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At least 667 records · Page 37Linked to original sources
PubMed1991

Positive regulation of colonization factor antigen I (CFA/I) production by enterotoxigenic Escherichia coli producing the colonization factors CS5, CS6, CS7, CS17, PCFO9, PCFO159:H4 and PCFO166.

Entertoxigenic Escherichia coli (ETEC) strains of nineteen serogroups which produced colonization factors (coli-surface-associated antigens CS5, CS6, CS7 and CS17, colonization factor antigen CFA/III and putative colonization factors PCFO159:H4, PCFO166 and PCFO9) were tested for hybridization with a DNA probe containing the cfaD sequence that regulates expression of CFA/I. Strong colony hybridization, similar to that with the CFA/I-positive control strain H10407, occurred with ETEC strains of serogroups O27, O159 and O169 which produced CS6 antigen, and with all the strains which produced PCFO166 fimbriae. Weak colony hybridization, compared to the control strain, was found with ETEC producing CS5 fimbriae with CS6 antigen, CFA/III fimbriae with CS6 antigen, CS7 fimbriae or PCFO159:H4 fimbriae. CS6-antigen-positive strains of serogroups O79, O89 and O148 and all the CS17-antigen-positive and PCFO9-fimbriae-positive strains were negative in colony hybridization tests with the cfaD probe. Plasmid DNA of nine ETEC strains and their colonization-factor-negative derivatives was tested for hybridization with the cfaD probe and with ST and LT oligonucleotide probes. The sequences that hybridized with the cfaD probe were on the plasmids which coded for enterotoxin production. Fifteen strains were transformed with NTP513, a recombinant plasmid which contains the CFA/I region 1 fimbrial subunit operon but lacks a functional cfaD sequence, in order to determine whether DNA in any of these strains could substitute for the cfaD sequence in the regulation of production of CFA/I fimbriae.(ABSTRACT TRUNCATED AT 250 WORDS)

Agglutination Tests↗
PubMed1976

Colonization of porcine small intestine by Escherichia coli: ileal colonization and adhesion by pig enteropathogens that lack K88 antigen and by some acapsular mutants.

Seven K88-negative porcine enteropathogenic Escherichia coli, representing three different serogroups, caused severe diarrhea and characteristically colonized the ileum, but not the jejunum, of intragastrically exposed newborn pigs. Bacterial counts of intestinal contents and wall, fluorescence, and scanning electron microscopy all suggested that these strains colonized the ileum by adhesion to the villous epithelium. However, in ligated intestinal loops, these enteropathogenic E. coli strains adhered to jejunal epithelium as well as to ileal epithelium. Acapsular (K-) mutants, derived from one of the principal strains, retained their colonizing and adhesive abilities, whereas K- mutants from three other enteropathogenic E. coli strains did not. It is suggested that: (i) these K88-negative enteropathogenic E. coli colonize the ileum by adhesion, and (ii) the adhesion of some K-88-negative strains is mediated by surface factors other than, or in addition to, the polysaccharide K antigen.

Animals↗
PubMed1990

Roles of different coli surface antigens of colonization factor antigen II in colonization by and protective immunogenicity of enterotoxigenic Escherichia coli in rabbits.

The roles of the subcomponents of colonization factor antigen II, the coli surface antigens CS1, CS2, and CS3, as colonization factors and protective antigens was studied in a nonligated rabbit intestine model (RITARD). Infection with enterotoxigenic Escherichia coli (ETEC) carrying CS3 alone or CS1 plus CS3 induced diarrhea in most (80%) of the rabbits, whereas nonenterotoxigenic strains expressing CS1 or CS2 rarely induced diarrhea. Strains carrying CS1, CS2, or CS3 alone were all shed in stools for a significantly longer period than normal fecal flora-type E. coli. Initial infection with ETEC positive for CS1 plus CS3 induced significant protection against disease caused by reinfection with a highly diarrheagenic dose of the homologous strain; rabbits previously infected with serotype-heterologous, nontoxigenic bacteria carrying CS1 only were also protected against this challenge, whereas no such protection was induced by serogroup-homologous E. coli carrying CS2 only. Animals previously infected with CS1-, CS3-, or CS1-plus-CS3-positive bacteria excreted the CS1-plus-CS3 challenge strain for a significantly shorter period than did "nonimmunized" rabbits, whereas initial infection with bacteria carrying CS2 only did not result in such reduced shedding. Monoclonal antibodies against CS1, CS2, or CS3 all protected against experimental infection with ETEC carrying the corresponding CS factor. These results suggest that all the subcomponents of colonization factor antigen II are colonization factors and may induce anticolonization immunity.

