Biomedical subjects

M Bauchinger

Publications and source records attributed to M Bauchinger.

At least 19 recordsLinked to original sources

PubMed2001

Clonal chromosomal aberrations in simian virus 40-transfected human thyroid cells and in derived tumors developed after in vitro irradiation.

In vitro model cell systems are important tools for studying mechanisms of radiation-induced neoplastic transformation of human epithelial cells. In our study, the human thyroid epithelial cell line HTori-3 was analyzed cytogenetically following exposure to different doses of alpha- and gamma-irradiation and subsequent tumor formation in athymic nude mice. Combining results from G-banding, comparative genomic hybridization, and spectral karyotyping, chromosome abnormalities could be depicted in the parental line HTori-3 and in nine different HTori lines established from the developed tumors. A number of chromosomal aberrations were found to be characteristic for simian virus 40 immortalization and/or radiation-induced transformation of human thyroid epithelial cells. Common chromosomal changes in cell lines originating from different irradiation experiments were loss of 8q23 and 13cen-q21 as well as gain of 1q32-qter and 2q11.2-q14.1. By comparison of chromosomal aberrations in cell lines exhibiting a different tumorigenic behavior, cytogenetic markers important for the tumorigenic process were studied. It appeared that deletions on chromosomes 9q32-q34 and 7q21-q31 as well as an increased copy number of chromosome 20 were important for the tumorigenic phenotype. A comparative breakpoint analysis of the marker chromosomes found and those observed in radiation-induced childhood thyroid tumors from Belarus revealed a coincidence for a number of chromosome bands. Thus, the data support the usefulness of the established cell system as an in vitro model to study important steps during radiation-induced malignant transformation in human thyroid cells.

Animals↗

PubMed2001

Technical report: application of the Metafer2 fluorescence scanning system for the analysis of radiation-induced chromosome aberrations measured by FISH-chromosome painting.

The Metafer2 fluorescence scanning system was used for routine analysis of radiation-induced exchange aberrations measured by fluorescence in situ hybridisation (FISH) chromosome painting in human peripheral lymphocytes. The system enables a rapid and unbiased fully-automated finding and image acquisition of fluorescently stained metaphase spreads. The chromosome aberration analysis is performed interactively from stored digitised processed gallery images, presented on a screen. Appropriate software image filters are available to further improve these pictures by background correction, noise reduction and fluorescence signal enhancement. Data sets generated by computer-assisted and manual scoring of radiation-induced reciprocal translocations (2B) and total 2B (2B+related 'one-way' types) or complete dicentrics (2A) and total 2A (2A+related 'one-ways') involving painted target chromosomes 2, 3 or 4 were compared and no significant differences were found.A linear-quadratic dose-response curve for total translocations (2B+'one-ways'+complex-derived types) based on computer-assisted analysis of 27,741 metaphases with chromosome 4 painting was compared to a curve obtained earlier for manually scored translocations in a set of target chromosomes 1, 4 and 12. After extrapolation to the whole genome, no significant difference between both curves was found. From our results it can be derived that computer-assisted aberration analysis using the Metafer2 system is a reliable alternative to manual analysis. Since time saving for computer-assisted translocation analysis is about 50% compared to manual scoring, this system is highly promising for a practical application in retrospective biodosimetry of human radiation exposure.

Adult↗

PubMed2001

Chromosomal changes during development and progression of prostate adenocarcinomas.

