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Biomedical subjects

J P Pearson

Publications and source records attributed to J P Pearson.

At least 19 recordsLinked to original sources
PubMed2005

Pepsin like activity in bronchoalveolar lavage fluid is suggestive of gastric aspiration in lung allografts.

BACKGROUND: A biologically plausible link between gastro-oesophageal reflux (GOR), aspiration, and lung allograft dysfunction has been suggested, but there is no systematic evidence indicating the presence of gastric contents in the lung. We have tested the hypothesis that pepsin, as a marker of aspiration, is detectable in bronchoalveolar lavage (BAL) fluid of allograft recipients who had not reported symptoms of GOR. METHODS: Standardised 3 x 60 ml surveillance BAL fluid samples from 13 chronologically sequential stable lung allograft recipients without chronic rejection (10 patients treated with a prophylactic proton pump inhibitor) were studied. Lavage supernatants were assayed by an ELISA based on a monospecific goat antibody for pepsin/pepsinogen. Pepsin levels were compared with those from four normal volunteer controls. RESULTS: Pepsin levels were measurable in all allograft recipients, in keeping with gastric aspiration (median 109 ng/ml (range 35-1375)). In the control group the pepsin levels were below the limit of detection. Treatment with a proton pump inhibitor was not correlated with pepsin levels. There was no correlation between BAL fluid neutrophils and pepsin levels. CONCLUSION: These data demonstrate lung epithelial lining fluid concentrations of pepsin in lung allograft recipients which are much higher than blood reference levels, with no detectable pepsin in controls. This provides direct evidence of gastric aspiration, which is potentially injurious to the allograft.

Adult↗
PubMed2005

Alginate as a source of dietary fiber.

Alginate, an algal polysaccharide, is widely used in the food industry as a stabilizer, or as a thickening or emulsifying agent. As an indigestible polysaccharide, alginate may also be viewed as a source of dietary fiber. Previous work has suggested that dietary fibres may protect against the onset and continuation of a number of cardiovascular and gastrointestinal diseases. This article aims to examine what is currently understood about the fiber-like activities of alginate, particularly its effects on intestinal absorption and the colon, and therefore aims to gauge the potential use of alginate as a dietary supplement for the maintenance of normal health, or the alleviation of certain cardiovascular or gastrointestinal diseases.

Alginates↗
PubMed2005

The bladder does not appear to have a dynamic secreted continuous mucous gel layer.

PURPOSE: We determined whether the nature of any protective barrier in the bladder is composed of a secreted mucous gel layer. MATERIALS AND METHODS: We collected 24-hour urine samples for analysis from 8 healthy 22 to 49-year-old volunteers and 5, 19 to 59-year-old patients treated with bladder reconstruction, in addition to scrapings from 100 freshly slaughtered pig bladders. Samples were subjected to homogenization, dialysis, freeze-drying, papain digestion, gel chromatography, equilibrium density gradient centrifugation, periodic acid-Schiff assay and amino acid analysis. Normal human bladder, pig bladder, normal ileum and transposed intestinal segments were studied for the presence of a mucous layer using a new method of histological analysis. RESULTS: Mucin content in normal urine is 2.7 mg/24 hours, meaning that less than 0.6% of nondialyzable material in normal urine is mucin. The mucin content of urine from reconstructed bladders amounted to 86 mg/24 hours (5.2% of nondialyzable material). We observed that glycosaminoglycans accounted for 41% of the peak total elution volume of PAS positive material in normal urine. Mucin estimation in urine can be grossly overestimated if contaminating glycoconjugates are not removed. Biochemical analysis of material scraped off the pig bladder surface demonstrated that the maximum thickness of a continuous layer that could be achieved was 13.6 mum. While we could visualize an obvious mucous layer on control ileal samples and biopsies of transposed ileal segments from patients with bladder reconstruction, we were unable to note a distinct, measurable mucous layer lining the bladder surface in humans or pigs. CONCLUSIONS: Mucin levels in normal human and pig urine would be enough for slow turnover of a thin barrier but the large increase in mucin in the urine of patients with transposed intestinal segments demonstrates that any layer in normal bladder is much different than that lining the transposed intestinal segment. The most likely constituents of this barrier are membrane bound rather than secreted mucins along with the proteoglycan components of the glycocalix.

Adult↗
PubMed2004

Is otitis media with effusion a biofilm infection?

