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Knowledge on mode-of-action (MOA) is required to understand toxicological effects of compounds, notably in the context of risk assessment of mixtures. Such information is generally scarce, and often complicated by the existence of multiple MOAs per compound. Here, MOAs related to developmental craniofacial malformations were derived from literature, and assembled in a MOA network. A selection of gene expression markers was based on these MOAs. Next, these markers were verified by qPCR in zebrafish embryos, after exposure to reference compounds. These were: triazoles for inhibition of retinoic acid (RA) metabolism, AM580 and CD3254 for selective activation of respectively RA-receptor (RAR) and retinoid-X-receptor (RXR), dithiocarbamates for inhibition of lysyl oxidase, TCDD for activation of the aryl-hydrocarbon-receptor (AhR), VPA for inhibition of histone deacetylase (HDAC), and PFOS for activation of peroxisome proliferator-activated receptor-alpha (PPARα). Next, marker gene profiles for these reference compounds were used to map the profiles of test compounds to known MOAs. In this way, 2,4-dinitrophenol matched with the TCDD and RAR profiles, boric acid with RAR, endosulfan with PFOS, fenpropimorph with dithiocarbamates, PCB126 with AhR, and RA with triazoles and RAR profiles. Prochloraz showed no match. Activities of these compounds in ToxCast assays, and in silico analysis of binding affinity to the respective targets showed limited concordance with the marker gene expression profiles, but still confirmed the complex MOA profiles of reference and test compounds. Ultimately, this approach could be used to support modeling of mixture effects based on upfront knowledge of (dis)similarity of MOAs., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Chinese herbal medicines (CHMs) have been widely used during pregnancy, but feto-embryo safety tests are lacking. Here we evaluated in vitro embryotoxicity tests (IVTs) as alternative methods in assessing developmental toxicity of CHMs. Ten CHMs were selected and classified as strongly, weakly and non-embryotoxic. Three well validated IVTs and prediction models (PMs), including embryonic stem cell test (EST), micromass (MM) and whole embryo culture (WEC), were compared. All strongly embryotoxic CHMs were predicted by MM and WEC PM2. While all weakly embryotoxic CHMs were predicted by MM and WEC PM1. All non-embryotoxic CHMs were classified by EST, MM, but over-classified as weakly embryotoxic by WEC PM1. Overall predictivity, precision and accuracy of WEC determined by PM2 were better than EST and MM tests. Compared with validated chemicals, performance of IVTs for CHMs was comparable. So IVTs are adequate to identify and exclude embryotoxic potential of CHMs in this training set., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Many chemicals are going through a hazard-based classification and labeling process in Europe. Because of the significant public health implications, the best science must be applied in assessing developmental toxicity data. The European Teratology Society and Health and Environmental Sciences Institute co-organized a workshop to consider best practices, including data quality and consistency, interpretation of developmental effects in the presence of maternal toxicity, human relevance of animal data, and limits of chemical classes. Recommendations included larger historical control databases, more pharmacokinetic studies in pregnant animals for dose setting and study interpretation, generation of mechanistic data to resolve questions about whether maternal toxicity is causative of developmental toxicity, and more rigorous specifications for what constitutes a chemical class. It is our hope that these recommendations will form the basis for subsequent consensus workshops and other scientific activities designed to improve the scientific robustness of data interpretation for classification and labeling., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Background: Although there is strong evidence that some medications are teratogenic, the current lists of teratogens to be used in research are outdated. The objective of this study was to develop an updatable and systematic procedure to the classification of medications proven and potentially teratogenic in the first trimester of pregnancy, for use in research., Methods: We developed a two-step procedure for teratogen classification. Step 1 includes classifying the medications from Drugs in Pregnancy and Lactation: a Reference Guide to Fetal and Neonatal Risk (9th ed.) into two provisional lists: (1) teratogenic medications, and (2) potentially teratogenic medications. We also searched other references to add other medications. In Step 2, the Teratology Information System (TERIS) database was searched, and the medication was classified as teratogenic or potentially teratogenic according to a newly developed scheme. Expert consensus was used if a medication was not recorded in TERIS., Results: A total of 114 medications were identified in Drugs in Pregnancy and Lactation: a Reference Guide to Fetal and Neonatal Risk, with 57 medications in each provisional list. Seventy-eight medications were identified in other sources. A total of 135 medications were included in Step 2; the TERIS scheme classified 23 medications, and 112 medications required expert opinion. The two experts agreed on 78.6% of the medications (kappa = 0.63). We identified 91 teratogenic and 81 potentially teratogenic medications., Conclusion: Using reliable references, we established a systematic procedure to the classification of medications with evidence of or potential teratogenic risk. These exhaustive lists will be useful in teratology research and related fields., (© 2016 Wiley Periodicals, Inc.)

Background: When making decisions about medication use in pregnancy, women consult many information sources, including the Internet. The aim of this study was to assess the content of publicly accessible YouTube videos that discuss medication use in pregnancy., Methods: Using 2023 distinct combinations of search terms related to medications and pregnancy, we extracted metadata from YouTube videos using a YouTube video Application Programming Interface. Relevant videos were defined as those with a medication search term and a pregnancy-related search term in either the video title or description. We viewed relevant videos and abstracted content from each video into a database. We documented whether videos implied each medication to be "safe" or "unsafe" in pregnancy and compared that assessment with the medication's Teratogen Information System (TERIS) rating., Results: After viewing 651 videos, 314 videos with information about medication use in pregnancy were available for the final analyses. The majority of videos were from law firms (67%), television segments (10%), or physicians (8%). Selective serotonin reuptake inhibitors (SSRIs) were the most common medication class named (225 videos, 72%), and 88% of videos about SSRIs indicated that they were unsafe for use in pregnancy. However, the TERIS ratings for medication products in this class range from "unlikely" to "minimal" teratogenic risk., Conclusion: For the majority of medications, current YouTube video content does not adequately reflect what is known about the safety of their use in pregnancy and should be interpreted cautiously. However, YouTube could serve as a platform for communicating evidence-based medication safety information., (Copyright © 2015 John Wiley & Sons, Ltd.)

Mammalian fetal development is easily disrupted by exogenous agents, making it essential to test new drug candidates for embryotoxicity and teratogenicity. To standardize the testing of drugs that might be used to treat pregnant women, the U.S. Food and Drug Administration (FDA) formulated special grade categories, labeled A, B, C, D and X, that define the level of risk associated with the use of a specific drug during pregnancy. Drugs in categories (Cat.) D and X are those with embryotoxic and/or teratogenic effects on humans and animals. However, which stages of pregnancy are affected by these agents and their molecular mechanisms are unknown. We describe here an embryonic stem cell test (EST) that classifies FDA pregnancy Cat.D and Cat.X drugs into 4 classes based on their differing effects on primitive streak formation. We show that ~84% of Cat.D and Cat.X drugs target this period of embryogenesis. Our results demonstrate that our modified EST can identify how a drug affects early embryogenesis, when it acts, and its molecular mechanism. Our test may thus be a useful addition to the drug safety testing armamentarium.

