bluuebunny/crossref_metadata_2025 huggingface dataset:
Induction of sister chromatid exchange in spleen and bone marrow cells of rats exposed by inhalation to different dose rates of ethylene oxide
Authors: Ong T. , Bi H.‐K. , Xing S. , Stewart J. , Moorman W.
Published: February 2007

We investigated the effects of dose rate on the frequency of sister chromatid exchange (SCE) in bone marrow and spleen cells of rats exposed to ethylene oxide (EtO). Four groups (18/group) of male Fischer 344 rats were exposed to EtO by inhalation. The exposures consisted of 100 ppm for 6 hr/day, 300 ppm for 2 hr/day, 600 ppm for 1 hr/day, and clean air control. All EtO treated rats were given a total exposure dose of 600 ppm‐hr daily, 5 days/week for 3, 6, or 9 months. Six rats per group were sacrificed at each time point, and SCEs were measured in cultured spleen and bone marrow cells. A statistically significant increase was found in SCEs in both bone marrow and spleen cells for all treated groups and at each time point when compared to the control, except at the 3‐month exposure for the middle and high dose‐rate groups in bone marrow cells. In the spleen, the increases in SCEs were similar among the three experimental groups. In bone marrow, the lowest dose rate (100 ppm) resulted in higher SCE frequencies than the medium and high dose‐rate group after 3 and 6 month exposures. The overall frequencies of SCEs in the spleen cells were higher than in the bone marrow cells. The increase in SCE frequencies and decrease in the replicative index in spleen cells were also dependent on the duration of exposure. These results indicate that (1) EtO, by inhalation, can cause SCEs both in spleen and bone marrow cells of Fischer 344 rats, (2) spleen cells are more sensitive to EtO than bone marrow cells, and (3) in bone marrow cells the lowest dose‐rate (longest) exposure causes more SCEs than the highest dose‐rate (shortest) exposures. © 1993 Wiley‐Liss, Inc.
Antimutagenic potency of chlorophyllin in the salmonella assay and its correlation with binding constants of mutagen‐inhibitor complexes
Authors: Dashwood Roderick , Guo Dexin
Published: February 2007

Chlorophyllin (CHL) is a water‐soluble salt of chlorophyll that exhibits antimutagenic activity in short‐term genotoxicity assays and inhibits carcinogen‐DNA binding in vivo. The antimutagenic potency of CHL was studied against several structurally related heterocyclic amines using the Salmonella assay. The mutagens included 2‐amino‐3‐methylimidazo[4,5,‐f]‐quinoline (IQ) and seven related IQ‐type compounds, and 3‐amino‐1‐methyl‐5H‐pyrido[4,3‐b]indole (Trp‐P‐2) and three additional non‐IQ‐type compounds. No relationship was observed between mutagenic potency (revertants/ng mutagen) and antimutagenic potency when expressed in terms of the CHL dose/plateinhibiting mutagenicity by 50 percent (l50). However, a correlation was observed between mutagenic potency and the mole ratio of CHL to mutagen giving 50% inhibition (MR50), with most mutagens requiring several hundredfold to several thousandfold molar excess of CHL for inhibition. In spectrophotometric studies, CHL formed noncovalent molecular complexes with the heterocyclic amines, with binding constants in the range 3–13 x 103 M−1. Binding constants were inversely correlated with l50 and MR50 values, i.e., with increasing strength of complex formation less CHL/plate and a lower mole ratio of CHL to mutagen was required to inhibit mutagenicity. The results support an inhibitory mechanism in which chlorophylls operate as “interceptor molecules,” interacting with carcinogens and mutagens directly and limiting their bioavailability. © 1993 Wiley‐Liss, Inc.
Test of chiral recognition in the salmonella typhimurium (TA100) mutagenicity of mucochloric acid‐cysteine adducts
Authors: Lalonde Robert T. , Xie Shan , Bu Lin
Published: February 2007

A difference in biological response to enantiomers is not an uncommon observation and is, therefore, to be expected in various manifestations of genotoxicity. The bacterial mutagen mucochloric acid (2,3‐dichloro‐5‐hydroxy‐2(5H)‐furanone) has one chiral center, at C‐5, but this mutagen exists in racemic form because of the facile stereoisomerization occurring by the mechanism of ring‐chain tautomerism. Two readily synthesized enantiomeric analogs of mucochloric acid, as well as the racemic form of the two, were prepared from mucochloric acid and (R)‐(+)‐, (S)‐(‐)‐, and (R,S)‐(+/‐)‐cysteine. Using Salmonella typhimurium (TA100), the enantiomeric compounds were assayed together in four dose/response assays along with mucochloric acid, the reference mutagen. In three of the same four assays, the racemic form was also assayed. Neither statistically significant differences in mutagenicity, as determined in slope responses, nor distinctions from the plotted curves were observed among the two enantiomers and their racemic form. Therefore, no enantiospecific interaction between enantiomers and chiral DNA or enzymes involved in repair or replication could be concluded. © 1993 Wiley‐Liss, Inc.
Evidence for excision repair‐dependent and independent processes in ara C‐induced chromosome rearrangements in G1 human lymphocytes
Authors: Kishi Kunikazu , Sekizawa Koichi
Published: February 2007

1‐β‐D‐arabinofuranosylcytosine (ara C) enhances the formation of chromosome rearrangements such as translocations or dicentric chromosomes in G1 cells containing DNA lesions. The formation of rearrangements is hypothesized to be the result of inhibition of excision repair. Ara C has also been known to lead to the formation of chromosome rearrangements in G1 cells in the absence of induced DNA lesions. It is not known whether a common mechanism is involved in these two processes. In the present study, we used excision repair‐deficient XP cells to investigate whether excision repair is involved in the formation of chromosome rearrangements in G1 cells which do not contain induced DNA lesions.

