bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluation of an exposure system using cells grown on collagen gels for detecting highly volatile mutagens in the CHO/HGPRT mutation assay
Authors: Zamora P. O. , Benson J. M. , Li A. P. , Brooks A. L. 
Published: February 2007

AbstractChinese hamster ovary (CHO) cells were grown on hydrated collagen gels, the overlaying medium removed leaving the cells at an air/collagen interface, and the cells exposed to a dynamic flow of ethylene oxide. Increases in CHO cell mutant frequency and decreases in cell viability were observed. To establish if the exposure system could be simplified, cells were exposed in sealed bottles (static system) to ethylene oxide. No substantial changes in cytotoxicity, mutant frequency, or effective concentration were noted when comparing static versus dynamic exposure systems. The general usefulness of the exposure system using cells grown on collagen gels was evaluated in a static system using propylene oxide and 1,2‐dichloroethane, both of which were found to be mutagenic and cytotoxic. Comparatively, the exposure of cells by the collagen gel method was as effective in detecting genotoxic damage as were conventional methods (cells covered with medium) using cells grown on glass substrates. The exposure of CHO cells on collagen gels to highly volatile mutagens was simple and inexpensive, and may be generally useful in the detection of gaseous or volatile mutagens.
The induction of bacterial mutation and hepatocyte unscheduled DNA synthesis by monosubstituted anilines
Authors: Thompson Christina Z. , Hill Leo E. , Epp Janet K. , Probst Gregory S. 
Published: February 2007

AbstractA group of 45 monosubstituted aniline compounds was tested for the induction of point mutations in Salmonella typhimurium and Escherichia coli as well as for unscheduled DNA synthesis (UDS) in rat hepatocyte culture. Eleven compounds were bacterial mutagens, and five compounds induced UDS. Among these a correspondence between mutagenicity and UDS occurred for only two compounds (o‐phenylenediamine and 4‐aminobiphenyl), and these were also reported to be carcinogenic in rodents. Bacterial mutation was observed for one compound (p‐phenylenediamine) not carcinogenic in rodents, and six suspect carcinogens were not detected in either test. In addition, eight compounds of unknown carcinogenic potential induced either bacterial mutation or UDS.
Sister chromatid exchange distributions in rabbit lymphocytes treated with streptonigrin
Authors: DuFrain Russell J. 
Published: February 2007

AbstractStreptonigrin (NSC‐45383), a direct‐acting clastogen which induces SCEs in vivo and chromosome aberrations both in vivo and in vitro, was evaluated for SCE induction in both G0 and stimulated rabbit lymphocytes. Determinations were made for 16 cultures from seven female rabbits. These included controls as well as cells exposed to 90 μg/kg in vivo, cells pulse‐treated with 50 ng/ml in vitro, and a culture continuously exposed to 5 ng/ml in vitro. For all cultures the SCE/ cell frequency was determined from 20 complete (44 chromosome) metaphases and, in selected cultures, SCEs on individual chromosomes (880 per culture from 20 cells) were enumerated to determine SCE/chromosome frequency and the chromosomal distribution of SCEs. Analysis of variance and least significant difference tests of the √x transformed SCE/cell data show that cells exposed to Streptonigrin while dividing have significantly higher (P<0.01) frequencies (over double the control 5.3 SCE/cell value) whereas treated G0 cells were not significantly different from the controls. Dispersion analysis of both SCE/cell and SCE/ chromosome data confirms the adequacy of the Poisson distribution for spontaneous or baseline but not streptonigrin‐induced SCEs.
Further study on the cytogenetic effects of combined chemotherapy with isoniazid and para‐aminosalicylic acid on human lymphocytes in vivo: Sister chromatid exchanges, chromosome aberrations in first‐division metaphases, cell growth kinetics, and mitotic index
Authors: Jaju Madhuri , Jaju Manjula , Ahuja Y. R. 
Published: February 2007

AbstractTuberculosis patients under therapy with the drug combination isoniazid (INH) and para‐aminosalicylic acid (PAS) were screened to investigate the cytogenetic effects. Results were compared with those from the patient controls (ie, tuberculosis patients before starting drug therapy) and general controls (individuals from the general population). The induction of chromosome aberrations was homogeneous and increased significantly in all the drug‐exposed patients, whereas the frequency of sister chromatid exchanges (SCEs) was increased only in one of them. These results indicated differences in the two processes: chromosome aberrations and SCEs. Patients under therapy exhibited no change in cell growth kinetics, but the mitotic index was slightly enhanced compared to patient controls. It is concluded that the drug combination of INH+PAS induces damage in lymphocyte chromosomes in vivo. Further studies should be carried out on germ cells.
Evaluation of the genotoxic and embryotoxic potential of chlorpyrifos and its metabolites in vivo and in vitro
Authors: Muscarella Donna E. , Keown Jeffrey F. , Bloom Stephen E. 
Published: February 2007

