Hamster pancreatic islets were encapsulated by a biocompatible membrane composed of the molecular sequence of alginate-polylysine-alginate. The encapsulated islets released insulin into the culture medium in response to secretagogues in short-term incubation. In long-term culture, the encapsulated islets maintained their insulin-releasing capacity for 28 days at a level similar to that of the unencapsulated islets. No overgrowth of fibroblastic cells was observed inside the capsule even after 70 days of culture. Further, the encapsulated hamster islets were xenotransplanted to streptozotocin-induced diabetic rats intraperitoneally. Some of the encapsulated islets, which were recovered from a recipient 27 days after transplantation, were found to be viable, although prolonged normalization of fasting plasma glucose levels of the recipients could not been achieved. On the contrary, the unencapsulated islets were replaced by massive connective tissue elements and insulin-positive B cells were hardly detected within the grafts 22 days after transplantation. The results of this study seem to confirm the potential of the application of the encapsulating technique to primary culture of parenchymal cells and to transplantation of pancreatic islets.

Alginates↗

PubMedDate not supplied

A case of localized solitary microscopic honeycombing in the lung: an unusual appearance on CT.

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Bronchi↗

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Regional differences of serotonin-mediated synaptic plasticity in the chicken spinal cord with development and aging.

Previous studies in our laboratory [3,17] have demonstrated that serotonin (5-HT) appears to have a trophic-like effect in enhancing synapse formation and maintenance in both the developing and the adult central nervous system. In the present study, we focused on age-related changes in the density of the axosomatic and axodendritic synapses and the number of 5-HT-positive fibers in the chicken spinal cord, with special reference to differences between the ventral (laminae VII and IX) and the dorsal (lamina I) horn. At 1 week posthatching (P1W), a transient overproduction of synapses and 5-HT-immunoreactive fibers occurred in lamina IX; all parameters had returned to their initial levels by 1 month post-hatching (P1M). The density of synapses further decreased by about 40% between P6M and P2Y (2 years posthatching). Although the magnitude of the transient increase in lamina VII was less than that in lamina IX, the changing pattern of the synapses and the 5-HT-positive fibers was similar in both regions. In the ventral horn, thin 5-HT-positive fibers were most prominent at P1W and then decreased with development; thin 5-HT-positive fibers were still found at P6M but had almost disappeared by P2Y. By contrast, at P2Y the density of the synapses and the 5-HT-positive fibers in the dorsal horn was even higher than that of younger animals. Reduction of 5-HT levels in P2Y-old chickens by p-chlorophenylalanine (pCPA) administration decreased the synaptic density in lamina I but not in lamina IX. The results of this study demonstrate that 5-HT-mediated synaptic plasticity is markedly different in the ventral and dorsal horns of the aged chicken. In the ventral horn, synaptic plasticity reached a maximum at about P1W, remained stable in the young-adult period, and then finally disappeared in the aged chicken. Conversely, the results suggest that in the dorsal horn, 5-HT fibers continue to mediate the trophic influence on synaptic plasticity even in the old chicken.

Aging↗