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At least 19 recordsLinked to original sources
PubMed1979

Hydrophobic interaction of fluorescent probes with fetuin, ovine submaxillary mucin, and canine tracheal mucins.

The presence of hydrophobic sites in fetuin, ovine submaxillary mucin and two homogeneous canine tracheal mucins was established by fluorescence probe techniques. The interaction between the above-mentioned glycoproteins and two hydrophobic fluorescent compounds, sodium mansate and mansylphenylalanine, was accompanied by an enhancement in fluorescence and a shift of the fluorescence maxima to shorter wavelengths. The introduction of a phenylalanine residue to the mansyl group enhanced the binding affinity of the probe for the hydrophobic sites of these glycoproteins as evidenced by lower values for the dissociation constants. The high molecular weight (581 600) tracheal mucin, which had the highest carbohydrate content (80%) of all the glycoproteins investigated, exhibited the highest fluorescence enhancement and the largest number of binding sites for these fluorescent probes.

Animals↗
PubMed1975

A histochemical method of differentiating lower gastrointestinal tract mucin from other mucins in primary or metastatic tumours.

Epithelial mucins of the normal terminal ileum, caecum, colon, and rectum of man are unique in that they alone exhibit staining following the periodate-borohydride/KOH/PAS technique. Application of this technique enables one to differentiate those mucin-producting metastases arising from adenocarcinoma of the lower gastrointestinal tract from those arising elsewhere, and may occasionally be useful in determining the site of the primary tumour when it is in doubt. Furthermore, it was found to be especially useful in distinguishing between primary adenocarcinoma of the lung and metastases in the lung from adenocarcinoma of the lower gastrointestinal tract.

Adenocarcinoma↗
PubMed1979

The role of disulphide bonds in human intestinal mucin.

Goblet-cell mucin (mucin 1) was isolated and purified from human small-intestinal scrapings. After application of mucin 1 to DEAE-Bio-Gel (A) columns, most of the glycoprotein (76-94% of hexoses) was eluted in the first peak (designated mucin 2). Minor amounts of acidic glycoproteins were eluted with 0.2m- and 0.4m-NaCl in later peaks. Analyses of mucin 1 and mucin 2 revealed mucin 2 to be a monodisperse highly glycosylated glycoprotein containing 6.3% by wt. of protein, N-acetylgalactosamine, N-acetylglucosamine, galactose and fucose. Mucin 1 was similar in composition, but was polydisperse and contained more protein (12.3% by wt.) as well as N-acetylneuraminic acid. Analytical CsCl-gradient ultracentrifugation showed both mucin 1 and mucin 2 to have a major component with an average buoyant density of 1.47000g/ml. Mucin 1 also contained a slightly less-dense minor glycoprotein component. After exhaustive reduction and alkylation mucin 1 retained its major component, but partly dissociated into two lighter glycoprotein components. Mucin 2, in contrast, did not change its density distribution after reduction. Band ultracentrifugation in (2)H(2)O-containing iso-osmotic buffers showed that mucin 1 contained a major fast-sedimenting component (s(o)=37+/-2S), and a minor amount of a slower-sedimenting component. After reduction there was an increased quantity of the latter component, for which an s(o) value of 14.5S was calculated. In contrast, mucin 2 was unaltered by reduction (s(o)=33+/-2S). These findings indicate that the major component of goblet-cell mucin (mucin 2) does not dissociate after S-S-bond reduction, and thus does not apparently rely for its polymeric structure on the association of subunits through covalent disulphide bonds. However, the effects of reduction on mucin 1 suggest that in the native mucin intramolecular disulphide bonds in the minor glycoproteins may stabilize their structure, permitting secondary non-covalent interactions to develop with the major dense mucin (mucin 2) protein.

Amino Acids↗
PubMed2026

A Quantitative Lung Mucin Score to Identify Chronic Bronchitis.