Classification of substances as teratogenic is based on the observation of external, visceral and skeletal anomalies. Characterization of anomalies as variation or malformation is contingent upon their postnatal persistence and adversity to health. Lack of information thereof may result in inconsistent or incorrect classification. The aim of this work is the examination of vertebral skeletal anomalies regarding their postnatal fate on PNDs 7 and 21. The anomalies unossified, asymmetric ossification, bipartite ossification, hemicentric, as well as misshapen, did not persist up to PND21 and should be classified as a variation. The finding, cervical vertebra centrum dumbbell-shaped, should be categorized as a malformation due to its continued presence on PND 21. Lumbar centrum supernumerary sinister/dexter/sinister+dexter should also be classified as a malformation. This study demonstrates that postnatal examination is useful and substantially improves the ability to perform a scientifically sound classification of an anomaly compared to investigations terminated on GD 21., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Histone deacetylases (HDACs) play a major role in chromatin remodeling, gene regulation, and cellular signaling. While the role of each class of HDAC during normal development is unclear, several HDAC inhibitors are embryotoxic; the mechanisms leading to the teratogenicity of HDAC inhibitors are not known. Here, we investigated the effects of class-specific HDAC inhibitors on the development of organogenesis-stage murine limbs. Timed-pregnant COL2A1-ECFP, COL10A1-mCherry, and COL1A1-YFP CD1 reporter mice were euthanized on gestation day 12; embryonic forelimbs were excised and cultured in vitro for 1, 3, and 6 days in the presence or absence of MS275 (a class I HDAC inhibitor), MC1568 (a class III HDAC inhibitor), Sirtinol (a class II HDAC inhibitor), or valproic acid, our positive control. Fluorescently tagged COL2A1, COL10A1, and COL1A1 served as markers of the differentiation of proliferative chondrocytes, hypertrophic chondrocytes, and osteoblasts, respectively. MS275 and valproic acid caused a reduction in expression of all three markers, suggesting effects on both chondrogenesis and osteogenesis. MC1568 had no effect on chondrocyte markers and mildly inhibited COL1A1 expression at 6 days. Sirtinol had no effect on COL2A1 expression or chondrocyte differentiation 1 day following exposure; however, it caused a drastic regression in limb cartilage and reduced the expression of all three differentiation markers to nearly undetectable levels at 6 days. MS275 and Sirtinol caused a 2.2- and 2.7-fold increase, respectively, in cleaved-caspase 3, a marker of apoptosis, suggesting embryotoxicity. These data demonstrate that inhibition of class I or III HDACs causes severe developmental toxicity and is highly teratogenic., (© The Author 2015. Published by Oxford University Press on behalf of the Society of Toxicology. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.)

In the last couple of years, the interest in the zebrafish embryotoxicity test (ZET) for use in developmental toxicity assessment has been growing exponentially. This is also evident from the recent proposal for updating the ICHS5 guideline. The methodology of the ZET used by the different groups varies greatly. To further evaluate its successfulness and to take the ZET to the next level, harmonization of procedures is crucial. In the present study, based on literature and empirical data, the most optimal study design regarding temperature, test chamber, exposure period, presence of chorion, solvent use, exposure method, choice of concentrations, and teratogenic classification is proposed. Furthermore, our morphology scoring system is reported in detail as protocol to further enhance study design harmonization., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Previously we showed a battery consisting of CALUX transcriptional activation assays, the ReProGlo assay, and the embryonic stem cell test, and zebrafish embryotoxicity assay as 'apical' tests to correctly predict developmental toxicity for 11 out of 12 compounds, and to explain the one false negative [7]. Here we report on applying this battery within the context of grouping and read across, put forward as a potential tool to fill data gaps and avoid animal testing, to distinguish in vivo non- or weak developmental toxicants from potent developmental toxicants within groups of structural analogs. The battery correctly distinguished 2-methylhexanoic acid, monomethyl phthalate, and monobutyltin trichloride as non- or weak developmental toxicants from structurally related developmental toxicants valproic acid, mono-ethylhexyl phthalate, and tributyltin chloride, respectively, and, therefore, holds promise as a biological verification model in grouping and read across approaches. The relevance of toxicokinetic information is indicated., (Copyright © 2014 Elsevier Inc. All rights reserved.)

There is an issue in the EU classification of substances for carcinogenicity and for reproductive or developmental toxicity which has brought difficulties to those involved in the process. The issue lies in the inability of the classification system to distinguish between carcinogens and reproductive toxicants with different levels of concern. This has its origins in the early years of toxicology when it was thought that a relatively small number of chemicals would be either carcinogens or reproductive toxicants, but this has turned out not to be the case. This can cause problems in communicating to the users of chemicals, including the public, the nature of the hazard presented by chemicals. Processes have been developed within the classification system for setting specific concentration limits which assess the degree of hazard for carcinogens and reproductive toxicants as high, medium or low. However these categories are not otherwise used in classification. It is proposed that their wider use would bring the advantages of transparency, clarity of communication, certainty of the process and would allow chemicals with a high degree of hazard to be identified and managed in an appropriate way., (Copyright © 2014. The Authors. Journal of Applied Toxicology Published by John Wiley & Sons Ltd.)

High molecular weight chitosan (HMWCS) is effective at hemostasis and wound healing, and will be potentially used on injured internal organs. To study its prenatal and developmental effect in vivo, forty-four ICR pregnant mice per group were singly injected intraperitoneally at 0, 125, 500 or 2000 mg/kg body weight, respectively, on gestation day 6 (GD6). Clinical signs, reproductive capacity, fetus and infant developments, and histopathological changes were then observed. The results showed that the treatment of HMWCS could decrease body weights and food consumptions, and induce diarrhea, vaginal bleeding, and some other adverse effects in F0 mice. For the emaciation and threatened abortion of pregnant mice, the numbers of live fetuses and early resorption were reduced significantly in HMWCS groups. However, the developments of F1 and F2 mice were not affected, except for lower weights of the body and some organs. In addition, the NOAEL of HMWCS in maternal toxicity was considered to be less than 125 mg/kg, and the NOAEL in developmental toxicity was 125 mg/kg., (Copyright © 2013 Elsevier Inc. All rights reserved.)

