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M Bauchinger

Publications and source records attributed to M Bauchinger.

At least 73 records · Page 4Linked to original sources
PubMed1994

Dose-response relationships of micronuclei in human lymphocytes induced by fission neutrons and by low LET radiations.

The induction of micronuclei in cytokinesis-blocked human lymphocytes of different donors has been measured after G0 irradiation in vitro with a mixed fission neutron-gamma-ray beam, 220 kV X-rays and 60Co gamma-rays. The dose-response relationships for the micronucleus yields were linear-quadratic for both types of low LET radiations. The linear model applied for neutron-induced micronuclei over the dose range 0-0.66 Gy. At higher doses a saturation effect became apparent. For neutron-induced micronucleus yields a limiting RBE value of 12.2 was derived from the ratio of the alpha coefficients of neutrons and 60Co gamma-rays.

Cells, Cultured↗
PubMed1994

Chromosome aberrations in nuclear power plant workers: the influence of dose accumulation and lymphocyte life-time.

Chromosome analyses were performed in blood lymphocytes of 22 nuclear power plant workers with a mean accumulated radiation dose of 390 mSv (270-530 mSv). Nineteen workers had received 300 mSv 4-16 years prior to sampling. The frequency of dicentrics and ring chromosomes (1.75 x 10(-3)) was significantly elevated as compared to a control group (0.58 x 10(-3)). Based on the initial slope of an in vitro 60Co gamma-ray curve, a biological dose estimate of only 110 mSv was derived. This can be interpreted in terms of an "equivalent-acute" dose at the time of blood sampling which can be derived by weighting annual doses during working periods of 12-30 years for a mean life-time m of lymphocytes. The annual doses were additionally weighted for a uniform distribution during a whole year. Using m = 10 years, a mean "equivalent-acute" dose of 90 mSv (64-157 mSv) is obtained, which compares more closely to the biologically estimated dose than 20 mSv (7-71 mSv) based on m = 4.3 years.

Adult↗
PubMed1994

Numerical abnormalities of chromosome 7 in human prostate cancer detected by fluorescence in situ hybridization (FISH) on paraffin-embedded tissue sections with centromere-specific DNA probes.

Fluorescence in situ hybridization (FISH) using chromosome-specific alpha-satellite DNA probes for chromosomes 7, 8, and 12 was performed on paraffin-embedded tissue sections and touch imprint preparations of 53 cases of human prostate cancer. Subsequent haematoxylin and eosin (H & E) staining of the hybridized tissue sections allowed unambiguous assignment of hybridization signals either to tumour or to non-tumorous parenchyma. Fifty-three cases of human prostate cancer were evaluated for numerical aberrations of chromosome 7. Scoring 200 cells of tumour and non-tumorous parenchyma in each case revealed abnormalities exclusively in tumour parenchyma in 41 cases (77 per cent). Ten of 41 cases (24 per cent) showed trisomy 7, and 15 cases (37 per cent) monosomy 7 or trisomy 7 in combination with monosomy 7, respectively. Sixteen cases (39 per cent) exhibited polysomy 7 in cells of the tumour parenchyma. In the tumour tissue in one case, different polyploid clones (triploid, tetraploid) and polysomy 7 could be identified by double hybridization with chromosome-specific DNA probes for chromosome 7, plus 8 or 12. The indicated numerical aberrations of chromosome 7 were correlated with 78 per cent of advanced pathological stages or poorly differentiated tumours (pT3/4 or G3) of prostate carcinomas. A statistical analysis of the data revealed significant relationships of particular numerical abnormalities of chromosome 7 to different pathological categories (pT, G, pN) of tumour classification. For the T-classification, the frequency of cells carrying polysomy 7 and polysomy 7/+7 increases significantly from pT1 to pT3/4 (P = 0.022).(ABSTRACT TRUNCATED AT 250 WORDS)

Centromere↗
PubMed1994

Two-phase short-term culture method for cytogenetic investigations from human prostate carcinoma.

