bluuebunny/crossref_metadata_2025 huggingface dataset:
Role of maternal plasma corticosterone elevation in the teratogenicity of secalonic acid D in mice
Authors: Eldeib Mohamad M. R. , Reddy C. S.
Published: June 2005

Secalonic acid D (SAD) is a teratogenic mycotoxin that causes cleft palate in the offspring of treated pregnant mice. To investigate the role of maternal corticosterone in the teratogenicity of SAD, pregnant CD‐1 mice were treated with 30 mg/kg of SAD i.p. on day 11 of pregnancy in either 5% (w/v) NaHCO3 or 20% (v/v) dimethyl sulfoxide (DMSO) in NaHCO3. Radioimmunoassay (RIA) was performed to determine plasma corticosterone at 24, 48, 72, and 96 hr after dosing. No interference by EDTA, SAD, DMSO, or pentobarbital was noticed on the RIA. Significant (P < .01) elevations in plasma corticosterone concentrations were seen 24 and 48 hr following dosing of SAD in NaHCO3 with concentrations reaching a peak just prior to the onset of shelf elevation and fusion. Simultaneous treatment with DMSO, an agent known to antagonize the teratogenic effect of SAD, completely abolished the SAD‐induced corticosterone elevation at the 24 hr time point and significantly (P < .01) reduced it at the 48 hr time point. To evaluate the specificity of the role of corticosterone in the teratogenicity of SAD, plasma samples from mature males similarly treated with either single or multiple doses of SAD ranging from 15 to 45 mg/kg were assayed for corticosterone. A dose of SAD comparable to that used in the pregnant females failed to significantly change plasma corticosterone concentrations in the males. An elevation corresponding only to 75% of that in the females was seen in males receiving multiple doses of SAD totaling three times the dose used in the females. As with females, DMSO completely abolished plasma corticosterone elevation by SAD in the males. These results demonstrate, for the first time, the effect of SAD on a mammalian endocrine system and provide evidence for a specific involvement of elevated maternal plasma corticosterone concentrations in SAD teratogenicity.
Effect of lithium carbonate on mouse and rat embryos in vitro
Authors: Hansen Deborah K. , Walker Rhonda C. , Grafton Thomas F.
Published: June 2005

Lithium is effective in the treatment of manic‐depressive psychosis but is suspected to be a developmental toxicant in humans. It is a developmental toxicant in mice and rats in vivo, but at human therapeutic serum levels of 0.6–1.6 meq/L, rats appear to be more sensitive to the effects of the drug than do mice. The species susceptibility to lithium‐induced defects was evaluated by using a rodent whole embryo culture system employing mouse and rat embryos treated at comparable developmental stages. Mouse embryos were cultured on gestational days 8–10, and rat embryos were cultured on gestational days 10–12. Care was taken to insure that all embryos had 10 ± 2 somite pairs at the beginning of the culture period. Embryos were cultured for 44 hours in rat serum to which lithium was added to attain final drug concentrations of 0.6, 1.2, 1.8, 2.4, or 5.0 meq/L. Control embryos were treated with distilled water, which served as the vehicle. In rats, lithium induced significant decreases in various parameters at 1.8, 2.4, and 5.0 meq/L; no malformations were observed in rats of this stage. In mice, significant decreases occurred at 2.4 and 5.0 meq/L, and embryos treated at the highest concentration had a significantly increased frequency of open neural tubes. Rat embryos were also cultured with lithium on gestational days 9–11. The lowest dose producing developmental toxicity at this stage was 0.6 meq/L. Open neural tubes were present among younger rat embryos; however, this defect occurred in all groups, including the control group. These results suggest that there are differences in the susceptibility of mouse and rat embryos at the same developmental stage to the embryotoxic effects of lithium and that there are differences in susceptibility in rats of various developmental stages.
Incidence of anencephaly in Jamaica
Authors: Coard K. , Escoffery C. , Golding J. , Ashley D.
Published: June 2005

Information was collected on 2,197 stillbirths and neonatal deaths on the island of Jamaica during the 12 month period September 1986 to August 1987 as part of the population based nationwide Jamaican Perinatal Morbidity and Mortality Survey. There were 14 cases of anencephalus giving an incidence of 0.26 per 1,000 total births. One of these cases was associated with the amniotic band syndrome; excluding this, the incidence would be even lower (0.24 per 1,000). There was no apparent association with social class, maternal age, or parity. The rate found in Jamaica is considerably lower than found in any other national population study.
Studies of methotrexate‐induced limb dysplasias utilizing a 51chromium release assay
Authors: Brewton Randolph G. , MacCabe Jeffrey A.
Published: June 2005

The folate antagonist methotrexate (MTX), widely used in chemotherapy, is a well‐documented teratogen. However, the mechanism by which it exerts its effects is still unclear. Specifically, we have examined the cytotoxicity of MTX in vivo and in vitro and have looked at the relationship between cytotoxicity and teratogenesis. The chick embryo was utilized to examine the effects of the drug administered to carefully staged embryos. Embryos were exposed at stages 18–22 and examined on day 11 of incubation. Wings were malformed in a stage‐dependent manner while legs were affected similarly at each stage used. A modification of the 51chromium‐release assay was used to test the toxicity of MTX to limb cells in vitro. None of the tissues tested showed measurable toxicity in vitro even though the drug kills cells in vivo, thereby suggesting that MTX may be metabolized differently in vitro. Malformations induced by MTX do not seem to be due to changes in the amount of cell death taking place in the limb but may be caused by a transient inhibition of cell division.
Development, morphology, and function of the yolk‐sac placenta of laboratory rodents
Authors: Jollie William P.
Published: June 2005

