bluuebunny/crossref_metadata_2025_split huggingface dataset:
Flow cytometric evaluation of cell‐cycle progression in ethyl methanesulfonate and methyl methanesulfonate‐exposed P3 Cells: Relationship to the induction of sister‐chromatid exchanges and cellular toxicity
Authors: Morris S. M. , Domon O. E. , McGarrity L. J. , Kodell R. L. , Casciano D. A. , Morgan W. F. 
Published: February 2007

AbstractIn order to determine the relationships among the reduction in relative cloning efficiency (RCE), sister‐chromatid exchange (SCE) formation, and interference with progression through the cell‐cycle, human teratocarcinoma‐derived (P3) cells were exposed to either ethyl methanesulfonate or to methyl methanesulfonate. The relationship between SCE and toxicity was quantified, the progression through the cell‐cycle was evaluated with flow cytometric methods, and the effects of these chemicals on cell growth and average generation time (AGT) were determined. A strong correlation existed between RCE and SCE (r = −0.978, p < .0001) which was accompanied by an inhibition of growth as evidenced by a significant (p < .0001) negative linear effect of concentration on the relative cell count from 24 to 72 hours after exposure and by a concentration‐dependent increase (p < .0001) in the AGT, Delays in the transit through S‐phase were evident 4 hours after exposure to toxic concentrations of either carcinogen and by 8 to 12 hours post‐exposure at the lower concentrations. Increases in the percentage of nuclei in G2 + M, indicative of G2 arrest, occurred from 12 to 24 hours after exposure. One interpretation of these results is that those effects of EMS and MMS exposure which result in S‐phase delay and G2 arrest may be those elements common to the induction of SCE and cellular toxicity.
Workshop overview: New molecular techniques in genome analysis
Authors: DeMarini David M. , Fuscoe James C. 
Published: February 2007

AbstractAn overview of the application of various molecular techniques to the analysis of genomic DNA is presented. For the analysis of small‐scale changes, the polymerase chain reaction (PCR), colony probe hybridization, mismatch hybridization, and denaturing gradient gel electrophoresis (DGGE) are providing information on mutations within prokaryotic and eukaryotic genes. For large‐scale changes, fluorescence in situ hybridization (FISH), pulsed‐field gel electrophoresis (PFGE), Southern blotting, multiplex PCR, hybridization of linked probes, and restriction enzyme mapping are permitting analysis of genomic alterations that are larger than point mutations but below the resolution of standard cytogenetic analysis. Many of these techniques, either alone or in combination, produce DNA that can be subjected to DNA sequence analysis, which provides the most detailed information regarding genomic changes.
Analysis of mutations using PCR and denaturing gradient gel electrophoresis
Authors: Cariello Neal F. , Swenberg James A. , De Bellis Alessandra , Skopek Thomas R. 
Published: February 2007

AbstractDenaturing gradient gel electrophoresis (DGGE) separates DNA molecules based on primary sequence. Under the appropriate conditions, all base pair (bp) substitutions, frame‐shifts, and deletions less than about 10 bp can be resolved from the wild type sequence using DGGE. Polymerase chain reaction (PCR) permits facile amplification of a given region of the genome. We have combined PCR and DGGE to: (i) Localize mutations in the X‐linked human androgen receptor gene. PCR/DGGE was used to screen the individual exons in the 2757‐bp coding region of the gene in afflicted individuals as well as in potential carriers. Inheritance of a mutant allele has been demonstrated in several cases; (ii) Analyze thousands of thioguanine‐resistant mutants simultaneously. The in vitro mutational spectra of MNNG, ICR‐191, and cisplatin at the human HPRT locus have been examined by this method. The compounds all have mutational hotspots in a GGGGGG sequence in exon 3; however, the particular mutations induced by the agents were different; (iii) Examine the fidelity of several DNA polymerases used in PCR. The fidelity of Thermus aquaticus DNA polymerase (Taq) is 1–2 × 10−4 misincorporations/bp/replication. Problems with Taq polymerase arise in the analysis of complex mutant populations by DGGE because the Taq‐induced errors reduce the sensitivity of the system. To circumvent this, it had been necessary to use Sequenase, a modified T7 DNA polymerase with a higher fidelity. However, Sequenase® is not thermostable and must be added every PCR cycle. A thermostable DNA polymerase from Thermococcus litoralis (Vent) is now available, and we have examined the fidelity of Vent, Taq, and Sequenase® polymerase in PCR using DGGE. The fidelity of Vent, Taq, and Sequenase polymerase was 2.4 × 10−5, 8.9 × 10−5, and 4.4 × 10−5 errors/bp, respectively. Vent polymerase had the highest fidelity of the three enzymes tested.
Direct DNA sequencing of PCR products
Authors: Zimmerman Lisa J. , Fuscoe James C. 
Published: February 2007

