Teratogenic Mechanisms Research Articles

The mediating role of abnormal ZEB1 methylation in the association between nickel exposure and non-syndromic orofacial cleft

Our previous study found a positive relationship between fetal nickel exposure and the risk of OFCs. The teratogenic mechanism of nickel is not clear. In this study, we aim to examine the mediating effect of DNA methylation on the association of nickel(Ni) exposure with NSOFC in fetuses. 10 cases and 10 controls was used for screening target gene by Illumina Infinium Methylation EPIC(850k) BeadChip. 36 cases and 78 controls was conducted to determine DNA methylation level of selected gene in umbilical cord blood by Mass spectrometry assay. Mediation analysis was used to evaluate the potential mediating effect of selected gene methylation on the relation between concentrations of Ni and the risk for NSOFC. In the discovery stage, ZEB1 gene was identified to be hypermethylated in both nickel exposure and NSOFC group for validation. In the verification stage, the overall average methylation level of ZEB1 was significant higher in NSOFC cases(median = 8.70, interquartile range(IQR): 5.75–11.53) as compared to controls (median = 5.35, IQR: 4.30–7.78). The risk for NSOFC was increased by 1.43-fold with hypermethylation of ZEB1. Significant correlation was observed between concentrations of Ni in umbilical cord and methylation level of ZEB1. The hypermethylation of ZEB1 had a mediating effect by 20.47 % of total effect of Ni on NSOFC risk. Hypermethylation of ZEB1 is associated with the risk for NSOFC and may partially explain the association between Ni exposure and NSOFC risk. Our findings provide new insights into the epigenetic mechanisms underlying NSOFC and suggesting potential targets for future therapeutic interventions.

Possible New Candidates Involved to Thalidomide-Related Limbs and Cardiac Defects: A Systems Biology Approach.

Thalidomide is a known teratogen that causes malformations especially in heart and limbs. Its mechanism of teratogenicity is still not fully elucidated. Recently, a new target of thalidomide was described, TBX5, and was observed a new interaction between HAND2 and TBX5 that is disrupted in the presence of thalidomide. Therefore, our study aimed to raise potential candidates for thalidomide teratogenesis, through systems biology, evaluating HAND2 and TBX5 interaction and heart and limbs malformations of thalidomide. Genes and proteins related to TBX5 and HAND2 were selected through TF2DNA, REACTOME, Human Phenotype Ontology, and InterPro databases. Networks were assembled using STRING © database. Network analysis were performed in Cytoscape © and R v3.6.2. Differential gene expression (DGE) analysis was performed through gene expression omnibus. We constructed a network for HAND2 and TBX5 interaction; a network for heart and limbs malformations of TE; and the two joined networks. We observed that EP300 protein seemed to be important in all networks. We also looked for proteins containing C2H2 domain in the assembled networks. ZIC3, GLI1, GLI3, ZNF148, and PRDM16 were the ones present in both heart and limbs malformations of TE networks. Furthermore, in the DGE analysis after treatment with thalidomide, we observed that FANCB, ESCO2, and XRCC2 were downregulated and present both in heart and limbs networks. Through systems biology, we were able to point to different new proteins and genes, and selected specially EP300, which was important in all the analyzed networks, to be further evaluated in the TE teratogenicity.

Exploration of Teratogenic Effects of Bambusa vulgaris on Wistar Rats by Evaluating Morphological and Skeletal Parameters

AbstractBambusa vulgaris is a commonly consumable plant, which is widely utilized by indigenous peoples as a source of food. Consumption of these plant products in various forms is typically acceptable due to their distinct tastes, and aromatic flavor. However, there is little information on the plant's safety and toxicity profile. Although toxicity information on B. vulgaris is readily available, the impact of plants during pregnancy has yet to be fully explored. To determine the possible mechanism behind teratogenicity, pregnant albino Wistar rats are administered aqueous extracts of B. vulgaris in a dose‐dependent manner. For determining the structural malformations, Teratogenicity indices include maternal common physiological parameters, number of implantations and fetal indices, number of live, resorpsed, and dead somites, morphological malformations, and skeletal malformations of different organs are evaluated by comparing different test groups with control groups. Most developmental indices, including implantation and fetalindices, vertebral, organ, and skeletal structures are significantly altered by the crude extract at higher dosages in treated as compared to control animals. The administration of aqueous extract of B. vulgaris during the organogenesis phase in rats has a considerable deleterious effect on embryonic and fetal developmental indices. It ruthlessly impacts the embryo's numerous organs as well as their typical physiological processes in a dose‐dependent way. The present investigation validates the capacity of B. vulgaris to cause developmental toxicity in Wistar rats, as evidenced by significant alterations in their gestational morphological, structural, and skeletal anatomy and physiology. It is recommended that further scientific studies be conducted to evaluate the more advanced mechanisms of teratogenicity associated with B. vulgaris.

