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Naohito Shirai

Publications and source records attributed to Naohito Shirai.

11 recordsLinked to original sources
PubMed2004

Three-dimensional microarray compared with PCR-single-strand conformation polymorphism analysis/DNA sequencing for mutation analysis of K-ras codons 12 and 13.

BACKGROUND: We developed a rapid, precise, and accurate microarray-based method that uses a three-dimensional platform for detection of mutations. METHODS: We used the PamChip microarray to detect mutations in codons 12 and 13 of K-ras in 15 cell lines and 81 gastric or colorectal cancer tissues. Fluorescein isothiocyanate-labeled PCR products were analyzed with the microarray. We confirmed the microarray results with PCR-single-strand conformation polymorphism (SSCP) analysis and DNA sequencing. RESULTS: We could correctly identify wild-type, heterozygous, and homozygous mutant genotypes with the PamChip microarray in <3.5 h. The array data were consistent with those of PCR-SSCP analysis and DNA sequencing. All 15 cell lines and 80 of 81 clinical cancer specimens (98.8%; 95% confidence interval, 96.4-100%) were genotyped accurately with the microarray, a rate better than that of direct DNA sequencing (38.9%) or SSCP (93.8%). Only one clinical specimen was misdiagnosed as homozygous for the wild-type allele. Densitometric analysis of SSCP bands indicated that the content of the mutant allele in the specimen was approximately 16%. The PamChip microarray could detect mutant alleles representing more than 25% of the SSCP band proportions. Therefore, the limit for detection of mutant alleles by the PamChip microarray was estimated to be 16-25% of the total DNA. CONCLUSIONS: The PamChip microarray is a novel three-dimensional microarray system and can be used to analyze K-ras mutations quickly and accurately. The mutation detection rate was nearly 100% and was similar to that of PCR-SSCP together with sequencing analysis, but the microarray analysis was faster and easier.

Cell Line, Tumor↗
PubMed2004

Different dosage regimens of rabeprazole for nocturnal gastric acid inhibition in relation to cytochrome P450 2C19 genotype status.

OBJECTIVE: For the treatment of gastroesophageal reflux disease, intragastric pH should be lower than 4.0 for no more than 4 hours a day (<16.7%). We aimed to develop optimal dosage regimens for rabeprazole to control nocturnal acidity in relation to cytochrome P450 (CYP) 2C19 genotypes. METHODS: Fifteen Helicobacter pylori -negative volunteers, comprising 5 homozygous extensive metabolizers (EMs), 6 heterozygous EMs, and 4 poor metabolizers (PMs) of CYP2C19, took placebo and rabeprazole, at a dose of 20 or 40 mg once daily (at 10 pm ) for 8 days. Plasma rabeprazole concentrations and 24-hour intragastric pH were determined on days 7 and 8, respectively. Because the nocturnal intragastric pH was lower than 4.0 for more than 16.7% of the time with once-daily regimens in homozygous EMs and heterozygous EMs, they were administered 20 mg rabeprazole twice daily (8 am and 10 pm ) or 10 mg rabeprazole 4 times daily (8 am , 12:30 pm , 6 pm , and 10 pm ). RESULTS: With 40 mg rabeprazole once daily, the median percent time with nocturnal pH lower than 4.0 was less than 16.7% in PMs (9.5% [range, 3.0%-31.1%]) but not in homozygous EMs (45.3% [range, 29.0%-52.2%]) ( P = .043) and heterozygous EMs (41.3% [range, 33.0%-59.0%]) ( P = .043). The mean plasma rabeprazole concentrations differed among the different CYP2C19 genotype groups. With 20 mg rabeprazole twice daily and 10 mg rabeprazole 4 times daily, the median percent times with nocturnal pH lower than 4.0 were 5.0% (range, 0.0%-42.0%) and 1.0% (range, 5.0%-7.1%) in heterozygous EMs and 62.0% (range, 10.8%-68.3%) and 14.7% (range, 0.0%-41.7%) in homozygous EMs, respectively, and plasma concentrations were sustained longer than with the once-daily regimens. CONCLUSIONS: We propose that rabeprazole dosage regimens for sufficient acid inhibition are 20 mg once daily for PMs, 20 mg twice daily for heterozygous EMs, and 10 mg 4 times daily for homozygous EMs or heterozygous EMs.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed2004

Polymorphism of interleukin-1beta affects the eradication rates of Helicobacter pylori by triple therapy.

