bluuebunny/crossref_metadata_2025 huggingface dataset:
Maternal toxicity in humans and animals: Effects on fetal development and criteria for detection
Authors: Khera K. S.
Published: February 2006

Evaluation of published human and animal teratology data revealed associations between maternal toxicity and congenital malformations and embryofetal death. This has been reported elsewhere in detail and is herein summarized. Regarding human data, intrauterine deaths were observed to occur in association with (1) maternal homeostatic changes due to phenylketonuria and diabetes and (2) maternal toxicity resulting from alcohol abuse, use of aminopterin, and, possibly, trimethadione. A pattern of malformations that was similar and thus suggestive of a common cause was noticed among malformations attributed to phenylketonuria, diabetes mellitus, aminopterin, alcohol, warfarin, phenytoin, phenobarbital, trimethadione, and valproic acid. On reviewing 234 studies of agents tested in hamsters, mice, rats and rabbits, a fairly strong association between maternal toxicity and embryo‐fetal mortality was observed. Further, a consistent pattern of fetal malformations associated with maternotoxic effects was discovered in a survey of 476 studies of agents tested in these four species. In these reviews, it was postulated that maternal toxicity per se could possibly cause such fetal effects. For evaluating maternotoxic effects in experimental studies, the minimum maternal data required would be frequent measurements of maternal body weight and food consumption, signs of altered behavior, death, and gross lesions at necropsy.
Effect of prenatal reserpine exposure on development of the postnatal rat heart
Authors: Harmon James R. , Kimmel Gary L. , Webb Peggy J. , Delongchamp Robert R.
Published: February 2006

Previous studies have suggested that reserpine treatment may result in altered heart development. In order to more fully investigate this possibility, reserpine was administered s.c. at 0,0.375, or 0.75 mg/kg/day to pregnant rats on gestation days 12–15. Maternal weight gain, as well as pup weight on postnatal day (PND) 1, was significantly reduced in a dose‐dependent manner. Litter size was unaffected, but reserpine‐treated dams had more dead pups than did control dams. On PND 1, litters were randomly standardized at ten pups each for analysis on PNDs 5, 8, 15, and 22. Pup body weight and heart weight were reduced in a doserelated manner at all ages measured. The decreased heart weights were probably due to decreases in cell number. Beta‐adrenergic receptor concentration was significantly reduced only on PND 5, at the low reserpine dose, and was not considered to be a treatment effect. Prenatal reserpine exposure had no effect on levels of basal cardiac ornithine decarboxylase (ODC), an enzyme associated with growth and development. Cardiac ODC stimulation by insulin and isoproterenol also showed no effects of maternal reserpine treatment. The results suggest that maternal reserpine treatment may lead to adverse effects in the developing offspring.
Müllerian remnants of male mice exposed prenatally to diethylstilbestrol
Authors: Newbold Retha R. , Bullock Bill C. , McLachlan John A.
Published: February 2006

Prenatal exposure of males to diethylstilbestrol (DES) results in reproductive tract teratogenesis, ie, retention of Müllerian duct remnants. The potential of these remnants to develop pathological changes has not been studied. Therefore, pregnant outbred CD‐1 mice were subcutaneously injected with daily doses of DES (100 μg/kg) on days 9 through 16 of gestation. DES‐exposed male offspring and age‐matched control male mice were sacrificed at 10 to 18 mo of age and examined for reproductive tract abnormalities. Prominent Müllerian remnants were observed in 268 out of 277 (97%) of the DES‐exposed male mice. These remnants differentiated into “femalelike structures” homologous to oviduct and uterus. The Müllerian remnants were often enlarged and cystic and shared supporting connective tissue with adjacent male structures. Previously reported lesions, termed “epididymal cysts,” were determined histologically to be cystic “oviductlike” structures and were, therefore, considered a Müllerian duct abnormality. Pathological changes in these male oviductal and uterine homologs included benign and malignant lesions.

In addition, epididymal structures were altered. Inflammation and sperm granulomas were prevalent in DES‐treated mice as young as 10 mo old but were only observed in control mice at 18 mos. Cysts of epididymal duct origin, hyperplasia, and adenoma of the epididymal duct were also observed. No comparable abnormalities were noted in 122 control males of corresponding ages.

The data presented in this report demonstrated that transplacental exposure to DES affected the differentiation and normal development of the male genital tract involving both the Müllerian (paramesonephric) and Wolffian (mesonephric) ducts. The long‐term changes in these tissues include lesions, some of which resembled neoplasia although the natural history of the lesions is not known. Moreover, some previously described abnormalities referred to as “epididymal cysts” were associated with tissues derived from embryonic female origin.
Investigation of the teratogenic effects of exercise on pregnancy outcome in mice
Authors: Boehnke William H. , Chernoff Gerald F. , Finnell Richard H.
Published: February 2006

Swiss Webster female mice were arbitrarily assigned to a heavily exercised group (HE), a moderately exercised group (ME), or a sedentary group (S). Exercised groups were subjected to a progressive treadmill training routine, 6 days a week (60 min per day) for a total of 9 wk. Following mating after 6 wk of training, treatment groups continued to exercise at preconceptual intensities. Pregnant mice were sacrificed on the 19th day of pregnancy, and the fetuses were recovered. A positive training effect was demonstrated by a significant increase in succinate dehydrogenase activity in the gastrocnemius muscles of exercising dams. The numbers of implants, resorptions, live fetuses, mean fetal weight, and developmental stage were unaffected by the exercise treatment. A detailed fetal examination revealed no significant skeletal or gross tissue abnormalities in any of the experimental groups.
Cyclophosphamide: Interstrain differences in the production of mutagenic metabolites by S9‐fractions from liver and kidney in different mutagenicity test systems in vitro and in the teratogenic response in vivo between CBA and C 57 BL mice
Authors: Winckler K. , Obe G. , Madle S. , Kocher‐Becker U. , Kocher W. , Nau H.
Published: February 2006

