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Biomedical subjects

D R Mack

Publications and source records attributed to D R Mack.

At least 37 records · Page 2Linked to original sources
PubMed1995

Clinical denouement and mutation analysis of patients with cystic fibrosis undergoing liver transplantation for biliary cirrhosis.

OBJECTIVE: To describe the clinical characteristics of patients with cystic fibrosis considered for liver transplantation and the clinical outcome after transplantation. METHODS: Patient charts were reviewed. Mutation analysis was performed on blood or liver tissue samples with a panel of 17 mutations. RESULTS: Eight patients (five girls) with cystic fibrosis have undergone orthotopic liver transplantation for biliary cirrhosis. Mean age at transplantation was 12.0 years +/- 7.7 years (range, 9 months to 23 years). Preoperatively, seven patients had mild to moderate pulmonary dysfunction and one moderate to severe pulmonary dysfunction. All patients required pancreatic enzyme replacement, and four patients required insulin for diabetes mellitus. The 1-year survival rate was 75%, with no deaths related to septic events. Mean time of follow-up the six operative survivors was 4.1 years +/- 1.9 years. Pulmonary function testing, in those serially tested, showed that forced expiratory volume in 1 second was maintained or improved and that forced vital capacity improved after transplantation. Mutation analysis showed the following genotypes: four patients, delta F508/delta F508; one patient, delta F508/N1303K; and three patients, delta F508/unknown. CONCLUSIONS: Despite the high risk of transplantation, these encouraging results indicate that liver transplantation should be considered for patients with cystic fibrosis and complications of end-stage liver disease. We could not demonstrate an unusual pattern of CF gene mutations in these patients with severe liver disease. It appeared that immunosuppressive agents did not have a deleterious effect on pulmonary function.

Adolescent↗
PubMed1995

Intestinal mucin inhibits adhesion of human enteropathogenic Escherichia coli to HEp-2 cells.

Mucins are complex glycoproteins that cover the intestinal mucosal surface and are thought to provide protection against enteropathogenic infections by preventing bacterial adherence and subsequent colonization, invasion and toxin delivery. The aims of this study was to evaluate the capacity of intestinal mucin to inhibit epithelial cell adhesion by human enteropathogenic Escherichia colI (EPEC). EPEC strain E2348/69 (serotype O127:H6), known to produce a 94-kd epithelia cell-adhesion-mediating outer membrane protein called intimin and known to contain an EPEC adherence factor (EAF) plasmid, and three of its mutants were studied. Crude mucus was obtained from rabbit small-ubtestinal mucosal scrapings. Purified mucins were isolated by serial cesium chloride density gradient ultracentrifugation. Bacterial adhesion to HEp-2 epithelial cell monolayers in the presence of purified intestinal mucins was quantified by recovery of live viable bacteria as colony-forming units. EPEC strain E2348/69 adhesion was inhibited in a concentration-dependent manner by increasing amounts of mucin (adhesion suppressed to <1% by 150 microgram mucin). The relative magnitudes of inhibition of adhesion of E2348/69 and its mutants [JPN15 (EAF plasmid negative), JPN15.96(pMAR7) (intimin negative), and JPN15.96 (intimin negative, EAF plasmid negative)] were similar in the presence of equal amounts of mucin. The presence of the intimin protein and EAF plasmid are not necessary to the proficiency of mucin to inhibit HEp-2 epithelial cell adhesion.

Animals↗
PubMed1995

Disparate in vitro inhibition of adhesion of enteropathogenic Escherichia coli RDEC-1 by mucins isolated from various regions of the intestinal tract.

Escherichia coli RDEC-1 (serotype O15:H-) is a rabbit enteropathogen in which in vivo enteroadherence is both site specific and age related. To determine whether these differences could be related to mucins, we evaluated inhibition of binding of AF/R1 piliated RDEC-1 by mucins isolated from various segments of intestine of rabbits at different ages. Mucin was purified from intestinal crude mucus by cesium chloride serial ultracentrifugation. RDEC-1 was grown to promote the expression of hydrophobic mannose-resistant AF/R1 pili. Quantitation of in vitro bacterial binding was determined using a crystal violet colorimetric assay. In postweanling rabbits, inhibition of RDEC-1 binding by purified mucin derived from ileal segments (45.1 +/- 2.6%, mean +/- SEM) and proximal colonic segments (46.0 +/- 5.5%) was less than purified mucins derived from jejunal segments (70.0 +/- 2.0%) and distal colonic segments (71.0 +/- 3.7%, p < 0.05) of the intestinal tract. In all age groups, mucins derived from jejunal segments inhibited RDEC-1 binding to a greater level than mucins derived from ileal segments. In addition, inhibition of binding by mucin derived from proximal small intestine of postweanling rabbits (70.0 +/- 2.0%) was greater than that of weanling rabbits (55.2 +/- 3.5%, p < 0.05) with suckling rabbit inhibition (62.1 +/- 3.5%) between these two levels. We conclude that mucin inhibition of RDEC-1 adhesion is both age and region related and therefore may contribute to both age-related and site localization of bacterial infections of the intestinal tract.