An improved technique for primary short-term culture of prostate carcinoma cells in two phases, with and without serum, for subsequent cytogenetic analysis is reported and compared with four other methods. After mechanical disaggregation and a brief collagenase treatment of tumor specimens, cell clusters were seeded in RPMI 1640 and 15% fetal calf serum (FCS) without any other supplement in the first phase. The culture medium was changed to a serum-free medium supplemented with bovine pituitary extract (BPE) and epidermal growth factor (EGF) when the first outgrowth became apparent. During this second phase, fibroblast growth could be virtually abolished within 48 hr. The epithelial and prostatic origin of the cultured cells was confirmed by immunocytochemical methods in each culture. Metaphase analysis revealed chromosome aberrations in over 80% of cases (both clonal and nonclonal alterations) indicating the presence of neoplastic cells. Clonal numerical chromosome aberrations, found by conventional cytogenetic analysis, were used to provide the reliability of the culture system in interphase nuclei of corresponding uncultured tumor tissue by fluorescence in situ hybridization (FISH). The main points of the described method are: 1) combined mechanical/enzymatic disaggregation, 2) seeding of the disaggregated cell clumps rather than of single cells, 3) initialization of the cultures in RPMI 1640 medium with 18% FCS without any other supplements, and (4) stimulating of selective epithelial proliferation by changing the culture conditions through serum-free medium.

Antigens, Neoplasm↗
PubMed1994

Analysis for DNA-proportional distribution of radiation-induced chromosome aberrations in various triple combinations of human chromosomes using fluorescence in situ hybridization.

Fluorescence in situ hybridization (FISH) with five cocktails of composite whole chromosome-specific DNA probes 1, 4, 12; 2, 7, 9; 2, 7, 9dig; 3, 6, 10dig and 8, 14 Xdig and a degenerate alpha-satellite pancentromeric DNA probe was used to examine in vitro radiation-induced symmetrical translocations and dicentrics in peripheral lymphocytes for a DNA-proportional distribution. For a discrimination between morphologically similar target chromosomes, chromosomes 9, 10 and X were labelled with digoxigenin (dig). Among the five combinations, significantly higher translocation frequencies than expected from the DNA content were found in 8, 14, Xdig, whereas for this combination no deviation became apparent for dicentrics. The chromosome-specific analysis showed that chromosome 2 was involved in fewer symmetrical translocations, whereas chromosomes 9, 10 and 12 were more frequently involved in dicentrics than predicted. Comparing the ratios of symmetrical translocations to dicentrics, an excess of symmetrical translocations was found for the combinations 1, 4, 12; 2, 7, 9dig and 8, 14, Xdig and for the chromosomes 1, 4, 6, 7, 8 and X. Provided the present data can be confirmed in further experiments, the formula Y = 2.05fi(1--fi)FG, relating the translocation or dicentric frequency measured by FISH to the respective genomic FG (fi is the labelled genomic fraction) cannot be used to scale up to equal the full genome unless appropriate weighting factors are included.

Adult↗
PubMed1993

Cytogenetic effects of promutagens in genetically engineered V79 Chinese hamster cells expressing cytochromes P450.

V79 Chinese hamster cell lines genetically engineered to express rat CYP2B1, CYP1A1, CYP1A2, and their parental cell lines V79-MZ, without acetyltransferase, and V79-NH, with acetyltransferase, were studied for chromosome aberrations and sister chromatid exchange induced by aflatoxin B1, cyclophosphamide, benzo[a]pyrene, 7,12-dimethylbenz[a]anthracene and dimethylnitrosamine. The parental V79 cell lines did not show clastogenic effects. Significant clastogenic effects were observed after an 18 h exposure to aflatoxin B1 and cyclophosphamide in CYP2B1 expressing cells, to benzo[a]pyrene in CYP1A1 and CYP1A2 expressing cells, to 7,12-dimethylbenz[a]anthracene and dimethylnitrosamine in cells, expressing CYP1A2 with or without acetyltransferase, and to cyclophosphamide in cells expressing both CYP1A2 and acetyltransferase. A significant sister chromatid exchange inducing effect was found after a 24 h exposure in each of the genetically engineered cell lines, except for benzo[a]pyrene and 7,12-dimethylbenz[a]anthracene in CYP2B1 expressing cells, and for benzo[a]pyrene in cells expressing both CYP1A2 and acetyltransferase. Thus, a battery of cell lines genetically engineered for metabolic competence may serve as a tool for investigating chromosomal changes induced by activated xenobiotics.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1993