The formation of mutagenic compounds from cyclophosphamide (CPA) by S9‐fractions from liver (S9L) or kidney (S9K) of pregnant CBA and C 57 BL mice was investigated, using point mutations in Salmonella typhimurium (TA 1535) and the induction of sister chromatid exchanges (SCE) in human peripheral lymphocytes (HPL) or Chinese hamster ovary (CHO) cells as end points. In addition, the teratological response of CBA and C 57 BL mice to CPA on day 11 of pregnancy was analysed in vivo.

The results are as follows: (1) S9L from CBA mice was more effective than S9L from C 57 BL mice in metabolizing CPA to products inducing mutations in Salmonella and SCEs in HPL and CHO cells. (2) S9L was more effective than S9K from both strains of mice. (3) In vivo pretreatment of mice with a single dose of CPA (20 mg/kg) reduced the in vitro metabolizing capacity of S9L and S9K significantly and led to the disappearance of the interstrain difference. (4) The embryolethal and teratogenic effects of CPA were stronger in C 57 BL than in CBA mice; the types of teratological effects were partially different in the two strains.
Routine teratogenicity test that uses chick embryos in vitro
Authors: Kučera Pavel , Burnand Marie‐Beatrice
Published: February 2006

An in vitro culture of chicken embryo is described: the embryos at the stage of gastrulation are explanted from eggs into transparent silicone chambers where they continue to develop normally under controlled conditions for additional 3 d. This period corresponds to 2‐5 wk of postconceptional age in the human embryo. In both the chick and man, this period is very sensitive to physicochemical perturbations which can lead to surviving malformations.

Six chemical agents were tested with this culture: methotrexate, cadmium chloride, caffeine, phenobarbital, aspirin, and saccharin. Survival scores, growth perturbations, and early signs of anomalies of the nervous, skeletomotor, and cardiovascular systems were analyzed with respect to the used concentrations. The dose‐response curves were obtained with good precision and allowed a discrimination between the teratogenetic and unspecific toxic effects and a comparison of the toxic potency of the six drugs. The evaluation of one drug took, roughly, 3 wk, one technician, and about 150 eggs.

The advantages (simplicity, rapidity, reproducibility, specificity, economy, no suffering, and no use of mature animals) and disadvantages (nonmammalian species, absence of detoxicating organs) of the method are discussed. The method is proposed as a routine teratogenicity and embryotoxicity test which allows primary screening of many compounds and which can thus substantially reduce the ultimate experiments that use pregnant mammalian females.
Analysis of diurnal difference in teratogen (Ara‐C) susceptibility in mouse embryos by a progressive phase‐shift method
Authors: Endo Akira , Sakai Nobuyoshi , Ohwada Kazuo
Published: February 2006

Our objectives were to determine whether the embryotoxic and teratogenic potential of cytosine arabinoside (Ara‐C) differs depending on the time of day. Pregnant CD‐1 (ICR) mice were placed in an environment where the phases of lighting and darkness were reversed by progressive phase‐delay or phase‐advance methods—2 h every day from day of gestation (dg) 2 to dg 7 (or 6). After it was confirmed that these progressive phase‐shifting methods had no effect on embryonic growth and pregnancy outcome, 5 mg/kg body weight (bt) of Ara‐C was injected intraperitoneally into these animals at 1000 or 1600 on dg 11, and the incidence of gross fetal malformations was compared with that in control dams treated similarly but under a regular lighting regimen (0600–1800). In contrast to previous reports on other teratogens, no diurnal difference was observed in fetal susceptibility to the teratogenic potential of Ara‐C. The possible usefulness of the progressive phase‐shifting method in the field of chronoteratology is proposed.
In vitro embryotoxic effects of ethylene glycol in rats
Authors: Grafton Thomas F. , Hansen Deborah K.
Published: February 2006

Rat embryos of the CD strain were treated in a whole embryo culture system with either 30 or 40 μ1 of ethylene glycol (EG) per milliliter of culture medium for the first 8 (0–8 hr) or second 8 (8–16 hr) hr of a 48‐hr culture period. The compound was not embryolethal under these conditions but did alter growth and development. EG at 40 μ1/m1 of culture medium at 8–16 hr decreased morphological score, somite number, crown‐rump and head lengths, as well as DNA and protein contents. The most frequent abnormality induced by the compound was absence of yolk sac circulation; absent hindlimb bud, hypoplastic telencephalon, and lack of development of the otic and optic systems were also seen in EG‐exposed embryos. Since it has been reported that rodent embryos cultured in vitro lack alcohol and aldehyde dehydrogenases that metabolize EG, present results suggest that the parent compound is capable of altering normal embryonic development when administered during a brief period or organogenesis.
Prenatal and postnatal antimony exposure in rats: Effect on vasomotor reactivity development of pups
Authors: Rossi F. , Acampora R. , Vacca C. , Maione S. , Matera M. G. , Servodio R. , Marmo E.
Published: February 2006

