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PubMed2000

Role of mucus in ischemia/reperfusion-induced gastric mucosal injury in rats.

Gastric mucus plays an important role in gastric mucosal protection. Apart from its "barrier" function, it has been demonstrated that mucus protects gastric epithelial cells against toxic oxygen metabolites derived from the xanthine/ xanthine oxidase system. In this study, we investigated the effect of malotilate and sucralfate (mucus production stimulators) and N-acetylcysteine (mucolytic agent) on ischemia/reperfusion-induced gastric mucosal injury. Gastric ischemia was induced by 30 min clamping of the coeliac artery followed by 30 min of reperfusion. The mucus content was determined by the Alcian blue method. Sucralfate (100 mg/kg), malotilate (100 mg/kg), and N-acetylcysteine (100 mg/kg) were given orally 30 min before surgery. Both sucralfate and malotilate increased the mucus production in control rats. On the other hand, N-acetyloysteine significantly decreased mucus content in control (sham) group. A significant decrease of mucus content was found in the control and the N-acetylcysteine pretreated group during the period of ischemia. On the other hand, sucralfate and malotilate prevented the decrease the content of mucus during ischemia. A similar result can be seen after ischemia/reperfusion. In the control group and N-acetylcysteine pretreated group a significant decrease of adherent mucus content was found. However, sucralfate and malotilate increased mucus production (sucralfate significantly). Sucralfate and malotilate also significantly protected the gastric mucosa against ischemia/reperfusion-induced injury. However, N-acetylcysteine significantly increased gastric mucosal injury after ischemia/reperfusion. These results suggest that gastric mucus may be involved in the protection of gastric mucosa after ischemia/reperfusion.

Animals↗
PubMed1991

Intestinal mucus entrapment of Trichinella spiralis larvae induced by specific antibodies.

Entrapment of muscle larvae (ML) occurred in vitro when antibodies specific for Trichinella spiralis were added directly to intestinal mucus from normal non-immunized rats or when mucus was collected from pups suckling a T. spiralis-infected dam. Normal rat serum immunoglobulins failed to promote mucus entrapment and complement did not appear to play a part in the entrapment process. Differences were not observed in the efficiency of entrapment of ML by mucus harvested from different regions of the small intestine. Employing a panel of monoclonal antibodies (mAb) specific for excretory-secretory antigen (ESA), we attempted to dissociate antibody-mediated protection from mucus entrapment. We assessed mucus entrapment and rapid expulsion by these mAb in vivo, and observed protection in the absence of significant, immediate mucus entrapment in two cases. In addition, we measured mucus entrapment of ML in two in vitro assays. One assay employed intestinal mucus harvested from pups suckling dams that had been injected i.v. with a mAb. Results confirmed those obtained in vivo and indicated that antibodies were present in the intestinal lumina of passively immunized pups. In the second in vitro assay, mAb were added individually to mucus from pups suckling non-immunized dams. Results from these assays suggested that certain antibody isotypes may be processed in vivo in ways that influence, either positively or negatively, their abilities to cause mucus entrapment.

Animals↗
PubMed1987

Rôle of mucus viscoelasticity in clearance by cough.

We examined the relationship between mucus rheology, depth of mucus layer, and clearance by simulated cough. A model trachea constructed of rigid plexiglass was lined with mucus simulants--borate-crosslinked locust bean gum gels. Their viscoelastic properties were determined by magnetic rheometry and expressed as mechanical impedance (dynamic stress/strain ratio or vectorial sum of elasticity and viscosity) and loss tangent (viscosity/elasticity ratio). Cough was simulated by opening a solenoid valve connecting the model trachea to a pressurized tank, using an upstream flow-constrictive element to shape the flow profile to approximate the pattern seen in a normal adult. Mucus clearance was quantitated by observing the movement of contrasting marker particles placed in the mucus layer. The median particle displacement per cough manoeuvre was defined as the clearance index, C.I. We found that C.I., for any initial depth of mucus, increased with the driving pressure in the tank. For a given driving pressure, C.I. increased linearly with increasing mucus depth. For a given driving pressure and depth, C.I. decreased with increasing mechanical impedance of mucus. At constant mechanical impedance, C.I. increased with increasing loss tangent. Mucus clearance was associated with transient wave formation in the lining layer. Thus the dependence on viscoelasticity is consistent with the observations that airflow-mucus interaction and wave formation are impeded by elasticity. The clearance vs. loss tangent relationship for cough is opposite to that found for ciliary clearance, suggesting a natural balance in viscosity and elasticity for mucus to be cleared by both mechanisms.

