The carbohydrate components of hydrolysates of gastric secretion and extracts from mucous glands of the gastric body mucosa and antrum

Isolation and characterization of a collagen-binding glycoprotein from chondrocyte membranes

A collagen-binding glycoprotein was isolated from purified chick chondrocyte surface membranes by affinity chromatography on type II collagen-Sepharose. The purified glycoprotein has an apparent mol. wt. of 31,000 and binds to native chick collagen types I, II, III, V and M. Although it contains 30% carbohydrates, the majority of which is fucose, it is hydrophobic and soluble only in detergents. The integral membrane protein character of the 31-K protein became apparent from its ability to insert into lecithin vesicles. Liposome-inserted 31-K protein binds 125I-labelled type II collagen in the presence of 0.5 M NaCl, while detergent-solubilized 31-K protein is dissociated from type II collagen by 0.05-0.1 M NaCl. Electron microscopic studies employing the rotary shadowing technique indicate that 31-K protein particles bind to the ends of collagen molecules. We propose that this glycoprotein serves as anchorage site for extracellular collagen to the chondrocyte membrane and thus may be involved in cell-matrix interactions in cartilage.

Radiolysis of human gastric glycopolypeptides in aqueous solution

The degradation of human gastric glycopolypeptides by hydroxyl radicals formed in irradiated N2O-saturated aqueous solution has been investigated. Gel exclusion chromatography shows the formation of lower molecular weight degradation products after irradiation and the appearance of unsaturated carbonyl-containing products which absorb in the ultra-violet. The radiation-induced destruction of individual monosaccharides in three human glycopolypeptides having different oligosaccharide chains has been measured. The results indicate that the structure of the oligosaccharide chain determines the extent of destruction of each type of monosaccharide present.

The metabolism and structure of phosphoglycoproteins in rat brain

Glycoproteins that contain phosphohexosyl groups were found to be present in the myelin- and synaptosomal-enriched fractions as well as in the microsomes of rat brain. The kinetics of flow of intraperitoneally injected [32P]phosphate suggests that the phosphate is enzymatically added in structures found in the microsomal fraction. The newly synthesized phosphoglycoproteins then appear in the soluble fraction of the synaptosomes and in the cytosol, prior to incorporation into the membranes of the synaptosomes and myelin. Phosphoglycopeptides recovered from the phosphoglycoprotein contain 3 Mannose units per N-acetylglucosamine residue; one of the mannose residues is phosphorylated. [13C]NMR studies indicate that the phosphoglycopeptides contain a chitobiose group and more than four sugar residues. Thus, the phosphomannoglycopeptides from rat brain contain an average of 2 N-acetylglucosamine, 6 mannose, and two phosphate moieties per oligosaccharide chain. Enzymatic treatment with alpha-mannosidase failed to remove the phosphomannose, although some mannose residues were released. Thus, the phosphorylated mannose is not removed by the glycosidase and terminal nonphosphorylated mannose residues are present in the oligosaccharide. The phosphate residues are removed by treatment with alkaline phosphatase.

Glycoprotein synthesis in the mucous cells of the vascularly perfused rat stomach. III. Mucous cells of the antrum and the duodenal glands

Labeled leucine, serine, galactose, glucosamine, fucose, and sulfate were administered to rat stomachs in a vascular perfusion system. Sections of gastric fundus and antrum, and of the duodenal glands, were studied by light-microscopic autoradiography. The rate of incorporation of radioactive label in the various mucous cell types of the antrum and of the duodenal glands was measured by counting the silver grains over each cell type and comparing this rate with that of the surface mucous cells of the fundus. The following major observations were made: The patterns of incorporation in the mucous cells on the surface and in the pits of the antrum did not differ essentially from those of the surface mucous cells of the fundus. On the contrary, the incorporation patterns of the surface mucous cells of the fundus differed considerably from those of the mucous cells of the antral glands and from the mucous cells of the duodenal glands. The mucous cells of the antral glands showed a lower incorporation rate of amino acids and of (amino) sugars, especially of galactose and glucosamine, but a higher incorporation rate of sulfate. The mucous cells of the duodenal glands showed a considerably higher rate of incorporation for serine, but a lower rate for glucosamine. No differences were seen for leucine, galactose, and sulfate. The relatively low synthetic activity of the mucous cells of antral glands correlates well with the various amounts of RER, Golgi system, and secretory granules, found in these cells, and with the histochemical staining characteristics of their mucous granules. The mucous cells of the duodenal glands are characterized by typical parallel arrays of their numerous RER cisternae and by a low number of small secretory granules.

The assessment of mucus substances in gastric juice from duodenal ulcer patients and normal subjects

The carbohydrate and nitrogen content of the gastric juice was assessed in 18 persons whose diagnosis were unknown to the investigators and the data compared by discriminant function analysis with similar measurements from 42 patients with proven duodenal ulceration and 22 normal controls. It was possible to assess correctly 14 of the 18 patients (77.8%) of the unknown group as having a duodenal ulcer. The results of three patients (16.7%) were equivocal, and one person (5.5%) was wrongly classified. The investigation confirms that the carbohydrate and nitrogen content of gastric secretion in duodenal ulcer patients is abnormal.

