Abstract
Summary Normal, metaplastic and carcinoma areas of seven stomachs resected for gastric carcinoma were examined morphologically, histochemically and biochemically. Metaplastic and carcinoma areas contained mainly non-sulphated acid and sulphated mucin, whereas normal areas contained almost exclusively neutral mucin as verified histochemically. The hexosamine-containing macromolecules present in different areas were isolated and characterized. They were divided into the following groups: 1) acid glycosaminoglycans, 2) high molecular weight glycopeptides and 3) low molecular weight glycopeptides. The concentration of saline-soluble type of chondroitin sulphate proteoglycan was higher in carcinoma areas than in normal or metaplastic areas, and the concentration of hyaluronate was higher in metaplastic areas than in normal or carcinoma areas. High molecular weight glycopeptides consisted mainly of glucosamine, galactosamine, fucose, galactose, variable amounts of sialic acids and sulphate and some amino acids. It seems apparent, that these carbohydrate components caused the characteristic staining properties of mucins in histochemical examinations. The total concentration of these glycopeptides was significantly lower in carcinoma areas than in normal or metaplastic areas. According to their anionic properties the high molecular weight glycopeptides were fractionated with aid of anion exchange chromatography into neutral and acid groups. The concentration of acid glycopeptides was significantly higher in metaplastic and carcinoma areas than in normal areas, where the high molecular weight glycopeptides were almost exclusively neutral. Acidity of glycopeptides was mainly caused by sialic acids, whereas the sulphation degree seemed to be quite low. The concentration of low molecular weight glycopeptides was approximately a half of total hexosamine containing substances. They consisted mainly of mdnnose, galactose, fucose, ribose, glucose, glucosamine and sialic acids. These apparently very heterogenous substances were not analyzed further.
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