BACKGROUND: We previously demonstrated that sputum total mucin concentration is an objective marker for chronic bronchitis (CB). This current study introduces a novel Mucin Quantitative Score (MUCQ) that combines total mucin concentration and mucin composition to improve the assessment of risk, onset of clinically diagnosed disease, and progression of muco-obstructive lung diseases. METHODS: Patients from the SPIROMICS (SubPopulations and InteRmediate Outcome Measures in COPD Study) cohort were classified as having CB, or not, based on clinical questionnaires. Using the measured total mucin, MUC5AC, and MUC5B concentrations in sputum samples, we calculated MUCQ as [Total mucin]×([MUC5AC]÷[MUC5B])÷100 μg/ml, which is a unitless, weighted concentration score. Our primary outcome was the net reclassification of patients with a diagnosis of CB, or not, based on total mucin concentrations in their sputum compared with using the MUCQ score. Participants were first classified as CB- positive or -negative using a total mucin concentration threshold of 2306 μg/ml, then reclassified using the MUCQ threshold of 4.30. Associated z statistics and a P value for the primary outcome are reported. RESULTS: Among 164 patients in the SPIROMICS cohort with clinically defined CB, using the MUCQ score up-classified 18 patients who were currently smoking to a diagnosis of CB and down-classified 5 patients who were currently smoking and 3 control participants who had never smoked, compared with the classification of CB was based on total mucin concentrations alone (P=0.001). In addition, MUCQ correlated with other clinical and pathological indices of chronic airway disease and airway obstruction. CONCLUSIONS: The MUCQ metric was superior in distinguishing patients with CB compared to a total mucin concentration. Trials are needed to ascertain the prospective use of MUCQ metrics in research and clinical settings for assessment, management, and tracking therapeutic responses in CB and potentially other muco-obstructive conditions. (Funded by the National Institutes of Health and others.).

Humans↗
PubMed1978

Enhancement of the viscosity of mucin by serum albumin.

The interaction of serum albumin with a model epithelial mucin from pig stomach was explored by rotary viscometry. During 30 min of incubation of human serum albumin(20mg/ml) and pig gastric mucin (8mg/ml) in iso-osmotic buffers at 37 degrees C, the solution became markedly viscous. Viscosity enhancement was proportional to albumin concentration (2-40mg/ml), was most pronounced under conditions of low shear rate (less than 45S-1), and was considerably greater than the additive or multiplicative viscosity values calculated from albumin or mucin solutions measured separately. The viscous mucin-albumin complex was destroyed by high shear rates (greater than 90S-1), but slowly re-formed under zero shear conditions. Elevation of pH (7 to 9), ionic strength (0.1 to 1.0), and addition of disodium EDTA (5mM) did not cause marked or specific alterations in the viscosity of the mixture, suggesting that electrostatic interactions probably do not stabilize mucin-albumin complexes. Urea (7M) and heating (35 to 55 degrees C) caused a major increase in the viscosity of mucin and mucin-albumin mixtures, suggesting that rupture of hydrogen bonds, unfolding and partial denaturation of mucin promotes greater intertangling (possibly hydrophobic interactions) between mucin and albumin molecules. The implications of mucin-albumin interaction in diseases associated with mucus obstruction are briefly discussed.

Animals↗
PubMed1978

Selective binding of blood group-reactive salivary mucins by Streptococcus mutans and other oral organisms.

