ABSTRACT
We report a case of congenital cystic adenomatoid malformation (CCAM) complicated by an esophageal duplication cyst in a 6-month-old girl. The patient presented with recurrent pneumonia. Magnetic resonance imaging revealed two cystic lesions in the upper and lower lobes of the right lung. After cystectomy, histopathological investigation revealed that the lower cyst was a CCAM Type I, and the upper cyst was an esophageal duplication cyst. The coexistence of these complex anomalies supports the concept that the esophageal duplication cyst is one entity of a broad spectrum of developmental abnormalities caused by abnormal budding of the primitive foregut.
Subject(s)
Cystic Adenomatoid Malformation of Lung, Congenital/complications , Esophageal Cyst/complications , Esophagus/pathology , Lung/pathology , Pneumonia/etiology , Cystic Adenomatoid Malformation of Lung, Congenital/diagnosis , Cystic Adenomatoid Malformation of Lung, Congenital/surgery , Esophageal Cyst/congenital , Esophageal Cyst/diagnosis , Esophageal Cyst/surgery , Esophagus/surgery , Female , Humans , Infant , Lung/surgeryABSTRACT
Glutamate dehydrogenase (GDH) is important in normal glucose homeostasis. Mutations of GDH result in hyperinsulinism/hyperammonemia syndrome. Using PCR/single-strand conformation polymorphism analysis of the gene encoding GDH in 12 Japanese patients with persistent hyperinsulinemic hypoglycemia of infancy (PHHI), we found a mutation (Y266C) in one PHHI patient. This mutation was not found in any of the control or type 2 diabetic subjects. The activity of the mutant GDH (GDH266C), expressed in COS-7 cells, was constitutively elevated, and allosteric regulations by ADP and GTP were severely impaired. The effect of the unregulated increase in GDH activity on insulin secretion was examined by overexpressing GDH266C in an insulinoma cell line, MIN6. Although glutamine alone did not stimulate insulin secretion from control MIN6-lacZ, it remarkably stimulated insulin secretion from MIN6-GDH266C. This finding suggests that constitutively activated GDH enhances oxidation of glutamate, which is intracellularly converted from glutamine to alpha-ketoglutarate, a tricarboxylic acid cycle substrate, which thereby stimulates insulin secretion. Interestingly, insulin secretion is also exaggerated significantly at low glucose concentrations (2 and 5 mmol/l) but not at higher glucose concentrations (8--25 mmol/l). Our results directly illustrate the importance of GDH in the regulation of insulin secretion from pancreatic beta-cells.