AbstractExperiments are described which elucidate some of the technical problems associated with the direct sequencing of polymerase chain reaction (PCR) amplified DNA. Sequencing primer purity, labeling methodology, and template preparation were explored. Conditions are presented for the routine sequencing of single‐ and double‐stranded PCR products.
Factors that affect the molecular nature of germ‐line mutations recovered in the mouse specific‐locus test
Authors: Russell Liane B. 
Published: February 2007

AbstractThe morphological specific locus test (SLT), which allows the scoring of 2,000 loci/hr/person, has been in use for four decades for measuring mammalian germ‐line mutation rates under various conditions of exposure. More recently, the SLT's capabilities for the qualitative characterization of mutations have been exploited. The large sets of mutations centered on specific loci that have been accumulated over the years, including sets of nested deletions, have provided prime material for fine‐structure genetic analyses. Subsequent molecular entry to these regions has led to intensive physical/functional mapping of megabase segments of the genome. In turn, these investigations have generated genetic and molecular tools for analyzing individual mutations as to extent and nature of the genomic lesion. Using the results of such analyses, it has been shown that germ‐cell‐stage at which mutagenic treatment is administered, rather than the nature of the mutagen used, may be the chief determinant of the nature of genomic lesions. These and related quantitative findings now make it possible to optimize conditions for the use of mutagens in providing desired types of mutations as tools (e.g., high incidences of deletions or other rearrangements vs. high incidences of point mutations).
A perspective on measurement of mutations in vivo
Authors: Tennant Raymond W. 
Published: February 2007

AbstractThe development of transgenic mouse lines with target genes that are suitable for tissue‐specific mutagenesis studies is an important contribution to the field of environmental mutagenesis. These models can accommodate many of the questions relating to metabolism, distribution and relative potency of mutagens as well as providing a more comprehensive system for the identification of mutagens. However, the lessons that the field has learned about methods, development and validation from the use of in vitro systems must be applied to the development and validation of transgenic models.
In vivo genotoxicity studies with p‐benzoquinone dioxime
Authors: Westmoreland C. , George E. , York M. , Gatehouse D. 
Published: February 2007

AbstractP‐Benzoquinone dioxime (BQD) appears to be a sex‐specific rat carcinogen inducing tumours of the urinary bladder in female rats. The present paper shows that BQD is a direct‐acting mutagen in Salmonella typhimurium TA98, confirming published data. In contrast to this in vitro data, negative results were obtained after oral administration of BQD to female rats in both the bone marrow micronucleus test and the in vivo liver UDS test.BQD did, however, induce a marked effect upon S‐phase synthesis in the livers of female rats between 14 and 48 hr after a single oral dose of 250 mg/kg. A similar effect was also observed in the livers of male rats. There was no evidence of hepatotoxicity (in terms of elevated liver enzyme levels) after treatment of female rats with the compound indicating that the increase in cell proliferation was due to a direct mitogenic effect of BQD in this organ. Some liver mitogens have been found to be liver carcinogens; this does not appear to be the case for BQD. Nevertheless, the mitogenic activity of this compound might play a contributory role to the induction of bladder cancer in rats if it also acted as a mitogen in this tissue. Further studies are indicated, measuring genotoxicity and cell‐proliferative activity in the bladder in order to further elucidate the mechanism of action of this compound as a rodent carcinogen.
Cytogenetic effects of alachlor and/or atrazine in vivo and in vitro
Authors: Meisner Lorraine F. , Belluck David A. , Roloff Boyd D. 
Published: February 2007

