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Biomedical subjects

A J Matas

Publications and source records attributed to A J Matas.

At least 325 records · Page 18Linked to original sources
PubMed1980

Total or near total pancreatectomy and islet autotransplantation for treatment of chronic pancreatitis.

Total or near total pancreatectomy is the surest way to relieve the pain of chronic pancreatitis but is rarely applied because the metabolic consequences are so severe. For most patients drainage procedures are applicable, but pancreatectomy may be the only alternative for small duct disease or where procedures to improve duct drainage have failed. Preservation of endocrine function is a major problem in patients who require pancreatectomy. Experiments in pancreatectomized dogs have shown that intrasplenic or intraportal transplantation of unpurified pancreatic islet tissue dispersed by collagenase digestion can prevent diabetes. We have applied this technique to ten patients with chronic pancreatitis, small ducts, and intractable pain. The entire pancreas of > 95% of the pancrease was excised, minced, dispersed by collagenase digestion and infused into the portal vein < 2 1/2 hours after removal. Mean (+/- SD) rise in portal pressure was 17 +/- 8 cm of water. Liver function tests were altered minimally. All patients were relieved of pain. One patient died of a complication not related to the islet autotransplant; viable islets were identified in the liver at autopsy. Of the remaining nine patients, three have been insulin independent for 1, 9, and 38 months. One patient was insulin indpendent for 15 months and now takes 12 units of insulin daily. Three have nonketosis prone diabetes (tested by insulin withdrawal) and take 15--30 units of insulin per day. C-peptide studies in these patients show that functioning islets are present. Two patients are diabetic and require 35 and 60 units of insulin per day. In eight of nine patients tested serum insulin concentrations fell to undetectable levels during the interval between pancreatectomy and islet transplantation. Serum insulin levels during the first few hours after islet transplantation predicted success. In the insulin independent or in the patients with mild diabetes, insulin levels were persistently greater than or equal to 6 microU/ml. In the other two patients, the increase in insulin concentration was not sustained. Islet tissue preparation from a diseased pancreas is difficult. The surgeon and the patient must still be willing to accept diabetes for relief of pain when performing this operation. In some patients, however, islet autotransplantation can prevent or partially ameliorate diabetes after pancreatectomy, and preservation of endocrine function is worthwhile.

Adult↗
PubMed1980

Transplantation of dispersed pancreatic islet tissue in humans: autografts and allografts.

Islet transplantation is successful in animals and holds considerable promise as endocrine replacement therapy for patients with diabetes mellitus, but clinical application to diabetic patients has been difficult. We have shown the technical feasibility of human islet transplantation by autotransplantation of dispersed pancreatic islet tissue into the portal vein in three patients with chronic pancreatitis and incapacitating, intractable pain who underwent near-total (greater than 97%) pancreatectomy. In all three patients, the excised pancreas was dispersed by collagenase digestion, but no effort was made to purify the islets. Islet yield, as judged by tissue insulin content, ranged from 24 to 55%. The first patient, who never received insulin after the pancreatectomy and islet autotransplantation, had a normal oral glucose tolerance test by 3 wk and has remained normoglycemic for over 2 yr. In the second patient, viable islets were histologically identified in the liver parenchyma. The third patient was treated with hyperalimentation for 3 wk after the pancreatectomy and islet autotransplantation and, during this period, required insulin. After cessation of hyperalimentation and initiation of oral geedings, the patient was withdrawn from insulin. Although abnormalities of carbohydrate metabolism were present, the patient did not require insulin for more than 1 yr. Seven diabetic renal allograft recipients have received allografts of dispersed pancreatic islet tissue prepared in the same way. No patients were cured of diabetes, although transient evidence of islet function--increase in serum or urinary C-peptide levels or decrease in exogenous insulin requirements--occurred in some. Although rejection was probably responsible for most of the failures, transplantation of allogeneic human islet tissue as a free graft is metabolically inefficient. With the current state of immunosuppressive therapy, the primary role of islet transplantation may be in a situation where rejection cannot occur: as an autograft to obviate the occurrence of diabetes after extensive pancreatectomy for benign disease.

Adult↗
PubMed1979

DL-ethionine treatment of adult pancreatic donors. Amelioration of diabetes in multiple recipients withe tissue from a single donor.

Transplantation of adult rat pancreatic islet tissue as a free graft requires the separation of islet from exocrine tissue to avoid host injury or graft destruction by digestive enzymes. The poor yield from islet isolation techniques currently necessitates the use of multiple donors to ameliorate diabetes in a single recipient. DL-ethionine (DLE) is an agent selectively toxic to the exocrine pancreas. We examined the effect of DLE administration on pancreatic digestive enzyme content and islet mass in adult Lewis rats and the ability of such pancreatic tissue dispersed by collagenase digestion without specific islet isolation to ameliorate diabetes when transplanted to the portal vein of syngeneic rats with streptozotocin induced diabetes. Rats fed normal chow supplemented with 0.5% DLE for 14-20 days showed a logarithmic loss of pancreatic mass. Total pancreatic amylase content declined to 0.3 + 0.1 mg, less than 3% of control values (14.3 +/- 1.0 mg). Total insulin content in DLE treated rats was 87 +/- 8 microg, not significantly different from control rats (101 +/- 7 microg). Histological examination confirmed the selective atrophy of exocrine tissue in DLE treated rats. Fresh pancreatic tissue prepared from a single DLE treated donor ameliorated diabetes 75% of the time when transplanted to one or two recipients and 65% of the time when divided between three of four recipients. Tissue prepared from a single DLE treated donor and stored for 24-48 hours ameliorated diabetes 91% of the time when divided between one or two recipients. Only four of 31 diabetic rats transplanted with fresh pancreatic tissue from untreated adult donors became normoglycemic. Pretreatment of adult rats with DLE induces selective exocrine atrophy, permits dispersed pancreatic tissue from a single donor to ameliorate experimental diabetes in up to four recipients, and allows tissue to be preserved by culture for up to 48 hours without specific islet isolation.

Amylases↗
PubMed1979

Encephalomyocarditis virus-induced diabetes mellitus treated by islet transplantation.

There is considerable evidence that at least some cases of juvenile onset diabetes mellitus in humans are a result of viral infection. Viral-induced diabetes in mice may provide an experimental counterpart more similar to the clinical situation than chemical-induced diabetes. Our experiments in such mice indicate that islet transplantation is effective in ameliorating viral-induced diabetes and is encouraging for ultimate clinical application of islet transplantation to juvenile onset insulin-dependent diabetics. In addition, our results show that islets in ectopic sites outside of the pancreas are resistant to damage induced by primary viral infection. The mechanism of this resistance is obscure and will be the subject of future investigations.

Animals↗
PubMed1979

Glomerular basement membrane thickness following islet transplantation in the diabetic rat.

Glomerular basement membrane (GBM) thickness was measured in diabetic rats prior to and following islet transplantation. Over the course of the experiment (from 7 to 13 months of diabetes) GBM thickness in diabetic animals exceeded that of littermate controls. After 7 months of diabetes a group of animals received successful intraportal transplants of neonatal pancreatic tissue. GBM thickness at 2 and 6 months following islet transplantation matched the thickness in nontransplanted diabetic rats and exceeded that in control animals. Failure to reverse GBM thickening in diabetic rats following islet transplantation may be due to very slow rates of GBM tunover in the rat. Previous work has demonstrated normalization of urinary albumin excretion after islet transplantation, suggesting that GBM thickening, per se, is not a significant factor causing albuminuria in rats with longstanding diabetes.

Animals↗