In 2007, a new European chemicals legislation was implemented: Regulation (EC) No. 1907/2006, also known as "REACH." It obliges companies to take the main responsibility for the valid information on the safe use of the chemicals they manufacture and/or place on the European market. So they must, for example, register their chemicals at the European Chemicals Agency (ECHA) and submit extensive substance-related registration dossiers containing information on the substances' intrinsic hazardous properties and documentation of their risk assessment. REACH regulates the registration and evaluation process as well as the authorization and restriction procedure. In addition, classification, labeling, and packaging of chemicals apply in accordance with Regulation (EC) No. 1272/2008 ("CLP Regulation"). It implements almost completely the provisions of the United Nations Globally Harmonised System of Classification and Labelling of Chemicals (UN GHS) into European legislation and will fully replace the Dangerous Substances Directive (67/548/EEC) and the Dangerous Preparations Directive (1999/45/EC) by 2015. According to both the old and the new classification system, teratogenic chemicals are classified as developmental toxicants, with developmental toxicity falling within the hazard class of reproductive toxicity. REACH as well as the CLP Regulation provide several procedures in which reproductive toxicants take a special position because their harmful effects are considered particularly serious. Teratogenic substances are not explicitly named by these legal texts but, as they constitute as developmental toxicants a hazard differentiation of reproductive toxicity, they are implicitly always included by the provisions.

Background: Psoralea corylifolia L. (PC) was commonly used to treat miscarriages clinically. The aim of this study was to examine its embryotoxicity in mice and embryonic stem cells (ESCs)., Methods: Quality control of PC extract including reference marker compounds, pesticide residues, and heavy metals was authenticated with HPLC, Gas chromatography-mass spectrometry (GC-MS), and inductively coupled plasma-mass spectrometry. Pregnant mice were randomly assigned into five groups and dosed with distilled water (G1), PC extract of 2 (G2), 4 (G3), or 8 g/kg/day (G4), and vitamin A (G5). Meanwhile, half maximal inhibitory concentration values for ESCs and 3T3 cells were identified in a cytotoxicity assay, and apoptosis in neuroepithelium was assessed by transmission electron microscopy., Results: In the G4 group, a statistically significant decrease in the total fetus, live fetus, and gravid uterine weight, and increase in the resorbed fetus, postimplantation loss, and neuroepithelial apoptosis as well as maternal liver-weight were found (p < 0.05)., Conclusions: PC extracts at 8 g/kg/day might cause fetal toxicity and maternal liver damage in mice, although it did not cause typical malformation and ESC's cytotoxicity in this experiment. Our data suggested that high dosage and long-term administration of PC preparations may not be safe for pregnant women., (© 2012 Wiley Periodicals, Inc.)

Objective: We aimed to study the pregnancy outcomes of women exposed to isotretinoin and to identify the factors influencing their decision to request an abortion., Methods: The study prospectively identified 79 women who had been treated for acne with isotretinoin during the periconceptional period, and who were followed up until completion of their pregnancy. Characteristics of exposure and doses were self-reported by participants., Results: Of the 56 participants who decided to continue their pregnancy, there were 11 spontaneous abortions and 44 women who delivered healthy full-term babies of which 19 had been exposed to isotretinoin <1 month before conception or during pregnancy. In a nominal logistic regression analysis including 68 patients who provided adequate information for analysis, exposure to isotretinoin >2 weeks post-conception and pregnancy termination recommended by the first-contact physician were found to be significantly associated with patients' decision to undergo elective abortion: adjusted OR = 9.87 (95% CI 1.18-82.34) and 12.51 (95% CI 2.36-66.29), respectively., Conclusions: Our study reports an elevated rate of babies born without evidence of gross malformation or neurofunctional abnormality even tough exposure occurred during the teratogenic risk period. However, caution is recommended since a substantial risk of congenital malformations has been reported with low doses of isotretinoin and at exposures limited to early pregnancy. We also found that primary-care physicians may influence patients' decision to request pregnancy termination independently of their timing of exposure to isotretinoin.

The emergency physician frequently encounters women who seek care because of pregnancy- and nonpregnancy-related complaints. Many medications are safe for use during pregnancy, including several that are listed as potential teratogens based on the Food and Drug Administration's (FDA) pregnancy classification; but it is important that the emergency physician know and recognize which drugs can be given in pregnancy and which drugs are absolutely contraindicated. Expert resources should be identified and used because the FDA's classification of drugs based on pregnancy risk does not represent the most up-to-date or accurate assessment of a drug's safety., (Copyright © 2012 Elsevier Inc. All rights reserved.)

The Threshold Toxicological Concern (TTC) is based on the concept that reasonable assurance of safety can be given if exposure is sufficiently low. We report on the evaluation of BASF's data for oral developmental toxicity studies in rabbits with 48 NOAEL values for maternal and developmental toxicity. The 5th percentile of the NOAEL distributions was calculated to be 5mg/kgbw/d for both maternal and developmental toxicity. From literature 56 compounds tested in rabbits were taken and combined with values from BASF's studies. The 5th percentile value for developmental toxicity of these 104 studies (mostly active ingredients) was 2mg/kgbw/d. Thus, a TTC value of 4μg/kgbw/d was calculated using a safety factor of 500 to account for relatively small database. This value is in the same range as the TTC value for developmental toxicity in rats of 8μg/kgbw/d. The lower value may serve as guidance to determine whether further evaluation is needed or whether to rely on a TTC value for industrial chemicals or low concentration (environmental) contaminants if exposure is sufficiently low. A comparison of 30 compounds tested at BASF in both species, suggests that rabbits are not more sensitive than rats. We encourage others to publish data on rabbit developmental toxicity., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Background: Cancer is the second leading cause of death among women of reproductive age. Although the coincidence of pregnancy and cancer is rare and treatment may sometimes be safely delayed, the use of chemotherapeutic agents in pregnancy is sometimes unavoidable or inadvertent., Methods: We review the literature for the use of antineoplastic agents in single-agent and combination therapy from 1951 through June 2012. We also summarize the evidence relating to teratogenicity of disorder-specific combination chemotherapy treatments for those malignancies frequently encountered in women of childbearing age. Major endpoints were called "adverse pregnancy outcomes" (APOs), to include structural anomalies (congenital malformations), functional defects, blood or electrolyte abnormalities, stillbirths, spontaneous abortions (miscarriages), and fetal, neonatal, or maternal deaths., Results: The registry totals 863 cases. Rates of APOs (and congenital malformations) after any exposure were 33% (16%), 27% (8%), and 25% (6%), for first, second, and third trimesters. Among the groups of cancer drugs, antimetabolites and alkylating agents have the highest rates of APOs. Mitotic inhibitors and antibiotics seem more benign. Mixed results were observed from single-agent exposure, often because of small numbers of exposures. As a whole, the alkylating agents and antimetabolites are more harmful when given as a single agent rather than as part of a regimen. First-trimester exposure poses a more permanent risk to the fetus., Conclusions: Systematic ascertainment of women early in pregnancy, preferably in a population base, is needed for assessment of true risks. Long-term follow-up is needed to rule out neurobehavioral effects., (Copyright © 2012 Wiley Periodicals, Inc.)

