Helicobacter pylori infection in two areas in Japan with different risks for gastric cancer.

BACKGROUND: We evaluated the relationship between Helicobacter pylori and various factors associated with gastric cancer in two areas in Japan with different risks for mortality due to gastric cancer. METHODS: A total of 250 sera from Niigata and 209 from Okinawa were used. H. pylori antibody and CagA antibody were measured by antigen-specific ELISAs. Serum gastrin and pepsinogen levels were determined by RIA. RESULTS: Although there was no significant difference in H. pylori prevalence among the persons in Niigata (50%) and Okinawa (42%), CagA prevalence in these populations was significantly different, at 41% and 26%, respectively (OR = 1.98, 95%CI: 1.33-2.95, P < 0.01). Serum gastrin levels in Niigata were significantly lower than those in Okinawa in H. pylori-negative persons (P < 0.01). The serum pepsinogen I/II ratio in Niigata was significantly lower than that in Okinawa in H. pylori positive persons (P < 0.01), whereas there was no significant difference in H. pylori-negative persons. Among those positive for H. pylori, serum pepsinogen I/II ratio in Niigata was significantly lower than that in Okinawa in CagA-negative persons (P < 0.01), whereas no significant difference was observed in CagA-positive persons. CONCLUSIONS: These results suggest that the difference in the mortality ratio of gastric cancer between Niigata and Okinawa is mainly associated with the difference between areas in the prevalence of cagA-positive strains rather than that of H. pylori itself.

Sequence analysis and clinical significance of the iceA gene from Helicobacter pylori strains in Japan.

The Helicobacter pylori iceA gene was recently identified as a genetic marker for the development of peptic ulcer in a Western population. To assess the significance of iceA subtypes of H. pylori in relation to peptic ulcer, 140 Japanese clinical isolates (88 from Fukui and 52 from Okinawa) were characterized. Sequence analysis of the iceA1 gene from 25 representative Japanese strains was also carried out to identify the differences in iceA between the ulcer group and the gastritis group. The iceA1 genotype was not correlated with the presence of peptic ulceration in either area. In addition, sequence analysis led to identification of five deletions and five point mutations (a nonsense mutation or a 1-bp insertion) within the iceA1 open reading frame corresponding to previously published sequences. These mutations were identified in both clinical groups (ulcer and gastritis groups) in each area. Local DNA sequence analysis revealed that the endpoints of all five deletions coincided with direct repeats. We also found four strains that carried longer iceA1 open reading frames compared with that for strain 60190. In conclusion, carriage of an iceA1 strain does not seem to be a risk factor for peptic ulcer in Japanese subjects. The critical mutations in the iceA1 gene in some isolates from patients with peptic ulcers suggested that IceA does not participate in the pathogenesis of peptic ulcer in Japan. We also found deletion hot spots that were associated with direct repeats in iceA1 and that favored a small-deletion model of slipped mispairing events during replication. We showed that iceA1 sequence variations may be useful tools for analysis of the population genetics of H. pylori.

[Analysis of the pathophysiology of H. pylori infection].

Vacuolating cytotoxin is an important virulence factor in H. pylori infection. Cytotoxin-producing H. pylori were more prevalent in patients with severe atrophic gastritis and cytotoxin activities in H. pylori isolates from patients with severe atrophic gastritis were much higher than those from patients with mild atrophic gastritis. It has also been suggested that there are host-related immunogenetic factors for susceptibility or resistance to diseases caused by H. pylori. The allele frequency of HLA-DQA1*0102 was significantly lower in the H. pylori(+) atrophic gastritis and H. pylori(+) intestinal type gastric adenocarcinoma than in the H. pylori(-) normal control and H. pylori(+) superficial gastritis. The HLA-DQA1*0102 allele may contribute to resistance against H. pylori-associated gastric atrophy and its association with intestinal type gastric adenocarcinoma.