Animals↗
PubMed2002

Acylation of the lipooligosaccharide of Haemophilus influenzae and colonization: an htrB mutation diminishes the colonization of human airway epithelial cells.

Haemophilus influenzae is a commensal and opportunistic pathogen of the human airways. A number of surface molecules contribute to colonization of the airways by H. influenzae, such as adhesins, including structures found in the lipooligosaccharide (LOS). A human bronchiolar xenograft model was employed to investigate the host-bacterial interactions involved in the colonization of the airway by H. influenzae. Differential display was used to identify H. influenzae mRNA that reflect genes which were preferentially expressed in the xenograft compared to growth. Eleven mRNA fragments had consistent increased expression when the bacteria grew in xenografts. On sequencing these fragments, eight open reading frames were identified. Three of these had no match in the NCBI or the TIGR database, while an additional three were homologous to genes involved in heme or iron acquisition and utilization: two of the mRNAs encoded proteins homologous to enzymes involved in LOS biosynthesis: a heptosyl transferase (rfaF) involved in the synthesis of the LOS core and a ketodeoxyoctonate phosphate-dependent acyltransferase (htrB) that performs one of the late acylation reactions in lipid A synthesis. Inoculation of human bronchiolar xenografts revealed a significant reduction in colonization capacity by htrB mutants. In vitro, htrB mutants elicited lesser degrees of cytoskeletal rearrangement and less stimulation of host cell signaling with 16HBE14o(-) cells and decreased intracellular survival. These results implicate acylation of H. influenzae lipid A as playing a key role in the organisms' colonization of the normal airway.

Acylation↗
PubMed2002

Colonic epithelial cells are a major site of macrophage inflammatory protein 3alpha (MIP-3alpha) production in normal colon and inflammatory bowel disease.

BACKGROUND AND AIM: Macrophage inflammatory protein 3alpha (MIP-3alpha) is a recently described lymphocyte directed C-C chemokine expressed predominately at extralymphoid sites, including the intestine. The aim of this study was to determine whether colonic epithelial cells produce MIP-3alpha and whether its expression is upregulated in inflammatory bowel disease. METHODS AND RESULTS: We found that interleukin 1beta and tumour necrosis factor alpha dose dependently stimulated MIP-3alpha production in Caco-2 and HT-29 intestinal epithelial cells. In cytokine treated Caco-2 and HT-29 cells, a significant increase in MIP-3alpha protein production was observed after three hours and continued for at least 24 hours. Analysis of colonic tissues by quantitative real time polymerase chain reaction and ELISA revealed significantly elevated MIP-3alpha mRNA levels (7.9-fold; p<0.05) and protein levels (8.9-fold; p<0.05) in Crohn's disease compared with controls or ulcerative colitis. MIP-3alpha immunoreactivity in normal colon and inflammatory bowel disease was principally associated with crypt and surface epithelial cells. Moreover, MIP-3alpha protein levels were elevated in primary epithelial cells isolated from patients with inflammatory bowel disease. CONCLUSIONS: These findings indicate that increased enterocyte MIP-3alpha production may play an important role in lymphocyte activation and recruitment to the colonic epithelium in Crohn's disease and ulcerative colitis.

Biomarkers↗
PubMed1991

Comparison of oral iodine-131-cellulose and indium-111-DTPA as tracers for colon transit scintigraphy: analysis by colon activity profiles.

In 11 normal subjects and 11 patients with a clinical diagnosis of constipation, oral 131I-cellulose and 111In-DTPA were compared simultaneously as tracers for radionuclide colon transit scintigraphy. Visual assessment of the images revealed no differences between tracers. Quantitation was performed using total and segmental percent retention and the derived value of clearance half-time. In addition, profiles of the activity distribution along the length of the colon were generated and the mean position of the activity in the colon calculated. For all indices, the results were similar in both normal subjects and constipated patients when comparing tracers, although marked differences were present between normal subjects and constipated patients for each tracer. Indium-111-DTPA was easy to administer and dosimetry was more acceptable than for 131I-cellulose, especially in constipated patients. It is concluded that 111In-DTPA is the preferred tracer for oral colon transit scintigraphy.