This study describes a novel rat whole embryo culture (rWEC) teratogenicity assay that applies a simplified experimental design and statistical prediction model, resulting in reduced animal requirements and increased throughput with low prediction error rate for classifying teratogenic potential of compounds. A total of 70 compounds (38 teratogens and 32 nonteratogens) were evaluated, and the prediction model was generated from a dataset of 59 compounds. The rWEC assay requires only one test concentration (1μM) and three structural endpoints (group average morphological scores of spinal cord, heart, and number of somite pairs), which are used in a recursive partition model for classifying teratogenic liability. The model fitting concordance between the WEC assay and in vivo outcome was 83% with a standard deviation (SD) of 4.9%. The predictivity for future compounds was evaluated by using two statistical methods. Fivefold cross-validation estimated the predictivity of this model at 73% (SD 5.8%). A second estimation of predictivity was obtained from an independent test set of 11 compounds that were not used to build the prediction model and reached 82% (SD 11.6%). The overall estimate for prediction concordance is 74% (SD 5.2%). There is no statistically significant difference (p value > 0.50) in the predictivity between this model and the model supporting European Center for the Validation of Alternative Methods WEC assay with predictivity of 80% (SD 10.6%). Overall, the streamlined WEC assay is estimated to reduce animal use and operational costs by more than 50%. It substantially improves results turnaround with no loss of predictivity.

Testing for embryotoxicity in vitro is an attractive alternative to animal experimentation. The embryonic stem cell test (EST) is such a method, and it has been formally validated by the European Centre for the Validation of Alternative Methods. A number of recent studies have underscored the potential of this method. However, the EST performed well below the 78% accuracy expected from the validation study using a new set of chemicals and pharmaceutical compounds, and also of toxicity criteria, tested to enlarge the database of the validated EST as part of the Work Package III of the ReProTect Project funded within the 6th Framework Programme of the European Union. To assess the performance and applicability domain of the EST we present a detailed review of the substances and their effects in the EST being nitrofen, ochratoxin A, D-penicillamine, methylazoxymethanol, lovastatin, papaverine, warfarin, β-aminopropionitrile, dinoseb, furosemide, doxylamine, pravastatin, and metoclopramide. By delineation of the molecular mechanisms of the substances we identify six categories of reasons for misclassifications. Some of these limitations might also affect other in vitro methods assessing embryotoxicity. Substances that fall into these categories need to be included in future validation sets and in validation guidelines for embryotoxicity testing. Most importantly, we suggest conceivable improvements and additions to the EST which will resolve most of the limitations.

The zebrafish embryotoxicity test (ZET) is considered a promising alternative model in predictive toxicology. Currently, morphological assessment of the embryo is the main readout for this assay. However, implementation of transcriptomics may help to detect more subtle effects, which may increase the sensitivity and predictability of the test. In this study, we tested a concentration response of flusilazole in the ZET. After exposure for 24 h postfertilization, microarray analysis revealed a number of processes to be regulated in a concentration-dependent way. We identified development related processes, retinol metabolism and transcription, as well as processes corresponding to the antifungal mechanism of action, steroid biosynthesis, and fatty acid metabolism, to be differentially regulated. Retinol metabolism and transcription were already significantly altered at concentrations that were not inducing morphological effects. Differential expression of genes related to steroid biosynthesis and fatty acid metabolism showed a concentration response similar to morphological response. An increase in concentration was also positively associated with an increase in magnitude of expression for individual genes within functional processes. Our study shows that transcriptomics analysis in the ZET is a more sensitive readout of compound-induced effects than morphological assessment. However, the interpretation of differential gene expression in terms of predicting morphological effects is not straightforward and requires further study.

The majority of new preventative and therapeutic vaccines are now assessed for developmental toxicity according to guidelines issued by the FDA in 2006. Despite the absence of confirmed effects in humans, vaccines are frequently suspected of having adverse side-effects on the development of children. Such suspicions are perhaps unavoidable considering the extremely widespread use of vaccines. The preclinical developmental toxicology studies are designed to assess possible influences of each component of the vaccine formulation-and the induced antibodies-on the development of the conceptus, neonate and suckling organism. Immune modulation by a vaccine or an adjuvant could, for instance, affect the outcome of pregnancy by interfering with the natural shift in immune balance of the mother during gestation. Maternal immunoglobulins are transferred from the mother to the offspring in order to confer passive immunity during early life. This maternal antibody transport is prenatal in humans and monkeys, but tends to be delayed until after birth in other species. Therefore, a suitable model species needs to be chosen for preclinical studies in order to ensure exposure of the foetus to the induced maternal antibodies following vaccination. Rabbits are the best laboratory model for prenatal immunoglobulin transfer, but rodents are more practical for the necessary postnatal investigations. Non-human primates are the only appropriate models for the testing of vaccines that are not immunogenic in lower species. It is advisable to test new adjuvants separately according to the ICH S5(R2) guidelines. Preclinical paediatric investigations are not currently required for vaccines, even though most vaccines are given to children. Other areas of regulatory concern include developmental immunotoxicity and effects on the preimplantation embryo. Because of the limitations of the available animal models for developmental toxicity testing, pharmacovigilance is essential., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Over the past decade, the use of gene expression profiling (i.e., toxicogenomics or transcriptomics) has been established as the vanguard "omics" technology to investigate exposure-induced molecular changes that underlie the development of disease. As this technology quickly advances, researchers are striving to keep pace in grasping the complexity of toxicogenomic response while at the same time determine its applicability for the field of developmental toxicology. Initial studies suggest toxicogenomics to be a promising tool for multiple types of study designs, including exposure-response investigations (dose and duration), chemical classification, and model comparisons. In this review, we examine the use of toxicogenomics in developmental toxicology, discussing biological and technical factors that influence response and interpretation. Additionally, we provide a framework to guide toxicogenomic investigations in the field of developmental toxicology.

Hoodia gordonii extract was orally administered by gavage to groups of 22 female New Zealand white rabbits from day 3-28 after mating at doses of 0 (control), 3, 6 or 12 mg/kg bodyweight/day. These doses were reached by a dose escalation phase between days 3 and 7 after mating. As well as a vehicle control group, a control group pair-fed to the high dose was also included. On day 29 after mating the females were euthanized and examined. Treatment at 6 or 12 mg/kg/day was associated with a dose-related reduction in feed intake and bodyweight gain. Feed consumption and bodyweight gain was unaffected at 3mg/kg/day. In spite of marked maternal effects at 12 mg/kg/day, reproductive indices were unaffected at all doses and there were no effects on fetal or placental weights and no morphological changes in the fetuses. The no-observed-effect level (NOEL) for developmental effects was therefore 12 mg/kg/day, and the maternal NOEL was 3mg/kg/day. At doses that caused marked maternal effects, H. gordonii extract did not affect embryonic or fetal development in a species that is considered predictive of developmental toxicity in man., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

A promising in vitro zebrafish developmental toxicology assay was generated to test compounds for their teratogenic potential. The assay's predictivity is approximately 87% in AB strain fish (Brannen KC et al., Birth Defects Res B Dev Reprod Toxicol 89:66-77, 2010). The procedure entails exposing dechorionated gastrulation-stage embryos to a range of compound concentrations for 5 days throughout embryonic and larva development. The larvae are evaluated for viability in order to identify an LC25 (the compound concentration in which 25% lethality is observed) and morphological anomalies using a numerical score system to identify the NOAEL (no observed adverse effect level). These values are used to calculate the teratogenic index (LC25/NOAEL ratio) of each compound. If the teratogenic index is equal to or greater than 10 then the compound is classified as a teratogen, and if the ratio is less than 10 then the compound is classified as a nonteratogen (Brannen KC et al., Birth Defects Res B Dev Reprod Toxicol 89:66-77, 2010).