Strains of Streptococcus mutans of four genetic groups and five serotypes, and strains of S. sanguis, S. mitis, S. salivarius, Actinomyces naeslundii, and A. viscosus, were found to bind blood group-reactive (BGR) mucin isolated from whole human saliva. The bacteria studied bound mucins with blood type A or B reactivity to a similar extent, suggesting that the carbohydrate moieties responsible for the A and B antigenic determinants were not involved. The organisms studied appeared to bind different fractions of BGR mucin molecules because preparations absorbed with cells of a given oral species no longer contained BGR molecules which bound to homologous organisms but still possessed BGR components which bound to varying degrees to other bacteria. Differences were even noted among S. mutans strains belonging to different genetic groups and serological types. Immunoglobulins could not be detected in the mucin preparations, and addition of anti-human immunoglobulin A (IgA), IgG, or IgM serum to reaction mixtures did not affect binding. Mucin pretreated with periodate or iodoacetate no longer bound to S. mutans H12 cells, suggesting that carbohydrate moieties and sulfhydryl groups played an essential role. Active cell metabolism was not required for BGR mucin binding; however, pretreatment of H12 cells with periodate or heat (100 degrees C for 15 min) reduced binding. Mucin labeled with [(14)C]phenyl isothiocyanate appeared to bind to S. mutans H12 cells comparably to untreated mucin; the binding also appeared to be specific because less than 15% of the labeled material became bound when incubated with an excess of streptococci. Binding of [(14)C]phenyl isothiocyanate-labeled mucin was not affected by neutral sugars tested or by preparations of c antigen, glycerol teichoic acid, dextran, or crude glucosyltransferase. However, binding was inhibited by several amines. BGR salivary mucins are present in the acquired pellicle covering teeth; the ability of bacteria to selectively bind such components suggest that they may serve as receptor molecules involved in the attachment of bacteria to teeth.

Actinomyces↗
PubMed2022

Cystic Fibrosis Airway Mucus Hyperconcentration Produces a Vicious Cycle of Mucin, Pathogen, and Inflammatory Interactions that Promotes Disease Persistence.

The dynamics describing the vicious cycle characteristic of cystic fibrosis (CF) lung disease, initiated by stagnant mucus and perpetuated by infection and inflammation, remain unclear. Here we determine the effect of the CF airway milieu, with persistent mucoobstruction, resident pathogens, and inflammation, on the mucin quantity and quality that govern lung disease pathogenesis and progression. The concentrations of MUC5AC and MUC5B were measured and characterized in sputum samples from subjects with CF (N = 44) and healthy subjects (N = 29) with respect to their macromolecular properties, degree of proteolysis, and glycomics diversity. These parameters were related to quantitative microbiome and clinical data. MUC5AC and MUC5B concentrations were elevated, 30- and 8-fold, respectively, in CF as compared with control sputum. Mucin parameters did not correlate with hypertonic saline, inhaled corticosteroids, or antibiotics use. No differences in mucin parameters were detected at baseline versus during exacerbations. Mucin concentrations significantly correlated with the age and sputum human neutrophil elastase activity. Although significantly more proteolytic cleavages were detected in CF mucins, their macromolecular properties (e.g., size and molecular weight) were not significantly different than control mucins, likely reflecting the role of S-S bonds in maintaining multimeric structures. No evidence of giant mucin macromolecule reflecting oxidative stress-induced cross-linking was found. Mucin glycomic analysis revealed significantly more sialylated glycans in CF, and the total abundance of nonsulfated O-glycans correlated with the relative abundance of pathogens. Collectively, the interaction of mucins, pathogens, epithelium, and inflammatory cells promotes proteomic and glycomic changes that reflect a persistent mucoobstructive, infectious, and inflammatory state.

Cystic Fibrosis↗
PubMed1979

Radioimmunoassay of human intestinal goblet cell mucin. Investigation of mucus from different organs and species.

