Toshifumi Ohkusa

Promotion of colorectal neoplasia in experimental murine ulcerative colitis.

BACKGROUND: The mechanisms underlying the frequent development of colorectal carcinomas in patients with ulcerative colitis are still unknown. AIMS: To evaluate whether mucosal necrosis and regeneration act as enhancing or promoting factors in colorectal tumorigenesis, development of multiple colorectal tumours was studied in a murine model of ulcerative colitis with azoxymethane pretreatment. METHODS: Periods of chronic ulcerative colitis in mice were induced by three repeated administrations of 3% dextran sulphate sodium subsequent to a single azoxymethane pretreatment, to give conditions similar to the clinically observed active and remission phases. RESULTS: In the chronic colitis group with carcinogen exposure, multiple mucosal tumours (10.5/mouse) developed in the colorectum. This occurred primarily on the left side of the large intestine or transverse colon, the sites of the most severe colitic injury. The observed lesions were high grade dysplasias and invasive adenocarcinomas. Increased cell proliferation was evidenced by high uptake of bromodeoxyuridine, and increased activities of thymidylate synthetase and thymidine kinase. No tumours were induced in the control groups with azoxymethane pretreatment or chronic colitis alone. CONCLUSIONS: Repeated mucosal erosion with necrosis and regeneration is critical for the development of colorectal tumours in this experimental colitis system.

Induction of experimental ulcerative colitis by Fusobacterium varium isolated from colonic mucosa of patients with ulcerative colitis

Background: Bacteria are implicated in certain forms of model chronic colitis but the identity and role of bacteria in human ulcerative colitis (UC) are uncertain. Aims: To isolate pathogenic bacteria from inflamed mucosa of patients with UC, to examine whether the bacteria have a toxin to Vero cells, and to determine whether the toxin induces UC-like lesions in animals. Methods: Bacteria were isolated from UC patients and supernatants from cultures were filtered and tested for cytotoxicity to Vero cells. Bacterial cells producing the cytotoxic supernatants were examined by polymerase chain reaction for verotoxin genes. Culture supernatants of cytotoxic strains were examined by high performance liquid chromatography for organic acid concentrations. Mice were given enemas containing organic acid at the mean concentration in the supernatants of cytotoxic strains to ascertain whether colonic lesions appear in UC. Results: Only supernatants from cultures of Fusobacterium varium killed Vero cells. Bacterial cells lacked verotoxin genes. Bacterial culture supernatants contained high concentrations of n-butyric acid and the mean concentration (32 mmol/l) was cytotoxic to Vero cells. Twenty four hours after mice were given enemas containing either butyric acid or F varium culture supernatants, colonic ulcers with crypt abscesses, inflammatory cell infiltration, and apoptotic changes were observed. Conclusions: Butyric acid in culture supernatants from cultures of F varium caused UC-like lesions in mice. This study indicates that F varium may be one of the elusive pathogenic factors in UC.

Fusobacterium varium localized in the colonic mucosa of patients with ulcerative colitis stimulates species-specific antibody

Abstract Background: Microbial agents are a possible cause of ulcerative colitis. We have previously reported evidence of bacteria invading the colonic mucosa of patients with ulcerative colitis. We have isolated bacteria from inflamed colonic mucosa, examined the localization of the species in the mucosa, and assayed for serum antibodies to the bacteria.

Treatment of functional dyspepsia with antianxiety or antidepressive agents : systematic review

BackgroundThe pathophysiology of functional dyspepsia (FD) has not been elucidated precisely; accordingly, effective management of FD has not yet been found. Until now, treatment with antianxiety or antidepressive agents has been empirically applied; however, the efficacy of these treatments has not been established. We carried out this study to estimate the efficacy of these treatment approaches by systematically reviewing the literature concerning trials with agents that are efficacious against anxiety, neurosis, or depression.MethodsArticles were searched from the MEDLINE database up to October 2003, using the terms, “antianxiety agents”, “antidepressants”, and “dyspepsia”, and from reference lists of published articles. Finally, studies in which the effectiveness of drugs was clearly stated were selected from the retrieved articles.ResultsThirteen articles, on 1717 patients, were selected from among 90 articles retrieved through our literature search. In 11 of the 13 studies, dyspeptic symptoms were improved significantly by treatment. Statistical analysis of 4 trials showed a significant benefit of treatment with antianxiety or antidepressive agents (pooled relative risk, 0.55; 95% confidence interval [CI], 0.36–0.85), although funnel plots were asymmetric.ConclusionsAntianxiety or antidepressive agents may be effective in the treatment of FD patients, though further clinical trials are necessary.

Dysplasia and carcinoma development in a repeated dextran sulfate sodium-induced colitis model.

Background: As an important mechanism underlying the increased risk of colorectal carcinoma development in patients with long‐standing ulcerative colitis, promotion as a result of the regenerative process has been proposed. In the present study, a dysplasia‐carcinoma sequence in a novel repeated colitis model in mice is documented.

