Hideki Miyaji

Helicobacter pylori infection occurs via close contact with infected individuals in early childhood

Background : The manner in which Helicobacter pylori is transmitted is of fundamental importance when considering strategies for its control, yet, to date, the exact mode of transmission remains uncertain.

Susceptibility of Helicobacter pylori isolates to metronidazole, clarithromycin and amoxycillin in vitro and in clinical treatment in Japan

Primary and acquired resistance to antibiotics is an important factor in determining the reason for treatment failure in Helicobacter pylori infection. We examined the relationship between the susceptibility of H. pylori isolates and the efficacy of chemotherapy.

Full-Length Sequence Analysis of the vacA Gene from Cytotoxic and Noncytotoxic Helicobacter pylori

Some clinical isolates of Helicobacter pylori fail to express vacuolating cytotoxin, despite possessing a copy of the vacA gene on the chromosome. To gain insight into the differences between vacA from cytotoxic and noncytotoxic strains, the vacA open-reading frames from 16 cytotoxic and 22 noncytotoxic strains were sequenced. Mutations that cause truncation of VacA in 11 of 22 noncytotoxic strains were identified, including internal duplication, large deletion, 1-bp insertion, and non-sense mutations. In contrast, none of the 16 cytotoxic strains had any truncation of VacA. Four cytotoxic strains had inserted sequences downstream of vacA. Three were mini-IS605, and the other was a putative rfaJ gene that encodes lipopolysaccharide glucosyltransferase. The rfaJ gene identified in this study had a poly(C) tract, resulting in premature termination of the gene product. The phylogenetic tree based on the vacA open-reading frame indicated that two different H. pylori lineages are circulating in Japan and the West.

Endoscopic [13C]-urea breath test for quantification of Helicobacter pylori infection

Background : We previously developed a new diagnostic method for Helicobacter pylori infection and called it the endoscopic [13C]‐urea breath test (EUBT). Here we evaluate the relationship between the EUBT results and the histological findings.

Effects of percutaneous endoscopic gastrostomy tube placement on gastric antral motility and gastric emptying

BackgroundPercutaneous endoscopic gastrostomy (PEG) is the preferred method for providing enteral nutritional support in patients with dysphagia. We examined gastric antral myoelectrical activity and gastric emptying before and after PEG tube placement to evaluate the effects of PEG on gastric motility.MethodsPEG was performed in 41 patients; 21 fed by total parenteral nutrition (TPN) and 20 who received nasogastric tube feeding (NGF). Antral myoelectrical activity and gastric emptying were examined before and 4 weeks after PEG tube placement.ResultsThe percentage of normal-range electrogastrograms (EGGs) was significantly lower in the TPN group than in the NGF group in both the pre- and postprandial periods before PEG tube placement. Enteral feeding after PEG tube placement improved gastric motility in the patients with TPN. The percentage of normal-range EGGs increased significantly after PEG tube placement in both the pre- and postprandial periods, and plasma concentrations of paracetamol increased significantly after PEG tube placement in patients with TPN. A total of 7.3% of the patients developed the complication of gastroesophageal reflux (GER) after PEG tube placement. Gastric myoelectrical activity and gastric emptying were improved in these patients with GER after PEG tube placement. In contrast, the prevalence of esophageal hiatus hernia was significantly higher in patients with GER after PEG tube placement than in patients without GER after PEG tube placement.ConclusionsProlonged TPN with bowel rest induces physiological dysfunction of gastric motility. Enteral nutrition is the preferable physiological nutritional route. GER after PEG tube placement is not related to gastric motility. Esophageal hiatus hernia seems to be a major risk factor for GER complications after PEG tube placement.