Airway Resistance↗
PubMedDate not supplied

A planar model for mucociliary transport: effect of mucus viscoelasticity.

A planar two-layer fluid model is proposed to study the transport of mucus in the respiratory tracts due to cilia beating and air motion by considering mucus as a viscoelastic fluid. The effect of air motion due to forced expiration and other processes is considered by prescribing shear stress at the mucus-air interface. It is shown that the transport of mucus increases as the pressure drop, shear stress due to air motion and the velocity generated by cilia tips and the serous sublayer increase. Mucus transport also increases as the shear modulus of elasticity decreases. This property is effective only in the presence of pressure drop or air motion. It is noted that the effect of gravity is similar to pressure drop. It is observed that mucus transport decreases as the viscosity of serous layer fluid increases, but any increase at high values of mucus viscosity does not seem to affect the mucus transport. It is also found that for a given total depth of serous and mucus layers, there exists a serous fluid layer thickness for which the mucus transport is maximum. The functional dependence of mucus transport predicted by the model is discussed in relation to experimental observations.

Elasticity↗
PubMed1993

The pH as an important determinant of sperm-mucus interaction.

OBJECTIVE: To determine the clinical significance of endocervical mucus pH on sperm-mucus interaction during infertility investigation. PATIENTS AND MATERIAL: Two hundred sixteen couples with a median duration of infertility of 4 years (range, 1 to 19 years) presenting at the infertility unit of the Women's University Hospital of Heidelberg, Germany. MAIN OUTCOME MEASURES: Determination of endocervical pH by colorimetric and electrometric measurement and correlation of results with the outcome of postcoital testing (PCT) and other parameters of infertility investigation (semen and cervical mucus [CM] quality, microbial colonization of cervix and ejaculates, medical history, hormonal status, and specific medication) and the subsequent fertility in a prospective study. In vitro experiments with the sperm-cervical mucus penetration test (SCMPT) used as biological model. RESULTS: The colorimetric determination of endocervical mucus pH is an easy method, suitable for routine clinical use, correlating significantly with electrometric measurement of pH. Median pH was 7.0 (range, 5.4 to 8.2). The mucus pH was significantly related with the results of PCT, even when mucus and semen variables were taken into account. No significant relationship was seen between the cervical index and mucus pH and the microbial colonization of cervix and ejaculates. The pH of endocervical secretions correlated with the peripheral hormonal status: low pH levels were significantly more frequent in patients with hyperandrogenemia, indicated by high testosterone and/or dehydroepiandrosterone sulfate levels before medication was started, and in hyperandrogenemic patients treated with dexamethasone than in the other women. Oral administration of estrogens led to a subtle alkalinization of the CM. With regard to subsequent fertility 6 months after pH testing, the pregnancy rate was significantly lower in women offering reduced mucus pH on occasion of the PCT in the group of couples with primary infertility and in couples with oligozoospermia of the male partner. The significant influence of pH on sperm-mucus interaction was confirmed in vitro with the SCMPT. CONCLUSIONS: The results indicate that the pH of the CM, easily determined with pH indicator paper, is an important parameter of mucus quality with significant influence on spermatozoal viability in CM, which correlates with peripheral hormonal status and can be affected by oral medication with estrogens. Therefore the routine determination of pH on occasion of the PCT is recommended during infertility investigation.

Adult↗
PubMed2004

Adhesion properties of enterococci to intestinal mucus of different hosts.