Toxicity testing in the 21st century is moving toward using high-throughput screening assays to rapidly test thousands of chemicals against hundreds of molecular targets and biological pathways, and to provide mechanistic information on chemical effects in human cells and small model organisms. First-generation predictive models for prenatal developmental toxicity have revealed a complex web of biological processes with many connections to vasculogenesis and angiogenesis. This review examines disruption of embryonic vascular development as a potential adverse outcome pathway leading to developmental toxicity. We briefly review embryonic vascular development and important signals for vascular development (local growth factors and cytokines such as vascular endothelial growth factor-A and TGF-beta, components in the plasminogen activator system, and chemotactic chemokines). Genetic studies have shown that perturbing these signals can lead to varying degrees of adverse consequences, ranging from congenital angiodysplasia to fetal malformations and embryolethality. The molecular targets and cellular behaviors required for vascular development, stabilization and remodeling are amenable to in vitro evaluation. Evidence for chemical disruption of these processes is available for thalidomide, estrogens, endothelins, dioxin, retinoids, cigarette smoke, and metals among other compounds. Although not all compounds with developmental toxicity show an in vitro vascular bioactivity signature, many 'putative vascular disruptor compounds' invoke adverse developmental consequences. As such, an adverse outcome pathway perspective of embryonic vascular development can help identify useful information for assessing adverse outcomes relevant to risk assessment and efficient use of resources for validation., (Copyright © 2011 Wiley Periodicals, Inc.)

Environmental Protection Agency's ToxCast project is profiling the in vitro bioactivity of chemicals to assess pathway-level and cell-based signatures that correlate with observed in vivo toxicity. We hypothesized that developmental toxicity in guideline animal studies captured in the ToxRefDB database would correlate with cell-based and cell-free in vitro high-throughput screening (HTS) data to reveal meaningful mechanistic relationships and provide models identifying chemicals with the potential to cause developmental toxicity. To test this hypothesis, we built statistical associations based on HTS and in vivo developmental toxicity data from ToxRefDB. Univariate associations were used to filter HTS assays based on statistical correlation with distinct in vivo endpoint. This revealed 423 total associations with distinctly different patterns for rat (301 associations) and rabbit (122 associations) across multiple HTS assay platforms. From these associations, linear discriminant analysis with cross-validation was used to build the models. Species-specific models of predicted developmental toxicity revealed strong balanced accuracy (> 70%) and unique correlations between assay targets such as transforming growth factor beta, retinoic acid receptor, and G-protein-coupled receptor signaling in the rat and inflammatory signals, such as interleukins (IL) (IL1a and IL8) and chemokines (CCL2), in the rabbit. Species-specific toxicity endpoints were associated with one another through common Gene Ontology biological processes, such as cleft palate to urogenital defects through placenta and embryonic development. This work indicates the utility of HTS assays for developing pathway-level models predictive of developmental toxicity.

This study tested whether maternal exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) may disrupt the development of neuroendocrine system of their offspring during the perinatal period. TCDD (0.2 or 0.4 μg/kg body weight) was orally administered to pregnant rats from gestation day (GD) 1 to lactation day (LD) 30. Potential effects on neuroendocrine function were evaluated by measuring serum thyroid hormone levels in pregnant rats and their offspring and measuring some biochemical parameters in cerebellum of these offspring on GD 16 and 19, and LD 10, 20, and 30. In both treated groups, a decrease in serum thyroxine (T4), triiodothyronine (T3) and increase in thyrotropin (TSH) levels were noticed during the tested days in dams and offspring, as well as GH levels were decreased in offspring with respect to control group. In cerebellum of control offspring, the levels of monoamines, γ-aminobutyric acid (GABA) and acetylcholinesterase (AchE) were found to be increased from GD 16 to LD 30. The hypothyroid conditions due to both maternal administrations of TCDD produced inhibitory effects on monoamines and AchE, and stimulatory actions on GABA in cerebellum of offspring. These alterations were dose and age dependent. Overall, these results suggest that TCDD may act as neuroendocrine disruptor., (Crown Copyright © 2011. Published by Elsevier Ltd. All rights reserved.)

The extract of pineapple leaves (EPL) has anti-diabetic and anti-dyslipidemic effects and can be developed into a promising natural medicine. This study was conducted to evaluate EPL's effects on developmental parameters in order to provide evidence of its safety before potential medical use. Five groups were included: a negative control that was given distilled water daily, a positive control that was dosed 7 mg/kg cyclophosphamide (CP) every two days, and three groups that were respectively dosed 2.0, 1.0, and 0.5 g/kg EPL daily. Female rats were dosed during the organogenesis period of gestation days (GD) 7-17 and terminated on GD 20. A series of parameters were examined. Data revealed that CP significantly reduced maternal body weight gains, caused maternal organ weight alterations, reduced female fertility, disturbed fetal growth and development, and caused marked teratogenic effects on fetal appearances, skeleton and internal organs. Distilled water and the three high doses of EPL did not cause any of the aforementioned effects. This study concluded that orally administered EPL is safe to rats during embryonic development., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Cordyceps guangdongensis as a kind of fungus, has been discovered and cultivated successfully in recent years. However, its safety assessments have not been studied. In this report, a serial of tests for toxicological safety assessments were depicted in details. These tests included bacterial reverse mutation (Ames) study, bone marrow cell micronucleus test in mice, sperm aberration test in mice, teratogenicaction test in rats, acute toxicity test and 13-week oral toxicity study in rats. After a profound analysis of these tests, it clearly demonstrated that C. guangdongensis did not have any mutagenic, clastogenic nor genotoxic effects; the oral LD50 of the biomass in rats was greater than 15 g/kg body weight; the no-observed adverse-effect-levels (NOAEL) was 5.33 g/kg body weight according to the 13-week oral toxicity analysis. Therefore, a conclusion can be drawn that C. guangdongensis is considered safe for long term consumption., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