G0 Lymphocytes from an XP patient were either treated with 4‐nitroquinoline‐1‐oxide (4NQO) or left untreated. Cells were then cultured in the presence of ara C for about 18 h. Aphidicolin (APC), which induces chromosome rearrangements in cells containing 4NQO‐induced DNA lesions, was used for comparison. The resulting frequency of dicentrics and rings (dic & ring) was determined at the first mitoses after culture initiation. In 4NQO‐pretreated XP cells, the frequency of dic & ring was not increased by post‐treatment with ara C or with APC. This result is thought to reflect the absence of excision repair in XP cells. However, normal induction of dic & ring was observed in XP cells not pretreated with 4NQO but treated with ara C.

Thus, there seems to be two different processes involved in the induction of G1 rearrangements: excision repair‐dependent and excision repair‐independent. UV‐endonuclease is not involved in excision repair‐independent rearrangements.
Contribution of O6‐alkylguanine and N‐alkylpurines to the formation of sister chromatid exchanges, chromosomal aberrations, and gene mutations: New insights gained from studies of genetically engineered mammalian cell lines
Authors: Kaina Bernd , Fritz Gerhard , Coquerelle Therese
Published: February 2007

O6‐methyl‐ and O6‐ethylguanine are the major premutagenic and precarcinogenic lesions induced in DNA by monofunctional alkyiating agents, albeit formed in minor amounts. The involvement of these lesions in SCE and aberration formation is less clear. We have analyzed the contribution of O6‐alkylguanine to SCE and aberration formation, as well as its toxic and point mutation inducing effect in transgenic Chinese hamster ovary (CHO) cell lines that express variable amounts of human O6‐methylguanine‐DNA methyltransferase (MGMT). Cells that overexpress MGMT (or the bacterial Ada protein) gained resistance to the formation of alkylation‐induced SCEs and aberrations, as compared to MGMT deficient cells. A correlation was apparent between the level of protection for SCEs and cell killing, indicating that both phenomena are interrelated. The protective effects were dependent on the level of MGMT expression, the agent used for alkylation, and cell cycle progression. Our data suggest that at least 2 kinds of lesions are responsible for SCE and aberration formation, namely, O6‐alkylguanine and one or various N‐alkylation products. The probability that O6‐methylguanine is converted into cytogenetic effects has been estimated to be about 1:30 for SCEs, and 1:147,000 and 1:22,000 for chromosomal aberrations in the first and second post‐treatment mitosis, respectively. The induction of SCEs and likely also of aberrations by O6‐methylguanine requires two replication cycles and is supposed to involve the formation of secondary DNA lesions. Increased repair of 3‐methyladenine and 7‐methylguanine in CHO cells that overexpress the N‐methylpurine‐DNA glycosylase (MPG) after transfection with the human MPG‐cDNA did not give rise to protection against methylation‐induced SCEs and aberrations, probably because of incomplete excision repair. MPG overexpressing cells reacted even more sensitively to methylating agents, suggesting apurinic sites formed as a result of MPG action to be SCE and aberration‐inducing lesions. © 1993 Wiley‐Liss, Inc.
Predominant induction of kinetochore‐containing micronuclei by extracts of diesel exhaust particulates in cultured human lymphocytes
Authors: Odagiri Youichi , Zhang Jian‐Xin , Uchida Hiroyuki , Kawamura Ken , Adachi Shuichi , Takemoto Kazuo
Published: February 2007

The aneuploidy‐inducing activity of extracts of diesel exhaust particulates from light duty (LD) and heavy duty (HD) engines was investigated in cultured peripheral blood lymphocytes of 8 healthy donors using the cytokinesis‐block micronucleus test with the kinetochore labelling modification. A majority of the subjects tested showed a significant kinetochore‐positive micronucleus induction after treatment with the highest dose (150 μg/ml) of LD extract, although some subjects also showed induction of kinetochore‐negative micronuclei. Only one subject had significantly increased numbers of kinetochore‐positive micronuclei at a dose of 400 μg/ml of HD extract. These results suggest that diesel extract, at least LD extract, possesses the ability to induce whole chromosome loss (aneuploidy) preferentially, although there are also chromosome breaks. © 1994 Wiley‐Liss, Inc.
Absence of formation of benzo[a]pyrene/DNA adducts in the cuttlefish (sepia officinalis, mollusca: Cephalopoda)
Authors: Lee Phillip G. , Lu Lee‐Jane W. , Salazar James J. , Holoubek Viktor
Published: February 2007

Benzo[a]pyrene (B[a]P) injected intramuscularly into the base of the arms of cuttlefish was released continuously from the injection site and removed from the organism. Only a portion of the compound accumulated in the body. Twenty‐four hr after its injection, 75% of B[a]P applied in olive oil was removed from the cuttlefish, and 1.2% was found in the body outside the head, the site of injection. If the carcinogen was dissolved in dimethylformamide, the removal of B[a]P was slower, so that only 18% of the injected B[a]P was removed from the organism and 0.36% accumulated in the body outside the head 24 hr after injection. The high level of B[a]P in gills and hemolymph 4 hr after injection and the kinetics of the decrease of its concentration with time indicate that these two organs could be involved in the excretion of B[a]P from the body. The B[a]P/DNA adducts characteristic for vertebrates could not be demonstrated in gills, skin, brain, hepatopancreas, and lymphocytes of the cuttlefish 24 hr after injection of B[a]P. The dose of the carcinogen injected into the cuttlefish was 2—4 times higher than the dose resulting in the formation of a high level of B[a]P/DNA adducts in the vertebrates. A different metabolism of B[a]P in the tissue of cephalopods, compared to vertebrates, could be less favorable to the process leading to malignant transformation and could explain the absence from the literature of reports of tumors in cephalopods. © 1994 Wiley‐Liss, Inc.
Negative dose‐response relationship for radiation‐induced micronuclei in polychromatic erythrocytes of mice
Authors: McFee A. F. , Cook S. B. , Abbott M. G.
Published: February 2007

