[18F]FB(ePEG12)12-exendin-4 noninvasive imaging of insulinoma negative for insulin immunostaining on specimen from endoscopic ultrasonography-guided fine needle aspiration: a case report with review of literature.

Insulinomas are the most common functional pancreatic neuroendocrine neoplasm; when treatment is delayed, they induce hyperinsulinemic hypoglycemia, which is life-threatening. As surgical resection is the only curative treatment for insulinoma, preoperative localization is crucial; however, localization based on conventional imaging modalities such as computed tomography (CT) and magnetic resonance imaging is often inconclusive. Somatostatin receptor-targeted imaging is another option for detecting pancreatic neuroendocrine neoplasms but has low sensitivity and is not specific for insulinoma. The clinical application of other localizing approaches such as selective arterial calcium stimulation and endoscopic ultrasonography-guided fine needle aspiration (EUS-FNA) is limited by their being invasive and/or technically complex. Moreover, an EUS-FNA specimen of an insulinoma may be negative on insulin immunostaining. Thus, a noninvasive and clinically practical insulinoma-specific diagnostic tool to discriminate insulinomas with high accuracy is anticipated. Glucagon-like peptide-1 receptor (GLP-1R)-targeted imaging has emerged in the effort to fulfill this need. We recently developed the novel fluorine-18-labeled exendin-4-based probe conjugated with polyethylene glycol, [18F]FB(ePEG12)12-exendin-4 (18F-exendin-4) for positron emission tomography (PET) imaging and reported its clinical benefit in a case of insulinoma in the pancreatic tail. We report here a case of insulinoma in the pancreatic head in which an EUS-FNA specimen was negative on insulin immunostaining while precise preoperative localization and conclusive evidence for curative enucleation was provided by 18F-exendin-4 PET/CT (Japan Registry of Clinical Trials; jRCTs051200156).

Bio-based hydrogels prepared by cross-linking of microbial poly(gamma-glutamic acid) with various saccharides.

Novel bio-based hydrogels were prepared by cross-linking of microbial poly(gamma-glutamic acid) (PGA) with saccharides such as glucose, maltotriose, and cyclodextrin (CD) in the presence of water-soluble carbodiimide in dimethyl sulfoxide (DMSO) by one-pot synthesis at 25 degrees C for 24 h. The degradation of the gels in alkaline solution (pH 9) at 37 degrees C was also investigated. The PGA gels cross-linked with various neutral saccharides were obtained in relatively high recovery yields by use of a base like 4,4-(dimethylamino)pyridine. The PGA gel cross-linked by glucose showed the highest water absorption of 3000 g/g. The PGA gels cross-linked by CDs showed higher water absorption than those cross-linked by the corresponding linear saccharides. It was revealed that the water absorption of the PGA gel was affected by the cross-linker content and also the structure of cross-linkers as they had an effect on the cross-linking density of the PGA gel. The PGA gels were hydrolyzed under alkaline condition (pH 9) at 37 degrees C. The degradation rate was higher when the cross-linker content of the gel was lower.