AbstractThe genotoxicity and embryotoxicity of chlorpyrifos (CPF) and two metabolites were evaluated using the chick embryo, Chinese hamster ovary cells, and by examing blastocysts from superovulated cows crossed to chlorpyrifos‐treated bulls. Chlorpyrifos and metabolites were dissolved in acetone and administered to 3‐day embryos by the air cell method. The LD50 was 1,500 μg/embryo when mortality was checked through and including 17 days of development. The metabolites were more embryotoxic than the parent compound, CPF. Chlorpyrifos and metabolites did not increase the sister chromatid exchange (SCE) frequency above background at any dosage in the 3‐day chick embryo assay. Similarly, none of these compounds increased SCE frequencies in three‐point dosage tests (1, 10, 100 μg/ml) using Chinese hamster ovary cells. Controls in these assays consisted of the solvent carrier acetone (7.0 ± 2.5 SCE/cell) and 8.6 μg/ml methyl methane sulfonate (30.5 ± 7.4 SCE/cell). Studies of bovine blastocysts obtained from superovulated cows crossed with Dursban 44 treated bulls did not reveal evidence of chromosome aberrations or developmental anomalies associated with pesticide application. However, reproductive performance of breeders may be subnormal as a result of severe poisoning. This underscores the limitations of short‐term assays and emphasizes the need to perform thorough toxicological assays of a chemical according to actual usage patterns in the species of concern.
Effects of temperature on the frequency of sister chromatid exchanges (SCEs) in peripheral blood lymphocytes of man and muntjac
Authors: Das B. C. , Sharma T. 
Published: February 2007

AbstractThe incidence of sister chromatid exchanges (SCEs) and cell proliferation kinetics have been studied in peripheral blood lymphocytes of man and muntjac grown at 33 to 44 °C to gain insight into SCE formation. The frequency of SCEs increased as a function of growth temperature. At a given temperature, however, the frequency of SCEs varied with the sampling times; the early sampled cells showed fewer SCEs than did those harvested late. At 33 °C the frequency of SCEs was lowest and there was a marked delay in cell‐cycle progression. The number of SCEs was maximum at 40 °C in human and 42 °C in muntjac. Cell proliferation was markedly affected at higher temperature and 44 °C was found to be intolerable for lymphocytes of both the species. It is proposed that certain temperature‐dependent enzyme(s) associated with DNA replication kinetics may be involved in the formation of SCEs.
Induction of persistent hypersensitivity to lung tumorigenesis by in utero X‐radiation in mice
Authors: Nomura Taisei 
Published: February 2007

AbstractA single dose (36 rad) of X rays was given to mouse embryos and neonates that were then treated with urethane at 21 days of age. Although in utero X‐radiation to mice was not tumorigenic, it significantly increased lung tumor susceptibility to a postnataliy‐given carcinogen, urethane. X‐ray induction of persistent hyper‐sensitivity to lung tumorigenesis was apparent at all stages during days 0 to 14 of gestation (except on day 6), but was not observed at late fetal and neonatal stages.
Influence of strong magnetic fields on genetic endpoints in Tradescantia tetrads and stamen hairs
Authors: Baum John W. , Nauman Charles H. 
Published: February 2007

AbstractInflorescences from Tradescantia clones 4430 and 02 were subjected to mean magnetic field intensiteis of 0.16 or 0.76 to 0.78 tesla for 6 to 11 days. Following exposures to both intensities, damage to pollen mother cell chromosomes at early prophase was determined by scoring the frequency of micronuclei in early tetrads. Pink mutations in stamen hair cells of clone 4430 were scored for 15 days after a 6‐day exposure to the higher intensity level while clone 02 was scored during and for 6 days after an 11‐day exposure to the 0.16 tesla field. Comparison of micronuclei results from exposed groups to those for control groups that were scored concurrently showed that there was no significant difference in frequency for either clone or either field intensity (P values in contingency table analyses were between 0.42 and 0.6); similarly, pink mutation frequencies for clone 4430 exposed and control groups did not differ significantly (a contingency test yielded χ2 = 1.4 and P = 0.26). Comparisons of pink mutation frequencies during the first 6 days of clone 02 exposure to those in the period when an effect should be greatest (days 7 through 17 revealed no significant difference (χ2 = 2.6 and P = 0.1) between the two scoring periods, through frequencies were higher during the early scoring period.
Mutagenicity in a modified Salmonella assay of fabric‐protecting products containing 1,1,1‐trichloroethane
Authors: Nestmann Earle R. , Otson Rein , Kowbel David J. , Bothwell Peter D. , Harrington Tina R. 
Published: February 2007