AbstractThe purpose of this study was to assess the cytogenetic effects of two commonly used herbicides, alachlor and atrazine, which are often found together in groundwater. Chromosome damage was examined in bone marrow cells of mice drinking water containing 20 ppm alachlor and/or 20 ppm atrazine, with an immunosuppressive dose of cyclophosphamide used as a positive control. Chromosome damage was also quantified in human lymphocytes exposed in culture to 1.0, 0.1, or 0.01 μg/ml alachlor and/or atrazine. The in vitro study demonstrated dose related cytogenetic damage not associated with mitotic inhibition or cell death, with damage due to the alachlor‐atrazine combination suggesting an additive model. The in vivo study also suggested additive damage due to the alachloratrazine combination after 30 days of treatment, but, unexpectedly, demonstrated less cytogenetic damage and fewer cells with multiple aberrations after 90 days. Also, at 90 days, all treated mice had elevated mitotic indices compared to controls. The fact that the elevated mitotic index was associated with immune suppression in the cyclophosphamide group suggests that death of cells with accumulated chromosomal aberrations resulted in increased bone marrow proliferation, so a higher fraction of cells examined were newer with less damage. Since the alachlor‐atrazine combination treated mice showed little systemic toxicity despite bone marrow mitotic indices similar to the cyclophosphamide treated animals, as well as a similar decrease in cytogenetic damage at 90 days compared to 30 days, cell death and replacement must also be involved but cannot completely explain the results.
Rational approach to the quantification of genotoxicity
Authors: Benigni R. 
Published: February 2007

AbstractThe question of how many and which short‐term tests (STT) are necessary for a satisfactory characterization of the genotoxic properties of chemicals is still open. The answer is important for both basic mutagenicity research and risk assessment. This paper, aimed at giving a rational answer to the problem, analyzes with multivariate statistical methods the data generated by the International Program for the Evaluation of Short‐Term Tests for Carcinogens (IPESTTC). Although it has been found that this data base has a limited reliability for assessing the ability of STTs to predict carcinogenicity, the IPESTTC results are an important source of information on the relationships among different assays, and their ability to identify genotoxic chemicals. A scale of genotoxicity of the chemicals was established by studying with factor analysis their results in 20 IPESTTC tests. The next step of the analysis consisted in the identification of the STT batteries which are the most able to reproduce the genotoxicity scale based on the entire set of STTs. Different batteries were ranked according to their ability to quantify genotoxicity. As a general conclusion, this study indicated that an articulated range of STTs is necessary, and it is not possible to use only one assay (e.g., Salmonella) as an exhaustive indicator of genotoxicity.
Analysis of solvent control and 1‐Nitrosopyrene‐induced chinese hamster ovary cell mutants by southern and northern blots and the polymerase chain reaction
Authors: Newton Ronald K. , Mittelstaedt Roberta A. , Heflich Robert H. 
Published: February 2007

