ISSN:0270-3211    

DOI:10.1002/tcm.1770050102

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe effects of acute alterations in maternal health status upon fetal development were assessed following exposure of pregnant CD‐1 mice on day 8 of gestation to one of ten chemicals at doses calculated to exert either a low or a moderate degree of maternal lethality. The dams were killed on day 18 of gestation, and the fetuses were examined by routine teratological techniques. The chemicals were cacodylic acid, caffeine, deltamethrin, dinoseb, ethylene bisisothiocyanate sulfide (EBIS), endrin, guthion, kepone, sodium salicylate, and toxaphene. Three (cacodylic acid, EBIS, and kepone) produced dose‐related increases in the incidence of dams with completely resorbed litters. Prenatal mortality in litters that contained live fetuses at term was elevated only for one chemical (cacodylic acid). Fetal weight was reduced in three instances (cacodylic acid, endrin, and guthion), while the incidence of terata was markedly elevated for two (cacodylic acid and kepone). For two other chemicals (endrin and sodium salicylate), a low incidence was found of defects that were similar to defects induced by those chemicals in other species. These effects appear to be chemospecific in nature and not the result of some indirect maternal action. Thus, maternal health status, as measured by the incidence of lethality in the treated groups and by the magnitude of maternal weight gain in surviving females, presents no simple explanation for many manifestations of fetal toxicity. However, for seven chemicals (excluding deltamethrin, EBIS, and kepone) an increased incidence of supernumerary ribs was observed. For three of these seven chemicals (caffeine, dinoseb, and toxaphene). supernumerary ribs was the only observed fetal effect. There was a significant linear inverse‐relationship between maternal weight gain during gestation and the incidence of extra ribs in the treated groups compared to their respective controls. Under the experimental conditions of this study, it appears that the incidence of supernumerary ribs increased in response to a nonspecific maternal tox

ISSN:0270-3211    

DOI:10.1002/tcm.1770050103

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

年代:1985

数据来源: WILEY

摘要:

AbstractMutagenicity withSalmonellastrain TA 100 can be determined by an island test in which only an isolated portion of a pour plate is spotted with a sample. The magnitude of the ratio of the numbers of revertant colonies on the treated and untreated parts of the plate reflects the potency of the mutagen. Five of six chemicals tested yielded statistically significant and generally linear dose‐response curves. Minimum detectable mutagenic doses for four compounds calculated from the dose‐response curves showed that the island test generally required less material for detection of mutagenicity than the liquid pre‐incubation procedure. The island method was primarily designed to test the mutagenicity of aqueous extracts of human stool samples. Dose‐responses were obtained for six such samples, and in two samples the amount of material needed for a positive response was significantly less than that required in the liquid pre‐incubati

ISSN:0270-3211    

DOI:10.1002/tcm.1770050104

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe effects of retinoids (vitamin A analogs) and vitamins C and E on the aflatoxin B1(AFB1)‐induced mutagenesis inSalmonella typhimuriumTA‐98 and TA‐100 were investigated. The bioassay was performed under conditions that permitted the effects of vitamins on carcinogen metabolism to be assessed separately from effects on the expression of the mutated bacterial cell.Both retinoic acid and retinol inhibited (up to 50%) AFB1‐induced mutagenesis inS. typhimuriumTA‐98, but only retinol inhibited (up to 75%) mutagenesis in TA‐100. Retinoic acid inhibition of mutagenesis inS. typhimuriumTA‐98 was pronounced over a wide concentration range (i.e., 2 × 10−10to 2 × 10−8M) however, at the higher concentrations (i.e., 2 × 10−8to 2 × 10−6M range) the predominant effect was the inhibition of the metabolism of AFB1to its mutagenic metabolites. Vitamin E was more potent in inhibiting the expression of AFB1‐induced mutagenesis than vitamin C. However, the major inhibitory effects of vitamin E were related to the metabolism of AFB1, whereas vitamin C was inhibitory at both metabolic and the post‐metabolic levels of the AFB1mutagenesis assay.The results of these investigations suggest that vitamins A, C, or E inhibit both AFB1metabolism to its mutagenic metabolites as well as the expression of AFB1‐

