bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cadherin mRNAs during rat embryo development in vivo and in vitro
Authors: Chen Beiyun , Blaschuk Orest W. , Hales Barbara F. 
Published: June 2005

AbstractWhole rat embryo cultures are being used in increasing numbers of laboratories to study the mechanisms by which teratogens disturb development. The development of early somite stage embryos in vitro is very similar morphologically to that in vivo, yet few biochemical comparisons have been made. The purpose of this study was to determine the steady‐state mRNA concentrations of a family of Ca2+ ‐dependent cell adhesion molecules, the cadherins, during rat embryonic development in vivo and in vitro. Embryos and yolk sacs were collected on days 10, 11, and 12 of gestation (in vivo); they were also obtained from day 10 embryos after growth in culture for 24 hr (day 11 in vitro) or 45 hr (day 12 in vitro). Total RNAs isolated from embryos and yolk sacs were studied by Northern blot analysis using specific cDNA probes for three cadherins, E‐cadherin, N‐cadherin, and P‐cadherin. Although E‐cadherin mRNA was detected in embryos, it was present at much higher concentrations in yolk sacs. In addition, multiple species of E‐cadherin mRNA ranging from 3.0 to 13 kb were detected. Interestingly, the concentration of the major 4.5‐kb E‐cadherin mRNA species in yolk sac after 45 hr in culture was increased 2.8‐fold over that on day 12 of gestation in vivo. Second, two species (4.3 and 3.5 kb) of N‐cadherin mRNA were detected, almost exclusively in embryos. In yolk sac, N‐cadherin mRNA was detected only after 45 hr in culture. Third, P‐cadherin mRNA was detected as a single 3.5‐kb species, mainly in embryos. Pcadherin mRNA concentrations in yolk sac after 45 hr in culture were 5.6‐fold higher than in vivo. Thus, these results demonstrate that there is a differential distribution of cadherin mRNAs in rat embryos and yolk sacs. Further, there appear to be multiple species of mRNAs for E‐cadherin and N‐cadherin. Finally, while whole embryo culture in vitro did not significantly alter the steady‐state concentrations of cadherin mRNAs in the embryo, these concentrations were dramatically increased in the yolk sac.
Effects of isotretinoin (13‐Cis‐retinoic acid) on the development of mouse limbs in vivo and in vitro
Authors: Kwasigroch Thomas E. , Bullen Michael 
Published: June 2005

AbstractIsotretinoin (13‐cis‐RA) is known to be teratogenic in humans and laboratory animals. The relatively low potency of 13‐cis‐RA in NRMI mice in comparison to the all‐trans isomer has been proposed to be due to minimal transfer across the placenta (Creech‐Kraft et al., '87). To further delineate the teratogenic potential of 13‐cis‐RA, a dose‐response, temporal study was conducted in vivo and in vitro using submerged limb culture and image analysis evaluation of development. Dose‐dependent embryotoxicity was produced by treatment on GD 7, while later treatments produced inconsistent effects on resorption rate and fetal weight. Treatment on either GD 7 or GD 8 produced a number of malformations in dose‐dependent manner. Most common were tail and cleft palate defects, which were produced by 13‐cis‐RA on each of the days tested (GD 7–GD 11), with peak malformations occurring on GD 9 and GD 10 for tail and cleft palate, respectively. Most limb defects were produced after GD 10 and GD 11 exposure. The observed frequency of defects confirmed that in ICR mice 13‐cis‐RA is about 10‐fold less potent than all‐trans‐RA as a limb teratogen (Kwasigroch and Kochhar, '80; Kochhar and Penner, '87). Effects observed via image analysis following maintenance of limbs in serum‐free culture medium were dose dependent. Low dose treatment produced occasional polydactyly. The intermediate dose caused somewhat variable region‐dependent increases in cartilaginous bone anlagen area. The high dose of 13‐cis‐RA produced irregular limb outlines, a reduction in bone anlagen area, and an inhibition of alcian blue staining of cartilage without affecting morphogenesis of bone anlagen. These results confirm that, when the effects of the administered doses are evaluated, 13‐cis‐RA is a much less potent teratogen in comparison to the all‐trans isomer. More importantly, the results show that retinoids can enhance (at low and intermediate doses), depress (at high doses), or eliminate (high dose) chondro‐genenic expression during limb morphogenesis in vitro. This indicates that retinoids such as 13‐cis‐RA can manipulate events in development in a variety of ways (i. e., produce malformations, interfere with chondrogenic expression without affecting morphogenesis, and stimulate growth) in a dose‐ and time‐dependent manner. Although the ability of RA to act as a true morphogen has recently been questioned (Wanek et al., '91; Noji et al., '91), the results presented here support the position that RA can modulate the development of the limb (and probably other organ systems) in several vertebrate species.
Parental fertility and infant hypospadias: An international case‐control study
Authors: Källén Bengt , Castilla Eduardo E. , Kringelbach Mette , Lancaster Paul A. L. , Martínez‐Frías Maria Luisa , Mastroiacovo Pierpaolo , Mutchinick Osvaldo , Robert Elisabeth 
Published: June 2005