Chromosomal copy number changes were investigated in 16 prostate carcinomas, 12 prostatic intraepithelial neoplasias (PIN; 4 low-grade and 8 high-grade) adjacent to the invasive tumour areas, and 5 regional lymph node metastases. For this purpose, comparative genomic hybridization (CGH) was performed and a copy number karyotype for each histomorphological entity was created. CGH on microdissected cells from non-neoplastic glands was carried out on 3 different cases to demonstrate the reliability of the overall procedure. None of the non-neoplastic tissue samples revealed chromosome copy number changes. In PIN areas, chromosomal imbalances were detected on chromosomes 7, 8q, Xq (gains), and on 4q, 5q, 8p, 13q and 18q (losses). In the primary tumours, recurrent (at least 25% of cases) gains on chromosomes 12q and 15q, and losses on 2q, 4q, 5q, Xq, 13q and 18q became apparent. Losses on 8p and 6q as well as gains on 8q and of chromosome 7 were also detected at lower frequencies than previously reported. The pooled CGH data from the primary carcinomas revealed a novel region of chromosomal loss on 4q which is also frequently affected in other tumour entities like oesophageal adenocarcinomas and is supposed to harbour a new tumour suppressor gene. Gains on chromosome 9q and of chromosome 16 and loss on chromosome 13q were observed as common aberrations in metastases and primary tumours. These CGH results indicate an accumulation of chromosomal imbalances during the PIN-carcinoma-metastasis sequence and an early origin of tumour-specific aberrations in PIN areas.

Adenocarcinoma↗

PubMed2001

Collaborative exercise on the use of FISH chromosome painting for retrospective biodosimetry of Mayak nuclear-industrial personnel.

PURPOSE: To investigate within the framework of a multilaboratory study the suitability of FISH chromosome painting to measure so-called stable translocations in peripheral lymphocytes of Mayak nuclear-industrial workers (from the Southern Urals) and their use for retrospective biodosimetry. MATERIALS AND METHODS: Chromosime analyses were carried out from 69 workers who had received protracted occupational radiation exposures (0.012-6.065 Gy) up to approximately 40 years before blood sampling. Twenty-one unexposed people living in the same area were controls. A multicolour FISH-painting protocol with the target chromosomes 1, 4 and 8 simultaneously with a pancentromeric probe was used to score potentially transmissible chromosome-type aberrations (reciprocal translocations 2B and related 'one-way' patterns I-III according to the S&S classification). RESULTS: Individual biodosimetry estimates were obtained in terms of these potentially long-term surviving aberration types based on the linear component of a low dose-rate gamma-ray calibration curve produced using identical staining and scoring protocols. For comparison, the workers personal and total background doses were converted to red bone marrow doses. The estimated doses were mainly lower than would be predicted by the calibration curve, particularly at accumulated higher dose levels. CONCLUSIONS: Owing to the limited life-time of circulating T-lymphocytes, the long-term persistence of translocations in vivo requires the assumption of a clonal repopulation of these naturally senescing cells from the haemopoietic stem cell compartments. Obviously such a replacement cannot be fully achieved, leading to a temporal decline even of the yield of transmissible aberrations types. Assuming further a highly selective capacity of stem cells against any type of chromosomal damage and the fact that one must rely on partial genome findings, the potential of FISH chromosome painting for retrospective dose reconstruction is probably limited to a decade or so after high-level protracted radiation exposure.

Adult↗

PubMed2001

Time-course of translocation and dicentric frequencies in a radiation accident case.

PURPOSE: To assess the persistence of exchange aberrations measured by FISH chromosome painting after accidental radiation exposure. MATERIALS AND METHODS: Chromosome analyses were carried out in peripheral lymphocytes of a 13-year-old boy exposed to protracted low dose-rate whole-body and short-time partial-body irradiation from a radiation accident in Estonia in 1994. Up to November 1998, the frequencies of translocations and dicentrics were periodically measured using FISH chromosome painting of the target chromosomes 1, 4 and 12, with a simultaneous pancentromeric probe. RESULTS: For the yields of dicentrics, an expected rapid temporal decline was found with a half-time of 14.2+/-1.9 months. The yields of reciprocal translocations also revealed a gradual but significant reduction with a half-time of 51.7+/-12.7 months. CONCLUSION: An unchanged temporal persistence of so-called stable translocations cannot be assumed. Any significant reduction of this aberration type with time obviously limits the application of FISH-based translocation measurements for reliable long-term biodosimetry after combined protracted whole-body and partial-body radiation exposure.

