bluuebunny/crossref_metadata_2025 huggingface dataset:
Potentiating effect of caffeine on the teratogenicity of acetazolamide in C57BL/6J mice
Authors: Beck Sidney L. , Urbano Charissa M.
Published: June 2005

Pregnant C57BL/6J mice were treated with 0 or 50 mg of caffeine (CAFF) per kg, and 0, 200 mg/kg (L) or 1,000 mg/kg (H) of acetazolamide (ACZM) during day 9 of gestation (9DPC). Individual fetuses were examined for gross morphological abnormalities and skeletal variations. The increase in fetal malformations seen, especially right forelimb electrodactyly, was augmented at both dose levels of acetazolamide by concomitant exposure to caffeine. Both frequency and severity of ectrodactyly were potentiated by caffeine. Skeletal examination revealed a reduction of the number of ossified cervical and caudal vertebral centra among litters exposed to ACZM at either dose. In either case (ACZM‐H, ACZM‐L) that effect was augmented by co‐administration of CAFF. The first cervical vertebra (C1) appeared to provide the most sensitive index of teratogenic exposure.

This study provides evidence that a subteratogenic dose of caffeine can potentiate the teratogenic effect of acetazolamide in C57BL/6J mice when dams are treated on day 9 of gestation. In addition, skeletal examination provided evidence that simultaneous treatment with both agents delayed fetal development. Many litters exposed to ACZM or both agents displayed a reduction in skeletal ossification even in the absence of gross morphological abnormalities, suggesting that ossification can be used as an indicator of prenatal exposure to potentially harmful substances in the C57BL/6 mouse strain.
Chemically induced alterations in maternal homeostasis and histology of conceptus: Their etiologic significance in rat fetal anomalies
Authors: Khera K. S.
Published: June 2005

Possible relationships between maternal acid‐base‐electrolyte imbalance, histological changes in the maternal/extraembryonic tissues (decidua, placenta, membranes enclosing cavities), and fetal anomalies induced by maternotoxic doses of ethylene glycol, sodium salicylate, and cadmium chloride in rats were investigated. Acid‐base‐electrolyte, histologic and, teratologic studies were conducted concurrently with, as far as feasible, a similar protocol. Ethylene glycol caused 1) maternal homeostatic changes including metabolic acidosis and hyperosmolality, 2) extraembryonic lesions with degeneration of allantois and reduced villigenesis being more prevalent, and 3) materno‐fetal effects such as decreases in fetal and maternal body weights, decreased maternal food intake, and fetal abnormalities (vertebral, rib, and sternebral defects). Few of these changes occurred when NaHCO3, an endogenous agent known to correct metabolic acidosis, was coadministered with ethylene glycol. Ethylene glycol‐induced maternal metabolic acidosis, concurrent with hyperosmolality, was suspected to contribute toward reduction in villigenesis and fetal anomalies, including body weight reductions. Sodium salicylate induced the following: 1) mild maternal acidosis, hypokalemia, and hypophosphatemia with no significant change in pH; 2) maternal hemorrhage in extraembryonic cavities, papillary proliferation of the visceral yolk sac endoderm, and failure to form the chorioallantoic labyrinth; and 3) resorptions, hydrocephaly, rib defects, and fetal body weight reduction. Upon simultaneous treatment with sodium salicylate, NaHCO3 significantly reduced, and NH4Cl enhanced the incidence of the above histologic and teratologic effects, without significantly altering acid‐base values. An etiologic association between the above salicylate‐induced maternal and extraembryonic lesions and teratogenicity was likely. Cadmium chloride, whether administered by the intraperitoneal (ip) or intravenous (iv) route, caused 1) hydrocephaly, anophthalmia, vertebral and rib defects, reduction in fetal body weight, resorptions and maternal toxicity (acute peritonitis by the ip route only), and 2) extensive necrosis and hemorrhage in the decidua basalis, hemorrhage in the ectoplacental cone and around Reichert's membrane, and absence of chorioallantoic labyrinth. An etiologic relationship between these teratologic and histologic effects seemed probable, since both were dose‐related. From the above studies, it was hypothesized that maternal factors—metabolic acidosis, hyperosmolality, hemorrhages in the ectoplacental cone, extraembryonic cavities, and around Reichert's membrane, and necrosis of decidua basalis—may have, directly or indirectly, reduced fetal nutrition and materno‐embryonic gaseous exchange, which ultimately altered fetal development.
Comparisons of the effects of TCDD and hydrocortisone on growth factor expression provide insight into their interaction in the embryonic mouse palate
Authors: Abbott B. D. , Harris M. W. , Birnbaum L. S.
Published: June 2005

