Kyoji Seno

Increased intake of n-3 polyunsaturated fatty acids elevates the level of apoptosis in the normal sigmoid colon of patients polypectomized for adenomas/tumors

To clarify preventive effects of n-3 polyunsaturated fatty acids (PUFAs) against colorectal carcinogenesis, we performed a dietary intervention in patients polypectomized for colorectal adenomas/tumors. For the former the following dietary advice was given: (1) decrease intake of fat from 30 to 20% of the total; (2) decrease consumption of n-6PUFAs containing foods, and increase intake of n-3 PUFAs for 2 years. For the comparison group only decreased intake of fat (30-20%) was recommended. Samples of normal sigmoid colon mucosa, obtained by colonoscopic check once a year during the intervention period, were used to investigate COX-2, cell proliferation (Ki67 expression), p53, Bcl-2 and Bax by immunostaining and determine the apoptosis index (AI) by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-nick end labeling (TUNEL) in 21 and 20 patients in experimental and comparison groups, respectively, who completed the 2 years of the intervention. After 24 months, the AI and positive cells of Bax and the ratio of Bax/Bcl-2 in normal sigmoid colon mucosa for the experimental group was significantly increased, whereas this change was not found in comparison group. These observations demonstrated for the first time that increased intake of n-3 PUFAs promotes apoptosis of normal colon mucosa in human which is related to effect on Bax or the balance of Bax and Bcl-2.

Alpha-fetoprotein producing gastric cancer lacks transcription factor ATBF1.

Alpha-fetoprotein (AFP) producing gastric cancer (AFP–GC) is very malignant and highly metastatic compared with common gastric cancer. However, the causal relationship between AFP production and the high malignancy of AFP-GC is unclear. We investigated AFP gene regulation in AFP-GC by an active transcription factor, HNF1 (hapatocyte nuclear factor 1) and a repressive transcription factor, ATBF1 (AT motif binding factor 1). RNase protection assays revealed that the production of AFP in gastric cancer cells did not directly associate with HNF1 expression. An inverse relation between the expressions of ATBF1 and AFP was clearly observed in gastric cancer cells. CAT assays showed the direct inhibition of AFP gene expression by ATBF1. Methylation analysis of the AFP promoter region in gastric cancer cells suggested that methylation itself could not explain the silencing of the AFP gene. Immunohistochemistry of resected clinical samples revealed that AFP producing cells lacked ATBF1 immunoreactivity. Our data suggests that the absence of ATBF1 is responsible for AFP gene expression in gastric cancer, and the absence of ATBF1 is a distinct characteristic of AFP-GC and might be important for its highly malignant nature.

Immune responses in mice to intranasal and intracutaneous administration of a DNA vaccine encoding Helicobacter pylori-catalase

We previously reported that the intracutaneous injection of DNA vaccines encoding Helicobacter pylori heat shock proteins elicited specific immune responses, and led to reduced infection in mice. In this study, we constructed DNA vaccine encoding H. pylori-catalase (pcDNA3.1-kat) and investigated the immune responses to intranasal and intracutaneous administration of pcDNA3.1-kat. C57/BL6 mice were immunized intracutaneously with 10 microg of pcDNA3.1-kat or intranasally with 50 microg of pcDNA3.1-kat. Catalase-specific IgG antibody was detected in the sera of intranasal and intracutaneous immunized mice. Both intranasal and intracutaneous immunized mice were significantly protected from colonization by H. pylori and had significantly reduced degrees of gastritis. These results demonstrate that DNA vaccine encoding H. pylori-catalase can induce an immune response against H. pylori, and that intranasal immunization works as well as intracutaneous immunization.

The protective effect of rebamipide on paracellular permeability of rat gastric epithelial cells

Background : Barrier function in gastric epithelial cells is essential for the gastric defence mechanism against acid back‐diffusion into the mucosal layer. Our previous study indicated that trans‐epithelial resistance (TER) of rat gastric epithelial cells was rapidly increased when the cells were exposed to acid. This response to acid was diminished by indometacin.

Development and clinical application of an immunoassay using intact Helicobacter pylori attached to a solid phase as an antigen

OBJECTIVE At present, H. pylori homogenates, extracts and recombinant proteins are used as antigens in immunoassays, but significant false positive and negative results are obtained. We attempted to develop an ELISA system using immobilized whole intact H. pylori cells as a solid phase antigen (WIC-ELISA) which specifically recognizes surface antigens. METHODS Intact H. pylori cells were immobilized on ELISA plates by centrifugation (150 g for 10 min). HRP-labeled antihuman IgG was used as the second antibody. H. pylori-infections were investigated with WIC-ELISA and a conventional method in which H. pylori-extracts were used as antigen in 117 patients. RESULTS WIC-ELISA showed better characteristics than conventional ELISA in regards to sensitivity (98.9 vs. 90.4%), specificity (95.7 vs. 95.7%), positive predictive value (98.9 vs. 98.8%), negative predictive value (95.7 vs. 71.0%) and accuracy (98.3 vs. 91.5%). CONCLUSIONS WIC-ELISA is useful for quantification of antibodies against H. pylori surface antigens and as a clinical screening test.