The adhesive capacity of selected enterococci to human, canine and porcine intestinal mucus was investigated in order to select for potential probiotic strains with good adhesive properties for human or animal use. The adhesion to the human intestinal mucus of the tested strains was found to range from log10 3.8 to log10 8.6 cfu per microtitre plate well. The highest adhesion to the human intestinal mucus was found among strains from horse faeces, dog faeces and dog feed. The adhesion to canine mucus was observed to range from log10 3.8 to log10 8.3 cfu/well, with the highest adhesive capacity among strains from dog faeces, horse faeces and dog's feed; on average log10 7.9, 7.3 and 7.0 cfu/well, respectively. Isolates from dogs did not bind at higher levels to canine mucus than to human mucus. A strong correlation was observed for the adhesion to human and canine intestinal mucus (p < 0.0001) and also between porcine and canine or human mucus (p < 0.05 for both). When comparing the adhesion of Enterococcus faecium and E. faecalis, no statistical significant differences were observed for any of the tested mucus types. The tested Enterococcus strains were found to exhibit a strain dependent on in vitro adhesion to human, canine and porcine intestinal mucus and did not exhibit host specificity in their adhesion, though some sources appeared to contain more adhesive strains than others. To our knowledge, this is the first report on the in vivo adhesion to intestinal mucus of a large number of enterococci from different sources.

Animal Feed↗
PubMed1999

In vivo distribution of Helicobacter felis in the gastric mucus of the mouse: experimental method and results.

We describe a method that permits the collection of very small samples (2 nl) from precisely defined positions within the gastric mucus of anesthetized mice. This method was used to study the in vivo local distribution of bacteria within the mucus of Helicobacter felis-infected mice. A total of 200 samples from 40 mice were analyzed. Each sample was microscopically analyzed, within less than 1 min, as a native preparation. To avoid changes in bacterial location within the mucus after collection and to improve the counting accuracy, bacterial motility was blocked by adjusting the pH inside the collecting pipette to 4.5. The mucus in a collected sample was subdivided into three layers, an epithelial layer (the first 25 micron of mucus from the tissue-mucus interface), a luminal layer (the last 25 micron to the mucus-lumen interface), and the remaining central mucus layer. The volume of the analyzed segments in the sample was between 4 and 9 pl. The concentration of bacteria inside the epithelial mucus layer was 3,400 per nl, but it was only 50 per nl inside the central mucus layer. The mean distance of H. felis to the epithelial surface was 16 microm. A total of 75% of all H. felis bacteria resided in the mucus zone between 5 and 20 micron from the tissue surface, with no bacteria closer than 5 micron to the epithelial surface. This method permits the study of factors determining the density of colonization and distribution of bacteria along chemical gradients with a high precision.

Animals↗
PubMedDate not supplied

The adherent gastric antral and duodenal mucus gel layer thins with advancing age in subjects infected with Helicobacter pylori.

BACKGROUND: Peptic ulceration and Helicobacter pylori infection increase with advancing age. In the upper gastro-intestinal tract the first line of mucosal defence is the adherent mucus gel layer. OBJECTIVE: We have examined, using a novel histological fixation technique, the thickness of the adherent mucus gel layer (1) in the gastric antrum and (2) in the duodenum in relation to advancing age and H. pylori status. METHODS: The subjects had macroscopically normal stomach and duodenum at endoscopy. Measurement of the gastric antral mucus thickness was carried out on four antral biopsy specimens from within 2 cm of the pylorus (H. pylori positive n = 25, negative n = 21). The duodenal mucus thickness (D1) was measured from two biopsy specimens (H. pylori positive n = 7, negative n = 13). All specimens were snap frozen and cryostat sections stained using a modified PAS/AB stain. RESULTS: In all sections the mucus layer was continuous. In both duodenum and gastric antrum, the mucus thickness was not significantly different between H. pylori positive and H. pylori negative age-matched samples. In duodenum and gastric antrum from H. pylori negative subjects, there was no correlation between mucus thickness and age. However, in H. pylori positive subjects, there was a significant thinning of the adherent gastric antral mucus gel layer (p = 0.005, r = -0.54) and the duodenal mucus thickness (p<0.001, r = -0.99) with advancing age. CONCLUSION: This study shows a significant thinning of the adherent mucus gel layer in H. pylori positive individuals, as stomach and duodenum age. In those without H. pylori, the mucus gel thickness is preserved in stomach and duodenum.

Aged↗
PubMed1996

Temporal relationship between Uniplant insertion and changes in cervical mucus.

