Congenital hydrocephalus in suckling hamsters caused by transplacental infection with parainfluenza virus type 3

The possible occurrence of congenital hydrocephalus by viral infection of the mother was examined by inoculating pregnant hamsters intravenously with parainfluenza virus type 3 (PIV-3). We could produce congenital hydrocephalus in littermates born to a mother which had been inoculated into the left cervical vein on the 14th day of pregnancy. This result may indicate that the virus could pass through the placenta to arrive at the fetus, and infect the central nervous system.

Embryotoxicity induced by alkylating agents: 6. DNA adduct formation induced by methylnitrosourea in mouse embryos

Formation of DNA adducts in 11-day-old mouse embryos was studied by measuring the initial alkylation rates of the methylated purine bases 7-methylguanine, O6-methylguanine, and 3-methyladenine. In the first part of the studies the adduct rates were measured in the teratogenic dose range (ED10-ED90, 2.7-5.6 mg/kg). These results were compared with similar data obtained from studies with ethylmethanesulfonate and acetoxymethyl-methylnitrosamine. For the three investigated substances a correlation was found between the initial adduct rate of O6-alkylguanine in the DNA of the embryos and the teratogenic potency. In the second part of the study the rate of adduct formation was measured in the sub-teratogenic dose range. These data will be used for molecular dosimetry in a risk assessment of low doses.

Extracellular matrix of the developing heart in normal and cardiac lethal mutant axolotls, Ambystoma mexicanum

As part of an ongoing study of heart development in normal and cardiac lethal mutant axolotls (Mexican salamanders) we examined the extracellular matrix (ECM) by microscopical methods. With scanning electron microscopy we are unable to detect ECM on the apical surface of cells of the early cardiogenic mesoderm. During the period of lateral plate migration, which coincides with the period of cardiogenic induction of mesoderm by anterior endoderm, there is little ECM, aside from some microfibrils, on the basal surface of the endoderm or mesoderm of the pharyngeal region. Later, a basal lamina (BL) is found on the endoderm and along portions of the developing endocardial and myocardial tubes. By the time of heartbeat initiation the BLs are complete and invested with striated collagen-like fibrils that are sparsely distributed in the "cardiac jelly" of normal and mutant hearts. Striated fibril deposition, which increases with time, is generally random in orientation, with the exception of some regions where there is a preferred directionality. During the post-hatching period striated fibrils appear in the subepicardial space. In addition, branching fibers that are probably elastin appear in the bulbus arteriosus. In these later stages the density of fibrils in the cardiac lethal mutant heart is much less than normal. Indirect immunofluorescent microscopy reveals laminin and fibronectin in the basal laminae of the endocardial and myocardial tubes of both normal and cardiac lethal mutant hearts. In addition, punctate and fibrillar staining for fibronectin, and punctate staining for laminin are found in the cardiac jelly. These matrix proteins are not abundant at the apical (exterior) surface of the myocardium until the epicardium appears.(ABSTRACT TRUNCATED AT 250 WORDS)

Penta X syndrome: a case report with review of the literature

We describe a 6 month-old girl with a 49, XX-XXX chromosome constitution. The patient had a characteristic round face, a low hairline, hypertelorism, epicanthus, a long philtrum, high-arched palate, short and webbed neck, small hands and feet, clinodactyly of the fifth fingers, overlapping toes, and separation between the first and the second toes. She also had atrial septal defect and patent ductus arteriosus complicated by myocarditis which exacerbated the course of her congestive heart failure. Psychomotor development was retarded with opisthotonoid posture, axial hypotonia, and with a borderline abnormal EEG. A densitometric, transmission analysis on X-linked polymorphic DNA-fragments of the Southern blots of the patient and the parents, using P20/MspI and pERT87-1/XmnI as probe/enzyme combinations, showed that the pentasomy X had resulted from 3 successive nondisjunctions at maternal meiosis. Clinical manifestations among 22 previously reported penta X syndrome patients are also reviewed.

A case of trisomy 21 with holoprosencephaly: the fifth case

A case of trisomy 21 with holoprosencephaly, the fifth case in the literature, is described. The patient also had extracephalic malformations frequently associated with Down syndrome. The possibility of a causal relationship between trisomy 21 and holoprosencephaly is discussed.

Refined determination of breakpoints of the translocation t(1;7) associated with signs of HMC syndrome

High-resolution band analysis was performed in order to precisely determine the breakpoints of a de novo chromosome translocation, t(1;7), which is associated with clinical signs of HMC syndrome (McKusick's #239800). The breakpoints were found to be at 1q31.2 and 7p15.1-p15.3, respectively. The finding of the translocation in this case might not be coincidental, but rather suggestive of the gene locus responsible for the development of HMC syndrome at either site of the breakpoints.

Species differences between rats and mice in the teratogenic action of ethylenethiourea: in vivo/in vitro tests and teratogenic activity of sera using an embryonic cell differentiation system

In vivo/in vitro studies on rats showed that ethylenethiourea inhibited the differentiation of midbrain cells more severely than that of limb bud cells. In in vitro studies using midbrain cell cultures, ethylenethiourea concentrations inhibited the production of differentiated foci by 50% in mouse cells, a rate 11-fold higher than that in rat cells. Differentiation of rat midbrain cells was also inhibited by the serum samples prepared from rats or mice dosed with up to 200 mg/kg of ethylenethiourea. However, differentiation of mouse cells was not inhibited by these animal serum samples. The concentration of ethylenethiourea in rat sera was only 2-fold higher than that in mice sera at 2 hr after dosing with 200 mg/kg. Therefore, the different sensitivity of the midbrains of these two species may be one reason that ethylenethiourea is teratogenic in rats but not in mice.

