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SYNOPSIS Histopathological findings of biopsied peripheral nerve and muscle were studied in a case with myxoedematous polyneuropathy. The most striking findings in the sural nerve were segmental demyelination and onion bulb formation with scanty mucinous deposits in addition to marked loss of large myelinated nerve fibres. The peroneus brevis muscle revealed the association of neuropathic and myopathic changes. It is suggested that myxoedematous polyneuropathy might be intrinsic neuropathy due to metabolic disorder of Schwann cells related to hypothyroidism, resulting in segmental demyelination, not merely compressive neuropathy due to mucinous deposits in the peripheral nerves.

Epstein-Barr (EB) virus-associated primary smooth muscle tumors have been reported in immunosuppressed young patients with acquired immunodeficiency syndrome (AIDS) and young people who have undergone liver transplantation. An autopsy case of EB virus-associated smooth muscle cell tumor in a 21 year old female who received immunosuppressive therapy following renal transplantation is reported. Multiple tumor nodules were present in the liver, but no primary lesion was found in any other organ. Histologically, the nodules were composed of spindle cells, positive for alpha-smooth muscle actin, which were arranged in fascicles and closely associated with vascular channels, thereby suggesting a vascular smooth muscle cell origin. EB virus infection of the tumor cells was clearly demonstrated by in situ hybridization with an EB virus-encoded RNA 1 (EBER-1) probe. The present case illustrates that EB virus infection may play some role in the development of smooth muscle tumors not only in immunocompromised young patients with liver allografts, but also in those with renal allografts.

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We have previously demonstrated that interleukin 3 (IL-3) has a neurotrophic effect on central cholinergic neurons and have demonstrated the presence of IL-3 receptor (IL-3R)beta subunits in septal cholinergic neurons by reverse-transcribed polymerase chain reaction (RT-PCR) and immunohistochemistry. In order to confirm that the expressed IL-3R is functional, we conducted experiments to show an alpha subunit of IL-3R. The alpha subunit was clearly demonstrated by RT-PCR in the central cholinergic neuronal hybrid cell line SN6, but not in its mother cell line N18TG2, and the expression was slightly upregulated after IL-3 treatment. Choline acetyltransferase and vesicular acetylcholine transporter mRNAs were significantly increased in SN6 after treatment with IL-3. Immunohistochemically, IL-3R alpha-positive cells were mainly present in the medial septal and basal forebrain region, and the stained cells were similar to choline acetyltransferase-positive cells in shape and distribution. The IL-3R alpha-positive cells slightly increased two days after fimbria-fornix transection and decreased seven days after. These findings suggest that functional IL-3 receptors are expressed in the central cholinergic neurons and contribute to some physiological roles such as the differentiation and maintenance of these neurons.