Arboviruses and pregnancy: are the threats visible or hidden?

Mosquito-borne arboviral diseases are a global concern and can have severe consequences on maternal, neonatal, and child health. Their impact on pregnancy tends to be neglected in developing countries. Despite hundreds of millions of infections, 90% pregnancies being exposed, scientific data on pregnant women is poor and sometimes non-existent. Recently and since the 2016 Zika virus outbreak, there has been a newfound interest in these diseases. Through various neuropathogenic, visceral, placental, and teratogenic mechanisms, these arbovirus infections can lead to fetal losses, obstetrical complications, and a wide range of congenital abnormalities, resulting in long-term neurological and sensory impairments. Climate change, growing urbanization, worldwide interconnectivity, and ease of mobility allow arboviruses to spread to other territories and impact populations that had never been in contact with these emerging agents before. Pregnant travelers are also at risk of infection with potential subsequent complications. Beyond that, these pathologies show the inequalities of access to care on a global scale in a context of demographic growth and increasing urbanization. It is essential to promote research, diagnostic tools, treatments, and vaccine development to address this emerging threat.Background The vulnerability of pregnant women and fetuses to emergent and re-emergent pathogens has been notably illustrated by the outbreaks of Zika virus. Our comprehension of the complete scope and consequences of these infections during pregnancy remains limited, particularly among those involved in perinatal healthcare, such as obstetricians and midwives. This review aims to provide the latest information and recommendations regarding the various risks, management, and prevention for pregnant women exposed to arboviral infections.

Maternal Diabetes and Overweight and Congenital Heart Defects in Offspring

Maternal diabetes and overweight or obesity are known to be associated with increased risk of congenital heart defects (CHDs) in offspring, but there are no large studies analyzing outcomes associated with these factors in 1 model. To investigate the association of maternal diabetes and overweight or obesity with CHDs among offspring in 1 model. This nationwide, population-based register study was conducted in a birth cohort from Finland consisting of all children born between 2006 and 2016 (620 751 individuals) and their mothers. Data were analyzed from January 2022 until November 2023. Maternal prepregnancy body mass index (BMI; calculated as weight in kilograms divided by height in meters squared), categorized as underweight (<18.5), normal (18.5-24.9), overweight (25.0-29.9), and obesity (≥30), was assessed. Maternal diabetes status, classified as no diabetes, type 1 diabetes (T1D), type 2 or other diabetes, and gestational diabetes, was assessed. Odds ratios (ORs) of isolated CHDs in children were found. In addition, 9 anatomical CHD subgroups were studied. Of 620 751 children (316 802 males [51.0%]; 573 259 mothers aged 20-40 years [92.3%]) born in Finland during the study period, 10 254 children (1.7%) had an isolated CHD. Maternal T1D was associated with increased odds of having a child with any CHD (OR, 3.77 [95% CI, 3.26-4.36]) and 6 of 9 CHD subgroups (OR range, 3.28 [95% CI, 1.55-6.95] for other septal defects to 7.39 [95% CI, 3.00-18.21] for transposition of great arteries) compared with no maternal diabetes. Maternal overweight was associated with left ventricular outflow tract obstruction (OR, 1.28 [95% CI, 1.10-1.49]) and ventricular septal defects (OR, 0.92 [95% CI, 0.86-0.98]), and obesity was associated with complex defects (OR, 2.70 [95% CI, 1.14-6.43]) and right outflow tract obstruction (OR, 1.31 [95% CI, 1.09-1.58]) compared with normal maternal BMI. This study found that maternal T1D was associated with increased risk for most types of CHD in offspring, while obesity and overweight were associated with increased risk for complex defects and outflow tract obstruction and decreased risk for ventricular septal defects. These different risk profiles of T1D and overweight and obesity may suggest distinct underlying teratogenic mechanisms.

