Neuropsin promotes oligodendrocyte death, demyelination and axonal degeneration after spinal cord injury

Previous studies indicated that the expression of neuropsin, a serine protease, is induced in mature oligodendrocytes after injury to the CNS. The pathophysiology of spinal cord injury (SCI) involves primary and secondary mechanisms, the latter contributing further to permanent losses of function. To explore the role of neuropsin after SCI, histochemical and behavioral analyses were performed in wild-type (WT) and neuropsin-deficient (neuropsin(-/-)) mice using a crush injury model, a well-characterized and consistently reproducible model of SCI. In situ hybridization revealed that neuropsin mRNA expression was induced in the spinal cord white matter from WT mice after crush SCI, peaking at day 4. Neuropsin(-/-) mice showed attenuated demyelination, oligodendrocyte death, and axonal damage after SCI. Although axonal degeneration in the corticospinal tract was obvious caudal to the lesion site in both strains of mice after SCI, the number of surviving nerve fibers caudal to the lesion was significantly larger in neuropsin(-/-) mice than WT mice. Behavioral analysis revealed that the recovery at days 10-42 was significantly improved in neuropsin(-/-) mice compared with WT mice in spite of the severe initial hindlimb impairments due to SCI in both strains. These observations suggest that neuropsin is involved in the secondary phase of the pathogenesis of SCI mediated by demyelination, oligodendrocyte death, and axonal degeneration.

The venocutaneous fistula: a new technique for reducing venous congestion in replanted fingertips

The venocutaneous fistula technique, which involves the construction of a temporary venous return bypass using a venous graft, was devised to prevent venous congestion after fingertip replantation surgery. The proximal side of the venous graft is anastomosed to a vein at the dorsum of the finger. The distal side of the graft is sutured to the skin around a punch wound on the volar side of the replanted fingertip. This procedure was applied successfully to four fingertips in two patients without any anastomosis of the proper vein or the application of bleeding wound techniques or medicinal leeches. This method provides an excellent alternative in the treatment of venous congestion.