A review of current knowledge of the unusual structure and several functions of the yolk‐sac membranes of common laboratory rodents, viz., rats, mice, hamsters, guinea pigs and gerbils, enables a better assessment of the significance of this maternofetal exchange system in the experimental production of congenital anomalies. The anatomy of both visceral and parietal walls of the rodent yolk‐sac placenta—specifically the anatomical relationships of each wall with maternal and with other fetal tissues—depends on the mode of origin and subsequent development of the yolk sac in these several species. Accordingly, the developmental biology of the rodent yolk sac is described. Since both fine structure and anatomical relationships also determine in large measure the functioning of the membrane as a whole in the absorption of selected materials either for intracellular digestion or for cellular translocation and transport to the developing embryo, the anatomy of the yolk sac is considered in detail. Similarly, since available evidence strongly suggests that teratogenic agents induce perturbations in the cellular mechanisms that control these several functions of the yolk‐sac placental system in the production of birth defects, additionally an account is given of the cell biology of the membrane, i.e., endocytosis and targeting/trafficking of materials either for digestion within the epithelium at the maternal surface of the visceral yolk sac or for translocation across the yolk‐sac membrane as a whole.
Cell physiology of the rat visceral yolk sac: A study of pinocytosis and lysosome function
Authors: Lloyd J. B.
Published: June 2005

The rat visceral yolk sac is active in pinocytosis. Macromolecules accumulated by the tissue are, in general, routed to the lysosomes, where they either accumulate (if non‐digestible by the lysosomal enzymes) or are degraded to their monomeric components. The yolk sac cells engage in adsorptive pinocytosis, which leads to the preferential uptake of macromolecules bearing certain surface features, such as a hydrophobic or a cationic domain. Substrates that enter the yolk sac by adsorptive pinocytosis can in some cases act as bivalent ligands, carrying in a second substance by “piggy‐back” pinocytosis. Pinocytosis and intralysosomal digestion of plasma proteins by the organogenesis‐stage rat embryo play an important nutritional role, supplying a high proportion of the embryo's amino acid requirement. Teratogenic effects can be induced by substances that inhibit either pinocytosis or intralysosomal proteolysis at this sensitive stage of gestation.
Experimental manipulation of the rodent visceral yolk sac
Authors: Beckman David A. , Koszalka Thomas R. , Jensen Marcela , Brent Robert L.
Published: June 2005

The visceral yolk sac (VYS) is an especially important placental organ in the rodent because it is the primary source of exchange between the embryo and mother during early organogenesis before the chorioallantoic placenta circulation is established. The VYS is involved with nutritional, endocrine, metabolic, immunologic, secretory, excretory, and hematopoietic functions. The VYS also plays a role in steroid metabolism and interacts with a variety of blood‐borne factors: parathyroid hormone, glucocorticoids, insulin, and vitamin D metabolites. The importance of the VYS during development is emphasized by the embryotoxicity resulting from exposure to agents which cause VYS dysfunction when administered to the pregnant animal during organogenesis. Several experimental procedures have provided useful information concerning a variety of VYS functions from early organogenesis to term: Culture of the Embryo, Fetal Incubation, Culture of the Fetus, Giant Yolk Sac, Short‐ and Long‐Term Culture of the Yolk Sac, Modified Ussing's Chamber, Single or Double Diffusion Chamber, and the use of Heterologous Rodent Visceral Yolk Sac Antibodies. Since human yolk sac pathology has been associated with developmental toxicity and spontaneous abortion, it is important to discover whether there are some common functional roles among different mammalian species and to determine if other experimental animal models can be used to study the possible contribution of human yolk sac dysfunction to some human reproductive problems.
Experimental yolk sac dysfunction as a model for studying nutritional disturbances in the embryo during early organogenesis
Authors: Brent R. L. , Beckman D. A. , Jensen M. , Koszalka T. R.
Published: June 2005

Our investigations concerning the importance of cell surface macromolecules during embryonic development led us to the discovery in 1961 that heterologous anti‐rat kidney serum produced teratogenesis, growth retardation and embryonic death when injected into the pregnant rat during early organogenesis. It was established that IgG was the teratogenic agent, primarily directed against the visceral yolk sac (VYS) but not the embryo. Heterologous anti‐rat VYS serum was prepared which was teratogenic localized in the VYS and served as a model for producing VYS dysfunction and embryonic malnutrition. The role of the yolk sac placenta in histiotrophic nutrition is now recognized to be critical for normal embryonic development during early organogenesis in the rodent. VYS antiserum affects embryonic development primarily by inhibiting endocytosis of proteins by the VYS endoderm, resulting in a reduction in the amino acids supplied to the embryo. Our labratory has recently developed teratogenic monoclonal yolk sac antibodies (MCA) which can be utilized; to study VYS plasma membrane synthesis and recycling, to compare yolk sac function among different species, and to identify components of the plasma membrane involved in pinocytosis. MCA prepared against certain VYS antigens provide an opportunity to study embryonic nutrition with minimal interference with the nutrional state of the mother. Recent developments in the study of the human yolk sac along with our laboratory's ability to isolate a spectrum of yolk sac antigens, prepare monoclonal antibodies, and perform functional studies, should provide information that will increase our understanding of yolk sac function and dysfunction in the human and determine the relative importance of various amino acids to normal devlopment during mamalian organogenesis.
Morphological observations in normal primary palate and cleft lip embryos in the Kyoto collection
Authors: Diewert Virginia M. , Shiota Kohei
Published: June 2005