Radiation-induced chromosome aberrations analysed by two-colour fluorescence in situ hybridization with composite whole chromosome-specific DNA probes and a pancentromeric DNA probe.

Fluorescence in situ hybridization with composite whole chromosome-specific DNA probes for human chromosomes 1, 4 and 12 and a degenerate alpha-satellite pancentromeric DNA probe labelled with digoxigenin was used to measure symmetrical translocations and dicentrics induced in vitro by 137Cs gamma-rays (0-6.0 Gy) in peripheral lymphocytes. Despite subtracting our mean background translocation frequency of 0.0016 per cell (11,411 cells scored from 11 individuals) from induced frequencies, about 1.3-1.8-fold more translocations were found than dicentrics at a given dose. Translocation frequencies determined only in stable cells agree well with total translocation frequencies determined also in cells containing additional unstable chromosomal changes. The linear quadratic calibration curve generated for total stable translocations is based on approx. 17,000 cells. The suitability of this curve for biological dosimetry of human radiation exposure can now be evaluated in comparison with dose estimates based on a conventional dicentric dose-response curve.

Cesium Radioisotopes↗
PubMed1993

Development of short-term mutagenicity test systems in vitro: metabolic activation of indirectly acting mutagens by three immortal rat hepatocyte lines.

The metabolic capacity to activate the indirectly acting promutagens aflatoxin B1, cyclophosphamide, benzo[a]-pyrene, 7,12-dimethylbenz[a]anthracene and dimethylnitrosamine into DNA-reactive metabolites was investigated in three immortalized rat hepatocyte cell lines (NRL cl-B, NRL cl-C and ARL) by analysing chromosome aberrations and sister chromatid exchange (SCE). In all three cell lines a significant clastogenic and SCE inducing response was observed after exposure to each test compound. Furthermore, activities of the two enzymes aryl hydrocarbon hydroxylase and aldrin-epoxidase, which play major roles in the cytochrome P450-dependent metabolism, could be determined in all cell lines. In contrast to the hepatocyte lines in V79 Chinese hamster cells, which were used as a reference cell line without any cytochrome P450 metabolizing capacity, no arylhydrocarbon hydroxylase or aldrinepoxidase activities were detected. A cytogenetic response to the test compounds was only observed in the presence of the exogenous activating system S9 mix. Due to the wide, efficient and stable spectrum of their metabolizing capacities, the tested rat hepatocyte lines offer promising perspectives as alternative assay systems for the detection of indirectly acting mutagens.

Animals↗
PubMed1993

[Cytogenetic investigations in primary prostate carcinomas].

Primary cultures of 48 cases of prostate carcinoma were established. The expression of cytokeratin and prostate specific antigen were determined in the cultures routinely. G-banding analysis revealed some clonal numerical and structural aberrations: Trisomy 7 occurred in 4 cases, in one case in combination with a t(Y;22). Loss of the Y chromosome was found in 3 cases, in one case in combination with gain of chromosome #5. The most frequent clonal structural aberration var9(qh) occurred in 6 cases. A deletion of 6q(23) was found in two cases. None of these aberrations were found in normal tissue of the same patients. Numerical changes were demonstrated by fluorescence in situ hybridization (FISH) on native tissue, confirming the conventional cytogenetic findings.

Chromosome Aberrations↗
PubMed1992

Multiparametric flow cytometric analysis of radiation-induced micronuclei in mammalian cell cultures.