The embryonic stem cell test (EST) is a validated in vitro method to assess the embryotoxic potential of compounds and is a promising tool for drug screening. EST requires microscopic observation of beating cardiomyocytes differentiated from embryonic stem cells as a toxicological endpoint. However, this process is time-consuming and lacks throughput performance. To improve the analysis, we introduced an electrophysiological method with a microelectrode array system for the evaluation of differentiated cardiomyocytes. Embryotoxic (valproic acid, verapamil, and 5-fluorouracil) and non-embryotoxic (penicillin G, d-camphor, and isoniazid) compounds were assessed with the system. Mouse embryonic stem cells were differentiated into cardiomyocytes and treated with each compound during the differentiation process. The embryotoxicity of each compound was then assessed by measuring the field potentials of differentiated cardiomyocytes using the microelectrode array system, as well as by microscopic evaluation. All the embryotoxic compounds dose-dependently inhibited the field potential formation and the myocardial beating of differentiated cells, while the non-embryotoxic compounds did not affect either endpoint. The detection capabilities of the two assay methods were similar. These results indicated that the field potential measurements can be used as an alternative endpoint of EST. Moreover, the field potential can be measured automatically, introducing a high throughput performance compared to the conventional microscopic observation. We therefore concluded that the endpoint analysis with the microelectrode array system improves the original EST and can be useful for the assessment of the embryotoxic potential of compounds.

Detrimental effects of chlorides on the developing bone as well as the adult skeleton have been widely debated in the past decades. The FDA and other National Institutes have not recommended a reduction in the dietary intake of chlorides despite alarming in vitro and in vivo studies. This study employs the embryonic stem cell test to unambiguously characterize the effect of four chlorides with increasing valence, NaCl, LiCl, MgCl(2) and AlCl(3), utilizing the capacity of murine embryonic stem cells to differentiate into bone forming cells in vitro. Contrasting cytotoxicity of these chlorides to the inhibition of osteogenic differentiation assayed with a quantitative calcium assay and morphometric image analysis, we suggest here a potential negative effect on fetal bone development for all four chlorides. Although this effect was clearer for AlCl(3) than for the other tested chlorides, we suggest extreme caution should still be given when administering any chloride during pregnancy., (Published by Elsevier Inc.)

Nanoparticles (NPs) are emerging as promising biomedical tools thanks to their peculiar characteristics. Our purpose was to investigate the embryotoxicity of cobalt ferrite and gold NPs through the Embryonic Stem Cell Test (EST). The EST is an in vitro standard assay, which permits to classify substances as strongly, weakly or non-embryotoxic. Due to the particular physical-chemical nature of nanoparticles, we introduced a modification to the standard protocol exposing the Embryonic Stem Cells (ES-D3) to nanoparticles only during the first 5 days of the assay. Moreover, we proposed a method to discriminate and compare the embryotoxicity of the substances within the weakly embryotoxic range. Our ID(50) results permit to classify cobalt ferrite nanoparticles coated with gold and silanes as non-embryotoxic. The remaining nanoparticles have been classified as weakly embryotoxic in this decreasing order: gold salt (HAuCl(4).3H(2)O)>cobalt ferrite salt (CoFe(2)O(4))>cobalt ferrite nanoparticles coated with silanes (Si-CoFe)>gold nanoparticles coated with hyaluronic acid (HA-Au)., (Copyright 2010 Elsevier Inc. All rights reserved.)

Quaternium-15 is an antimicrobial agent used in cosmetics as a cosmetic preservative and antistatic agent. Little systemic toxicity was reported in most single-dose or repeated-dose animal studies. Quaternium-15 was an oral teratogen, but not a dermal teratogen, in rats at doses that exceeded the expected cumulative exposure from cosmetics. The frequency of sensitization increased in North America but not in Europe, where Quaternium-15 is used less often. In almost all animal and human studies, Quaternium-15 at 0.2% was not a sensitizer. The weight of evidence suggested that a 0.2% concentration is not a sensitizer and that cosmetic products containing Quaternium-15 up to that level are safe.

Background: Aperi- and postnatal reproduction toxicity study was conducted in rats treated with Hematide, a synthetic PEGylated peptidic erythropoiesis stimulating agent (ESA)., Methods: Hematide, at IV doses of 0, 0.5, 3, and 15 mg/kg, was administered from implantation through lactation on gestation days (GDs) 5 and 18 and lactation day (LD) 13., Results: Hematide induced pronounced polycythemia in all Hematide-treated dams. On LDs 2 and 21, hemoglobin (Hgb) increases above control levels were 3.1, 5.2, and 5.0 g/dL and 4.1, 5.1, and 5.5 g/dL at the 0.5, 3, and 15 mg/kg/dose, respectively. There were no effects on parturition, lactation, or maternal behavior in the F0 generation female rats. A slight decrease in pup viability on postpartum days 2-4 and lower body weights and/or body weight gain for the F1 generation were associated with pronounced polycythemia and decreases in maternal body weight gain and/or food consumption at > or =3 mg/kg/dose. Hematide fetal exposure was negligible. No Hematide effect, other than on growth and survival, was noted on developmental, functional, mating, and fertility end points in the F1 generation rats, and no effect on litter or fetal parameters was observed in the F2 generation. The maternal no-observed-adverse-effect level (NOAEL) for Hematide was 0.5 mg/kg, and the NOAEL for parturition and maternal behavior was 15 mg/kg. The NOAEL for F1 pup viability and growth was 0.5 mg/kg/dose., Conclusions: In conclusion, the Hematide-associated adverse findings were attributed to exaggerated erythropoiesis (pronounced and prolonged polycythemia) resulting from administration of an ESA to pregnant animals., (2010 Wiley-Liss, Inc.)

The present paper summarizes data on the reproductive and developmental toxicity of hydrofluorocarbons (HFCs), including pentafluoroethane (HFC-125), 1,1,1,2-tetrafluoroethane (HFC-134a), 1,1,1-trifluoroethane (HFC-143a), 1,1-difluoroethane (HFC-152a), difluoromethane (HFC-32) and 1,1,1,3,3-pentafluoropropane (HFC-245fa), used as refrigerants, published in openly available scientific literature. No developmental toxicity of HFC-125 was found even at 50,000 ppm in rats or rabbits. Although HFC-134a exhibited no dominant lethal effect or reproductive toxicity in rats, it caused low body weight in pre- and postnatal offspring and slightly retarded skeletal ossification in fetuses at 50,000 ppm in rats. No maternal or developmental toxicity was noted after exposure to HFC-143a even at 40,000 ppm in rats or rabbits or HFC-152a even at 50,000 ppm in rats. HFC-32 is slightly maternally and developmentally toxic at 50,000 ppm in rats, but not in rabbits. HFC-245fa caused decreases in maternal body weight and food consumption at 10,000 and 50,000 ppm and fetal weight at 50 000ppm. No evidence of teratogenicity for these HFCs was noted in rats or rabbits. There is limited information about the reproductive toxicity of these HFCs. Animal studies remain necessary for risk assessments of chemicals because it is difficult to find alternative methods to determine the toxic effects of chemicals. It is required to reduce emissions of organic vapors containing HFCs to reduce the risk of exposure., (Copyright 2009 Elsevier Inc. All rights reserved.)

