Hemoglobin Gower 1, the structure of which is thought to be epsilon(4), is the predominant hemoglobin in early human embryonic life. This finding suggests that the production of (epsilon)-chains initially exceeds that of other known (alpha, beta, gamma, and delta) chains.

Electrophoresis↗

PubMedDate not supplied

Hemangioblastoma of the conus medullaris associated with cutaneous hemangioma.

A 6-month-old infant is reported with a spinal cord hemangioblastoma located in the conus medullaris associated with an overlying congenital dermal sinus and cutaneous capillary hemangioma. There were no neurologic deficits either preoperatively or following removal of the tumor. The skin and spinal cord lesions were believed to represent an isolated vascular malformation. This spinal cord hemangioblastoma is unusual because of the age of the patient, manner of clinical presentation, location in the caudal spinal cord, and pathologic characteristics. We review the literature and discuss the associations of spinal cord hemangioblastomas with cutaneous and other lesions.

Female↗

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

Pathophysiology of isolated lateral ventriculomegaly in shunted myelodysplastic children.

Eight myelodysplastic children developed isolated lateral ventriculomegaly following shunt insertion for progressive hydrocephalus after closure of a myelomeningocele. In all patients a low-pressure distal slit valve (Uni-shunt) system preceded development of an isolated contralateral ventricle. Six of 8 children required a second contralateral shunt for a symptomatic isolated ventricle. Magnetic resonance imaging demonstrated a collapsed ventricle ipsilateral to the shunt secondary to distortion of the foramen of Monro. This was clearly depicted using three-dimensional color reconstructions of the ventricular anatomy. Low-pressure distal slit valves should be avoided in myelodysplastic children to prevent postshunt ventricle isolation.

Cerebral Ventricles↗

PubMedDate not supplied

Neural tube defects.

Neural tube defects (NTDs) are a group of malformations of the brain and spinal cord that originate at various times during gestation. The most common NTDs are anencephaly and meningomyelocele, which arise during the process of neurulation, a well-defined period between the 17th and 30th day after ovulation. These NTDs are clinically apparent by being open, ie, leaving nervous tissue exposed, in contrast to postneurulation NTDs that are skin covered. The incidence of NTDs is declining in several areas of the world, including the United States. While the reasons for this are unclear, there seems to be some effect from prenatal diagnosis, genetic counseling, and possibly nutritional supplementation.

Gestational Age↗