Valproic Acid in Pregnancy Revisited: Neurobehavioral, Biochemical and Molecular Changes Affecting the Embryo and Fetus in Humans and in Animals: A Narrative Review.

Valproic acid (VPA) is a very effective anticonvulsant and mood stabilizer with relatively few side effects. Being an epigenetic modulator, it undergoes clinical trials for the treatment of advanced prostatic and breast cancer. However, in pregnancy, it seems to be the most teratogenic antiepileptic drug. Among the proven effects are congenital malformations in about 10%. The more common congenital malformations are neural tube defects, cardiac anomalies, urogenital malformations including hypospadias, skeletal malformations and orofacial clefts. These effects are dose related; daily doses below 600 mg have a limited teratogenic potential. VPA, when added to other anti-seizure medications, increases the malformations rate. It induces malformations even when taken for indications other than epilepsy, adding to the data that epilepsy is not responsible for the teratogenic effects. VPA increases the rate of neurodevelopmental problems causing reduced cognitive abilities and language impairment. It also increases the prevalence of specific neurodevelopmental syndromes like autism (ASD) and Attention Deficit Hyperactivity Disorder (ADHD). High doses of folic acid administered prior to and during pregnancy might alleviate some of the teratogenic effect of VPA and other AEDs. Several teratogenic mechanisms are proposed for VPA, but the most important mechanisms seem to be its effects on the metabolism of folate, SAMe and histones, thus affecting DNA methylation. VPA crosses the human placenta and was found at higher concentrations in fetal blood. Its concentrations in milk are low, therefore nursing is permitted. Animal studies generally recapitulate human data.

Common teratogenic medication exposures—a population-based study of pregnancies in the United States

BackgroundRisk mitigation for most teratogenic medications relies on risk communication via drug label, and prenatal exposures remain common. Information on the types of and risk factors for prenatal exposures to medications with teratogenic risk can guide strategies to reduce exposures. ObjectivesTo identify medications with known or potential teratogenic risk commonly used during pregnancy among privately insured persons. Study DesignWe used MarketScan® Commercial Claims and Encounters Data to identify pregnancy episodes with live or non-live (ectopic pregnancies, spontaneous and elective abortions, stillbirths) outcomes among persons aged 12 to 55 years during 2011-2018. Start/end dates of medication exposure and pregnancy outcomes were identified via an adapted algorithm based on validation studies. We required continuous health plan enrollment from 90 days before conception until 30 days after pregnancy end date. Medications with known or potential teratogenic risk were selected from the Teratogen Information System (TERIS) and drug monographs based on the level of risk and quality of evidence (138 with known and 60 with potential risk). We defined prenatal exposure based on ≥1 outpatient pharmacy claim or medical encounter for drug administration during target pregnancy periods considering drug risk profiles (e.g., risk only in the first trimester or at a certain dose threshold). Sex hormones and hormone analogs, abortion and post-partum/abortion hemorrhage treatments were not considered as teratogenic medications because of challenges to separate pregnancy-related indications, nor were opioids (due to complex risk-benefit) or anti-obesity drugs if their only teratogenic mechanism was weight loss. ResultsAmong all pregnancies, the 10 medications with known teratogenic risk and with the highest prenatal exposures were sulfamethoxazole/trimethoprim (SMX/TMP) (1,988 per 100,000 pregnancy years), high-dose fluconazole (1248), topiramate (351), lisinopril (144), warfarin (57), losartan (56), carbamazepine (50), valproate (49), vedolizumab (28 since 2015), and valsartan (25). Exposure prevalence to SMX/TMP decreased from 2,346 to 1,453 per 100,000 pregnancy years during 2011 – 2018, but exposure prevalence to vedolizumab increased sixfold since its approval in 2015. Prenatal exposures in the first trimester among non-live pregnancies were higher compared to live-birth pregnancies, with the largest difference for warfarin (non-live 370 vs. live-birth 78), followed by valproate (258 vs. 86) and topiramate (1,728 vs. 674). Prenatal exposures to medications with potential teratogenic risk were most prevalent for low-dose fluconazole (6,495), metoprolol (1,325) and atenolol (448). The largest first-trimester exposure differences between non-live and live-birth pregnancies were for lithum (242 vs. 89), gabapentin (1,639 vs. 653), and duloxetine (1,914 vs. 860). Steady increases in hydralazine and gabapentin exposures were seen during study years, while atenolol exposures decreased (561 to 280). ConclusionsSeveral medications with teratogenic risk for which there are potentially safer alternatives continue to be used during pregnancy. The fluctuating rates of prenatal exposure observed in select teratogenic medications suggest regular reevaluation of risk mitigation strategies is needed. Future research focusing on understanding the clinical context of medication use is necessary to develop effective strategies for reducing exposures to medications with teratogenic risk during pregnancy.