We have developed a double-antibody radioimmunoassay for the quantitative measurement of human goblet cell mucin (GCM) in order to study intestinal mucus in human and other species. The assay used 3H-labeled mucin as the antigen, rabbit antisera, and sheep anti-rabbit IgG antisera as the second antibody. A number of applications of the assay were investigated. A survey of human tissues revealed that mucins of the rectum, colon, and small intestine had identical affinity for the rabbit antibody, whereas lung eyelid conjunctiva, esophagus, and stomach reacted less strongly. GCM concentration ranged from 1.9 to 14 microgram mucin protein/mg tissue protein in the small and large intestine, respectively. The radioimmunoassay was also found to be useful as a marker during the isolation of GCM from human ileal extracts, where it indicated that a 10,000-fold purification had been achieved. Antigenic determinants of the mucin did not rely upon ABH blood group-specific terminal sugars in oligosaccharide chains. A comparison of mucins among various species revealed a partial species specificity of the GCM antibody. Human GCM cross-reacted with dog, monkey, and rabbit mucins, but not with mucins of rat, pig, toad, and oyster. Organ distributions of cross-reactive mucins in rabbit tissues indicated a pattern that was qualitatively similar to that seen in human tissues. Possible implications of these findings for autoimmune diseases are briefly discussed.

Animals↗
PubMed1978

The roles of mediators, irritants and allergens in causing mucin secretion from the trachea.

Two species, the cat and the goose, have been investigated to determine whether a variety of pharmacological mediators, irritants and allergens change the rate at which mucins (mucus glycoproteins) are secreted into the trachea. Mucins were labelled by the administration of radioactive precursors which the mucous cells took up and incorporated into glycoproteins. These were periodically washed out of a segment of trachea with physiological saline solution. Changes in the amount of mucin secreted were estimated from measurements of the amount of bound radioactivity in tracheal washings. Histamine increased mucin secretion but the effects were stronger and more consistent in the goose than in the cat. A variety of prostaglandins increased the secretion in both species. 5-Hydroxytryptamine failed to stimulate mucin output in the cat. Ammonia and cigarette smoke both increased mucin secretion in the cat and preliminary results suggest that this was by a combination of local and reflex mechanisms. O-Chlorobenzilidine malononitrile increased secretion from the goose trachea entirely by a local mechanism. Preliminary experiments in which sensitized cats were challenged by various routes have equivocal results on whether anaphylaxis increases airway mucin secretion. It is concluded that irritants cause mucin secretion both by reflexes and local mechanisms. The mechanisms for the latter may well include release of pharmacological mediators.

Allergens↗
PubMed1975

Calcium binding to intestinal goblet cell mucin.

1. Binding of Ca-2+ to goblet cell mucin of rat small intestine was studied using equilibrium dialysis against 0.01 M Tris/HCl buffer (pH 7.4) and tracer amounts of 45-CaCl2. Binding was found to reach saturation at a Ca free -2+ concentration of 0.1--1.0 mM, to be independent of temperature (4-37 degrees C), and to increase with increasing pH (5.0-8.7). At low concentrations of Ca free -2+ (smaller than 0.03 mM) the binding curve was sigmoidal, suggesting positive cooperativity of binding sites and a possible change in the tertiary structure of the mucin. Binding was markedly reduced, and sigmoidicity abolished, by removal of sialic acid from the mucin, or by adding 0.14 M NaCl to the dialysis medium. This latter finding suggests that, in vivo, other cations would compete for Ca-2+ binding ligands. 2. Under conditions mimicking those used for binding studies, CaCl2 (10- minus 5 M) was found to cause a small increase (0.03 units) in the absorbance of mucin solutions, especially in the ultraviolet region, possibly indicating increased light scattering. No change in the solubility of the mucin was observed after the addition of CaCl2 (10- minus 6-10- minus 4 M). A significant decrease in viscosity of the mucin was noted, however, with the addition of CaCl2 (10- minus 6-10- minus 2 M). Together with the binding data, these findings suggested that during binding, Ca-2+ combines with negative charges on goblet cell mucin (especially those of sialic acid carboxyl groups) and induces contraction or folding of the macromolecule which promotes cooperative cation binding. No evidence was obtained to suggest that CaCl2 caused precipitation, polymerization or gelation of the mucin in 0.01 M Tris/HCl.?

Animals↗
PubMed1979

Histochemistry of mucins in the submaxillary salivary gland of buffalo (Bubalus bubalis).