AbstractMethyl chloroform (1,1,1‐trichloroethane) was identified as a major component in two fabric‐protector spray products. Mutagenic effects were determined at several dosage levels for the two products and some of the identified components. Levels of organics in the air of sealed desiccators, used as exposure chambers in modified Salmonella reversion assays, were measured by a gas chromatographic technique. Both fabric protectors and two samples of trichloroethane were mutagenic in strain TA 1535 and one of each was mutagenic in strain TA 100. Other constituents, such as petroleum distillate and p‐dioxane, were nonmutagenic at the tested exposure levels.
Stem‐Spermatogonial Survival and Incidence of Reciprocal Translocations in the γ‐Irradiated Boar
Authors: Erickson B. H. , Martin P. G. 
Published: February 2007

AbstractTo assess the effects of γ‐radiation on stem‐cell survival and incidence of reciprocal translocations, boar testes were irradiated with 100, 200, or 400 rad. Stem‐cell survival was markedly affected by 100 rad (51 % of control) and reduced to 34% of control by 400 rad. Production of differentiating spermatogonia was all but completely interrupted by 200 rad and spermatogonial renewal was incomplete at 12 weeks. From the state of the seminiferous epithelium at 12 weeks, estimates of the percentage of permanent impairment of sperm‐producing capacity ranged from 20 ± 6 (100 rad) to 67 ± 10 (400 rad). Incidence of translocations peaked at 200 rad and the number occurring at 100 and 400 rad was similar. Kinetics of porcine spermatogonial renewal differs considerably from those of the rodent and, relative to the rodent, this may account for the boar's higher sensitivity to stem‐cell killing and lower sensitivity to translocations.
An assay to detect chemically induced DNA repair in rat spermatocytes
Authors: Working Peter K. , Butterworth Byron E. 
Published: February 2007

AbstractAn in vivo/in vitro DNA repair assay has been developed to quantitate chemically induced unscheduled DNA synthesis (UDS) in rat spermatocytes utilizing autoradiography. Male Fischer‐344 rats were treated by i.p. injection or gavage with a variety of genotoxic agents dissolved in dimethyl sulfoxide, corn oil, or water. At selected times after treatment, spermatocytes were isolated by trypsin digestion of testes and cultured for 24 hr in the presence of 3H‐thymidine. The direct‐acting genotoxicants methyl methanesulfonate (MMS) and ethyl methanesulfonate and the chemotherapeutic agent cyclophosphamide (CPA) produced positive UDS responses in spermatocytes isolated 1 hr after i.p. injection. The UDS response evoked by either CPA or MMS was maximal within 1 hr after injection and declined rapidly thereafter to control levels. Other known genotoxicants—including dimethylnitrosamine, aflatoxin B1, 2‐acetylaminofluorene, 2,6‐dinitrotoluene, and 1,6‐dinitropyrene—failed to induce UDS, even with routes of administration and at times of exposure known to produce a positive response in hepatocytes. This negative response is consistent with these genotoxicants lack of mutagenic effect in rodent germ cells. These results demonstrate that the in vivo/in vitro spermatocyte DNA repair assay may be useful as a predictive screen for germ cell mutagens. Moreover, by its compatibility with similar assays which utilize other tissues from the same treated animal, this assay permits assessment of the organ specificity of the genotoxic response.
Anaphase‐telophase analysis of chromosomal damage induced by chemicals
Authors: Dulout Fernando N. , Olivero Ofelia A. 
Published: February 2007