Identification of an adverse outcome pathway (AOP) for chemical-induced craniofacial anomalies using the transgenic zebrafish model.

Craniofacial anomalies are one of the most frequent birth defects worldwide and are often caused by genetic and environmental factors such as pharmaceuticals and chemical agents. Although identifying adverse outcome pathways (AOPs) is a central issue for evaluating the teratogenicity, the AOP causing craniofacial anomalies has not been identified. Recently, zebrafish has gained interest as an emerging model for predicting teratogenicity because of high throughput, cost-effectiveness and availability of various tools for examining teratogenic mechanisms. Here, we established zebrafish sox10-EGFP reporter lines to visualize cranial neural crest cells (CNCCs) and have identified the AOPs for craniofacial anomalies. When we exposed the transgenic embryos to teratogens that were reported to cause craniofacial anomalies in mammals, CNCC migration and subsequent morphogenesis of the first pharyngeal arch were impaired at 24 hours post-fertilization. We also found that cell proliferation and apoptosis of the migratory CNCCs were disturbed, which would be key events of the AOP. From these results, we propose that our sox10-EGFP reporter lines serve as a valuable model for detecting craniofacial skeletal abnormalities, from early to late developmental stages. Given that the developmental process of CNCCs around this stage is highly conserved between zebrafish and mammals, our findings can be extrapolated to mammalian craniofacial development and thus help in predicting craniofacial anomalies in human.

A Shared Pathogenic Mechanism for Valproic Acid and SHROOM3 Knockout in a Brain Organoid Model of Neural Tube Defects.

Neural tube defects (NTDs), including anencephaly and spina bifida, are common major malformations of fetal development resulting from incomplete closure of the neural tube. These conditions lead to either universal death (anencephaly) or severe lifelong complications (spina bifida). Despite hundreds of genetic mouse models of neural tube defect phenotypes, the genetics of human NTDs are poorly understood. Furthermore, pharmaceuticals, such as antiseizure medications, have been found clinically to increase the risk of NTDs when administered during pregnancy. Therefore, a model that recapitulates human neurodevelopment would be of immense benefit to understand the genetics underlying NTDs and identify teratogenic mechanisms. Using our self-organizing single rosette cortical organoid (SOSR-COs) system, we have developed a high-throughput image analysis pipeline for evaluating the SOSR-CO structure for NTD-like phenotypes. Similar to small molecule inhibition of apical constriction, the antiseizure medication valproic acid (VPA), a known cause of NTDs, increases the apical lumen size and apical cell surface area in a dose-responsive manner. GSK3β and HDAC inhibitors caused similar lumen expansion; however, RNA sequencing suggests VPA does not inhibit GSK3β at these concentrations. The knockout of SHROOM3, a well-known NTD-related gene, also caused expansion of the lumen, as well as reduced f-actin polarization. The increased lumen sizes were caused by reduced cell apical constriction, suggesting that impingement of this process is a shared mechanism for VPA treatment and SHROOM3-KO, two well-known causes of NTDs. Our system allows the rapid identification of NTD-like phenotypes for both compounds and genetic variants and should prove useful for understanding specific NTD mechanisms and predicting drug teratogenicity.

The inter- and multi- generational epigenetic alterations induced by maternal cadmium exposure.

Exposure to cadmium during pregnancy, from environmental or lifestyle factors, has been shown to have detrimental fetal and placental developmental effects, along with negatively impacting maternal health during gestation. Additionally, prenatal cadmium exposure places the offspring at risk for developing diseases in infancy, adolescence, and adulthood. Although given much attention, the underlying mechanisms of cadmium-induced teratogenicity and disease development remain largely unknown. Epigenetic changes in DNA, RNA and protein modifications have been observed during cadmium exposure, which implies a scientific premise as a conceivable mode of cadmium toxicity for developmental origins of health and disease (DOHaD). This review aims to examine the literature and provide a comprehensive overview of epigenetic alterations induced by prenatal cadmium exposure, within the developing fetus and placenta, and the continued effects observed in childhood and across generations.