Bile Reflux due to Disturbed Gastric Movement Is a Cause of Spontaneous Gastric Ulcer in W/Wv Mice

Abstractc-Kit is a receptor tyrosine kinase, and it isencoded by the mouse W locus. Mutant W/Wvmice develop spontaneous gastric antral ulcers. The aimof the present study was to investigate the pathogenesis of these gastric ulcers and to examine theeffects of two antiulcer drugs; a proton pump inhibitor(2{[4-(3-methoxypropoxy)-3-methylpyridine-2-yl]methyl-sulfinyl}-1H-benzimidazole sodium salt, rabeprazole) and a mucosal protective drug(geranylgeranylacetone, GGA), on the gastric ulcers. Theinhibition of the gastric acid secretion by rabeprazole(30 mg/kg body weight, subcutaneous injection once a dayfor six weeks) significantly increased the gastriculcer formation compared to the controls. In contrast,the GGA treatment (100 mg/kg body weight, oraladministration for six weeks) significantly inhibited the ulcer formation. Bile reflux was seen inthese mutant mice, and they showed no cyclic intensecontractions in the gastric antrum. These resultssuggest that bile reflux due to the disturbance ofgastric antral movement is a cause of the spontaneousgastric ulcers in W/Wv mice.

Pharmacokinetics of clarithromycin in Helicobacter pylori eradication therapy in patients with liver cirrhosis

Background: Proton pump inhibitor triple therapy with clarithromycin and metronidazole has been widely used for Helicobacter pylori eradication. However, the efficacy and the safety of this therapy in patients with liver cirrhosis have not been established.

A Trial of 13C-urea Breath Test Combined with Endoscopic Phenol Red Test for Detection of Helicobacter pylori Infection

Abstract: Several tests for the diagnosis of Helicobacter pylori [H. pylori) infection have been employed in clinical studies. To minimize inaccuracies of these tests, we developed a new method which combines the 13C‐urea breath test (UBT) with phenol red dye spraying endoscopy. We have designated this innovation the endoscopic 13C‐urea breath test (EUBT). EUBT was conducted on 103 patients with gastroduodenal diseases. After the collection of a baseline breath sample, gastroduodenal endoscopy was performed. Twenty milliliters of 0.05% phenol red solution containing 100 milligrams of 13C‐urea was sprayed onto the entire gastric mucosa. A breath sample was collected 15 minutes after spraying. We measured 13CO2 in the breath samples by ratio mass spectrometry. Two biopsy specimens each from the antrum and the middle corpus were obtained for culture and histological examination. The mean EUBT values (±standard deviation) in H. pylori ‐positive and negative patients were 38.56±30.34%< and 0.19± 0.18%), respectively. The cut‐off value for EUBT was 0.73%. The sensitivity and specificity of EUBT were 100% and 95.5%, as compared with culture, and 100% and 95.5%, as compared with histological evaluation. The EUBT value of the patients with the diffuse staining type (50.28±31.26%) was significantly higher than that of patients with the regional staining type (26.76±23.17%). EUBT is an accurate method of detecting H. pylori infection and a good indicator of the distribution of the infection within the stomach.

Endoscopic Urease Sensor System for Detecting Helicobacter pylori on Gastric Wall Using a pH-sensitive Field Effect Transistor

An endoscopic tube‐tip type urease sensor was developed for the purpose of on‐site detection of Helicobacter pylori (H. pylori) using a pH‐sensitive field effect transistor (pH‐FET). The sensor is composed of an endoscopic‐tube connected to a feed pump with a urea solution and a pH‐FET attached to a sensor holder at the open end of the tube. The urease activity on the gastric wall can be measured by bringing the sensor into contact with the gastric wall just after replacing gastric juice with the urea solution. The presence of H. pylori causes a pH change in the urea solution inside the sensor holder in 20 seconds due to the strong urease activity of this bacterial species. After measurement, the sensor is detached from the wall, and washed with urea solution by turning on the urea pump. A measurement at one site is completed within 30 seconds. Repetition of the procedure makes multi‐site measurements possible. In preliminary evaluations, it was found that clinical sensitivity and specificity were 89% and 86%, respectively, using standard bacteriological testing results as a reference.