Adolescent↗

PubMed2001

Instability of microsatellites in radiation-associated thyroid tumours with short latency periods.

PURPOSE: To determine the instability of microsatellite sequences in post-Chernobyl thyroid tumours from children and young adults, and to ascertain whether they correlated with the age of the patient at the time of the accident and the tumour latency period. MATERIALS AND METHODS: The stability of 26 microsatellite markers was investigated in 122 radiation-associated thyroid tumours (96 children, 26 adults) from Belarus and 39 spontaneous thyroid tumours (adults) from Munich without radiation history. RESULTS: A significant correlation between patient age at the time of the accident and the instability of microsatellite sequences was established. Also, a high instability of microsatellite sequences was found in 28 early thyroid tumours from Belarus with latency periods of 6-8 years, in contrast to a low instability of microsatellites in 94 tumours emerging 9-11 years after the accident. Microsatellite instability in the reference group from Munich proved similar to the early thyroid tumours from Belarus. CONCLUSION: Early, fast-growing and aggressive post-Chernobyl thyroid tumours are characterized by an increase in microsatellite instability.

Adolescent↗

PubMed2001

A cluster of childhood leukaemias near two neighbouring nuclear installations in Northern Germany: prevalence of chromosomal aberrations in peripheral blood lymphocytes.

PURPOSE: Between 1990 and 1991 a leukaemia cluster was observed in children living close to the combined site of a nuclear power plant and a nuclear research facility in Elbmarsch, a region in Lower Saxony (Germany). We aim to investigate the prevalence of presumably radiation-induced chromosomal aberrations in peripheral blood lymphocytes of children in Elbmarsch and children of a control region in order to find out whether there was an uncontrolled release of radioactive material which resulted in a substantial exposure. MATERIALS AND METHODS: The frequency of dicentric and ring chromosomes in lymphocytes of the peripheral blood in 42 children in Elbmarsch and 30 children in Plön was investigated. Children in both groups had been permanent residents of the study area. RESULTS: The mean frequency of dicentric and ring chromosomes in Elbmarsch was 14/32580 cells (=0.430 x 10(-3); 95% CI 0.24-0.70 x 10(-3) cells), and in Plön it was 17/24065 cells (=0.706 x 10(-3); 95% CI 0.42-1.10 x 10(-3) cells). CONCLUSIONS: No difference in the frequency of dicentric and ring chromosomes was observed between children in Elbmarsch living close to a combined site of a nuclear power plant and a nuclear research facility and children living in the control area Plön. The power of the study to detect a threefold or higher increase in the aberration frequency was at least 0.86.

Adolescent↗

PubMed2001

Neoplastic transformation and cytogenetic changes after Gamma irradiation of human epithelial cells expressing telomerase.

Neoplastic transformation of human epithelial cells by radiation has previously been investigated using cell lines immortalized with viral vectors. There are disadvantages to this approach, and we report here the results of studies using a human retinal pigment epithelial cell line (340RPE-T53) immortalized by treatment with telomerase. After exposure of the cells to fractionated doses of gamma radiation, there was a marked increase in anchorage-independent growth of the surviving cells. The cloned cell lines derived from these anchorage-independent cultures exhibited an increased growth rate in vitro and were serum-independent compared with the parent cell line. The parent cell line maintained a stable diploid karyotype. The cell lines cloned after irradiation with the lower doses (10 x 2 Gy) were hypodiploid with loss of chromosome 13 and a high level amplification of 10p11.2 associated with a deletion of the remaining short arm segment of chromosome 10 distal to 10p11.2. In contrast, the cell lines cloned after irradiation with the higher doses (15 x 2 Gy) were near-tetraploid with derivative chromosomes present characterized by SKY analysis. Thus this human epithelial cell line immortalized with telomerase provides an improved model to investigate mechanisms of radiation carcinogenesis.