Effects of retinoic acid on embryonic development of mice in culture

The effects of all-trans-retinoic acid (RA) (tretinoin) on the craniofacial development of mouse embryos were examined using whole embryo culture. In day 8 embryos cultured for 48 h, embryonic growth was inhibited concentration-dependently by all-trans-RA treatment. Most of the treated embryos exhibited hypoplasia of the primary palatal processes and a reduction in the development of the first visceral arches. In day 10 embryos cultured for 48 h, although embryonic growth was not inhibited at any concentrations of all-trans-RA, median cleft lip (93%), hypoplasia of the primary palatal processes (37%) and limb reduction deformities (48%) occurred commonly. Furthermore, RA treatment greatly reduced the size of the secondary palatal processes. The incorporation of 3H-thymidine in the treated maxillary processes was decreased to 65% of the control value at 1.0 x 10(-7) M all-trans-RA. These findings indicate that all-trans-RA is teratogenic in mouse whole embryo culture.

Studies of variant palatal rugae in normal and corticosteroid-treated mouse embryos

Fourteen- and 15-day mouse embryos treated with triamcinolone on day 11 of gestation were examined for the presence of variant rugae. Nontreated mouse embryos served as controls. Variant rugae found were classified into five types. All five types of variations (bifurcation, division, supernumerary, shortness and cross) were observed in triamcinolone-treated embryos, and shortness was most frequently seen. Supernumerary, bifurcation and division were ranked next, following by cross. Variant, rugae, except the cross, were also observed in non-treated embryos in low frequencies, but more than one-half of them were the bifurcation of the second ruga. Divided rugae ranked next, and supernumerary and shortness were found occasionally. Except for the bifurcated and supernumerary rugae, the greater part of the variant rugae were found in the fifth and fourth ruga in the triamcinolone-treated groups and in the fifth ruga in the nontreated groups. As the incidence of variant rugae in the triamcinolone-treated embryos was significantly higher than that in the nontreated, it was regarded as one of the changes induced by the corticoid. Based on the characteristic features of the rugal region, it is speculated that the formation of variant rugae is associated with the disturbance of normal epithelial-mesenchymal interaction which may be controlled by the nerve fibers appearing at the time of rugal formation. The relationship between the increased appearance of variant rugae and the failure of palatal shelf elevation was examined, but no direct evidence was obtained.

Correction of microtia with construction of the tragus using a chondrocutaneous flap

For microtia correction we have been inserting a cartilage framework and reconstructing the tragus at the first operation in one stage, using part of the microtic ear. This procedure is started with transposition of the lower two-thirds of the microtic ear to make a lobule. The upper third of the microtic ear is elevated as a chondrocutaneous flap which is then transposed downwards to the conchal cavity to make a tragus. The cartilage of the chondrocutaneous flap is anchored, using a bolster to pull it back and outwards. Using this technique, we have reconstructed 34 microtic ears. Adequate positioning of the auricle and tragus has been achieved and a natural auricle obtained even when observed from a frontal oblique direction.

Comparative studies of embryotoxic action of ethylenethiourea in rat whole embryo and embryonic cell culture

The effects of ethylenethiourea (ETU) were investigated using rat (Wistar-imamichi) embryos cultured from days 11 to 13 of gestation or cultured rat embryonic cells extracted on day 11. Malformations in cultured embryos at the concentration of 30 micrograms/ml of ETU were found in the head and tail, which were severely affected, as well as the limb and face. All embryos exposed to 150 and 300 micrograms/ml of ETU had malformed heads, tails, limbs, and facial configurations. Protein contents of the cultured embryos were decreased dose-dependently at the concentrations ranging from 30 to 300 micrograms/ml. In the histological studies of the cultured embryos with ETU, thinner neuroepithelium in head was observed. In the embryonic cells extracted on day 11 of gestation, ETU dose-dependently inhibited the differentiation of midbrain (MB) cells into neurons and that of limb bud (LB) cells into chondrocytes at the concentrations ranging from 30 to 600 micrograms/ml of ETU. The concentrations of ETU that inhibited the production of differentiated foci by 50% (IC50) were 170 micrograms/ml in LB cells of day 11, and greater than 600 micrograms/ml in LB cells on day 12 of development. Therefore, differentiation of MB cells was more sensitive to ETU than the differentiation of LB cells. These results indicated that there was a reasonable correlation of ETU induced changes in cultured whole embryos and embryonic cells.

New metabolites of thiabendazole and the metabolism of thiabendazole by mouse embryo in vivo and in vitro

Thiabendazole [2-(4'-thiazolyl)benzimidazole; TBZ], a teratogen in ICR mice, is known to be mainly metabolized to 5-hydroxy-TBZ (5-OH-TBZ) and its conjugates in domestic and laboratory animals. Besides the known metabolites of TBZ, 4-hydroxy-TBZ and 2-acetylbenzimidazole (ABI) were identified as new metabolites of TBZ in the urine of F344 rats and ICR mice. 5-OH-TBZ and ABI, as well as TBZ, were found in the embryos of ICR mice given TBZ orally on day 10 of gestation. In the whole-embryo culture system, 5-OH-TBZ and ABI in the medium, and TBZ, 5-OH-TBZ and ABI in the embryo were detected after 24 hr of culture in 25 or 50 micrograms TBZ ml. However, the amount of metabolites in the embryo in vitro was very small compared with that detected in vivo, whereas the amount of TBZ was comparable. Furthermore, the mouse embryo homogenate, at organogenesis, metabolized TBZ to 5-OH-TBZ or ABI. The specific activity required by this homogenate to form 5-OH-TBZ or ABI was less than 1/1000 of that of the liver microsomal fraction. The results suggested that mouse embryos at organogenesis could metabolize TBZ, although most of the metabolites in the embryo in vivo came from the dam.

Abnormal development of cardiovascular systems in rat embryos treated with bisdiamine

Administration of N,N'-bis(dichloroacetyl)-1,8-octamethylenediamine, bisdiamine, in pregnant Donryu rats on day 10 of gestation induces a high incidence of cardiovascular anomalies in fetuses. Bisdiamine administration induced aplasia of the sixth aortic arch artery, with both the right and left primitive pulmonary arteries being directly linked to the truncus, and resulting in four types of malformation of pulmonary arteries (PAs). When two primitive PAs shared a single root, the consequence was either pulmonary trunk hypoplasia, as is seen in tetralogy of Fallot, or type I persistent truncus arteriosus (PTA) as classified by Collet and Edwards. When root portions of two PAs did not fuse, either type II or type III PTA resulted. In controls, the right dorsal aorta (DA) between the right seventh intersegmental artery (IA) and the site where both DAs fuse degenerated and the left aortic arch (AA) and the right subclavian artery (SA) were formed. Bisdiamine administration induced two additional types of vascular anomalies. In one of these, the right DA between the right 4AA and the right 7IA degenerated and a left AA accompanied by an aberrant right SA resulted. In the other type, the left DA between the left 4AA and the left 7IA degenerated and a right AA accompanied by an aberrant left SA resulted. These results indicate that administration of bisdiamine induces malformation in the great blood vessels by disturbing persistency and degeneration of aortic arch arteries and DAs.