AbstractThe authors have performed an international case‐control study on the significance of exogenous hormones for the origin of hypospadias (Källén et al., 1991a, b). Using data from this study on 846 infants with isolated hypospadias and equally many controls (next male infant born in the same hospital as the case), variables that might indicate an increased rate of fertility problems in couples who had a boy with hypospadias were studied. Cases had slightly fewer previous pregnancies, there was practically no difference in the rate of previous induced abortions, and no demonstrable difference in menstrual history. Infertility periods of at least 6 months were more likely among cases than controls but the difference did not reach statistical significance in a two‐tailed test. There was no demonstrable difference in the time to conceive between cases and controls. The difficulties of directly studying subfertility problems are stressed.
Teratogenicity of all‐trans retinoic acid during early embryonic development in the cynomolgus monkey (Macaca fascicularis)
Authors: Hendrickx Andrew G. , Hummler Hans 
Published: June 2005

AbstractThe embryotoxic and teratogenic potential of all‐trans retinoic acid was assessed following exposure prior to and during early organogenesis in the cynomolgus monkey (Macaca fascicularis). Sixteen pregnant females were orally administered all‐trans retinoic acid (Tretinoin, Hoffmann‐La Roche) once daily from GD 10–20 and twice daily from GD 21–24 at three different dosages, 5 (n=9), 10 (n=6) and 20 mg/kg (n=1). Adverse clinical signs resembling hypervitaminosis A were observed in one animal at 5 mg/kg, in three animals at 10 mg/kg, and in the animal treated with 20 mg/kg all‐trans retinoic acid. Maternal weight loss was observed in the 10‐ and 20‐mg/kg groups. A dose‐dependent increase in embryolethality was observed, with 22% (2/9), 50% (3/6), and 100% (1/1) occurring at 5, 10, and 20 mg/kg, respectively. The majority of embryonic deaths occurred between GD 16 and 20; the incidence of these early losses was higher than in historical and concurrent controls. No malformations, but a single growth‐retarded fetus, was observed in the 5‐mg/kg group. Craniofacial malformations, consisting of external ear defects, mandibular hypoplasia, cleft palate, and temporal bone abnormalities, were seen in three viable fetuses in the 10‐mg/kg group. Skeletal variations were common to the majority (70%, 7/10) of viable fetuses in both dose groups and were increased relative to historical controls (32%, 25/77). Unlike previous studies with 13‐cis‐retinoic acid during the pre‐ and early organogenic stages of development (Hummler et al., Teratology 42:263‐272, 1990), no thymic hypo‐ or aplasia or heart anomalies were observed, which may be attributable to the slightly longer 13‐cis retinoic acid treatment period, i.e., GD 10–27. However, external ear and temporal bone defects were common to both all‐trans and 13‐cis retinoic acid. The similarity observed in the malformation syndrome induced by both all‐trans and 13‐cis retinoic acid in the cynomolgus monkey and 13‐cis retinoic acid embryopathy in humans supports this macaque species as a model for further developmental toxicity studies of vitamin A‐related compounds.
Aberrant convergence of the neural folds in the mouse mutant vl
Authors: Wilson Doris B. , Wyatt Darlene P. 
Published: June 2005