Recent attention has focused on the possibility that otitis media with effusion (OME) may represent a chronic infective state such as those evidenced in conditions secondary to biofilms or small colony variants. This review discusses the evidence suggesting that this may indeed be the case and explains why this may prove to be important in the future management of this condition by discussing recent advances in understanding these bacterial phenotypic variants.

Bacterial Adhesion↗
PubMed2003

Influence of prednisolone on the secretion of mucin from the HT29-MTX cell line.

Glucocorticoids have been used in the treatment of otitis media with effusion with promising but inconsistent results. The HT29-MTX cell line is a completely differentiated and almost exclusively mucus-secreting goblet cell line. To assess the potential of steroids in suppressing mucin secretion, we have studied the response of this cell culture to prednisolone. Confluent cell cultures were trypsinized, subcultured in six-well plates and incubated with five doses of prednisolone from 10-3 M to 10-11 M and over a varying time course from 6 to 36 h. Analysis was performed using a monoclonal mouse antibody to human gastric mucin by dot-blot ELISA. Prednisolone caused a consistent reduction in mucin production from this cell line. Increasing concentrations of prednisolone resulted in increasing suppression of MUC5AC secretion. There is a dose-dependent suppression of mucin secretion by prednisolone, with a maximum effect of 21% over control seen at the highest steroid concentration used.

Anti-Inflammatory Agents↗
PubMed2003

Effect of nitric oxide donation on mucin production in vitro.

Otitis media with effusion (OME) is characterized by the accumulation of a viscous fluid rich in mucins in the middle ear cleft. There is increasing evidence that this fluid is the result of an inflammatory reaction and that nitric oxide (NO) is an important mediator in this reaction. The goblet cell line HT29-MTX produces principally MUC5AC, an important mucin in middle ear effusions, and thus is a good model for the study of mucus-secreting epithelia. Confluent cell cultures were trypsinized, subcultured and incubated with isosorbide dinitrate (ISDN), a NO donor, for 0.5, 1 and 2 h at a concentration of 1 mm and in concentrations of 0.01, 0.1, 0.5, 1 and 2 mm for 1 h. Experiments were performed four times. Mucin production was detected by a slot blot ELISA assay, using a monoclonal mouse antibody to human MUC5AC mucin. Statistical significance was tested using a one-way analysis of variance. NO donation by ISDN caused a consistent rise in mucin production above control. Maximal mucin production of 35% above control occurred at 1 h with 1 mm ISDN. Mucin production increased from 12% above control with 0.1 mm ISDN dinitrate to 45% above baseline with 2 mm ISDN. NO donation by ISDN results in an increase in mucus production, which is both dose and time related. This adds further evidence to an inflammatory model for mucus secretion in OME.

Antibodies, Monoclonal↗
PubMed2003

Characterization of Escherichia coli strains causing urinary tract infections in patients with transposed intestinal segments.

PURPOSE: Transposition of intestinal segments into the urinary tract predisposes to urinary tract infections. We characterized bacterial infections in these patients and examined the virulence genotype and persistence of Escherichia coli isolates. MATERIALS AND METHODS: We followed 26 patients who underwent bladder reconstructive surgery using transposed intestinal segments. E. coli strains isolated from the urine of these patients were genotyped for established virulence determinants and the frequency of carriage was compared with E. coli strains isolated from community acquired urinary infections and the fecal flora of anonymous volunteers. A longitudinal study of E. coli strains in 9 patients was also done using pulsed field gel electrophoresis. RESULTS: E. coli was the most frequently isolated organism, responsible for 59% (62 of 105) of monobacterial infections. Other bacteria isolated included Klebsiella species, Proteus species and Enterococcus faecalis. Community acquired E. coli strains were more likely to carry multiple determinants for particular adhesins (P and S fimbriae) and toxins (alpha-hemolysin and cytotoxic necrotizing factor) than fecal strains. Carriage frequency for bladder reconstruction strains was intermediary and not significantly different. The key finding was that E. coli strains persisted for prolonged periods, including 2 years in certain patients, often despite various antimicrobial treatments. CONCLUSIONS: This study highlights that further steps must be taken to prevent and treat urinary tract infections in this susceptible group. Particular attention should be given to the treatment of persistent infections.

Adult↗
PubMed2001

MUC1 expression in primary breast cancer: the effect of tamoxifen treatment.