The histochemistry of mucins in the submaxillary salivary gland has been studied in 10 buffaloes of different age groups. The acidic mucins exhibited moderate to intense reaction in new-born and young animals; in adult animals, these were noticed in patches. Neutral and non-sulphated mucins were observed in traces and in mild amounts, respectively, in the mucous secretory end-pieces of different age groups; sialomucins were seen in moderate to intense concentrations. The seromucous end-pieces revealed traces of neutral mucins in new-born buffalo calves and moderate to intense concentrations in young and adult animals. These structures showed mild concentration of acidic mucins, hyaluronic acid and sialomucins. Sulphated and non-sulphated mucins were observed in traces in the seromucous end-pieces. The apical border of the lining cells of the intra- and interlobular ducts contained moderate to intense concentrations of acidic mucins. In young and adult animals, the epithelial cells showed mild to moderate reaction for neutral mucins. Goblet cells of the interlobular ducts exhibited the presence of mild and intense concentrations of sialo- and sulphomucins, respectively.

Age Factors↗
PubMed1976

Mucinous carcinoma of the colon and rectum.

The clinicopathologic significance of mucus production by adenocarcinoma of the colon and rectum was analyzed in retrospective study with stage matched non-mucus producing control carcinomas. Mucinous carcinoma of the colon and rectum comprised 132 (15%) of 893 cases of colorectal carcinoma. The rectum was the most common site (33% of cases). While 120 mucinous cancers had a poorer five-year survival than non-mucinous tumors (34% vs. 53%, p less than .005), these had a particularly bad prognosis in the rectum (18% 5 year survival vs. 49% for the non-mucinous tumor controls, p less than .00k). The theoretical basis for this location-dependent behavior is considered. From this study, distinctive clinico-pathologic features emerge. There were seven documented cases of ulcerative colitis and 8 additional patients gave a history of "colitis". An additional five patients had received prior pelvic irradiation. Of particular note was the fact that 31% of mucinous carcinomas were associated with villous adenomas, implying a histogenetic relationship. Moreover, this finding again emphasizes the neoplastic potential of the villous adenoma, especially in the rectum where the development of mucinous carcinoma is particularly ominous.

Adenocarcinoma, Mucinous↗
PubMed1979

Histochemical characteristics of mucins in the small intestine. A comparative study of normal mucosa, benign epithelial tumours and carcinoma.

The histochemical properties of the mucins in seven benign epithelial tumours and 15 carcinomas distributed along the duodenum, jejunum and ileum were investigated and compared with normal controls. This study reveals that (a) goblet cells in normal small intestine contain neutral and sialomucins but no sulphated material; (b) the proportion of the different types of mucins in the goblet cells vary along the crypts and villi with an increasing amount of sialomucins towards the villus top; (c) mucin composition also changes from duodenum to ileum particularly in the proportions of sialic acid types and in the presence of traces of sulphomucins in the ileal mucosa close to the ileo-caecal valve, suggesting a gradual transition through the small intestine to the colon; (d) benign tumours show the same mucin pattern as normal mucosa; (e) the adjacent to carcinoma shows increasing amounts of sialomucins and sulphomucins; (f) carcinomas present a variety of mucin patterns, and thus the study of mucins seems to be of no value in differentiating tumours of the small intestine from those elsewhere in the gastrointestinal tract. A working hypothesis based on the Unitary Theory of the origin of the intestinal epithelial cells is proposed to explain the variations in glycoprotein synthesis with cell differentiation and carcinogenes.

Adult↗
PubMed1979

Characterization of mucin isolated from rat tracheal transplants.