Retrospective histochemical study of mucosubstances in adenocarcinomas of the gastrointestinal tract

Use of the PATS/KOH/PAS and PB/KOH/PAS techniques and the diamine method (Spicer 1965) together with the demonstration of metachromasia with toluidine blue pH 3.0, for the study of carbohydrates in a retrospective study of gastric and colorectal adenocarcinomas, disclosed an increase in the sulphate content and the absence of O-acylated sialomucins in the majority of gastric adenocarcinomas. In the colorectal tumours there is no change in the degree of sulphation normally present in this area, but the degree of acylation of the sialic acid in adenocarcinoma is very different to that of normal mucosa and appears related to the degree of differentiation of the tumour. The mucosa adjacent to tumours from both areas were also studied, as well as gastric intestinal metaplasia.

Comparative histochemistry of gastrointestinal mucosubstances

Two histochemical sequential staining techniques, Alcian blue-PAS (AB-PAS) and high-iron-diamine-Alcian blue (HID-AB), which differentiate neutral from sulfated and non-sulfated acid mucosubstances, were applied to sections from the gastrointestinal tract of eleven mammalian species, including man, to study patterns of distribution of gastrointestinal epithelial mucosubstances. The application of these techniques under uniform laboratory conditions enabled a detailed description of epithelial mucosubstances throughout the gastrointestinal tract relative to location in each species as well as a comparison of their distribution among various species. The results showed that all of the 11 species studied had a distinctly different distribution of epithelial mucosubstances throughout the entire gastrointestinal tract. These differences were most obvious in the stomach and duodenum. In each species, neutral mucosubstances were most evident in the stomach and acid mucosubstances in the intestines, with sulfomucins most prominent in the large bowel. Acid mucosubstances were noted in Paneth cell granules of rodent species only. These histochemical observations make available a uniform comparative basis for the normal distribution of mammalian gastrointestinal mucosubstances which should facilitate their study in diverse pathological conditions.

The effect of mucin on the bioavailability of tetracycline from the gastrointestinal tract; in vivo, in vitro correlations

The bioavailability of tetracycline in the presence and absence of a porcine gastric mucin dispersion (1% W/V) has been studied by in vivo perfusion of the rat small intestine, the rat everted gut, a diffusion cell technique and the Sartorius Absorption Simulator Apparatus. In the presence of the mucin preparation an approximate 50% reduction in the numerical values of each of the parameters used to measure the tetracycline movement across the membrane was found. The physiological significance of each technique and the methods themselves are discussed. Interaction of tetracycline with the porcine gastric mucin preparation is considered in relation to the molecular structure of mucus. The results suggest the drug is bound in some way, as yet undefined, to the mucin macromolecule.

Properties of an antigenic polysaccharide from Corynebacterium parvum

Corynebacterium parvum strain 10390 is an antitumor agent and stimulant of the reticuloendothelial system and produces a soluble antigen towards the end of its growth cycle. This material, which is a cell wall component and can also be released from the organism by acid or alkaline hydrolysis, has been purified. It is an acidic polysaccharide of molecular weight 100,000 to 150,000 and contains galactose, glucose, fucose, N-acetylgalactosamine, N-acetylglucosamine, uronic acids, sialic acids, and a small proportion of amino acids. The antigen gives a precipitin reaction with antisera raised against the whole organism and also binds to animal cells. The antigenic determinants are extremely resistant to oxidation, reduction, and enzymatic and chemical hydrolysis, but the single cell-binding site is destroyed by alkali and also by Helix pomatia digestive juice, alginase, and neuraminidase without substantially affecting the molecular weight. This site is inaccessible until the molecule is released from the cell surface. The possibility that the soluble antigen is the biologically active fraction of C. parvum is discussed.

An assessment of methanolysis and other factors used in the analysis of carbohydrate-containing materials

The stability of monosaccharides in methanolic hydrochloric acid of different strengths and at different temperatures was determined. They are generally stable for 24h in methanolic 1m- and 2m-hydrochloric acid at both 85 degrees C and 100 degrees C, but undergo considerable destruction in methanolic 4m- and 6m-hydrochloric acid at 100 degrees C. Analysis of glycopeptides and oligosaccharides of known composition showed that release of carbohydrate was complete within 3h in methanolic 1m-hydrochloric acid at 85 degrees C. Removal of methanolic hydrochloric acid by rotary evaporation resulted in considerable losses of monosaccharides, which could be prevented by prior neutralization. Methanolysis caused extensive de-N-acetylation of acetamidohexoses, so that a re-N-acetylation step is necessary in the analytical procedure. The addition of acetic anhydride for this purpose also prevented loss of internal standard by adsorption on the insoluble silver salts used in neutralization. Several trimethylsilylating agents were studied and suitable conditions are recommended. The effects on the analytical system of water and some common organic and inorganic contaminants are assessed.

The interaction of concanavalin A with blood-group-substance glycoproteins from human secretions

1. Gastric juice, saliva and ovarian-cyst fluid were fractionated into glycoprotein components by centrifuging to equilibrium in a caesium chloride density gradient. 2. The glycoprotein fractions from the gastric juice of two group O non-secretors, two group O secretors and three group A secretors all formed insoluble complexes with concanavalin A. 3. Fractions showing maximum interaction with concanavalin A had maximum blood-group activity measured by the haemagglutination-inhibition technique. The sulphate content of the gastric glycoproteins was unrelated to the capacity to interact with concanavalin A. 4. No interaction was found between concanavalin A and the glycoprotein fractions from any of the saliva or ovarian-cyst-fluid samples tested, implying that there is a structural difference in blood-group-substance glycoproteins in gastric juice when compared with those in saliva and ovarian-cyst fluid. 5. The protein components of each of the secretions tested, gastric juice, saliva and ovarian-cyst fluid, interacted with concanavalin A.