Pregnant female rats were exposed to antimony trichloride (0.1 and 1 mg/dl in their drinking water ad libitum) from the first day of pregnancy until weaning (22nd day after delivery). Pups were exposed to antimony trichloride (0.1 and 1 mg/dl in their drinking water ad libitum) from 22nd until 60th day of age. Antimony exposure did not significantly affect maternal and pup systolic arterial blood pressure, length of gestation, and number of newborn per litter. Antimony exposure decreased maternal and pup body weight. No macroscopic teratogenic effects have been observed. Whether or not pups were exposed to antimony trichloride, pressor responses to carotid occlusion and 1‐noradrenaline and hypotensive responses to 1‐isoprenaline and acetylcholine were significantly higher on the 60th than on the 30th day of age. In pups, prenatal and postnatal antimony exposure did not affect pressor response to carotidal occlusion, while it decreased pressor response to 1‐noradrenaline and hypotensive response to 1‐isoprenaline on the 60th day after birth. At last, antimony exposure at higher concentration decreased pup hypotensive response to acetylcholine on the 60th day.
Studies on the ability of hypotonic solutions to induce chromosomal aberrations in V 79 cell
Authors: Nowak C.
Published: February 2006

V 79 hamster cells were exposed to hypotonic culture medium or to hypotonic solutions of ammonium sulfate, sodium chloride, or trishydroxymethylaminomethane. Hypotonic treatment led in all experiments to a clear increase of chromosomal aberrations. Reasons for the aberrations observed may be directly induced DNA damage such as double strand breaks or a release of DNase after lysosomal damage because of the hypotonic treatment. Other reasons involved in the aberration production may be changes of the internal pH or damage of the chromosomal proteins.
Leukemias and blood dyscrasias following exposure to chlordane and heptachlor
Authors: Epstein Samuel S. , Ozonoff David
Published: February 2006

We present 25 new cases of blood dyscrasia, including leukemias, production defects, and thrombocytopenic purpura, generally following home termite treatment with the chlorinated hydrocarbon pesticides chlordane and heptachlor (C/H). These newly reported cases are consistent with 34 previously published case reports associating blood dyscrasias with C/H exposure. Additionally, the newly reported leukemias are consistent with epidemiologic evidence of excess risk of leukemia and other cancers in C/H‐exposed populations and with the carcinogenic action of C/H in animals. The importance of case reports in warning of the association of blood dyscrasias to C/H exposure is emphasized. Until the voluntary halt in production in July 1987, millions of homes in the United States were treated with chlordane and heptachlor for termites even though their agricultural uses were phased out in 1978, largely on the grounds of “imminent hazard” because of carcinogenicity. In view of the recognized myelotoxicity, carcinogenicity, and other chronic toxic effects of these pesticides, a national program for monitoring all homes treated is urgently needed to detect persistent contamination.
Teratogenicity of N‐(4‐hydroxyphenyl) ‐all‐trans‐retinamide in rats and rabbits
Authors: Kenel Michael F. , Krayer John H. , Merz Eileen A. , Fred Pritchard J.
Published: February 2006

N‐(4‐hydroxyphenyl)‐all‐trans‐retinamide (HPR) has potential efficacy in the treatment of dermatologic, arthritic, and neoplastic disorders. The teratogenicity of such a compound is of special concern in light of the known adverse effects of retinoids, in general, on the developing conceptus. In these studies, Sprague‐Dawley rats and New Zealand White rabbits were treated orally from gestation days 6 to 15 and 6 to 18, respectively, with 0, 20, 125, or 800 mg/kg/day of HPR.

In rat fetuses, low incidences of hydrocephaly (mid‐ and high‐dosage groups) were observed. Fetal tissue (ng/g) and maternal plasma (ng/ml) concentrations of HPR, its major metabolite (N‐[4‐methoxyphenyl] retinamide [MPR]) and retinol were determined in separate groups of similarly‐treated rats 3 h following the last dose on gestation day 15. Fetal tissue concentrations of HPR and MPR were approximately one‐half maternal plasma concentrations. A dose related reduction in maternal plasma and fetal tissue concentrations of retinol were also observed.

In mid‐ and high‐dosage rabbit fetuses, a dose‐related increase in the incidence of dome‐shaped head was observed. Subsequent skeletal evaluation revealed delays in skull bone ossification and a widening of the frontal and frontoparietal sutures. Microphthalmia was also observed in two high‐dosage fetuses. A dose‐dependent and statistically significant reduction in maternal plasma retinol levels was observed across all dosage groups.
Prenatal and postnatal thallium exposure in rats: Effect on development of vasomotor reactivity in pups
Authors: Rossi F. , Marrazzo R. , Berrino L. , De Santis D , Lisa M. , Susanna V. , Montanaro C. , Fici F. , Marmo E.
Published: February 2006

Vasomotor reactivity has been evaluated in rats exposed perinatally and postnatally to thallium sulphate (1 mg/dl in their drinking water ad libitum).

Prenatal and postnatal exposure to thallium did not modify the values of the systolic arterial blood pressure on the 30th and 60th day in pups of normotensive and DOCA‐hypertensive rats. The hypertensive responses induced by endosinusal carotid hypotension and by 1‐noradrenaline in pups of normotensive and DOCA‐hypertensive rats, exposed or not exposed to thallium sulphate, were more intensive on the 60th than on the 30th day. Similar effects were observed for the hypotensive responses induced by 1‐isoprenaline and acetylcholine. Prenatal exposure to thallium did not modify hypertensive responses induced by endosinusal carotid hypotension on the 30th and 60th days, but it caused a decrease of hypertensive responses induced by 1‐noradrenaline on the 30th and 60th days and hypotensive responses induced by 1‐isoprenaline and acetylcholine exclusively on the 60th day.