Micronuclei were assessed among the bone marrow PCEs of mice 28 hr after exposures to 1 to 8 Gy of X‐rays and at 6‐hr intervals from 12‐60 hr after exposures to 2 or 6 Gy. At 28 hr, the frequency of micronuclei declined as the exposure level increased from 1 to 8 Gy. The peak proportion of micronucleated PCEs appeared much later following 6 Gy than after 2 Gy exposures, implicating cell cycle delay as the cause of the negative dose‐response relationship.
Chromosome aberration, sister‐chromatid exchange, proliferative rate index, and serum thiocyanate concentration in smokers exposed to low‐dose benzene
Authors: Major J. , Jakab M. , Kiss Gabriella , Tompa Anna
Published: February 2007

Cytogenetical endpoints, i.e., chromosome aberration (CA), sister‐chromatid exchange (SCE), and proliferative rate indexes (PRI), were measured in peripheral blood lymphocytes (PBL) of 42 workers exposed occupationally to low‐dose benzene, and of 42 controls. The role of smoking habit as a confounding factor of genotoxic effects caused by occupational low‐dose benzene exposure was also studied. The benzene concentrations in the ambient air samples varied from 3 to 20 mg/m3 (mean: 7 mg/m3). The continuous low‐dose benzene exposure significantly increased the CA and SCE frequencies, but did not influence PRI. Smoking levels were characterized by subjective accounts and by serum thiocyanate concentrations (SCN). CA and SCE were not significantly increased in smokers compared to nonsmokers, but the differences were expressed to a greater extent in the case of measurement of SCN concentrations. Determination of SCN proved to be more objective in the assessment of genotoxic effects of smoking as a confounding factor of occupational low‐dose benzene exposure. © 1994 Wiley‐Liss, Inc.
Comparative investigations of the genotoxic effects of metals in the single cell gel (SCG) assay and the sister chromatid exchange (SCE) test
Authors: Hartmann Andreas , Speit Günter
Published: February 2007

Sodium arsenite (NaAsO2) and cadmium sulphate (CdSO4) were tested for their ability to induce genotoxic effects in the single cell gel (SCG) assay and the sister chromatid exchange (SCE) test in human blood cultures in vitro. Both metals induced DNA damage in white blood cells that was expressed and detected as DNA migration in the SCG assay. Dose dependent effects were seen for cadmium in concentrations from 5 × 10−4‐5 × 10−3 M and for arsenic in concentrations from 2 × 10−4‐1.5 × 10−3 M. The distribution of DNA migration among cells, a function of dose, revealed that the majority of exposed cells expressed more DNA damage than cells from control cultures and that with increasing length of DNA migration the variability in migration among cells increased as well.

Treatment of cells for 2 hr or 24 hr beginning 48 hr after the start of the blood cultures did not increase the SCE frequency in the case of cadmium but caused a small but significant SCE induction with arsenic at the highest concentration. The metal concentrations which could be investigated in the SCE test were much lower due to a strong toxic effect. Metal concentrations which were toxic in the SCE test were without visible effect in the SCG assay. Thus the two endpoints for the determination of genotoxic effects in vitro differed markedly with respect to the detection of genotoxicity induced by metals. These differences and the biological significance of the findings are discussed. © 1994 Wiley‐Liss, Inc.
Detection of genotoxic effects in human gastric and nasal mucosa cells isolated from biopsy samples
Authors: Pool‐Zobel Beatrice L. , Lotzmann Natalie , Knoll Martin , Kuchenmeister Frank , Lambertz Renate , Leucht Ullrich , Schröder Hans‐GÜNther , Schmezer Peter
Published: February 2007

To assess genotoxic burdens from chemicals, it is necessary to relate observations in experimental animals to humans. The success of this extrapolation would be increased by including data on chemical activities in human tissues. Therefore, we have developed techniques to assess DNA damage in human gastric and nasal mucosa (GM, NM) cells. Biopsy samples were obtained during gastroscopy from macroscopically healthy tissue of the stomach or from healthy nasal epithelia during surgery. The specimens were incubated for 30–45 min at 37°C with a digestive solution. We obtained 1.5–8 × 106 GM cells and 5–10 × 105 NM cells per donor, both with viabilities of 80–95%. The cells were incubated in vitro for 1 hr at 37°C with the test compounds added in their appropriate solvents. In GM cells, we studied N‐methyl‐N'‐nitro‐N‐nitrosoguanidine (MNNG), sodium dichromate (Na2Cr2O7), nickel sulphate (NiSO4), cadmium sulphate (CdSO4), and lindane. In NM cells, lindane was investigated. Each compound was assessed for DNA damaging activity in cells of at least three different human donor samples using the microgel single cell assay. Similar studies were performed with GM and NM cells obtained from Sprague‐Dawley rats. We have found human GM cells to be more sensitive to the genotoxic activity of MNNG than rat GM cells (low effective concentration [LEC] = 0.16 and 0.625 μg/ml for human and rat, respectively). Human cells were also more sensitive to the cytotoxic/genotoxic activity of NiSO4 (LEC = 5 and 19 μmoles/ml for human and rat, respectively). CdSO4 was genotoxic in human GM cells (LEC = 0.03–0.125 μmoles/ml), whereas no dose‐related genotoxicity was observed in rat GM at concentrations up to 0.5 μmoles/ml. In contrast, approximately equal responses regarding genotoxicity and cytotoxicity were observed in rat and human GM for Na2Cr2O7 (0.25–1 μmoles/ml). Lindane, however, was genotoxic in three out of four rat GM but not in human GM cells (0.5–1 μmoles/ml), whereas it was active in both rat and human NM cells. Together with other recently published in vivo findings, our results with lindane can be interpreted according to a parallelogram approach. In view of possible human exposure situations and the sensitivities of the two target tissues from both species, the data imply that lindane will pose a health risk to humans by inhalation but not by ingestion. © 1994 Wiley‐Liss, Inc.
Micronucleus induction in cytokinesis‐blocked mouse bone marrow cells in vitro following in vivo exposure to x‐irradiation and cyclophosphamide
Authors: Odagiri Youichi , Takemoto Kazuo , Fenech Michael
Published: February 2007