Normal developmental events during human primary palate formation and alterations associated with cleft lip remain poorly defined. The purpose of this study was to analyze serially sectioned human embryos to identify morphological changes during normal palatal closure and alterations associated with failure of palatal formation. Normal and cleft embryos from the histological collection at the Congenital Anomaly Research Center at the University of Kyoto were studied and photographed for detailed evaluation. Seven serially sectioned cleft lip embryos of stages shortly after primary palate formation (Streeter‐O'Rahilly stages 19, 20, and 22) with unilateral or bilateral clefts with varying degrees of clefting were studied. In the normal Kyoto embryos, initial nasal fin (epithelial seam) formation was observed between the medial nasal process and the lateral nasal and maxillary processes at stage 17. During stages 18 and 19, the nasal fin epithelium was replaced by an enlarging mesenchymal bridge, as the maxillary processes united with the medial nasal processes to form the primary palate. The most prominent features observed in the cleft embryos were a reduced thickness of mesenchymal bridging between the medial nasal and maxillary processes, with an excessive amount of epithelium at the junctions between these processes. With ingrowth of the maxillary processes, greater cell dispersion and apparent extracellular matrix accumulation were observed in the medial nasal region. During closure of the primary palate, terminal branches of the maxillary nerve crossed the mesenchymal bridge to the medial nasal region. The partial clefts had reduced maxillary ingrowth and smaller union areas with the medial nasal process. Detailed studies of experimental animal models are required to identify regional growth required for contact between the facial prominences, to clarify the mechanisms of mesenchymal ingrowth and epithelial displacement during palatal formation, and to identify local and/or general factors causing alterations that lead to primary palatal clefting.
Embryotoxicity of the intercalating agents m‐AMSA and o‐AMSA and the epipodophyllotoxin VP‐16 in postimplantation rat embryos in vitro
Authors: Mirkes Philip E. , Zwelling Leonard A.
Published: June 2005

The intercalating agent, m‐AMSA, and the epipodophyllotoxin, VP‐16, both topoisomerase II—reactive anticancer agents, are also embryotoxic agents in rat embryos cultured in vitro. Quantifying the embryotoxic effects of these drugs revealed that the no observed adverse effect level (NOAEL) for m‐AMSA is 10 nM, the embryotoxic concentration range is 50–500 nM, and complete lethality is observed at 1 μM. In contrast, the NOAEL for o‐AMSA, an inactive isomer of m‐AMSA, is 1.0 μM, the embryotoxic concentration range is 10–100 μM, and complete lethality occurs at 200 μM. Based upon the concentrations of drugs required to produce 50% embryotoxicity or 50% malformed embryos, m‐AMSA exhibits a 200–500‐fold‐higher embryotoxicity compared to o‐AMSA. VP‐16 exhibits a NOAEL of 1.0 μM, an embryotoxic concentration range of 2–5 μM, and complete lethality at 10 μM. Compared to m‐AMSA, VP‐16 is approximately 10‐fold less embryotoxic. At appropriate concentrations, all three drugs were dysmorphogenic resulting in embryos that were characterized by hypoplasia of the prosencephalon with associated microopthalmia and dilation of the rhombencephalon.

As a prelude to future studies focusing on the mechanism of drug‐induced embryotoxicity, we have used established biochemical and immunologic methods to identify and quantify topoisomerase II in rat embryos. In addition, we have demonstrated that the embryo topoisomerase II can be inhibited by both m‐AMSA and VP‐16. Finally, we have used a human cDNA probe to detect topoisomerase II mRNA in the rat embryo. Thus, the combination of the in vitro whole embryo culture and these biochemical/molecular assays should allow us to explore the role of a specific nuclear target, i.e., topoisomerase II, in the teratogenic effects of some commonly employed chemotherapeutic agents.
Marked accumulation of valproic acid in embryonic neuroepithelium of the mouse during early organogenesis
Authors: Dencker Lennart , Nau Heinz , D'argy Roland
Published: June 2005

Valproic acid, an antiepileptic drug, causes neural tube defects in mice and man. 14C‐labeled valproic acid (sodium‐salt) was administered to pregnant mice on days 8 and 9 of gestation (period of high sensitivity in regard to formation of neural tube defects in this species). Two dose levels of valproic acid (1 and 400 mg/kg) were used; in each case the total radioactivity administered was the same: 400 μCi/kg or 14.7 MBq/kg. Autoradiography combined with computerized densitometry revealed that in low‐dose animals most of the radioactivity was confined to maternal liver and kidney, while at high doses more activity was observed in soft tissues and fluids, including amniotic fluid. In the embryo, the neuroepithelium showed the highest concentration, irrespective of dose and survival interval (30 min, 3 h, and 6 h). Upon administration of the high dose, up to five times more radioactivity (approximately 2,000 times more valproic acid) was recovered in embryonic tissues than after the low dose. It is concluded that high doses of VPA saturate the capacities of metabolism, excretion, and protein binding in the maternal organism, resulting in a higher proportion of the dose reaching the embryo, allowing more of the drug to be accumulated by the target organ, the neuroepithelium.
Effects of thyroid antagonists on rat embryos cultured in vitro
Authors: Stanisstreet M. , Herbert L. C. , Pharoah P. O. D.
Published: June 2005

