Members of the workgroup on birth defects and developmental disorders discussed methods to assess structural anomalies, genetic changes and mutations, fetal and infant mortality, functional deficits, and impaired fetal and neonatal growth. Tier 1 assessments for all five adverse reproductive outcomes consist of questionnaires and reviews of medical records rather than laboratory testing of biologic specimens. The work-group members noted a role for neurodevelopmental testing and for limited genetic studies, such as karyotyping in Tier 2 assessments. Emerging methodologies to identify chromosomal aberrations, DNA adducts, and repair inhibition were reserved for Tier 3.

Adult↗

PubMedDate not supplied

The teratogenicity of N(omega)-nitro-L-ariginine methyl ester (L-NAME), a nitric oxide synthase inhibitor, in rats.

Exposure of gravid rats to the nitric oxide synthase inhibitor N(omega)-nitro-L-arginine methyl ester (L-NAME) in drinking water or by implanted osmotic minipumps significantly elevates maternal blood pressure, reducing uteroplacental perfusion. Administration by either route causes fetal growth retardation, but oral exposure also causes hind limb reduction malformations. The present study employed both oral and intraperitoneal routes to determine the period of sensitivity to developmental toxicity, dose-response, and possible fetotoxic mechanisms. Hind limb hemorrhage occurred only in litters from dams exposed to oral doses of 1 to 2 mg/mL from gestational days 15 through 17. In contrast to oral exposure, single intraperitoneal injections caused both fore and hind limb reductions at doses of 25 mg/kg and above administered on gestational day 16 and later. Many other exposures that reduce uteroplacental perfusion have been associated with vascular disruptive dysmorphogenesis. These exposures include phenytoin, calcium channel inhibitors, cocaine, and uterine vascular clamping. Limb hemorrhage induced by these exposures is usually limited to distal structures, typically phalanges, and the incidence of affected fetuses rarely exceeds 50%. By contrast, hemorrhage caused by L-NAME frequently involves entire limbs, extending into adjacent flank in severe instances, and 100% of fetuses from treated dams may be affected. The basis of this difference and the differing defect patterns associated with the various routes of exposure are unclear, but the generation of reactive oxygen species during resumption of normal perfusion may play a role in this vascular disruption.

Abnormalities, Drug-Induced↗

PubMedDate not supplied

Intestinal ganglioneuroblastoma in a 22-week fetus.

The clinical history and autopsy findings of a 22-week fetus with intestinal ganglioneuroblastoma, cardiac anomalies, omphalocele, and ileal atresia are presented. Ganglioneuroblastoma was confined to the large intestine and was not suspected prenatally despite ultrasonographic examination. Although enteric ganglia share neural crest lineage with other sites of congenital neuroblastoma, this is the first report of a primary intestinal ganglioneuroblastoma in a fetus or child. Various hypotheses are discussed to explain the coexistence of cardiac malformation and congenital neuroblastoma in this fetus and other cases in the literature. It is hypothesized that other malformations evident in this fetus were caused by the tumor, possibly as teratogenic effects of neuroblastoma-derived catecholamines during embryogenesis.

Abnormalities, Multiple↗