Cell Adhesion↗

PubMed2000

Translocation t(10;14)(q11.2:q22.1) fusing the kinetin to the RET gene creates a novel rearranged form (PTC8) of the RET proto-oncogene in radiation-induced childhood papillary thyroid carcinoma.

Evaluation of 20 cases of radiation-induced childhood papillary thyroid carcinoma using fluorescence in situ hybridization demonstrated the presence of clonal translocations affecting the RET locus. Semiquantitative reverse transcription-PCR indicated overexpression of the RET tyrosine kinase (TK) domain in four cases. In two cases, the RET rearrangements PTC6 and PTC7 were identified and assigned to balanced translocations t(7;10)(q32;q11.2) and t(1;10)(p13;q11.2), respectively. In one case with a balanced translocation t(10;14)(q11.2;q22.1), 5' rapid amplification of cDNA ends revealed a novel type of RET oncogenic activation (PTC8), arising from a fusion of the 5' part of the kinectin (KTN1) gene to the TK domain of the RET gene. The presence of coiled-coil domains in the resulting ktn1/ret fusion protein suggests ligand-independent dimerization and thus constitutive activation of the ret TK domain.

Base Sequence↗

PubMed2000

The effectiveness of monoenergetic neutrons at 565 keV in producing dicentric chromosomes in human lymphocytes at low doses.

The induction of dicentric chromosomes in human lymphocytes from one individual irradiated in vitro with monoenergetic neutrons at 565 keV was examined to provide additional data for an improved evaluation of neutrons with respect to radiation risk in radioprotection. The resulting linear dose-response relationship obtained (0.813 +/- 0.052 dicentrics per cell per gray) over the dose range of 0.0213-0.167 Gy is consistent with published results obtained for irradiation with neutrons from different sources and with different spectra at energies lower than 1000 keV. Comparing this value to previously published "average" dose-response curves obtained by different laboratories for (60)Co gamma rays and orthovoltage X rays resulted in maximum RBEs (RBE(m)) of about 37 +/- 8 and 16 +/- 4, respectively. However, when our neutron data were matched to low-LET dose responses that were constructed several years earlier for lymphocytes from the same individual, higher values of RBE(m) resulted: 76.0 +/- 29.5 for (60)Co gamma rays and 54.2 +/- 18.4 for (137)Cs gamma rays; differentially filtered 220 kV X rays produced values of RBE(m) between 20.3 +/- 2.0 or 37.0 +/- 7. 1. The results highlight the dependence of RBE(m) on the choice of low-LET reference radiation and raise the possibility that differential individual response to low-LET radiations may need to be examined more fully in this context.

Adult↗

PubMed1999

Follow-up analysis of translocation and dicentric frequencies, measured by FISH-chromosome painting in breast cancer patients after partial-body radiotherapy with little bone marrow exposure.

Follow-up translocation and dicentric measurements in blood lymphocytes of five breast cancer patients were performed by FISH using painting probes for chromosomes 1, 4, and 12 simultaneously with a pancentromeric DNA probe, during 14 months after fractionated photon therapy affecting only small areas of the bone marrow (about 5%). The analysis of individual time-courses for translocations and dicentrics revealed a significant temporal decline of the yields with comparable half-times, both for these stable and unstable aberration types in two patients. In three patients, the aberration yields remained fairly unchanged during the observation period. Regarding retrospective biodosimetry for cases with partial-body exposures or large dose inhomogeneity, it follows that even FISH chromosome painting is limited in assessing initial doses correctly in terms of stable translocations.

Bone Marrow Cells↗

PubMed1999

Distinct frequency of ret rearrangements in papillary thyroid carcinomas of children and adults from Belarus.