Using Rabbit Induced Pluripotent Stem Cell-Derived Cardiomyocytes to Investigate Drug-Induced Fetal Heart Malformations

Introduction: Teratogenic events such as fetal heart malformations are serious and tragic drug-induced toxicities. Preclinical studies conducted during drug safety evaluation are intended to identify teratogenic risks using rodent and nonrodent models, largely based on the experience with thalidomide, which is teratogenic in humans and rabbits but refractory in rodents. Methods: To study the teratogenic properties of thalidomide in rabbit, a novel method was designed to develop cardiomyocytes (CMs) from rabbit induced pluripotent stem cells (rbiPSCs). Throughout the course of differentiation, rbiPSC-CMs were examined by real time polymerase chain reaction, high-content analysis, calcium flux measurements, and electrophysiology to confirm the cell's mature CM phenotype. The effects of thalidomide were then measured in each of the endpoints when present throughout differentiation. Results: As early as differentiation day (DD) 3 of the differentiation, rbiPSCs begin to express early CM markers (e.g., NXK2.5) and mesodermal markers (e.g., FOXF1). By DD 21, rbiPSC-CMs expressed messenger RNA (mRNA) and protein of mature CM genes, including TNNT2, HCN4, and KCNJ2. Spontaneous beating was observed by microscopy and electrophysiology as early as DD 8, and live cell calcium probes demonstrated pulsatile calcium flux. Thalidomide treatment to rbiPSC-CMs downregulated mRNA and protein of early and mature cardiac markers, suggesting suppressed differentiation. In addition, thalidomide treatment abrogated the onset of spontaneously beating cells. Conclusions: Taken together, these data indicate that rbiPSC-CMs can recapitulate thalidomide-induced cardiac teratogenicity observed in rabbits. Moving forward, this model can be deployed to investigate the underlying mechanisms of rabbit teratogenicity and better understand species-specific differences in drug-induced fetal heart malformations.

Cell type-specific changes in Wnt signaling and neuronal differentiation in the developing mouse cortex after prenatal alcohol exposure during neurogenesis.

Fetal Alcohol Spectrum Disorder (FASD) encompasses an array of effects of prenatal alcohol exposure (PAE), including physical abnormalities and cognitive and behavioral deficits. Disruptions of cortical development have been implicated in multiple PAE studies, with deficits including decreased progenitor proliferation, disrupted neuronal differentiation, aberrant radial migration of pyramidal neurons, and decreased cortical thickness. While several mechanisms of alcohol teratogenicity have been explored, how specific cell types in the brain at different developmental time points may be differentially affected by PAE is still poorly understood. In this study, we used single nucleus RNA sequencing (snRNAseq) to investigate whether moderate PAE from neurulation through peak cortical neurogenesis induces cell type-specific transcriptomic changes in the developing murine brain. Cluster analysis identified 25 neuronal cell types, including subtypes of radial glial cells (RGCs), intermediate progenitor cells (IPCs), projection neurons, and interneurons. Only Wnt-expressing cortical hem RGCs showed a significant decrease in the percentage of cells after PAE, with no cell types showing PAE-induced apoptosis as measured by caspase expression. Cell cycle analysis revealed only a subtype of RGCs expressing the downstream Wnt signaling transcription factor Tcf7l2 had a decreased percentage of cells in the G2/M phase of the cell cycle, suggesting decreased proliferation in this RGC subtype and further implicating disrupted Wnt signaling after PAE at this early developmental timepoint. An increased pseudotime score in IPC and projection neuron cell types indicated that PAE led to increased or premature differentiation of these cells. Biological processes affected by PAE included the upregulation of pathways related to synaptic activity and neuronal differentiation and downregulation of pathways related to chromosome structure and the cell cycle. Several cell types showed a decrease in Wnt signaling pathways, with several genes related to Wnt signaling altered by PAE in multiple cell types. As Wnt has been shown to promote proliferation and inhibit differentiation at earlier stages in development, the downregulation of Wnt signaling may have resulted in premature neuronal maturation of projection neurons and their intermediate progenitors. Overall, these findings provide further insight into the cell type-specific effects of PAE during early corticogenesis.

Final results from the ribavirin pregnancy registry, 2004-2020.

