A comparative study of the major glycoprotein isolated from normal and neoplastic gastric mucosa

Ultrastructural distribution of lectin-binding sites on gastric superficial mucus-secreting epithelial cells. The role of Golgi apparatus in the initial glycosylation

Normal human gastric epithelial cells were examined by electron microscopy using each of five biotinylated lectins [Ulex europaeus agglutinin I (UEA-I), peanut agglutinin (PNA), wheat germ agglutinin (WGA), soybean agglutinin (SBA) and Dolichos biflorus agglutinin (DBA)] as a probe. We employed 35 gastric surgical specimens removed from complicated peptic disease. The lectin-binding sites were revealed with streptavidin-colloidal gold complex. All specimens were embedded in Spurr and LR White resins. In superficial foveolar epithelial cells, the lectins used were generally positive in all cell types (mainly UEA-1 and PNA) on the Golgi region and mucus cytoplasmic vacuoles, with many variations among cells in the same case. On the other hand, extracellular mucus was negative for WGA. Labelling with PNA revealed a biphasic pattern (peripheral positivity) on mucous droplets in surface and foveolar cells. The cis side of the Golgi apparatus was labelled with SBA and PNA and rough endoplasmic reticulum with SBA (only five cases). Lectin-binding variability could be related to heterogeneous composition of gastric mucus. Our results with SBA suggest initiation of O-glycosylation at the Golgi apparatus; however a role of the rough endoplasmic reticulum cannot be excluded (N-glycosylation). We propose the following sequence of sugar addition to the carbohydrate side-chains of gastric glycoproteins: (1) GaNAc (Golgi apparatus cis-side), (2) GlcNAc (Golgi apparatus intermediate face), (3) GalNac or Gal, alpha-L-fucose (Golgi apparatus trans-side).

ABO (H) blood group antigen expression in gastric mucosa

The A, B, O (H) blood group antigens (BGA) are glycolipids present in the plasma membranes of many different epithelial cells. Alterations in BGA expression have been described in malignant tumors and premalignant lesions. We have studied ABO (H) BGA expression in paraffin sections of gastric specimens using immunofluorescence techniques with monoclonal antibodies. 102 patients were studied. 15 with normal mucosa (NM); 16 with duodenal ulcer (DU); 23 with gastric ulcer (GU); 11 with pernicious anaemia (PA) and 37 with adenocarcinoma (AC). The expression of BGA in normal gastric mucosa is detected in surface epithelium, mucoid cell neck glands and parietal cells as well as 2/3 of antral glands. BGA expression in DU gastritis is very similar to that seen in NM. In atrophic chronic gastritis associated with GU and PA there is a significant decrease in BGA expression. In patients with PA, BGA expression is greater in antral mucosa than in fundic mucosa. Loss of BGA expression is more pronounced in atrophic chronic gastritis surrounding AC. Intestinal metaplasia shows variable BGA expression. Our results support the hypothesis that loss of BGA expression by epithelial gastric mucosal cells may be related to alterations in cellular differentiation and premalignant potential.

Organ specific antigens of the human gastrointestinal tract

We previously reported the characterization of a normal adult colonic mucin antigen which contained an organ specific immunodeterminant [Tissue Antigen 11, 362 (1978)]. In the present study we have investigated mucins produced at other levels of the gastrointestinal tract in order to determine if regional specificities exist. Mucins were isolated from normal adult stomach, jejunum, ileum and colon and used to prepare antisera in rabbits. By radioimmunoassay at least four distinct specificities were observed. Gastric, ileal and colonic mucins were shown to contain immunodeterminants which were organ specific. Antiserum directed toward jejunal mucin determinants was reactive with the entire gastrointestinal tract. However, by heterologous inhibition analyses employing purified mucins as inhibiting antigens, the anti-jejunum antiserum was shown to be capable of discriminating a determinant present in much higher epitope density within small intestinal mucins as compared to mucins of the stomach and colon. Thus, it appeared that immunologic determinants present within mucin type glycoproteins of the gastrointestinal tissues exhibit anatomic specificity. In each case the structure of the immunodeterminant was, or was dependent upon the presence of a sialic acid derivative.

