DNA Double Strand Breaks in Gastric Epithelium with Helicobacter pylori Infection / 대한소화기학회지

BACKGROUND/AIMS: DNA double strand breaks (DSB) is one of the critical types of DNA damage. If unrepaired, DSB is accumulated in the nucleus of cells, the cells become apoptotic or transform to tumor by way of genomic instability. Some of malignant cancers and its premalignant lesions were proven to have DSB in their nuclei. There was no report that Helicobacter pylori (H. pylori), the gastric carcinogen, induce DNA DSB in gastric epithelium in vivo. The aim of this study was to investigate whether H. pylori induce DSB in the gastric epithelial cells of chronic gastritis. METHODS: Immunohistochemical stains were performed for the DSB markers, phospho-53BP1 and gammaH2AX, in the gastric epithelium derived from 44 peptic ulcer disease patients before and after H. pylori eradication. DNA fragmentation assay was performed in the cell line to investigate the DNA damage by H. pylori infection. RESULTS: The mean expression score of gammaH2AX was significantly higher in the H. pylori infected gastric epithelium as compared to the H. pylori eradicated gastric epithelium (8.8+/-5.5 vs. 6.2+/-5.3 respectively; p=0.008). The expression score of phospho-53BP1 between before and after eradication of H. pylori was not statistically different, but tended to be higher in H. pylori infection. DNA fragmentation was developed significantly more in the cell lines after infection with H. pylori. CONCLUSIONS: DSB of DNA damage was typical feature of H. pylori infection in the gastric epithelium.

The Expression of Human beta-defensin 2 in Helicobacter pylori Infection

BACKGROUND/AIMS: Induction of human beta-defensin-2 (hBD2), an innate antimicrobial peptide in the intestinal mucosa, occurs after bacterial infections. The aim of this study is to evaluate the relationship between the expression of hBD2 and Helicobacter pylori (H. pylori) infection in the gastric epithelia. MATERIALS AND METHODS: Gastric mucosa was sampled from the patients with chronic gastritis and peptic ulcers before and after H. pylori eradication and the expression of hBD2 was assessed with immunohistochemistry. The antimicrobial effect was assayed as the number of colony forming units of H. pylori incubated with the various concentrations of hBD2. RESULTS: Thirty six patients were included in this study and 30 patients (83%) revealed expression of the hBD2 in their gastric epithelia. The hBD2 was not expressed in 22 patients after successful H. pylori eradication, but did expressed in 8 patients after H. pylori eradication failure. The expression of hBD2 was well correlated with the density of H. pylori, acute and chronic inflammation, and the degree of atrophy of gastric mucosa. CONCLUSIONS: The hBD2 is induced in the gastric epithelia in response to the H. pylori infection, and its expression is well correlated with the severity of gastric inflammation.

Double Strand Break of DNA in Gastric Adenoma and Adenocarcinoma / 대한소화기학회지

BACKGROUND/AIMS: DNA double strand break (DSB) is one of the critical types of DNA damage. When unrepaired DSB is accumulated in the nucleus of the cells having mutations in such genes as p53, it will lead to chromosomal instability and further more to mutation of tumor-activating genes resulting in tumorogenesis. Some of malignant cancers and its premalignant lesions were proven to have DSB in their nuclei. The aim of this study was to define the differences in expression of 53BP1 and gamma-H2AX, the markers of DSB, among normal, gastric adenoma, and gastric adenocarcinoma tissues. METHODS: Tissue microarray was made with the tissues taken from 121 patients who underwent gastrectomy for gastric adenocarcinoma, and 51 patients who underwent endoscopic mucosal resection for gastric adenoma. Immunochemical stain was performed for the marker of DSB, 53BP1 and gamma-H2AX in the tissue microarray. The normal tissues were collected from histologically confirmed tissues with no cellular atypia obtained from the patients with gastric adenocarcinoma. RESULTS: In gastric carcinoma cells, 53BP1 and gamma-H2AX were highly expressed as compared to normal epithelial cells and gastric adenoma (p<0.01). There were no differences in the expression of 53BP1 and gamma-H2AX between normal epithelium and gastric adenoma. The expression of 53BP1 in the adenoma with grade II and III atypism was more elevated than in those with grade I atypism. The expression of 53BP1 and gamma-H2AX were not significantly different according to the clinicopathologic parameters in the patients with gastric adenocarcinoma. CONCLUSIONS: The DSB in DNA seems to be associated with the development of gastric adenocarcinoma, but does not affect the premalignant adenoma cells.

IrreVersible Gel Tansformation of Injectavble Intraocular Lens by Photoinitiator and UV Irradiation in Rabbits

PURPOSE: This study was designed to induce irreVersible gel formation of poloxamer, the thermosensitive polymer hydrogel, by using photoinitiator and UV irradiation, and to verify the biocompatibility and usability of poloxamer as an injectable intraocular lens material through long-term observation in vivo. METHODS: Endocapsular phacoemulsification of lens was performed in rabbits and 25% poloxamer mixed with various concentrations of photoinitiator was injected into the capsular bag through a small capsulorhexis site. Then, the whole eye was irradiated with UV light for 5 minutes. The irreversibility and transparency of the post-operative poloxamer and the effects on the conjunctiva, cornea, iris, vitreous humor and retina were observed. RESULTS: As the results of this experiment using poloxamer 25% and photoinitiator 0.01%, the poloxamer remained transparent in the lens capsule for more than six months after the operation. No inflammatory response or toxicity was observed on the conjunctiva, cornea, iris, vitreous humor or retina. CONCLUSIONS: This study demonstrated the possibility of poloxamer as a new material for the injectable intraocular lens. Further study, however, is necessary.