A cytokinesis‐block micronucleus (MN) method for the simultaneous but separate measurement of chromosome damage in erythroid and myeloid bone marrow cells is described. MN induction in cytokinesis‐blocked mouse bone marrow cells in vitro following in vivo exposure to x‐ray or cyclophosphamide (CP) was investigated. Immediately after whole body irradiation with acute doses of either 0, 1, 2 or 4 Gy x‐rays, or 2 hr after treatment with either 0, 12.5, 25, or 50 mg CP/kg body weight, bone marrow cells were collected and then cultured in medium supplemented with 3.0 μ/ml cytochalasin B for 24 hr. The binucleated cells were scored in erythroid, myeloid, lymphoid and other cells.

The myeloid/erythroid (M/E) ratio was decreased by x‐irradiation or CP treatment in a dose‐dependent manner. The dividing index (DI; binucleated cells/binucleated + mononucleated cells; %) was decreased in both eryth‐roid and myeloid cells in the same manner. Dose‐dependent increases in MN frequency were observed following x‐irradiation in both erythroid and myeloid cells. A similar dose‐dependent MN induction was observed with CP. The MN frequency in myeloid cells was much greater than in erythroid cells (about 4‐fold following 4 Gy exposure, and more than 10‐fold after 50 mg/kg CP). Lymphoid and other cells were not suitable for scoring DI and MN frequency because of insufficient numbers of binucleated cells. These results suggest that micronuclei can be identified in both myeloid and erythroid cells and that myeloid cells are more susceptible to x‐ray or CP‐induced chromosomal damage than erythroid cells as expressed by MN induction. © 1994 Wiley‐Liss, Inc.
Induction of DNA damage by urethane in mouse testes: DNA binding and unscheduled DNA synthesis
Authors: Sotomayor Rene E. , Sega Gary A. , Kadlubar Fred
Published: February 2007

The extent and persistence of DMA damage and repair were investigated in mouse spermatogenic cells exposed in vivo to urethane (ethyl carbamate, EC). Adult male mice exposed to [3H]EC at 10–1,000 mg/kg were sacrificed 12 hr later. EC/metabolite binding to liver and testicular DNA and to sperm heads from the vasa deferentia was measured. Other male mice were exposed to EC at 50–750 mg/kg, and unscheduled DNA synthesis (UDS) induction was investigated in early spermatid stages. Similar experiments were conducted with vinyl carbamate (VC; putative EC metabolite) at 10–75 mg/kg. [3H]EC bound to liver and testicular DNA and to whole sperm heads. Testicular DNA binding increased linearly with dose, although binding was at least 2 orders of magnitude lower than with liver DNA. Sperm head binding also increased linearly with dose. Dose response studies with the UDS assay showed that EC and VC induced a small but significant increase of the UDS response in early spermatid stages. However, the induced UDS responses were quite variable and did not consistently increase with the administered dose. To determine the time kinetics of UDS induction, [3H]dThd was injected at various times after treatment with 500 mg/kg of EC or 60 mg/kg of VC. A slight but significant UDS increase was observed 4 hr after treatment with EC but not with VC. Overall, these results suggest that EC metabolites bind to testis DNA and cause low‐level DNA damage in mouse sper‐matogenic cells. This type of DNA damage apparently does not have significant genetic consequences. © 1994 Wiley‐Liss, Inc.
Molecular models that may account for nitrous acid mutagenesis in organisms containing double‐stranded DNA
Authors: Hartman Zlata , Henrikson Erik N. , Hartman Philip E. , Cebula Thomas A.
Published: February 2007

Nitrous acid (NA) is often presumed to cause base substitutions in organisms with double‐stranded DNA as a direct consequence of oxidative deamination of adenine and of cytosine residues. Here we summarize evidence indicating that other mechanisms are involved in the case of NA‐induced G/C→A/T transition mutations. We present several models for pathways of NA mutagenesis that may account for our experimental results and overlapping data noted in the literature. One model proposes that the base substitution mutations observed are due to DNA alkylation damage mediated via nitrosation of polyamines and/or other ubiquitous cellular molecules. Other models assume that pre‐disposing lesions, such as G‐to‐G cross‐links, are first formed. The cross‐links are pictured as leading to perturbations in DNA structure that allow subsequent opportunity for NA‐induced deaminations of cytosine residues in their immediate vicinity. The deaminations preferentially result in G/C→A/T transition mutations at sites highly dependent on adjoining base sequence context (i.e., in NA “mutational hotspots”). A final model proposes that NA‐induced G/C→A/T transition mutations arise mainly from oxidative deamination of guanosine residues and not from deamination of cytosine residues in duplex DNA. © 1994 Wiley‐Liss, Inc.
Localization of the xanthine guanine phosphoribosyl transferase gene (gpt) of E. coli in AS52 metaphase cells by fluorescence in situ hybridization
Authors: Michaelis Kevin C. , Helvering Leah M. , Kindig Delinda E. , Garriott Michael L. , Richardson Katherine K.
Published: February 2007