This was a non-randomised single institution retrospective study. Forty-six banked frozen tumour specimens were obtained from a group of patients who had undergone 3 weeks of neoadjuvant treatment with tamoxifen between biopsy and surgery. Fifty-one comparison specimens were randomly selected from a group of concomitantly treated primary breast cancer patients who did not receive neoadjuvant tamoxifen. Specimen selection was not based on prognostic factors: hormone receptor status, patient age, or menopausal status. MUC1 expression and cell cycle distribution were assessed by flow cytometry. S-phase fraction of MUC1 positive and MUC1 negative cells were compared. A lower percentage of cells expressed MUC1 following 3-week tamoxifen treatment 18.2% versus 28.5% (p = 0.03, Mann-Whitney) and lower levels of MUC1 expression were seen following tamoxifen treatment 31,519 molecules/cell versus 39,387 (p = 0.04, Mann-Whitney). MUC1 positive cells, irrespective of treatment group, had a greater proportion of cells in S-phase of the cell cycle 27.9% versus 16.8% (p = 0.0004, Mann-Whitney) and demonstrated more cases of aneuploidy 80.65% versus 42.6% (p < 0.0001). MUC1 levels in primary tumours treated neoadjunctively with 3 weeks of tamoxifen were lower than a comparison group which did not receive tamoxifen. MUC1 should be explored further as an intermediate biomarker for assessment of treatment and prognosis.

Aged↗
PubMed2001

Esophageal mucin: an adherent mucus gel barrier is absent in the normal esophagus but present in columnar-lined Barrett's esophagus.

OBJECTIVES: The presence of a protective adherent mucus gel barrier against gastric reflux in the healthy esophagus is uncertain. The aim was to characterize the surface mucin composition and determine the extent of any adherent mucus gel layer on the normal esophagus, and compare this with that in Barrett's esophagus. METHODS: Isolated surface mucins were characterized by density centrifugation, gel filtration chromatography, and chemical composition. Adherent surface mucus was visualized in situ on unfixed and cryostat sections of mucosa and biopsies using a method that preserves mucus layer thickness. RESULTS: There was a complete absence of adherent mucus gel layers on normal human, pig, and rat esophagi. This was in contrast to the thick adherent mucous layer (median thickness = 100-200 microm) seen on the corresponding gastric mucosa. Small quantities of glycoprotein with a composition characteristic of a secretory mucin were isolated from the pig esophagus surface. The mucin, density range between 1.44 and 1.48 g x ml(-1), contained 80% carbohydrate and was rich in serine, threonine, and proline. The mucin fragmented into smaller glycoprotein units on proteolysis and partially on reduction. Cryostat sections from columnar-lined esophageal biopsies had a substantial adherent surface mucous layer (median thickness = 90 microm, interquartile range = 84-94 microm) staining for neutral mucins (gastric-type epithelium) and acidic mucins (intestinal metaplasia). CONCLUSIONS: A secretory mucin, with an analysis distinct from that of gastric or salivary mucin, is present in very small quantities on the esophageal mucosa and in amounts insufficient to form an adherent gel layer. It is unlikely that mucus has a role in protecting the normal esophagus against reflux. However, an adherent mucous layer was observed over columnar-lined esophagus, and this may protect against reflux.

Animals↗
PubMed2001

Inhibition of quorum sensing by a Pseudomonas aeruginosa dksA homologue.

The Pseudomonas aeruginosa las (lasR-lasI) and rhl (rhlR-rhlI) quorum-sensing systems regulate the expression of several virulence factors, including elastase and rhamnolipid. P. aeruginosa strain PR1-E4 is a lasR deletion mutant that contains a second, undefined mutation which allows production of elastase and rhamnolipid despite a nonfunctional las system. We have previously shown that this strain accomplishes this by increasing the expression of the autoinducer synthase gene rhlI. In this report, we show that the elastolytic phenotype of mutant PR1-E4 can be complemented with a P. aeruginosa homologue of the Escherichia coli dnaK mutation suppressor gene dksA. When supplied in trans on a multicopy plasmid, this gene completely suppressed elastase production by mutant PR1-E4. Cloning and Northern blot analysis revealed that dksA was neither mutated nor less transcribed in mutant PR1-E4. When overexpressed, dksA also reduced rhamnolipid production by both mutant PR1-E4 and the wild type, PAO1. Using Northern blot analysis and lacZ reporter fusions, we show that dksA inhibits rhlI, rhlAB, and lasB transcription. Exogenous N-butyryl-L-homoserine lactone overcame the reduced expression of rhlI and restored rhlAB and lasB expression, as well as elastase production. Our results suggest that the overproduction of the P. aeruginosa DksA homologue inhibits quorum-sensing-dependent virulence factor production by downregulating the transcription of the autoinducer synthase gene rhlI.

