摘要:

AbstractThe effect of ethylnitrosourea (ENU) on chromosomes of mouse bone marrow cells and transplacentally exposed embryonic liver cells was investigated. Chromosome aberrations were found to be dose‐ and time‐dependent. The maximum damage was seen 6 h after the exposure.Chromosome aberrations were also induced in bone marrow cells and lymphocytes of marmosets (Callithrix jacchus) directly exposed to ENU. Aberrations did not, however, occur in offspring whose mothers were treated with ENU before conception. Furthermore, chronic transplacentally exposed offspring have been analyzed. The frequency of chromosome aberrations was not increased in their lymphocytes and fibroblasts. The elimination of chromosome aberrations during embryogenesis is discus

ISSN:0270-3211    

DOI:10.1002/1520-6866(1990)3:3<219::AID-TCM1770030302>3.0.CO;2-5

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractThe mutagenicity of the environment in the vicinity of a lead smelter was examined for 3 years by studies of changes in the frequencies of male germinal mutations of the waxy‐C system ofZea maysand somatic mutations of the stamen hair system ofTradescantia. A transect was run at 0.3, 1.7, 3.2, 7.4, and 11.4 km predominantly downwind from the smelter. The mutagenic responses vary between years, within a year, and with distance. Mutation frequencies are both directional and nondirectional with distance. Concentrations of Pb, Cd, Cu, and Zn measured in soil samples show directional changes with distance each of the 3 years, and joint monotonicity is observed in some cases between mutation frequency with distance and metal concentrations with distance. Of a total of ten experiments with bothZea maysandTradescantia, eight show significantly higher mutation frequencies at one or more locations close to the smelter than at locations more distant or at other control

ISSN:0270-3211    

DOI:10.1002/1520-6866(1990)3:3<231::AID-TCM1770030303>3.0.CO;2-4

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractThis report concerns the attempt to demonstrate the practicability of using microsomal fractions (rat orDrosophila) for activating proteratogens in aDrosophilain vitro teratogen screening assay. Accordingly, a typical proteratogen (cyclophosphamide) was tested before and after microsomal activation and results compared with the drug directly on the in vitro assay. The effects of microsomal activation on known teratogens (thalidomide) and nonteratogens (acetaminophen) were also assayed in order to determine the specificity of the activation process. The results showed activation of the proteratogen into a teratogen occurred as in comparable systems. Activation was specific as teratogens and nonteratogens were not altered in the assay. These preliminary results represent the first direct demonstration that theDrosophilamicrosomal fraction is capable of bioactivating a proteratogen. This capability further extends the usefulness of theDrosophilaembryonic culture assay as an in vitro screen for potential teratogens.

ISSN:0270-3211    

DOI:10.1002/1520-6866(1990)3:3<255::AID-TCM1770030304>3.0.CO;2-S

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractThe induction of chromosomal damage (sister chromatid exchanges (SCEs), chromosomal aberrations, and micronuclei) in T lymphocytes from mouse spleen was analyzed after treatment in vivo with different concentrations of mitomycin C (MMC). Lymphocytes were derived from BALB/Mo mice, which carry an endogenous type C retrovirus (Moloney murine leukemia virus, M‐MuLV), and from BALB/c mice (controls, M‐MuLV‐free). Chromosomal damage was determined in vitro on lymphocytes stimulated with concanavalin A (Con A) and incubated for two generation cycles with bromodeoxyuridine (BUdR).The baseline frequency of SCEs was significantly higher in untreated BALB/Mo than in BALB/c lymphocytes. The frequencies of SCEs were significantly increased by increasing doses of MMC in both BALB/c and BALB/Mo T lymphocytes. Treatment with a low dose of MMC (0.3 mg/kg) produced an additive effect on SCE frequency in BALB/Mo lymphocytes, which was gradually suppressed by increasing the MMC concentration (3–5 mg/kg). Indeed, the levels of SCEs became significantly lower in BALB/Mo than in BALB/c lymphocytes at the highest MMC concentration tested (10 mg/kg), indicating that a negative synergistic effect was eventually produced.Chromosomal aberrations (breaks and total aberrations) were significantly increased by the highest MMC doses (5–10 mg/kg) and were more frequent in BALB/Mo than in BALB/c lymphocytes at 10 mg/kg MMC. The frequencies of micronuclei were increased by all MMC doses and were significantly higher in BALB/Mo than in BALB/c lymphocytes at 10 mg/kg MMC.These results are referred to interferences of M‐MuLV and MMC with the function of enzymes, such as DNA topoisomerases, involved in the mechanism of SCE

