Four families with hyperproinsulinemia found in Japan were described. The details of the first case, who was investigated by Kanazawa et al., were reported and the similarity of the first case to the following cases was shown. Arginine 65 of the proinsulin molecule might be a hot spot of the insulin gene. A possible abnormality of insulin release in affected individuals was disclosed by investigation of the family members of the first case.
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http://dx.doi.org/10.1016/0168-8227(94)90241-0 | DOI Listing |
Clin Med Insights Case Rep
September 2021
Center for Diabetes, Shin-suma General Hospital, Kobe, Japan.
Introduction: Insulin is synthesized in the β-cells from preproinsulin. Preproinsulin becomes proinsulin after leaving the signal peptide. Proinsulin is separated into C-peptide and insulin by 2 enzymes.
View Article and Find Full Text PDFEndocr J
April 2015
Third Department of Internal Medicine, Division of Diabetes, Endocrinology and Metabolism, Kyorin University School of Medicine, Tokyo 181-8611, Japan.
Type 2 diabetic (T2D) patients exhibit fasting relative hyperproinsulinemia owing to pancreatic β-cell dysfunction. To clarify the mechanism underlying this hyperproinsulinemic state, we evaluated the activities of the endopeptidases prohormone convertase (PC) 1/3 and PC2 in T2D patients. Fasting blood levels of intact proinsulin (IPI), total proinsulin (t-PI) and C-peptide were measured simultaneously, and intravenous glucagon loading was performed to investigate the dynamics of circulating proinsulin-related molecules released from pancreatic β-cells in 12 healthy volunteers and 18 T2D patients.
View Article and Find Full Text PDFJ Diabetes Investig
April 2011
Research Center of Rural Medicine, Nachi-Katsuura Spa Hospital, Wakayama, Japan.
Some mutations of the insulin gene cause hyperinsulinemia or hyperproinsulinemia. Replacement of biologically important amino acid leads to defective receptor binding, longer half-life and hyperinsulinemia. Three mutant insulins have been identified: (i) insulin Chicago (F49L or PheB25Leu); (ii) insulin Los Angeles (F48S or PheB24Ser); (iii) and insulin Wakayama (V92L or ValA3Leu).
View Article and Find Full Text PDFEndocr J
December 2000
Department of Medicine and Bioregulatory Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
It is established that disproportionately elevated plasma proinsulin levels occur in patients with Type 2 diabetes. In the present study, multivariate analysis was performed to determine what factors contributed to the disproportionately elevated plasma proinsulin levels in Japanese patients with Type 2 diabetes (n=276). Results from univariate analysis showed that both fasting proinsulin/C-peptide ratio and proinsulin/IRI ratio were approximately 2-fold higher in patients with Type 2 diabetes than those in healthy nondiabetic subjects (n=45).
View Article and Find Full Text PDFInt J Pancreatol
February 1999
Department of Surgery, Osaka Municipal Juso-Shimin Hospital, Japan.
Hypoglycemia with a low serum immunoreactive insulin (IRI) level and serum immunoreactive C-peptide (IRC) level was found in a 74-yr-old female. Although a fasting test induced hypoglycemia, the responses of IRI and IRC during the fasting test, and the results of a glucose tolerance test, glucagon test, and secretin test did not indicate the presence of an insulinoma. However, the serum proinsulin level before the fasting test was 130.
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