AbstractProgressive changes in the dorsolateral angles (DA) and ventral angle (VA) during elevation and convergence of the caudal neural folds were morphometrically analyzed in normal and dysraphic abnormal embryos of the mouse mutant vacuolated lens (vl), and correlations with the configuratio of microfilaments in the apices of neuroepithelial cells were made by means of ultrastructural cytochemistry. In 22‐28 somite stage abnormal (vl/vl) embryos, the DA and VA are larger than those in their normal counterparts at each comparable level of the caudal neural folds, suggesting that defective convergence involves both the DA and VA in this mutant. In 30–35 somite stage abnormal embryos, the VA is likewise larger than that in normal embryos in which the neural folds have converged and closed; however, the DAs are much smaller, indicating that a medial collapse of the dorsal ends of the neural folds may occur secondary to the closure failure. At the DA, the ultrastructural configuration of microfilaments is similar in abnormal and normal embryos in terms of their circumferential arrangement around the perimeters of the neuroepithelial cell apices. In abnormal embryos, however, the bundles of microfilaments are more delicate and less prominent than in normal embryos; thus it is possible that a quantitative and/or functional deficiency in these elements may be involved in the failure of the abnormal neuroepithelium to bend properly during convergence of the neural folds.
The use of dysmorphology in birth defects epidemiology
Authors: Friedman J. M. 
Published: June 2005

AbstractMost human teratogens have been identified by the clinical recognition of characteristic patterns of congenital anomalies among children whose mothers were exposed to a particular agent during pregnancy. Although this dysmorphologic method has been valuable, it is criticized because it is not easily amenable to statistical evaluation. Conventional birth defects epidemiological studies are designed to permit rigorous statistical assessment, but such investigations usually classify congenital anomalies without adequate consideration of their known etiological heterogeneity. It is possible to combine the best aspects of these two approaches to identifying human teratogens in a “dysmorphologic case/control study”. Instead of including all available cases with a given defect, only individuals having the anomaly in the context of a multiple congenital anomaly pattern without a recognizable cause would be selected for inclusion among the case group. The frequency of exposure to the putative teratogen would be determined among these selected cases and among appropriately chosen controls; conventional statistical analysis would then be performed. Although this design reduces the size of the case group compared to a conventional case/control study, the statistical power is unchanged or increased. In addition, biological plausibility is increased by concentrating upon a group of cases that is more likely to have a teratogenic cause.
The role of the visceral yolk sac in hyperglycemia‐induced embryopathies in mouse embryos in vitro
Authors: Hunter E. S. , Sadler T. W. 
Published: June 2005

AbstractThe adverse developmental effects of hyperglycemia to rodent embryos have been shown using whole embryo culture. Although, a mechanism by which hyperglycemia‐induced effects occur is unknown, recent work has focused on the visceral yolk sac as a potential target tissue. Therefore, we have evaluated the developmental effects of hyperglycemia in early head fold stage mouse embryos in vitro and assessed the histiotrophic function of the visceral yolk sac. As has been previously shown in rodents, hyperglycemia produced neural tube closure defects in a concentration dependent manner at 33, 50, and 67 mM glucose using a 44 h exposure period. However, exposure times between 6 and 12 h were sufficient to alter embryonic development when the glucose concentration was 50 or 67 mM. In contrast, early somite stage embryos (4‐6 somite stage) appear to be less sensitive to dysmorphogenesis and a 48 h exposure to 67 mM glucose but not 33 or 50 mM also produced neural tube defects. Hyperglycemia (67 mM) did not alter the uptake of 35S‐methionine and 35S‐cysteine‐labeled hemoglobin (35S‐Hb) in the visceral yolk sac (VYS) in early headfold staged embryos. However, the accumulation of 35S in the embryo was reduced by 16‐18% at glucose concentrations of 50 or 67 mM during the last 12 h of a 44 h exposure period. No effect on VYS uptake or embryonic accumulation of 35S‐labeled products was observed at shorter exposure periods (12‐24 and 24‐36 h). In early somite stage embryos hyperglycemia (⩾ 33 mM) reduced both VYS uptake and embryonic accumulation of 35S‐Hb during the last 12 h of a 48 h exposure period. However, there was no concentration dependent effect on the embryonic accumulation of 35S at the early somite stage. The time course for hyperglycemia‐induced effects on morphology and VYS histiotrophic function are different in the early head fold versus early somite staged embryos. Thus, at the early head fold stage malformations were induced only after a 6‐12 h exposure, while the histiotrophic function was reduced only during the 32‐44 h of exposure. Therefore, our study indicates that hyperglycemia can alter the histiotrophic function of the VYS following long exposure periods. The time course for alterations in VYS histiotrophic function is not correlated with that for induction of malformations but may be related to the growth reduction produced by long‐term exposure to hyperglycemia in vitro.
Maternal methionine supplementation promotes the remediation of axial defects in Axd mouse neural tube mutants
Authors: Essien Francine B. 
Published: June 2005