Postnatal exposure to thallium did not modify hypertensive responses induced by endosinusal carotid hypotension and hypotensive responses induced by acetylcholine, but it caused a decrease of hypertensive responses induced by 1‐noradrenaline on the 30th and 60th days in pups of normotensive rats and exclusively on the 60th day in pups of DOCA‐hypertensive rats. Moreover, postnatal exposure to thallium caused a decrease of the hypotensive response induced by 1‐isoprenaline exclusively on the 60th day.

Our findings show that prenatal and postnatal exposure to thallium sulphate modifies the rat's developing vascular autonomic nervous system with a reduction of the α, β‐adrenergic and muscarinic vasomotor reactivity.
Mutagenicity and carcinogenicity studies of homemade “rust‐proof cutting fluid”
Authors: Wang Da , Huang Wei‐Qun , Wang Heng‐Wen
Published: February 2006

A homemade rust‐proof cutting fluid (RPCF) used in China was tested for carcinogenicity by an in vivo chronic experiment and for mutagenicity by the Ames Salmonella microsomal assay. Undiluted and threefold water‐diluted fluid were given as drinking water to groups of young adult Wistar rats for 2 years. The treatment induced 11/40 malignant tumors with 9/40 acinar adenocarcinomas of the pancreas in the high‐dose group. Simultaneous administration of ascorbic acid dissolved in the undiluted fluid at 2 g acid per 1 g sodium nitrite resulted in 1/40 pancreatic carcinoma. The results of the Ames test showed that the technical RPCF was mutagenic to TA100 with or without metabolic activation. It was concluded that the homemade RPCF, which is comprised of sodium nitrite, triethanolamine, and polyethylene glycol, may form direct‐acting mutagen(s) upon storage and form, in vivo, e.g., nitrosamines that caused acinar pancreatic carcinoma in Wistar rats. Simultaneous administration of ascorbic acid is suggested for the protection of workers exposed to the rust‐proof cutting fluid.
Qualitative analysis of chromosomal evolution in a colcemid‐treated chinese hamster population
Authors: Simi S. , Colella C. M. , Mariani T. , Piras A. , Rainaldi G.
Published: February 2006

Colcemid is known to inhibit the spindle formation and to induce polyploidy and chromosomal nondisjunction. Using a V79 Chinese hamster cell line, we have shown that colcemid is able to induce the formation of cells that are numerically diploid but whose karyotype, when analyzed with the G‐banding technique, differs from that of the untreated ones. Even though these cells have a normal chromosomal constitution, they carry alterations in the chromosomal balance and, consequently, in gene dosage. This could result in an abnormal expression of cellular genes or in the expression of new or preexisting recessive mutations, even in a diploid chromosomal constitution.
Dominant lethality in mice—a test for mutagenicity of influenza X‐31 virus
Authors: Pathki Vandana K. , Polasa H.
Published: February 2006

The induction of dominant lethal mutation in germ cells is the cause of embryonic death resulting in the reduction of litter size in the F1 progeny. Dominant lethal mutations were induced when male mice were infected with live A2 influenza virus. The chromosomal aberrations induced in the germ cells were shown to be responsible for the dominant lethality. Killed influenza virus was also potent in inducing chromosomal aberrations in spermatocytes of mice. In light of these observations, the UV‐inactivated virus was tested for its potency in induction of dominant lethality in both female and male germ cells. The virus‐inoculated females were mated with uninjected males and vice versa. Both the inactivated and live virus were found to induce dominant lethality in both female and male mice, indicating that not only the live virus but also the inactivated virus is capable of bringing about chromosomal damage resulting in dominant lethality.
Effects of N‐acetylcysteine on fetal development and on phenytoin teratogenicity in mice
Authors: Wong Mayme , Wells Peter G.
Published: February 2006

The teratogenicity of phenytoin may result from its enzymatic bioactivation to a reactive intermediate, which interacts irreversibly with fetal tissues. Since glutathione (GSH) is involved in the detoxification of many reactive intermediates, N‐acetylcysteine (NAC), a glutathione precursor, was evaluated for its effects on murine fetal development and phenytoin teratogenicity. NAC, 100 to 275 mg/kg, was given intraperitoneally (ip) or per os (po), or as 266 to 410 mg/kg in the drinking water, at various times before or after phenytoin, 65 to 75 mg/kg ip, on gestational days 12 and 13. Dams were killed on gestational day 19, fetal resorptions were noted, and fetuses were examined for anomalies. Significant reductions in phenytoin‐induced fetal weight loss and cleft palates were observed when NAC was given by gavage 6 hours after phenytoin or in the drinking water with the lower dose of phenytoin. NAC administered in the drinking water also reduced the incidence of resorptions produced by the higher dose of phenytoin and enhanced postpartum survival in fetuses exposed to 65 or 75 mg/kg phenytoin (P < .05). Conversely, the incidence of resorptions increased when NAC was given by gavage at other times before or after phenytoin, by single or repetitive ip injections, or in high concentrations in the drinking water (P < .05). When given with the higher dose of phenytoin, NAC administered via the drinking water significantly increased the incidence of phenytoin‐induced cleft palates and fetal weight loss (P < .05). Similar results were obtained with a single ip injection of NAC and a lower dose of phenytoin. Thus, when given orally, NAC can partially reduce phenytoin teratogenicity and embryopathy. However, altering the route of NAC administration, or increasing the dose of phenytoin and/or NAC, enhanced phenytoin embryotoxicity, and NAC alone at higher doses had embryopathic effects.
Effect of smokeless tobacco on the development of the cd‐1 mouse fetus
Authors: Paulson Ruth , Shanfeld Joseph , Sachs Larry , Ismail Mounira , Paulson John
Published: February 2006

The objective of this study was to examine the effect of smokeless tobacco (ST) on the development of the CD‐1 mouse fetus. ST was administered continuously via Alzet osmotic minipumps during the critical gestational days 7–14 and 6–13. Two ST dosages were administered, 3.2 mg/ml (Dosage I) and 6.4 mg/ml (Dosage II), which yielded plasma nicotine levels within the range comparable to those of an average ST user or smoker (36.0 ng/ml).