A comparison of the binding characteristics of class I antiarrhythmic agents for human muscarinic m1-m3 receptors.

The binding characteristics of the class 1 antiarrhythmic agents, cibenzoline, disopyramide, disopyramide metabolite (the main active metabolite of disopyramide in humans), and pirmenol, for human muscarinic receptors (m1-m3) stably expressed in Chinese hamster ovary cells (CHO) were investigated by binding assay with [3H]N-methylscopolamine ([3H]NMS) as a ligand. All of these agents inhibited the specific [3H]NMS binding to membrane preparations in a concentration-dependent manner. The potencies of affinity of these agents for m1, m2, and m3 receptors (compared by IC50) were disopyramide > pirmenol > disopyramide metabolite > cibenzoline, pirmenol > cibenzoline > disopyramide > disopyramide metabolite, and disopyramide > disopyramide metabolite > pirmenol > cibenzoline, respectively. Some competition curves of cibenzoline, disopyramide, and pirmenol were shallow, and Hill coefficients of these curves differed from unity, suggesting that these agents have allosteric binding characteristics for human muscarinic receptors. The m2-selective ratios to m1 (IC50 m1/IC50 m2) and m3 (IC50 m3/IC50 m2) of cibenzoline were 4.0 and 16, and those of pirmenol were 6.5 and 43, respectively, whereas those of disopyramide and its metabolite ranged from 0.46 to 1.6, suggesting that cibenzoline and pirmenol exerted high selectivity to the m2 receptor. We conclude that (a) all class 1 antiarrhythmic agents in this study have inhibitory effects on human m1, m2, and m3 receptors, and some of those binding may show allosteric characterization; (b) disopyramide and its metabolite have similar affinity to m1 to m3 receptors; and (c) cibenzoline and pirmenol have high m2-selective ratios to m1 and m3.

Clinical features of patients with chronic liver disease associated with hepatitis C virus genotype 1a/I in Okinawa, Japan.

The clinical characteristics of chronic hepatitis C virus (HCV) carriers with HCV genotype 1a/I infection were investigated and compared with those of chronic HCV carriers infected with 1b/II, 2a/III, 2b/IV and the mixed type of infection. We found that 16 of 408 (3.9%) carriers had HCV genotype 1a infection, comprising four of 67 (6.0%) blood donors, 11 of 263 (4.2%) patients with chronic hepatitis and one of 39 (2.6%) patients with liver cirrhosis. Three of 408 subjects had a mixed infection of genotypes 1a/I and 1b/II. All carriers with genotype 1a (including those with the mixed infection) were of Japanese origin and all, except one who was born in Brazil, were born in Okinawa Prefecture. Nine of 14 patients infected with genotype 1a for whom medical records were obtained had a history suggestive of infection through blood exposure; six had had blood transfusions, one had tattoos, one is a nurse and one had a history of drug addiction. There were no haemophiliacs or other multitransfused patients in the genotype 1a group. Of 10 patients infected with genotype 1a who received interferon (IFN) therapy, four (40%) showed a complete response. Although the small number of patients infected with genotype 1a in the present study precluded statistical analysis of the response to IFN, the response in patients with genotype 1a was better than the response in those infected with genotype 1b and poorer than the response in those patients infected with genotype 2a/III or 2b/IV.

Profile of Helicobacter pylori cytotoxin derived from two areas of Japan with different prevalence of atrophic gastritis.