This study was undertaken to determine the time required by a single implant containing nomegestrol acetate to affect cervical mucus production and sperm penetration in women. All subjects were investigated and, if necessary, treated for any kind of cervicitis or vaginitis prior to starting cervical mucus study. The subjects had not used hormonal contraception for at least three months prior to investigation. They were counseled to use condoms during this study and also to refrain from intercourse during the period of cervical mucus sampling. Follicular development and endometrial thickness were analyzed by transvaginal sonography. Cervical mucus examination, sperm penetration test, and transvaginal sonography were performed during the control cycle and during the first cycle of Uniplant use. Blood samples were taken for the measurement of estradiol, LH, and progesterone. Cervical mucus and sperm penetration tests were evaluated according to the World Health Organization (WHO) criteria. In the treated cycle, when cervical mucus reached a score of 8-10, Uniplant was inserted, independent of the day of the cycle. Cervical mucus was then collected at 0, 4, 8, 12, 24, 48, and 96 h later until a marked change in volume, consistency, ferning spinnbarkheit, and cellularity was observed. All samples were also used for sperm penetration test. Preovulatory estradiol and LH peak decreased significantly compared to pre-implant insertion. Progesterone levels were within the normal limit. Cervical mucus and sperm penetration tests were not affected by Uniplant in the first 12 h. Twenty-four hours after Uniplant insertion, cervical mucus and sperm penetration tests were affected in 70.6% of the women. Forty-eight hours after implant insertion, the women were affected. Follicular rupture occurred in the majority of the women 48 h after implant insertion. Based on these results, it is possible to conclude that Uniplant can affect estradiol and LH preovulatory peaks and disrupt the process of cervical mucus production and sperm penetration, but it was unable to prevent ovulation when inserted in the preovulatory phase.

Adult↗
PubMed1989

Changes in cervical mucus that prevent penetration by spermatozoa.

Two situations that result in the conversion of human mid-cycle cervical mucus from a sperm-receptive to a sperm-hostile form are described here: firstly, the addition of mucospissic agents, and secondly, the presence of antisperm antibodies. Two mucospissic biguanides were studied, chlorhexidine and Vantocil; both were totally spermicidal in the range 1-10 mg ml-1. Treatment of mucus with 1.5 microM to 1.65 mM Vantocil caused a dose-dependent increase in the dynamic storage modulus. The compatibility of the two biguanides with mucus was examined by measuring the rate of entry of diffusion of the [14C]biguanides into mucus. Chlorhexidine entered the mucus up to 0.53 mM, i.e. the highest concentration used, whilst Vantocil only entered at concentrations below 0.53 mM. This limited entry may be caused by the precipitation of mucus at the interface, producing a barrier of reduced permeability. The behaviour of purified mucin on ultracentrifugation was also altered after treatment with chlorhexidine. The s20 (at 2 mg ml-1 purified mucin) increased from 11.2 S to 19.3 S upon addition of 200 microM chlorhexidine. Further indication of structural alteration of biguanide-treated mucin was given by its loss of solubility in 0.22 M-sodium thiocyanate. The application of these biguanides to vaginal contraception is suggested. When antisperm antibodies are present in either the semen or cervical mucus, we suggest that an interaction can occur between galactose residues on the spermatozoa and galactose recognition sites on the antisperm antibody; in addition, binding can also occur between the Fc region of the antibody and cervical mucus. This process could therefore contribute to the binding of spermatozoa to the antibody and the immobilisation of this complex by the cervical mucus that is seen in immunological infertility. It was shown, by Immunobead binding, that immediate exposure of spermatozoa to D-galactose in the presence of chymotrypsin resulted in a considerable decrease or total loss of bound antisperm antibodies in males who had previously had a high titre of antibody. This reduction in the antibody level on the spermatozoa was accompanied by the appearance of the antibody level on the spermatozoa was accompanied by the appearance of the ability of the spermatozoa to penetrate cervical mucus in those couples examined. This pretreatment regimen for the ejaculate is suggested as a form of therapy for infertility related to the presence of antisperm antibodies.

Antibodies↗
PubMed2003

Fetal cells in cervical mucus in the first trimester of pregnancy.