Background: Ginkgo biloba extract (GBE) is an herbal medicine used for treating neurodegenerative diseases, cerebrovascular insufficiency, peripheral arterial occlusive disease, and also vestibular disturbance. Some components of GBE have presented estrogenic effects and, in a previous study, high dosages of GBE caused intra-uterine growth retardation in fetuses of Wistar rats treated during the fetogenesis period., Methods: Pregnant Wistar rats were treated, through gavage, with different dosages of aqueous GBE (3.5, 7.0, and 14.0 mg/Kg/day), during the tubal transit and implantation period. Rats were killed on the 15th day of pregnancy and the following parameters were evaluated: clinical symptoms of maternal toxicity; maternal body weight; feed and water intake; maternal liver, kidney, and ovary weights; number of corpora lutea; implants per group ratio; pre- and post-implantation loss per group ratio; live fetuses mean; dead fetuses percentage; fetus and placenta weight per offspring ratio; and fetal external malformation., Results: No significant alteration was found for both the maternal and embryonic parameters evaluated., Conclusions: The GBE treatment in pregnant Wistar rats, during the tubal transit and implantation period, caused no toxic effect on the maternal organism and did not induce embryonic death, growth retardation, and/or fetal malformations., (2010 Wiley-Liss, Inc.)

Background: The potential embryotoxic and teratogenic effects of decabromodiphenyl ethane (DBDPEthane; CASRN 84852-53-9) were evaluated in prenatal developmental studies using rats and rabbits and performed in accordance with international guidelines and Good Laboratory Practice standards. Preliminary dose-range-finding studies were conducted, which indicated doses up to 1,250 mg/kg-day were well tolerated by both rats and rabbits., Methods: For the developmental studies, animals were administered DBDPEthane via gavage at dosage levels of 0, 125, 400, or 1,250 mg/kg-day from gestation day (GD) 6 through 15 for rats and GDs 6 through 18 for rabbits. All female rats and rabbits were sacrificed on GD 20 or GD 29, respectively, and subjected to cesarean section. Fetuses were individually weighed, sexed, and examined for external, visceral and skeletal abnormalities., Results: No treatment-related mortality, abortions, or clinical signs of toxicity were observed during the study. Body weights, body weight gain, and food consumption were not affected by treatment. No significant internal abnormalities were observed in either species on necropsy. Cesarean section parameters were comparable between control and treated groups. No treatment-induced malformations or developmental variations occurred., Conclusions: Based on these results, no evidence of maternal toxicity, developmental toxicity, or teratogenicity was observed in rats or rabbits treated with DBDPEthane at dosage levels up to 1,250 mg/kg-day., (2010 Wiley-Liss, Inc.)

Background: CNTO 530is a biopharmaceutical consisting of a novel peptide that mimics the actions of erythropoietin, fused to the Fc fragment of human IgG4. Pharmacokinetic and pharmacodynamic studies showed that CNTO 530 produced sustained increases in red blood cell parameters in rats and rabbits and that the serum half life of CNTO 530 was 2 days in rabbits and 3 days in rats., Methods: For the evaluation of embryofetal development, CNTO 530 was injected at loading doses of 0, 0.9/1, 6, or 60 mg/kg subcutaneously (SC) on gestation day (GD)7 followed by maintenance doses of 0, 0.3, 2, or 20 mg/kg SC every 3 days through GD16 in rats and every 2 days through GD19 in rabbits (GD0 was the day of mating). Rats were Caesarean sectioned on GD21, rabbits on GD29., Results: Administration of CNTO 530 was associated with an increase in hematocrit at all dose levels and a decrease in maternal body weight gains. Fetuses exhibited reduced body weight and delayed ossification. Soft tissue changes were limited to cardiovascular alterations in the high-dose rabbits only. Rat and rabbit fetuses were exposed to CNTO 530 in all dose groups., Conclusions: These studies show that the embryo/fetal development effects observed following CNTO 530 treatment during organogenesis are qualitatively similar to those seen with other erythropoietin agonists and are likely a secondary consequence of increased hematocrit in the dams. Unlike other erythropoietin receptor agonists, CNTO 530 was able to cross the placental barrier, which was considered likely the result of FcRn-mediated transcytosis., (2010 Wiley-Liss, Inc.)

Drugs blocking the potassium current IKr of the heart (via hERG channel-inhibition) have the potential to cause hypoxia-related teratogenic effects. However, this activity may be missed in conventional teratology studies because repeat dosing may cause resorptions. The aim of the present study was to investigate an alternative protocol to reveal the teratogenic potential of IKr-blocking drugs. The IKr blocker astemizole, given as a single dose (80 mg/kg) on gestation day (GD) 13 to pregnant rats caused digital defects. In whole rat embryo culture (2h) on GD 13, astemizole caused a decrease in embryonic heart rate at 20 nM, and arrhythmias at 200-400 nM. Cetirizine, without IKr-blocking properties, did not affect the rat embryonic heart in vitro. The present study shows that single dose testing on sensitive days of development, together with whole embryo culture, can be a useful methodology to better characterize the teratogenic potential of IKr-blocking drugs., (Copyright 2010 Elsevier Inc. All rights reserved.)

To explore the predictivity of dose range-finding (DRF) studies, we conducted asurvey by sending out questionnaires to 72 Japanese pharmaceutical companies.The survey yielded data for 108 and 85 compounds for which any embryo-fetaldevelopment (EFD) toxicities were observed in the definitive studies in rodentsand non-rodents, respectively. As a result of the analysis, 83% of studies inrodents and 80% in non-rodents showed EFD effects in the DRF studies. Whenfocusing on teratogenicity, 91% of studies in rodents and 100% in non-rodentswere judged "positive" in the DRF studies when all EFD toxicities were used asmarkers. When the effects of both the rodent and non-rodent studies wereevaluated together, the combination predictive value in the DRF studies was 96%for EFD toxicants and 100% for teratogens. To evaluate the influence of theexamination items, the predictive value was analyzed using 54 compounds forwhich full examinations (external, visceral and skeletal examination) wereconducted in both rodent and non-rodent DRF studies. When the results werejudged by including or excluding skeletal and visceral examinations results,the predictive values were not significantly different. In conclusion, theresults of this survey showed that a pair of the DRF studies in the rodents andnon-rodents is useful to increase the predictivity of DRF studies. In additionthe inclusion of observations such as fetal survival, body weight and externalexamination into the DRF studies are important to predict effects in thedefinitive studies.

