We describe an unusual case of hypoglycemic syndrome in a 69-year old woman with a proinsulin-only secreting pancreatic endocrine adenoma. The clinical history was highly suggestive of an organic hypoglycemia, with normal or relatively low insulin concentrations and elevated proinsulin levels. Magnetic resonance and computed tomography of the abdomen showed a 1 cm pancreatic nodule and multiple...

Recent data suggest that proinsulin is associated with cardiovascular risk factors in nondiabetic and diabetic subjects. Since most conventional insulin assays cross-react with proinsulin, it has been suggested that the associations of insulin concentrations with dyslipidemia and hypertension could actually reflect associations with proinsulin. We examined these associations by using both a con...

Proinsulin, the precursor of insulin and C-peptide, is detectable in the circulation and is a potential marker of beta-cell dysfunction. Currently, circulating proinsulin can be measured accurately without the interference of insulin or C-peptide by immunometric assays and a few specific radioimmunoassays. An immunochemiluminometric assay was developed in our laboratory by using two immunopurif...

Paternal mutation of ATP-sensitive K(+) (K(ATP)) channel genes and loss of heterozygosity (LOH) of the 11p15 region including the maternal alleles of ABCC8, IGF2, and CDKN1C characterize the focal form of persistent hyperinsulinemic hypoglycemia of infancy (FoPHHI). We aimed to understand the actual nature of FoPHHI in comparison with insulinoma. In FoPHHI, the lesion consists in clusters of be...

The cobalt(II)-substituted proinsulin and insulin hexamers have been studied in solution via electronic absorption spectroscopy. Hexameric proinsulin is shown to undergo the phenol-induced T6 to R6 conformational transition in a manner analogous to that previously established for insulin. In the absence of coordinating anions, the coordination spheres of the Co(II) ions in the proinsulin and in...

OBJECTIVE Chronic exposure to calcineurin inhibitors and corticosteroids poses renal transplant recipients (RTR) at high risk for development of new-onset diabetes after transplantation (NODAT). Pancreatic β-cell dysfunction may be crucial to the pathophysiology of NODAT and specific markers for β-cell dysfunction may have additive value for predicting NODAT in this population. Therefore, we pr...

Hyperinsulinemia is associated with the development of coronary heart disease. However, the underlying mechanisms are still poorly understood. Hypercoagulability and impaired fibrinolysis are possible candidates linking hyperinsulinism with atherosclerotic disease, and it has been suggested that proinsulin rather than insulin is the crucial pathophysiological agent. The aim of this study was to...

Insulin biosynthesis in the brown bullhead, Ictalurus nebulosus (Le Sueur), was studied by measuring the incorporation in vitro of [(3)H]leucine into proteins of the principal islet. The tissue was incubated for 6-15h in Krebs-Ringer bicarbonate buffer with [(3)H]leucine, supplemented with amino acids and glucose. Proteins, precipitated with trichloroacetic acid and extracted with acid ethanol,...