ISSN:0270-3211    

DOI:10.1002/tcm.1770050105

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

年代:1985

数据来源: WILEY

摘要:

AbstractEfforts have begun to establish test subjects other than the intact pregnant mammal to serve as models for rapid teratology screens.Artemianauplii transcending instar I to later instars were examined to determine their potential for indicating chemicals as potential developmental hazards and thus prioritizing them for more extensive in vivo testing. Several criteria selected for assessing the system's potential for screening were the ability to: 1) collect homogeneous populations of instar I nauplii; 2) characterize intermediate development by technically simple measurements; and 3) demonstrate development‐related differentials in naupliar vulnerability.Homogeneous populations of nauplii were harvested from a flow‐through hatching and cold storage system. Nauplii accumulated in the system are stored at 4°C in a quiescent state with little physical (body length, body water volume) and biochemical (DNA and protein levels) change and thus are maintained at instar I. Intermediate development of nauplii transcending instar I to IV was characterized after the onset of 25°C incubation by measuring changes in drinking activity, body length, body water volume, and DNA and protein levels. During the first day of incubation, development was greatest between 6 and 24 hours of incubation.Development‐related differentials in naupliar vulnerability were shown by comparing median lethal concentrations (LC50) estimated for cadmium sulfate (CdSO4), mercuric chloride (HgCl2), and sodium azide (NaN3) at various times during incubation. With cadmium and mercury, LC50s decreased as nauplii aged and developed; whereas, with azide, LC50s did not vary. Developing nauplii were differentially vulnerable to cadmium and inorganic mercury.Artemianauplii transcending instar I to IV appear useful for indicating chemicals that preferentially interact with developmental

ISSN:0270-3211    

DOI:10.1002/tcm.1770050106

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

年代:1985

数据来源: WILEY

摘要:

AbstractPyrimethamine injected into the rat on days 12, 13, and 14 of gestation induces several types of malformations, including limb and facial deformities. These malformations appear in the same location as the hemorrhages and hematomas induced by this substance. In order to visualize the extent of the vascular disorders in the affected areas, a polymerizable substance was injected intravenously into the fetus. After pyrimethamine treatment, the fetal vascular network was simplified and reorganized in a different way according to the severity of the malformations. The appearance of vascular pathology, followed by malformations in the same regions, raises the hypothesis of a vascular cause of fetal defects.

ISSN:0270-3211    

DOI:10.1002/tcm.1770050107

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

年代:1985

数据来源: WILEY

摘要:

AbstractTo determine the effect of artificially produced light on the direct mutagenicity of 2‐aminofluorene, that arylamine was irradiated with either sun, cool‐white, black, blue, or yellow fluorescent light or held in the dark prior to assaying for mutagenicity usingSalmonella typhimuriumstrain TA98. The effectiveness of these exposures in potentiating the mutagenicity of 2‐aminofluorene was sun>black>cool‐white 〉 blue 〉 yellow ≃ dark. By varying the radiant flux densities produced by the lamps and using optical filters, wavelengths of light up to approximately 450 nm were found to be effective in the mutagenic potentiation. Studies using radical scavengers and oxygen modifiers indicated that the light‐induced mutagenicity was dependent on oxygen and that singlet oxygen may be an effective activator of 2‐aminofluorene. The mutagenicity of fluorene was not increased by exposure to light, while only sunlight potentiated the mutagenicity of 2‐acetylaminofluorene. This result suggested the importance of the primary amine in the mutagenic activation of 2‐aminofluorene by light. Light‐activated 2‐aminofluorene was less mutagenic in strains TA98NR and TA98/1,8‐DNP6than in TA98. This observation, combined with the dependence of the photoactivation on oxygen and amino‐substitution, indicated that the light‐enhanced mutagenicity was at least partially due toN‐oxidized photoproducts. These studies indicate that the effect of light on environmental contaminants must be considered in as

ISSN:0270-3211    

DOI:10.1002/tcm.1770050108

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

年代:1985

数据来源: WILEY

ISSN:0270-3211    

DOI:10.1002/tcm.1770050101

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

年代:1985

数据来源: WILEY