Diabetes
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We found the rare properdin factor B(Bf) variant F1 to be present in 11% of 72 patients suffering from insulin-dependent diabetes (IDDM) compared with 2% among 150 normal controls. BfF1 thus confers a relative risk for IDDM of 5.55. ⋯ Studies of unselected families with one or more affected members suggest that the B18, BfF1 does not necessarily segregate with IDDM phenotype. This study provides further evidence for the genetic heterogeneity of IDDM.
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The effect of 16- and 48-h fasting on pancreatic somatostatin, insulin, and glucagon secretion was studied, using the isolated perfused rat pancreas. In the presence of 4.4 mM glucose, basal somatostatin and insulin concentrations in the perfusate were significantly lower in 48-h fasted rats than in fed animals, whereas basal glucagon secretion was significantly elevated in fasted rats. ⋯ Insulin and glucagon secretion also changed during the fasting. These results suggest that not only insulin and glucagon, but also somatostatin contribute to nutrient homeostasis.
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Case Reports
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. ⋯ 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.
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Cell fractionation, enzyme analysis, and electron microscopy were used to study the effects of streptozotocin-induced diabetes and insulin replacement on liver structure and function. In liver homogenates from diabetic rats, glucose-6-phosphatase (G-6-Pase) activity was stimulated about 2 1/2-fold over that found in normal animals. Analyses of isolated rough and smooth microsomes from diabetic rats for G-6-Pase activity showed a fourfold increase in the smooth microsomes and a small increase in enzyme activity in rough microsomes when compared with these fractions from control animals. ⋯ We interpret these results to indicate that diabetes causes hepatocytes to form additional smooth endoplasmic reticulum with specialized membranes, at least with respect to G-6-Pase. It is suggested that this cellular specialization is a response of the hepatocyte to the diabetic state, namely, a demand for increased hepatic glucose production and release into the blood stream, thus contributing to the hyperglycemia characteristic of this disease. Insulin administration to the diabetic animals reverses the above alterations.