A new flow cytometric method is presented that quantifies the frequency of radiation-induced micronuclei in mammalian cell cultures with high precision. After preparing a suspension of main nuclei and micronuclei stained with ethidium bromide and Hoechst 33258, both types of particles are measured simultaneously in a flow cytometer using forward light scatter and three fluorescence emission intensities excited by UV, 488 nm, and by energy transfer from Hoechst 33258 to ethidium bromide. Nonspecific debris overlapping the micronucleus distribution especially in the low fluorescence intensity region was discriminated from micronuclei by calculating ratios of the different fluorescences. The frequencies of radiation-induced micronuclei measured with this new technique agreed well with results obtained by conventional microscopy. The lower limit of the DNA content of micronuclei identified by this technique was found to be about 0.5%-0.75% of the DNA content of G1-phase nuclei. Dose effect curves and the time-dependent induction of micronuclei were measured for two different mouse cell lines.

Animals↗
PubMed1992

Centromere detection in vinblastine- and radiation-induced micronuclei of cytokinesis-blocked mouse cells by using in situ hybridization with a mouse gamma (major) satellite DNA probe.

Non-isotopic in situ hybridization using a mouse gamma (major) satellite probe DNA was applied to detect centromeres in micronuclei, which were induced in vitro in mouse liver cells by ionizing radiation and by vinblastine sulfate. In a cytokinesis-blocked micronucleus assay a dose-dependent induction of micronuclei was found for both agents. After vinblastine exposure the observed micronuclei showed centromere-positive hybridization signals in an order of magnitude of 70-90%, but after radiation exposure the magnitude was only 10-20%. Since the in situ hybridization technique detects centromeric DNA directly, it can be used in a cytokinesis-blocked micronucleus assay for a rapid and reliable discrimination between aneuploidy-inducing and clastogenic agents.

Animals↗
PubMed1992

Chromosome analysis in a population living in an area of Germany with the highest fallout deposition from the Chernobyl accident.

Chromosome analyses were carried out in 1989 in peripheral lymphocytes of 30 persons from the region in southeast Bavaria (Berchtesgaden) that received the highest radiocesium deposition (> 42 kBq/m2) in Germany. These persons belonged to a group for whom body burdens of radiocesium had been surveyed in 1987. Chromosome analyses had been performed by Stephan and Oestreicher for members of the same group in the period 1987-1990, and these authors have reported elevated rates of chromosome aberrations. Pohl-Rüling et al. (1991) have, likewise, concluded that there have been increased rates of chromosome aberrations in the population of the nearby Salzburg region in 1987. In the study reported here we do not see any elevations compared to our large pre-Chernobyl control group. The difference between our findings and the report of earlier increases cannot be fully explained in terms of the known temporal decrease of the rate of dicentrics and ring chromosomes.

Accidents↗
PubMed1992

Clastogenicity of 2-chlorobenzylidene malonitrile (CS) in V79 Chinese hamster cells.

The clastogenicity of the sensory irritant 2-chlorobenzylidene malonitrile (CS) to V79 Chinese hamster cells was investigated at various exposure conditions. CS efficiently induced chromatid-type aberrations in a dose-dependent manner provided the cells could run through at least one or two S-phases during a 20-h exposure over a 3-h exposure followed by a 20-h recovery period (cell cycle time 8-10 h). The induction of SCEs indicates an S-dependent mechanism. The hydrolysis products o-chlorobenzaldehyde and malonitrile were inactive in these experiments.

Animals↗
PubMed1992

Intra- and inter-individual variation of background and radiation-induced micronucleus frequencies in human lymphocytes.

