Teratology

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BACKGROUND: Previous studies observed that retinoic acid receptor-gamma (RARgamma) is expressed in the open caudal neuroepithelium but that RARbeta is expressed in the closed neural tube. Furthermore, retinoic acid (RA) induces RARbeta expression, a molecular event associated with neural tube closure, but treatment with RA at the appropriate gestation time causes failure of neural tube closure. Since there are four isoforms of RARbeta, perhaps the isoforms expressed in the closed neural tube and induced by RA are different...

BACKGROUND: Although previous studies provide some evidence that timing of prenatal care initiation is associated with risks of congenital malformation, the issue has not previously been examined in depth. This study uses data from a large population-based registry to explore the association of timing of prenatal care initiation with risks of selected congenital malformation phenotypes. METHODS: Data on cases were grouped according to four-digit malformation codes of the International Classification of Diseases, Ninth Revision (ICD-9)...

BACKGROUND: Presently, bone ossification is assessed by the study of single-stained fetal bones (alizarin red-S) or double-stained bones and cartilaginous structures (alcian blue followed by alizarin red-S). Both methods, especially double-staining, are labor-intensive, time-consuming, and provide qualitative information regarding skeleton ossification. Quantitative evaluation of ossification is more difficult and is usually based on determination of calcium and other minerals in the bone by means of atomic absorption spectrometry...

BACKGROUND: Hormesis is being recognized in the field of toxicology due to the stimulating effects of some toxic compounds at low exposure levels. Therefore, it is desirable that experimental designs for toxicological studies be flexible enough to aid in the detection of hormetic effects. Current designs may still not have enough power to do this. METHODS: A simulation study was conducted to determine teratological study designs that would yield more power over standard designs in detecting hormesis...

BACKGROUND: Systemic lupus erythematosus (SLE) with or without evidence of antiphospholipid antibodies (aPA) and antiphospholipid syndrome (APS) is associated with a high rate of spontaneous abortions. The placenta is thought to be the site of pathological damage in many of these abortions. To test this hypothesis, we studied the effects of sera obtained from women with SLE with or without treatment on human placental explants in culture. METHODS: We cultured 5...

BACKGROUND: Caspases play a pivotal role in the regulation and execution of apoptosis, an essential process during limb development. Caspase 8 activation is usually downstream of the Fas/FasL death receptors, whereas caspase 9 mediates the mitochondrial signaling pathway of apoptosis. Caspase 3 is an effector caspase. Previous studies have shown that the exposure of embryonic murine limbs in vitro to 4-hydroperoxycyclophosphamide (4-OOHCPA), an activated analog of the anticancer alkylating agent, cyclophosphamide, induced limb malformations and apoptosis...

BACKGROUND: We present a case of partial facial duplication in a male infant. METHODS: The clinical, radiological, and laboratory findings for this patient are described, followed by a review of the literature. RESULTS: Craniofacial duplication is a rare form of conjoined twinning and presents in a wide spectrum, from dicephalus to diprosopus to partial facial duplication. Many of these cases can be diagnosed prenatally. Prenatal assessment of our patient revealed only agenesis of the corpus callosum...

BACKGROUND: The etiology of monozygotic twinning is not known. Some investigators have implicated abnormal X-inactivation, which could also be related to the increased female:male ratio in higher order multiple gestations in general, and in monozygotic and conjoined twins (CTS) in particular. CTS are rare, and even more unusual when part of a triplet pregnancy. METHODS: DNA polymorphism analysis using 13 markers in the buccal cells of the triplets and the lymphocytes of the parents were used to evaluate zygosity...

No abstract text is available yet for this article.

No abstract text is available yet for this article.

BACKGROUND: Glucose metabolites can be detected in embryonic mouse tissues using 13C-NMR spectroscopy. The advantage of this method is in its chemical specificity and the ability to follow metabolic changes. METHODS: In this study, CD-1 mice were mated and embryos excised on gestational day (GD) 10.5 (plug = GD 0.5). Hearts were isolated and cultured in 150 mg/dl glucose (normoglycemic medium) or 40 mg/dl glucose (hypoglycemic medium) for 6 hr. 13C-labeled glucose comprised 62%-64% of total glucose in the culture medium...

BACKGROUND: Orofacial clefts and spina bifida are midline defects with a multifactorial etiology. Maternal smoking and medication use periconceptionally have been studied as risk factors for these malformations. The biotransformation enzyme N-acetyltransferase 2 (NAT2), plays a part in the inactivation of toxic compounds in cigarette smoke and medication. We investigated maternal NAT2 phenotype and the interaction with smoking and medication use periconceptionally on orofacial cleft and spina bifida risk in offspring...

BACKGROUND: Altered cholesterol metabolism and defects in cholesterol biosynthesis may influence abnormal central nervous system (CNS) development. During early stages of embryonic development, high levels of cholesterol are needed by rapidly proliferating cells that utilize cholesterol as a key cell membrane component. Alterations in cholesterol levels are influenced by variations in the apolipoprotein E (apoE) and apolipoprotein B (apoB) genes. The purpose of our study was to explore the possible association between infant genetic variations in the apoE and apoB genes and spina bifida (SB) risk...

BACKGROUND: Nuevo León is a state in northeastern Mexico, near the border of Texas. Mean mortality rate from 1996-98 due to anencephaly cases was 0.6/1,000. In 1999 a surveillance program for the registry and prevention of neural tube defects (NTD) cases was initiated. METHODS: Cases were obtained from hospitals and OB-GYN clinics by immediate notification, death certificates, or fetal death registries. Only isolated cases of NTD were included. In August 1999 a folic acid campaign was initiated with the free distribution of the vitamin to low-income women with a recommendation to take a 5...

BACKGROUND: The purpose of this study is to obtain information on potential familial and environmental risk factors for liveborn cases of heart disease associated with abnormal visceral and vascular sidedness, heterotaxy heart disease, so that hypotheses about this congenital cardiovascular malformation (CCVM) and its risk factors can be generated. We describe the characteristics of infants with heterotaxy heart malformations and case-control comparisons of interview data obtained on parental socio-demographic characteristics, occupational and household environmental exposures...

BACKGROUND: The period of neurogenesis represents a window of susceptibility for in utero methylmercury (MeHg) exposure. This study examined the toxicokinetics of potentially neurotoxic doses of MeHg during neurogenesis in the developing rat to provide additional information in the areas of mercury speciation and inter-study variability. METHODS: Pregnant Sprague-Dawley rats were dosed s.c. with 5-22 mg/kg MeHg on Day 11 of gestation to target rapidly dividing cells of the developing midbrain...

BACKGROUND: Phocomelia, which is primarily due to a disruption in the proximodistal axis, is found in virtually all mouse embryos exposed to high doses of retinoic acid (RA) on 11 days post coitum (dpc). METHODS: To identify genes that potentially mediate the effects of retinoic acid (RA) on limb development, we have examined the expression of 9,000 clones from the IMAGE consortium by microarray analysis of RNA isolated from 11 dpc mouse forelimbs exposed to RA or vehicle for 6 hr...

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BACKGROUND: There is evidence that late birth order is associated with some complex disorders. For orofacial clefts there is no consensus as to whether increased birth order is associated or not. A meta-analysis of published data on cleft lip or cleft palate (CL/P and CP) was carried out to ascertain whether there is an increased risk for children of high birth order to have an oral cleft. METHODS: All data available with information regarding the frequency of live births and CL/P and CP cases by birth order (1, 2, 3, and 4 or more) were included in the analysis, and the birth order category "1" was considered to be with no risk (OR = 1...