Oesophageal hypersensitivity in Japanese patients with non‐erosive gastro‐oesophageal reflux diseases

Background :u2002Visceral hypersensitivity plays a major role in the pathogenesis of non‐erosive oesophageal reflux disease (NERD). Prevalence of NERD differs according to the population and geographical region. Oesophageal hypersensitivity in NERD has not been well studied, especially in Japanese patients.

Occurrence of dysplasia and adenocarcinoma after experimental chronic ulcerative colitis in hamsters induced by dextran sulphate sodium.

In this study, long term dextran sulphate sodium administration was studied to ascertain whether colorectal carcinoma could be produced in patients with long standing ulcerative colitis. Simultaneously, changes in the intestinal microflora were analysed. Low grade to high grade dysplasia was seen in three of the five hamsters treated with 1% dextran sulphate sodium solution for 100 days, while no dysplasia was detected in the eight animals concomitantly treated with metronidazole, an antianerobic microbial agent, which prevents colonic ulceration. In these two groups, none of the animals developed colorectal cancer over 100 day period. In a group treated for 180 days, seven of the eight animals had dysplasia, and one had two adenomas. Furthermore, four of the eight animals had adenocarcinoma in the transverse colon; they were protruding well differentiated adenocarcinoma in one and non-protruding lesions infiltrating into the musclaris propria in three. The three non-protruding infiltrating adenocarcinomas were classified to be well differentiated adenocarcinoma in one and mucinous adenocarcinoma in two, resembling the type of cancer which complicates ulcerative colitis in man.

Alteration of histological gastritis after cure of Helicobacter pylori infection

Background : It is still disputed whether gastric atrophy or intestinal metaplasia improves after the cure of Helicobacter pylori infection.

Effectiveness of antibiotic combination therapy in patients with active ulcerative colitis: a randomized, controlled pilot trial with long-term follow-up.

Objective. It is proposed that Fusobacterium varium might be one of the elusive pathogenic factors in ulcerative colitis (UC). Our goal was to assess whether an antibiotic combination therapy against F. varium is effective for induction and maintenance of remission of UC. Material and methods. Twenty chronic, active UC patients with F. varium infection were enrolled consecutively and were randomly assigned to receive amoxicillin, tetracycline or metronidazole per os for 2 weeks (treatment group; n=10), or no antibiotics (control group; n=10). F. varium was sensitive to the antibiotics. Symptom assessment, endoscopic and histological evaluations were performed blind before enrollment at 3–5 months and 12–14 months after the treatment. Serum immunoglobulins to F. varium were measured using an enzyme-linked immunosorbent assay (ELISA). Immunohistochemical detection of F. varium in biopsy specimens was carried out using the avidin-biotin complex method. Results. The clinical activity, endoscopic and histological scores in the treatment group decreased significantly at 3–5 and 12–14 months after the end of treatment compared with those in the control group (p=0.001–0.036). The remission rate in the treatment group was higher than that in the control group (p=0.037). In addition, the titers of antibody to F. varium and the F. varium density in the mucosa decreased at both the short- and long-term follow-ups in the treatment group (p=0.0002–0.049). No serious drug-related toxicity was observed during the trial. Conclusions. The 2-week antibiotic combination therapy against F. varium was effective and safe in patients with chronic, active ulcerative colitis in this long-term follow-up study.

Altered localization and expression of tight-junction proteins in a rat model with chronic acid reflux esophagitis.

BackgroundThe esophageal tight junction is responsible for the paracellular sealing of the epithelium. Alteration of the expression of tight-junction proteins plays crucial roles in the pathogenesis of some human diseases. The aim of this study was to investigate the distribution and expression pattern of tight-junction proteins in the esophageal mucosa of control rats and rats with reflux esophagitis.MethodsChronic acid reflux esophagitis was experimentally induced by operation in rats. The animals were killed on days 7 and 14 after the operation. The thickness of the mucosa and the 5-bromo-2-deoxyuridine (BrdU) labeling index were assessed. The expression pattern of the tight-junction proteins claudin 1-4 and occludin in the esophageal mucosa was investigated by immunofluorescence staining and Western blotting in the controls and esophagitis rats.ResultsIn the esophagitis model, the thickness and BrdU labeling index increased with time. In control rats, claudin-1, -3, and -4 were localized on the cellular membranes of esophageal epithelial cells, mainly in the spinous and granular layers, while claudin-2 was not detected in any layer. Occludin was seen on the cellular membranes in all esophageal mucosal layers. In the esophagitis rats, the expression of claudin-1 was increased both in the plasma membrane and in the cytoplasm around the erosion in the spinous and granular layers. The expression of claudin-4 and occludin shifted to the cytoplasm from the plasma membrane in the spinous and granular layers. In contrast, the expression of claudin-3 was decreased in the spinous and granular layers.ConclusionsThe localization and the expression patterns of tight-junction proteins were different in the controls and the rat esophagitis model. The expression of claudin-3 in the esophageal mucosa was decreased, while that of claudin-1 was increased. It is postulated that these alterations in tight-junction proteins most likely increase the permeability of the esophageal the epithelium, thereby impairing the defense mechanism of this epithelium.