BACKGROUND AND AIM: To clarify the roles of Helicobacter pylori cytotoxin in gastric atrophy, the cytotoxin positive rate and cytotoxin activity in Fukui and Okinawa, where the prevalence of atrophic gastritis and gastric cancer risk are quite different, were studied. MATERIALS: Seventy three strains from Fukui and 51 from Okinawa were examined. METHODS: The validation of atrophy was done by endoscopy, being confirmed with histology. The supernatant of liquid H pylori culture media was concentrated 20-fold, serially diluted, using doubling dilutions, and scored from 1 to 8. The semi-quantitated cytotoxin activity was expressed as the maximum dilution score yielding > 50% A431 cell vacuolation, being standardised with bacterial density. RESULTS: The cytotoxin activity of the strains from Fukui was highly diverse compared with that from Okinawa, although the cytotoxin positive rate was not different. In Fukui strains, the grade of atrophy and the cytotoxin activity were correlated (p < 0.05). In addition, the cytotoxin activity of the strains from all patients in Okinawa, most of whom showed closed-type/mild atrophy, was significantly lower than that of the strains from the patients with open-type/severe atrophy in Fukui (6.46 (5.53) v 9.76 (8.80), p < 0.05), (mean (SEM)). CONCLUSION: The difference in profile of the cytotoxin activity in the two areas was related to the difference in the prevalence of atrophic gastritis.

Gene structural analysis and expression of human renal dipeptidase.

Human renal dipeptidase cDNA and genomic DNA were isolated from human kidney cDNA and genomic libraries, respectively. The human renal dipeptidase gene has a total length of approximately 6 kb and consists of ten exons and nine introns. The exons and cDNA each encode the 411 amino acid residues of the precursor protein, including 16 amino acid residues of signal sequence and a hydrophobic carboxyl terminal sequence for the attachment of a phosphatidylinositol glycan. Although the cDNA was slightly different from the cDNA reported by Adachi et al. (1990), the differences observed suggest, by comparison with human genomic DNA, that it may not represent an allelic variant but a cloning artifact. The recombinant human renal dipeptidase was produced on the surface of transfected L929 cells and had the same character as native renal dipeptidase. Northern blotting hybridization analysis showed that renal dipeptidase mRNA is only transcribed in kidney.

Purification and molecular cloning of mouse renal dipeptidase.

Mouse renal dipeptidase (mouseRDP, EC 3.4.13.11) was purified from the membrane fraction of kidney. The molecular mass of the enzyme was 115 kDa by size-exclusion HPLC and SDS-PAGE under non-reduced conditions and 58 kDa by SDS-PAGE under reduced conditions. The mouseRDP cDNA fragment was amplified from mouse kidney total RNA by reverse transcription-polymerase offin reaction (RT-PCR). The mouseRDP cDNA was isolated from a kidney cDNA library using the probe. The primary structure of mouseRDP deduced from the cDNA showed a high homology with renal dipeptidase from various mammals, except for the amino-terminal and carboxy-terminal domains. Recombinant mouseRDP obtained from transfected mouse L929 cells containing the expression plasmids has the same Km value and molecular mass as native mouse renal dipeptidase. From Northern blotting analysis, expression of the mouseRDP gene was recognized in both kidney and liver.

Significance of different conjugate forms of bilirubin in the formation of pigment gallstones.

The aim of the present study was to analyse bile samples from cases with gallstones by high performance liquid chromatography according to the type of stones present, with special reference to the glucoside and xyloside conjugates of bilirubin, and to investigate their deconjugation. The composition of bilirubin conjugates in bile was similar between cholesterol and black pigment stones except that the total bilirubin concentration was about 5 times higher in black pigment stone cases with haemolysis. Unconjugated bilirubin was higher in brown pigment stone cases than in cholesterol stone cases, although total bilirubin concentration was lower in the former. In addition, in brown pigment stone cases, bile contained statistically less bilirubin diglucuronide and more bilirubin diglucoside and monoglucoside than in bile with cholesterol stones (P less than 0.05). Glucoside and xyloside conjugates are also major components, regardless of the types of gallstones present, accounting for as much as 18 to 25%. Incubation experiment revealed that bilirubin diglucuronide was more readily deconjugated than bilirubin diglucoside or bilirubin monoglucoside monoxyloside. Therefore, glucuronide conjugates were likely to be the main source of unconjugated bilirubin in the formation of pigment gallstones.