Age Factors↗
PubMed1994

Expression of MUC1, MUC2, MUC3 and MUC4 mucin mRNAs in human pancreatic and intestinal tumor cell lines.

We examined the steady-state expression levels of mRNA for the MUC1, MUC2, MUC3 and MUC4 gene products in 12 pancreatic tumor cell lines, 6 colon tumor cell lines, and one ileocecal tumor cell line. The results showed that 10 of 12 pancreatic tumor cell lines expressed MUC1 mRNA and that 7 of these 12 lines also expressed relatively high levels of MUC4 mRNA. In contrast, MUC2 mRNA was expressed at only low levels and MUC3 was not detected in the pancreatic tumor cell lines. All 7 intestinal tumor cell lines examined expressed MUC2, and 5 of 7 expressed MUC3; however only one expressed significant levels of MUC1 and 2 expressed low levels of MUC4 mRNA. This report of high levels of MUC4 mRNA expression by pancreatic tumor cells raises the possibility that mucin carbohydrate epitopes defined by antibodies such as DuPan 2 may be expressed on a second mucin core protein produced by pancreatic tumor cells.

Base Sequence↗
PubMed1994

Alteration in expression of MUC2 and MUC3 mRNA levels in HT29 colonic carcinoma cells.

The cDNAs for two mucins, MUC2 and MUC3, have been derived from intestinal cells, however, the mechanisms that control expression of these genes are unknown. Steady-state mRNA levels for mucin gene products were examined in HT29 colonic carcinoma cells. Cells were grown in a conventional glucose medium and a glucose-free galactose medium to induce phenotypic differentiation. Northern blot analyses using cDNA probes of MUC2 and MUC3 were performed. MUC2 mRNA levels were decreased in cells grown in galactose medium compared to glucose medium whereas MUC3 mRNA levels were increased when cells were grown in galactose medium compared to those grown in galactose-free, glucose medium. This report shows steady state mucin gene expression is altered in HT29 cells grown in a medium that induces phenotypic differentiation and may provide a model for evaluation of induction of mucin gene expression.

Actins↗
PubMed1994

Surface hydrophobicity properties of rabbit stomach in vitro.

To quantitate surface hydrophobicity of the stomach, we measured contact angles formed with water droplets in different regions of rabbit stomach at varying ages (suckling, weanling, and adult). Contact angles were measured using novel methods: axisymmetric drop-shape analysis-contact diameter for contact angles < 90 degrees and axisymmetric drop-shape analysis-maximum diameter for contact angles > 90 degrees. To determine whether gastric mucus was responsible for the physical properties of the surface mucosa, the surface tension of mucus derived from the body of stomach was measured by axisymmetric drop-shape analysis on pendant drops. Contact angles of adult antrum 82.9 degrees +/- 5.5 degrees (mean +/- SEM) were greater than in the body of stomach (36.1 degrees +/- 2.6 degrees, p = 0.0001). Contact angles on mucosa obtained from the body of the stomach of both suckling rabbits (76.4 degrees +/- 2.7 degrees) and weanling rabbits (84.2 degrees +/- 2.9 degrees) were greater than in adult animals (ANOVA, p < 0.05). Pendant drop analysis of mucus derived from the body of stomach showed a high surface tension (57.72 +/- 0.06 mJ/m2, mean +/- SD). We conclude that there are maturational changes and regional differences in the surface hydrophobicity of the lapine stomach. These changes are likely caused by changes in the overlying mucus layer.

Animals↗
PubMed1993

Lack of inhibition of adhesion of an enteropathogenic Escherichia coli by polycarbophil.