Cleft palate (CP) can be induced in embryonic mice by a wide range of compounds, including glucocorticoids and 2,3,7,8‐tetrachlorodibenzop‐dioxin (TCDD). Hydrocortisone (HC), a glucocorticoid, retards embryonic growth producing small palatal shelves, while TCDD exposure blocks the fusion of normally sized shelves. TCDD induction of CP involves altered differentiation of the medial epithelial cells. Recent studies indicate that growth factors such as EGF, TGF‐α, TGF‐β1, and TGF‐β2 are involved in palatogenesis, regulating proliferation, differentiation, and extracellular matrix production. A synergism has been observed between HC and TCDD in which doses too low to induce CP alone are able to produce >90% incidence when coadministered. In the present study a standard teratology protocol was performed in C57BL/6N mice to examine the synergism at doses lower than those previously published. Data from this study indicate synergistic interactions at doses as low as 3 μg TCDD/kg + 1 mg HC/kg. This extreme sensitivity suggests the involvement of a receptor‐mediated mechanism possibly resulting in altered regulation of gene expression. Mechanisms of interaction were further studied by comparing growth of the shelves, fate of the medial epithelium, and expression of growth factor mRNAs and peptides. Pregnant mice were dosed on GDs 10–13 with HC (100 mg/kg sc) or with HC (25 mg/kg sc) + TCDD (3 μg/kg orally), doses producing 30% and 99% CP, respectively. The interaction between HC and TCDD results in a small HC‐like palate, rather than the morphology typical of TCDD‐induced clefting. Both compounds inhibited programmed cell death of the medial epithelium, which instead differentiated into an oral‐like epithelium. The alterations in growth factor expression after HC or HC + TCDD were similar. Expression of EGF, TGF‐β1, TGF‐β2, and EGF receptor increased in specific palatal regions. Increased levels of mRNA were observed only for TGF‐β1. The effects of TCDD alone on growth factor expression differ from those seen with HC or HC + TCDD. These divergent effects on growth factor expression may contribute to the differences in shelf size and thus to the different mechanisms of HC and TCDD clefting. Thus the synergism between HC and TCDD may involve similar and potentially additive effects on regulators of proliferation and differentiation in the palate, but additional contributing factors cannot be excluded.
The functional importance of the oviduct in neonatally estrogenized mouse females for early embryo survival
Authors: Halling Anders , Forsberg John‐Gunnar
Published: June 2005

Eight‐week‐old virgin untreated female mice were induced to ovulate using equine chorionic gonadotropin (eCG) and human chorionic gonadotropin (hCG), and were then caged with males overnight. Females with a vaginal plug on the following morning were killed 24 hours later and 2‐cell embryos were flushed from the oviduct. These embryos were transferred to the oviduct of 8‐week‐old control females, to females of the same age treated with 5 μg diethylstilbestrol (DES) sc in olive oil for the first 5 days after birth, or to females treated with 1 μg estradiol‐17β for 2 days before and 2 days after transfer (estrogen dominated/ED/females). Two days after transfer, a significantly lower number of embryos were recovered from oviducts of DES females compared to control females and a still lower number from ED females. The recovered embryos were cultured in vitro for 4 days testing trophoblast outgrowth (“implantation stage”). The incidence of embryos reaching this stage after development in DES‐exposed oviducts was only half of that for embryos passing control oviducts or ED oviducts. It is concluded that the adult oviductal environment in neonatally DES‐treated females significantly decreases early embryo developmental potential. The oviductal factor(s) harmful to the embryo may be related to a persistent and possibly increased level of circulating estrogen level in DES females.
Valproic acid‐induced spina bifida: A mouse model
Authors: Ehlers Katharine , Stürje Helga , Merker Hans‐Joachim , Nau Heinz
Published: June 2005

Prenatal exposure to the antiepileptic drug valproic acid (VPA) has been associated with the formation of spina bifida aperta, meningocele, and meningomyelocele in the human. Until now, a direct relationship between VPA application and spina bifida has not been experimentally demonstrated. VPA was known only to induce exencephaly in mice, a defect of the anterior neural tube. Maximal sensitivity toward production of this defect was on day 8 of gestation (plug day = day 0). The closure of the posterior neuropore occurs later in the development of mice than the closure of the anterior neuropore. To investigate whether there is a direct relationship between VPA application during pregnancy and induction of spina bifida in mice, we administered various doses of the drug on day 9 of gestation, at three time intervals (at 0, 6, and 12 hr). This administration of VPA produced spina bifida aperta and spina bifida occulta in mice. High doses of VPA (3 × 450 and 3 × 500 mg/kg) induced a low rate of spina bifida aperta in the lumbosacral region. High incidences of spina bifida occulta, a less serious form of spina bifida, were induced with lower doses. This malformation was demonstrated in double‐stained fetal skeletons by measurements of the distance between the cartilaginous ends of each vertebral arch. The occurrence of this defect and its localization was dose‐dependent. The lumbar region was affected by all doses investigated (3×300, 3×350, 3×400, 3×450, and 3×500 mg/kg). The sacral/coccygeal region was affected additionally, but with higher doses (3×400, 3×450, and 3×500 mg/kg). A comparison of the results obtained with day 16 and 17 control fetuses showed that the pattern of gaps present in the lumbar and sacral region of the spinal cord in treated groups was drug‐specific and not related to a developmental delay. Our results indicate that multiple administrations of VPA on day 9 of gestation in mice result in a low incidence of spina bifida aperta and a high incidence of spina bifida occulta, and provides a relevant model for the study of human spina bifida defects.
Morphological changes in long bone development in fetal akinesia deformation sequence: An experimental study in curarized rat fetuses
Authors: Rodríguez José I. , Palacios José , Ruiz Antonio , Sanchez Miguel , Alvarez Ignacio , Demiguel Enrique
Published: June 2005

In order to investigate the transverse growth of the long bones during intrauterine development in the fetal akinesia deformation sequence (FADS), we studied curarized rat fetuses. Curarization was performed by daily subcutaneous administration of D‐Tubocurarine from day 17 of gestation until term. Experimental fetuses were compared with a sham‐operated control group. The total area and perimeter, the absolute and relative amount of periosteum and bone trabeculae, the major and minor axes, and the elongation factor were measured from histological cross‐sections of the femoral metaphysis and diaphysis using an IBAS 1 image analysis system. Curarized rat fetuses showed growth retardation, a short umbilical cord, and multiple articular contractures, a phenotype consistent with FADS. Alterations in femoral shape and transverse growth that affected the diaphysis were noted in these fetuses. These included a decrease of total cross‐section area and reduction of the absolute and relative amounts of bone trabeculae with marked thinning of the periosteum. Femoral cross‐sections was rounder than controls. These results evidenced an impairment of the membranous (periosteal) ossification of long bones produced by immobilization and/or decrease of muscular strength, and support our previous clinical findings of bone hypoplasia and osteopenia in FADS.
Inositol deficiency increases the susceptibility to neural tube defects of genetically predisposed (curly tail) mouse embryos in vitro
Authors: Cockroft D. L. , Brook F. A. , Copp A. J.
Published: June 2005