Serial blood samples were taken from four healthy individuals (three males, one female, aged between 26 and 51 years) in 3-monthly intervals during 1 year. Leucocyte suspensions were prepared and exposed to 3 Gy of 137Cs gamma-rays or left unirradiated as controls. In a cytokinesis-blocked (CB) micronucleus (MN) assay significant inter- and intra-donor variations of background and radiation-induced MN incidences became apparent. The two sources of variation lead to an extra variance sigma I2, in addition to the sample variance sigma e2 of MN incidences. The contributions of the different components to the total variance were estimated by means of a variance component model. The deviation sigma I for the mean background MN level of 1.53 x 10(-2) MN/CB cell was +/- 0.67 x 10(-2) and for the mean radiation-induced MN level of 0.53 MN/CB cell it was +/- 0.10. The contribution of the intra-individual variance to sigma I2 was about 50% for background MN levels and 75% for radiation-induced MN frequencies. With respect to the application of the CB-MN assay as a biological dosimetry system, the consequences of the present findings for calibration purposes and low-dose estimation are discussed. The calculation of the variance components is explained in an appendix, which serves also as an example for the adaptation of analysis of variance techniques to the evaluation of data derived from scoring of MN, as well as from scoring of metaphase chromosomal aberrations.

Adult↗
PubMed1992

Radiation-induced chromosome aberrations analysed by fluorescence in situ hybridization with a triple combination of composite whole chromosome-specific DNA probes.

Fluorescence in situ hybridization (FISH) with a combination of three composite whole chromosome-specific DNA probes for human chromosomes 1, 4 and 12 was used to analyse in vitro radiation-induced dicentrics and symmetrical translocations in peripheral lymphocytes. Translocations could be rapidly and efficiently detected by FISH. Their frequencies were 1.8-fold higher than the frequencies for dicentrics at a given dose. The dose-response curves for translocations and dicentrics were linear quadratic with a significant higher quadratic component for translocations. The application of FISH for scoring stable translocations for biological dosimetry of radiation exposures is discussed.

Adult↗
PubMed1992

An automated flow cytometric micronucleus assay for human lymphocytes.

A new flow cytometric method is presented for scoring micronuclei (MN) in human lymphocytes after in vitro gamma-irradiation. Fifty to fifty-five hours after PHA-stimulation, the frequency of micronuclei per nucleus and the fraction of cells in the second cell cycle were measured using flow cytometry. All data were automatically analysed using our DAS-software package. Eight individual linear-quadratic dose response curves derived from five donors revealed inter- and intra-individual variabilities of all curve parameters. Since also an age dependence was found for spontaneous MN-frequencies and for the linear curve parameter, a combined linear-quadratic age-dose-effect model was used to fit the data. The 90% prediction intervals show that a reliable individual dose estimation for donors aged between 23 and 54 years cannot be achieved for exposures below 1 Gy.

Adult↗
PubMed1991

Chromosome analyses in chronic lymphocytic leukemia and related B-cell neoplasms.

Chromosome analyses were performed by routine G-banding in 29 patients with B-cell chronic lymphocytic leukemia (B-CLL), six with immunocytoma (IC), three with centroblastic-centrocytic (cb-cc) lymphoma, and one with hairy cell leukemia (HCL). Ages of the patients were between 46 and 81 years (mean, 63 years). 12-O-tetradecanoyl-phorbol-13-acetate (TPA) was used as a mitogen to stimulate leukemic B-cells in 72-hour cultures. Twenty-one patients had one or more chromosomal abnormalities; and in 13 patients, they were clonal; 18 patients had a normal karyotype. Seven patients had trisomy 12 (three B-CLL, two IC, two cb-cc lymphoma); two (B-CLL) had it as the sole abnormality. One patient with B-CLL had trisomy 18 as the sole abnormality, and one with IC had trisomy 18 in combination with trisomy 19. One patient with B-CLL had t(1;6)(p36;p21) as a clonal structural abnormality. A t(11;14)(q13;q32) was consistently observed in one patient with cb-cc lymphoma together with inv(1) (p22p36), der(4)t(4;?)(p16;?), del(6)(q13) and other variable changes. One patient with morphologically atypical B-CLL had t(1;11)(p36;q13) together with der(X)t(X;?)(q26;?), der(3)t(3;?)(q29;?), der(8)t(4;8)(q12;q24.1) and additional variable changes. Both patients with these complex karyotypes were in an advanced stage of disease (Binet stage C) and died within 3-6 months after chromosome analysis.

Aged↗