Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “colonization”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 793 records · Page 44Linked to original sources
PubMed1993

Influence of dietary calcium and vitamin D on colon epithelial cell proliferation and 1,2-dimethylhydrazine-induced colon carcinogenesis in rats fed high fat diets.

We investigated whether increased levels of dietary calcium and vitamin D could inhibit colon carcinogenesis in rats injected with a single dose of 1,2-dimethylhydrazine. Rats were given a single subcutaneous injection (200 mg/kg body wt) 2 wk before they were fed purified diets containing 20% fat for 32 wk. Diets contained one of three levels of calcium (5, 10 or 15 g/kg diet) as calcium gluconate and one of three levels of vitamin D (0.025, 0.05 or 0.1 mg/kg diet) as cholecalciferol in a 3 x 3 factorial design. Rats receiving the highest level of vitamin D had greater plasma concentrations of 25-hydroxy-vitamin D. Autoradiographic examination of [3H]thymidine-treated rats demonstrated that a higher dietary level of calcium as well as higher levels of vitamin D significantly affected cellular kinetic indices. The total tumor incidence and tumor incidence in the distal colon was 45% lower in rats fed the highest level of both calcium and vitamin D compared with the other eight groups, although this decrease was not statistically significant (P = 0.12). The possible importance of these observations is discussed.

1,2-Dimethylhydrazine↗
PubMed1984

Glycosaminoglycans of human colonic mucosa and colonic adenocarcinoma.

The mucosal scrapings of the normal human colons and the colonic adenocarcinoma tissues were digested with pronase, and the glycosaminoglycan fractions were prepared by fractionation with cetylpyridinium chloride after treatment with deoxyribonuclease. Chondroitin sulfate A/C, heparan sulfate, and hyaluronic acid were contained in the glycosaminoglycan fraction of the normal tissue, but dermatan sulfate was undetectable. In contrast, the glycosaminoglycan fractions derived from the tumors contained substantial amounts of dermatan sulfate together with the foregoing three glycosaminoglycans. The total content of glycosaminoglycans per wet tissue weight was elevated in the tumor tissues, which was consistent with histochemical findings.

Adenocarcinoma↗
PubMed1992

Colonic epithelial cell proliferation in a rat model of nongenotoxin-induced colonic neoplasia.

BACKGROUND: The effect on colonic cell proliferation of poligeenan, a nongenotoxic polysaccharide that induces colon tumors in rats, was compared with guar gum and carrageenan. EXPERIMENTAL DESIGN: Fischer 344 rats were fed a basal diet supplemented with carrageenan and poligeenan fibers for up to 91 days. The quantitative levels of proliferation, location of the proliferating cells, and the ability of the mucosa to readapt by removing the experimental fibers from the diet were tested. RESULTS: The mucosal epithelium exhibited a 5-fold increase in thymidine kinase activity in both the carrageenan and poligeenan groups. Proliferating cells appeared at the luminal surface only in the poligeenan-treated rats, and the number of proliferating cells in the upper third of the crypt increased 35-fold. A second and third set of animals were fed one of the three test diets for either 28 or 64 days, followed by a 28-day recovery period. Proliferation in the guar- and carrageenan-treated groups returned to basal levels. In poligeenan-treated rats, thymidine kinase levels, and proliferating cells in the upper third of the crypt remained 2- and 11-fold, respectively, above controls. CONCLUSIONS: The difference in recovery time between the poligeenan group and the others, and the luminal location of proliferating cells may prove useful as markers in understanding early events in the carcinogenic process induced by a nongenotoxin.

Administration, Oral↗
PubMedDate not supplied

Congenital segmental dilatation of colon with colonic atresia.

Congenital segmental dilatation of the colon belongs to a group of Hirschsprung's-like diseases with normal ganglion cells. The presentation is with chronic constipation affecting older children. We report a neonate with congenital segmental dilatation of the colon associated with sigmoid atresia. The child is well after a colostomy.

Colon, Sigmoid↗
PubMed1989

Malacoplakia of the colon in association with colonic adenocarcinoma.

