered beam has a "high LET" effect which could lead to poor normal tissue sparing. However there may be a significant therapeutic advantage due to a high probability of killing tumour cells that have incorporated boron 10.
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Affiliation(s)
- D C Lloyd
- National Radiological Protection Board, Chilton, Didcot, Oxfordshire
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14
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Edwards AA, Lloyd DC, Prosser JS, Finnon P, Moquet JE. Chromosome aberrations induced in human lymphocytes by 8.7 MeV protons and 23.5 MeV helium-3 ions. Int J Radiat Biol Relat Stud Phys Chem Med 1986; 50:137-45. [PMID: 3013793 DOI: 10.1080/09553008614550511] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
This paper describes the irradiation of thin samples of blood with 8.7 MeV protons and 23.5 MeV helium-3 ions in the track segment mode. Chromosome aberrations in human lymphocytes have been scored. The relationship between dicentric yield and dose in Gy was Y = 0.044 D + 0.058 D2 for protons and Y = 0.394 D for helium ions. These results are compared with data from other laboratories using protons and an attempt is made to reconcile differences. An unexpected observation was that the ratio of the linear coefficients for helium ions and protons was about 9 whereas the ratio of the l.e.t. values was 4.5. This disagrees with current theory which predicts that the linear coefficients should be proportional to l.e.t. Possible sources of error in our experiments are discussed but do not adequately account for the discrepancies.
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Abstract
The Cytoscan 110 metaphase finder has been tested with cultures of human peripheral blood lymphocytes prior to its introduction into routine use for the analysis of radiation-induced chromosomal damage. Cells of varying quality and density of distribution on slides, stained with orcein or Giemsa, were examined by the same technician using the Cytoscan and a conventional microscope. The Cytoscan was able to locate rapidly (less than 2 min) virtually all metaphases known to be present and with an acceptably low rate of false positives. The presence of mixtures of FPG-stained first- and second-division spreads did not reduce its efficiency in metaphase finding. The instrument automatically divides the objects that it locates into 4 quality ranks and this was very effective in separating good metaphases, suitable for high-magnification scoring, from unscorable spreads and debris. With cultures of X-irradiated blood it was shown that the criteria by which the Cytoscan locates metaphases and ranks their appearance do not introduce bias in the yields of dicentric and other unstable chromosome-type aberrations.
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16
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Lloyd DC, Saunders RD, Finnon P, Kowalczuk CI. No clastogenic effect from in vitro microwave irradiation of G0 human lymphocytes. Int J Radiat Biol Relat Stud Phys Chem Med 1984; 46:135-41. [PMID: 6332088 DOI: 10.1080/09553008414551211] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Specimens of human blood were exposed at specific energy absorption rates of 104 or 193 W kg-1 to 2.45 GHz microwave radiation at temperatures below 36 degrees C. Cultured lymphocytes were examined for induced unstable chromosome and chromatid aberrations and sister chromatid exchanges. The amount of chromosome damage observed did not exceed that found in controls.
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