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Biomedical subjects

S Geuna

Publications and source records attributed to S Geuna.

45 records · Page 3Linked to original sources
PubMed1992

[Satellite cells of te dorsal root ganglia in neuronal hypertrophy].

Amputation of the lizard tail is followed by its complete regeneration over a period of six-eight months. The new tail is innervated only by the last three pairs of spinal nerves upstream from the plane of amputation, since no nerve cells are present in the regenerated. The corresponding dorsal root ganglia increase in volume (hypertrophic ganglia) and most of their sensory neurons become hypertrophic. Satellite cells belonging to this hypertrophic ganglia increase in number. This paper describes an autoradiographic study, after administration of tritiated thymidine, of the hypertrophic dorsal root ganglia of the lizard during tail regeneration. We evaluated the number of satellite cells which neo-synthetize DNA ("labeling index = LI%) and are therefore suitable to undergo cell division. The LI% was significatively increased in hypertrophic ganglia when compared to internal control ganglia (not directly involved in the reinnervation process) and normal ganglia (lizards with intact tails). The comparison between internal control ganglia and normal ganglia showed higher LI% values in the formers, although this difference was not statistically significative. These results are in line with those obtained by other authors and suggest that satellite cells of dorsal root ganglia can undergo cellular proliferation also in the adult, especially in particular experimental conditions.

Animals↗
PubMed1992

[Hyperplasia of the intestinal smooth muscle tissue proximal to a partial surgical stenosis: an autoradiographic study].

Hypertrophy of the smooth muscle wall of the rat small intestine occurs in the loops upstream from a partial surgical stenosis. This phenomenon is due both to cell hypertrophy and cell proliferation (hyperplasia). The thickness of the muscular layers reached its maximum after ten days from the intervention and then was maintained over the following days. Hyperplasia of the smooth muscle tissue has been demonstrated by means of autoradiography after administration of tritiated-thymidine. This investigation revealed the presence of 37%-44.5% of heavily labeled smooth muscle nuclei, index of active DNA neo-synthesis. On the contrary, no labeled nuclei were observed in the downstream tract as well as in the small intestine of the controls. These results, together with those obtained by other researchers, confirms that the smooth muscle tissue can undergo cell proliferation under particular conditions and that this phenomenon is often associated with the hypertrophic process.

Animals↗
PubMed1991

Electrophoretic analysis of neuronal genomic DNA from hypertrophic spinal ganglia during lizard tail regeneration.

Cytoplasmic and nuclear hypertrophy in neurons from the last 3 pairs of sensory ganglia left in situ cranially to the plane of amputation occurs during lizard tail regeneration. Cytophotometry after Feulgen staining demonstrated the presence of some neurons, from hypertrophic ganglia, whose quantity of DNA exceeded the diploid level (hyperdiploid neurons). In the present work agarose gel electrophoresis of total genomic DNA extracted from hypertrophic ganglia showed one or two bands migrating below the high molecular weight DNA, pointing to a selective amplification of discrete DNA segments.

Amputation, Surgical↗
PubMed1988

DNA content in neurons of Auerbach's plexus under experimental conditions in adult rats.

Some nerve cells of the Auerbach's myenteric plexus of the intestine of the adult rat, which hypertrophied following a surgically induced stenosis, began DNA synthesis unrelated to mitotic division. The cytophotometric analysis confirmed and quantified the amount of synthesis revealed by autoradiography with tritiated thymidine uptake. Numerous nerve cells show a DNA content exceeding the diploid level. Only a few of these show twice the diploid content. The significance of the DNA synthesis is discussed.

Animals↗
PubMedDate not supplied

A stereological study of long-term regeneration of rat severed sciatic nerve repaired by means of muscle-vein-combined grafts.

This study is a stereological analysis, by the 2-D dissector method, on the long-term regeneration of myelinated nerve fibers of the rat sciatic nerve repaired by muscle-vein-combined graft, a surgical technique that has been shown to be a valid tool for the repair of peripheral nerve defects with substance loss. Quantitative analysis showed that the total number and mean density of regenerated myelinated nerve fibers was significantly higher than in control nerves. The contrary was true for fiber mean size. The morpho-quantitative parameters of regenerated fibers from nerves repaired by the muscle-vein-combined graft were similar to those observed in rats where nerve defects were repaired by direct nerve suture thus confirming the validity of this surgical technique.

Animals↗