We present two cases of malacoplakia of the colon in association with adenocarcinoma. The foci of malacoplakia characteristically comprised submucosal proliferations of histiocytes and chronic inflammatory cells with the typical cytoplasmic inclusions known as Michaelis-Gutmann bodies. These foci were found, respectively, adjacent to, and in contiguity with, a well- and moderately differentiated colonic adenocarcinoma. The possible pathogenetic relationship between these two processes is discussed.

Adenocarcinoma↗
PubMed1985

Submucosal colonic edema--urticaria of the colon.

Radiographically, colonic urticaria presents a non-specific pattern of submucosal edema. Previously unreported diverticulitis with colonic distention resulting in the flat, polygonal, mosaic pattern typical of this entity is described.

Colonic Diseases↗
PubMed1985

Cell surface glycopeptides from human intestinal epithelial cell lines derived from normal colon and colon adenocarcinomas.

The cell surface glycopeptides from an epithelial cell line (CCL 239) derived from normal human colon were compared with those from three cell lines (HCT-8R, HCT-15, and CaCo-2) derived independently from human colonic adenocarcinomas. Cells were incubated with D-[2-3H]mannose or L-[5,6-3H]fucose for 24 h and treated with trypsin to release cell surface components which were then digested exhaustively with Pronase and fractionated on Bio-Gel P-6 before and after treatment with endo-beta-N-acetylglucosaminidase H. The most noticeable difference between the labeled glycopeptides from the tumor and CCL 239 cells was the presence in the former of an endo-beta-N-acetylglucosaminidase H-resistant high molecular weight glycopeptide fraction which was eluted in the void volume of Bio-Gel P-6. This fraction was obtained with both labeled mannose and fucose as precursors. However, acid hydrolysis of this fraction obtained after incubation with [2-3H]mannose revealed that as much as 60-90% of the radioactivity was recovered as fucose. Analysis of the total glycopeptides (cell surface and cell pellet) obtained after incubation with [2-3H]mannose showed that from 40-45% of the radioactivity in the tumor cells and less than 10% of the radioactivity in the CCL 239 cells was recovered as fucose. After incubation of the HCT-8R cells with D-[1,6-3H]glucosamine and L-[1-14C]fucose, strong acid hydrolysis of the labeled glycopeptide fraction excluded from Bio-Gel P-6 produced 3H-labeled N-acetylglucosamine and N-acetylgalactosamine. This high molecular weight glycopeptide fraction was susceptible to mild alkaline borohydride reduction, yielding a mixture of labeled oligosaccharides which contained N-acetylgalactosaminitol. Thus, the HCT-8R cells are expressing fucosylated mucin-type glycoproteins on their surface.

Adenocarcinoma↗
PubMed1978

Glycoprotein synthesis and secretion in human colon cancers and normal colonic mucosa.

Glycoprotein synthesis and secretion were measured in short-term organ culture of normal and neoplastic colonic mucosa from 11 patients undergoing colectomy for colon cancer. Mucosal explants were incubated for up to 24 hr with [3H]glucosamine, which was incorporated into both explant and secreted glycoproteins. Structural and functional viability was documented by morphological studies that showed excellent preservation of architectural detail and biochemical studies that documented a steady increase in glycoprotein synthesis during 24-hr incubation. The major difference between normal and neoplastic mucosa was a 35% decrease (p less than 0.02) in the incorporation of [3H]glucosamine into tumor explants, as compared to the amount incorporated into normal explants from the same patient. The rate of secretion of radiolabeled glycoproteins into the medium did not differ significantly. Separation of explants into particulate and cytosol fractions showed that the overall decreases in glycoprotein synthesis in tumor explants was primarily due to a marked reduction in particulate glycoprotein synthesis in the cancer tissue.

Adenocarcinoma↗
PubMed1982

Morphogenesis of colonic carcinoma. Ultrastructural studies of azoxymethane-induced early lesions in colon epithelium of Fischer 344 rats.

Marked dilation and distortion of the crypts have been observed in the colonic epithelium of Fischer-344 rats after four to six weekly doses of azoxymethane (8 mg/kg). These changes precede malignant transformation in this model and, therefore, may be considered premalignant. Ultrastructural morphologic aspects of these crypts can arbitrarily be divided into three stages: an early stage of increased mucus secretion and "exhausted" appearance of mucous cells; an intermediate stage of severe crypt dilation, with extreme thinning of crypt epithelium and neutrophilic emigration to the mucous pool of the crypt lumen; and a late stage characterized by repopulation of the crypts, with epithelial cells showing an increased nuclear-cytoplasmic ratio and bizarre nuclei and nucleoli. The surface epithelium between the crypts shows increased cell loss and alterations of cell membrane. Similar structure of crypts has been described in the mucosa remote from carcinomas in rats and humans, and in various precancerous changes in humans (ie, ulcerative colitis and Crohn's disease). Therefore, I propose that these lesions are significant in human colon carcinogenesis as well.