Activity profiles of developmental toxicity: design considerations and pilot implementation

The available literature was searched for quantitative test results from both in vitro and in vivo assays for developmental toxicity for five model compounds: cyclophosphamide, methotrexate, hydroxyurea, caffeine, and ethylenethiourea. These compounds were chosen on the basis of their extensive utilization in a variety of assay systems for developmental toxicity as evidenced by their representation in the ETIC database (each generally has 100-500 citations encompassing multiple test systems). Nine cellular-based assays, six assays using whole embryos in culture, as well as Segment II and abbreviated exposure tests for mammalian test species are included in the database. For each assay, the critical endpoints were identified, each of which was then provided a three-letter code, and the criteria for extraction of quantitative information were established. The extracted information was placed into a computerized reference file and subsequently plotted such that the qualitative (positive/negative) and quantitative (e.g., IC50, highest ineffective dose (HID), lowest effective dose (LED] results across all test systems could be displayed. The information contained in these profiles can be used to compare qualitative and quantitative results across multiple assay systems, to identify data gaps in the literature, to evaluate the concordance of the assays, to calculate relative potencies, and to examine structure-activity relationships.

When should we expect prenatally damaged human brains to have abnormal neuronal connections?

Abnormal function in prenatally damaged brains may occur as the result of loss of neuronal an/or glial elements, abnormal morphology of neurons, or abnormal and inappropriate connections. By abnormal connection I mean projections from a given nucleus to a nucleus or cortical region in the brain which does not normally receive such a projection. In the present paper it is proposed that focal brain damage, i.e. that damage involving circumscribed regions of the developing brain on one side of the body, is more likely to induce abnormal connections, than diffuse brain damage, affecting most of the brain bilaterally. This proposition is based on the available evidence from animal studies, albeit scanty, and is presented as a working hypothesis for future studies of human congenital brain damage.

Embryolethality of new herbicides is not detected by the micromass teratogen tests

New herbicidal compounds (11 pyrimidine-diones, 3 benzoates and 1 sulfonamide) were found to be embryolethal but not teratogenic in rats. The range of the embryolethal dose varied from 0.2 to greater than 200 mg/kg. This broad range enabled us to validate whether proposed in vitro teratogen tests can detect the embryolethality of these herbicides. The IC50 values (inhibition concentration 50%) for both differentiation and proliferation of midbrain and limb bud cells of rat embryos were determined and found to be above 50 micrograms/ml in all cases, confirming that the herbicides were not teratogenic. No correlation, however, was observed between the embryolethality in vivo and the activities in these cells. In order to test whether the potential to cause embryolethality could be predicted and detected as a general cytotoxic effect, the inhibition of colony forming ability in V79 cells was determined. The results indicated that cytotoxicity in V79 cells may be useful for preliminary testing of the embryolethal effect of herbicides.

Reproductive toxicity and toxicokinetics of 2,3,7,8-tetrachlorodibenzo-p-dioxin. 2. Problem of paternally-mediated abnormalities in the progeny of rat

Possible effects on the next generation after long-term exposure (subcutaneous administration) of male rats to very high doses of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) were studied. Two dose regimes were applied: TCDD-25 (initial dose: 25 micrograms/kg body wt; maintenance dose: 5 micrograms/kg body wt, once weekly) and TCDD-75 (initial dose: 75 micrograms/kg body wt; maintenance dose: 15 micrograms/kg body wt). Male rats were treated for 10 weeks before mating and then throughout the entire 12 week mating period. They were mated to unexposed virgin females. One group of pregnant females was used for teratological evaluations, and another group was allowed to deliver. No significant differences were observed in the number of implantations or fetuses per litter, and resorption rate, and fetal weight between the controls and TCDD-treated groups. No gross-structural anomalies occurred in any of the fetuses sired by TCDD-treated males. In the TCDD-25 group an increased frequency of two types of variations was observed which also occur in controls: incompletely ossified fingers (TCDD-25 = 5.1%, controls = 2.6%), and incompletely ossified ossa zygomatica (TCDD-25 = 1.8%, controls = 0.5%). In the TCDD-25 group a slight but statistically significant increase was observed in the rate of stillbirths (TCDD-25 = 1.3%, controls = 0.1%), apparently due to an unusually low frequency occurring in the controls (overall historical controls = 0.6%). There was no difference in postnatal mortality (TCDD-25 = 1.3%, controls = 1.3%). Taken together, despite the very high doses of TCDD used, the data do not provide evidence for biologically significant paternally-mediated developmental toxicity in the fetuses and newborn.

Whole embryo culture: interpretation of abnormal development in vitro

An overview will be given of a number of problems that arise when we attempt an interpretation of data obtained with the whole embryo culture method (WEC). The following aspects will be considered: 1) Types of deviation from normal development in the whole-embryo culture system: (a) problem of "artifacts" (for example, due to preparation mistakes and suboptimal culture conditions), (b) types and frequency of abnormal development in controls, retardation as an abnormal outcome, and the difficulty of assessing its significance, (c) gross-structural defects and, specifically, attempts to answer the following questions: (i) What are the limitations for an assessment of abnormal development with the WEC? (ii) Is a specific abnormality pattern recognizable under specific pathologic conditions? (iii) Is the rate of induced abnormal development concentration-dependent? (2) Problems encountered when interpreting concentration-effect relationships (for example, statistical and pharmacokinetic aspects). (3) Necessity of verifying in vitro effects with in vivo studies.