Curly tail (ct/ct) mouse embryos, which have a genetic predisposition for neural tube defects (NTD), were grown in culture from the 2‐5 somite stage, before the initiation of neurulation, up to the 22‐24 somite stage, when closure of the anterior neural tube is normally complete. The embryos were cultured in whole rat serum or in extensively dialysed serum supplemented with glucose, amino acids, and vitamins, with inositol omitted or added at concentrations of 2, 10, 20, and 50 mg/1. Two strains were used as controls; CBA mice, which are related to curly tails, and an unrelated PO stock. It was found thatct/ctembryos were particularly sensitive to inositol deficiency; both they and the CBA embryos showed a similar high incidence of cranial NTD after culture in inositol deficient medium (12/17 and 11/18, respectively). Furthermore, the lowest dose of inositol had no effect on the frequency of head defects inct/ctmice, though it halved the incidence in CBA embryos. With higher inositol concentrations, the majority of ct/ct embryos completed head closure normally, and their development was generally similar to that obtained in whole serum. PO embryos showed a lower proportion (5/19) of cranial NTD in the inositol deficient medium than the other two strains, and this was further reduced by even the lowest inositol dose.
Identical phalangeal defects induced by phenytoin and nifedipine suggest fetal hypoxia and vascular disruption behind phenytoin teratogenicity
Authors: Danielsson Bengt R. G. , Danielson Margaretha , Rundqvist Eva , Reiland Sven
Published: June 2005

In previous experimental studies in rabbits, we have shown that vasodilating drugs (including nifedipine) cause distal digital defects. These defects were preceeded by edema, hemorrhage, and finally necrosis of the developed cartilage in the phalanges. The underlying mechanism is most likely a fetal hypoxic response, secondary to maternal hypotension and decreased uteroplacental blood flow. Since phenytoin is known to cause distal digital defects both in man and rabbits, we decided to compare the defects provoked by oral administration of phenytoin (100 mg/kg) versus nifedipine (8.3 mg/kg) to New Zealand White rabbits on days 6‐18 of gestation. In order to investigate phasespecificity, phenytoin (150 mg/kg) was given on days 14‐17. The result of single dose administration on day 16 of phenytoin (300 mg/kg) versus nifedipine (33.2 mg/kg) was also studied. In this latter experiment maternal heart rate was measured up to 21 hours after phenytoin administration. Phenytoin induced digital defects identical with those produced by nifedipine and caused marked maternal cardiodepression. The defects consisted of a reduction, absence, or abnormal structure of the distal phalanges. The distal phalanx of the fourth digit on the hindpaw was the first to be affected, with inclusion of other phalanges, both on the hind‐ and forepaws, with increasing dose. The sensitive period for induction and histological appearance of these defects was identical for phenytoin and nifedipine. These results suggest that vascular disruption due to a fetal hypoxic response lies behind phenytoin teratogenicity, as has been shown for vasodilators. A cardiodepressive action on the maternal and fetal hearts, possibly in combination with decreased uteroplacental blood flow, is discussed as a probable factor behind phenytoin teratogenicity.
Birth prevalence of down syndrome in a predominantly Latino population: A 15‐year study
Authors: Wilson Miriam G. , Chan Linda S. , Herbert William S.
Published: June 2005

The birth prevalence of Down syndrome (DS), although decreasing in parts of the world, is not known in many specific subpopulations. The rate of DS for live births was determined for a 15‐year period (1974‐1988) at the Los Angeles County‐University of Southern California Medical Center, which is a large public hospital serving a predominantly Latino population. DS was ascertained primarily by clinical monitoring of newborn infants. The overall rate of DS was 1.60/1,000 live births and had minimal fluctuation throughout the 15 years. The rate of DS for Latino births was 1.69/1,000 live births, 1.67 when adjusted for maternal age, and 1.75 when corrected for prenatal diagnosis. The high rate of DS in the Latino population was associated with advanced maternal ages and increased maternal‐age specific rates for DS, especially in the age ranges of 30 to 34 and 40 to 44 years, when compared with other studies.
Thyroid hormone differentially regulates cellular development in neonatal rat heart and kidney
Authors: Slotkin T. A. , Seidler F. J. , Kavlock R. J. , Bartolome J. V.
Published: June 2005