Abstract1‐Nitrosopyrene, a metabolite of the tumorigenic environmental pollutant 1‐nitropyrene, is a potent mutagen at the hprt locus in Chinese hamster ovary (CHO) cells. A single DNA adduct, N‐(deoxyguanosin‐8‐yl)‐1‐aminopyrene, is produced in CHO cells treated with 1‐nitrosopyrene, and this adduct is found in rats and mice exposed to 1‐nitropyrene. In this study, the structure of the hprt gene and the structure and amount of hprt mRNA were analyzed in 43 CHO cell mutants (16 isolated from solvent control cultures and 27 isolated from 1‐nitrosopyrene‐treated cultures). Pstl‐ and BamHl‐digested DNA from the mutants were subjected to Southern blot analysis using a hamster hprt cDNA probe. None of the 1‐nitrosopyrene‐induced mutants and only one of the control mutants displayed hybridization patterns that were different from the parent CHO cells. Northern blot analysis revealed that two control mutants had truncated hprt mRNAs, while 56% of the control mutants and 78% of the induced mutants had reduced levels of hprt mRNA. Using polymerase chain reaction amplification of cDNA synthesized from RNA, the hprt protein‐coding region could be amplified from 23 of the 1‐nitrosopyrene‐induced mutants and 11 of the control mutants. The amplification products from 3 of the control mutants and 5 of the induced mutants were smaller than that found with RNA from parental CHO cells. These results indicate that the mutagenic DNA damage produced by 1‐nitrosopyrene in CHO cells does not cause major structural alterations in the hprt gene and suggest that 1‐nitrosopyrene acts as a point mutagen. A large number of both control and 1‐nitrosopyrene‐induced mutants exhibited a marked reduction in hprt mRNA concentration or possessed truncated mRNA hprt protein coding sequences. These alterations may contribute to the 6‐thioguanine‐resistant phenotype.
Prostaglandin H synthase‐dependent genotoxicity of 2,4‐Diaminotoluene
Authors: Pan Y. H. Laurie , Reddy G. Ramachandra , Reed Gregory A. 
Published: February 2007

Abstract2,4‐Diaminotoluene (2,4‐DAT), a high volume synthetic compound, is moderately carcinogenic to rodents. We report here that 2,4‐DAT is a substrate for the peroxidase activity of prostaglandin H synthase (PHS). In contrast to many aromatic amines which are activated as mutagens by PHS, we find that 2,4‐DAT is not mutagenic to six S. typhimurium strains with this activation system. The strains tested include YG1006, YG1024, and YG1029, which are far more sensitive to the mutagenicity of aromatic amines and nitroarenes than are the standard tester strains. Although not mutagenic itself, 2,4‐DAT does enhance the mutagenicity of 2‐aminofluorene (2‐AF) in the PHS‐catalyzed system in strains TA98, YG1006, and YG1024, with maximal enhancement of 140%, 1831%, and 1216%, respectively. Half‐maximal enhancement of 2‐AF mutagenicity is observed at 15–20 μM 2,4‐DAT for strains YG1006 and YG1024, and about 80 μM for TA98. Studies with compounds structurally related to 2,4‐DAT revealed enhancement of 2‐AF mutagenicity with 2,5‐DAT and o‐phenylenediamine (o‐PD) but not for other DAT isomers, toluidines, and phenylenediamines. Maximal enhancement of 2‐AF mutagenicity observed in TA98 with PHS‐catalyzed activation was 110% for o‐PD and 60% for 2,5‐DAT. This comutagenic effect of 2,4‐DAT appears quite specific for 2‐AF, as it fails to enhance either the PHS‐dependent mutagenicity of the aromatic amines benzidine and 2‐naphthyl‐amine, or the direct mutagenicity of N‐acetoxyacetylaminofluorene,2‐nitrofluorene,4‐nitroquinoline‐N‐oxide and 1,1,1‐trichloropropene‐2,3‐oxide. Enhancement of 2‐AF mutagenicity by 2,4‐DAT is also observed with cytochrome P‐450‐dependent activation, however the half‐maximal 2,4‐DAT concentration was 400 μM, and the maximal enhancement was only 50%. The ability of 2,4‐DAT, under conditions where it is not itself mutagenic, to enhance the genotoxicity of the potent carcinogen 2‐AF comprises an intriguing toxicological interaction, and underscores the inherent difficulties in assessing the genotoxic risks posed by mixtures of compounds.
Evaluation of genotoxicity, pathological lesions, and cell proliferation in livers of rats and mice treated with furan
Authors: Wilson Daniel M. , Goldsworthy Thomas L. , Popp James A. , Butterworth Byron E. 
Published: February 2007