A literature review of individual pregnancies and recent surveys involving large cohorts reveal an association between congenital malformation and maternal hyperthyroidism, suggesting that some aspect of hyperthyroidism or its treatment might compromise the development of the fetus. Experiments have shown that the thyroid antagonist, ethylenethiourea (ETU), causes fetal malformations when administered to pregnant rats, but it is not known whether it is ETU or the imbalance in maternal thyroid hormone which it causes which is the teratogenic agent. Here we employ in vitro culture to determine the possible direct effects on rat embryos of two thyroid antagonists, ETU and methimazole (MMI), the latter being one which is used for treatment of thyrotoxicosis in humans. It was found that ETU can compromise the development of rat embryos in vitro, confirming that ETU has a direct effect on the rat embryo. It was also found that MMI can cause abnormal development of rat embryos in vitro, although the concentration at which MMI disturbs rat embryogenesis is higher than that which is reached in hyperthyroid patients treated with clinical doses of MMI or carbimazole.
Direct embryotoxicity of cocaine in rats: Effects on mitochondrial activity, cardiac function, and growth and development in vitro
Authors: Fantel A. G. , Person R. E. , Burroughs‐Gleim C. J. , Mackler B.
Published: June 2005

Day 10 rat embryos were exposed to cocaine HCl (10–100 μM) in vitro in 20% (designated normoxic) and 10–12% (designated moderately hypoxic) oxygen and examined the following day. In normoxia, it caused prompt and significant decreases in heart rates and significant reductions in measures of growth and development and diameters of the vitelline arteries. In moderate hypoxia, cocaine exposure resulted in axially asymmetric defects reported previously only in embryos exposed to extreme hypoxia or to hypoxia generated by redox cyclers.

Day 10 or 11 embryos or isolated hearts from the latter stage were incubated with cocaine under normoxic conditions. Acute and significant concentration‐dependent decreases in heart rates occurred on day 10. The rates in day 11 embryos and in isolated hearts from day 11 embryos were less sensitive than those on day 10. Cocaine also significantly inhibited the activity of the terminal electron transport system of the mitochondria of embryos.

Maternal cocaine exposure has been associated with uterine vasoconstriction and decreases in fetal oxygenation. The latter has been shown to stimulate glucose uptake. We hypothesize that placental vasoconstriction limits the ability of embryos to meet the increased glucose demands induced by hypoxia. The developmental toxicity of nutrient and oxygen deprivation is further enhanced by significant decreases of mitochondrial activity. We propose therefore that compromised energy supplies form the basis of the developmental toxicity of cocaine.
Developmental effects and mineral interactions in rats fed textured vegetable protein
Authors: Welsh John J. , Rader Jeanne I. , Collins Thomas F. X. , Black Thomas N. , Rorie James I. , Kopral Christine A.
Published: June 2005

The teratogenic effects of feeding a diet based on textured vegetable protein to Long‐Evans rats were studied along with maternal and fetal mineral interactions and their relationship to diet composition. Pregnant rats were fed purified diets containing 18% protein as casein (CAS), textured vegetable protein (TVP, from defatted soy flour) with 18 mg Zn/kg, or TVP diet with 100 mg Zn/kg. A fourth group was fed diet NIH‐31. The animals received their diets throughout pregnancy and were sacrificed on day 20 of gestation. Fetuses were examined for developmental effects, and mineral levels were determined in maternal and fetal tissues by inductively coupled argon plasma–atomic emission spectrometry. Females fed the casein diet or diet NIH‐31 had normal weight gains throughout pregnancy and their progeny exhibited normal development. The animals on the TVP‐containing diet with 18 mg Zn/kg had decreased food consumption and body weights, and their fetuses exhibited developmental anomalies as well as reductions in size and weight. These developmental alterations may be the result of decreased zinc levels in the fetal tissues, caused by reduced bioavailability of the trace element in the maternal diet. Significant increases in tissue iron accompanied the low zinc levels. No developmental effects were found in animals receiving the high Zn‐TVP diet, and mineral data from these animals were not significantly different from the casein group.
Developmental toxicity of orally administered 2′,3′‐dideoxycytidine in mice
Authors: Lindström Pia , Harris Martha , Hoberman Alan M. , Dunnick June K. , Morrissey Richard E.
Published: June 2005

2′,3′‐Dideoxycytidine (DDC), a potent inhibitor of human immunodeficiency virus (HIV), is presently undergoing clinical trials as a promising anti‐AIDS drug. Since there are very limited published animal toxicity data available, and nucleoside analogues are being considered for treatment of HIV‐infected pregnant women, a study was conducted in mice to investigate the potential adverse developmental effects of this drug. DDC, suspended in 0.5% methyl cellulose, was administered via gavage twice per day during gestation days (gd) 6 through 15 to C57Bl/6N mice in a total dose of 0, 200, 400, 1,000, or 2,000 mg/kg/day. Maternal weight gain during the gestation and treatment period, as well as gravid uterine weight, decreased significantly in the 2,000 mg group, but weight gain, corrected for gravid uterine weight, was not affected by DDC. The percent resorptions per litter increased significantly in the highest dose group, and there were fewer live litters because of complete litter resorption in six dams. Among litters with live fetuses, the mean litter size was significantly reduced in the 2,000 mg group. Average fetal body weight per litter decreased significantly in the 1,000 and 2,000 mg groups. The number of fetuses with any malformation, the number of litters with one or more malformed fetuses and the percent of malformed fetuses per litter increased significantly in the 1,000 and 2,000 mg groups. There was an increase in malformations at 400 mg/kg/day; however, it was not statistically significant. In conclusion, DDC produced developmental toxicity (malformations, reduced fetal body weight, and resorptions) in the absence of overt maternal toxicity except for body weight changes due to resorptions and reduced fetal weights.
Delayed neural crest cell emigration from Sp and Spd mouse neural tube explants
Authors: Moase Connie E. , Trasler Daphne G.
Published: June 2005