AbstractThree main aspects involved in the chemical induction of anaphase‐telophase aberrations in the first mitosis after treatment were analyzed: 1) the relationship between the frequency of anaphase‐telophase aberrations and the time of fixation after treatment; 2) the dose‐response relationships; and 3) the proliferative rate of cells exposed to chemicals which interact with DNA by different mechanisms. Experiments were carried out using Chinese hamster ovary (CHO) cells. The compounds examined were adriamycin (ADR) and mitomycin C (MMC). The frequency of cells with chromatin bridges or with lagging chromosomes as well as the mitotic index was determined in each experiment. The results obtained showed that 1) chromatin bridges and lagging chromosomes are apparently induced during the S period of the previous interphase; 2) the increase in the cytotoxicity index (inferred from the mitotic index) and the frequency of cells with chromatin bridges and lagging chromosomes were proportional to the treatment lapse and to the dose employed; and 3) the effect of ADR on cell growth differs from the effect of MMC. While ADR decreased the mitotic activity of cells in logarithmic growth phase, MMC induced mitotic delay. In accordance with these results, the occurrence of chromatin bridges in anaphase‐telophase could be explained by the induction of chromosome stickiness and, to a lesser extent, by the induction of exchange‐type aberrations. On the other hand, lagging chromosomes seem to be the result of chromatid or chromosome breaks because the lagging chromosomes observed were primarily, if not all, fragments and not whole chromosomes. Our evaluation of the anaphase‐telophase test indicates that it is very sensitive method for the detection of chemical clastogens, but other factors, such as mitotic depression, must be taken into account to avoid false‐negative results.
Chromium (VI) Potentiates Mutagenesis by Sodium Azide But Not Ethyl Methanesulfonate
Authors: Lavelle James M. , Witmer Charlotte M. 
Published: February 2007

AbstractA fluctuation test using Salmonella typhimurium strain 1535 has been used in an experimental protocol to assess biological effects of interactions between chromium (VI), such as K2CrO4, and two DNA‐damaging agents, ethyl methanesulfonate (EMS), and sodium azide. Mutagenicity, expressed as the average number of mutations induced over a parallel control, was determined for the compounds alone and in combination. The significance of the differences between the “expected” response, calculated by simple addition of the responses from the individual tests, and the observed response when the combination was tested, were estimated by chi square. For the combination of K2CrO4 and NaN3, the response was significantly greater than expected suggesting a possible potentiation of mutagenesis. The opposite (a less‐than‐additive response) was found for the K2CrO4/EMS combination. Both effects were found to be dose related to the concentration of potassium chromate used. Toxicity of the compounds or their combinations to the bacteria could not explain the results.
Assessing the effect of colony counting methods and genetic drift on ames bioassay results
Authors: Claxton Larry D. , Toney Stephanie , Perry Erica , King Leon 
Published: February 2007

AbstractAccuracy of automatic colony counters and variation among subcultures of the Salmonella tester strains are two factors that cause variation within the Ames bioassay. This paper examines these potential sources of variation. In contrast to results seen by other researchers, this genetic drift study demonstrated that except for TA100 the subcultures of tester strains from four research laboratories are very stable in biochemical characteristics measured using Analytical Profile Index (API) strips. This study also documented the levels of accuracy for hand‐ and automatic‐counting techniques, and provides a simple method for generating acetate calibration transparencies for use with most colony counters.
Assessment of mutagenic damage by monofunctional alkylating agents and gamma radiation in haploid and diploid frogs, Xenopus iaevis
Authors: Hart Donald R. , Armstrong John B. 
Published: February 2007

AbstractAdult male South African clawed frogs, Xenopus laevis, were mutagenized by 3‐day immersion in aqueous solutions of ethyl methanesulfonate (EMS), diethyl nitrosamine (DEN), or ethyl nitrosourea (ENU), or by acute exposure to gamma radiation. They were then spawned repeatedly at 2‐week intervals with untreated females, and embryonic survival of the progeny was used to assess genetic damage. Recessive lethal effects were assessed from reduced survival of androgenetic haploid progeny. Neither recessive nor dominant lethal effects were obtained after exposure to 100 mg/liter EMS or 2 g/liter DEN. At 250 mg/liter EMS, peak dominant lethality occurred 3–5 wk after treatment. Most embryos hatched, but many were abnormal and died shortly after hatching. Haploid survival was significantly reduced over a broader period, from 1 to 13 wk after mutagenesis. Treatment with 75 mg/liter ENU produced effects similar to the 250‐mg/liter EMS mutagenesis. At 400 mg/liter EMS, the frequency and severity of the effects on both diploid and haploid embryos were increased over the lower dose. Gamma irradiation at 1,500 R produced effects similar to the 400‐mg/liter mutagenesis, except that peak dominant lethality extended from 1 to 7 wk.
Mutagenicity of lichen constituents
Authors: Shibamoto T. , Wei C.‐L. 
Published: February 2007