Significant teratogenic effects have been demonstrated for ribavirin in animal studies. Ribavirin is prescribed for chronic hepatitis C and is contraindicated in pregnant women and their male sexual partners. Both are advised to avoid pregnancy for 6months after exposure. The registry monitored pregnancy exposures to oral formulations of ribavirin for hepatitis C for signals of possible human teratogenicity from 2004 to 2020. Pregnant women were voluntarily enrolled following direct exposure (ribavirin use during pregnancy or the 6months prior) or indirect exposure (through sexual contact during pregnancy or 6months prior, with a man who has taken ribavirin within 6months). Women were followed until the end of pregnancy. Infants were followed until 1year of age. Birth defect rates were compared with the published rate of 2.67 per 100 live births from the Metropolitan Atlanta Congenital Defects Program (MACDP). The registry enrolled 280 pregnancies resulting in 186 live births: eight birth defect cases among 88 directly exposed [9.09% (8/88, 95% CI: 4.01, 17.13)], and six birth defect cases among 98 indirectly exposed [6.12% (6/98, 95% CI: 2.28, 12.85)]. The 95% CI around the birth defect rate among directly exposed pregnancies exceeds the MACDP rate; however, no patterns suggestive of a teratogenic mechanism or safety signal were detected. Based on the patterns of birth defects reported, the final results from this registry do not suggest a clear signal of human teratogenicity for ribavirin. The registry did not meet sample size requirements; therefore, caution should be exercised when interpreting the results.

The pro-apoptotic Bax gene modifies susceptibility to craniofacial dysmorphology following gastrulation-stage alcohol exposure.

During early development, alcohol exposure causes apoptotic cell death in discrete regions of the embryo which are associated with distinctive patterns of later-life abnormalities. In gastrulation, which occurs during the third week of human pregnancy, alcohol targets the ectoderm, the precursor of the eyes, face, and brain. This midline tissue loss leads to the craniofacial dysmorphologies, such as microphthalmia and a smooth philtrum, which define fetal alcohol syndrome (FAS). An important regulator of alcohol-induced cell death is the pro-apoptotic protein Bax. The current study determines if mice lacking the Bax gene are less susceptible to the pathogenic effects of gastrulation-stage alcohol exposure. Male and female Bax+/- mice mated to produce embryos with full (-/- ) or partial (+/- ) Bax deletions, or Bax+/+ wild-type controls. On Gestational Day 7 (GD 7), embryos received two alcohol (2.9g/kg, 4 hr apart), or control exposures. A subset of embryos was collected 12 hr later and examined for the presence of apoptotic cell death, while others were examined on GD 17 for the presence of FAS-like facial features. Full Bax deletion reduced embryonic apoptotic cell death and the incidence of fetal eye and face malformations, indicating that Bax normally facilitates the development of alcohol-induced defects. An RNA-seq analysis of GD 7 Bax+/+ and Bax-/- embryos revealed 63 differentially expressed genes, some of which may interact with the Bax deletion to further protect against apoptosis. Overall, these experiments identify that Bax is a primary teratogenic mechanism of gastrulation-stage alcohol exposure.

Genetic Aspects in Congenital Heart Diseases in Infant of Diabetic Mother: A Review Article

Background: The pathogenesis and effects of maternal diabetes on their infants is still not entirely understood, but it's likely to have several teratogenic mechanisms. The fetal heart is anatomically and physiologically altered by diabetes mellitus. About 400 genes are thought to be involved in the etiology of congenital heart disease such as DAW1, DNAI1,DRC1, PDE2A,CCDC39,TMEM67, and ICAM. Endothelial cells and immune system cells exhibit the cell surface glycoprotein CD54, also known as intercellular adhesion mollecule-1 (ICAM-1), which is thought to contribute to atherogenesis by increasing monocyte accumulation within the artery intima. In adult individuals with unexplained cardiac dysfunction as well as animals with myocarditis, ICAM-1 expression has been seen on cardiac myocytes. So, the aim of our review is to explore variant genetic aspects implicated in development of congenital heart diseases (CHD) in infants of diabetic mothers and the possible effect of diabetes mellitus.&#x0D; Conclusion: Genes that were highly enriched in cell adhesion molecules (CAMs) were found to be among the many differentially expressed genes (DEGs) in embryonic heart tissues from diabetic mothers, including ICAM-1, which had the greatest connection degree in the protein-protein interaction (PPI) of both upregulated DEGs and shared DEGs and are major determinants in development of CHD among infant born to diabetic mothers.