Plasma nicotine levels were maintained in the range of 29.4 ± 4.8 ng/ml to 44.3 ± 16.0 ng/ml for the Dosage I group of dams, and in the range of 34.6 ± 10.9 ng/ml of 75.5 ± 19.9 ng/ml for the Dosage II group of dams. The main effect on the fetus was weight reduction, with Dosage I producing a tendency toward weight reduction (p = .08). Dosage II produced a significant 8.6% weight reduction from normal (p < .0001) and an increase in fetal deaths (p < .03). Dosage I produced an increase in the incidence of hemorrhages and supernumerary ribs, and a significant delay (p < .05) in ossification of the supraoccipital bone, the sacrococcygeal vertebrae, and the bones of the forefoot and hindfoot. There were no significant differences between placental weights. Weights of dams were significantly reduced only at the higher ST exposure levels.

We conclude that at plasma nicotine levels comparable to those of an average ST user, ST produces weight reduction, delayed ossification, and increase in hemorrhages and fetolethality in the CD‐1 mouse fetus.
Stage‐related induction of chromosomal aberrations and SCE in mouse embryos treated transplacentally during organogenesis with MMC and DMBA
Authors: Müller Lutz
Published: February 2006

During organogenesis, mouse embryos were treated transplacentally with MMC and DMBA. The clastogenic and SCE‐inducing effects of MMC and the clastogenic effects of DMBA were analyzed in metaphases from whole embryo suspensions. Positive effects were observed on all the days of pregnancy on which the embryos were analyzed, i.e., on days 10, 11, 12, and 13. Whereas the MMC‐induced SCE‐frequencies did not change significantly during the tested period, the clastogenic effects of MMC and DMBA varied drastically. Extremely high aberration rates were observed in embryos on day 11; on the other days the aberration rates were much lower. Factors that might have given rise to these stage‐related effects are discussed.
Effect of nitrous oxide on embryonic macromolecular synthesis and purine levels
Authors: Hansen Deborah K. , Grafton Thomas F.
Published: February 2006

Nitrous oxide (N2O), an anesthetic gas, has been implicated as a human teratogen. The mechanism for its developmental toxicant effects is not known but may involve depression of embryonic macromolecular synthesis caused by alterations in precursor concentrations. Such changes might be caused by decreased folate levels. Pregnant rats were exposed to 50% N2O for 24 hours on day 10 of gestation; this is not an anesthetic dose. Embryos were removed immediately after exposure and grown in a rodent whole embryo culture system for 4 hours in medium containing radiolabeled precursors for RNA or protein. Exposure to N2O decreased embryonic DNA and RNA contents but did not alter number of somite pairs or protein content. Such treatment also decreased incorporation of radiolabeled uridine into acid‐precipitable RNA. There was no difference between control and treated embryos in the incorporation of radiolabeled leucine into protein. There were also no differences between control and exposed embryos in the level of acid‐soluble purines. The lower DNA and RNA contents in N2O‐treated embryos are apparently not the result of decreased levels of adenine or guanine.
Comparison of behaviors for detection of heritable mutations
Authors: Ficsor Gyula , Goldner Lee , Panda Brahma B.
Published: February 2006

Groups of five male HA (ICR) mice were injected intraperitoneally with 60, 150, 300, or 600 mg/kg body weight of ethyl methanesulfonate (EMS) or with saline vehicle. Each male was mated to two untreated females at 2 and 5 weeks after treatment. The two successive matings utilized sperm derived from post‐ and premeiotic germ cells, respectively. Progeny were evaluated for litter size, body weight, negative geotactic response, swimming patterns, limb use while swimming, water escape time, and open‐field motor coordination activity. Body weight, geotactic response, limb use, and open‐field behavior test results demonstrated that EMS causes heritable behavior mutations in both post‐ and pre‐meiotic germ cells. Among the tests that showed inherited differences between control and treated groups, the computer‐monitored open‐field behavior test was the most definitive.
Effect of heat shock on the mutagenicity of mutagens and carcinogens in Euglena gracilis
Authors: Chreč Ondrej , Krajčvič Juraj , Ebringer Libor , Polónyi Jozef
Published: February 2006

The effect of heat‐shock treatment (42°C for 15 min) on the ability of four mutagens and carcinogens to induce hereditary bleaching in Euglena gracilis cells was investigated. All four mutagens (treatment time: 1–24 h) tested after heat shock increased the frequency of bleached mutants of Euglena gracilis.
Somatic mutation induced by heliotrine in Drosophila
Authors: Sivlingham R. , Brink N. G.
Published: February 2006

The pyrrolizidine alkaloid heliotrine has been shown to be a powerful mutagen in Drosophila. This report has evaluated the teratogenicity of heliotrine in this organism. The alkaloid was fed to larvae and its teratogenic effects measured in various developmental stages of the insect. The pupal stage is predominantly affected. The main consequences of treatment were failed eclosions at higher alkaloid concentrations (10−4 M), while lower concentrations (10−4 M) permitted the eclosion of adults, but these showed abdominal abnormalities ranging from severe distortions to reduced numbers of tergite bristles. mei‐9 strains of Drosophila were more sensitive to the production of somatic chromosomal changes as well as the teratogenic effects of the alkaloid. These strains also showed reduced numbers of cells in histoblast nests of 6‐hour‐old prepupae. It is suggested that reduced numbers of histoblast cells in prepupae may be a consequence of genetic damage and this in turn leads to the abdominal distortions and reduced bristle numbers observed.
Comparative antimutagenicity of chlorophyllin and five other agents against aflatoxin B1‐induced reversion in Salmonella typhimurium strain TA98
Authors: Whong Wen‐Zong , Stewart John , Brockman Herman E. , Ong Tong‐man
Published: February 2006