The relevance of fetal abnormalities noted at maternally toxic doses is a long-standing issue regarding the interpretation of findings of segment II studies. A number of diseases and conditions during pregnancy are known to adversely affect embryo/fetal development, and along this line many scientists believe that any marked disturbance of maternal homeostasis produced by chemical exposure may eventually produce a teratogenic effect. Although there is little doubt that developmental toxicity may be maternally mediated, the notion that, in principle, any maternal toxicity leads to birth defects is disputed. When embryotoxicity is noted only within the maternally toxic dose range, it is not possible to ascertain whether it is in fact maternally mediated or not (i.e., embryo development may have been impaired by a direct action of the chemical at doses that also adversely affect the mother; in these circumstances it would still be a selective developmental toxicant). However, currently, a chemical is not regarded as a "developmental toxicant" (or "teratogenic agent") if embryotoxicity is apparent only at doses that are also toxic to the mother. In the European Union, developmental hazard identification exerts a strong influence on the classification and labeling of chemicals. In Brazil, registration of any pesticide that proved to be teratogenic in animal studies is strictly forbidden by law (Pesticide Law, Federal Law 7.802, 1989). Therefore, interpretation of findings from developmental toxicity studies in light of maternal toxicity is particularly relevant to regulatory agencies, and becomes even more important when labeling or cutoff decision-making criteria are adopted regarding teratogenicity.

Single oral doses of artesunate, dihydroartemisinin, arteether and artemether administered to rats during a sensitive period of organogenesis caused embryo deaths and malformations (malformed long bones and ventricular septal defects). Extended oral dosing (12 days or more) of monkeys once daily with 12 mg/kg-d artesunate also caused embryo deaths. The initial embryotoxic effect in both species was to kill primitive erythroblasts which are present in the embryo for a few days of gestation in rats and several weeks in primates. The malformations that occurred in rats are attributed to a transient depletion of the primitive erythroblasts. In monkeys, when treatment at 12 mg/kg-d was shortened to 3 or 7 days, the embryos survived but likely suffered a transient loss of primitive erythroblasts. Limited clinical data including 123 first trimester pregnancies have not indicated any adverse effects on pregnancy. However, in rats and monkeys, the embryonic erythroblasts are much more sensitive to artemisinins than are erythroblasts in the adult bone marrow; the latter are indicated by decreases in reticulocyte count. Since decreases in reticulocyte count occur at therapeutic doses in humans, there is reason for concern that any treatment of pregnant women during the putative sensitive period (from approximately postconception Day 21 to approximately postconception week 9) that causes even minor decreases in adult reticulocyte count could also cause a marked depletion of embryonic erythroblasts which could lead to death or malformation of the embryo.

The toxicity of arsenite to 8-cell stage hamster embryos was evaluated. Females were superovulated and mated; embryos were collected and grown for 72 h in culture medium containing vehicle control, 25, 50, 250, 500, or 750 nM arsenite. Morphological observations were taken at 0 and 24h increments. A TUNEL assay was used for determining DNA damage. Survival was expressed by the ability to undergo zona escape. The control group had 78% survival and no evidence of deformities. Embryos in the 25, 50 and 250 nM groups had survival rates of 63%, 55% and 27%, respectively. Arsenite exposure caused total embryo lethality, major deformities, complete failure to undergo zona lysis, and significantly higher number of cells with fragmented DNA in embryos at the 500 and 750 nM concentrations. The study underscores the sensitivity of preimplantation stage embryos to the presence of even relatively small amounts of arsenic in luminal fluid.

We developed and optimized a screening procedure, in which zebrafish embryos were explored as a model for the evaluation of the specific embryotoxic and teratogenic potential of chemicals. A selection of known positive (retinoic acid, valproic acid, caffeine, lithium chloride) and negative (glucose, saccharin) compounds for developmental toxicity were used to evaluate this method. We exposed embryos and evaluated embryotoxicity and morphological characteristics of the embryos at 24, 48, 72 and 144 h post fertilization. After evaluation of the induced effects, concentration-response curves were created for both embryotoxicity and teratogenic effects. Values for teratogenic indices (TI) were calculated as the ratio LC(50)/EC(50). The results obtained were compared to existing data from studies with laboratory animals and humans. We demonstrated that our classification of the compounds, based on TI values, allows to distinguish teratogens from non-teratogens and supports the application of zebrafish embryos as an alternative method for developmental toxicity studies to predict effects in mammals.

Background: Valproic acid (VPA) is used to treat epilepsy and bipolar disorders, as well as for migraine prophylaxis. However, its clinical use is limited by two life-threatening side effects: hepatotoxicity and teratogenicity. To develop a more potent and safer second-generation VPA drug, the urea derivatives of four VPA analogs (2-ethyl-3-methylpentanoyl urea, 2-ethylhexanoyl urea, 2-ethyl-4-methylpentanoyl urea, and 2-methylbutanoyl urea) were synthesized., Methods: Four CNS-active analogs of a VPA urea derivative testedthe anticonvulsant activity in the maximal electroshock seizure test (MES) and subcutaneous metrazol seizure threshold test (scMet). Teratogenic effects of these compounds were evaluated in NMRI mice susceptible to VPA-induced teratogenicity by comparison with VPA., Results: All four VPA analogs showed superior anticonvulsant activity over VPA. Compared with VPA, which induced neural tube defects (NTDs) in fetuses at 1.8 and 3.6 mmol/kg, the analog derivatives induced no NTDs at any concentration up to 4.8 mmol/kg (except for a single abnormality at 3.6 mmol/kg with 2-ethyl-3-methylpentanoyl urea). Skeletal examination also revealed that the acylurea derivatives induced vertebral and rib abnormalities in fetuses markedly less frequently than VPA. Our results confirmed that the analogue derivatives are significantly less teratogenic than VPA in NMRI mice., Conclusions: The CNS-active VPA analogs containing a urea moiety, which have better anticonvulsant potency and lack teratogenicity, are good potential candidates as second-generation VPA antiepileptic drugs., ((c) 2009 Wiley-Liss, Inc.)

As the primary source for regulatory developmental toxicity information, prenatal studies characterize maternal effects and fetal endpoints including malformations, resorptions, and fetal weight reduction. Results from 383 rat and 368 rabbit prenatal studies on 387 chemicals, mostly pesticides, were entered into the U.S. Environmental Protection Agency's (EPA) Toxicity Reference Database (ToxRefDB) using harmonized terminology. An initial assessment of these data was performed with the goal of profiling environmental chemicals based on maternal and fetal endpoints for anchoring in vitro data provided in the EPA's ToxCast research program. Using 30 years worth of standard prenatal studies, maternal and fetal effects were culled from the database and analyzed by target-description fields and lowest effect levels (LELs). Focusing on inter-species comparison, the complexity of fetal target organ response to maternal dosing with environmental chemicals during the period of major organogenesis revealed hierarchical relationships. Of 283 chemicals tested in both species, 53 chemicals (18.7%) had LELs on development (dLEL) that were either specific, with no maternal toxicity (mLEL), or sensitive (dLEL