Splotch (Sp) and splotch‐delayed (Spd) are allelic mutations on chromosome 1 of the mouse. Embryos homozygous for either allele have neural tube defects (NTDs) and deficiencies in neural crest cell (NCC) derived structures. The fact that Spd mouse mutants sometimes have deficiencies in NCC derivatives in the absence of an NTD led to the hypothesis that neurulation and the release of NCCs may depend on a regulatory event that is common to both processes. Therefore, it may be possible to understand the cause of NTDs in these mutants by examining the basis of aberrant NCC derivatives. Caudal neural tubes were excised from day 9 Sp and Spd embryos and placed into gelatin‐coated tissue culture dishes, or 3‐dimensional basement membrane matrigel, and cultured for 72 hours. A cytogenetic marker was used to genotype the embryos. In planar cultures, no morphological differences were observed between NCCs from neural tube explants of Spd mutants compared to those from heterozygous or wild‐type embryos. However, there appeared to be a delay in the release of NCCs from the neural tube in both Sp and Spd mutants, which was particularly evident in Sp. After 24 hours in culture, the extent of NCC outgrowth, as well as the number of NCCs emigrating from explanted neural tubes, was significantly lower in Sp and Spd mutant cultures than in controls. No differences were observed in the mitotic indices among cells which had emigrated. By 72 hours, mutant cultures and their non‐mutant counterparts were similar in terms of outgrowth, cell number, and migratory capability. After 24 hours in 3‐dimensional basement membrane matrigel, cell outgrowth from Sp explants was also significantly less than controls. The pattern of NCC outgrowth in both types of culture conditions indicates a 24 hour delay in mutant cultures compared to controls. This stems from a delay in the release of NCCs from the neural tube, suggesting that the defect lies within the neuroeptihelium with respect to the release of NCCs.
Effect of sample size on reproducibility of behavioral teratological study results: A computer simulation experiment using data from the collaborative behavioral teratology study of the national center for toxicological research
Authors: Tachibana Toshiaki
Published: June 2005

A computer simulation experiment which attempted to examine the effect of sample size on reproducibility of the effect of treatment was performed on the basis of actual data obtained from the Collaborative Behavioral Teratology Study of the National Center for Toxicological Research. The degree of the treatment effect was assessed in terms of the strength of the association (eta square). The results indicate that sample size has a large effect on the reproducibility of results which are assessed with the magnitude of SD for eta squares obtained from replication experiments. Suitable sample sizes to obtain relatively consistent results across studies were discussed, pointing out that not enough attention has been paid to the effect of sample size in the issue of reproducibility of results in some behavioral teratology studies.
Dithiocarbamates and prevention of cadmium teratogenesis in the hamster
Authors: Hatori Akiko , Willhite Calvin C. , Jones Mark M. , Sharma Raghubir P.
Published: June 2005

Certain dithiocarbamates (DTC) have been reported to protect against cadmium (Cd)‐induced lethality and to decrease Cd body burden. The present study evaluated the influence of sodium N‐benzyl‐D‐glucamine dithiocarbamate, sodium N‐di(hydroxyethyl)amine dithiocarbamate, sodium 4‐carboxyamidopiperidine‐N‐dithiocarbamate, and sodium N‐methyl‐D‐glucamine dithiocarbamate on Cd‐induced teratogenesis in the hamster. When given as a single ip injection at 2.2 mmol/kg 15 min prior to iv CdCl2 (2 mg/kg), all of the DTC afforded significant protection against Cd‐induced developmental toxicity and reduced kidney [Cd] in the dam. Maternal liver [Cd] was reduced with the glucamine and dihydroxyethyl amine analogs, but treatment with the piperidine failed to influence hepatic [Cd]. Pretreatment of the dams with DTC 24 hr prior to Cd challenge failed to protect against Cd‐induced embryotoxicity, and provided minimal, if any, reduction in renal or hepatic [Cd]. Pretreatment with the N‐methyl‐D‐glucamine congener 24 hr prior to Cd exposure increased embryolethality. The dose‐time relationships found here suggest that pharmacologically effective levels of these DTC decline within 24 hr of treatment and that induction of metallothionein does not play a major role in DTC antagonism of Cd poisoning.
Triploidy syndrome in a liveborn female
Authors: Schwaibold H. , Dulisch I. , Wittekind Ch. , Voikulescu I. , Kiefer G. , Böhm N.
Published: June 2005