From the Farm to the Lab: How Chicken Embryos Contribute to the Field of Teratology.

Congenital anomalies and its causes, particularly, by external factors are the aim of the field called teratology. The external factors studied by teratology are known as teratogens and can be biological or environmental factors for example, chemicals, medications, recreational drugs, environmental pollutants, physical agents (e.g., X-rays and maternal hyperthermia) and maternal metabolic conditions. Proving the teratogenicity of a factor is a difficult task requiring epidemiology studies as well as experimental teratology evidence from the use of animal models, one of which is the chicken embryo. This model in particular has the advantage of being able to follow development live and in vivo, with rapid development hatching around 21 days, is cheap and easy to manipulate and to observe development. All this allows the chicken embryo to be used in drug screening studies, teratogenic evaluation and studies of mechanisms of teratogenicity. The chicken embryo shares morphological, biochemical and genetic similarities with humans as well as mammalian species, making them ideal to ascertain the actions of teratogens, as well as screen drugs to test for their safety. Pre-clinical trials for new drugs are carried out in rodents and rabbits, however, chicken embryos have been used to screen new compounds or analogs of thalidomide as well as to investigate how some drugs can lead to congenital malformations. Indeed, the chicken embryo has proved valuable in understanding how many congenital anomalies, seen in humans, arise following teratogen exposure. The aim of this review is to highlight the role of the chicken embryo as an experimental model for studies in teratology, exploring its use in drug screening studies, phenotypic evaluation and studies of teratogenic mechanisms of action. Here, we discuss many known teratogens, that have been evaluated using the chicken embryo model including some medicines, such as, thalidomide, valproic acid; recreational drugs including alcohol; environmental influences, such as viruses, specifically ZIKV, which is a newly discovered human teratogen. In addition, we discuss how the chicken embryo has provided insight on the mechanisms of teratogenesis of many compounds and also how this impact on drug safety.

Hydrolytic stability of anticancer drugs and one metabolite in the aquatic environment

Due to the genotoxic, carcinogenic and teratogenic mechanism of action, anticancer drugs are highly hazardous compounds. Their occurrence, fate, and effects in the environment have not been systematically studied as compared to other medicaments. Therefore, reliable data, including their stability and persistency, is required in order to assess it. Taking into account, that hydrolysis is one of the most important factors regarding stability of chemicals in water, the aim of our study was to investigate the hydrolytic stability of five commonly used anticancer drugs (ifosfamide, cyclophosphamide, 5-fluorouracil, imatinib, and methotrexate) and one metabolite (7-hydroxymethotrexate), as the systematized and coherent data available is limited. The hydrolysis studies have been prepared according to the OECD 111 procedure to obtain standardized and comparable results. The preliminary tests at pH 4, 7, and 9 and 50 °C show that only cyclophosphamide and ifosfamide are unstable, whereas the estimated t1/2 at 25 °C is >1 year for other investigated compounds. Moreover, much more detailed experiments were performed and indicate that at environmentally relevant temperatures, cyclophosphamide, and ifosfamide would be quite persistent in the terms of hydrolytic stability. Moreover, the preliminary investigation on the hydrolysis products was performed.

Effect of Pethidine Hydrochloride on the Development of Neural Tube: A Genetic Analysis Study in a Chick Embryo Model

Neural tube defects are among the most frequent congenital abnormalities of the central nervous system. Progression of neural tube deficits is affected by hereditary predilection and environmental determinants. Pethidine (meperidine) is a fast and powerful opioid analgesic in U.S. Food and Drug Administration category C. There are reports about developmental anomalies due to this medication. The aim of this study was to investigate the effects of different doses of pethidine hydrochloride on neural tube development in a chick embryo model resembling the first month of vertebral growth in mammals. Seventy-five specific pathogen-free eggs were incubated for 28 hours and divided into 5 groups (including the control group), each consisting of 15 eggs. Pethidine hydrochloride was administered sub-blastodermically with a Hamilton microinjector in 4 different doses. Incubation was continued until the end of the 48th hour. Subsequently, all eggs were opened, and embryos were cut from the embryonic membranes and evaluated morphologically, genetically, and histopathologically. Crown-rump length, somite numbers, and silver-stained nucleolar organizer region (AgNOR) number averages, and total AgNOR/nuclear area ratios decreased in a dose-dependent manner. Examination of neural tube closure revealed statistically significant differences in all experimental groups (P<0.05). Messenger RNA levels of the BRE gene were decreased in pethidine hydrochloride-exposed embryos compared with the control group. Although this downregulation was not statistically significant, this decrease was striking with a 0.422-fold change in the fifth group. We demonstrated that pethidine hydrochloride affects neuronal development in chicken embryos. The teratogenic mechanism of pethidine hydrochloride is unclear; therefore, further investigation is required.