ISSN:0270-3211    

DOI:10.1002/1520-6866(1990)3:3<263::AID-TCM1770030305>3.0.CO;2-O

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractThe induction of sister chromatid exchanges (SCEs) was studied in the peripheral lymphocytes of workers spraying foliage in forestry with phenoxy acid herbicides 2,4‐dichlorophenoxyacetic acid (2,4‐D) and 2‐methyl‐4‐chlorophenoxyacetic acid (MCPA) or their mixtures. In order to follow possible exposure‐related changes in the frequencies of SCEs, three successive blood samples were taken from 50 male sprayers during the spraying season of July‐October, 1981. In addition, 15 control subjects not working with herbicides were included in the study. The actual exposure levels of the exposed subjects were estimated by measuring the concentrations of 2,4‐D and MCPA in the urine of the sprayers.Enough cells for the SCE analysis were obtained from 35 herbicide workers and 15 control subjects. The concentrations of 2,4‐D and MCPA in the urine samples after exposure varied from 0.00 to 10.99 mg/l. No significant differences in the frequencies of SCEs were observed in samples taken before, during, or after the exposure. Furthermore, the means of SCEs in a nonexposed control group of 15 subjects fell in the same range as those of the exposed subjects. A difference in the means of SCEs was observed between nonsmokers and smokers, smokers having significantly higher mean values than nonsmokers. The results of the present study add support to the earlier data indicating that 2,4‐D and MCPA do not act as direct

ISSN:0270-3211    

DOI:10.1002/1520-6866(1990)3:3<269::AID-TCM1770030306>3.0.CO;2-F

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractEmbryos from day 12 pregnant Swiss mice given intraperitoneal injections of nitrogen mustard (HN2) or cyclophosphamide (CP) were evaluated for chromosomal aberrations. Both agents induced dose‐dependent increases in the frequency of cells with aberrations observed in embryos from females treated 6 hr before sacrifice. The highest frequencies of cells with aberrations were observed when females were injected 15 or 18 hr before sacrifice on day 12. A teratogenic dose of HN2(1.0 mg/kg) induced significantly higher frequencies of damaged cells than a teratogenic dose of CP (20 mg/kg). Cytogenetic analysis of rodent embryos from pregnant females exposed to xenobiotic agents may be an effective screening test for evaluation of genetic effects induced by transplacental exposur

ISSN:0270-3211    

DOI:10.1002/1520-6866(1990)3:3<281::AID-TCM1770030307>3.0.CO;2-E

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractThis structure‐activity model of teratogenicity was developed to provide the ability to rank untested compounds by their probability of teratogenicity. The model is based on 430 compounds collected from various sources in the literature and scored from zero to one as to evidence of teratogenicity. A discriminant equation then separates those compounds in the extremes of this distribution. The false positive classification rate based on the compounds in the equation is approximately 8% and the false negative rate approximately 10%. Approximately 22% of the compounds are not classifiable as either teratogens or nonteratogens with this equatio

ISSN:0270-3211    

DOI:10.1002/1520-6866(1990)3:3<289::AID-TCM1770030308>3.0.CO;2-3

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

ISSN:0270-3211    

DOI:10.1002/1520-6866(1990)3:3<311::AID-TCM1770030309>3.0.CO;2-S

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

ISSN:0270-3211    

DOI:10.1002/1520-6866(1990)3:3<::AID-TCM1770030301>3.0.CO;2-6

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY