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Diabetes was induced in Lewis rats with streptozotocin. Six to nine months later glomeruli showed significant mesangial matrix thickening; by immunofluorescent microscopy large quantities of IgG, (i\C and in some instances, IgM were seen in a mesangial distribution. Sustained normoglycemia was then achieved in nine of these animals by successful pancreatic islet isotransplantation. Three months following transplantation five of these animals had decreased mesangial matrix while four had no further progression of glomerular lesions. All had a marked decrease in IgG, IgM and |3 iC in the mesangium. In contrast, untreated diabetic rats, over the same time period, demonstrated progressive mesangial thickening and focal tuft sclerosis. Immunoglobulins and complement were in the mesangium in quantities equal to or greater than seen in earlier biopsies. Thus, successful pancreatic islet transplantation in the rat results in regression or arrest of the diabetic glomerular lesion. DIABETES 23:748-53, September, 1974.Rats with chronic experimentally induced diabetes mellitus develop progressive glomerulosclerosis, 1 " 4 which is associated with the deposition of large quantities of immunoglobulin and complement in the glomerular mesangium. 5 The precise role of this deposition in the pathogenesis of the mesangial lesion in these rats is unclear. However, the immunohistochemical alterations may well represent a marker for functional alterations in mesangial activity. With this marker it seemed possible to test the hypothesis that cure of the diabetic state in the rat by pancreatic islet transplantation could lead to reversal of the mesangial pathology.From the These studies were carried out in highly inbred Lewis rats (Microbiological Laboratories) weighing approximately 100 gm. at the start of the experiment. Experimental animals were made diabetic, following an eighteen-hour fast, by the injection of 65 mg. per kilogram of streptozotocin, intravenously and 2 ml. of 30 per cent glucose in water solution, intraperitoneally. Control animals were age-matched littermates. Induction of the diabetic state was confirmed by the development of a persistent, heavy glycosuria by Tes-Tape (Eli Lilly) and blood glucose levels in excess of 400 mg. per 100 ml. Diabetic and control rats were maintained on ad libitum water and Purina rat chow.From six to nine months following the induction of diabetes, each of nine diabetic rats received transplants of pancreatic tissue removed from eighteen to twenty-five newborn Lewis rats at two to seven days of age. 6 Briefly, the pancreases, which at this early age are high in islet tissue and low in acinar tissue and enzyme content, were finely minced and washed in Hank's balanced salt solution without glucose. They were then digested for forty minutes at 37°C. by agitation in 6 ml. of modified Puck's saline A (Gibco) containing 0.5 gm. per liter of trypsin and 0.2 gm. per liter EDTA with 30 mg. of added collagenase and then washed three times in Hank's solution. The recipient diabetic rat's peritone...

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Viable pancreatic islets were isolated from the pancreas of humans using modifications of the collagenase digestion and Ficoll gradient techniques. Gel filtration of tissue extracts following islet incubation in the presence of 3H-tryptophan indicated that radioactivity becomes incorporated into at least two islet pro teins. The larger of the two (LGI) has the approximate molecular size of proinsulin and the sm aller coelutes with glucagon as determined by column standardization. Radioimmunoassay of the gel filtration eluate for glucagon revealed that both molecules have glucagon immunoreactivity. Gel filtration in the presence of 8M urea did not alter the elution pattern of the LGI molecule. Polyacrylamide gel electrophoresis was performed on these glucagon immunoreactive molecules. The 3 H radioactivity and the glucagon immunoreactivity of the sm aller molecule were found to co-migrate electrophoretically with crystalline poreine glucagon and monodesamidoglucagon. With electrophoresis at high pH the electrophoretie mobility of the LGI molecule proved to be lower than that of glucagon. Partial tryptic degradation of the human LGI molecule yields 3H_ tryptophan labeled products having charge and immunologie characteristics indistinguishable from porcine glucagon and monodesamidoglucagon. Although further investigation is indicated, these results suggest that the human LGI molecule contains covalently bound glucagon and may thus serve as a precursor or an intermediate in human glucagon biosynthesis.