Remyelination of demyelinated rat axons by transplanted mouse oligodendrocytes.

The injection of the gliotoxic agent ethidium bromide (EB) into spinal white matter produces a CNS lesion in which it is possible to investigate the ability of transplanted glial cells to reconstruct a glial environment around demyelinated axons. This study demonstrates that transplanted mouse glial cells can repopulate EB lesions in rats provided tissue rejection is controlled. In X-irradiated EB lesions in cyclosporin-A-treated rats, mouse oligodendrocytes remyelinated rat axons and, together with mouse astrocytes, re-established a CNS environment. When transplanted into nonirradiated EB lesions in nude rats, mouse glial cells modulated the normal host repair by Schwann cells to remyelination by oligodendrocytes. In both X-irradiated and non-irradiated EB lesions, transplanted mouse glial cells behaved similarly to isogenic rat glial cell transplants (Blakemore and Crang Dev Neurosci, 1988;10:1-10; J Neurocytol, 1989;18:519-528). These findings indicate that the cell-cell interactions involved in reconstruction of a glial environment are common to both mouse and rat.     

Unsatisfactory hepatic perfusion after placement of an implanted pump and catheter system: angiographic correlation

Thirty-five patients with scintigrams showing unsatisfactory hepatic artery perfusion after surgical placement of an implanted pump and catheter system were examined with selective angiography (33 cases) or digital subtraction angiography (DSA) during which the contrast material was injected through the side port of the pump (six cases). In 34 of 35 cases, the cause of the unsatisfactory (either extrahepatic or incomplete) hepatic perfusion was defined. DSA was definitive in only two cases, in which extrahepatic flow through collateral vessels was demonstrated. The cause of the perfusion defect was hepatic artery thrombosis in 14 cases, extrahepatic flow through collateral vessels in 14 cases, a misplaced catheter in four cases, and a short proper hepatic artery without adequate length for mixing in two cases. Although hepatic artery perfusion scintigraphy is the primary tool for evaluation of hepatic perfusion after catheter placement, angiography plays an important role in treating the subset of patients with unsatisfactory hepatic perfusion.     

Lethal fetal anomalies: sonographic demonstration

Sonographic demonstration of a lethal fetal anomaly may dramatically alter obstetrical management. For example, cesarean section for fetal distress may not be performed if it is known that the fetus will not survive outside the uterus. The author describes the common fetal anomalies that are predictably fatal.     

Association of heterotopic gray matter with seizures: MR imaging. Work in progress

Heterotopic gray matter, which previously had been associated with severe congenital malformations of the brain and developmental delay, was found without these associated conditions. The authors found ten cases of heterotopic gray matter on magnetic resonance (MR) images. The lesions had a signal intensity that was isointense compared with that of gray matter on T1, spin-density, and T2-weighted images. Nine of the ten cases were associated with a seizure disorder. The tenth case, discovered during a workup for metastatic lung disease, was confirmed with pathologic studies. Heterotopic gray matter is the presence of cortical neurons in an abnormal location, which may be periventricular (nodular) or within the white matter (laminar). A knowledge of heterotopic gray matter and its association with seizures may prevent the misinterpretation of findings on MR images.