The release rate of insulin, as a model peptide, from gelatin microspheres (GM) prepared with gelatin having various cross-linking densities in vitro was examined. The release of insulin from GM showed the burst effect, followed by a slow release phase regardless of the cross-linking density of gelatin. The total amount of insulin released in 2 weeks decreased with increasing cross-linking density of gelatin. The release rate of insulin within 6 h was well correlated with the cross-linking density of gelatin. The remaining amounts of both insulin and GM after injection of insulin incorporated in GM to mice femoral muscle tissue were also examined in vivo. Both insulin and GM rapidly disappeared from the injection site within 1 day, and thereafter slowly disappeared over 14 days. The time courses of the remaining amounts were fairly similar to each other. Furthermore, the remaining amount of insulin 1 day after administration was well correlated with the cross-linking density of gelatin. These data suggest that insulin was released from GM with the degradation of GM in mice muscular tissue and that the release rate of insulin can be controlled by modifying the cross-linking density of gelatin. In conclusion, the control of the release rate of insulin from GM can be achieved under both in vitro and in vivo conditions by gelatin through the alteration of cross-linking conditions.

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PubMedDate not supplied

Amyotrophic lateral sclerosis: occurrence of Bunina bodies in the locus ceruleus pigmented neurons.

Bunina bodies, which are small eosinophilic intracytoplasmic inclusions, have been considered to be specific for amyotrophic lateral sclerosis (ALS), a fatal neurodegenerative disease of unknown cause in adults. They are found usually in the remaining lower motor neurons. We encountered a 66-year-old woman with sporadic ALS showing Bunina body-like eosinophilic inclusions in the cytoplasm of some pigmented neurons in the otherwise intact locus ceruleus (LC). Ultrastructural examination of the LC confirmed that a few pigmented neurons actually contained inclusions identical to Bunina bodies. The finding indicates that Bunina bodies can occur in LC pigmented neurons and suggests that LC may also be involved in the disease process in ALS.

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