The role of thyroid hormone in the control of cardiac and renal cell development was examined in neonatal rats made hyperthyroid by administration of triiodothyronine (T3, 0.1 mg/kg s.c. on postnatal days 1‐5) or hypothyroid by administration of propylthiouracil (PTU, 20 mg/kg s.c. given to dams on gestational day 17 through postnatal day 5 and to pups on postnatal days 1‐5). Indices of total cell number (total DNA per tissue), cell packing density (DNA per g tissue), and relative cell size (protein/DNA ratio) were evaluated from birth through young adulthood. PTU administration led to primary shortfalls in cell number that were of similar magnitude in both tissues, but persisted somewhat longer in the kidney than in the heart. Deficits in cell packing density and cell size in the hypothyroid animals were secondary to the effect on cell number, displaying smaller magnitudes of effect and a lag in appearance and disappearance of the deficits compared to that for total DNA; indeed, the phase in which tissues were restoring their cell numbers was accompanied by increased cell packing density, reflecting a more rapid restitution of cell numbers than tissue weight or cell size. In contrast to the relatively similar effects of PTU on developing cardiac and renal cells, the effects of T3 were selective for the heart. Although T3 caused general growth impairment, it evoked marked cardiac overgrowth that was accompanied by a striking increase in cell number and a small increase in cell size. The cardiac hyperplasia is unique to the developing animal, as post‐replicative heart cells in adult animals show only hypertrophy in response to thyroid hormone. The time course of appearance and disappearance of the effects of T3 on the indices of cardiac cell development suggested that the hormone shifted maturation such that cell replication was initiated and terminated earlier than in control animals. The results obtained in this study thus indicate that thyroid hormone plays two distinct and separable roles in modulation of cellular development: basal levels of hormone are required to maintain cell acquisition in all tissues but, in addition, there is a more specific role in cardiac cells in setting the timing of onset and disappearance of cell replication.
First trimester maternal medication use in relation to gastroschisis
Authors: Werler Martha M. , Mitchell Allen A. , Shapiro Samuel
Published: June 2005

In a case‐control surveillance program, first trimester medication use was studied in relation to gastroschisis. There were 76 cases of gastroschisis which were compared with 2,142 controls with other major malformations. For pseudoephedrine use, we found a significantly elevated relative risk of 3.2 (95% confidence interval, 1.3‐7.7), with adjustment for confounding. Multivariate relative risks for analgesic/antipyretics and another decongestant were as follows: salicylates, 1.6 (0.9‐2.7); acetaminophen, 1.7 (1.0‐2.9); ibu‐profen, 1.3 (0.4‐3.7); and phenylpropanolamine, 1.5 (0.4‐5.4). No increases in risk were identified for use of antihistamines, antibiotics, oral contraceptives, or spermicides.

Because salicylates, pseudoephedrine, and phenylpropanolamine are vasoactive, the elevated risks for these drugs support the hypothesis of vascular disruption in the etiology of gastroschisis. We therefore examined maternal use of vasoactive medications in relation to a second case group of 416 infants with hetereogeneous defects suspected to have a vascular etiology. Relative risks for salicylates, ibuprofen, pseudoephedrine, phenylpropanolamine, and other decongestants approximated unity.

These positive associations must be considered tentative. They have not been reported previously and should be confirmed independently. Also, acetaminophen, which may be taken for the same indications as salicylates and decongestants, but is not thought to be vasoactive, was associated with gastroschisis, suggesting that identified associations may be due to an underlying maternal illness.
Correlation of increased levels of class I MHC H‐2Kk in the placenta of murine trisomy 16 conceptuses with structural abnormalities revealed by magnetic resonance microscopy
Authors: Kornguth Steven , Bersu Edward , Anderson Mark , Markley John
Published: June 2005

Murine trisomy 16 (mts16) placentas and fetuses, 17‐day gestation age, were examined histologically and by magnetic resonance imaging at 9.4 T and compared with control littermate tissues. Placentas were studied by immunohistochemical methods, at 15‐days gestational age, for expression of the major histocompatibility complex (MHC) class I H‐2Kk cell surface marker. Immunohistochemical studies revealed a markedly increased expression of the MHC marker H‐2Kk on cells in the labyrinth of the placenta of mts16. There were differences between the magnetic resonance (MR) images of the trisomic and normal placentas, which may be correlated with the increased expression of H‐2Kk in the mts16 placental labyrinth. The decidual and labyrinthine components of the normal placentas showed similar high signal intensities (SI) while in trisomic placentas a marked high SI was characteristic only of the decidual region on proton spin density images. The MRI also revealed a smaller cerebellum in the ts16 fetuses. The potential effects of the compromised structure of the placental labyrinth and the overexpression of the H‐2Kk marker on the mts16 neural and placental dysgenesis are discussed.
Variation in development of rat embryos at the presomite period
Authors: Fujinaga Masahiko , Baden Jeffrey M.
Published: June 2005

Rat embryos at a single gestational time in the presomite period were studied for their variation in development and their fate after culture. They were explanted at 8 A.M. on day 9 of gestation from timed‐pregnant Sprague‐Dawley rats which were obtained by mating between 8 and 10 A.M. (plug day = day 0). In the first experiment, a total of 203 embryos from 20 litters were examined for their variation in development. Several dimensions of embryo/egg cylinder were measured and development of various embryonic/extraembryonic structures were assessed using a scoring system that we developed for the present study. Embryos were then divided into different stages of development based on their scores using the staging system that we developed previously. A large variation in developmental stage was demonstrated; the youngest embryo was at the early primitive streak stage with no signs of amniotic folds and the oldest one was at the late neural plate stage with a foregut pocket but without visible somites. No strong correlation was demonstrated between developmental stage and size of embryo/egg cylinder, nor between developmental stage and development of the proamniotic tube, ectoplacental cavity, or allantois. In the second experiment, embryos were explanted at the same time and those at different stages were cultured separately in rotating bottles and their outcomes were compared after 49 hours. The difference in mean somites number of embryos cultured from the mid primitive streak and late neural plate stages was 6.1. This difference corresponds to approximately 10 hours based on the known linear increase of somites number on day 11 of approximately 0.6 somites per hour. These results indicate a large variation in development of presomite period embryos supposedly of the same gestational age and suggest the importance of careful staging at the time of explantation if precision is needed for whole embryo culture experiments. © 1992 Wiley‐Liss, Inc.
Increased postimplantation loss and malformations among the F2 progeny of male rats chronically treated with cyclophosphamide
Authors: Hales Barbara F. , Crosman Kellie , Robaire Bernard
Published: June 2005