Rearrangements of the ret oncogene were investigated in papillary thyroid carcinomas (PTC) from 51 Belarussian children with a mean age of 3 years at the time of the Chernobyl radiation accident. For comparison, 16 PTC from exposed Belarussian adults and 16 PTC from German patients without radiation history were included in the study. ret rearrangements were detected and specified by RT-PCR and direct sequencing using specific primers for ret/PTC1, 2 and 3. Only ret/PTC1, and no ret/PTC3, was found in the adult patients, with a frequency of 69% for the Belarussian cases, but of only 19% in the German patients. In contrast, 13 ret/PTC3 (25.5%) and 12 ret/PTC1 (23.5%) rearrangements were present in PTC from Belarussian children. Thus, our study reveals about a 1:1 ratio of ret/PTC3 and ret/PTC1, in contrast to earlier studies with lower numbers of cases and exhibiting a high predominance of ret/PTC3 (ratio about 3:1). A ratio (2.5:1) similar to that in earlier investigations (diagnosed 1991-94) was obtained for cases included in our study that were diagnosed in 1993/94. The present data suggest that ret/PTC3 may be typical for radiation-associated childhood PTC with a short latency period, whereas ret/PTC1 may be a marker for later-occurring PTC of radiation-exposed adults and children.

Adenocarcinoma, Follicular↗

PubMed1999

Cytogenetic changes in radiation-induced tumors of the thyroid.

Thyroid carcinoma incidence is increased significantly after ionizing irradiation; however, the possible mechanisms have not yet been identified. To provide clues for an understanding of the radiation-induced transformation of thyroid epithelium, we analyzed the karyotypes of 56 childhood thyroid tumors that appeared in Belarus after the Chernobyl nuclear accident in 1986. We also studied eight secondary thyroid tumors that developed after radiotherapy. Metaphase preparations obtained from primary cultures were analyzed by G-banding. Clonal structural aberrations were found in 13 of 56 Belarussian cases and in 6 of 8 secondary tumors that developed after radiotherapy. Furthermore, we detected multiple chromosomal aberrations as well as complex rearrangements in some of these tumors and performed a detailed analysis of marker chromosomes from a single case using spectral karyotyping and comparative genomic hybridization in a childhood tumor from Belarus with a near-triploid karyotype. Both comparative genomic hybridization and spectral karyotyping analysis revealed structural alterations affecting identical chromosomes 1, 2, 9, and 13, among others. In addition to the known hot spots of alterations in papillary thyroid carcinomas on chromosomes 1q and 10q, a comprehensive breakpoint analysis in the pooled data set revealed novel breakpoints on chromosomes 4q, 5q, 6p, 12q, 13q, and 14q. The chromosomal aberrations in these tumors may provide suitable starting points for the positional cloning of genes involved in radiation-induced tumorigenesis.

Adolescent↗

PubMed1999

Multicolour FISH painting for the analysis of chromosomal aberrations induced by 220 kV X-rays and fission neutrons.

PURPOSE: The quantification of radiation-induced chromosome aberrations identified by multicoloured FISH painting and classified according to different nomenclature systems (PAINT, S&S and a conventional method). MATERIAL AND METHODS: Blood samples were irradiated with five different doses of 220 kV X-rays or fission neutrons respectively. Cell cycle-controlled, multicoloured FISH painting was performed with a cocktail of chromosomes 1, 4, 12 and a pancentromeric probe. RESULTS: Ten aberration parameters or categories were selected according to the three nomenclature systems and dose-response curves were constructed for the observed yields. Fitted coefficients of the linear-quadratic dose-response function show the relative importance of the quadratic term for aberration parameters of the low-LET radiation (X-rays) data set and of the linear term for those of the high-LET radiation (fission neutrons) data set. The relative proportion of complex aberrations observed was larger for the densely ionizing fission neutrons than for sparsely ionizing X-rays. CONCLUSION: Compared with single-colour FISH painting, a multicolour approach provides extended information for a mechanistic and quantitative interpretation of radiation-induced chromosome aberrations. The choice of a nomenclature system and the selection of an appropriate aberration parameter or category depend on these specific aspects. Practical application requires a rapid and reproducible description of the observed painting patterns and should also throw light on the origin of aberrations.