Administration, Oral↗
PubMed1988

Staphylococcus aureus at a maternity ward. I. Colonization of mothers and neonates and survival of various S. aureus types in colonized individuals.

Colonization by Staphylococcus aureus, characterized by phage type or production of enterotoxins and toxic-shock-syndrome-toxin, was followed in 50 mothers and their babies. Types or groups of staphylococci predominating during the particular period at the maternity department were evaluated according to survival rates in the colonized subjects. S. aureus frequently colonized nipples at the start of lactation and was found regularly on umbilical stump and in eye and mouth corners of the babies. During the second stage of the study phage untypable staphylococci producing enterotoxin C (NT/C) strongly predominated. These microorganisms colonized in the greatest extent both mothers and neonates. The majority of NT/C complex originated probably from one or two clones characterized, among others, by high biological activity.

Bacterial Toxins↗
PubMed1987

Chronic nonspecific inflammatory bowel disease of the cecum and proximal colon in children with grossly normal-appearing colonic mucosa: diagnosis by colonoscopic biopsies.

The diagnosis of inflammatory bowel disease rests on radiologic, endoscopic, and histologic criteria. Five patients, 2 to 17 years of age, sought medical attention because of chronic abdominal pain, diarrhea, and heme-positive stools. Rectal biopsies, visual inspection of colonic mucosa through the colonoscope, and contrast radiographs of the large and small intestine yielded nonspecific results. Serial endoscopic biopsies demonstrated a gradient of inflammatory changes diminishing in severity distally from the ileocecal valve and cecum. The disease process was most evident in specimens from the cecum, whereas biopsies distal to the transverse colon had a normal histologic appearance in all five patients. Biopsies from the proximal colon may provide evidence of inflammatory bowel disease not detectable using standard techniques. The combination of chronic abdominal pain, diarrhea, and heme-positive stools associated with inflammatory changes in biopsy specimens obtained from the proximal colon, but normal findings on radiologic, colonoscopic, and rectal biopsy examinations, may represent an early stage in the evolution of chronic nonspecific inflammatory bowel disease, including ulcerative colitis or regional enteritis (Crohn disease).

Adolescent↗
PubMed2000

Proteomic analysis of colonic crypts from normal, multiple intestinal neoplasia and p53-null mice: a comparison with colonic polyps.

In order to observe cellular changes caused by mutation of the tumor suppressors, APC and p53, we have generated protein expression profiles of mouse colon epithelial cells using two-dimensional electrophoresis (2-DE). Crypts, polyps and stroma were isolated from normal, multiple intestinal neoplasia (MIN) and p53-null mice, each with a C57Black/6J background, and subjected to 2-DE in two separate pH ranges (pH 3-10 and pH 6-11). No significant differences in protein expression patterns were observed between the normal, MIN and p53-null colon epithelial crypts. However, 64 proteins from the MIN polyps showed a 2-fold or greater difference in intensity that was statistically significant as assessed by the Wilcoxon rank-sum test (p < or = 0.05). Of these, calreticulin, carbonic anhydrase I and a new member of the glutathione-S-transferase theta family of proteins have so far been identified using an in-gel digestion protocol coupled with reversed-phase high performance liquid chromatography (RP-HPLC) ion-trap mass spectrometry. In addition, 38 marker proteins have been identified in a continuing effort to generate a comprehensive 2-DE database of proteins expressed by mouse colon epithelial cells (these databases are available at http://www.ludwig.edu.au/jpsl/jpslhome. html).

Animals↗
PubMed1983

The organization of intermediate filaments in normal human colonic epithelium and colonic carcinoma cells.