OBJECTIVES: The aim of this study was to first evaluate the presence of fetal cells in cervical mucus samples collected in the first trimester of pregnancy and then to compare different laboratory methods for the detection of these cells. METHODS: Mucus samples were collected by using a cytobrush before termination of pregnancy (TOP) from 143 pregnant women between 7 and 12 weeks of gestation. None of the women had undergone an invasive diagnostic procedure prior to cervical mucus sampling. Samples of placental tissue were collected from each patient at TOP. Slides from each sample were first observed under an inverted microscope to detect possible sperm contamination. In the first part of our experiments, 40 mucus samples were treated with a mucolytic solution containing N-acetylcysteine (AC) and were analysed by a polymerase chain reaction (PCR) assay. The second series, consisting of 71 mucus samples, was treated with a mucolytic solution containing dithiothreitol (DTT): all 71 samples were analysed by a PCR-based assay, and an aliquot for fluorescent in situ hybridisation (FISH) analysis was also obtained from 48 out of 71 samples. In the third part of our experiments, performed on 32 mucus samples, mucus trapped on the cytobrush was directly spread on two slides for FISH analysis without any mucolytic treatment. All placental tissue samples obtained at termination were analysed by FISH for fetal sexing. RESULTS: Overall, the use of PCR-based or FISH analyses on 143 mucus samples resulted in correct sex prediction in 92/143 (64.3%) samples [20/66 (30.3%) cases from known male pregnancies and 72/77 (93.5%) cases from known female pregnancies]. In the AC group, Y-derived sequences were found in 7/23 samples (30.4%) from known male pregnancies and in 1/17 cases from known female pregnancies, with an overall correct sex prediction in 23/40 cases (57.5%). In the DTT group, Y-derived sequences could be amplified in 10/30 samples (33.3%) from known male pregnancies and in 4/41 cases from known female pregnancies, with an overall correct sex prediction in 47/71 cases (66.2%). In the DTT samples analysed by FISH, nuclei bearing XY signals were detected in 5/26 (19.2%) cases from known male pregnancies and in none from female pregnancies, the rate of correct sex prediction being 56.2% (27/48). On untreated mucus samples analysed by FISH, nuclei with XY signals were documented in 3/13 (23%) samples from male conceptuses and in none from known female pregnancies, with an overall correct sex prediction in 22/32 cases (68.7%). CONCLUSION: Fetal cells were not detected in a constant and reliable fashion in cervical mucus samples collected in the first trimester of pregnancy. The detection rate was poorly influenced by the use of different laboratory methods. This sampling technique cannot be regarded as a promising tool towards minimally invasive prenatal diagnosis.

Adult↗
PubMed1994

Leukocytes migrate through three-dimensional gels of midcycle cervical mucus.

The migration of leukocytes through mucus must be an essential factor in the mucosal immune response, particularly during mucosal invasion by pathogens. We used two methods to evaluate the ability of neutrophils to migrate through human midcycle cervical mucus: (i) direct visualization of cell migration within freshly collected mucus samples and (ii) quantification of cell penetration through a layer of mucus overlying a monolayer of cultured intestinal epithelial cells from the T84 cell line. Neutrophils migrated rapidly through human midcycle cervical mucus: the random motility coefficient (mu) ranged from 1.2 to 5.6 x 10(-8) cm2/sec in different mucus samples. The rate and pattern of neutrophil migration in cervical mucus were identical to those in a structurally similar collagen gel (0.4 mg/ml). Therefore, we also quantitatively examined the migratory behavior of human neutrophils, monocytes, and lymphocytes from peripheral blood, as well as leukocytes isolated from semen, in collagen gels as a model of cell migration in cervical mucus. In the absence of stimulation, mu was approximately 10(-8) cm2/s for neutrophils and lymphocytes; monocytes and seminal leukocytes were immotile. In all cases, mu increased with the addition of FMLP. Furthermore, neutrophils were able to penetrate layers of mucus overlying monolayers of T84 cells when the gel thickness was less than approximately 500 microns. These results suggest that leukocytes migrate effectively through mucus, a process which may be related to their ability to function in the mucosal immune system or to serve as vectors for the translocation of infectious pathogens like HIV.

Cell Movement↗
PubMed2001

KDN-containing glycoprotein from loach skin mucus.