AbstractThe Axd (axial defects) mouse model system (Essien et al., Teratology 42:183‐194, '90) is characterized by a dominant mutation which causes posterior open neural tube defects (NTD) and a variety of tail anomalies (curly tails, or CT). Repeated backcrosses to BALB/cByJ mice have resulted in a 50% increase in Axd penetrance among neonates of heterozygous matings and loss of a correlation with maternal tail phenotype. Analysis of D12‐D18 embryos from Axd/ + × Axd/ + matings indicates that soft tissues can superficially heal over some lesions from open NTD and that some curly tails can straighten (macroscopically) as gestation proceeds. Similarly, in embryos of Axd/ + × BALB crosses, there is remediation of approximately 33% of the tail flexion defects by birth. Numerous studies show that maternal nutritional status can affect the development of the neural tube and related axial structures. One nutrient of special interest is methionine, which is required for neurulation in cultured rat embryos (Coelho et al., J. Nutr. 119:1716, '89). Thus, the major question addressed by this study was whether supplemental methionine administered to Axd/ + dams crossed to Axd/ + males would alter the prenatal expression of the gene. When given IP (70 mg/kg) on D8 and D9, methionine resulted in a 41% reduction (from 29% to 17%) in the incidence of NTD in D 14 embryos (P <0.01).
Paternal cyclophosphamide treatment causes postimplantation loss via inner cell mass‐specific cell death
Authors: Kelly Sara M. , Robaire Bernard , Hales Barbara F. 
Published: June 2005

AbstractTreatment of the father with the anticancer alkylating agent cyclophosphamide has negative effects on embryonic development in the rat. Four‐week treatment of male rats with a low dose of cyclophosphamide cause a dramatic, dose‐dependent increase in postimplantation death of the progeny. Several recent studies have indicated that the paternal genome is required for the development of the extraembryonic tissues. Thus, the purpose of this study was to determine which tissues of the implanting embryo were affected by paternal exposure to cyclophosphamide. Male Sprague‐Dawley rats were given cyclophosphamide (6 mg/kg/day) or saline by gavage and bred to untreated female rats after 4 weeks of treatment. Pregnant female rats were killed on day 7 of gestation, and implantation sites were dissected from the uterus, fixed, embedded in Epon for semithin serial sectioning, and stained for subsequent light microscopy. Strikingly, many of the implantation sites of affected embryos sired by treated males displayed an apparently normal trophectoderm enclosing a region of dying cells, containing dark‐stained pyknotic nuclei. Very few or no inner cell mass‐derived embryonic cells were present in these implantation sites. Therefore, there is a selective death of inner cell mass‐derived cells in day 7 implantation sites obtained from the progeny of cyclophosphamide‐treated males. The results of this study suggest that treatment of the male with cyclophosphamide can affect paternal genes specifically required for development of the inner cell mass cells of the embryo, without an apparent effect on those genes required for normal trophectoderm.
Axial skeletal malformations induced by acetazolamide in rabbits
Authors: Nakatsuka Toshio , Komatsu Tetsuro , Fujii Takaaki 
Published: June 2005