Cyclophosphamide, administered to the male rat, produces increased pre‐ and postimplantation loss in the progeny as well as an increase in the numbers of malformed and growth retarded fetuses. The purpose of this study was to determine whether the adverse effects of chronic paternal cyclophosphamide exposure are transmissible to the next generation, the F2 progeny. Adult male rats were treated by gavage daily with saline or with cyclophosphamide (3.4 or 5.1 mg/kg) for 4 or 18 weeks and mated. The male and female offspring in each treatment group (F1 generation) were randomly mated. The resulting pregnant females were killed on day 20 of gestation to evaluate progeny outcome in the F2 generation. There was a significant increase in postimplantation loss among the offspring of the group whose fathers had been treated with cyclophosphamide at a dose of 5.1 mg/kg/day. Exposure to a dose of 5.1 mg/kg/day of cyclophosphamide also resulted in an F2 generation with a significantly decreased mean fetal weight per litter and a significant increase in the number of malformed fetuses. The malformations observed among the F2 progeny included open eyes, omphalocele, generalized edema, syndactyly, gigantism, and dwarfism. Thus, exposure of the father to cyclophosphamide does result in a specific and heritable alteration in the fertility of the surviving “apparently normal” F1 progeny. Interestingly, the adverse consequences of exposure of male rats to cyclophosphamide are similar in the F2 generation to those previously reported for the F1 progeny. © 1992 Wiley‐Liss, Inc.
Interpretation of recurring weak associations obtained from epidemiologic studies of suspected human teratogens
Authors: Khoury Muin J. , James Levy M. , Flanders W. Dana , Erickson J. David
Published: June 2005

Epidemiological studies of suspected human teratogens not infrequently lead to recurring weak or moderate associations (relative risks or odds ratios ranging from >1 to 3 for adverse effects and from 1/3 to <1 for protective effects) between specific defects and prenatal exposures. Examples of such associations include cigarette smoking and oral clefts (odds ratios between 1 and 2) and periconceptional multivitamin/folic acid supplementation and neural tube defects (odds ratios from 1/3 to 1). In this paper, we illustrate that low relative risk recurring in well‐designed studies may reflect underlying biologic mechanisms and should not be readily dismissed. Low relative risks could be the result of a combination of the following factors: 1) unmeasured confounding, 2) exposure misclassification (often related to the inability to pinpoint relevant dose and timing), 3) outcome misclassification (related to the etiologic heterogeneity of birth defects), 4) biologic interactions (related to teratogenic effects in population subgroups defined by genetic susceptibility or the presence of other exposures), and 5) differential prenatal survival (related to the combined impact of the exposure and the defect on prenatal survival). These issues can be addressed in epidemiologic studies by using biological markers of exposure and susceptibility, dysmorphologic evaluation of affected infants, subgroup analysis for etiologic heterogeneity, a search for biologic interactions, and the use of prospective cohort studies. Finally, low relative risks in the face of common exposures can reflect an important public health contribution of the exposure to the occurrence of the defect in the population. © 1992 Wiley‐Liss, Inc.
Embryotoxicity of T‐2 toxin and secalonic acid in embryonic chicks varies with the site of administration
Authors: Veselý D. , Veselá D. , Jelínek R.
Published: June 2005

A crucial role of the site of administration in the sensitivity of the alternative system using chick embryo for testing embryotoxicity was demonstrated by morphological evaluation of the effects of T‐2 toxin and secalonic acid D, and by incorporation of [14C]sodium acetate radioactivity. Secalonic acid D, administered to 2‐, 3‐, and 4‐day‐old embryos in doses higher than 1 μg produced mostly malformations of the face (bilateral cleft beak, microphthalmia) while the teratogenic effects of T‐2 toxin were being limited to the embryonic trunk of 2‐day‐old embryos (rumplessness) after administering doses higher than 0.001 μg. In case of subgerminal and intraamniotic injections, the doses of both mycotoxins needed for producing embryotoxic effects comparable to those obtained with the more commonly used yolk sac injections appeared to be lower by one and two orders of magnitude, respectively. The results stress the need of using the shortest transport channel of test substances from the site of application to the target tissues of the embryo, when the maximum sensitivity and reproducibility of the test system are to be expected. © 1992 Wiley‐Liss, Inc.
Cocaine and single ventricle: A population study
Authors: Martin M. Louise , Khoury Muin J.
Published: June 2005

A recent case report by Shepard et al. (Teratology 43:113–117, 1991) suggested that single ventricle may result from maternal cocaine ingestion by inducing coronary occlusion in the developing fetal heart. We used data from the Atlanta Birth Defects Case‐Control Study and the Metropolitan Atlanta Congenital Defects Program (MACDP) to investigate the role of maternal cocaine ingestion in the induction of single ventricles. We identified through the MACDP 58 case infants with a single ventricle, 27 who were study subjects in the Atlanta Birth Defects Case‐Control Study, and 31 who were not. We conducted a case‐control study with the 27 Atlanta Birth Defects Case Control Study infants, frequency‐matched to control infants by race, hospital of birth, and calendar quarter of birth. None of the 27 case infants were exposed to cocaine during early pregnancy, but 7 (0.43%) of the control infants were exposed during early pregnancy. Using MACDP data, we conducted an analysis of trends for prevalence of single ventricle in the metropolitan area. No upward trend in single ventricle was detected for 1968 through 1990. Our data suggest that even if maternal cocaine ingestion during pregnancy is a cause of single ventricle, most cases appear to be unrelated to this exposure. © 1992 Wiley‐Liss, Inc.
Descriptive profile of birth defects among livebirths in Singapore
Authors: Thein M. M. , Koh D. , Tan K. L. , Lee H.‐P. , Yip Y. Y. , Tye C. Y. , Phoon W. O.
Published: June 2005

