Neuroendocrine carcinoma arising from Barrett's esophageal adenocarcinoma: a case report.

Neuroendocrine carcinoma in Barrett's esophagus is rare and its developmental mechanisms remain unclear. Neuroendocrine carcinoma arising in Barrett's esophagus with adenocarcinoma was detected at an early stage and resected by endoscopic submucosal dissection. Detailed pathological examination revealed that the neuroendocrine carcinoma originated via differentiation of the preexisting adenocarcinoma. A 79-year-old man presented with a flat protruding lesion in the esophagogastric junction. Esophagogastroduodenoscopy revealed a red flat 10-mm protruding lesion in the Barrett's epithelium and a shallow depression at the distal end. Narrow band imaging with magnification showed that the blood vessels in the protrusion were dilated and meandered irregularly, while those in the depression were small and did not form a network; the blood vessels were missing in some parts of the depression. Well-differentiated adenocarcinoma was diagnosed after analysis of the biopsy specimen of the protrusion, and endoscopic submucosal dissection was performed. The pathological diagnosis was neuroendocrine carcinoma with an adenocarcinoma component.

Efficient production of recombinant PP2A at a low temperature using a baculovirus expression system.

Protein phosphatase 2A (PP2A) is an enzyme useful for detecting several natural toxins represented by okadaic acid and microcystins. We found that the production of the recombinant human PP2A catalytic subunit (rhPP2Ac) in High Five insect cells could markedly increase when the cells were cultured at 19 °C instead of 27 °C used under conventional conditions. The yield and purity of the enzyme increased four- and three-folds, respectively. The benefit of the altered culturing temperature was observed with the recombinant human protein phosphatase 2B but not 2Cα. The different responses among the enzymes suggest the involvement of an enzyme-specific mechanism that leads to the catalytic subunit overexpression. This is the first report to produce rhPP2Ac at a temperature lower than that used under conventional culture conditions (27 °C) used in the baculovirus expression system with High Five insect cells.