We investigated the expression and changes in the intracellular localization of a 72-kDa heat shock protein (HSP72) in rat gastric pyloric and fundic mucosa before and after water-immersion stress. Severe mucosal damage was found in the fundic mucosal area of the stomach after this stress. However, no mucosal lesion developed in the pyloric mucosal area. HSP72 in both the soluble and insoluble fractions of the pyloric and the fundic mucosal areas was significantly increased after water-immersion stress, peaking 6h after the initiation of the stress. The increase in HSP72 was more significant in the pyloric mucosal area than in the fundic mucosal area under both normal and stress conditions. The increase of HSP72 in the pyloric mucosal cells occurred prior to the formation of the mucosal lesions, whereas the increase of HSP72 in the fundic mucosal cells was observed after ulcer formation. An immunohistochemical study showed that HSP72 was constitutively expressed in the cytoplasm of the gastric mucosal cells, and that the intranuclear induction of HSP72 was remarkably intense in the pyloric mucosal cells, especially in the proliferative zone, compared with the fundic mucosal cells. Our results may suggest that HSP72 has an important cytoprotective function in gastric mucosal cells and that there is a "biophysical" difference between pyloric and the fundic mucosal cells.

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Objects Ultrashort‐segment Barrett’s esophagus (USSBE; length of <1 cm) is very frequently diagnosed in Japan, but the cancer risk of USSBE is unknown. In this study, by retrieving endoscopic images, we retrospectively investigated the incidence of esophageal adenocarcinoma (EAC) by the grade of Barrett’s esophagus (BE) and compared the findings with those of gastric cancer by the degree of endoscopic gastric atrophy in the same population. Methods Among consecutive participants who had undergone endoscopy for an annual health checkup in 2014, the 9121 who had received at least one follow‐up endoscopy by December 2020 were enrolled in this study. Using the retrieved endoscopic images, we retrospectively evaluated BE and gastric atrophy. Information on the subsequent occurrence of EAC and gastric cancer as of December 2020 was also collected. The incidence of cancer by the extent of BE and gastric atrophy was calculated and expressed as the percentage per year. Results On reviewing the endoscopic image in 2014, 4190 (45.9%) were found to have been diagnosed with BE, of whom 3318 (36.4%) were judged to have USSBE. During an observation period of 54.1 (17.9) months, 89 gastric cancers and only two EACs were identified. The incidence of EAC in USSBE was 0.0068%/year, which was nearly as low as the incidence of gastric cancer in atrophy‐free patients (0.0068% vs. 0.0059%/year). Conclusions Although the prevalence of USSBE is quite high (36.4%), the incidence of EAC in USSBE is very low (0.0068%/year). Accordingly, USSBE can be excluded from targets for endoscopic surveillance in Japan.

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