A case‐control study of birth defects was carried out in Kandang Kerbau Hospital in Singapore for a three‐year period from January 1986 until December 1988. This paper presents the descriptive profile of birth defects among livebirths seen in that hospital. Out of 44,842 livebirths, 678 babies were found to have birth defects, giving a prevalence of 15.13 per 1000 livebirths (95% CI 14.0–16.2). The musculoskeletal system was the most frequently affected system accounting for 161 cases with a prevalence of 3.59 per 1,000 livebirths (95% CI 3.06–4.19), followed by 111 cases with defects of the gastrointestinal system (2.47 per 1,000 livebirths 95% CI 2.04–2.98), 88 cases of chromosomal disorders (prevalence of 1.96 per 1,000 livebirths 95% CI 1.57–2.42), 78 cases with defects of the cardiovascular system (1.74 per 1,000 live‐births 95% CI 1.38–2.17), 73 cases with defects of the urogenital system (1.63 per 1,000 livebirths 95% CI 1.28–2.05), and 52 cases with defects of the central nervous system (1.16 per 1,000 livebirths 95% CI 0.87‐1.52). The prevalence of cleft lip, cleft palate in isolation, and cleft lip and palate combined was 1.72 per 1,000 livebirths and the occurrence of Down's syndrome was 1 in 700 livebirths. When reviewed 6 weeks postpartum, the rate of false positives at birth was 4%. In a control group of 709 “normal” cases at birth, the rate of cases not detected at birth but detected at 6 week follow‐up, false negatives was 0.84%. © 1992 Wiley‐Liss, Inc.
Rat hepatic glutathione S‐transferase‐mediated embryotoxic bioactivation of ethylene dibromide
Authors: Mitra Ashoke , Hilbelink Don R. , Dwornik Julian J. , Kulkarni Arun
Published: June 2005

The embryotoxic effects of ethylene dibromide (EDB) bioactivation, mediated by purified rat liver glutathione S‐transferases (GST), were investigated using rat embryos in culture. Significant EDB metabolism was observed with rat liver GST purified by affinity chromatography (specific activity of 188 ± 11.3 nmol/min/mg protein). The reaction was enzymatic in nature and the conjugation rate was proportional to the concentration of EDB (up to 0.75 mM) and the enzyme present in the reaction medium. EDB activation by 100 units (1 unit = 1 nmol of glutathione consumed per min) of purified rat liver GST caused a significant reduction in general development as measured by crown–rump length, yolk sac diameter, somite number, and the composite score for different morphological parameters (Brown and Fabro methodology). Structures most significantly affected were the central nervous and olfactory systems as well as the yolk sac circulation and allantois. The results of this study clearly indicate that under in vitro conditions, bioactivation of EDB by GST can lead to embryotoxicity. © 1992 Wiley‐Liss, Inc.
Avian model for 13‐cis‐retinoic acid embryopathy: Morphological characterization of ventricular septal defects
Authors: Hart Robin C. , Winn Kevin J. , Unger Elizabeth R.
Published: June 2005

In developing an avian model for 13‐cis‐retinoic acid (13cisRA) embryopathy, we found 13cisRA induced cardiovascular defects, especially Type I ventricular septal defects (VSDs) (Hart et al.: Teratology 41:463–472, '90). As the first step of investigating possible mechanisms, we have examined the light microscopic morphology of RA‐induced cardiovascular defects in chick embryos. Fertilized eggs were injected via yolk sac with 150 μg 13cisRA in dimethylsulfoxide (DMSO), DMSO or mock injection on embryonic day 5 (E5). On E6, E7, or E8, surviving embryos were sacrificed and fixed in 10% formalin. Thoracic blocks were exised, embedded in paraffin and serially sectioned through the heart, base to apex. Slides were stained, screened for tissue orientation, then coded and evaluated without knowledge of treatment group. Examination of serial sections permitted qualitative evaluation of conotruncal ridge volume, mesenchymal organization, necrosis and extent of fusion. Extent of fusion was the only parameter influenced by 13cisRA treatment. On E6, ridge fusion was incomplete in all groups at comparable levels. On E7, ridge fusion in 13cisRA‐treated embryos had not progressed as far proximally as in controls. By E8, there was a significant difference in the extent of fusion between 13cisRA‐treated and non‐RA‐treated groups. We conclude 13cisRA‐induced VSDs resulted from defective conotruncal ridge fusion and that the fusion defects did not result from decreased tissue volume, altered mesenchymal organization or increased necrosis. © 1992 Wiley‐Liss, Inc.
Clinical anophthalmia: An epidemiological study in Northeast Italy based on 368,256 consecutive births
Authors: Clementi Maurizio , Turolla Licia , Mammi Isabella , Tenconi Romano
Published: June 2005