First trimester mechanisms of gestational sac placental and foetal teratogenicity: a framework for birth cohort studies.

The function of the gestational sac (GS) and the placenta in the closely related processes of embryogenesis and teratogenicity in the first trimester has been minimally described. The prevailing assumption is that direct teratogenic effects are mediated by the critical extraembryonic organ, the placenta, which either blocks or transfers exposures to the foetus. Placental transfer is a dominant mechanism, but there are other paradigms by which the placenta can mediate teratogenic effects. Knowledge of these paradigms and first trimester human developmental biology can be useful to the epidemiologist in the conduct of biomarker-based studies of both maternal and child health. Our aim is to provide a causal framework for modelling the teratogenic effects of first trimester exposures on child health outcomes mediated by the GS and placenta using biomarker data collected in the first trimester. We initially present first trimester human developmental biology for the sake of informing and strengthening epidemiologic approaches. We then propose analytic approaches of modelling placental mechanisms by way of causal diagrams using classical non-embryolethal teratogens (diethylstilboestrol [DES], folic acid deficiency and cytomegalovirus [CMV]) as illustrative examples. We extend this framework to two chronic exposures of particular current interest, phthalates and maternal adiposity. Information on teratogens was identified by a non-systematic, narrative review. For each teratogen, we included papers that answered the five following questions: (i) why were these exposures declared teratogens? (ii) is there a consensus on biologic mechanism? (iii) is there reported evidence of a placental mechanism? (iv) can we construct a theoretical model of a placental mechanism? and (v) can this knowledge inform future work on measurement and modelling of placental-foetal teratogenesis? We prioritized literature specific to human development, the organogenesis window in the first trimester and non-embryolethal mechanisms. As a result of our review of the literature on five exposures considered harmful in the first trimester, we developed four analytic strategies to address first trimester placental mechanisms in birth cohort studies: placental transfer and direct effects on the foetus (DES and maternal adiposity), indirect effects through targeted placental molecular pathways (DES and phthalates), pre-placental effects through disruptions in embryonic and extraembryonic tissue layer differentiation (folic acid deficiency), and multi-step mechanisms that involve maternal, placental and foetal immune function and inflammation (DES and CMV). The significance of this review is to offer a causal approach to classify the large number of potentially harmful exposures in pregnancy when the exposure occurs in the first trimester. Our review will facilitate future research by advancing knowledge of the first trimester mechanisms necessary for researchers to effectively associate environmental exposures with child health outcomes.

Anti-epileptic drug topiramate upregulates TGFβ1 and SOX9 expression in primary embryonic palatal mesenchyme cells: Implications for teratogenicity.

Topiramate is an anti-epileptic drug that is commonly prescribed not just to prevent seizures but also migraine headaches, with over 8 million prescriptions dispensed annually. Topiramate use during pregnancy has been linked to significantly increased risk of babies born with orofacial clefts (OFCs). However, the exact molecular mechanism of topiramate teratogenicity is unknown. In this study, we first used an unbiased antibody array analysis to test the effect of topiramate on human embryonic palatal mesenchyme (HEPM) cells. This analysis identified 40 differentially expressed proteins, showing strong connectivity to known genes associated with orofacial clefts. However, among known OFC genes, only TGFβ1 was significantly upregulated in the antibody array analysis. Next, we validated that topiramate could increase expression of TGFβ1 and of downstream target phospho-SMAD2 in primary mouse embryonic palatal mesenchyme (MEPM) cells. Furthermore, we showed that topiramate treatment of primary MEPM cells increased expression of SOX9. SOX9 overexpression in chondrocytes is known to cause cleft palate in mouse. We propose that topiramate mediates upregulation of TGFβ1 signaling through activation of γ-aminobutyric acid (GABA) receptors in the palate. TGFβ1 and SOX9 play critical roles in orofacial morphogenesis, and their abnormal overexpression provides a plausible etiologic molecular mechanism for the teratogenic effects of topiramate.