Inhibition of proliferation and expression of T-antigen in SV40 large T-antigen gene-induced immortalized cells following transplantations.

Rat dopamine-producing nerve cells (1RB3AN27) and rat parotid acinar cells (2RSG) were immortalized by insertion of simian virus 40 (SV40) large T-antigen gene (LTa). Both of these cells divided and produced nuclear LTa in vitro. In order to assess the relationship between cell proliferation and expression of LTa in vivo, immortalized dopamine-producing nerve cells and parotid cells were grafted into the striatum and parotid gland of adult Sprague-Dawley rats, respectively. Grafted cells exhibited nuclear LTa at 1 day but not at 7 and 30 days after transplantation. At 30 days after transplantation, no tumor was found, and there was no evidence of cell division as determined by H and E staining. When the striatal areas containing the grafts were cultured, these cells did not express LTa at 4 days after plating; however, after 3 weeks, when most host cells were eliminated, the cultured grafted cells expressed LTa. After 3 months of culturing, only cells exhibiting LTa were present. These cells had the same morphology and divided with the same doubling time as 1RB3AN27 cells before grafting. Results suggest the presence of a LTa-inhibiting factor in vivo, and support the hypothesis that the expression of LTa is directly linked with proliferation of immortalized cells.

Transplantation of immortalized, nontumorigenic parotid acinar cells into the allogeneic rat parotid gland and oral submucosa.

The recent establishment of an immortalized clonal cell line of rat parotid acinar cells (2RSG) by transfecting isoproterenol-stimulated parotid cells with a plasmid vector, pSV3neo which carries the large T-antigen gene from SV40 virus, afforded the opportunity to develop a model for parotid acinar cell transplantation. Single cell suspensions of 2RSG cells labeled with a fluorescent tracer, DiI, were injected into the parotid gland or oral submucosa of allogeneic adult rats. The grafted cells survived and were functionally viable for at least 30 days. Histological sections revealed no evidence of infiltration of leukocytes or lymphocytes. Grafted cells did not form tumors. Results suggest that allogeneic parotid acinar cell transplantation is a feasible technique in the animal model.

High-resolution computed tomography of the temporal bone of the Macaca mulatta monkey.

High-resolution computed tomography (CT) slices of the temporal bone of the Macaca mulatta monkey were performed and key anatomical landmarks were identified and labelled. The scans provided detailed anatomical definition of the monkey temporal bone and were considered a useful basis for studying the anatomy of a primate model.