Anionic polyacrylic acid polymers, such as polycarbophil, have a number of properties that would make them suitable carriers for sustained antibiotic release formulations in the intestinal tract. However, little is known with regards to possible microbial adhesion to polycarbophil. The aim of this study was to evaluate for such an interaction using the rabbit enteric pathogen Escherichia coli RDEC-1 (serotype O15:H-). RDEC-1 mediates attaching and effacing binding to intestinal epithelium in a manner morphologically identical to that observed in both human enteropathogenic E. coli and enterohemorrhagic E. coli infections. RDEC-1 bacteria were grown to promote the expression of the mannose-resistant AF/R1 adhesion pili. A nonpiliated mutant, strain M34, was used as a negative control. Using radioactive labeling of bacteria, we quantitated adhesion of piliated RDEC-1 in the presence of polycarbophil using an in vitro adhesion assay system. Binding of piliated RDEC-1 in the adhesion assay was greater than for nonpiliated M34 for all concentrations of bacteria greater than 10(9) (P < .05). Polycarbophil did not cause concentration-dependent inhibition of piliated RDEC-1 binding (P > .05). We conclude polycarbophil does not interfere with the AF/R1 adhesin ligand of RDEC-1. Use of this polymer as a mucoadhesive drug delivery vehicle for nonabsorbable antibiotics in the treatment of gastrointestinal infections would not be expected to interfere with the protective effects of intestinal mucins.

Acrylic Resins↗
PubMed1992

Systemic tumor necrosis factor-alpha production in experimental colitis.

Tumor necrosis factor-alpha (TNF) is a cytokine released by mononuclear cells in response to inflammation and sepsis. Since the biological effects of TNF are consistent with the systemic and intestinal features of ulcerative colitis, the role of TNF was examined in a rabbit model of chronic colitis. Peripheral blood mononuclear cells were isolated, stimulated with lipopolysaccharide, and cultured supernatants assayed for TNF levels using a cytotoxic assay on mouse fibrosarcoma L929 cells. Basal levels of TNF production by mononuclear cells from 13 normal rabbits (124.3 units/ml +/- 27.1 units/ml, mean +/- SE) were not different from nine rabbits with colitis (83.6 units/ml +/- 24.4 units/ml, P > 0.05). Treatment with lipopolysaccharide (100 micrograms/ml) induced increased TNF production by mononuclear cells isolated from both normals (672.0 units/ml +/- 197.5 units/ml, P < 0.05) and rabbits with colitis (1114.0 units/ml +/- 489.6 units/ml, P < 0.05). However, at all lipopolysaccharide concentrations stimulated TNF levels were comparable in experimental and control groups (P > 0.05). In light of the role of leukotrienes in inflammation, a separate group of rabbits with colitis was investigated following treatment with an oral leukotriene B4 receptor antagonist. Serum TNF levels in 15 control rabbits (32.5 units/ml +/- 7.6 units/ml, mean +/- SE) were not significantly different from rabbits with colitis receiving either leukotriene B4 receptor antagonist (35.7 units/ml +/- 9.2 units/ml, N = 13) or vehicle alone (50.3 units/ml +/- 10.2 units/ml, N = 14) (ANOVA, P > 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Correlation of intestinal lactulose permeability with exocrine pancreatic dysfunction.

Increased intestinal permeability to lactulose has been reported in patients with cystic fibrosis (CF). To determine whether this finding is unique to CF or whether it is related to accompanying exocrine pancreatic dysfunction, we evaluated 31 patients with CF and 10 with Shwachman syndrome who had variable degrees of pancreatic dysfunction, together with 17 healthy control subjects. There was no significant difference in the mean urinary lactulose excretion, expressed as the percentage of dose recovered, between CF and non-CF patients with pancreatic insufficiency (2.1% +/- 1.2% and 1.9% +/- 0.8, respectively) or between CF and non-CF patients with pancreatic sufficiency (0.6% +/- 0.5% and 0.6% +/- 0.3%, respectively). However, there was a significant difference in mean lactulose excretion between the pancreatic-insufficient and the pancreatic-sufficient patients (both CF and non-CF groups; p less than 0.001 and p less than 0.013, respectively). We further analyzed the results from 26 of the 41 patients (16 patients with CF and 10 non-CF patients) with pancreatic dysfunction who had previously undergone quantitative pancreatic function testing. A nonlinear, inverse relationship was found between urinary lactulose excretion and exocrine pancreatic function determined by duodenal trypsin output. These data confirm a direct relationship between intestinal lactulose permeability and the degree of exocrine pancreatic dysfunction, unrelated to the cause of the pancreatic disease.

Adolescent↗
PubMed1992

Surface hydrophobicity of the intestinal tract.