Chlorophyllin was studied for its antimutagenic activity against aflatoxin B1 in Salmonella typhimurium strain TA98 using the plate‐incorporation test in the presence of S9 activation. Comparative antimutagenicity between chlorophyllin and certain commonly studied antimutagens (i.e., vitamins A, C, and E, retinoic acid, and β‐carotene) was also examined. A dose‐related inhibition of aflatoxin B1 mutagenicity by chlorophyllin was observed, with the mutagenicity being abolished by 860 nmole chlorophyllin per plate. The inhibitory activity of chlorophyllin occurred only when cells were treated concurrently with chlorophyllin and aflatoxin B1. The antimutagenic potency of chlorophyllin was comparable to that of vitamin A and higher than that of retinoic acid and β‐carotene. Vitamins C and E had no effect on aflatoxin B1 mutagenicity under the conditions used. The results of toxicity tests and a reconstruction experiment showed that inhibition of the mutagenicity of aflatoxin B1 by chlorophyllin and the other active agents was due to antimutagenicity.
Human embryonic cell growth assay for teratogens with or without metabolic activation system using microplate
Authors: Tsuchiya Toshie , Matuoka Atsuko , Sekita Setsuko , Hisano Takuzo , Takahashi Atsushi , Ishidate Motoi
Published: February 2006

In vitro microassay for the screening of teratogens was investigated on cancer chemotherapeutic agents sterigmatocystins and benzimidazoles using human embryonic palatal mesenchymal (HEPM) cells. Five thousand cells were inoculated into each well of 96‐well microtiter plates, and cultivated for 24 hr, after which the media were changed with new ones that contained various amounts of chemicals; after cultivation for an additional 72 hr, the media were discarded, and cells attached to the tissue plate were fixed and stained with Giemsa's solution; the cell number then was counted by colony counter with three readings for each well. For the metabolic activation, the liver S9 obtained from rats pretreated with phenobarbital and 5,6‐benzoflavone and cofactors (S9 mix) were added directly to the HEPM cell cultures along with chemicals. After 6 hr, the cultures were exchanged with a fresh medium and incubated for a further 72 hr. The final IC50 (the concentration that inhibits growth 50%) concentration‐finding run had 7 to 11 concentration points (mean, three to four wells).

Concentrations of the cancer chemotherapeutic agents that inhibited growth by 50% ranged from 0.001 to 10 μg/ml. Sterigmatocystins indicated strong inhibition; among three derivatives, O‐acetyl sterigmatocystin was the most potent inhibitor. Benzimidazoles also exhibited an inhibitoy action on HEPM cell growth; nitro and chloro groups at the 5 position in 2‐(2‐pyridyl)benzimidazole were found to be potent substituents. As for the activation of cyclophosphamide in the HEPM cell culture, IC50 was decreased to 1.0 ug/ml by the incubation with S9 mix for 6 hr under our experimental conditions, and sterigmatocystin was found to be activated by S9 mix. This system was simple and useful for the detection of teratogens that inhibit HEPM cell growth with or without metabolic activation system.
Evaluation of sister chromatid exchange as an indicator of sensitivity to N‐ethyl‐N‐nitrosourea‐induced carcinogenesis in rats
Authors: Aitio A. , Cabral J. R. P. , Camus A.‐M. , Galendo D. , Bartsch H. , Aitio M.‐L. , Norppa H. , Salomaa S. , Sorsa M. , Husgafvel‐Pursiainen K. , Nurminen M.
Published: February 2006

Sister chromatid exchange (SCE) frequencies in peripheral lymphocytes are a frequently used endpoint to indicate exposures to genotoxins in groups of humans. The aim of this study was to ascertain, in an experimental design, whether or not SCE rates have any association with the risk of cancer at the individual level in rats exposed to a known carcinogen. Individual SCE rates were determined in three consecutive analyses in cultured blood lymphocytes of 50 adult male Wistar rats. Analyses were done before as well as 24 hr and 7 days after a single intraperitoneal administration of 0, 25, 50, or 75 mg/kg of N‐ethyl‐N‐nitrosourea (ENU). The animals were followed until death; also, the relationship between SCEs and carcinogenic outcome, i.e., the presence or absence of tumors, and their latency period were examined. ENU significantly decreased the life expectancy of the rats. The tumor types most clearly associated with ENU treatment were various gliomas and thyroid‐gland and testicular tumors. ENU induced a moderate (maximally 1.6‐fold) increase in the mean frequency of SCEs/cell at both sampling times after treatment. The effect was somewhat more pronounced 1 day rather than 1 week after treatment. The mean SCE rates in rats with ENU‐specific cancers or in animals with early or multiple tumors did not differ from those in animals that survived no less than 65 weeks or longer without developing tumors. In ENU‐treated animals with tumors, no relationship was found between the mean SCE rate and survival time. It is concluded that in outbred Wistar rats the SCE response in cultured lymphocytes does not indicate individual susceptibility to the carcinogenic action of ENU. On a group basis, however, animals with high SCE rates were shown to have increased risk of cancer.
Studies of mutagenesis and neoplastic transformation by bivalent metal ions and ionizing radiation
Authors: Little John B. , Frenial Jean‐Michel , Coppey Jacques
Published: February 2006