Bacterial Proteins↗
PubMed2001

Cell biology of laryngeal epithelial defenses in health and disease: preliminary studies.

Esophageal epithelium has intrinsic antireflux defenses, including carbonic anhydrases (CAs I to IV) that appear to be protective against gastric reflux. This study aimed to investigate the expression and distribution of CA isoenzymes in laryngeal epithelium. Laryngeal biopsy specimens collected from the vocal fold and interarytenoid regions were analyzed by Western blotting and immunofluorescence. Carbonic anhydrases I and II were expressed by the majority of samples analyzed. In contrast, CA III was differentially expressed in the interarytenoid samples and was not detected in any vocal fold samples. The expression of CA III was increased in esophagitis as compared to normal esophageal tissue. Carbonic anhydrase I and III isoenzymes were distributed cytoplasmically in the basal and lower prickle cell layers. The laryngeal epithelium expresses some CA isoenzymes and has the potential to protect itself against laryngopharyngeal reflux. Laryngeal tissue may be more sensitive to injury due to reflux damage than the esophageal mucosa because of different responses of CA isoenzymes.

Acid-Base Equilibrium↗
PubMed2001

Mucosal protective effects of ecabet sodium: pepsin inhibition and interaction with mucus.

Pepsin, acid and Helicobacter pylori are major factors in the pathophysiology of peptic ulcer disease and reflux oesophagitis. Ecabet sodium reduces the survival of H. pylori in the stomach and inhibits pepsin activity in the gastric juice of experimental animals. Here we have investigated the effects of ecabet sodium on some of the factors involved in the dynamics of the mucosal barrier, i.e. pepsins and mucins. This study used gastric juice obtained from 12 non-symptomatic volunteers and nine patients with reflux oesophagitis. Ecabet sodium significantly inhibited pepsin activity in human gastric juice, with a maximum inhibition of 78%. Pepsin 1, the ulcer-associated pepsin, was inhibited to the greatest extent. The ability of gastric juice to digest mucin was significantly inhibited by ecabet. As with gastric juice proteolytic activity, the inhibitory effect of ecabet on mucolysis was greater in gastric juice from patients with reflux oesophagitis than in that from controls. Ecabet sodium showed a positive interaction with gastric mucin, as assessed by an increase in viscosity. Thus ecabet sodium may reduce the aggressive potential of gastric juice towards the mucosa, which may be relevant in the treatment of reflux oesophagitis and peptic ulcer disease. In addition, it may strengthen the mucus barrier in peptic ulcer disease and gastritis.

Abietanes↗
PubMed2001

Up-regulation of mucin secretion in HT29-MTX cells by the pro-inflammatory cytokines tumor necrosis factor-alpha and interleukin-6.

The pro-inflammatory cytokines IL-6 and TNF-alpha have been implicated in the pathogenesis of otitis media with effusion (OME). A disease where goblet cells proliferate in a modified respiratory epithelium, leading to the accumulation of a mucin-rich effusion in the middle ear cleft. The MUC5AC and MUC5B mucin gene products have been identified as components of these effusions. To determine the effect of IL-6 and TNF-alpha on MUC5AC and MUC5B secretion we have used HT29-MTX goblet cells, which secrete both types of mucins. MUC5AC and MUC5B mucin secretion was measured by an enzyme-linked immunosorbent assay (ELISA) using a specific monoclonal antibody NCL-HGM-45M1 and polyclonal antiserum TEPA, respectively. Time response (0-72 hours) and dose response (1.5-150 ng/ml) studies were carried out. IL-6 and TNF-alpha stimulated MUC5AC and MUC5B mucin secretion in a time dependent manner, both in pre-confluent and post-confluent cells. IL-6 (15 ng/ml and 20 ng/ml) produced a low and prolonged stimulation of mucin secretion that persisted for 72 hours, with peak response at 24 hours after induction. The IL-6-mediated mucin secretion at 24 hours was concentration-dependent, with a maximal effect at 15 ng/ml. TNF-alpha (20 ng/ml) induced rapid stimulation of mucin secretion within the first 24 hours, with peak response at 7 hours after induction. IL-6 and TNF-alpha exposure significantly increased MUC5AC secretion, but not MUC5B secretion. Maximal levels of cytokine-induced mucin secretion were detected in pre-confluent cells that showed one and a half- and two-fold increases in MUC5AC secretion after IL-6 and TNF-alpha stimulation, respectively, in comparison with post-confluent cells. The results presented here suggest that IL-6 and TNF-alpha generate a differential up-regulation of mucin secretion and thus contribute to the expression of mucin genes in inflammatory responses.

