Enrollment of extremely low birth weight infants in a clinical research study may not be representative.

BACKGROUND AND OBJECTIVE: The Surfactant Positive Airway Pressure and Pulse Oximetry Randomized Trial (SUPPORT) antenatal consent study demonstrated that mothers of infants enrolled in the SUPPORT trial had significantly different demographics and exposure to antenatal steroids compared with mothers of eligible, but not enrolled infants. The objective of this analysis was to compare the outcomes of bronchopulmonary dysplasia, severe retinopathy of prematurity, severe intraventricular hemorrhage or periventricular leukomalacia (IVH/PVL), death, and death/severe IVH/PVL for infants enrolled in SUPPORT in comparison with eligible, but not enrolled infants. METHODS: Perinatal characteristics and neonatal outcomes were compared for enrolled and eligible but not enrolled infants in bivariate analyses. Models were created to test the effect of enrollment in SUPPORT on outcomes, controlling for perinatal characteristics. RESULTS: There were 1316 infants enrolled in SUPPORT; 3053 infants were eligible, but not enrolled. In unadjusted analyses, enrolled infants had significantly lower rates of death before discharge, severe IVH/PVL, death/severe IVH/PVL (all < 0.001), and bronchopulmonary dysplasia (P = .003) in comparison with eligible, but not enrolled infants. The rate of severe retinopathy of prematurity was not significantly different. After adjustment for perinatal factors, enrollment in the trial was not a significant predictor of any of the tested clinical outcomes. CONCLUSIONS: The results of this analysis demonstrate significant outcome differences between enrolled and eligible but not enrolled infants in a trial using antenatal consent, which were likely due to enrollment bias resulting from the antenatal consent process. Additional research and regulatory review need to be conducted to ensure that large moderate-risk trials that require antenatal consent can be conducted in such a way as to ensure the generalizability of results.

L-cysteine, N-acetyl-L-cysteine, and glutathione protect Xenopus laevis embryos against acrylamide-induced malformations and mortality in the frog embryo teratogenesis assay.

Dietary acrylamide is largely derived from heat-induced reactions between the amino group of the free amino acid asparagine and carbonyl groups of glucose and fructose during heat processing (baking, frying) of plant-derived foods such as potato fries and cereals. After consumption, acrylamide is absorbed into the circulation and is then distributed to various organs, where it can react with DNA, neurons, hemoglobin, and essential enzymes. In the present study, we explored the potential of L-cysteine (CySH), N-acetyl-L-cysteine (NAC), reduced glutathione (GSH), and the amino acid glycine (Gly) to protect frog embryos against acrylamide-induced developmental toxicity in the frog embryo teratogenesis assay - Xenopus (FETAX). To test the antiteratogenic potential, based on concentration-response study ranging from 0.07 to 4.22 mM acrylamide in FETAX solution (pH 8.1), we selected concentrations of acrylamide that induced 100% malformations and mortality. At the end of 96 h, we counted survivors and malformed embryos and measured embryo length. The data show that CySH, NAC, and GSH protected the embryos against acrylamide induced malformations and mortality to different degrees. CySH and GSH protected the embryos against both malformations and mortality, whereas NAC protected only against mortality. Gly had no protective effect. Possible mechanisms of the protective effects and the dietary significance of the results of this and related studies for food safety and human health are discussed.

Developmental effects of ethinylestradiol on reproductive organs of female mice.

Reproductive organs in female mice are susceptible to exposure to estrogenic substances especially during development. In the present study, C57BL/6J female mice were exposed to the synthetic estrogens ethinylestradiol (EE2) or diethylstilbestrol (DES), 10-100 or 6.7-67 microg/kg bw, respectively, in utero from day 10 to 18 of pregnancy, and their effects were analyzed at 30 and 40 days of age. Both EE2 and DES reduced the survival rate of fetuses and newborns in a dose-dependent manner. Polyovular follicles (PF) were found in the ovaries of all groups at 30 days of age including oil-injected controls. However, the incidence of PF was significantly higher in the 50 microg/kg EE2- and 33.3 microg/kg DES-exposed mice than the control. In vaginal epithelia of the in utero EE2 exposed, ovariectomized mice, stratification and cornification were encountered even 10 days after ovariectomy. Especially, vaginae in the ovariectomized mice given high dose of EE2 or DES in utero showed ovary-independent proliferation of the epithelium. Thus, it is clear that prenatal exposure to EE2 or DES induces reproductive abnormalities, including PF, ovary-independent vaginal epithelial stratification and cornification.

Assessing the predictive validity of frog embryo teratogenesis assay-Xenopus (FETAX).