A histological and histochemical study on glycosaminoglycans in epiphysial cartilage of osteochondrodysplasia rat (OCD/OCD)

The osteochondrodysplasia rat, inherited by a single autosomal recessive lethal gene ocd, shows a typical dwarfing syndrome with systemic subcutaneous edema. The skeletal system is most severely affected. The affected neonates are associated with cleft palate, abnormal kidney position and central nerve system malfunction. The present study describes histological and histochemical appearances of the affected epiphysial cartilage. Irregular columnization, thinner hypertrophic zone, swelled chondrocytes, tightly packed chondrocytes with a poor amount of cartilage matrix was found in the affected. The defining characteristic was a wide-spread degenerating area from the resting to hypertrophic zone. The extracellular matrix (ECM) reacted weakly for the glycosaminoglycans (GAGs). A reduced content of sialic acid in the ECM was suggested. It is concluded that the cartilage abnormalities in the ocd/ocd is a new type disease of osteochondrodysplasia possibly due to some defects in GAGs and/or sialic acid metabolism.

Induction of fetal malformations after treatment of mouse embryos with methylnitrosourea at the preimplantation stages

The effects of methylnitrosourea (MNU) on the development of preimplantation mouse embryos were investigated in this study. ICR mice were treated intraperitoneally with single doses of 10, 20, and 30 mg MNU/kg body wt on day 0, 1, 2, or 3 of pregnancy. The uterine contents were examined on day 18 of pregnancy. The fetuses were examined for external and skeletal abnormalities. No significant differences were observed in the number of implantation sites between all the MNU-treated groups and controls. MNU treatment on day 2 or 3 of pregnancy caused dose-dependent significant increases in the incidence of abnormal fetuses over the control level, while treatment on day 0 or 1 failed to cause an increase of abnormalities. Cleft palate, exencephalus, and malformed vertebrae were the most common types of abnormalities. In the embryo transfer experiments, the frequency of fetal abnormalities induced when embryos were transferred from MNU-treated females to untreated pseudopregnant females was significantly higher than that induced when embryos were transferred from untreated females to MNU-treated or untreated pseudopregnant females. The results in the present study confirm and extend the previously proposed hypothesis that the direct effects of MNU on preimplantation embryos make a significant contribution to the induction of fetal malformations.

Electron microscopic observations and electrophoresis of the glycosaminoglycans in the epiphyseal cartilage of the congenital osteochondrodysplasia rat (ocd/ocd)

The osteochondrodysplasia rat, inherited by a single autosomal recessive lethal gene ocd, shows a typical dwarfing syndrome with systemic subcutaneous edema. The skeletal system is most severely affected. The affected newborn also demonstrates abnormal kidney position and respiratory system anomalies and central nervous malfunction. Previous light microscopic observations show that the chondrocytes are expanded and destroyed, and the amounts of extracellular matrix (ECM) and glycosaminoglycans (GAGs) are decreased. The present studies describe ultrastructural appearances, and measurement and electrophoretic analysis of the major components of the cartilaginous GAGs. Decrease in amounts of ECM and swollen chondrocytes with the expanded organelles were reconfirmed in the ocd/ocd by electron microscopic observation. The large expanded vesicles contained unevenly distributed granular materials and large ruthenium red (RR) granules. The RR granules in the ECM were small and most parts of the collagen fibers did not associate with the granule in the ocd/ocd, while the RR granules attached to all the collagen fibers in the phenotypically normal (+/?). There were large collagen bundles in the region where the chondrocytes were committed to self-destruction. The biochemical analysis of the cartilage showed that noncollagenous proteins were increased and the GAGs were decreased in amount in the ocd/ocd, although the hydroxyproline content was comparable to that of the +/?. The hyaluronic acid was close to the limit of detection by electrophoresis of the cartilaginous GAGs in the ocd/ocd. These results suggest that the ocd gene affects GAG metabolism. The decrease in amounts of GAGs, especially hyaluronic acid, may be responsible for the anomalies of the cartilage in the ocd/ocd.

Teratogenicity of arotinoids (retinoids) in vivo and in vitro

The effect of structural modifications on the arotinoid molecule, a new class of retinoids, on their teratogenicity in mice was studied. Animals were treated on days 8 and 9 of gestation, the most susceptible stages to retinoid-induced malformations in rodents. The teratogenic potency of the 13 arotinoids tested varied over a dose range of more than five orders of magnitude. Next, we tested whether the quantitative differences in the teratogenicity of these arotinoids correlates with their activity in high density (micromass) cultures of rat embryonic limb bud and midbrain cells. There was a good quantitative correlation between the in vivo teratogenicity and the in vitro activity in limb bud cells but no correlation was found in midbrain cells. Thus, the limb bud cell culture system may be useful for a preliminary testing to select non-teratogenic retinoids. For the risk assessment in humans, however, the in vitro results should be verified in animals studies.

Genetic control of the survival of murine trisomy 16 fetuses

A mouse model that allows for the experimental induction of an aneuploid state has been employed to investigate the factors that control the survival of trisomy 16 fetuses. The prevalence of trisomy 16 fetuses on day 15 of gestation was shown to vary significantly with the genetic background of the female parent. The ability to spontaneously abort a trisomy 16 conceptus was shown to be higher in the mouse strain with a low prevalence of trisomy 16, compared to those mouse strains with a high prevalence of trisomy 16. Furthermore, the maternal ability that selects against, or promotes the survival of a trisomic conceptus was shown to be specific for the trisomy in question.

The teratogenic effects of E-64 on rat embryogenesis

To examine the effects of E-64 (a thiol protease inhibitor) on the development of rat embryos, pregnant Wistar rats were injected with 10-30 mg/kg of E-64 intra-peritoneally on days 9 and 10 of gestation. On day 21, the rats were killed and the fetuses were examined for malformations. When 30 mg/kg of E-64 was administered, the incidence of resorptions and malformations was 25.7% and 60.4%, respectively. The most common malformations were hydrocephaly, exencephaly, anophthalmia, microphthalmia, hydronephrosis and renal hypoplasia. These results suggest that thiol protease inhibitor is teratogenic during early rat embryogenesis.

