Concentric sclerosis (Baló): Morphometric and in situ hybridization study of lesions in six patients

Brain tissues from 6 patients with concentric sclerosis (Baló) were examined by in situ hybridization, immunocytochemistry, morphometry, and histological methods. The patients were 24 to 48 years old and had progressive cerebral symptoms and signs that lasted 15 to 100 days. Large demyelinative lesions, most frequent in the frontal white matter, contained alternating bands of demyelinated and partly myelinated white matter that were arranged in concentric or mosaic patterns. In the areas of demyelination, axons were relatively well preserved and there were perivascular inflammatory infiltrates. In 2 specimens, lesions contained regions with the characteristic appearance of actively demyelinating multiple sclerosis plaques. Oligodendroglial densities were highest in normal-appearing white matter, lower in partially myelinated areas, and lowest in demyelinated areas, which also contained many hypertrophic astrocytes closely associated with oligodendroglia. Messenger RNA levels for myelin-related proteins followed the same pattern; they were lowest in demyelinated areas, higher in partially myelinated areas, and highest in normal-appearing white matter beyond lesion margins. Our findings suggest that concentric sclerosis is a variant of multiple sclerosis, that oligodendroglial loss is important in the pathogenesis of demyelination, and that partially myelinated areas probably represent stages of ongoing myelin breakdown rather than remyelination of previously demyelinated areas.     

Regulation of interleukin 6 expression in murine bone marrow stromal cells.

The regulation of interleukin 6 (IL-6) expression in the B-lymphocyte-supporting murine stromal cell line BMS2 has been examined in response to exogenous cytokines and chemical agents. Kinetic analyses of IL-6 mRNA induction and decay are presented together with analysis of the IL-6 biological activity. The cytokines tumor necrosis factor, interleukin 1 (alpha and beta), and transforming growth factor beta, as well as forskolin and dibutyryl cyclic AMP, all induce a transient rise in the steady-state level of IL-6 mRNA and an increased release of IL-6 protein. To study its regulation at the chromatin level, the murine IL-6 genomic gene has been cloned. Induction of IL-6 expression correlates with increased DNA nicking, consistent with increased topoisomerase I and endogenous nuclease activity. This finding is supported by kinetic analyses using camptothecin, a topoisomerase I inhibitor. We conclude that IL-6 regulation in murine stromal cells capable of supporting B-lymphopoiesis is comparable to that observed in human diploid fibroblasts.     

Non–rabies Lyssavirus human encephalitis from fruit bats: Australian bat Lyssavirus (pteropid Lyssavirus) infection

A 39-year-old woman died of encephalitis a few weeks after being scratched by fruit bats. Autopsy disclosed meningoencephalomyelitis, and revealed neuronal intracytoplasmic inclusions which had similarities to Negri bodies of rabies. Laboratory investigations detected a Lyssavirus type previously identified only in fruit bats. This appears to be the first human case of encephalitis due to this Lyssavirus type.