The purpose of this study was to localize the xanthine guanine phosphoribosyl transferase gene (gpt) to a specific chromosome to investigate its proposed autosomal location in the AS52 cell line. AS52 cells are hgprt‐deficient Chinese hamster ovary (CHO) cells which carry a single functional copy of the E. coli gpt gene. Fluorescence in situ hybridization (FISH) and digoxigenin‐labeled probes, as small as 673 bp, were used in an attempt to localize the 456 bp gpt gene to a specific chromosome. Chi‐square analysis of 13 metaphases showed significant labeling on autosomal chromosomes 6 or 7, which are indistinguishable without further banding analysis. Furthermore, a majority of the signals were on the q arm, proximal to the centromere. The data collected supports incorporation of the gpt gene into an acrocentric autosome of the AS52 cell line. © 1994 Wiley‐Liss, Inc.
Reduction of benzene toxicity by toluene
Authors: Plappert U. , Barthel E. , Seidel H. J.
Published: February 2007

BDF1 mice were exposed in inhalation chambers to benzene (900 ppm, 300 ppm) and/or toluene (500 ppm, 250 ppm) 6 hr per day, 5 days per week, for up to 8 weeks. Benzene alone induced a slight anemia after 4 and 8 weeks and a reduction of BFU‐E and CFU‐E numbers in the marrow. The coexposure to toluene reduced the degree of anemia. These results confirm previous studies where toluene was found to reduce benzene toxicity. This protective effect was most pronounced when DNA damage was studied in peripheral blood cells, bone marrow, and liver using the single cell gel (SCG) assay. With benzene alone, either with 300 or 900 ppm, a significant increase in DNA damage was detected in cells sampled from all three organs. Toluene alone did not induce a significant increase in DNA damage. The coexposure of benzene and toluene reduced the extent of DNA damage to about 50% of benzene alone. This result is considered a clear indication for a protective effect of toluene on the genetic toxicity of benzene. © 1994 Wiley‐Liss, Inc.
Enhancement of the mutagenicity of amino acid pyrolysates by phthalate esters
Authors: Sato Takahiko , Nagase Hisamitsu , Sato Kayoko , Niikawa Miki , Kito Hideaki
Published: February 2007

The ability of phthalic acid, phthalic acid anhydride, and various phthalate esters to enhance the mutagenicity of many amino acid pyrolysates was observed with the Ames test (Salmonella typhimurium TA98), but not the SOS Chromotest. Phthalate enhancement of the mutagenicity of 4‐nitroquinoline‐1‐oxide, 2‐nitrofluorene, and benzo[a]pyrene was not observed with either test. The mutagenicity‐enhancing ability may be related to the induction of enzymes such as P450IIB, that metabolize amino acid pyrolysates. By quantitative structure activity relationship (QSAR) analysis, a good correlation was observed between the mutagenicity‐enhancing activity of phthalates and their octanol‐water partition coefficients. © 1994 Wiley‐Liss, Inc.
Improved prediction of carcinogenic potencies from mutagenic potencies for chemicals positive in rodents and the ames test
Authors: Bogen Kenneth T.
Published: February 2007

Most studies of correlation between logs of mutagenic potency (MP) and cancer potency (CP) have obtained relatively small but statistically significant estimates of correlation (r) and corresponding log‐log slope (b, in Log[CP] = a + b Log[)MP]). But for mutagenic carcinogens, multistage cancer theory predicts that b and r should be highest when MP values best estimate mutation yields per unit dose at concentrations at least as high as those observed to cause cancer in bioassay animals. To test this hypothesis, the correlation of Ames test and rodent cancer potencies was examined for a total number n of 134 chemicals reported as positive in both assays. Values of maximum significant cancer potency (CP, in [mmol/kg‐day]−1) were obtained from a published carcinogenic potency database. Values of maximum mutagenic potency (MP, as revertants per mmol/L‐plate) were estimated from 2,347 sets of Ames test data reported by the NTP mutagenicity testing program, supplemented by similar data newly obtained for ten heterocyclic amines. For compounds with one or more significantly positive MP estimates based on approximately linear Ames test dose‐response data, linear regression of maximum values of Log(CP) on Log(MP) yielded b = 0.27 ± 0.065 and r = 0.39 (P = 0.0001, n = 105), similar to previously reported results for relatively large n. As predicted, when MP values were additionally restricted to include only values estimated from Ames test data approximately linear at corresponding lowest‐TD50 concentrations, similar regressions yielded significantly improved fits (e.g,. b and r = 0.6, P < 10−7, n = 68). Implications of these findings are discussed concerning the quantitative role that mutations like those measured in the Ames test may have in explaining observed cancerbioassay results. © 1995 Wiley‐Liss, Inc.
Relative genotoxic activities of pesticides evaluated by a modified SOS microplate assay
Authors: Venkat J. A. , Shami S. , Davis K. , Nayak M. , Plimmer J. R. , Pfeil R. , Nair P. P.
Published: February 2007

The genotoxic activities of 47 pesticides were determined using a modified SOS microplate assay in which the induction of β‐galactosidase in E. coli PQ37 was used as a quantitative measure of genotoxic activity. The results were compared with those obtained with anethole, curcumin, and capsaicin, a few examples of naturally occurring compounds present in foods. The assays were conducted with pesticides dissolved either in a suitable solvent, such as 10% DMSO in physiological saline or dispersed in sodium taurocholate micelles, to simulate conditions in the small intestine from where these substances are normally absorbed from the diet. 4‐Nitro‐quinoline oxide (4–NQO) served as the reference standard of a direct acting mutagen. In micellar form, 4–NQO and 25 of the 47 pesticides tested showed significantly higher genotoxic activities than when they were tested in an organic solvent. In micellar form the SOS inducing potency of 4–NQO was almost twice as high as in 10% DMSO in physiological saline. In taurocholate micelles, the five most active compounds had activities in the range of 1,234–3,765 units/μmol and in the order of decreasing activities they were ranked as follows: malathion > dichlorvos > lindane > chlordane > endrin. They were significantly less active than 4–NQO (less than 40%). In micellar solution the naturally occurring compounds, anethole, curcumin, and capsaicin gave activities of 4,594, 928, and 809 units/μmol, respectively. These studies show that genotoxicity may depend upon the environment in which cells are exposed to these potential genotoxins. It appears that testing of the more hydrophobic compounds, both synthetic and naturally occurring, are needed. © 1995 Wiley‐Liss, Inc.
Frameshift mutations in salmonella induced by the extracts of medicinal herbs Lannea edulis (sond.) engl. and Monotes glaber sprague
Authors: Sohni Youvraj R. , Davis Cheryl L. , Deschamps Adrian B. , Kale P. G.
Published: February 2007