We describe an epidemiological and clinical study of Clinical Anopthalmia in a population of consecutive live and stillborns enrolled in a hospital based registry of congenital malformations in Northeast Italy during the period from 1981 to 1989; 22 cases were detected among 368,256 births yielding a birth prevalence of 0.60 per 10,000 (95% CI 0.34–0.84); 20 cases were associated with at least one other major malformation. Malformation syndrome, association, or sequence was diagnosed in 13, while a non‐recognizable multiple defect pattern was observed in 7/20 (35%). A chromosomal anomaly was present in eight syndromic cases. No significant trend over time, nor space or time clusters, were detected. As most CAn cases are associated with other anomalies recognizable by ultrasound, a decreasing trend in its prevalence at birth is expected in the future. © 1992 Wiley‐Liss, Inc.
Importance of early exposure to 13‐cis retinoic acid to induce teratogenicity in the cynomolgus monkey
Authors: Korte Rainhart , Hummler Hans , Hendrickx Andrew G.
Published: June 2005

The teratogenic potential of 13‐cis retinoic acid (13‐cis RA) was further assessed in cynomolgus macaques (Macaca fascicularis) following exposure to two different regimens during the preorganogenic period to determine the influence of time of treatment on the 13‐cis RA malformation syndrome established previously (Hummler et al., Teratology, 42:263–272, 1990). In experiment (Exp) 1, 13‐cis RA was orally administered once daily (2.5 mg/kg) on gestational day (GD) 16–25 and twice daily (2 × 2.5 mg/kg) on GD 26–27. In Exp 2, the same oral dose was administered once daily on GD 10–20 and twice daily on GD 21–24. Although the ear was affected at about the same incidence (6/9, 67%) in Exp 1 as previously reported, the defects were less severe. Except for hypoplastic vermis of the cerebellum (2/9, 22%), no other defects were seen. In Exp 2, the teratogenic effects of 13‐cis RA on the craniofacial skeleton (1/9, 11%), external ear (5/9, 56%), and heart (2/9, 22%) were similar to that reported by Hummler et al.; however, no thymus or cerebellar malformations were observed. Analysis of the three different treatments (GD 16–27 in Exp 1, GD 10–24 in Exp 2, and GD 10–27 in Hummler et al.) suggests that the sensitive periods in the macaque are 1) craniofacial skeleton and heart GD 10–24, 2) thymus and cerebellum >GD 24, and 3) external ear GD 16–24, although the defects are less severe following the shorter exposure. Exposure to 13‐cis RA preceding onset of morphological organogenesis appears to be a requirement for 13‐cis RA embryopathy in the cynomolgus monkey. The external ear appears to be both a uniquely sensitive biomarker for 13‐cis RA teratogenicity and an indicator of embryotoxic severity. Finally, the longer period of drug administration (2.5 mg/kg, GD 10–25, and 2 × 2.5 mg/kg, GD 26–27) used by Hummler et al. is more suited to assessment of 13‐cis RA teratogenicity in macaques due to greater concordance with the 13‐cis RA syndrome in humans. © 1993 Wiley‐Liss, Inc.
Young maternal age and smoking during pregnancy as risk factors for gastroschisis
Authors: Haddow James E. , Palomaki Glenn E. , Holman Mary S.
Published: June 2005

Three maternal risk factors (maternal age, cigarette smoking, and infant's month of birth) have been reported to be associated with fetal gastroschisis. In order to study these risk factors further, a prospective population‐based study was designed, using 62,103 consecutive second‐trimester singleton pregnancies enrolling in a maternal serum alpha‐fetoprotein screening program between January 1, 1980 and April 30, 1989. Gastroschisis occurred in 21 of those pregnancies. Pregnancies in women younger than 20 years of age were at 7.3 times greater odds for being affected with gastroschisis than pregnancies in women aged 25 or older (95% confidence interval 2.4 to 22). For pregnant women aged 20 to 24 years, the odds were 1.9 times greater (95% confidence interval 0.7 to 5.0). Pregnant women who smoked cigarettes were at 2.1 times greater odds than non‐smokers (95% confidence interval 0.9 to 4.8). When these smoking data were combined with smoking data from two other published studies, the consensus odds ratio was 1.6 (95% confidence interval 1.2 to 2.2). Infant's month of birth was not associated with gastroschisis. Evidence from the present study and other published studies clearly establishes a greater risk for fetal gastroschisis in pregnant women younger than age 20, even after adjustment for smoking status. Cigarette smoking also appears to be a risk factor, when data from this and two previously published studies are combined. © 1993 Wiley‐Liss, Inc.
Developmental toxicity evaluation of diethyl and dimethyl phthalate in rats
Authors: Field Elizabeth A. , Price Catherine J. , Sleet Randolph B. , George Julia D. , Marr Melissa C. , Myers Christina B. , Schwetz Bernard A. , Morrissey Richard E.
Published: June 2005