We present the autopsy report of a liveborn triploid female, born after 36 weeks of gestation, who died at the age of 20 hours. External features were diagnostic: fetal hypoplasia, hypertelorism, microstomia, micro and retrognathia, preauricular skin tag, low‐set ears, and 3–4 syndactylia. All internal organs were hypoplastic. There were atrial and ventricular septal defects. Adrenals and kidneys were fused, the gallbladder was absent, and ovarian hilum cell were found to be hyperplastic. Triplolidy, 69xxx, was confirmed cytogenetically. The placenta was hypoplastic and, microscopically, revealed a peculiar type of immaturity, so‐called hydatidiform villous hypoplasia, findings which have not been previously reported. We suggest that the generalized fetal and placental hypoplasia and the severe hypoplasia of all internal organs are caused by a proliferative deficiency of the triploid cells. In addition, the nuclear DNA content was determined cytophotometrically from placental stromal cells and was found to be about 50% above the normal diploid DNA value; i.e., a triploid DNA value was confirmed.
Fallacies of international and national comparisons of disease occurrence in the epidemiology of neural tube defects
Authors: Borman Barry , Cryer Colin
Published: June 2005

Despite extensive research, little progress has been made in elucidating the etiologies of anencephalus and spina bifida. International and national distributions of disease occurrence have often been used as a basis for generating etiological hypotheses (e.g., potato blight, tea consumption, and zinc deficiency hypotheses). However, few of the epidemiological studies of neural tube defects (NTDs) have been conducted with scientific rigor in design, and most are of dubious validity, often with low precision in the estimates. This paper shows that the accepted geographic patterns of NTDs may be attributable to variations in the validity of studies used to describe these patterns. The nonuniformity in the duration and diligence of case ascertainment, the lack of a standardized nomenclature and classification, and the definition of the denominator remain principal problems in evaluating the epidemiology of NTDs. For example, the distinction between incidence and prevalence is not always made, and there is no consistency in the placement of the gestational boundary between late fetal deaths and spontaneous abortions. Findings are compared from studies conducted at different times, without due regard to the effect of secular trends, and using studies that have varying levels of case ascertainment. In etiological research, it is important to perform studies that are accurate and precise, but the literature used to define the spatial distribution of NTDs has often been accepted without due regard to the effect of these factors.
Influence of some methodological factors on the radiosensitivity of the mouse zygote
Authors: Jacquet P. , Grinfeld S.
Published: June 2005

The experiments reported here were undertaken to investigate the influence of some methodological factors on the radiosensitivity of the mouse zygote. The following factors were studied: (1) the use of natural or hormone‐stimulated ovulation; (2) the procedure followed for fertilization:mating overnight, or only during a short period in the morning after all oocytes have been ovulated, in vitro fertilization; (3) the type of irradiation, i.e., in vivo or in vitro irradiation. The radiosensitivity of the zygotes was estimated under the different experimental conditions by measuring the ability of the irradiated embryos to cleave and to develop further to the blastocyst stage. Our results suggest that the protocols used for mating and fertilization probably have a greater influence on embryonic survival following irradiation than the use of gonadotropins to stimulate ovulation. The highest degree of synchrony in the development of the embryos is achieved by restricting mating to a short period or by using in vitro fertilization. The very low LD50s obtained under such synchronous conditions confirm the high radiosensitivity of the mouse zygote at the early pronuclear stage. Comparison between the effects of in vivo and in vitro irradiation does not indicate a greater radiosensitivity of the embryo irradiated in vitro in comparison to the embryo irradiated in vivo.
Critical review of articles regarding pregnancy exposures in popular magazines
Authors: Gunderson‐Warner Sandi , Martinez Lynn P. , Martinez Israel P. , Carey John C. , Kochenour Neil K. , Emery Maury G.
Published: June 2005

To determine the scope of teratogen information available to the public through the media, a survey of 15 popular magazines was conducted. All 1985 issues of the selected magazines were reviewed for articles addressing pregnancy exposure concerns, yielding 56 articles from 10 magazines. The remaining 5 publications provided no pertinent articles. Two health professionals, both experienced teratology counselors, independently rated each article for accuracy of content and quality of presentation based on standardized evaluation criteria. The findings were compared and agreement for all criteria in each article was reached by the 2 reviewers. Regarding the quality of the information in the 56 articles, 31 (55.4%) were scored as misleading or inaccurate. On examination of overall presentation, 26 (46.4%) were rated as alarming and 8 (14.3%) presented a false sense of security; 22 (39.3%) provided a balanced presentation. A review of the types of articles rated revealed 19 (33.9%) general overviews of pregnancy issues, 18 (32.1%) news stories, 17 (30.4%) question‐and‐answer columns, and 2 (3.6%) feature stories. Of the reviewed papers, 7 (12.5%) included a citation from which the primary data could be obtained and only 14 of the articles (25%) suggested that the reader contact her/his healthcare provider regarding the issues. We conclude that the information available in popular magazines regarding exposures in pregnancy is frequently misleading, alarming, and unsupported by the scientific literature.
Interlitter variability and developmental stage of day 11 rat embryos produced by overnight and morning short‐period breeding regimens
Authors: Fujinaga Masahiko , Jackson Ethan C. , Baden Jeffrey M.
Published: June 2005

Day 11 rat embryos produced by overnight and morning short‐period breeding regimens were compared for differences in interlitter variability and stage of development. Female Sprague‐Dawley rats were mated either overnight (5 PM‐9 AM, n = 22) or for 2 hr in the morning (8–10 AM, n = 20), and the presence of a vaginal plug was determined (day 0). At 11 AM on day 11 of gestation, rats were killed and embryos were examined for crown‐rump length, somite number, and general morphology; protein content was determined later. There were no differences in mean number of implantations, live embryos, and abnormalities between the two regimens. There were significant differences in mean crown‐rump length, somite number, and protein content but not in the magnitude of their variances. The difference in mean somite number was 1.2 (23.7 vs. 24.9), which corresponds to a time difference in development of approximately 2 hr. The range of mean somite number in morning short‐period breeding group was 3.2 (22.2–25.4), corresponding to approximately 5.3 hr. These results are inconsistent with the popularly held hypothesis that the timing of fertilization is the major cause of interlitter variability.
Effects of sustained dietary ethanol on the ultrastructure of the visceral yolk‐sac placenta of the rat
Authors: Jollie William P.
Published: June 2005