It has been widely recognized that the mucus coat of fish plays a variety of important physical, chemical, and physiological functions. One of the major constituents of the mucus coat is mucus glycoprotein. We found that sialic acids in the skin mucus of the loach, Misgurnus anguillicaudatus, consisted predominantly of KDN. Subsequently, we isolated KDN-containing glycoprotein from loach skin mucus and characterized its chemical nature and structure. Loach mucus glycoprotein was purified from the Tris-HCl buffer extract of loach skin mucus by DEAE-cellulose chromatography, Nuclease P1 treatment, and Sepharose CL-6B gel filtration. The purified mucus glycoprotein was found to contain 38.5 KDN, 0.5% NeuAc, 25.0% GalNAc, 3.5% Gal, 0.5% GlcNAc and 28% amino acids. Exhaustive Actinase digestion of the glycoprotein yielded a glycopeptide with a higher sugar content and higher Thr and Ser contents. The molecular size of this glycopeptide was approximately 1/12 of the intact glycoprotein. These results suggest that approximately 11 highly glycosylated polypeptide units are linked in tandem through nonglycosylated peptides to form the glycoporotein molecule. The oligosaccharide alditols liberated from the loach mucus glycoprotein by alkaline borohydride treatment were separated by Sephadex G-25 gel filtration and HPLC. The purified sugar chains were analyzed b --> 6GalNAc-ol, KDNalpha2 --> 3(GalNAcbeta1 --> 14)GalNAc-ol, KDNalpha2 --> 6(GalNAcalpha1 --> 3)GalNAc-ol, KDNalpha2 --> 6(Gal3alpha1--> 3)GalNAc-ol, and NeuAcalpha2 --> 6Gal NAc-ol. It is estimated that one loach mucus glycoprotein molecule contains more than 500 KDN-containing sugar chains that are linked to Thr and Ser residues of the protein core through GalNAc.

Amino Acids↗
PubMedDate not supplied

Duct ectasia due to mucus-producing cancers with intraductal extension: histopathologic correlation with radiologic imagings.

BACKGROUND: Although duct ectasia due to mucus-producing pancreatic cancer has been well known, its occurrence in other organs has not been reported. We have studied the pathologic basis of the radiologic features in cases of mucus-producing cancer with intraductal extension. METHODS: We conducted a comparative study of detailed various radiographic images and pathological findings in 10 cases of mucus-producing cancers (four of mucus-producing pancreatic cancer, two of mucinous gastric cancer with diffuse lymphangitic liver metastasis, and four cases of bronchoalveolar cell carcinoma with cyst or cavity). RESULTS: When mucus-producing cancer occurs in a secretory duct or extends into lymphatic ducts, the normal duct is dilated due to the mucus and increased internal pressure, leading to the formation of a cyst and cavity. Because of having the liquid property of mucus floating cancer cells, the lesion can easily progress to continuous ducts as well as regionally. CONCLUSIONS: In cases of mucus-producing cancer with extension into the ductal structure not only in the pancreas but also in the lung and liver, continuous duct ectasis and cysts filled with mucus or cavities of all sizes made by the nature of the mucus may be detected by CT and US.

Adenocarcinoma, Bronchiolo-Alveolar↗
PubMed1985

Adherent and soluble mucus in the stomach and duodenum.

Gastroduodenal mucus is present as a water insoluble gel adherent to the mucosal surface and as a viscous mobile solution in the lumen. The protective properties of the mucus against acid (with bicarbonate), pepsin (diffusion barrier) and mechanical damage depend on the quality (structure) and quantity (thickness) of the adherent mucus gel layer. Adherent mucus is a viscoelastic gel which is 95% (v/v) water. It is permeable to ions and smaller molecules (Mr c. 1000), but is impermeable to large proteins (Mr c. 17,000) including pepsins. However, mucus is solubilized rapidly by pepsin, more slowly (greater than or equal to 1 h) by thiol agents, and is unchanged following exposure to bile, acid and ethanol (less than 40%). Glycoprotein macromolecules (Mr greater than or equal to 2 X 10(6] are the structural components of the mucus gel and have a polymeric structure of glycoprotein subunits (Mr c. 5 X 10(5), for gastric mucus) joined by disulphide bridges between their protein cores. This glycoprotein polymerization, which is essential for gel formation and hence function, is the site of action of proteolytic enzymes and thiol agents. The glycoprotein polymeric structure is deficient in antral mucus from patients with peptic ulcer disease. In vivo, adherent mucus forms a thin but continuous cover of variable thickness (50-450 micron in man, about two-fold less in rat) over the gastroduodenal mucosa. Pepsin in gastric juice will rapidly dissolve this mucus cover and can be active up to luminal pH values of 5.(ABSTRACT TRUNCATED AT 250 WORDS)

Adhesiveness↗
PubMed1983

Lipids associated with rat small-intestinal mucus glycoprotein.