Lannea edulis an(d Monotes glaber have been prescribed for various affectations in the traditional medical practice of Zimbabwe and other parts of Africa. Mutagenicity testing using Salmonella typhimurium strains TA97a, TA98, and TA100, indicated that the aqueous extracts of these plants induced frameshift mutations in Salmonella. The extract of L. edulis displayed marginal mutagenicity in strain TA97a while that of M. glaber showed a significant dose‐dependent mutagenicity in both strains TA97a and TA98. There was no mutagenic effect observed in strain TA100. Two other plant extracts, those of Lannea discolor and Dolichos kilimandscharicus, were nonmutagenic in all three strains. © 1995 Wiley‐Liss, Inc.
1‐nitropyrene as a marker for the mutagenicity of diesel exhaust‐derived particulate matter in workplace atmospheres
Authors: Scheepers Paul T. J. , Martens Marty H. J. , Velders Dick D. , Fijneman Peter , Van Kerkhoven Marco , Noordhoek Jan , Bos Rob P.
Published: February 2007

The use of 1‐nitropyrene (1‐NP) as a marker for the occupational exposure to diesel exhaust (DE) mutagens was investigated in workplace atmospheres contaminated with DE from a variety of emission sources, such as power supplies, forklifts, trucks, caterpillar vehicles, trains, ships' engines, and vehicles in city traffic. Total suspended particulate matter was collected by area sampling. The 1‐NP content of acetone extracts of these samples as determined by gas chromatography‐high resolution mass spectrometry varied from 0.080 to 17 μg/g acetone extractable matter, corresponding to air concentrations of 0.012 to 1.2 ng/m3. A sample collected in a rural area contained 0.0017 ng/m3 1‐NP. The mutagenicity of the extracts was tested in the Salmonella typhimurium strains TA98 and TA1538, using the microsuspension assay with and without metabolic activation by an exogeneous metabolizing system (rat liver S9‐fraction). In addition, the S. typhimurium strains YG1021 and YG1024 were used because of their high sensitivity towards the mutagenicity of nitro polycyclic aromatic hydrocarbons. When plotting the mutagenic potency of the air sample extracts as determined in the absence of liver S9 versus the particle‐associated 1‐NP level, a relatively high correlation (r = 0.80–0.91) was observed in all of the S. typhimurium strains. High correlations (r = 0.80–0.93) were also observed when plotting the results of mutagenicity testing after activation by S9 versus the outcome of chemical analysis. These results show that the 1‐NP content of workplace air samples is associated with their mutagenic potency, suggesting that 1‐NP may be used as a marker for occupational exposure to DE‐de‐rived particle‐associated mutagens © 1995 Wiley‐Liss, Inc.
Study design and sample sizes for a lacl transgenic mouse mutation assay
Authors: Piegorsch Walter W. , Margolin Barry H. , Shelby Michael D. , Johnson Amy , French John E. , Tennant Raymond W. , Tindall Kenneth R.
Published: February 2007

Design features that adjust and account for excess variation in a transgenic mouse mutation assay based on a lacl target transgene from E. coli are considered. These features include proper identification of plate, packaging reaction, and animal identifier codes throughout the experimental and analysis phases of the study, “blocking” of exposed and unexposed animals when preparing and plating multiple packaging reactions from the same genomic DNA sample, separating sectored mutant plaques and complete mutant plaques before performing any quantitative analyses, and testing for sources of excess variation attributable to features of the experimental protocol—such as plate‐to‐plate (within packaging reactions), packaging reaction‐to‐packaging reaction (within animals), and animal‐to‐animal (within study). Control and ethylnitrosourea‐treated animal data are presented from a fully designed study in the lacl assay. The study design incorporates many of these experimental principles. Statistical methods to identify excess variability are noted, and the designed study data are used to illustrate the types of variability encountered in practice. A standard statistical test for two‐sample testing is highlighted, from which recommendations are made for sample size selection in future studies. © 1995 Wiley‐Liss, Inc.
Relative sensitivity of the endogenous hprt gene and lacl transgene in ENU‐treated big blue™ B6C3F1 mice
Authors: Skopek Thomas R. , Kort Kristy L. , Marino Deborah R.
Published: February 2007

Three‐week‐old Big Blue™ (BB) B6C3F1 mice were given a single i.p. injection of ENU. Three weeks later, splenic T cells were isolated from each animal by ficoll gradient centrifugation and divided into two samples. One sample was cultured to measure hprt− mutation and the other was used to extract DMA for lacl− analysis. T cells from BB mice exposed to 0, 4.5, 13.5, and 40 mg ENU/kg (9 or 10 animals per group) displayed dose‐related increases in the frequency of both hprt− and lacl− mutations. Within each treatment group, the ENU‐induced mutation frequency (average observed mutation frequency minus average control frequency) was remarkably similar at the two loci. This suggests that treatments that increase mutation frequency at the endogenous hprt gene also produce similar incremental increases at the BB lacl transgene. However, because of the ten‐fold higher spontaneous mutation rate at lacl, the fold‐increase over background produced by ENU at this locus was significantly less than the fold‐increase produced at hprt. For example, the 4.5 mg ENU/kg treatment produced a 5.2‐fold increase above background at hprt (P = 0.001), whereas only a 1.5‐fold increase was produced at lacl (P = 0.140). Consequently, mutagenic insults that produce up to a fivefold increase in mutation frequency at an endogenous locus may be difficult to detect at the lacl transgene. Finally, the ENU‐induced response at hprt in BB mice was identical to that in generic B6C3F1 mice, suggesting that there are no inherent differences between transgenic and normal mice in their response to this mutagenic agent. © 1995 Wiley‐Liss, Inc.
Improved sensitivity of the unscheduled DNA synthesis assay in primary rat hepatocytes following culture in serum‐free defined media
Authors: Parton Joseph W. , Yount David J. , Garriott Michael L.
Published: February 2007