The present investigation reports ultrastructural alterations in endodermal epithelial cells of the rat visceral yolk‐sac placenta that accompany alcohol‐induced changes in intracellular trafficking of endocytosed maternal serum proteins. Fine structural changes include restructuring of mitochondrial cristae (foliate to vesicular and tubular forms), beading of cisterns of granular endoplasmic reticulum, hypertrophy and hyperplasia of Golgi elements, differentiation of the Golgi membranes to a GERL configuration, and a notable increase in numbers of primary lysosomes. Such changes in ultrastructure suggest that exposure of this developing maternofetal exchange system to high levels of ethanol in maternal blood increases the production of primary lysosomes near term for proteolysis of maternal serum proteins within the visceral yolk‐sac epithelium. Near term, targeting of endocytosed protein to secondary lysosomes for proteolysis appears to be augmented; transcellular routing of maternal protein (e.g., IgG) for placental transport may be impeded. Thus significance of the observed changes in the fine structure of this placenta may relate to the mechanism(s) of action of maternal alcohol consumption on the acquisition of neonatal immunity, intrauterine growth retardation, and the production of congenital malformations.
Target tissue specificity of retinoic acid‐induced stress proteins and malformations in mice
Authors: Anson J. F. , Laborde J. B. , Pipkin J. L. , Hinson W. G. , Hansen D. K. , Sheehan D. M. , Young J. F.
Published: June 2005

Retinoic acid (RA) is teratogenic in rodents and also induces the synthesis of stress proteins in fetal mouse limb buds. To determine if the RA induction of stress proteins is target tissue specific, pregnant CD‐1 mice were gavaged with 100 mg/kg RA on day 11 of gestation, and nuclei isolated from tissues susceptible to RA‐induced malformations (target tissues) as well as nuclei isolated from nontarget tissues were examined for stress protein synthesis and malformations. Forelimb and hindlimb (target tissues), as well as heart and tail (nontarget tissues), were removed from embryos 2.5 hours after RA treatment (1.5 hr after [3H]leucine labeling). Cell nuclei were isolated, stained with a DNA specific fluorochrome, propidium iodide, and sorted from the G0 + G1 and G2 + M phases of the cell cycle. Forelimb and hindlimb target tissues showed the synthesis in these embryonic nuclear proteins of an 84,000 relative molecular mass (Mr) protein and a 90,000 Mr protein following RA treatment. Two 20,000–25,000 Mr stress proteins were also labeled both in forelimb and hindlimb. Forelimb and hindlimb from untreated dams showed no stress protein labeling. Neither heart nor tail, nontarget tissues, showed any stress protein labeling following RA treatment. Classical teratological evaluation of embryos treated on GD 11 and sacrificed on GD 17 showed that 100% of the fetuses had forelimb and/or hindlimb malformations, while no malformations were observed in either the heart or tail. Based on the correlation of teratological anomalies with the identification of stress proteins in target tissue only, we postulate that stress proteins may be involved in the teratogenic process. Further work is necessary to establish whether a causal relationship exists.
Holoprosencephaly in a fetal macaque (Macaca nemestrina) following weekly exposure to ethanol
Authors: Siebert Joseph R. , Astley Susan J. , Clarren Sterling K.
Published: June 2005

Previous studies in rodents have indicated that the facial changes of fetal alcohol syndrome (FAS) closely resemble those of a mild form of holoprosencephaly. In order to examine this relationship in non‐human primates, we evaluated a 133‐day gestation macaque (Macaca nemestrina) with holoprosencephaly, median cleft lip and palate, and encephalocele. The mother had been given ethanol once per week (1.8 g/kg body weight) from weeks 2 to 19 postconception. Diagnosis of holoprosencephaly was made following ultrasound evaluation for polyhydramnios and delivery of the female fetus by caesarean section. Another fetus of identical age was delivered by caesarean section for use as a control. Both fetuses were studied by anthropometric, gross, radiographic, and histologic techniques. In the fetus exposed to alcohol, no extracranial anomalies were identified and the karyotype was normal. The brain was micrencephalic, with absent olfactory bulbs, tracts, optic nerves and chiasma, fused frontal lobes, and a single, dilated lateral ventricle; a parietooccipital encephalocele consisted of thin, dysplastic cortex bordering the ventricle; the cerebellum was dysplastic and superiorly displaced. Within the craniofacial complex, anophthalmia was bilateral; premaxillary components were absent, palatal shelves separate, the maxillae closeset, and the ethmoid bone small and deformed. Most of these defects are similar to those encountered in humans with holoprosencephaly and support the hypothesis of shared etiologic and pathogenetic relations between the facial anomalies of fetal alcohol syndrome and holoprosencephaly.
Ameltolide. I: Developmental toxicology studies of a novel anticonvulsant
Authors: Higdon Gary L. , McKinley Edmund R. , Markham Janet K.
Published: June 2005