We examined the influence of nontoxic concentrations of each of two essential (Zn++ and Mn++) and one nonessential (Ni++) bivalent metal ions on spontaneous and radiation‐induced neoplastic transformation and specific gene mutations in mammalian cells. All three metals induced low levels of transformation in mouse BALB/3T3 cells but exerted no mutagenic effect in CHO cells (hprt locus) over a broad range of concentrations. Continuous incubation for 8 or 15 days with each of the metal ions did not enhance the frequency of cell killing, transformation, or mutations induced by acute exposure to x‐rays. Zn++, however, had a small but consistent protective effect on the induction of all three endpoints by xirradiation.
Mutagenicity of topoisomerase‐active agents in bacteriophage T4
Authors: Demarini David M. , Kay Lawrence B.
Published: February 2006

Recently, the antitumor agent 4′‐(9‐acridinylamino)‐methanesulfon‐m‐anisidide (m‐AMSA) was shown to revert a frameshift mutant of T4 (rFCll), and its mutagenicity was shown to be mediated by T4 DNA topoisomerase II [Ripley et al.: J Mol Biol 200: 665–680, 1988]. Here we report dose‐response data on the mutagenicity and toxicity of m‐AMSA in T4 rFCll. We find that m‐AMSA is among the most potent frameshift mutagens observed in T4, inducing a 10‐fold increase in mutant frequency in the absence of toxicity and a 500‐fold increase in mutant frequency at 31% survival. In addition to m‐AMSA, the topoisomeraseactive agents ellipticine, oxolinic acid, and nalidixic acid also reverted rFCll; however, they required concentrations 10–100 times greater than those required by m‐AMSA in order to be mutagenic, and they did not produce mutant frequencies as high as those produced by m‐AMSA. Unlike m‐AMSA, all three agents were mutagenic only at toxic doses. The other agents evaluated—actinomycin D, adriamycin, 9‐aminoellipticine, 9‐methoxyellipticine, teniposide (VM‐26), and novobiocin—were toxic but not mutagenic to T4 rFCll. Thus, m‐AMSA appears to be distinctly different from the other topoisomerase‐active agents in exhibiting such potent mutagenic activity in T4 rFCll. Because E. coli DNA gyrase may substitute for T4 topoisomerase II, we examined the ability of two inhibitors of E. coli DNA gyrase, novobiocin and nalidixic acid, to inhihit m‐AMSA's mutagenicity. Both agents substantially reduced the mutagenicity of m‐AMSA in T4 rFCll, further suggesting that topoisomerase mediates the mutagenicity of m‐AMSA.
Micronucleus induction in mouse and rat fetuses treated transplacentally during histogenesis with mitomycin c and 7,12‐dimethylbenz(a)anthracene
Authors: Müller Lutz
Published: February 2006

During histogenesis, mouse and rat fetuses were treated transplacentally with mitomycin C (MMC) and 7,12‐dimethylbenz(a)anthracene (DMBA). The micronucleus (MN)‐inducing effects of MMC were analysed in mouse fetal blood and liver; the effects of DMBA were analysed in mouse fetal and rat fetal blood and in maternal bone marrow of both species. Both test substances were clearly clastogenic during the period of development in which the embryos were analysed—i.e., MMC from gestational day 14 until day 18 in mice and DMBA on days 14 and 17 in mice and days 16 and 19 in rats. In mouse fetal liver and blood the MMC‐induced MN frequencies did not vary significantly during the whole period. MMC was more effective in fetal blood than in fetal liver. DMBA‐induced MN frequencies in maternal bone marrow were slightly higher in rats than in mice. Compared to maternal bone marrow, fetal MN frequencies were about four to five time higher in rats but less than two times higher in mice. Thus, rat fetuses were far more susceptible to the clastogenic action of DMBA than mouse fetuses. These results are discussed with respect to fetal development and maternal/fetal metabolism.
Evaluation of the developmental toxicity of nicotine and cotinine with frog embryo teratogenesis assay: Xenopus
Authors: Dawson Douglas A. , Fort Douglas J. , Smith Gregory J. , Newell Deborah L. , Bantle John A.
Published: February 2006

The teratogenic potential of nicotine and a primary metabolite, cotinine, was examined with FETAX (Frog Embryo Teratogenesis Assay: Xenopus). Early embryos of Xenopus laevis were exposed for 96 hr to nicotine or cotinine in two separate static renewal tests of each compound without addition of the metabolic activation system (MAS). Two static renewal tests of nicotine with the MAS were also conducted. Addition of the MAS to nicotine reduced the LC50 from an average of 136 to 20 mg/L. However, the EC50 (malformation) was increased from 0.4 to 5.8 mg/L upon activation. The LC50 and EC50 values for cotinine averaged 4,340 and 720 mg/L, respectively. Based on mortality/malformation index values, growth end points, and the types and severity of the induced malformations, nicotine and cotinine scored as potential teratogens. Metabolism of nicotine to more polar metabolites increased the nicotine concentration required to induce terata. The results are indicative of the versatility of FETAX in developmental toxicity testing.
Sister chromatid exchange in human lymphocytes exposed to ascorbic acid and the cancer chemotherapeutic agent 1‐(2‐chloroethyl)‐3‐cyclohexyl‐1‐nitrosourea
Authors: Best Robert G. , McKenzie Wendell H.
Published: February 2006