AbstractPreliminary results from the National Toxicology Program (NTP) bioassays of furan given by gavage indicate the induction of hepatocellular carcinomas in male F‐344 rats and in both sexes of B6C3F1 mice, and cholangiocarcinomas in both sexes of rats. To assess the genotoxicity of furan, chemically induced unscheduled DNA synthesis was evaluated in the in vivo hepatocyte DNA repair assay. Furan did not induce unscheduled DNA synthesis in hepatocytes isolated after single gavage treatment of male F‐344 rats (5, 30, and 100 mg/kg) or male B6C3F1 mice (10, 50, 100, and 200 mg/kg). Furan induced cytotoxicity and enhanced cell proliferation were evaluated in livers of rats and mice as events that also might give rise to mutations and/or drive tumor formation. The labeling index (Ll, percentage of hepatocyte nuclei in S‐phase) was measured histoautoradiographically following a single gavage administration of furan (30 mg/kg, male rats; 50 mg/kg, male mice) followed by an injection of 3H‐thymidine 2 hr prior to sacrifice. Hepatocellular necrosis and a sharp increase in Ll (23.9 for mice and 17.8 for rats vs. less than 0.5 for controls) was observed 48 hr after treatment with furan, indicative of restorative cell proliferation secondary to cytotoxicity. Hepatocyte proliferation was evaluated also at the highest NTP bioassay dose (15 mg/kg/day for mice and 8 mg/kg/day for rats, 5 days/week) by labeling with 3H‐thymidine administered via a 6 day osmotic pump implanted subcutaneously. Necrosis and inflammation were observed along the subcapsular visceral surface of the left or caudate liver lobes, likely due to diffusion of furan directly through the stomach to the liver. After 6 weeks of furan administration, male and female rats, but not mice, exhibited bile duct hyperplasia as well as metaplasia in the areas of fibrosis along the subcapsular visceral surface of the left or caudate liver lobes. The fold increase in hepatocyte Ll in treated animals relative to the combined controls measured at weeks 1, 3, and 6 ranged from 39 to 5 for male mice, 18 to 51 for male rats, and 12 to 19 for female rats. Taken together, these data suggest that mechanisms other than direct DNA‐reactivity might explain the profile of oncogene mutations observed in the mouse liver tumors, including selective promotion of different subpopulations of preneoplastic cells and/or mutational events secondary to sustained cell proliferation or inflammation. The extensive amount of furan‐induced cell proliferation subsequent to cytotoxicity likely had a significant impact on tumor development, and such data should be considered in risk evaluations for this compound.
Mutagenicity of benzo(a)pyrenyl‐1‐sulfate in the Ames test
Authors: Irwin Susan E. , Kwei Gloria Y. , Blackburn Gary R. , Thurman Ronald , Kauffman Fredrick C. 
Published: February 2007