Animals↗
PubMed1993

[Differentiation of human colon cancer cells: a new approach to cancer of the colon].

Our purpose is to demonstrate that some human colon cancer cells are able to express the same differentiation features as normal intestinal epithelial cells and to report experimental data which suggest that these particular cells are spontaneously resistant and adaptable to anticancer drugs. The concept of normal differentiation of colon cancer cells is supported by observations made with two cultured cell lines, Caco-2 and HT-29. The cell line Caco-2 expresses spontaneously and homogeneously an enterocytic differentiation. The cell line HT-29 is heterogeneous as it contains a small proportion (< 5%) of differentiated cells of either enterocytic or mucus-secreting type. Homogeneous populations of differentiated HT-29 cells of either type have been isolated by pressure selection. In order to investigate whether the pressure associated with anti-cancer drugs would result in the selection of differentiated populations, HT-29 cells were cultured in the presence of increasing concentrations of methotrexate and 5-fluorouracil. The resulting resistant populations were found to be totally differentiated. This supports the view that the small proportion of parental cells which are able to differentiate are also able to spontaneously resist to drug pressure. These results imply that the concept of cellular differentiation should be considered by pathologists. They also imply that basic research should be developed in order to unravel which mechanisms of drug resistance are specifically associated with the ability of the cells to differentiate.

Animals↗
PubMed1999

The effect of potassium diazoacetate on human peripheral lymphocytes, human adenocarcinoma Colon caco-2 cells, and rat primary colon cells in the comet assay.

In previous studies, N-(N'-acetyl-L-propyl)-N-nitrosoglycine (APNG) has been shown to be a potent mutagen in a variety of genotoxicity assays and a carcinogen in a limited cancer study. APNG decomposes to a carboxymethyldiazonium ion, which can also be generated from potassium diazoacetate (KDA). KDA is particularly interesting because it is a stable nitrosated derivative of glycine, one of the most common dietary amino acids. KDA has been shown to produce more O6 carboxymethyl- and O6 methyl-adducts than APNG, so it was anticipated that it might also be a potent genotoxic agent. Thus in the present study KDA has been investigated in the single cell gel electrophoresis (Comet) assay, which primarily measures DNA strand breakage. Since KDA has been shown to be formed in the gut, the genotoxic effects of KDA were investigated in vitro in human adenocarcinoma colon Caco-2 cells, and in rat primary colon cells and compared to responses from human peripheral lymphocytes. KDA induced DNA damage in the three cell types, confirming that KDA is genotoxic in a range of mammalian cells.

Adult↗
PubMed1982

Familial juvenile colonic polyposis with associated colon cancer.

A mother and son were found to have multiple juvenile polyps of the colon; later a metastatic adenocarcinoma of the large bowel developed in the mother. In both patients, histologic examination of the polyps did not reveal adenomas, but some of the juvenile polyps contained adenomatous-like elements. Because of the mother's history of colon cancer and the adenomatous features in some of the son's juvenile polyps, he underwent an elective subtotal colectomy. This family may represent a phenotype variation with features of both the juvenile and adenomatous polyposis syndromes and the presence of dysplasia of the glandular epithelium could be a marker of potential malignancy in patients with juvenile polyposis coli.

Adenocarcinoma↗
PubMed1993

Multidrug-resistant colonic cancer cell line LoVoDx is efficiently killed by lymphokine-activated killer cells from patients with carcinoma of the colon.