This study examines sister chromatid exchange (SCE) induction by ascorbate, a weak in vitro SCE inducer which acts through free radical intermediates, and low doses of 1‐(2‐chloroethyl)‐3‐cyclohexyl‐1‐nitrosourea (CCNU), a potent SCE inducer which acts primarily through DNA interstrand cross‐links. A small dose‐dependent increase in SCE was observed in human peripheral lymphocytes exposed to ascorbate in the 0.5–10 mM dose range for 59 hours, with significant slowing of cell cycle kinetics at concentrations at and above 5 mM. CCNU concentration was selected to approximate the maximal increase in SCE induced by ascorbate. SCE frequencies in cells exposed sequentially to both agents were not significantly different from expectations under an additivity‐of‐effect model based on SCE response to each agent individually. Despite clear differences in the types of lesions induced, ascorbate and CCNU appear to act independently to induce SCE in a manner consistent with, though not exclusive to, Painter's replicon cluster model.
Induction of estrogen receptor, peroxidase activity, and epithelial abnormalities in the mouse uterovaginal epithelium after neonatal treatment with diethylstilbestrol
Authors: Andersson Christer , Forsberg John‐Gunnar
Published: February 2006

Neonatal female NMRI mice were treated with daily doses of 10−2 or 5 μg diethylstilbestrol (DES) on one or more of days 1–5 after birth. Using immunohistochemical techniques and a monoclonal antibody to the estrogen receptor, we demonstrated an estrogen‐induced precocious appearance of receptor protein in the nuclei of the uterovaginal epithelium. High levels of peroxidase activity and a pronounced stromal infiltration with peroxidase positive cells occurred in the uterine cervix and upper vagina after estrogen treatment. This regional restriction in peroxidase activity was similar to the regional restriction for estrogen‐induced epithelial abnormalities (heterotopic columnar epithelium, adenosis). A combined treatment with DES and corticosterone depressed peroxidase activity but not to the control level. The distribution of abnormal epithelium was similar in DES‐and DES‐corticosterone‐treated females. The conclusion is that neonatal estrogen treatment induces an epithelial receptor for estrogen and a high level of cervical peroxidase activity, but the relationship between these parameters and the appearance of abnormal cervicovaginal epithelial changes could not be settled in the present study.
Relationship of periventricular overgrowth to hydrocephalus in brains of fetal rats exposed to benomyl
Authors: Ellis William G. , De Roos Francis , Kavlock Robert J. , Zeman Frances J.
Published: February 2006

Benomyl, a benzimidazole fungicide, was administered by gavage to pregnant Sprague‐Dawley rats in a daily dose of 62.5 mg/kg of maternal body weight beginning at gestational day (GD) 7. Fetuses examined histologically at GD16 or GD20 revealed a high incidence of craniocerebral anomalies—82.6% of those examined at GD16 and 100% of those examined at GD20. Hydrocephalus occurred in 65.2% of fetuses examined at GD16 and in 58.8% at GD20 but was more severe in the GD20 fetuses. A second common anomaly, termed periventricular “overgrowth” (PVO), consisted of subependymal cell masses that in some fetuses obliterated normal subcortical structures. PVO occurred in 34.8% of fetuses examined at GD16 and 76.5% at GD20. The size of the subependymal masses and the regions involved were considerably greater in the GD20 than the GD16 fetuses. Less common anomalies in the GD20 fetuses were periventricular necrosis (41.2%), a single fetus with exencephaly and another with porencephaly.

In the majority of malformed fetuses, the severity of hydrocephalus did not parallel the severity of PVO around the lateral and third ventricles. PVO involved tissues surrounding the cerebral aqueduct in 17.4% of GD16 fetuses and 38.2% of GD20 fetuses. This “overgrowth” distorted the cerebral aqueduct in a large number of fetuses with ventriculomegaly, and at GD20 moderate and severe ventriculomegaly was in every instance associated with a narrow or completely occluded cerebral aqueduct. These relationships suggest that PVO in the midbrain may play a role in the production of aqueductal stenosis and hydrocephalus in this experimental model.
Limb defects in gray short‐tailed opossums (Monodelphis domestica) following postnatal injection with ethanol or saline
Authors: Fadem Barbara H. , Tassava Roy A. , Miller Sheldon I. , Congleton Lori A.
Published: February 2006

Because the hindlimbs of marsupials at birth are in an embryonic stage of development, this group can prove useful for studies of limb teratology. In this study, injection of neonatal gray opossums with 2 mg ethanol (ETOH) or saline (SAL) in the right or left hindquarter resulted in defects of the associated limb in 44% of ETOH animals and 16% of SAL animals. Affected SAL animals showed gait abnormalities, foot clubbing, and moderately reduced limb size. Affected ETOH animals showed these abnormalities as well as fused digits, missing digits, and, in one case, a partially missing limb. Thus, while injection itself may have resulted in altered limb development, local infusion of alcohol had a further teratogenic effect on such development.
Sister chromatid exchange in human chromosomes from normal individuals and epileptic patients on combinations of anticonvulsants
Authors: Goyle Shobha , Maurya A. K. , Rout U. K. , Kailash S. , Maheshwari M. C.
Published: February 2006

Sister chromatid exchange (SCE) frequency, a sensitive indicator in mutagenicity testing, and mitotic index (MI) have been studied to observe genotoxic effects in epileptic patients on routine combinations of anticonvulsant therapy. All patients, both male and female and from various age groups, revealed an increased frequency of SCE per metaphase and a low MI (P < 0.001) with respect to controls. A nonsignificant decrease in SCE frequency has been observed with an increase in the age of onset of epilepsy. Although the SCE frequency increased and the MI decreased in some groups with respect to the duration of epilepsy, there was no difference observed in SCE frequency with the duration of therapy.