Evaluation of the teratogenic potential of the plasticizer butyl benzyl phthalate in rats

The teratogenicity of butyl benzyl phthalate (BBP) was studied in Wistar rats. Pregnant rats were given BBP at a dosage of 0, 0.25, 0.5, 1.0 or 2.0% in the diet from day 0 to day 20 of pregnancy. Daily intakes of BBP were 185 mg kg-1 for the 0.25% group, 375 mg kg-1 for the 0.5% group, 654 mg kg-1 for the 1.0% group and 974 mg kg-1 for the 2.0% group. Adjusted maternal body weight gain (body weight gain excluding the gravid uterus) during pregnancy in the 1.0 and 2.0% groups was significantly lowered. Food consumption during pregnancy in the 0.25 and 0.5% groups did not differ from that in the control group. No death was noted in the pregnant females of any group. There was no significant compound-related effects on the incidence of preimplantation loss. All dams given 2.0% BBP exhibited complete resorption of all the implanted embryos. Morphological examinations of the fetuses revealed no evidence of teratogenesis. It could be concluded that the no-observable-effect-levels (NOEL) in rats were 0.5 and 1.0% BBP in the diet for maternal and embryofetal toxicity, respectively.

Examination of the eyelid closure defect in trisomy 16 mice

A characteristic feature of trisomy 16 mouse conceptuses is a failure of their eyelids to close. This defect was investigated by examining ocular development in serially sectioned heads of trisomy 16 and normal littermate fetuses from 10 to 18 gestational days. Other heads were examined by using scanning electron microscopy. Between 10 and 15 days, trisomy 16 ocular structures were delayed, but there was no striking abnormal morphology. At 16 days, when the eyelids were closed and fused in normal mice, trisomic eyes had a large cell mass near the inner canthus that protruded between the open lids. The mass was covered by bulbar conjunctiva and cells of the mass were continuous with developing corneal tissue. The mass was not present in the eyes of normal mice on any gestational day and was not present in trisomic eyes at 17 and 18 days, when the lids began to show varying degrees of closure. Based on its positioning at the inner canthus, the mass may represent a transient hyperplasia of the developing semilunar fold which physically impedes lid closure in the trisomic conceptuses. Previously, the defect has been attributed to the trisomy 16 conceptus's overall pattern of growth retardation and delayed development. Masses such as those seen in the trisomic eyes have not been observed in other murine lid-gap defects that have been investigated. A second finding in this study is that trisomic eyes are positioned more superiorly in the head than normal eyes. This variation may be related to alterations in cranial base morphology that are associated with trisomy 16.

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

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.

Fraser syndrome with renal agenesis in two consanguineous Turkish families

We report on 3 girls and one boy from 2 sibships with Fraser syndrome and renal agenesis. They were born to consanguineous parents, which supports an autosomal recessive mode of inheritance.

Fetal deaths with birth defects among Japanese multiples, 1974

Source of data is "Survey on Socio-Economic Aspects of Vital Events-Plural Births in 1975", including 12,392 twin pairs, 124 triplet sets, 7 quadruplet sets and 1 quintuplet set. Fetal deaths were 3,285 for twins, 141 for triplets, 17 for quadruplets, and 5 for quintuplets, among which the number of birth defects were 78, 3, 0, and 0 respectively. Concordant twin pairs with the same category of birth defect were 20 among 56 pairs (0.36). As for the remaining 36 pairs, 2 pairs had different category of birth defects, 27 pairs had liveborn cotwins, and 7 pairs were both fetal deaths among which a twin had birth defect. The second-born twins had birth defects more frequently than the first-born twins among fetal deaths (28 vs 6).

Fetal laser surgery in genetic polydactyly mice

The first digital ray of the hindlimb plate in Slc:ICR mouse fetus was irradiated with 2 watts argon laser beam for 0.3 sec after releasing from the abdominal cavity and envelop of uterine myometrium on day 13 of gestation, and then the fetuses were allowed to develop in the abdominal cavity contacting with the uterus via the placenta exo utero until term. ICR mouse fetuses which received fetal laser surgery lost their first digits completely, resulting in 4-digit hindfoot on day 18 of gestation. The homozygous Polydactyly Nagoya (Pdn/Pdn) mice exhibit 1-3 extra digits both in the fore- and hindlimbs preaxially. The extra digital rays in the left hindlimbs of Pdn/Pdn fetuses were irradiated with 2 watts argon laser beam for 0.3 sec on day 13 of gestation exo utero. The left hindlimbs of the Pdn/Pdn fetuses which received fetal laser surgery lost their preaxial extra digits on day 18 of gestation, resulting in 5 digits, though their 1st digit was triphalangia. The combination of a laser instrument with the fetoscope and/or ultrasound scanner may promote the fetal surgery of congenital anomalies in humans.

Bleomycin-induced chromosomal damage in tuberous sclerosis

To investigate the possible involvement of mutagen-induced chromosomal instability in tuberous sclerosis the blood lymphocytes obtained from eleven patients with this disease and eleven healthy controls of comparable age and sex were exposed to bleomycin in vitro during the late S and G2 phases of the cell cycle. Neither the spontaneous aberration yields nor the bleomycin-induced chromosomal sensitivity differed between the two groups. The chromosomal distribution of 578 and 478 induced breaks in patients and controls, respectively, was similar. Thus, bleomycin-induced G2 chromosomal hypersensitivity in lymphocytes of patients with tuberous sclerosis is not an intrinsic feature of this hereditary disease.