Contribution of capsaicin-sensitive afferent nerves to rapid recovery from ethanol-induced gastric epithelial damage in rats.

Background and Aim:  It is well known that capsaicin‐sensitive nerve signaling acts as a protective factor against various ulcerogens. However, the contribution of topical capsaicin‐sensitive nerves within the stomach to rapid restitution has not been fully investigated. The present study was therefore conducted focusing on recovery from gastric mucosal damage induced by ethanol in vivo.

Complement plays an important role in gastric mucosal damage induced by ischemia-reperfusion in rats

Ischemia-reperfusion (I/R) of stomach causes gastric mucosal injury. Complement can also cause tissue damage, however its role in gastric I/R injury has not been thoroughly investigated. We evaluated the effect of complement suppression in reducing damage to the gastric epithelium caused by local I/R. Local gastric ischemia was induced by clamping the left gastric artery. The blood-to-lumen clearance of 51Cr-labeled EDTA (51Cr-EDTA) served as an index of epithelial damage. 51Cr-EDTA clearance increased shortly after reperfusion with peak values at 10 min. Intraperitoneal administration of cobra venom factor (CVF; 50 units) prior to I/R, which reduced the serum complement value (CH50) to an undetectable level, remarkably suppressed the 51Cr-EDTA clearance following reperfusion. A monocarboxylic acid derivative of K-76 (K-76 COOH) reduced the CH50 by more than 30% (100 mg/kg) and 60% (200 mg/kg). Rats pretreated with K-76 significantly attenuated the increase in 51Cr-EDTA clearance produced by I/R. These results suggest that complement inhibitor could be used to protect gastric mucosal injury induced by local I/R stress.

The Therapeutic Effect of Proton Pump Inhibitors on Helicobacter pylori-positive Gastric Ulcers

The aim of the present study was to elucidate the risk factors that could delay gastric ulcer healing when either a proton pump inhibitor or an H2‐receptor antagonist is used for gastric ulcer treatment.

Increased serum pepsinogen-I level predicts development of new duodenal erosion following eradication teraphy of H.pylori

Aims: Eradication of Helicobacter pylori (Hp) decreases the concentrations of serum gastrin (G) and pepsinogen (PG). However, the changes in serum level of such peptides during or just after eradication therapy have not been well investigated. In this study, we evaluated the changes in serum G and PG levels at the end of eradication therapy, and then investigated the relation to the duodenal erosion following eradication. Methods: We randomly treated 318 patients (104 female and 318 men, mean age 51 years) with abdominal symptom (109 gastric ulcer (GU), 113 duodenal ulcer (DU), 32 gastro-duodenal ulcer (GDU), and 64 atrophic gastritis (AG». Before eradication, endoscopy was performed and patients with duodenal erosion were excluded. One month after eradication, endoscopy was performed to check duodenal erosion, and Hip culture, histology, and urea breath test performed to assess Hip treatment. We determined G and PG level in sera at three time points: before eradication, at the end of eradication, and one month after eradication. Results: In 272 (85.5%) cured patients, 39 (14.3%) patients had new duodenal erosions. In 46 (14.5%) patients with unsuccessful treatment, no duodenal erosion appeared. Duodenal erosion developed in 27.3%, 10.7%, 9.1%, and 0% in the patients with DU, GDU, GU, and AG. The prevalence of duodenal erosion after Hip eradication was significantly higher (p < 0.005) in DU patients than in GU, and AG patients. In cured patients, G, PG-I, II, and IIII level one month after eradication were significantly decreased compared to those measured before eradication (p < 0.005). At the end of eradication, G and PG-I level were significantly higher than before eradication (p < 0.0001). In uncured patients, no changes were seen. In the patients with new duodenal erosions, G, PG-I, II, and IIII levels were similar to non-duodenal erosion patients before eradication and one month after eradication. However, at the end of eradication, only PG-I levels were significantly higher (p < 0.0001) than in the patients with non-duodenal erosion. Conclusions: 1. Successful Hip treatment causes a temporary high G and PG-I response at the end of eradication therapy. 2. Increased PG-I might be a kind of gastric mucosal response to H.p eradication since this temporary high level of serum PG-I is strongly associated with development of new erosions in duodenum. 3. These phenomenon strongly bring about duodenal mucosal damage by excess acid secretion and PG-I following eradication therapy.