Multidrug-resistant (MDR+) cancer cells have the ability to grow in the presence of cytotoxic concentrations of antineoplastic drugs as a result of possessing the transmembrane drug efflux pump p-glycoprotein. The MDR+ colonic cancer cell line LoVoDx (derived from the drug-sensitive line LoVo) was tested for sensitivity to lymphokine-activated killer (LAK) cell-mediated toxicity. LAK cells were cultured from patients with colonic cancer and from matched controls with benign disorders. LAK cells from patients with cancer were as effective as those from controls in mediating cytotoxicity. The MDR+ cell line was significantly more sensitive to LAK cell-mediated cell killing than its parental drug-sensitive line LoVo (P < 0.05). These results indicate a possible role for adoptive immunotherapy in MDR+ tumours expressing p-glycoprotein.

Antineoplastic Agents↗
PubMed1993

[Differentiation of human colon cancer cells: a new approach to colon cancer].

Our purpose is to demonstrate that some human colon cancer cells are able to express the same differentiation features as normal intestinal epithelial cells and to report experimental data which suggest that these particular cells are spontaneously resistant and adaptable to anticancer drugs. The concept of normal differentiation of colon cancer cells is supported by observations made with two cultured cell lines, Caco-2 and HT-29. The cell line Caco-2 expresses spontaneously and homogeneously an enterocytic differentiation. The cell line HT-29 is heterogeneous as it contains a small proportion (< 5%) of differentiated cells of either enterocytic or mucus-secreting type. Homogeneous populations of differentiated HT-29 cells of either type have been isolated by pressure selection. In order to investigate whether the pressure associated with anti-cancer drugs would result in the selection of differentiated populations, HT-29 cells were cultured in the presence of increasing concentrations of methotrexate and 5-fluorouracil. The resulting resistant populations were found to be totally differentiated. This supports the view that the small proportion of parental cells which are able to differentiate are also able to spontaneously resist to drug pressure. These results imply that the concept of cellular differentiation should be considered by pathologists. They also imply that basic research should be developed in order to unravel which mechanisms of drug resistance are specifically associated with the ability of the cells to differentiate.

Cell Differentiation↗
PubMed1996

IL-4 and TNF-alpha induce changes in integrin expression and adhesive properties and decrease the lung-colonizing potential of HT-29 colon carcinoma cells.

The colon carcinoma cell line HT-29 was used to explore the potential of interleukin-4 (IL-4) and tumor necrosis factor alpha (TNF-alpha) to modify integrin expression and adhesive functions of tumor cells in vitro and to examine corresponding metastatic effects in vivo. Preincubation of HT-29 cells with 100 U/ml of IL-4 for 48 h downregulated the surface expression of the integrin subunits alpha 2, alpha 3, beta 1 and beta 4 after 48 h, whereas the alpha 1 subunit was upregulated. In contrast, 100 U/ml to TNF-alpha selectively upmodulated the expression of alpha v. Attachment to fibronectin of cells treated with IL-4 increased twofold (63.5% vs 32.4%). Adhesion to fibronectin (54.0% vs 32.4%) and vitronectin (37.9% vs 16.4%) was elevated in the case of TNF-alpha stimulation. Using an experimental metastasis model, HT-29 cells showed a significant reduction of their lung-colonizing potential in nude mice when preincubated with IL-4 for 48 h before intravenous injection. The decrease also observed for TNF-alpha-treated cells was less pronounced. The data indicate that the cytokines IL-4 and TNF-alpha can act as direct regulators of adhesive mechanisms of tumor cells bearing adequate receptors, thus influencing lung-colony formation.

Animals↗
PubMed1992

A scintigraphic analysis of colonic movement in patients with colostomy: changes of colonic transit time after acquaintance with irrigation.

For the purpose of making a functional assessment of colostomy irrigation, eight patients were examined. Group A was composed of four patients whose experience of irrigation was less than one year. Group B was composed of four patients who had undergone irrigation for more than two years. The capacity of the remnant colon was determined by a barium enema. Next, 74 MBq of milking technetium 99 diethylene triamine penta-acetic acid (99mTc-DTPA) was instilled with a predetermined amount of water (37 degrees C). A dynamic scan was performed for 45 min. The mean evacuation time of Groups A and B were 6 min 56 s +/- 2 min 33 s and 13 min 27 s +/- 10 min 50 s, respectively. The mean half emptying time of Groups A and B were 142.5 s +/- 7.9 s and 309.0 s +/- 181.9 s. The results suggest that the remnant colon may be habituated with irrigation. Colostomy irrigation which uses a single instillation of a measured volume of tepid water is recommended.

Adult↗