Cell Division↗
PubMed2001

Reducing mucus production after urinary reconstruction: a prospective randomized trial.

PURPOSE: After transposition into the urinary tract, intestinal segments continue to produce mucus. We determine the effectiveness of muco-regulatory drugs, including N-acetylcysteine, aspirin and ranitidine, in reducing mucus secretion and urine viscosity in patients with transposed segments. MATERIALS AND METHODS: Our trial was a prospective randomized, double-blind placebo controlled crossover study involving 12 patients who underwent ileal conduit and 31 who underwent bladder reconstruction. Each treatment lasted 3 weeks with a 2-week washout. Pretreatment and posttreatment 24-hour urine samples were analyzed for mucin and viscosity after papain digestion, sodium dodecyl sulfate-polyacrylamide gel electrophoresis and periodic acid-Schiff assay. A disease specific questionnaire and SF-36 quality of life survey were completed. RESULTS: According to the questionnaire, mucus production did not decrease with time in 67% of patients. Mucin comprised 3% of the total nondialyzable material in urine (65 mg./24-hour for ileal conduit and 60 mg./24-hour for bladder reconstruction). Analysis of questionnaires and laboratory results failed to demonstrate any benefit of taking muco-regulatory agents compared with placebo. CONCLUSIONS: The use of N-acetylcysteine, aspirin and ranitidine did not result in a reduction in mucin production, urine viscosity or improvement in quality of life.

Acetylcysteine↗
PubMed2000

TNF-alpha in the regulation of MUC5AC secretion: some aspects of cytokine-induced mucin hypersecretion on the in vitro model.

TNF-alpha has been implicated in the aetiology of otitis media with effusion (OME), where goblet cells proliferate in a modified respiratory epithelium, leading to the accumulation of a mucin-rich effusion in the middle-ear cleft. The MUC5AC mucin gene product has been identified as a component of these effusions. Here we have used the HT29-MTX goblet cell line, which secretes MUC5AC mucin, as a model to study the effect of TNF-alpha on goblet cells. MUC5AC mucin was identified and quantitated with a monoclonal antibody NCL-HGM-45M1. TNF-alpha stimulates MUC5AC mucin secretion in a dose-dependent manner, with 20 ng/ml producing maximal stimulation. Both pre-confluent and confluent cells showed peak stimulation after 7 h, however the pre-confluent cells showed twice the level of mucin hypersecretion. These results suggest that TNF-alpha stimulation of mucin secretion could play an important role in the early acute phase of the development of OME. This hypersecretion of mucin could then lead to the failure of the mucociliary clearance system, resulting in the accumulation of a mucin-rich effusion in the middle ear and the movement to a more chronic phase of the disease.

Antibodies, Monoclonal↗
PubMed2000

The aetiology of otitis media with effusion: a review.

Otitis media with effusion (OME) is the most common cause of deafness in children in the developed world. In this article we aim to present an overview of current research developments on the aetiology of OME and the resulting implications for treatment. In the model we describe, the primary event is inflammation of the middle ear mucosa, usually due to the presence of bacteria. This leads to the release of inflammatory mediators, which cause secretion of a mucin-rich effusion by up-regulating mucin genes. Prolonged stimulation of the inflammatory response and poor mucociliary clearance lead to persistence of the middle ear fluid, giving rise to the clinical presentation of OME. We describe OME in the following sequence: the initial production of the effusion, the composition of the effusion produced, and factors impairing clearance of the effusion.

Humans↗
PubMed2000

Pseudomonas aeruginosa cell-to-cell signaling is required for virulence in a model of acute pulmonary infection.

Cell-to-cell signaling controls many virulence genes in Pseudomonas aeruginosa. We tested the virulence of las and rhl quorum-sensing mutants in neonatal mice. A lasI rhlI double mutant was nearly avirulent, and the respective single mutant strains were reduced in virulence compared with the wild-type strain. Quorum sensing plays a role in P. aeruginosa pneumonia in neonatal mice.

Animals↗