Subcutaneous rat tracheal grafts yield several milligrams of secretions from which a homogeneous mucin fraction was isolated and purified. Histological evidence demonstrated that a normal mucociliary epithelium and mucous secretion were maintained for the 4-6 weeks of the experiment. The collected secretions were initially characterized by column chromatography on Sepharose CL-6B which separated the excluded high molecular weight mucins (unpurified mucin fraction) from most of the serum-type glycoproteins and proteins, including albumin. A reductive alkylation treatment of the unpurified mucin fraction followed by Sepharose CL-4B chromatography removed contaminating protein and most of the mannose-containing material from the mucin fraction. The void volume material from this column produced a single high molecular weight band upon sodium dodecyl sulfate agarose/acrylamide gel electrophoresis. The purified mucin fraction contained 16.5% protein and primarily galactose, N-acetylglucosamine, N-acetylgalactosamine, and sialic acid. This fraction also underwent beta-elimination in the presence of alkaline borohydride, demonstrating the presence of O-glycosidic linkages.

Amino Acids↗
PubMed1976

Detection of tumor-specific antigens in human mucinous cystadenocarcinoma of the ovary by immunodiffusion.

Rabbit antiserum to a tissue extract of human mucinous cystadenocarcinoma of the ovary reacted with tissue extracts of normal ovary and various ovarian malignancies, and ascitic or cystic fluids of ovarian origin by Ouchterlony double gel diffusion and precipitin inhibition techniques. The tumor-associated antigen(s) of mucinous cystadenocarcinoma, which were demonstrated by Ouchterlony double diffusion, were not present in tissue extract of pooled normal ovaries and cystic fluid of benigh tubo-ovarian cyst. An organ-associated tumor antigen as well as the type-specific tumor antigen may exist in mucinous cystadenocarcinoma of the ovary. The mucinous cystadenocarcinoma was not very immunologically different but was distinguishable from serous cystadenocarcinoma and other types of ovarian cancer by double gel diffusion. Precipitin-inhibition reactions demonstated that the adsorbed antiserum to human ovarian mucinous cystadenocarcinoma mixed with tissue extracts of dysgerminoma and serous cystadenocarcinoma, and ascitic fluid of papillary embryonal adenocarcinoma of the ovary could not eliminate the specific precipin line developed with tissue extract of mucinous cystadenocarcinoma.

Antigens, Neoplasm↗
PubMed1976

Signet-ring cell carcinoma of the breast. The mucinous variant of infiltrating lobular carcinoma?

Five cases of the type of mammary carcinoma that has been designated "signet-ring cell carcinoma" are presented. This tumor is characterized by the presence of numerous cells containing intracellular mucin, without large amounts of extracellular mucin as is seen in colloid (gelatinous, mucinous) carcinoma of the breast. Although such cells may be seen in many mammary carcinomas, they are never as frequent as in the variant described. Ultrastructurally, the most characteristic finding is the presence of numerous intracellular lumina containing material which appears to represent the mucin identified with the light microscope. This finding differs from that in colloid carcinoma, in which the scantier intracellular mucin occurs in the form of intracytoplasmic membrane-bound vesicles. The five tumors in the present series were all associated with either in situ lobular carcinoma or a "sinus catarrh"-like pattern of nodal metastases, or both. On the basis of these light and electron microscopic data, the signet-ring cell carcinoma is suggested as a variant of infiltrating lobular carcinoma, clinically and pathologically distinct from colloid carcinoma.

Adenocarcinoma, Mucinous↗
PubMed1977

Primary mucinous carcinoma of skin: histochemistry and electron microscopy.

Two primary mucinous carcinomas of skin were studied by histochemistry and by light and electron microscopy. Enzyme histochemistry showed a pattern of reactivity similar to that found in eccrine secretory epithelium. Mucin histochemistry substantiated previous reports of probable sialomucin formation. Electron microscopy revealed a highly differentiated neoplasm with a mode of mucin secretion similar to that observed in the dark (mucinous) cell of the eccrine coil. The natural history of mucinous carcinoma of skin indicates that although local growth is the rule, lymph node metastasis may occur.

Adenocarcinoma, Mucinous↗