A novel method for detecting single glandular intestinal metaplasia in themucosal surface of the fixed stomach using methylene blue

A close association between intestinal metaplasia of the stomach and the we ll-differentiated type of gastric cancer is well recognized. The etiologica l relationship and how intestinal metaplasia contributes to gastric carcino genesis are, however, still unclear. In order to answer this question, prec ise mapping and identification of the smallest lesion of intestinal metapla sia are desired. Establishment of an accurate and easy method for detecting intestinal metaplasia was the goal of this study. Surgical specimens of st omachs resected for gastric cancer were used. The specimens were stained wi th methylene blue, an oxidation-reduction marker, in whole mount, after fix ation with 4% paraformaldehyde in 0.1 M phosphate buffer (pH 7.4), and obse rved under a stereomicroscope. Normal gastric mucosa was stained blue, wher eas intestinal metaplasia mucosa was not stained and had white or sky-blue island-like features. Intestinal metaplasia of complete type was unstained and showed white island-like features, while intestinal metaplasia of incom plete type showed sky-blue staining. With this method, we were able to dete ct even intestinal metaplasia composed of a single gland, when the intestin al metaplasia was of complete type. When stomach samples were stained in th e presence of diphenyleneiodonium chloride (DPI), an inhibitor of nicotinea mide adenine dinucleotide phosphate reduced form (NADPH) reductase, all the samples were homogeneously stained blue. Loss of the color of methylene bl ue was caused by the reductase activity of NADPH reductase, which is strong ly and specifically expressed in intestinal metaplasia. A novel method for deterring intestinal metaplasia, even a single gland, was established.