Ameltolide, a novel anticonvulsant agent, has been shown in animal models to be effective in controlling seizures. The developmental toxicity of ameltolide was evaluated in two species. Naturally mated rats and rabbits were dosed once daily by gavage on gestation days (GD) 6–17 and 6–18, respectively. Rats were given doses of 0, 10, 25, or 50 mg/kg; rabbits were given 0, 25, 50, or 100 mg/kg. Laparotomy was performed on rats on GD 20 and on rabbits on GD 28. In rats, maternal toxicity was indicated at the 25‐ and 50‐mg/kg dose levels by depressed body weight gain. Fetal body weight was depressed at the 50‐mg/kg dose level. Fetal viability and morphology were not affected. The no‐observed effect levels (NOEL) for adult and developmental toxicity in the rat were 10 and 25 mg/kg, respectively. In rabbits, maternal toxicity was indicated by a net loss in body weight at the 50‐ and 100‐mg/kg dose levels. Fetal viability and body weight were depressed at the 100 mg/kg dose level. Shortened digits occurred on the right forepaw of one fetus at the 50‐mg/kg dose level (in conjunction with severe maternal toxicity) and on the hindpaws of two fetuses from separate litters at the 100‐mg/kg dose level. Incomplete ossification of the phalanges occurred on the forepaws of nine fetuses from four litters at the 100‐mg/kg dose level. Ameltolide was weakly teratogenic in the rabbit. The NOEL for adult and developmental toxicity in the rabbit was 25 mg/kg.
Effects of the Ay gene on susceptibility to hydrocortisone fetotoxicity and teratogenicity in mice
Authors: Teramoto Shoji , Hatakenaka Noriyuki , Shirasu Yasuhiko
Published: June 2005

Effects of the Ay gene, a coat color gene, on susceptibility to hydrocortisone fetotoxicity and teratogenicity were investigated by using the congenic strain of C57BL/6‐Ay (Ay/a) which had been maintained by repeated back‐crosses of the Ay gene to the C57BL/6 (a/a) background. Matings were conducted as follows (female × male): group I, a/a × a/a; group II, a/a × Ay/a; and group III, Ay/a × a/a. Pregnant females were subcutaneously given daily doses of 0, 12.5, 25, or 50 mg/kg of hydrocortisone on days 10–13 of pregnancy. On day 18 of pregnancy, fetuses were sexed, weighed, and examined for external abnormalities. In group I, the mean fetal weight was significantly decreased at a dose of 25 mg/kg or more. The incidences of cleft palate were 3.2 and 22.7% at 25 and 50 mg/kg, respectively. In group II, in which half of the fetuses were expected to carry the Ay gene, the mean fetal weight was decreased significantly at 12.5 mg/kg or more. The incidence of cleft palate in group II at 50 mg/kg was 44.2%, which was significantly higher than that in group I. In group III, in which maternal mice as well as half of their fetuses carried the Ay gene, a decrease in the mean fetal weight was greater than in group II. In addition, the mean percentage of fetal resorptions was significantly increased at 50 mg/kg. The incidence of cleft palate in group III was significantly increased at 25 mg/kg (10.5%) when compared with those in groups I and II. These results indicate that the Ay gene may be associated with susceptibility to hydrocortisone fetotoxicity and teratogenicity in mice.
Effect of ACE inhibition on the fetal kidney: Decreased renal blood flow
Authors: Martin Rick A. , Jones Kenneth L. , Mendoza Arturo , Barr Mason , Benirschke Kurt
Published: June 2005

The kidneys of nine fetuses whose mothers were chronically hypertensive were examined microscopically. Three of these mothers used antihypertensive agents throughout pregnancy including one who used an angiotensin‐converting enzyme (ACE) inhibitor. The tubular defects found in these kidneys were compared to the kidneys of 20 normal controls, 13 fetuses with various multiple malformation syndromes and six cases of the twin to twin transfusion syndrome. Evidence from these cases as well as the literature suggest that the primary mechanism by which ACE inhibitors affect development of the fetal kidney is through decreased renal blood flow. © 1992 Wiley‐Liss, Inc.
The warfarin embryopathy: A rat model showing maxillonasal hypoplasia and other skeletal disturbances
Authors: Howe Andrew M. , Webster William S.
Published: June 2005

Sprague‐Dawley rats were given daily subcutaneous doses of sodium warfarin (100 mg/kg) and vitamin K1 (10 mg/kg) for up to 12 weeks, starting on the day after birth. This dosing regimen creates an extrahepatic vitamin K deficiency while preserving the vitamin K‐dependent processes of the liver. Control rats received either vitamin K1 only or were untreated. All rats survived without any signs of hemorrhage. The warfarin‐treated rats developed a marked maxillonasal hypoplasia associated with a 11–13% reduction in the length of the nasal bones compared with controls. The length of the posterior part of the skull was not significantly different from controls. In the warfarin‐treated rats, the septal cartilage of the nasal septum showed large areas of calcification, not present in controls, and abnormal calcium bridges in the epiphyseal cartilages of the vertebrae and long bones. The ectopic calcification in the septal cartilage may have been the cause of the reduced longitudinal growth of the nasal septum and the associated maxillonasal hypoplasia.

It is proposed that (1) the facial features of the human warfarin embryopathy are caused by reduced growth of the embryonic nasal septum, and (2) the septal growth retardation occurs because the warfarin‐induced extrahepatic vitamin K deficiency prevents the normal formation of the vitamin K‐dependent matrix gla protein in the embryo. © 1992 Wiley‐Liss, Inc.