The in vitro effect of ammonia on DNA synthesis in rat enterocytes

Zachrisson, Kristina; Midtvedt, Tore; Uribe, A.

doi:10.1097/00042737-199410000-00019

Cited by 6 publications

(8 citation statements)

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“…Thus, our results suggest that the stimulatory action of ammonia on DNA synthesis reported in experimental studies (4,9) is epiphenomal. The superficial mucosal damage induced by high concentrations of nonionized ammonia (NH3) may trigger a secondary trophic reaction in the proliferative zones to maintain the normal epithelial structure (32). As known, nonionized ammonia (NH3) is liposoluble, easily diffusible, and produces mucosal damage by inducing vacuolization and death of epithelial cells (11).…”

Section: Discussionmentioning

confidence: 99%

“…LS-123 cells (hmnan colonic adenocarcinoma cell line) and IEC-6 cells, a small intestinal cell line from germ-free rats (American Type Culture Collection, Rockville, MD) were propagated in 75-cIn z polystyrene cell culture flasks (Costar Europe Ltd., Badhoevedorp, Holland) in DMEM containing 5% fetal calf serum (screened for virus and mycoplasma) 10 gg bovine insulin per ml, 50 IU penicillin per ml, and 50 gg streptomycin per ml (enriched DMEM) (32). The cultures were kept in a water-saturated atmosphere with 5% CO2 at 37 ° C (Revco incubatm: Labora, Upplands V~isby, Sweden).…”

Section: Methodsmentioning

confidence: 99%

“…During the last 4 h, 1 gCi/ml [3H]methyl-thymidine specific activity (25 Ci/mmol) (Amersham Sweden AB, Solna, Sweden) was added to label cells in S-phase (32). After that, the medium was removed and the cells were rinsed with DMEM and fixed for 2 h at 4 ° C in 1 ml of a solution containing 3% glutaraldehyde, 0.1 M sodium eaeodylate, and 0.05 M sucrose, pH 7.3.…”

Section: Methodsmentioning

confidence: 99%

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Lipopolysaccharide of Escherichia coli, polyamines, and acetic acid stimulate cell proliferation in intestinal epithelial cells

Olaya

Neopikhanov

Uribe

1999

In Vitro Cell.Dev.Biol.-Animal

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Our aim was to examine whether lipopolysaccharide of Escherichia coli, polyamines of dietetic and/or bacterial origin, and products of the bacterial metabolism influence cell proliferation in epithelial cells from the colon and small intestine. Lipopolysaccharide of Escherichia coli 0111:B4 was incubated with cultures from human colonic mucosa. The mitoses were arrested with Vincristine and the total number of metaphases per crypt was counted. In addition, lipopolysaccharide was incubated with a human colonic epithelial cell line from adenocarcinoma (LS-123 cells) and with a nontransformed small intestinal cell line from germ-free rats (IEC-6 cells) for 24 h. In the last 4 h, the cells were labeled with tritiated thymidine. The cells were incubated with putrescine, cadaverine, and spermidine at 10(-11)-10(-3) M and with acetic acid (10(-5)-10(-1) M), acetaldehyde (10(-10)-10(-4) M) and ammonium chloride (1-20 mM). Lipopolysaccharide of Escherichia coli increased the number of arrested metaphases in human colonic crypts and DNA synthesis in L-123 and IEC-6 cells (P < 0.001). All polyamines increased DNA synthesis in the colonic and small intestinal cell lines, the effects being more marked for putrescine (P < 0.001). The higher concentrations of acetic acid increased DNA synthesis in both epithelial cell lines (P < 0.001). Acetaldehyde slightly decreased DNA synthesis in LS-123 cells at cytotoxic concentrations. Ammonium chloride did not significantly affect DNA synthesis. The final concentration of nonionized ammonia was less than 3%. It is concluded that lipopolysaccharides of Escherichia coli and intraluminal factors derived from microorganisms increase cell proliferation in human colonic crypts and intestinal epithelial cell lines.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Lipopolysaccharide of Escherichia coli, polyamines, and acetic acid stimulate cell proliferation in intestinal epithelial cells

Olaya

Neopikhanov

Uribe

1999

In Vitro Cell.Dev.Biol.-Animal

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“…The pH in the wells was determined just before termination of the incubation using a pH meter (PHM 82, Radiometer, Copenhagen, Denmark). The viability of the cells was estimated by excluding trypan blue, as described previously [20]. …”

Section: Microscopic Evaluationmentioning

confidence: 99%

Helicobacter pylori Stimulates DNA Synthesis in a Small Intestinal Cell Line in vitro