The ability of frog embryo teratogenesis assay - Xenopus (FETAX) to identify the potential developmental toxicity of a group of diverse chemicals was evaluated by comparison with results from in vivo studies in rats. A total of 12 chemicals, three of which were shown to be teratogenic in vivo, four of which were embryolethal (but not teratogenic) in vivo, and five which did not produce any developmental toxicity in vivo in the rat were evaluated using FETAX. Results of the FETAX test with these 12 blind-coded compounds correctly predicted that three chemicals had strong teratogenic potential, four had low teratogenic hazard potential but were embryolethal, and five posed little if any developmental toxicity hazard. In addition, this study concluded that within a family of chemistry analogs could be ranked according to relative teratogenic hazard and that for the teratogenic compounds the types of malformations induced in Xenopus mimicked the abnormalities induced in vivo in rats. In summary, these results confirmed that the FETAX assay is predictive and can be useful in an integrated biological hazard assessment for the preliminary screening of chemicals. Teratogenesis Carcinog. Mutagen. 20:87-98, 2000.

An avian model for comparative studies of insulin teratogenicity.

This study was designed to explore the effects of purified insulin during early stages of chick embryo development, and to search for variations between different molecular structures of the hormone. Chicken embryos were treated in ovo with a single dose of insulin (porcine or bovine), in only one stage of development between day 0 and day 9. Two susceptible periods were found. The earliest period (day 0 to day 3), characterized by abnormalities in the caudal vertebrae and a high mortality rate, was followed by a period with a different set of malformations, a syndrome classified as achondroplasia. The rate of achondroplastic embryos was significantly higher with porcine rather than with bovine insulin. Paradoxically, insulin at physiological doses has stimulatory effects in growth and development but, in contrast, has inhibitory effects at higher doses. The precise signalling cascade of events in the target cells is still unclear. The possible interpretations of our results are discussed. The similarity between the insulin-induced abnormalities in the chicken embryos and the caudal regression syndrome, the most common malformation found in infants of diabetic women, suggests a common mechanism. This circumstance offers the chicken embryos as an excellent in vivo model for research on the mechanism of action of insulin during normal and abnormal development.

Effects of diethylene glycol monomethyl ether on pregnancy and postnatal development in rats.

The effects of oral treatment of Wistar rats with diethylene glycol monomethyl ether (diEGME) were examined. In a preliminary dose-finding study with non-pregnant rats, diEGME treatment at doses up to 4,000 mg/kg/day on 11 consecutive days decreased relative weights of thymus and pituitary gland, white and red blood cell counts, hemoglobin concentrations and hematocrit levels. In pregnant rats, treatment at doses of > 3,000 mg/kg/day (over gestation days 7-17) caused total resorption of all litters. In teratology and postnatal studies, pregnant rats were treated with diEGME at doses of 0, 200, 600, and 1,800 mg/kg/day from day 7 through 17 of gestation. At 200 mg/kg, there were no adverse effects on either dams, fetuses, or neonates. At 600 mg/kg, dams were not affected, but fetal body weights were decreased, and fetal thymus and ossification were adversely affected. At 1,800 mg/kg, maternal thymus weights and food consumption were decreased, and visceral malformations of the cardiovascular system were seen in 28.0% of the fetuses. Only 6.3% of the pups delivered by dams treated with 1,800 mg/kg of diEGME survived for 4 days after birth. Thus, diEGME was teratogenic in Wistar rats, but the spectrum differed from that in Sprague-Dawley rats. In addition to teratogenicity, diEGME had significant adverse effects on postnatal development. The most sensitive organ to diEGME was the thymus in both dams and fetuses.

Congenital malformations, mortality and styrene exposure.

The prevalence of congenital malformations among children born to styrene-exposed male and female workers, as well as the mortality of the exposed workers, was studied. A cohort of 2,209 workers (1,698 men, 511 women) was selected from the personnel files of 160 workplaces using styrene in the manufacture of reinforced plastic products. The earliest exposure histories began in 1960, but the majority of workers had been exposed after 1967. The data on children born to the exposed workers were linked with those of the Register of Congenital Malformations. The number of malformations of children born to the workers was, both before and during the styrene exposure, below the expected values. In the cohort there were 37 observed deaths (expected 74.0), six of which were due to cancer (expected 13.0). The cancer sites were the stomach (2 cases), bronchus (1), breast (1), ovary (1), and kidney (1 case). There were no cases of lymphatic or haematopoietic cancer. Most of the cancers appeared after short exposure times and soon after the commencement of exposure.

Birth defects and household water supply. Epidemiological studies in the Mount Gambier region of South Australia.

We report a descriptive study indicating a localised excess of congenital malformations in Mount Gambier, South Australia, and summary results of a subsequent case-control study showing an association between the occurrence of congenital malformations and the consumption of underground water by pregnant women. The internal cohesion of the data analyses, and the plausibility conferred by experimental evidence, suggests that the underground water, and its elevated concentration of nitrates, may warrant further consideration as a source of human teratogens.