The unscheduled DNA synthesis (UDS) assay has been used extensively for the in vitro detection of DNA damage caused by compound exposure. However, the in vitro UDS assay has been insensitive for the detection of certain chemicals, particularly nitroaromatic compounds, that are positive in bacterial mutation assays. Recently, studies have been reported which describe alterations in the he‐patocyte membrane following collagenase perfusion. Independently, a method for serum‐free tissue culture has been developed which results in the up‐regulation of cell surface receptors and which may restore membrane functions. Fourteen compounds, including seven nitroaromatics, were evaluated in the in vitro UDS assay employing a serum‐free procedure. Five compounds that were previously reported positive in the standard in vitro UDS assay were also found positive using the serum‐free method. In addition, five of the nitroaromatic compounds produced positive results with the serum‐free method. 1‐Methyl‐3‐nitro‐1‐nitrosoguanidine and 2‐acetylaminofluorene, routinely used as positive controls in the UDS assay, showed greater activity in the serum‐free assay. These results suggest that the use of serum‐free media improves the sensitivity of the in vitro UDS assay and that the serum‐free procedure potentially offers an effective alternative to the more labor intensive and more costly in vivo UDS assay. © 1995 Wiley‐Liss, Inc.
Sensitivity of somatic mutations in human umbilical cord blood to maternal environments
Authors: Manchester David K. , Nicklas Janice A. , O'Neill J. Patrick , Lippert Malcolm J. , Grant Stephen G. , Langlois Richard G. , Moore Dan H. , Jensen Ronald H. , Albertini Richard J. , Bigbee William L.
Published: February 2007

To assess the potential effect of maternal environments on human embryonic/fetal somatic mutation, we measured the frequencies of hypoxanthine‐guanine phosphoribosyltransferase (HPRT, hprt gene), mutant T lymphocytes (Mf), and glycophorin A (GPA) variant erythrocytes (Vf) of both allele‐loss (ø/N) and allele‐loss‐and‐duplication (N/N) phenotypes in umbilical cord blood. The mean hprt Mf (1.40 ± 1.11 × 10−6, N = 66) and GPA Vf (ø/N 4.0 ± 2.2 × 10−6, N = 114; N/N 2.7 ± 2.0 × 10−6, N = 91) were significantly lower than those previously reported for adult populations. In addition, the hprt Mf was significantly higher than that of a published study of newborn cord blood samples from a geographically distant population (0.64 ± 0.41 × 10−6, N = 45, P < 0.01; t test, P < 0.01, Mann‐Whitney U test). An examination of the demographic data from these two populations led to the sampling of 10 additional newborns specifically matched to the published study for maternal socioeconomic status. The hprt Mf (0.70 ± 0.49 × 10−6) of this selected population was consistent with the published report and significantly lower than that of our initial population (P < 0.03, t test; P < 0.01, Mann‐Whitney U test). These results indicate that there is an environmental effect related to maternal socioeconomic status on the frequency of embryonic/fetal somatic mutations. Molecular analyses of hprt mutants from this cohort with elevated Mf revealed a significant decrease in the relative contribution of gross structural mutations to the overall Mf (25 of 38, 66% vs. 34 of 41, 83%, P = 0.024, x2 test), suggesting that the higher Mf resulted from an elevated level of “point” mutations. No individual maternal demographic or environmental factor was identified as contributing more significantly than other any factor to the observed variability in hprt Mf or GPA Vf. © 1995 Wiley‐Liss, Inc.
Analysis of in vivo mutation induced by N‐ethyl‐N‐nitrosourea in the hprt gene of rat lymphocytes
Authors: Mittelstaedt Roberta A. , Smith Beverly A. , Heflich Robert H.
Published: February 2007

The rat lymphocyte hprt assay measures in vivo mutagenicity by quantifying the frequency of 6‐thioguanine‐resistant (TG') spleen lymphocytes cultured in vitro. In this study we have examined the types of mutations induced in the hprt gene of TG' lymphocyte clones from female Fischer 344 rats exposed to 100 mg/kg N‐ethyl‐N‐nitrosourea (ENU). Hprt exons 3 and 8 were amplified from DNA extracted from each of 249 clones, and the resulting products were screened for mutant:wild‐type heteroduplex formation by denaturing gradient gel electrophoresis. The analysis revealed 59 clones with mutations in exon 3, and 20 clones with mutations in exon 8. DNA sequence analysis of the heteroduplexes identified 84 mutations: all of the mutations were base pair substitutions, and 88% were mutations of A:T base pairs. At least 82% were induced independently. These results suggest that the mutations found in TG' rat lymphocytes from ENU‐treated rats were due mainly to ethylthymidine adducts. In addition, a comparison of these results with previously reported in vivo ENU mutational profiles indicates that the types of mutation detected by heteroduplex screening of rat hprt exons 3 and 8 are representative of mutation in the entire protein coding sequence. © 1995 Wiley‐Liss, Inc.