Diethyl phthalate (DEP) and dimethyl phthalate (DMP), phthalic acid ester (PAE) plasticizers, were evaluated for developmental toxicity because of reports in the literature that some PAE were embryotoxic and teratogenic. A previous study (Singh et al., '72) suggested that an increased incidence of skeletal defects in rats might result from gestational exposure to DEP (0.6–1.9 g/kg) or DMP (0.4–1.3 g/kg), ip, on gestational days (gd) 5, 10, and 15. In the current study DEP (0, 0.25, 2.5, and 5%) or DMP (0, 0.25, 1, and 5%) in feed (approximately 0.2–4.0 g/kg/day) were supplied to timed‐mated rats from gd 6 to 15. Treatment with 5% DMP resulted in increased relative maternal liver weight. Also, animals exhibited reduced body weight gain during treatment (5% DEP or DMP) and during gestation (5% DEP). Weight gain corrected for gravid uterine weight was also reduced in animals fed 5% DEP. However, high‐dose treatment with either DEP or DMP resulted in changes in food and water consumption paralleling the body weight reductions, suggesting that apparent toxic effects on maternal body weight may reflect PAE/feed unpalatability. Treatment with 2.5% DEP resulted in only transient changes in body weight during early treatment. The only maternal effects at 0.25 or 1% DMP were minor changes in food and/or water consumption, and there were no effects at 0.25% DEP. Thus, the NOAELs for maternal toxicity were 1% DMP and 0.25% DEP. In contrast to the observed maternal toxicity, there was no effect of DEP or DMP treatment on any parameter of embryo/fetal development, except an increased incidence of supernumerary ribs (a variation) in the 5% DEP group. These results do not support the conclusion of other investigators that DEP and DMP are potent developmental toxicants. Rather, they suggest that the shortchain PAE are less developmentally toxic than PAE with more complex substitution groups, e.g., di(2‐ethylhexyl) phthalate, mono(2‐ethylhexyl) phthalate, and butyl benzyl phthalate. © 1993 Wiley‐Liss, Inc.
The effect of tolbutamide on rat embryonic development in vitro
Authors: Ziegler Marilyn H. , Grafton Thomas F. , Hansen Deborah K.
Published: June 2005

Tolbutamide (TOLB) is a sulfonylurea used to treat non‐insulin‐dependent diabetes mellitus and is a suspected teratogen. However, it is not possible to discriminate between potential teratogenic effects of TOLB and malformations produced by either drug‐induced hypoglycemia or the diabetic state itself. We examined the direct effect of TOLB on rat embryos cultured in a rodent whole embryo culture system. CD strain rat embryos were cultured for 48 h beginning on day 9 of gestation (plug day = day 0). Tolbutamide was added at various concentrations (90–3,600 μM). At the end of culture, viable embryos were examined for morphological score, number of somite pairs, crown‐rump and head lengths, and DNA and protein content. Tolbutamide produced doserelated decreases in all endpoints at concentrations (2,250–3,600 μM) which are two to four times the human therapeutic concentration. Sera from TOLB‐treated rats were adjusted to contain equal concentrations of glucose and insulin and then used for embryo culture. Serum from TOLB‐treated rats had no observable effect on embryonic development. The mechanism for the embryotoxic effect of TOLB is unknown; however, the drug was previously demonstrated to alter activity of purified yeast glutathione reductase (GR). Because GR may be important for normal embryonic development, the effect of TOLB on this enzyme activity in cultured rat embryos was evaluated. Tolbutamide (2,700 μM) reduced embryonic GR activity by 35–57%. These results indicate that TOLB has a direct embryotoxic effect at levels 2 to 4 times the usual therapeutic serum concentrations on developing rodent embryos which may be mediated by GR inhibition. © 1993 Wiley‐Liss, Inc.
Glucose causes lengthening of the microvilli of the neural plate of the rat embryo and produces a helical pattern on their surface
Authors: Shepard Thomas H. , Park Hyoung Woo , Pascoe‐Mason Julie
Published: June 2005

Prominent microvilli have been observed on the surface of neural plates in the embryos of many species. Since glucose is the main source of energy for embryos before neural tube closure and the onset of vascular circulation, it was of interest to study the relationship between these microvilli and glucose utilization in the neural plate. By applying microdrops of amniotic fluid to chemstrips, which colorimetrically measure glucose by glucose oxidase reaction, we determined that day 10 rat amniotic fluid glucose level was 31.6 ± 1.6 mg/dl. On day 10 and within about 20 min from removal of the decidual sites, no glucose was found in the amniotic fluid.

By use of a scanning electron microscope, the microvilli of the day 10 neural plate were found to have a 10‐fold increase in length during a 40‐min exposure to Hanks' solution at 21–23°C. Similarly exposed embryos in Hanks' without glucose did not have microvillus elongation. However, under whole embryo culture conditions at 38°C no extension of the microvilli was found. In the closed neural tube of the day 10 embryo, the microvilli were stubby and did not elongate with glucose exposure. Similarly, day 11 and 14 embryos had short microvilli which did not elongate with direct exposure to glucose at 21–23°C. The short microvilli on the surface of the closed neural tube on day 11, 14, and 16 were associated with low glucose concentrations in the neural tube fluids. By use of a field emission scanning electron microscope, the surfaces of the microvilli in the extended position were seen to be covered by a right‐handed helical array of globular objects the size of large molecules.

The findings support the hypothesis that microvillar length may modulate glucose uptake. Shortening is associated with low concentrations of glucose in closed neural tubes, and lengthening occurs at glucose exposures of 100 mg/dl. © 1993 Wiley‐Liss, Inc.
Tail short variable: Characterization of a new mouse mutant, and its possible analogy to certain human vascular disruption defects
Authors: Seller Mary J. , Wallace Margaret E.
Published: June 2005

A new mouse mutant, tail short variable (Tsv) produces a reduction deformity of the tail, growth retardation, and, in adults, a mild anemia. Genetic and embryological studies show that on all genetic backgrounds there is variable viability ofTsv/TsvandTsv/+ and phenotypic overlap within these and with +/+. A modifier is located to a short segment of chromosome 7, which alters the tail length ofTsv/+ mice up to 15%. The modifier,Tsv, and a coat texture mutant come from the same wild Peru mouse. The tail deformity is associated with, and may be caused by, a vascular disruption of the caudal aorta starting on day 11 of gestation. ThusTsvappears to be different from each of the thirty known mouse mutants involving the tail. It is suggested thatTsvcould be a mouse model for human conditions involving transverse terminal limb defects such as Moebius and de Lange syndromes. © 1993 Wiley‐Liss, Inc.