Effects of phorone and/or buthionine sulfoximine on teratogenicity of 5-fluorouracil in mice

Embryotoxicity and teratogenicity of 5-fluorouracil (5-FU) and modulation of its effect by the depletors of glutathione (GSH) were evaluated in mice. Pregnant ICR mice were intraperitoneally (i.p.) injected with 25 mg/kg of 5-FU on day 11 of gestation (vaginal plug = day 0). Mice were pretreated i.p. with 250 mg/kg of phorone, a GSH depleting agent and/or 200 mg/kg of buthionine sulfoximine (BSO, an inhibitor of GSH biosynthesis) 4 hours before dosing with 5-FU. Dams were killed on day 17 of gestation. Fetuses were examined for external malformations, especially limb malformations. Pretreatment with phorone or BSO decreased fetal weight and increased the frequency and severity of oligodactyly induced by 5-FU, as well as the reduction of maternal GSH levels. Combined use of 125 mg/kg phorone and 100 mg/kg BSO i.p. augmented growth retardation induced with 5-FU. Cotreatment with exogenous GSH, at a dose of 300 mg/kg injected intravenously, could not suppress the augmentative effects of phorone and/or BSO on 5-FU teratogenicity under these experimental conditions. These results indicate that the level of endogenous GSH is one of the factors which significantly affects teratogenicity of 5-FU.

Maternal-fetal electrocardiographic effects and pharmacokinetics after an acute i.v. administration of caffeine to the pregnant rat

The relationship between fetal exposure and cardiovascular functional effects in the caffeine-treated pregnant rat was investigated. Caffeine (100 mg/kg) was administered intravenously to dams on day 21 of gestation. The transplacental transport of caffeine was studied by obtaining maternal and fetal blood (umbilical vein) samples at designated times after drug administration. Concurrent maternal-fetal electrocardiograms (ECGs) were measured and evaluated for caffeine-induced changes. Maternal and fetal plasma caffeine levels as well as area under the curve values were proportionally related throughout the experiment, indicative of equal exposure to caffeine. The fetal ECG exhibited more extensive changes associated with caffeine than did the dam's, but the effects were not detected in the first 30 min, suggesting a lag period for the action of caffeine on the fetal heart. The frequency of fetal ectopic beats and abnormal T waves were directly related to fetal plasma caffeine levels. Fetal ECG combined with the fetal blood microsampling technique was a practical method of testing for prefunctional effects of caffeine in the rat fetus.

Congenital malformations in rats with the semilethal mutation fused pulmonary lobes

It has been demonstrated that an autosomal recessive gene, fused pulmonary lobes (fpl), causes fusion of the right pulmonary lobes with several associated malformations and a high incidence of death in homozygous newborns (Aoyama et al. Teratology 1988; 37:159-166). The aim of the present study was to investigate whether the deaths of fpl/fpl newborns were caused by functional abnormalities of the malformed lung or other associated malformations. Day-20 fpl/fpl and fpl/+ fetuses were weighed and examined for gross abnormalities. The lungs of selected fetuses were further examined for histological abnormalities. A wide variety of associated external, visceral, and skeletal anomalies as well as relatively lower body weights than those of phenotypically normal fpl/+ littermates were observed in the fpl/fpl fetuses. The associated anomalies consisted of hematomas and/or subcutaneous hemorrhages in the head, truncus and limbs, eyelid anomalies, CNS defects, lobation anomalies of the liver, hypoplasia of the spleen, partial absence of the skull bones, and dorsi- or ventriflexion of the phalanges of the limbs. Among them, CNS defects and partial absence of the skull bones were considered to be possible causes of newborn deaths. However, the incidence of these malformations was approximately 10% and was lower than the neonatal mortality, which had been estimated to be approximately 50% in the previous study (Aoyama et al. Teratology 1988; 37:159-166). The lungs of fpl/fpl fetuses consistently had hypoplasia of the intermediate lobe and fusion of the right pulmonary lobes. No histological changes suggesting postnatal respiratory insufficiency were found in the lungs of day-20 fpl/fpl fetuses, and the cause of newborn death remains unclear.

Structural and neurochemical effects in mouse cerebellum following neonatal methylazoxymethanol and 6-hydroxydopamine treatment

The effects of neonatal treatment with the antimitotic agent methylazoxymethanol and the catecholamine neurotoxin 6-hydroxydopamine on cerebellar morphology and monoamine innervation in the N.M.R.I. mouse has been studied. Methylazoxymethanol (25 mg/kg s.c.) treatment induced a cerebellar weight reduction of 40% as observed in the adult stage, while other CNS regions analysed were unaffected. An obvious atrophy of the cerebellar cortex was found, with an irregular distribution of the Purkinje cells, while Bergmann glia fibers deviated from their normal radial configuration and showed a tendency to form clusters. A 65% increase of tyrosine hydroxylase immunoreactive fiber density was found in the cerebellar cortex and 3H-5-hydroxytryptamine in vitro synaptosomal uptake was increased by 55%. Noradrenaline and 5-hydroxytryptamine concentrations in the cerebellum increased by 50 and 30%, respectively, whereas the total content of both neurotransmitters in cerebellum was approximately unchanged after methylazoxymethanol treatment. A significant reduction in total cerebellar in vitro binding of 3H-WB-4101 and 3H-dihydroalprenolol was also found, indicating compensatory receptor alterations following methylazoxymethanol treatment. The effect of combined treatment of methylazoxymethanol and the neurotoxin 6-hydroxydopamine (50 mg/kg s.c., day 1) showed a very pronounced reduction of noradrenaline concentration in cortex cerebri, while the noradrenaline concentration in cerebellum was increased by 185% and the tyrosine hydroxylase immunoreactive fiber density by 125%, indicating an additional relative hyperinnervation of cerebellar noradrenaline fiber due to a "pruning effect" of the 6-hydroxydopamine treatment. The results imply a relatively rigid development of terminal arborization of central nervous system monoamine neurons, relatively independent of neuronal and glial arrangement in the target area.

Transport of amino acids by the human placenta: predicted effects thereon of maternal hyperphenylalaninaemia

Brush border and basal plasma membrane vesicles prepared from normal term human placental syncytiotrophoblast have been used to study amino acid transport. Such studies are reviewed and novel results presented which confirm that saturation of placental transport by phenylalanine is unlikely to limit delivery of this amino acid to the fetus even with grossly raised maternal concentrations. Such raised maternal levels of phenylalanine are, however, likely to severely embarrass the delivery to the fetus across the placental brush border membrane of L-tyrosine and, to a lesser extent, of L-tryptophan. Reasons for thinking that this may be relevant to the fetal damage found in maternal PKU are discussed.