Brännström

Zachrisson²,

Hultén³

et al. 1998

Digestion

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Background: Helicobacter pylori, which causes gastritis and peptic ulcer, seems to be an important factor in the pathogenesis of gastric cancer and MALT lymphoma. Thus our aim was to examine whether H. pylori influences DNA synthesis in epithelial cells in vitro. Methods: Sonicated and water extracts of H. pylori (cytotoxic strains NCTC 11637, 88-23 and A5, and a noncytotoxic isogenic mutant of A5, A5 vac A) were diluted to a final concentration of 1/1,000, 1/100, 1/50 and 1/10. Water extracts of Escherichia coli were used as reference. IEC-6 cells were incubated during 24 h with fragments of H. pylori or extracts of the concentrations described above. The cells were labeled with ³H-methylthymidine for 4 h and processed for autoradiography. DNA synthesis was evaluated by the labeling index (LI). Results: The LI% of controls was 15.6 ± 5.1%. All the water extracts and sonicated strains of H. pylori increased the LI% in a dose-dependent manner (p < 0.001). The highest concentrations of the sonicated strains tended to reduce the LI%, although these values were still higher than those of the control group. The water extracts of E. coli increased the LI% in a dose-dependent manner (p < 0.0001). Conclusion: H. pylori stimulates DNA synthesis in epithelial cells in vitro, but no association was found with the presence of cytotoxin production. Our results suggest that hitherto unknown components of H. pylori may contribute to the increase in cell proliferation observed in gastritis and to the development of MALT lymphoma and gastric cancer.

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“…Thereafter, the cells were incubated for 24 h with the diluted bacterial fractions at concentrations described above or with DMEM only (negative control). One vCi/ml 3 H-Methyl-thymidine (specific activity 25 Ci/mmol, Amersham Sweden AB, Solna, Sweden) was added during the last 4 h to label cells in S-phase (11). Thereafter, the medium was removed and the cells were rinsed with DMEM and fixed for 2 h at + 4°C in 1 ml of a solution containing 3% glutaraldehyde, 0.1 M sodium cacodylate and 0.1 M sucrose, pH 7.3.…”

Section: Colonic Epithelial Cell Line: Dna Synthesismentioning

confidence: 99%

Mitogenic Factor(s) of Colonic Bacteria Stimulate DNA Synthesis in a Human Colonic Epithelial Cell Line

Olaya

1999

Microbial Ecology in Health and Disease

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Previous studies in 6itro show that intraluminal bacteria increase DNA synthesis in the intestinal epithelium. The aim of this study was to examine in 6itro whether supernatant solutions and various fractions of bacterial cells influence DNA synthesis in an epithelial cell line of human colon (LS 123). Methods: Strains of Gram-positive (Lactobacillus acidophilus and Lactobacillus fermentum)and Gram-negative bacteria (Escherichia coli K12 and Bacteroides thetaiotaomicron)were selected. In addition to supernatant solutions, bacterial cell fractions containing either cell wall/membranes, cytosol, nonsoluble intracellular components or dead bacteria were separated by means of multistep centrifugation, French press, and microfiltration. DNA synthesis (labelling index) was estimated on autoradiographs of LS-123 cells. These cells had previously been labelled with tritiated thymidine following incubation with different concentrations of the supernatant solutions and fractions described above (1/2000 -1/250). Results: The supernatant and all the fractions of E. coli significantly increased the labelling index in LS-123 cells (pB 0.0001). Only the highest concentration of the fraction of Bacteroides thetaiotaomicron containing whole bacterial cells increased the labelling index (p B0.001). The cytosolic fraction of Lactobacillus acidophilus significantly increased DNA synthesis at the higher dose range (pB 0.001). Conclusions: The microflora contains bacterial strains possessing hitherto unknown factor(s) that stimulate DNA synthesis in intestinal epithelial cells in 6itro. Our results suggest that at least the cell wall of E. coli K12 and the cytosol of the Gram-positive strain Lactobacillus acidophilus are sources of epithelial cell mitogen(s).

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The in vitro effect of ammonia on DNA synthesis in rat enterocytes

Cited by 6 publications

References 0 publications

Lipopolysaccharide of Escherichia coli, polyamines, and acetic acid stimulate cell proliferation in intestinal epithelial cells

Lipopolysaccharide of Escherichia coli, polyamines, and acetic acid stimulate cell proliferation in intestinal epithelial cells

Helicobacter pylori Stimulates DNA Synthesis in a Small Intestinal Cell Line in vitro

Mitogenic Factor(s) of Colonic Bacteria Stimulate DNA Synthesis in a Human Colonic Epithelial Cell Line

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