A comparative ultrastructural study of the organization of intermediate filaments (tonofilaments) within normal colonic epithelium and colonic carcinoma cells was carried out. The pattern of development of the specialized intermediate filament (IF) network, occurring during the differentiation of normal colonic epithelial cells, was examined to allow a more complete comparison with tumour cells of different degrees of differentiation. Essentially the IF system becomes more organized as the cells differentiate, resulting in the formation of a three-dimensional network loosely surrounding the nucleus, extending through the sub-terminal web and basal cytoplasm, and inserting into lateral desmosomes. Another system of IFs also runs directly between lateral desmosomes, lying parallel to the plasma-membrane and desmosomal plaque, without inserting directly into the junction. Alterations in the organization of the IF system were seen in tumour cells with the type and extent being dependent upon their location and degree of differentiation. Cells within areas of the tumour where some degree of glandular structure was retained exhibited major alterations in their microfilament-containing structures. However, their IF system was essentially intact and lateral desmosomes were still present in similar numbers to those seen in normal, partially differentiated mid-crypt cells. Apolar tumour cells within areas of the tumour where a gross loss of cryptal architecture had occurred exhibited a striking disorganization of their IF system. No parallel bundles of interdesmosomal tonofilaments were present beneath the cell surface and the majority of the three-dimensional network appeared to have collapsed around the nucleus, although some extensions to randomly distributed surface desmosomes still occurred. It appears that this disorganization of the IF system is associated with a loss of cell polarity and may involve alterations in putative IF-associated proteins important in the interaction of IFs with surface desmosomes or other cytoskeletal elements. A study of this phenomenon may shed light on both the means of IF organization and assembly and their role in normal cells as well as the possible role of alterations in cytoskeletal elements in the expression or maintenance of the malignant phenotype.

Carcinoma↗
PubMed1990

Colonic mucosal changes in nude mice associated with orthotopic xenografts of human colon cancer cells.

We used the nude mouse tumour xenograft model to study the pathogenesis of mucosa alterations in the large bowel surrounding a carcinoma. In mouse colonic mucosa overlying HT-29 colonic carcinoma xenografts in the caecum, the crypts were elongated in comparison with those in distant mucosa and also frequently showed a shift towards sialomucin production. These features, which are comparable with socalled transitional mucosa (TM) in man, were absent in control animals inoculated with Indian Ink instead of HT-29 cells. Although the localization of the proliferative cell compartment in mouse colonic mucosa overlying HT-29 xenografts appeared to be confined to the lower half of the crypt as in normal mucosa, the relative length of the DNA synthesizing cell compartment along the crypts was slightly elongated. These data strongly suggest that TM should be regarded as a secondary phenomenon rather than a premalignant change in large intestinal epithelium and that higher proliferative activity of epithelial cells contributes little to the elongation of crypts in TM.

Animals↗
PubMed1987

Colonic varices as a complication of colonic surgery.

Colonic varices are a rare cause of lower gastrointestinal bleeding, with approximately 40 cases reported in the literature. Portal hypertension is by far the most common cause of colonic varices, with local mesenteric vein obstruction constituting a very rare cause. We present a case of colonic varices not associated with portal hypertension but secondary to prior sigmoid resection and inferior mesenteric vein occlusion.

Angiography↗
PubMed1995

Diffuse colonic lipomatosis with giant hypertrophy of the epiploic appendices and diverticulosis of the colon. Report of a case and review of the literature.

PURPOSE: A case of diffuse colonic lipomatosis, dolichosigmoid, hypertrophy of the epiploic appendices and diverticulosis of the colon producing constipation, recurrent sub-occlusive episodes with diarrhea and vomiting, and weight loss is reported. METHODS: Careful preoperative assessment of clinical, radiologic, and endoscopic findings suggested the diagnosis. RESULTS: A total colectomy, followed by a lateroterminal ileoproctostomy, gave complete relief from symptoms. CONCLUSIONS: Of the 12 cases of colonic lipomatosis previously reported, only 2 have isolated involvement of the entire organ, but they do not present lipomatosis of the epiploic appendices.

Adult↗
PubMed1990

Normal human colon cells suppress malignancy when fused with colon cancer cells.