Lectin binding to human gastric adenocarcinomas and adjacent tissues

The binding of lectins to paraffin sections of nine gastric carcinomas and adjacent mucosa was examined by fluorescence microscopy. A battery of nine lectins was employed, and both intestinal and diffusely infiltrating tumors were tested. Wheat germ agglutinin and Ricinus communis agglutinin I appeared to bind to both mucus and nonmucus glycoproteins; these lectins labeled tumor cells, benign epithelial cells, and nonepithelial tissues strongly and consistently. Peanut agglutin, soybean agglutinin, Dolichos biflorus agglutinin, Bandeiraea simpifolica agglutinin, and Ulex europaeus agglutinin I bound extensively to mucosubstances in vacuoles and apices of benign epithelial cells but often bound to tumor cells focally and in some cases not at all. Neuraminidase digestion enhanced lectin staining in some tumors; but in others, especially those of the diffusely infiltrating type, neuraminidase digestion did not enhance the staining of tumor cells. The results suggest that the decrease in the proportion of tumor cells labeling with lectin relative to superficial epithelial cells can be due either to the oversialylation of mucoproteins or to the loss of glycosylating enzyme activity. Concanavalin A did not bind to mucosubstances in the vacuoles or apices of benign epithelium, but bound to mucus vacuoles of metaplastic epithelium and to coarse cytoplasmic granules in two of the tumors examined. This suggests either the abnormal addition of mannose to mucus glycoprotein or the production of a distinct glycoprotein by some gastric tumors.

Changes in the Incorporating Activity of 35S-Sulfate into Gastric Sulfated Glycoproteins in the Rat with Erosions by Restraint and Water Immersion Stress

The synthetic activity of rat gastric sulfated glycoproteins (SGP) in vitro was investigated at various time intervals after water immersion stress using 35S-sulfate as a precursor. More than 90 percent of the total radioactivity was incorporated into mucosal SGP, and the rest was incorporated into glycosaminoglycans in the gastric muscular layer. The incorporation of 35S-sulfate into SGP increased at 2 hr and decreased at 6 hr after the onset of stress. The incorporating activity again increased markedly at 12 hr and then recovered to the normal level at 24 hr after the onset of stress. An anti-ulcer agent, N-(N-acetyl-beta-alanyl)-L-histidine aluminum complex (AAHA), significantly increased the SGP synthetic activity at 12 hr and at 24 hr after the onset of stress. It was indicated from the elution patterns on the DEAE-cellulose column that AAHA increased the amount of highly sulfated glycoproteins compared with the stress control at 12 hr after the onset of stress. The uronic acid content in the gastric muscular layer of the rat was unchanged with stress. These results in the in vitro experiment indicate that the SGP synthetic activity does not decrease with stress load, but rather increases at 2 hr and at 12 hr after the onset of stress when a sufficient amount of 35S-sulfate is supplied. Accordingly, it is suggested that SGP facilitates the restoration of the gastric mucosal damage caused by stress.

The glycosaminoglycans of pig colonic wall connective tissue

Colon wall from pig, stripped of most of the mucosal layer to leave material largely composed of muscle, basement membrane, and extracellular matrix, was subjected to procedures for isolation of glycosaminoglycans. A total ethanol precipitate from a papain digest was fractionated by selective ethanol precipitation in the presence of Ca2+. Glycosaminoglycan fractions, freed proteolytically from a high molecular weight glycoprotein component, were further purified by Sepharose CL-6B gel-filtration or DE-52 anion-exchange chromatography. Glycosaminoglycans were identified by chemical composition, 13C-NMR spectroscopy and response to chondroitinase and nitrous acid degradations. The content of glycosaminoglycan in the tissue is low (0.05% dry weight) being comprised of dermatan sulphate (38%), heparin (34%), heparan sulphate (18%) and chondroitin sulphates (10%) as a percentage of total glycosaminoglycan content. Hyaluronic acid and keratan sulphate have not been detected. The composition is generally typical of a high muscle content tissue.

Carbohydrate patterns of endoscopic mucosal biopsies in cancer of the stomach and chronic gastritis

The monosaccharide composition of the soluble glycoproteins of endoscopic gastric biopsies was studied with gas-liquid chromatography in patients with carcinoma of the stomach and in patients with chronic gastritis (controls). The analyses showed (1) that monosaccharide patterns were similar in the antrum and corpus of patients with chronic gastritis, (2) that the mannose content relative to the galactose content was increased in the tumor as compared with the antrum of the same stomach (p less than 0.05) and with the antrum (p less than 0.05) and corpus (p less than 0.02) of the control stomachs, and (3) that the N-acetylgalactosamine and N-acetylglucosamine content tended to be decreased in the tumor area as compared with the antrum and corpus of control stomachs. The changes in the histologically tumor-free part of the corpus of the cancer stomachs tended to be similar in direction to those in the tumor itself.