This article is a US Government work and, as such, i s in the public domain in the United States of America.
Induction of micronuclei in human sperm‐hamster egg hybrids at the two‐cell stage after in vitro gamma‐irradiation of human spermatozoa
Authors: Tusell L. , Alvarez R. , Caballin M. R. , Genescà A. , Miró R. , Ribas M. , Egozcue J.
Published: February 2007

The efficiency of the micronucleus test to assess radiation‐induced chromosomal damage in human spermatozoa has been investigated. Micronuclei were scored in human sperm‐hamster egg hybrids at the two‐cell stage, after exposure of human spermatozoa to in vitro gamma‐rays at doses of 0.00, 0.10, 0.25, 0.50, 1.00, 2.00, and 4.00 Gy. The relationship between the yield of micronuclei per two‐cell stage as well as the percentage of two‐cell stages with micronuclei and the different doses of irradiation were fitted to linear equations. To evaluate whether scoring micronuclei is useful for the quantification of chromosomal damage occurring in human spermatozoa, induced micronuclei at the different doses of sperm irradiation were compared to the induction of breaks and fragments in sperm‐derived chromosomes. After interspecific fertilization of zona‐free hamster oocytes by irradiated spermatozoa, a total of 699 fertilized eggs at the two‐cell stage and a total of 387 sperm‐derived complements were analyzed. The incidence of fertilized eggs with micronuclei at the two‐cell stage coincided well with the incidence of sperm‐derived chromosome breaks and fragments (e.g., 8.9% vs. 6.7% in the 0.25 Gy group and 52.8% vs. 58.6% in the 4.00 Gy group). A similar correlation was found between the number of micronuclei per two‐cell stage and the number of breaks and fragments per sperm complement (0.09 vs. 0.07 in the 0.25 Gy group and 0.71 vs. 0.81 in the 4.00 Gy group). The results show that this test system can be used for the quantification of spontaneous or induced chromosomal damage in human spermatozoa. © 1995 Wiley‐Liss, Inc.
Genotoxicity of the natural cercaricides “sucupira” oil and eremanthine in mammalian cells in vitro and in vivo
Authors: Dias Francisca Da Luz , Takahashi Catarina Satie , Sakamoto‐Hojo Elza Tiemi , Vichnewski Walter , Sarti Silvio Jose
Published: February 2007

“Sucupira” oil and the lactone eremanthine, extracted from Pterodon pubescens and Eremanthus elaeagnus, respectively, are known for their cercaricidal action in experimental animals. Because of their biological effect, they have the potential to be used for the prophylaxis of schistosomiasis caused by Schistosoma mansoni. To test the clastogenicity of these agents, “sucupira” oil, either pure or diluted in corn oil, was tested in vivo on Wistar rat bone marrow cells following dermal application. Metaphase analysis showed that the compound did not induce a significant increase in the frequencies of chromosomal aberrations. When eremanthine was tested on BALB/c mice following gavage at doses of 100, 200, and 300 mg/kg bw, it did not induce structural or numerical chromosomal aberrations. In the in vitro treatment of human lymphocyte cultures, eremanthine also did not cause any increase in chromosomal aberrations or sister chromatid exchanges at the following concentrations in culture medium: 1.25, 2.50, and 5.00 μg/ml. From these results, under our experimental conditions, neither “sucupira” oil nor eremanthine showed clastogenic effects on mammalian cells in vivo or in vitro. © 1995 Wiley‐Liss, Inc.
A study of copper recovery from copper‐contaminated sludge with ferrite and selective leaching processes
Authors: Hu S.H. , Wu J.Y. , Hsiao T.C. , Yen F.S. , Tsai M.S.
Published: February 2007

The purpose of this study was to develop an effective resource recovery and leached residue stabilization process for copper‐contaminated sludge. To this end, a treatment procedure utilizing ferrite and selective leaching processes was developed. The XRD examination of ferrite complex revealed the crystalline phases to be mainly Fe3O4, CuO, and 6CuO·Cu2O.

A selective leaching process was followed to recover the copper content of the ferrite complex. To promote the dissolution percentage of copper and repress that of iron, additional 0.5 N sulfuric acid was added at intervals to the suspension in the second step of the selective leaching process. The purpose of this operation was to return the suspension pH back to 3 to promote the dissolution of copper oxide and repress the dissolution of iron.

Finally, the heavy metal (i.e., Cu, Pb, Cr, and Cd) dissolution of the above residue was examined with toxicity characteristic leaching procedure (TCLP) testing and all met the regulatory standard. © 2007 American Institute of Chemical Engineers Environ Prog 26:104–112, 2007
Explicit formulations for evaluation of velocity gradients using boundary‐domain integral equations in 2D and 3D viscous flows
Authors: Gao Xiao‐Wei
Published: February 2007

In this paper, explicit boundary‐domain integral equations for evaluating velocity gradients are derived from the basic velocity integral equations. A free term is produced in the new strongly singular integral equation, which is not included in recent formulations using the complex variable differentiation method (CVDM) to compute velocity gradients (Int. J. Numer. Meth. Fluids 2004; 45:463–484; Int. J. Numer. Meth. Fluids 2005; 47:19–43). The strongly singular domain integrals involved in the new integral equations are accurately evaluated using the radial integration method (RIM). Considerable computational time for evaluating integrals of velocity gradients can be saved by using present formulation than using CVDM. The formulation derived in this paper together with those presented in reference (Int. J. Numer. Meth. Fluids 2004; 45:463–484) for 2D and in (Int. J. Numer. Meth. Fluids 2005; 47:19–43) for 3D problems constitutes a complete boundary‐domain integral equation system for solving full Navier–Stokes equations using primitive variables. Three numerical examples for steady incompressible viscous flow are given to validate the derived formulations. Copyright © 2007 John Wiley & Sons, Ltd.