Normal human colon mucosa cells and cells obtained from histologically normal tissues near that cancer were fused with human colon cancer cells. Resultant hybrid populations of normal and malignant cell fusions behaved as nonmalignant cells in culture, were unable to grow in soft agar, did not express tumor-associated antigens, and were nontumorigenic in nude mice. Autofusion of the cancer cell population led to a phenotype intermediate between normal and malignant cells. That is, the cultures had a much lower plating efficiency in soft agar, and the tumors had a longer latency and slower growth rate in nude mice. This is the first cell culture system to demonstrate that normal epithelial cells can suppress malignancy of their autologous cancer cells, and is a prelude to more extensive studies of genetic events involved in malignant conversion of human colonic epithelium.

Animals↗
PubMed1989

Angiomyolipoma of the colon: a new entity in colonic polypoid lesions.

A 67-year-old man with angiomyolipoma on the sigmoid colon is reported. The colonic polyp was pedunculated and diagnosed histologically after endoscopic polypectomy. Angiomyolipoma is one of the benign hamartomas arising principally in the kidneys of patients with or without tuberous sclerosis. Extrarenal angiomyolipoma is rare and this may be the first report of colonic angiomyolipoma.

Aged↗
PubMed1991

Cancer associated antigen CA19-9 in colonic effluent of patients with neoplasia of the colon and inflammatory bowel disease.

We measured colonic effluent samples from 10 patients with colorectal cancer, 13 with adenomatous polyps, 14 with normal colons and compared them to 10 patients with inflammatory bowel disease by measuring this CA19-9 content. Results showed considerable overlap between the different pathologic categories, making differentiation impossible. A lower level of CA19-9 in the effluent samples from patients with adenomas was noted. These differences were reproducible for assays performed several months apart. CA19-9 may originate from the upper gastrointestinal tract since large amounts are present in pancreatico-biliary secretions. This antigen is therefore not useful in the diagnosis of neoplasia or inflammatory bowel disease using colonic effluent samples as the test material.

Adult↗
PubMed1998

Expression of G protein alpha subunits in normal rat colon and in azoxymethane-induced colonic neoplasms.

BACKGROUND & AIMS: Heterotrimeric G proteins are important in growth-regulating signal transduction. The aim of this study was to characterize the relative expression of G protein alpha subunits in rat colonocytes, colonocyte antipodal plasma membranes, and colonic neoplasms. METHODS: Antipodal plasma membranes were prepared from isolated colonocytes. Azoxymethane was administered to rats to induce colonic neoplasms. K-ras mutations in the neoplasms were determined by oligonucleotide hybridization and confirmed by primer mediated-restriction fragment length polymorphism. Colonocyte and tumor homogenates or membranes were probed for Galpha subunits by Western blotting with isoform-specific antibodies. RESULTS: The expressions of Galphai2, alphai3, and alphaq/11 were significantly enriched in the basolateral compared with brush border fraction of colonic antipodal plasma membranes. In neoplasms without K-ras mutations, the expression of Galphai2 increased 4-fold, Galphas(long) increased 2.5-fold, and Galphai3 increased 1.5-2-fold. Expression did not differ among tumor grades. K-ras mutations were associated with lowered expression of G proteins, especially Galphao. CONCLUSIONS: In colonocytes, Galpha subunits are localized primarily in basolateral plasma membranes. The increased expressions of Galphai2 and, to a lesser degree, Galphai3 and Galphas(long) in tumors was independent of tumor grade but was modulated by the presence of K-ras mutations.

Animals↗
PubMed2001

Oxygen free radical generating mechanisms in the colon: do the semiquinones of vitamin K play a role in the aetiology of colon cancer?

It is proposed that bile acids (deoxycholic acid), the K vitamins, iron(II) complexes and oxygen interact to induce an oncogenic effect in the colon by the generation of free radicals. In the relatively low oxidising/reducing conditions of the colonic lumen the K vitamins exist in the reduced form; however, if absorbed into the mucosa they have the capacity to be chemically oxidised and to enter into a redox cycle yielding oxygen radicals. The semiquinone radical of K(1) (phylloquinone) has been stabilised in bile acid mixed micelles and investigated by electron paramagnetic resonance spectroscopy and quantum chemical calculations. The estimated half-life of the radical was about 30 min which confirms a remarkably high stability in aqueous micellar solution. A model is presented in which the reduced K vitamins may initiate superoxide radical, O2(-*) generation leading to Fe(II) mediated Fenton reactions in the stem colon cells.

Bile Acids and Salts↗