Developmental and aging changes in the expression patterns of beta-amyloid in the brains of normal and Down syndrome cases

Immunohistochemical staining with polyclonal antibodies to synthetic amyloid (residues 1-28 of A4) was performed on normal and Down syndrome brains from fetuses to adults. Positive staining appeared in the cytoplasmic processes of astrocytes in the subpial layer and white matter of developing brains, and reappeared in astrocytic fibers of the subpial layer as well as in cerebrovascular and plaque core amyloid in elderly brains. The reappearance of positively stained astrocytes and amyloid occurred earlier in adult Down syndrome patients. The results indicate that the A4 protein is a developmental protein, and its reappearance in Alzheimer and adult Down syndrome brains may be related to the regeneration process.

Evaluation of the teratogenic potential of the rubber accelerator dibenzthiazyl disulphide in rats

The teratogenic potential of dibenzthiazyl disulphide (MBTS) was studied in Wistar rats. Pregnant rats were given MBTS at a dosage of 0, 0.04, 0.2 or 1% in the diet from day 0 to day 20 of pregnancy. Daily intakes of MBTS were 26 mg kg-1 for the 0.04% group, 127 mg kg-1 for the 0.2% group and 596 mg kg-1 for the 1% group. Maternal body weight gain during day 0 to day 14 of pregnancy in the 1% group was significantly lowered, but no significant changes induced by MBTS were observed in any other maternal parameters, such as food consumption and clinical sign of toxicity. There were no significant compound-related effects on the incidences of pre- and postimplantation losses and the number, sex ratio and body weight of live fetuses. Morphological examinations of the fetuses revealed no evidence of teratogenesis. In the postnatal development of the offspring from the dams given MBTS, a high survival rate and good growth of the offspring were seen. It could be concluded that MBTS possesses no adverse effects on the pre- and postnatal development of the offspring in rats at the doses employed in the present study.

Significance of cardiovascular malformations in cystic hygroma: a new interpretation of the pathogenesis

Fetuses with cystic hygroma or loose skin of the neck were studied chromosomally and phenotypically to clarify the relation between neck abnormality and cardiovascular malformations. Of 12 fetuses, 9 had chromosome abnormalities: 4 with 45,X, 3 with trisomy 21, one each with trisomy 13, dup 6q. One had normal chromosomes. Two cases, in which chromosome analysis was unsuccessful, were morphologically suspected to be trisomy 13. Nine of the 12 fetuses had either bilateral cystic hygroma of the neck (7 cases) or nuchal bleb (2 cases: trisomy 13 and dup 6q). Two of the 3 remaining cases (trisomy 21) had loose skin of the neck, and one had edematous swelling of the skin of the neck. Except for the last case of trisomy 21, 11 fetuses (91.7%) had severe and/or rare cardiovascular malformations. They were divided into 3 major groups: a) spectrum of hypoplastic left heart syndrome (45,X and dup 6q), b) double outlet right ventricle, agenesis of semilunar valve (trisomy 13), and c) abnormality of atrioventricular orifice or valves (trisomy 21). One fetus with normal chromosomes had persistent left superior vena cava instead of absent right one and calcification of myocardium. Histological observation of edematous skin demonstrated the abnormal distribution of lymph vessels, including their absence. Some cases showed hypoplastic thymus. To integrate the findings of the present study and the descriptions in the literature, a pathogenesis is hypothesized in relation to migration of neural crest cells and extracellular matrix.

Developmental toxicity of isomalt in rats

The sugar replacer isomalt, a 1:1 mixture of the disaccharides glucopyranosylsorbitol and glucopyranosylmannitol, was incorporated in the diet of rats. Female Bay FB:30 rats were adapted to isomalt by feeding them a diet containing a gradually increasing amount of isomalt for several days, prior to mating. Subsequently, they were mated. Isomalt was fed continuously in concentrations of 2.5, 5 and 10% up to day 20 of pregnancy. In addition, one group of female Wistar rats was mated and fed 10% isomalt incorporated in the diet from day 0 up to day 20 of pregnancy, without previous adaptation to isomalt. Finally, one group of untreated female Wistar rats served as controls. Half of the number of females in each group was selected for caesarian section on day 20 of pregnancy. The other half was allowed to litter and rear their pups for 2 weeks (Wistar rats) or 3 weeks (Bay FB:30 rats). In the females of the Bay FB:30 rats, a decreased body-weight gain and food consumption were observed in the 5 and 10% isomalt group. Minor retardation in the development of the foetuses was observed in the 10% isomalt group only with the Bay FB:30 rats and was therefore considered to be related to maternal toxicity. In addition, a dose-related increase in the incidence of wavy ribs occurred in foetuses of the Bay FB:30 rats. However, none of the observed effects were persistent in neonates. Isomalt appeared to have slight toxic effects in the dams of the Bay FB:30 strain but no toxicity in the offspring. In Wistar rats no toxicity and no effects on maternal performance or on embryonic, foetal or neonatal development were seen. Isomalt, when fed at dietary levels up to 10%, did not induce structural or functional teratogenic effects in rats of either the Wistar or the Bay FB:30 strain.

Behavioral teratogenic effect of methylmercury and d-amphetamine: meta-analysis and power analysis of data from the Collaborative Behavioral Teratology Study of National Center for Toxicological Research

The data of the Collaborative Behavioral Teratology Study (CBTS) were analyzed. Population-effect sizes were estimated, in terms of confidence intervals, by meta-analysis. A treatment effect of methylmercury was clearly observed and a dose-response effect was also observed. On the other hand, no clear treatment effect was observed in the d-amphetamine study. The effect of auditory startle habituation was very large, although it was limited to the high-dose group in the methylmercury study. The effects observed for physical landmarks were, as a whole, somewhat larger than those for behavioral measures. There is no clear evidence for sex-related differences except for activity measures. A curious treatment effect that was not referred to in the CBTS report was observed: eye-opening day and incisor-eruption day were hastened by the treatment of methylmercury. Power analysis results showed that obtaining a statistically significant effect for these compounds is very difficult, suggesting that even though published papers reported the significant effect of these compounds there might have been many unpublished experiments that obtained nonsignificant effects. If one uses these compounds as positive controls, a very large sample size will be needed. No highly sensitive test that is reproducible across compounds or dose-levels was observed among tests employed in the CBTS.