Immunocytochemical studies of blood group A, H, I, and i antigens in gastric mucosae of infants with normal gastric histology and of patients with gastric carcinoma and chronic benign peptic ulceration

Indirect immunofluorescence studies of blood group A, H, I, and i antigens were performed on the gastric mucosae and tumor tissues of patients with gastric carcinoma, on the mucosae of patients with chronic benign gastric ulceration, and on the mucosae of infants who had died of causes other than gastrointestinal disease. The following findings were of particular interest: (1) Normal 'secretor' type mucosae were distinguishable from 'non-secretor' type mucosae by the uniform staining of the A or H antigens at the surface and in the pits. Normal 'non-secretor' type mucosae showed little staining of the H or A antigens but, instead, there was staining with anti-I(Ma) antibody. Staining with anti-I(Step) and anti-i(Den) did not show a clear correlation with the 'secretor'/'non-secretor' status of the normal mucosae. (2) Apparently normal areas of gastric mucosae of patients with gastric carcinoma or the normal part of gastric mucosae of patients with benign gastric ulcer frequently showed focal areas of loss or gain of the blood group antigens as is often seen in gastric carcinoma tissues. (3) In the mucosae of patients with intestinal metaplasia there was marked loss of A/H antigens in 'secretors' and I(Ma) antigen in 'non-secretors'. (4) Staining characteristics of tissues from gastric carcinoma were:(a) Focal loss of the expected A/H or I antigens was observed with much variation in staining from area to area, but only a minority showed complete loss of the expected staining. (b) A majority of the carcinomas from 'secretors' showed foci of substantial staining with anti-I(Ma) in contrast to normal 'secretor' mucosae. This is probably due to incomplete biosynthesis of A/H determinants. (c) Incompatible A-like staining by a rabbit anti-A serum was observed in one out of nine adenocarcinomas from blood group B or O persons. (d) A few cases showed substantial i antigen staining. The aberrant expression of blood group A, H, I, and i antigens in neoplastic as well as in some areas of morphologically normal mucosa of patients with benign and malignant diseases of the stomach is discussed in the context of current biochemical knowledge.

Gastric marker proteins. Purification and immunohistological demonstration of the chief cell esterase

An immunogenic acid stable esterase of gastric origin was purified from normal gastric juice. Specific antibodies were obtained by solid immunoadsorbents and were used for indirect immunoenzyme histology on gastric resection specimens. This esterase proved to be a cell specific marker for gastric chief cells. Different patterns of chief cell alterations in gastritis and cancer were observed.

Correlation of quantitative changes of gastric mucosal glycoproteins with aspirin-induced gastric damage in rats

Quantitative changes of gastric mucosal glycoproteins with the gastric damage induced by acetylsalicylic acid (aspirin) in rat have been studied. Gastric injury was easily observed macroscopically within one hour after the oral administration of aspirin. The most striking changes occurred at five hours, and the injury was overcome within nine hours after dosing. The glycoproteins extracted from rat stomack with Tris buffer containing Triton X-100 were fractionated on Bio-Gel A-1.5 m column chromatography and divided into three fractions. The first peak, corresponding to gastric mucus macromolecular neutral and acidic glycoproteins with or without sulphate (Fr.I), was diminished after aspirin administration. A considerable alteration of Fr.I (49% of control) appeared at three hours, and a gradual return to the control value was observed subsequently. The changes in the amount of the glycoproteins were detected before the macroscopical changes of the mucosa. These results suggest that gastric ulceration induced by aspirin may be caused by a deficiency of gastric mucus macromolecular glycoproteins of gastric mucus.

Electron-microscopic study of the villous adenoma of the colon

The author studied the electron-microscopic peculiarities of villous adenoma as illustrated by 12 cases. She found that the dominant cells of villous adenoma are undifferentiated epithelial cells. Electron-microscopic signs of malignant transformation were revealed by nuclear changes, by the changes in the cytoplasmic membrane and by the immaturity of cells. Leuchtenberger's inclusion bodies are assumed to develop by herniation of cytoplasmic processes of immature tumour cells. In one tumour associated with electrolyte loss, atypical cells were observed with an electronmicroscopic picture indicative of an intense secretory activity. However, the secretion drops differed from the normal mucus drops of the mature goblet cells of the colonic mucosa. The author believes it to be possible that the tumour cells of atypical morphological appearance secrete mucus of abnormal composition which could be responsible for the syndrome of electrolyte loss.