AbstractComparison of the mutagenicity of nine isomeric benzo(a)pyrenyl [B(a)P] phenols conjugated with either sulfate or glucuronide was carried out using strain Salmonella typhimurium TA98. Of the nine conjugates tested, only B(a)P‐1‐sulfate was mutagenic. Accordingly, the mutagenicity of B(a)P‐1‐sulfate was compared with that of B(a)P and 1‐hydroxybenzo(a)pyrene [B(a)P‐1‐OH] in the presence and absence of rat lung S9 and Aroclor‐induced liver S9 with and with out an NADPH‐generating system. B(a)P‐1‐sulfate was slightly mutagenic, whereas B(a)P and the 1‐hydroxy derivative were nonmutagenic when S9 fractions and NADPH were omitted. Addition of induced liver S9 with NADPH caused mutagenicity with B(a) ‐1‐OH>B(a)P>B(a)P‐1‐sulfate. B(a)P‐1‐sulfate was the only mutagenic species when lung S9 was added. This mutagenicity did not require NADPH. Sodium sulfite, an inhibitor of arylsulfatase, decreased the mutagenicity of B(a)P‐1‐sulfate. These data suggest that a unique mutagenic species is generated from B(a)P‐1‐sulfate via arylsulfatase in rat lung.
Genotoxicity of chryseno[4,5‐bcd]thiophene and its sulfone derivative
Authors: Sinsheimer J. E. , Hooberman B. H. , Das S. K. , Savla P. M. , Ashe A. J. 
Published: February 2007

AbstractOur recent syntheses of chryseno[4,5‐bcd]thiophene together with its potential sulfone metabolite, chryseno[4,5‐bcd]thiophene‐4,4‐dioxide, have made these compounds available for genotoxicity testing. Such toxicity testing is of interest as this thiophene is an isoster of the established carcinogen benzo[a]pyrene and is one of the thiaarenes which are potential environmental contaminants found in fossil fuels. Although the thiophene was less mutagenic than benzo[a]pyrene in Salmonella strains TA98 and TA100 after S9 activation, it exhibited in vivo chromosomal aberration activity equal to that of benzo[a]pyrene in the bone‐marrow cells of mice. A reduced activity with Salmonella as well as in the bone‐marrow cell assay for the sulfone does not support its role as the key active metabolic intermediate for the genotoxicity of the thiophene. Our molecular orbital calculations would be consistent with the concept of activation through a diol‐epoxide mechanism and of fers an explanation for the reduced genotoxicity of the sulfone via this mechanism. These genotoxicity studies support the concern that sulfur isosters of established carcinogenic polycyclic aromatic hydrocarbons could themselves be toxic.
Detection of direct‐acting mutagens in ambient air: A comparison of two highly sensitive mutagenicity assays
Authors: Houk Virginia S. , Goto Sumio , Endo Osamu , Claxton Larry D. , Lewtas Joellen , Matsushita Hidetsuru 
Published: February 2007

AbstractAmbient air has been shown to contain numerous hazardous pollutants, many of which are known or suspected carcinogens and mutagens. Bioassays play a prominent role in the characterization of these genotoxic pollutants, and as new test methods are developed, it is incumbent upon researchers to evaluate assay performance and report relative merits. In this study, two Salmonella test methods (the spiral and pre‐incubation assays) were assessed to determine their usefulness as screening methods for monitoring direct‐acting mutagens in ambient air. The spiral assay automates the conventional plate‐incorporation assay and has been shown to reduce the labor, materials, and sample mass required to perform mutagenicity testing. The preincubation assay has been shown to enhance test sensitivity for certain classes of compound, thereby reducing the amount of sample required for dose‐response analysis. Both assays were used to test organic extracts of airborne particulate matter collected in Tokyo during the winters of 1988 and 1990. In addition to the conventional tester strains TA98 and TA100, two newly developed YG strains were evaluated. Strains YG1024 and YG1029—derived from TA98 and TA100, respectively—contain an acetyltrans‐ferase plasmid that confers upon the strains greater sensitivity towards nitroarenes. Results from this study indicated that both assays were able to detect direct‐acting mutagens in the Tokyo air samples. The mutagenic activity associated with the samples was directly related to the particle mass present in a given volume of air. Mutagenic response was greater in the spiral assay relative to the preincubation assay, especially when YG tester strains were used. The YG strains were significantly more sensitive to mutation than the TA strains in both assays, which suggests that nitroaromatics are an important class of genotoxic contaminant present in Tokyo air. © 1992 Wiley‐Liss, Inc.