Sulfated proteoglycans synthesized by Neuro 2a neuroblastoma cells: comparison between cells with and without ganglioside-induced neurites

Mouse neuroblastoma Neuro 2a cells are known to extend neurite-like processes in response to gangliosides added to the culture medium. We compared the structural features of proteoglycans (PG) synthesized by conventional Neuro 2a cells with those of neurite-bearing cells. Two different proteoglycans labeled with [35S]sulfate, namely, chondroitin sulfate proteoglycan (CS-PG) and heparan sulfate proteoglycan (HS-PG), were found both in the cell layer and in the culture medium of the conventional cells. CS-PG isolated from the cell layer had a Kav value of 0.38 on Sepharose CL-6B, and had CS side chains with Mr of 27,000. HS-PG in the cell layer was slightly larger (Kav of 0.33) in terms of hydrodynamic size than CS-PG, and the apparent Mr of the heparan sulfate side chains was 10,000. The structural parameters of CS-PG and HS-PG isolated from the medium were almost identical to those of the PGs in the cell layer. In addition to these PGs, single-chain HS, with an average Mr of 2,500, was observed only in the cell layer and this component was the major sulfated component in the cell layers of both control and ganglioside treated cells. The neurite-bearing cells also synthesized both CS-PG and HS-PG which were very similar in hydrodynamic size to those synthesized by the conventional cells, but the size of HS side chains was greater. Radioactivity, as 35S, of each sulfated component from the ganglioside-treated culture seemed to be slightly less than that of the corresponding component from the control culture. These findings indicate that the marked morphological change in Neuro 2a cells, induced by gangliosides is not accompanied by major changes in the synthesis of PGs.

First trimester prenatal diagnosis of haemophilia A using factor VIII gene probe

Accurate first-trimester prenatal diagnosis was achieved in a Japanese haemophilia A family by the use of a restriction fragment length polymorphism (RFLP) located within the F.VIII gene. Since the pregnant woman's heterozygosity for BclI polymorphism in F.VIII/intron 18 (F8A) probe was informative, chorionic villus sampling (CVS) was performed at 9 weeks of gestation. Restriction analysis showed that the fetus was heterozygous for the BclI site and had received a normal paternal X chromosome (0.9 kb) and a normal maternal X (1.2 kb). Therefore, we concluded that the fetus was a non-carrier female. Pregnancy went to term and woman gave birth to an apparently healthy female. At one week after birth a coagulation study confirmed that the newborn infant is not a carrier. The first-trimester prenatal diagnosis of haemophilia A is possible by CVS due to a RFLP in the F.VIII gene.

Behavioral teratogenic insult of methylmercury assessed by using sets of measures: reanalysis of data from the Collaborative Behavioral Teratology Study of National Center for Toxicological Research

The data of the Collaborative Behavioral Teratology Study were analyzed by using sets of measures simultaneously. A set of preweaning measures offered far more information as to treatment effects than a set of postweaning measures. The treatment effect observed in behavioral measures was also explained considerably by physical measures. However, the effect explained by uniquely behavioral measures (i.e., magnitude of semipartial R2) was also observed in some degree. A sex-related difference was observed in auditory startle response habituation appearing only later or earlier in life. The usefulness of using a set of measures and assessing the relationship among sets in behavioral teratology, in addition to conventional single measure analysis, was discussed.

Evaluation of the teratogenic potential of the rubber accelerator N-cyclohexyl-2-benzothiazylsulfenamide in rats

The teratogenicity of N-cyclohexyl-2-benzothiazylsulfenamide (CBS) was studied in Wistar rats. Pregnant rats were given CBS at a dosage of 0.001, 0.01, 0.1 or 0.5% in the diet from Day 0 to Day 20 of pregnancy. Daily intakes of CBS were 0.7 mg kg-1 for the 0.001% group, 7.1 mg kg-1 for the 0.01% group, 69.6 mg kg-1 for the 0.1% group and 288.8 mg kg-1 for the 0.5% group. Maternal body weight gain during pregnancy in the 0.1 and 0.5% groups was significantly lowered. Food consumption during pregnancy in the CBS-treated groups, except for the 0.5% group, did not differ from that in the control group. Neither death nor clinical signs of toxicity were noted in the pregnant females of any group. Lowered weight in fetuses and the placentae were observed in the 0.5% group. There were no significant compound-related effects on the incidences of pre- and post-implantation losses and the number and ratio of live fetuses. Morphological examinations of the fetuses revealed no evidence of teratogenesis. It could be concluded that CBS possesses no adverse effects on the prenatal development of the offspring in rats at doses employed in the present study.

Distribution of extracellular matrix in the migratory pathway of avian primordial germ cells

The appearance and distribution of extracellular matrix (ECM) was documented along the migratory route of chicken primordial germ cells (PGCs). The antimouse embryonal carcinoma cell antibody, EMA-1, was used to label PGCs (Urven et al.: Development 103:299-304, 1988). Antibodies against laminin, fibronectin, chondroitin sulfate proteoglycan and collagen type IV were used to label extracellular matrix components. When the PGCs emerged from the epiblast, all four ECM molecules were restricted principally to the basement membrane of the epiblast. Chondroitin sulfate was also located between hypoblast cells during this period. In late germinal crescent stages, when the PGCs entered the lumina of blood vessels, the same ECM molecules were more widespread in the mesoderm and in extracellular spaces. In addition, laminin and collagen type IV were identified on lateral surfaces of ectodermal cells at this stage. When the germ cells moved through the mesenchyme into the germinal ridge, the ECM molecules were found around mesenchymal cells, and, in the cases of laminin, fibronectin and collagen type IV, in the basement membranes of the germinal ridge epithelia. Because the appearance of these ECM components is temporally and spatially correlated with the movement of PGCs, we suggest that early PGC migration may depend on their timely appearance.