Purification of human intestinal goblet cell antigen (GOA), its immunohistological demonstration in the intestine and in mucus producing gastrointestinal adenocarcinomas

Goblet cell antigen (GOA) was purified from gastric signet ring cell carcinoma. It was immunogenic and was used to produced antisera which stained goblet cells of the small and large intestine and of intestinalized gastric mucosa by indirect immunological methods. Various types of gastric and colonic cancer contained GOA. These findings demonstrate a histiogenic relationship between intestinal goblet cells, various gastrointestinal cancers and associated premalignant conditions.

Carbohydrate content of endoscopic gastric biopsies in carcinoma of the stomach

An investigation of the glycoproteins of gastric mucus from biopsies of patients with gastric cancer has shown a change in certain carbohydrate components. There is a significant increase (P less than 0-001) in mannose and a significant decrease in N-acetylgalactosamine in both secretors and non-secretors from cancer-free and cancer-bearing regions of the stomach as compared with normal stomachs. The possible reasons for this change and its relation to two possible glycoprotein fractions are discussed.

Carbenoxolone: a review of its pharmacological properties and therapeutic efficacy in peptic ulcer disease

Carbenoxolone sodium has been shown to accelerate the rate of healing of both gastric and duodenal ulcers, but its overall value in duodenal ulcer is probably less because of the high rate of natural remission of duodenal ulcers. Further studies are required to decide whether it should be used prophylactically to delay ulcer recurrence. Carbenoxolone may act by affecting both the proliferative activity of gastric epithelium and the differentiation of the epithelial cells to produce mucus (as well as favourably altering the physicochemical properties of mucus and by reducing peptic activity), factors which may be relevant ot the prevention of acute gastric ulcers. Some studies suggest that carbenoxolone adds to the effect of hospitalisation and bed rest on ulcer healing. Whether bed rest confers additional benefit to the drug's ulcer healing effect in outpatients is also uncertain. There is no evidence that accelerated healing by carbenoxolone is associated with improved overall prognosis. Carbenoxolone is of greatest benefit in accelerating the healing of gastric ulcers in patients for whom hospitalisation is not possible or desirable, but it should only be used in the ambulatory patient when careful and regular observation of serum electrolytes (particularly potassium), blood pressure and weight is possible and when it is known that the patient will attend regular follow-up. Patient must be educated in the proper use of the drug. If severe mineralocorticoid-like toxic effects such as sodium and water retention and hypokalaemia appear, as they do in a variable proportion of patients but most frequently in those receiving excessive doses, carbenoxolone should be stopped and the complication treated; they respond to thiazide diuretics and potassium supplements, and probably to amiloride given in conjunction with a low dose of a thiazide diuretic. Treatment with carbenoxolone can continue with concurrent diuretic therapy in patients with less severe side-effects. Optimum therapeutic effect in gastric ulcer with the least side-effects is achieved with a dosage of 100mg carbenoxolone tablets 3 times daily for the first week followed by 50mg 3 times daily thereafter, best taken before meals. A lower dosage is desirable in the elderly and in those with liver, cardiac or renal disease. Barium meal or preferably endoscopic examinations should be performed regularly and therapy continued until the ulcer is healed. Dosage for duodenal ulcer is 50mg 4 times daily, in special positioned-release capsules. These are best taken about 20 minutes before meals.

[Isolation and composition of a glycoprotein from lamb gastric mucosa]

A glycoprotein is isolated from lamb gastric mucosa. It is purified first by reduction with dithiothreitol and then by chromatography on CM-Sephadex followed by gelfiltration on Sephadex G-75. Its homogeneity is investigated by disc electrophoresis, immunoelectrophoresis, analytical ultracentrifugation and identification of the carboxy- and amino-terminal amino acids. This glycoprotein contains 56 p. cent carbohydrates, consisting of N-glycolyneuraminic acid, fucose, galactose, and hexosamines. Hexosamines and galactose are in equimolar ratio ; galactosamine and glucosamine in the ratio 1 :2. The amino acid composition shows that threonine, serine and proline account for half of the amino acid residues. The cysteine origin and function are discussed.