Cells, Cultured↗

PubMed1999

Microsatellite instability and loss of heterozygosity in radiation-associated thyroid carcinomas of Belarussian children and adults.

DNA from 129 paired thyroid tumorous and non-tumorous tissue samples of Belarussian children (102 patients; age at surgery </=18 years) and adults (27 patients; age at surgery 19-35 years), who had been exposed to radioactive fallout from the Chernobyl reactor accident in 1986, was examined for microsatellite instability (MSI) and loss of heterozygosity (LOH). Twenty-eight microsatellite markers were chosen because of their vicinity to DNA repair genes or genes involved in tumorigenesis as well as regions of chromosomal breakpoints in thyroid tumours. In 40 patients (31% of 129) we detected a total of 73 alterations, 80% of which were classified as LOH and only 20% as MSI. Amongst these 40 patients we identified a subgroup of 11, mainly young female patients (8.5% of 129), exhibiting alterations in at least two microsatellite markers. For comparison we examined samples from spontaneous thyroid carcinomas without radiation history from 20 adult patients from Munich (mean age at surgery 56 +/- 13 years). None of the tumour samples investigated showed evidence of alterations in the 28 microsatellite markers tested. Taken together our data indicate an increased instability of microsatellite markers in thyroid cancers from Belarussian patients. At present, it is uncertain whether the increased genome instability observed in Belarussian patients is the result of the exposure to radioactive iodine from the Chernobyl reactor accident or due to the young age of the patients.

Adolescent↗

PubMed1999

Does the limiting F value at very low doses depend systematically on linear energy transfer?

The debate on the validity of the ratios of radiation-induced yields of chromosome aberrations, in particular the F value (dicentrics/ring chromosomes), as a chromosomal fingerprint of radiation quality is still in progress. From a recent analysis of their experimental data, Sasaki et al. (Radiat. Res. 150, 253-258, 1998) noted that despite a considerable variability in the data, the limiting F value at the lowest doses, or the F(0) value, obviously decreased with increasing LET, indicating that the LET could be a factor that determines the F value. We have reassessed here our own 13 cytogenetic data sets that cover a range of dose-averaged LET of 0.5 to 150 keV/microm in terms of this F(0)-value approach, but we could not confirm such a dependence on LET at very low doses. The validity of the F value as a biomarker therefore remains questionable. For a final evaluation, scoring of a far greater number of cells at low doses would be necessary to reduce the large error ranges of F values.

Cells, Cultured↗

PubMed1998

Technical report: automated classification of first and second cycle metaphases.

Based on the technical configuration of the Metafer2 metaphase finder (Metasystems, Altlussheim, Germany), an automated system was developed that is able to discriminate first/M1 or second cycle/M2 metaphases. For an evaluation of the system in fluorescence plus Giemsa stained preparations of human lymphocytes, a learning sample and an independent test sample was used. Between 8 and 14 separated chromosomes per metaphase were sufficient to achieve correct classification rates between 95 and 100%. For practical application the system can be most efficiently used for biodosimetry of human radiation exposure which requires scoring of thousands of metaphases exclusively in M1. An application for selection of M2 for SCE scoring in mutagenicity testing was possible, but does not provide a comparable advantage.

Azure Stains↗

PubMed1998

Retrospective dose reconstruction of human radiation exposure by FISH/chromosome painting.

Measurements of stable chromosomal aberrations by fluorescence in situ hybridisation (FISH)-chromosome painting has the potential to be used for dose reconstruction, years after exposure to ionising radiation. The method is, however, not yet fully standardised and validated. In particular, with respect to the limited lifespan of circulating T-lymphocytes, a level of uncertainty exists on the long-term persistence of stable aberrations. The main principles of the technique will be demonstrated. Based on results from the literature, the reliability and limitations are discussed.

Calibration↗