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Biomedical subjects

C Ricordi

Publications and source records attributed to C Ricordi.

At least 271 records · Page 15Linked to original sources
PubMed1991

Abnormal sensitivity to glucose of human islets cultured in a high glucose medium: partial reversibility after an additional culture in a normal glucose medium.

In the experimental animal chronic hyperglycemia alters the islet's sensitivity to glucose. In the present study the glucose sensitivity of human pancreatic islets, isolated and purified, obtained from seven human pancreases using an automated method was evaluated. After a 12-h stabilization period, islets were cultured for 48 h in normal (5.5 mmol/L) or high glucose (16.7 mmol/L) medium. Islets were then perifused to study their insulin response to glucose. Islets cultured in the high glucose medium lost glucose-induced insulin release and, when challenged with an acute fall of glucose concentration in the perifusate, showed a paradoxical insulin release. Insulin release in response to 10 mmol/L L-arginine was preserved in these islets, suggesting a selective reduction of the insulin response to glucose. An additional 48-h culture in 5.5 mmol/L glucose medium partially restored the sensitivity to glucose of the previously unresponsive islets. These findings indicate that short term exposure to high glucose concentrations induces a selective glucose insensitivity of human islets, which can be partially reversed by an additional culture in normal glucose medium.

Arginine↗
PubMed1990

Pancreatic islet transplantation after upper abdominal exenteration and liver replacement.

Nine patients who became diabetic after upper-abdominal exenteration and liver transplantation were given pancreatic islet-cell grafts obtained from the liver donor (eight cases), a third-party donor (one), or both (four). Two patients were diabetic when they died of infections after 48 and 109 days, as was a third patient who died of tumour recurrence after 178 days. The other 6 are alive 101-186 days postoperatively, and five are insulin-free or on insulin only during night-time parenteral alimentation. C-peptide increased 1.7 to 3.3 fold in response to intravenous glucose in these five patients who have had glycosylated haemoglobin in the high normal range. However, the kinetics of the C-peptide responses to intravenous glucose in all eight patients tested revealed an absent first-phase release and a delayed peak response consistent with transplantation and/or engraftment of a suboptimal islet cell mass. The longest survivor, who requires neither parenteral alimentation nor insulin, is the first unequivocal example of successful clinical islet-cell transplantation.

Abdomen↗
PubMed1990

Transplantation of parathyroid, adrenal cortex and adrenal medulla using procedures which successfully prolonged islet allograft survival.

Life-long hormone replacement therapy is today the only form of therapy for several endocrine insufficiencies. Transplantation of endocrine tissues could represent a more physiological approach to the treatment of different syndromes such as adrenal insufficiency, diabetes or hypoparathyroidism. Successful experimental islet transplantation across major histocompatibility barriers using cultural pretreatment of the insulin producing tissue in conjunction with temporary immunosuppression of the recipients, encouraged us to attempt similar approaches with parathyroids, adrenal cortex and adrenal medulla. Either bilateral parathyroidectomy or bilateral adrenalectomy were performed on the recipient rats before transplantation, followed by the implantation of parathyroid, adrenal cortical or adrenal medullary tissue beneath the renal capsule. The tissue was transplanted either immediately after its dissection or after pretreatment with 1 week culture. Some of the recipients received a short term cyclosporine treatment. The results indicated that parathyroid and adrenal medulla transplants were often infiltrated by mononuclear cells 30 days after transplantation. In contrast, adrenal cortical tissue was well preserved 4 weeks after transplantation, without showing any sign of rejection when a combination of pre-transplant culture of the adrenal tissue and temporary cyclosporine treatment of the recipients was used.

Adrenal Cortex↗
PubMed1990

Swine islet isolation and transplantation.

An isolation procedure for large scale isolation of swine islets is described. The results from 15 consecutive isolations are reported. The glands were excised from heart beating animals with no warm ischemia time. The pancreases were digested by a modification of the automated method for human islet isolation. It was possible to separate an average of 690,000 +/- 279,429 islets per pancreas corresponding to 10,360 +/- 4034 islets for gram of pancreas with a volume of 714 +/- 480 mm3. After purification the recovery was 255,000 +/- 32,407 islets corresponding to 4,000 +/- 567 islets per gram of pancreas. Purity of the final preparation was 80-95% islets. Insulin content resulted in an average of 146.8 +/- 78 U before purification and 71 +/- 53 after purification. After transplantation of an aliquot of the final preparation in diabetic nude mice normoglycemia occurred in six mice. 30 days after transplantation nephrectomy of the kidneys bearing the grafts produced a rapid return to the diabetic state in all cases.

Animals↗
PubMed1990

Selection of donors significantly improves pig islet isolation yield.

The purpose of the present study was to test the influence of donor age on islet isolation yield in swines. Large White pigs of 10 months (group 1, n = 10) and 2-3 years (group 2, n = 5) were used. A modification of the automated method for human islet isolation was used for pig islet separation. After ductal injection of a collagenase solution (Seromed, type C-1000) the islets were separated through a continuous digestion process. In group 1 it was possible to obtain an average of 636,100 islets (volume = 476.1 mm3, insulin content = 101.4 Units). In group 2 the average total islet number was 799,800 representing a volume of 1190.6 mm3 (Insulin content 210 Units). Total islet number was not significantly different in the two groups, however when islet volume and total insulin content were considered, older animals allowed a significantly higher yield (P less than 0.01 for volume and P less than 0.05 for insulin content). These findings indicate that it is possible to separate large number of pig islets from both young (10 months) and older (2-3 years) animals and that selection of donor pigs will improve islet isolation yield. These results may be of assistance in the definition of requirements for more effective islet isolation in swines.

Animals↗
PubMed1990

Isolation of the elusive pig islet.

This study describes a procedure for large scale isolation of swine islets. The reported results are from 15 consecutive isolations. The glands were removed from live animals with no warm ischemia, and the pancreata were digested by a modification of the automated method for human islet isolation. It was possible to separate an average of 690,000 +/- 279,429 islets per pancreas corresponding to 10,360 +/- 4034 islets per gram of pancreas with a volume of 714 +/- 480 mm3. After purification the recovery was 255,000 +/- 32,407 islets corresponding to 4,000 +/- 567 islets per gram of pancreas. Purity of the final preparation was 80% to 95% islets. Insulin content resulted in an average of 146.8 +/- 78 U before purification and 71 +/- 53 U after purification. After a 10 mm3 aliquot of the final preparation was transplanted under the renal subcapsular space of seven nude mice with diabetes, normoglycemia occurred in six of the mice. Thirty days after transplantation, nephrectomy of the kidneys bearing the grafts produced a rapid return to the diabetic state in all cases. This method makes it possible to provide large numbers of intact swine islets for preliminary studies of prevention of the rejection of pig islet xenograft by immunoalteration and immunoisolation procedures.

Animals↗