The single-stage separation factors for boron isotopes between an ion-exchange resin and an external solution were determined, using an ion-exchange breakthrough operation. The lighter isotope boron-10 was considerably enriched in the anion-exchange resin phase. The separation factor was very much influenced by the boric acid concentration in the external solution, but not as much influenced by the kind of the anion exchange resin used and operation temperature. The separation factor increased with a decrease in the boric acid concentration of external solution from 1.008 (0.501 mol/l) to 1.016 (0.010 mol/l). The value of the separation factors obtained experimentally were compared with those estimated on the basis of the theory of the two-phase distribution of isotopes.

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The interaction of uranyl ion with acetic, glycolic, malic, tartaric, tricarballylic, and citric acids in aqueous solution has been investigated by means of IR and 13C NMR spectroscopy. The complex formation is reflected in the IR frequency shifts for the COO-stretching vibrations (yM(COO) and vs(COO)) and the asymmetric 0=U=0 stretching mode 03). The possible coordination structures of COO groups to the uranyl ion in the individual systems are discussed in terms of the IR frequencies of the vas(COO) and ys(COO) modes. The model calculation of the nas(COO) and vs(COO) frequencies based on a normal-coordinate treatment has indicated that the carboxylate coordination in the uranyl acetate and tricarballylate complexes is assigned to a bidentate structure in which both the two oxygen atoms in a given COO group take part in the coordination and that in the uranyl glycolate, lactate, malate, tartrate, and citrate complexes only one of the two oxygen atoms in a given carboxylate of the individual ligands coordinates to the uranyl ion. The carboxylate 13C NMR signals for all the systems examined have experienced significant shifts going from the individual free ligands to the complex species, which suggests the coordination of the carboxylate groups to the uranyl ion. Consideration of the alcoholic 13C NMR signals of the uranyl complexes involving glycolate, lactate, malate, tartrate, and citrate has indicated that the uranyl ion interacts with the alcoholic oxygen as well as the carboxylate oxygen of the individual ligands. The presence of some uranyl complex species, in which the alcoholic oxygen in a given -COH group coordinates to uranyl ion with dissociation of protons, was revealed by the observation of an unusually large lower magnetic field shift of the alcoholic carbon signal. The possible structures of the main uranyl complex species present in aqueous solution, compatible with the IR and 13C NMR evidence, are proposed and discussed.

Hypertension, nonsteroidal anti-inflammatory drugs, and anticoagulants, including aspirin, are independent risk factors for colonic diverticular hemorrhage.

The transparent hood was useful in shortening the cecal intubation time especially in difficult cases.

Background-The relationship betweenHelicobacter pylori and reflux oesophagitis remains controversial. Aims-To evaluate the relationship between H pylori and reflux oesophagitis in a large number of Japanese subjects. Subjects-A total of 5732 consecutive Japanese subjects during a health screening were enrolled. Methods-Gastrointestinal endoscopy was performed on all subjects. We simultaneously measured serum anti-H pylori antibody and pepsinogen as markers of H pylori infection together with gastric atrophy. The risk of reflux oesophagitis was evaluated in relation to these markers, and the results were compared with those of gastric cancer. Results-Reflux oesophagitis was found in 108 subjects. Both positivity for H pylori antibody (adjusted odds ratio (OR) 0.67 (95% confidence interval 0.45-1.0)) and "low" pepsinogen indicating gastric atrophy (OR 0.35 (0.18-0.68)) were negatively associated with reflux oesophagitis. After subjects were classified into four groups based on positivity or negativity for H pylori antibody and "low" pepsinogen, the prevalence of reflux oesophagitis showed a decreasing trend as H pylori induced gastric atrophy became more severe. The risk of gastric cancer showed an increasing trend, exactly the opposite to that of reflux oesophagitis. Conclusions-Analysis of a large series of Japanese subjects revealed a decreasing prevalence of reflux oesophagitis in conjunction with progress of gastric atrophy induced by H pylori infection. This pattern was completely opposite to that of gastric cancer cases. A protective role of H pylori for reflux oesophagitis through the development of gastric atrophy has been suggested.

Epidemiologically, the association between chronic Helicobacter pylori infection and development of gastric cancer is well established. Although the possibility of preventing gastric cancer by eradicating H. pylori infection was recently investigated by several research groups, the results remain controversial. The aim of this study was to determine whether the eradication of H. pylori infection would reduce the incidence of gastric cancer. In total, 304 patients with persistent H. pylori infection and 404 patients with H. pylori infection eradicated were examined annually for gastric cancer by endoscopy. Over an average of 3.1 years for the first group and 3.2 years for the second group, 13 and 6 patients, respectively, were diagnosed as having new gastric cancer. The cumulative incidence of gastric cancer was statistically different between the groups (P=0.019; log-rank test). The hazard ratio of H. pylori eradication was 0.335 by Cox proportional hazards model (P=0.047). Differentiated gastric cancer was found in 11 patients in the persistent infection group and 3 patients in the eradicated group. The incidence of differentiated cancer was significantly different (P=0.017) between the groups, but not for undifferentiated cancer (P=0.847). The results of the current study suggest that the eradication of H. pylori infection reduces the incidence of gastric cancer.

Background: Whereas high recurrence rates of colorectal adenomas after polypectomy are widely recognised, little is known of the natural incidence in those with no neoplastic lesions initially. It is also known that single colonoscopy has a significant miss rate. Aims: To elucidate the incidence and recurrence rates of colorectal neoplasms from a large cohort of asymptomatic Japanese patients on the basis of annually repeated colonoscopies. Methods: A total of 6225 subjects (4659 men and 1566 women) participating in an annual colonoscopic screening programme and completing three or more colonoscopies were analysed during the 14 year period between 1988 and 2002. Patients were divided into three groups according to the findings of the initial two colonoscopies: 4084 subjects with no neoplasm, 1818 with small adenomas ,10 mm, and 323 with advanced lesions, including carcinoma in situ, severe dysplasia, or large adenomas >10 mm. Mean age at the second colonoscopy was 48.8 years.Results: For all types of colorectal neoplasms, the incidence rate in those with no initial neoplasm was 7.2%/year whereas recurrence rates in those with small adenomas and advanced lesions were 19.3% and 22.9%/year, respectively. For advanced colorectal lesions, the incidence rate was 0.21%/year whereas recurrence rates in those with small adenomas and advanced lesions were 0.64% and 1.88%/year, respectively. Colorectal neoplasms were in general more likely to develop in males and older subjects. Conclusions: Although recurrence rates after polypectomy were elevated, the incidence rates in subjects with no neoplastic lesions initially were quite high.