AbstractUsnic acid (the most abundant lichen constituents), physodic, and physodalic acids isolated from Hypogymnia enteromorph (Ach.) Nyl. were tested for mutagenicity in the Ames Salmonella/microsome assay. Physodalic acid exhibited clear doserelated mutagenicity against Salmonella typhimurium strain TA100 with or without S9 mix in both plate‐incorporation and preincubation assays. The addition of S9 mix increased the number of revertants approximately threefold and fourfold in preincubation and plate‐incorporation assays, respectively.
Mutagenicity and chemical analysis of airborne particulates from a rural area in italy
Authors: Reali Daniela , Schlitt Helmut , Lohse Christian , Barale Roberto , Loprieno Nicola 
Published: February 2007

AbstractMutagenic activities of a sample of characterized airborne particulates collected in a rural location near Ispra (Italy) during the summer of 1980 were detected by the Ames test using TA 1537, TA 1538, TA 98, and TA 100 Salmonella strains. Eight chemical classes fractionated from the CH2Cl2 extract of the particulates were bioassayed, and their mutagenicities (TA 98 plus S9) were as follows: organic bases I > polar neutrals > insolubles in cyclohexane > organic acid II > aerosol “in toto” > intermediate neutrals > polycyclic aromatic hydrocarbons > organic acids I > nonpolar neutrals.Periodical samples were taken in the same location from March to December 1981, extracted in dimethyl sulfoxide (DMSO), and directly tested with TA 1537, TA 98, and TA 100 Salmonella strains. For all the strains the mutagenicity varied markedly according to the season, the cold‐month samples being much more mutagenic than the summer‐month samples. The additional of S9 increased the mutagenicity (twofold) of the cold‐month samples. The higher mutagenicity of the samples collected during the cold months could be due to greater amounts of mutagens produced by the combustion processes of domestic heating.
Chromosomal and biochemical studies on the effect of kat extract on laboratory rats
Authors: De Hondt H. A. , Fahmy A. M. , Abdelbaset S. A. 
Published: February 2007

AbstractKat is being used extensively in many countries as a central nervous system stimulant. The effect of three doses of crude kat extract on chromosomal division and abnormalities in bone marrow, as well as on DNA, RNA, and total protein content in brain and liver was studied in laboratory rats in order to test the possible mutagenicity of the drug. Kat was given as a single subcutaneous injection at 0.05 (usage dose), 0.52 (intermediate dose), and 1.00 (sublethal dose) g/kg body weight. Animals were sacrificed at 6, 24, and 48 hr after treatment. Also, some animals were exposed subacutely for 5 consecutive days with sacrifice occurring 6 hr after the last injection. The mitotic index was reduced by all treatments, with the greatest effect occurring in the subacute treatment. Chromosomal abnormalities were induced by kat at all three doses, administered acutely or subacutely. The significant chromosomal aberrations were in the form of gaps, breaks, centromeric attenuations, and centric fusions. The concentration of DNA, RNA, and total protein in liver and brain decreased at all doses, with the greatest decrease occurring after subacute treatment. These findings suggest that kat has a profound effect on cell proliferation, on chromosomal abnormalities, and on DNA, RNA, and total protein synthesis.
In vitro enhancement of the mutagenicity of 4‐nitro‐o‐phenylenediamine by plant S‐9
Authors: Gentile James M. , Gentile Glenda J. , Townsend Steven , Plewa Michael J. 
Published: February 2007

AbstractThe direct‐acting mutagen 4‐nitro‐o‐phenylenediamine (NOP) was activated in vitro by pea or tobacco S‐9 into a more potent mutagen in Salmonella typhimurium strain TA98. NOP mutagenicity was not altered by Aroclor 1254‐induced rat liver S‐9. The plant S‐9 activation of NOP was heat‐sensitive but was not NADPH‐dependent, did not involve superoxide radicals, and was not inhibited by CO. A direct relationship between plant peroxidase and NOP activation was established. Several purified peroxidases including horseradish peroxidase, chloroperoxidase, and lactoperoxidase also activated NOP. The perodoxidative process was not H2O2‐dependent but was partially inhibited by a peroxidase inhibitor.