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Query: UMLS:C0149514 (bronchitis)
 6,902 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The physical and chemical properties of bronchial epithelial mucus depend on its special mix of macromolecules and lipid constituents: these are different in the normal airway under baseline conditions from one stimulated acutely, and show major modification in disease. Since the last conference, density gradient ultracentrifugation has been extended to the study of normal bronchial mucus in addition to that of sputum from patients with chronic bronchitis, cystic fibrosis and asthma, and has revealed striking differences between the chemical profiles of normal and hypersecretory mucus. Normal mucus represented individual bronchial aspirates, obtained at fiberoptic bronchoscopy from healthy human volunteers (non-smokers), aspirates from normal dogs (before SO2 exposure in a canine model of SO2 induced bronchitis) and secretions released in vitro by human bronchial and canine tracheal explants. Mucus 'in transition' included aspirates from otherwise healthy smokers and from dogs early in irritation. Hypersecretory mucus included, besides those mentioned above, aspirates from dogs that had developed bronchitis and the excessive mucus produced by some patients with acute quadriplegia. Lipids. In normal mucus, human (unpooled) and canine, neutral lipids are the predominant species, with lesser amount of phospholipids: no glycolipids are detected. The first qualitative change on irritation, even before macromolecular yield increases, is appearance of glycolipids. In hypersecretory mucus, human (including quadriplegics) or canine, glycolipids are detected in appreciable amounts and often are the predominant species: they include complex forms such as sialic acid containing gangliosides. Organ and cell culture studies establish that these lipids are produced by airway epithelial cells. These lipids are important to gel formation. Glycoconjugates. A major recent advance is the recognition that normal mucus does not contain typical epithelial glycoprotein. Its glycoconjugate is of higher density with sugars typical of both glycoprotein (GP) and proteoglycan (PG) and with an amino acid profile more akin to PG (glycine greater than serine greater than threonine). In transition to hypersecretion, a 'mixed molecule' changes its sugar mix to produce a density typical of GP. In hypersecretion, the epithelial GP develops a typical buoyant density and amino acid profile (threonine greater than serine greater than glycine). Organ culture of bronchial explants, and more recently cell culture, establish that the PGs are major products of airway secretory cells. The normal airway is capable of producing glycoprotein on cholinergic stimulation. The range of glycoconjugates present in the secretion support the wide range of granule and cell features identified in vivo. Monoclonal antibody raised to a pure preparation of bronchial epithelial glycoprotein reacts with mucous cells in the surface epithelium and also in the submucosal gland in both human and canine airways.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Macromolecular and lipid constituents of bronchial epithelial mucus. 270 77

Density-gradient analysis was used to follow the transition from normal to hypersecretory bronchial mucus in a model of bronchitis induced in dogs by chronic exposure to SO2 gas. Aspirates of saline bronchial lavage were obtained by fiberoptic bronchoscopy from dogs before, during a 6- to 9-month exposure period to SO2 gas, and during a recovery period of similar duration. Prior to SO2 exposure, aspirates from all animals had a low yield of nondialyzable macromolecules (15 +/- 6 mg/aspirate) and similar composition. Specifically, epithelial glycoprotein of typical buoyant density was not detected; rather a glycoconjugate of higher buoyant density with features of both proteoglycan and glycoprotein was identified. Neutral lipids were predominant with lesser amounts of phospholipids; no glycolipids were detected. During the SO2 exposure period, aspirates from five of the eight dogs contained components similar in buoyant density to human bronchitic glycoprotein. Glycoprotein isolated from the canine aspirates was similar to glycoprotein isolated from human chronic bronchitic sputum, having the same carbohydrate composition and range of oligosaccharide size. Further, during and after SO2 exposure some aspirates contained appreciable amounts of glycolipids. These data demonstrate substantial similarities in composition between normal human and canine mucus and in mucus isolated from dogs with chronic airway inflammation induced by repeated irritant exposure and from human patients with chronic bronchitis.
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PMID:Transition from normal to hypersecretory bronchial mucus in a canine model of bronchitis: changes in yield and composition. 334 78