Gastric mucus: Isolation and polymeric structure of the undegraded glycoprotein: Its breakdown by pepsin

Pearson, Jeffrey P.; Allen, Adrian; Venables, C W

doi:10.1016/0016-5085(80)90672-1

Cited by 118 publications

(41 citation statements)

References 16 publications

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“…The starting density of the gradient was 1.42 g/ml, and after centrifugation and fractionation the densities of the fractions ranged from 1.35 g/ml to 1.54 g/ml (fig 2). Cellular proteins band with a buoyant density of between 1.29 and 1.37 g/ml 36. The mucin was identified by the PAS reaction,35 and was in fractions 4 to 7.…”

Section: Resultsmentioning

confidence: 99%

The human trefoil peptide, TFF1, is present in different molecular forms that are intimately associated with mucus in normal stomach

Newton

Allen²,

Westley³

et al. 2000

Gut

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Background-TFF1 is a 6.5 kDa secreted protein that is expressed predominantly in normal gastric mucosa. It is coexpressed with mucins and it can form dimers via a free carboxy terminal cysteine residue. Aims-To investigate the molecular forms of TFF1 that are present in normal human stomach and the association of the diVerent molecular forms with mucus. Subjects-All subjects had macroscopically normal stomachs at gastroscopy. None had a significant past medical history. Methods-TFF1 was detected in normal gastric mucosa and adherent mucus by western transfer analysis after electrophoresis on reducing and non-reducing polyacrylamide gels. In some instances, proteins were fractionated by caesium chloride density gradient centrifugation prior to detection of TFF1. The location of TFF1 in gastric mucosa with an intact adherent mucus layer was assessed by immunohistochemistry. Results-Three diVerent molecular forms of TFF1 were detected: TFF1 monomer, TFF1 dimer, and a TFF1 complex with an apparent molecular mass of about 25 kDa. TFF1 was present at higher concentrations than realised previously. The TFF1 complex was present in the adherent mucus gel layer but while its interaction with mucin was destabilised by caesium chloride, the interaction between mucin and the TFF1 dimer was resistant to caesium chloride. Conclusions-Most of TFF1 in normal human gastric mucosa is present in a complex that is stabilised by a disulphide bond. TFF1 is intimately associated with mucus. The high concentration, colocalisation, and binding of TFF1 to gastric mucus strongly implicate TFF1 in gastric mucus function. (Gut 2000;46:312-320)

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Section: Resultsmentioning

confidence: 99%

The human trefoil peptide, TFF1, is present in different molecular forms that are intimately associated with mucus in normal stomach

Newton

Allen²,

Westley³

et al. 2000

Gut

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“…These glass wool plugs and mucus gel were homogenised in 1/15 M, pH 6.5 phosphate buffer, with a cocktail of protease inhibitors (1 mM iodoacetamide, 100 mM aminocaproic acid, 5 mM benzamidine hydrochloride, 10 mM EDTA, 10 mM N-ethylmaleimide, and 1 mM phenyl methyl sulphonyl fluoride) 17. The mucin in the supernatant was fractionated using equilibrium density gradient centrifugation in caesium chloride (starting density 1.42 g/ml) 18. The resultant density gradient was separated into nine equal fractions and assayed for glycoprotein using the PAS reaction 19.…”

Section: Methodsmentioning

confidence: 99%

“…Samples were then each fractionated separately in a caesium chloride density gradient 18. Subsequently mucin rich fractions from the biopsy specimens and brushings with density 1.41–1.5 g/ml were separately pooled, dialysed exhaustively against distilled water, and then freeze dried.…”

Section: Methodsmentioning

confidence: 99%

Helicobacter pylori in vivo causes structural changes in the adherent gastric mucus layer but barrier thickness is not compromised

Jordan

Oliver

et al. 1998

Gut

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Background-It has been proposed that a pathogenic eVect of Helicobacter pylori is a weakening of the protective mucus barrier; however, this remains controversial. Aims-To clarify the eVects of H pylori infection on the mucus gel barrier in vivo.Methods-Mucus gel polymeric structure and the thickness of the adherent mucus barrier were measured in endoscopic biopsy samples in subjects with and without H pylori infection. Results-There was a significant 18% reduction in the proportion of polymeric gel forming mucin in the adherent mucus layer in H pylori positive compared with negative subjects. There was no change in the adherent mucus thickness between H pylori positive and negative subjects without gastric atrophy (mean (SD): 104 (26) µm, 106 (30) µm respectively). There was however a significant reduction in mucus thickness in those H pylori positive subjects with underlying gastric atrophy (84 (13) µm, p=0.03) compared with those without atrophy. Conclusions-A partial breakdown in gel forming structure of the gastric mucus barrier does occur in H pylori infection per se but this is insuYcient to cause a collapse of the mucus barrier. (Gut 1998;43:470-475) Keywords: Helicobacter pylori; gastric mucus Helicobacter pylori infection leads to gastritis and is an aetiological factor in the pathogenesis of peptic ulceration.1 H pylori is located within the adherent mucus barrier, particularly in the region of the gastric pit, close to the mucosal surface.2 The mucus barrier, together with epithelial bicarbonate secretion, is considered to be the first line of mucosal defence against acid and pepsin.3 This mucus layer also provides a protective environment for H pylori to colonise. 4 However, it is controversial whether or not H pylori colonisation results in changes in mucus structure and production, thereby impairing its protective eYcacy.A weakening of the mucus barrier by H pylori, leading in some cases to its collapse, has been proposed, based on the demonstration in vitro of a mucolytic proteinase in filtrates from cultures of H pylori.5 6 However, other groups have failed to show significant amounts of proteinase activity in either culture filtrates or extracts of H pylori.7-9 A non-proteolytic, urea dependent breakdown of the mucus gel by filtrates of H pylori has been observed and explained by urease activity producing ammonium ions which disrupted mucus lipid interactions.8 A study in vivo looking at mucus gel in gastric washouts, but not from the adherent mucus gel barrier, showed that mucus viscosity from H pylori infected subjects was not reduced compared with that from noninfected subjects.10 One study in vivo, observing unfixed sections of gastric mucosal biopsy specimens, showed an up to 50% reduction in mean mucus thickness of the adherent mucus gel barrier in patients with H pylori infection, compared with non-infected controls.11 Recently decreased expression of MUC5AC and aberrant expression of the glandular mucin MUC6 in gastric epithelial cells has been shown to occur with H pylori in...

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“…Pronase, a kind of protease, is known to cause both extensive degradation of mucins and a reduction in mucus viscosity [18]. To our knowledge, while an in vitro biochemical effect of pronase on the gastric mucus has been reported [19], histochemical evidence of an in vivo effect of pronase on the SMGL has not been obtained. Oral administration of pronase is thought to remove the gastric mucus, and therefore pronase is usually used as a premedication for endoscopy in Japan [20].…”

mentioning

confidence: 99%

Additive Effect of Pronase on the Efficacy of Eradication Therapy Against Helicobacter pylori

et al. 2002

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Gastric mucus: Isolation and polymeric structure of the undegraded glycoprotein: Its breakdown by pepsin

Cited by 118 publications

References 16 publications

The human trefoil peptide, TFF1, is present in different molecular forms that are intimately associated with mucus in normal stomach

The human trefoil peptide, TFF1, is present in different molecular forms that are intimately associated with mucus in normal stomach

Helicobacter pylori in vivo causes structural changes in the adherent gastric mucus layer but barrier thickness is not compromised

Additive Effect of Pronase on the Efficacy of Eradication Therapy Against Helicobacter pylori

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