To quantitate surface hydrophobicity of the intestine, we measured contact angles formed with water droplets in multiple regions of rabbit intestine at varying ages (suckling, weanling, and adult) and after dinitrochlorobenzene-induced colitis. Contact angles were measured using novel methods: axisymmetric drop-shape analysis-contact diameter for contact angles less than 90 degrees and axisymmetric dropshape analysis-maximum diameter for contact angles greater than 90 degrees. To determine whether mucus was present on the surface of intestine used, indirect immunofluorescence was performed using antibody specific to goblet cell mucin. To confirm that intestinal mucus could be responsible for the physical properties of surface mucosa, surface tensions of mucus prepared from distal ileum, distal colon, and inflamed distal colon of adult rabbits were measured by axisymmetric drop-shape analysis on pendant drops. Contact angles of adult small intestine [duodenum, 38.0 +/- 11.2 degrees (SD); jejunum, 44.0 +/- 22.9 degrees; ileum, 56.4 +/- 23.3 degrees] were less than proximal colon (93.2 +/- 6.7 degrees; P less than 0.05) and distal colon (86.4 +/- 24.2 degrees; P less than 0.05). Contact angles on proximal colon from suckling rabbits (53.2 +/- 8.4 degrees) were less than both weanling (93.2 +/- 23.3 degrees; P less than 0.05) and adult rabbits (93.2 +/- 6.7 degrees; P less than 0.05). Contact angles on inflamed adult distal colon (54.7 +/- 20.6 degrees) were decreased from values on normal distal colons (86.4 +/- 24.2 degrees). Indirect immunofluorescence demonstrated that mucin was present in both vacuoles of goblet cells and on the colonic surface.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Effect of colonic inflammation on mucin inhibition of Escherichia coli RDEC-1 binding in vitro.

Intestinal mucus protects the underlying epithelium against adhesion and invasion by microbial pathogens and their products. In inflamed colonic mucosa there are both histochemical and biochemical changes in the major organic constituent of mucus, goblet cell-derived mucin. To determine if these changes result in differences in functional properties of mucin, inhibition of adherence of piliated Escherichia coli, strain RDEC-1 (serotype O15:H-), by mucin purified from distal colons of normal rabbits was compared with inhibition by mucin from colons of rabbits with dinitrochlorobenzene-induced colitis. Histology from inflamed colons revealed evidence of chronicity with a chronic inflammatory cell infiltrate, depletion of mucous glands, and branching of crypts. Mucin was purified from crude mucus of distal colonic mucosa by sequential ultracentrifugation and characterized by gel electrophoresis and amino acid analysis. The rabbit enteropathogen RDEC-1 was grown to promote expression of adherence pili. A nonpiliated mutant, strain M34, was used as a negative control. A concentration-dependent inhibition of piliated RDEC-1 binding was shown using mucins derived from both inflamed and noninflamed colons. However, equivalent dry weights of mucin purified from inflamed colons showed less inhibition of bacterial binding (10.3% inhibition +/- 5.2%; mean +/- SD) compared with mucin from normal colons (47.6% +/- 10.8%; P less than 0.05). Mucin purified from additional animals with hapten-induced colitis but treated with the oral leukotriene B4-receptor antagonist SC-41930 showed intermediate inhibition of RDEC-1 binding (35.6% +/- 14.3%). It is concluded that mucin derived from inflamed distal colon of rabbits failed to inhibit in vitro binding of piliated RDEC-1, and by decreasing mucosal inflammation, this functional alteration of mucin was partially reversed.

Animals↗
PubMed1991

Mucin isolated from rabbit colon inhibits in vitro binding of Escherichia coli RDEC-1.

The rabbit enteric pathogen Escherichia coli RDEC-1 (serotype O15:H-) mediates attaching and effacing binding to colonic epithelium in a manner morphologically identical to that observed in both human enteropathogenic E. coli and enterohemorrhagic E. coli infections. The aim of this study was to determine if colonic mucus and its constituents, including mucin derived from goblet cells, inhibited RDEC-1 adherence in vitro. Crude mucus was prepared from mucosal scrapings of rabbit colon and separated by buoyant density into eight fractions. Purified mucin was characterized by gel electrophoresis, dot immunoblotting, indirect immunofluorescence, and amino acid composition. RDEC-1 bacteria were grown to promote and suppress the expression of mannose-resistant, hydrophobic pili. A nonpiliated mutant, strain M34, was also used as a negative control. Binding of radiolabeled RDEC-1 expressing pili was quantitated in the presence of crude mucus, purified mucin, and nonmucin fractions. Binding of piliated RDEC-1 to hydrophobic polystyrene wells was greater than for both nonpiliated RDEC-1 and strain M34 (P less than 0.05). Both crude mucus and purified mucin mediated a concentration-dependent inhibition of piliated-RDEC-1 binding. Fractions of mucus without immunoreactive mucin did not inhibit the binding of RDEC-1 expressing hydrophobic pili. We conclude that colonic goblet cell-derived mucin mediates inhibition of piliated RDEC-1 attachment in vitro. Inhibition of bacterial adherence could prevent access of attaching and effacing E. coli enteric pathogens to the colonic mucosa in vivo.

Analysis of Variance↗