AbstractIn order to evaluate the teratogenic potential of acetazolamide in rabbits, three groups of 18 artificially inseminated females were treated orally with 50, 100, or 150 mg/kg/day of acetazolamide on days 6‐18 of gestation. These doses induced maternal acidosis and electrolyte changes, consistent with those reported in rats and considered to be a result of carbonic anhydrase inhibition, as well as reductions in maternal body weight gain. At cesarean sections, average fetal body weights in the acetazolamide groups were dosedependently decreased compared with controls. There were no effects of acetazolamide on embryonic survival or external morphology of live fetuses. In the fetal skeletal examination, thoracic and lumbar vertebral malformations occurred in 0.7%, 3.9%, and 6.1% of fetuses in the 50, 100, and 150 mg/kg/day groups, respectively, compared with none in the control group. In addition, missing vertebra was seen in a small number of fetuses in the 100 and 150 mg/kg/day groups. These axial skeletal malformations were, in some cases, associated with costal malformations. These results indicate that acetazolamide at maternotoxic doses can produce axial skeletal malformations in the rabbit. © 1992 Wiley‐Liss, Inc.
Analysis of high dysmorphogenic activity of Ro 13‐6307, a tetramethylated tetralin analog of retinoic acid
Authors: Kochhar D. M. , Penner John D. 
Published: June 2005

AbstractCertain synthetic retinoids differ widely from retinoic acid (RA) in teratogenic potency, being much more or much less effective than RA. It is assumed that the potency of a retinoid may depend on the nature of its interaction with cellular binding components (nuclear retinoic acid receptors or cytoplasmic binding proteins) and, as in the case of retinoids that are mammalian teratogens, on factors that determine its accessibility to the embryo. To investigate some of the factors that contribute to potency, we used a new synthetic retinoid Ro 13‐6307 that differs in structure from RA in having an aromatic ring inserted in its side chain along with gem dimethyl modification of the natural cyclohexenyl ring. Pregnant ICR mice were given a single oral dose (0, 1, or 10 mg/kg) on day 11 of gestation, and the resultant teratogenic outcome was monitored on day 17. Direct effects on cell differentiation were obtained by exposing high density cultures of limb bud mesenchymal cells to a range of concentrations (0.3 ng/ml‐3 μg/ml) of Ro 13‐6307 and scoring for chondrogenic suppression. Concentrations reaching the embryo after maternal administration of Ro 13‐6307 were measured by HPLC to quantify the analog for a period of 4 h after administration of the oral dose. We found that this retinoid was 40‐fold as active as RA in both inducing teratogenesis and suppressing chondrogenesis, yet its concentration in the affected embryo was only a fraction of that achieved after an equivalent dose of RA was employed in a similar protocol. Since the morphogenetic activity of Ro 13‐6307 is disproportionately in excess of its levels in the mouse embryo, obligatory mediation by the receptors or by other binding proteins, or both, is likely involved. © 1992 Wiley‐Liss, Inc.
Trends in rates of multiple vascular disruption defects, Atlanta, 1968–1989: Is there evidence of a cocaine teratogenic epidemic?
Authors: Martin M. Louise , Khoury Muin J. , Cordero José F. , Waters Grady D. 
Published: June 2005

AbstractResearch suggests that, perhaps through mechanisms initiated by vasoconstriction and leading to vessel thrombosis or embolism, cocaine causes vascular disruption defects, and that frequent cocaine use during early pregnancy could disrupt multiple organ systems in the fetus. We hypothesized that if cocaine is an important cause of multiple vascular disruption defects, a rising prevalence of cocaine use by mothers during pregnancy should be accompanied by rising rates of these defects in their offspring. Using data from the Metropolitan Atlanta Congenital Defects Program, we identified all infants born in Atlanta from 1968 through 1989 who had nonsyndromic, provisional vascular disruption defects affecting more than one organ system: 61 infants (78%) had gastrointestinal and genitourinary defects, 7 (9%) had gastrointestinal and abdominal wall defects, 2 (3%) had gastrointestinal and limb reduction defects, 2 (3%) had limb reduction and abdominal wall defects, 2 (3%) had central nervous system and gastrointestinal defects, 2 (3%) had genitourinary and limb reduction defects, 1 (1%) had genitourinary and abdominal wall defects, and 1 (1%) had central nervous system and genitourinary defects. The prevalence of Atlanta infants with more than one vascular disruption defect is 0.13 per 1,000 live births. Chi‐square analysis for trends showed no increase in prevalence during the study period. Our data are from one of the first population‐based studies in which trends for defects potentially caused by maternal cocaine use are examined; the results of our study show no significant change in the prevalence of multiple vascular disruption defects over time. We suspect that if cocaine is a teratogen, its teratogenicity is weak or is associated with a small subset of birth defects that are yet to be identified. © 1992 Wiley‐Liss, Inc.