The lipid content and composition of rat small-intestinal mucus, and the purified mucus glycoprotein before and after Pronase digestion were investigated. The mucus, obtained by the instillation of intestine with 2M NaCl, was fractionated on Bio-Gel A-50 in the presence of 6M urea and the mucus glycoprotein free of noncovalently bound protein was isolated. A portion of the purified glycoprotein was subjected to Pronase digestion to yield glycopeptides. The native mucus, and the purified glycoprotein and glycopeptides were extracted with chloroform-methanol, and the lipids contained in the extracts were analyzed. The lipids accounted for 17.6 of the dry weight of mucus, 26.4 of the mucus glycoprotein, and 25.3% of the glycopeptides. In comparison to mucus, the lipids associated with mucus glycoprotein contained 1.9 times more phospholipids and 2.1 times more glycolipids, showed a 26% increase in neutral lipids, and were virtually free of glycosphingolipids. Treatment of the purified glycoprotein with Pronase led to a moderate (22.3%) loss in neutral lipids, 4.3-fold decrease in phospholipids, and 52.3% increase in glyceroglucolipids. The results indicate that while the interaction of mucus glycoprotein with phospholipids involves its Pronase-susceptible region, the interaction with glyceroglucolipids occurs in the glycosylated region of the glycoprotein that is resistant to proteolysis.

Animals↗
PubMed1985

Alteration of airway reactivity by mucus.

In 11 beagles with permanent tracheostomies we investigated whether mucus hypersecretion alters airway reactivity to inhaled aerosols. Mucus was collected from the dogs while awake by resting a cytology brush on the lower tracheal mucosa; the mucus collection rate was used as an index of mucus flux. Mucus linear velocity was determined under light sedation by bronchoscopically observing the rate of particle clearance in the trachea. Mucus depth was then computed from the flux and velocity. On a separate occasion, under pentobarbital anesthesia, methacholine aerosols (1 min duration) were given at 10 min intervals in doubling doses up to at least 2 mg/ml. Pulmonary resistance RL was determined prior to and 2 min after each dose. After a 1 h pause, methacholine was infused at a constant rate of 40 micrograms X kg-1 X min-1 for 10 min. This dose produced a plateau in RL after approximately 3 min; the mean rise in RL was similar to that achieved with the 2 mg/ml aerosol. The infusion response Rinf was defined as the change in RL 4-5 min post infusion; the aerosol response Raer was defined as the change in RL 2 min post 2 mg/ml aerosol. There was no significant correlation between Rinf and Raer, nor between either Rinf or Raer and mucus flux. There was, however, a strong positive association between Rinf/Raer and mucus flux and a similar positive association between Rinf/Raer and mucus depth. These associations indicate that dogs with elevated secretion levels are relatively unresponsive to aerosolized as opposed to infused methacholine. Thus, to the extent that infusion reactivity reflects innate airway reactivity, the reactivity to inhaled aerosol may underestimate the true value when mucus hypersecretion occurs.

Aerosols↗
PubMed1998

Viscoelastic properties of canine tracheal mucus: effects of structural inhomogeneities and storage.

Tracheal mucus is an inhomogeneous material and thus its viscoelastic properties may vary substantially within a mucus sample. In this study on canine tracheal mucus, we investigated this variation of mucus viscoelasticity and addressed the question whether or not the viscoelasticity is affected by storage of the mucus at low temperatures. Mucus samples were collected from 16 beagle dogs kept under clean air conditions. By means of magnetic rheometry, dynamic viscosity- and elasticity were determined either in the fresh state of these samples or after storage at -80 degrees C. Owing to inhomogeneities within the gel-structure of the mucus, local values of the viscoelastic parameters differed by more than an order of magnitude. Short storage periods (5 d) were found to decrease, long periods (100 d) to increase the viscosity as well as elasticity parameters of the mucus material. These results emphasize the fact that measured viscoelastic properties of mucus are average values depending on the measuring protocol. In addition, these values are modified by storage of the mucus at low temperatures.

Animals↗