BACKGROUND AND AIMS: Polymorphism in interleukin-1beta (IL-1beta) is associated with intragastric pH levels in Helicobacter pylori-positive subjects. Intragastric pH levels affect the activity of antibiotics against H. pylori in the stomach. The aim of this study was to investigate whether IL-1beta polymorphism is associated with eradication rates of H. pylori by triple therapy with a proton pump inhibitor (PPI), amoxicillin, and clarithromycin. METHODS: Three hundred thirty-six patients infected with H. pylori completed treatment with omeprazole, 20 mg, or lansoprazole, 30 mg twice daily; clarithromycin, 200 mg 3 times daily; and amoxicillin, 500 mg 3 times daily, for 1 week. IL-1beta-511 and CYP2C19 genotypes of patients and sensitivity of H. pylori to clarithromycin and amoxicillin were determined. RESULTS: Logistic regression analysis showed that the IL-1beta-511 polymorphism, as well as CYP2C19 genotype of patients and clarithromycin-resistance of H. pylori, was associated with successful eradication. Eradication rates for H. pylori were 77.3% (75 of 97; 95% confidence interval, 67.5-84.6), 89.6% (147 of 164; 95% confidence interval, 83.9-93.1), and 94.7% (95% confidence interval, 86.9-98.5) in patients with the C/C, C/T, and T/T genotypes of IL-1beta-511, respectively (P = 0.0014). CONCLUSIONS: IL-1beta-511 polymorphism is one of the determinants of successful eradication of H. pylori using triple therapy with a PPI, amoxicillin, and clarithromycin, together with CYP2C19 genotype and bacterial resistance to clarithromycin.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed2004

Pharmacogenomics of proton pump inhibitors.

Proton pump inhibitors (PPIs), such as omeprazole, lansoprazole, rabeprazole, esomeprazole, and pantoprazole, are metabolized by cytochrome P450 isoenzyme 2C19 (CYP2C19) in the liver. There are genetic differences that affect the activity of this enzyme. The genotypes of CYP2C19 are classified into three groups: homozygous extensive metabolizer (homEM), heterozygous extensive metabolizer (hetEM), and poor metabolizer (PM). The pharmacokinetics and pharmacodynamics of PPIs differ among the different CYP2C19 genotype groups. Plasma PPI and intragastric pH levels during PPI treatment are the lowest in the homEM group and the highest in the PM group. These CYP2C19 genotype-dependent differences in pharmacokinetics and pharmacodynamics of PPIs are reflected in the cure rates for gastroesophageal reflux disease and Helicobacter pylori infection with PPI-based therapies. The CYP2C19 genotyping test is a useful tool for deciding on the optimal treatment regimen using a PPI, including a dual (PPI plus antibiotic) or a triple (PPI plus two antibiotics) therapy.

Anti-Bacterial Agents↗
PubMed2003

[Clinical significance of faecal calprotectin levels in patients with ulcerative colitis].

AIMS: To assess the clinical significance of faecal calprotectin levels (a neutrophil protein) in patients with ulcerative colitis (UC). METHODS: 25 patients with UC provided stool samples for calprotectin assay and the amount of calprotectin was related to UC disease activity index in each patient. Of 25 patients 4 with prednisolone refractory UC received 10 granulocyte and monocyte adsorption apheresis (GMCAP) sessions of 60 minutes duration, flow rate 30 mL per minute for 10 consecutive weeks. RESULTS: Calprotectin level in consecutive faecal samples from three patients was stable. However, increased calprotectin levels were significantly (p < 0.005) associated with Matts's endoscopic index, reflecting the level of colorectal inflammation. The 4 patients who received GMCAP therapy had a clinical activity index < 2 at week 7, the calprotectin level declined with improving Matts' index. CONCLUSIONS: Assay of faecal calprotectin holds promise as a sensitive biomarker to identify colorectal inflammation.

Adolescent↗
PubMed2002

Interleukin 1beta polymorphisms increase risk of hypochlorhydria and atrophic gastritis and reduce risk of duodenal ulcer recurrence in Japan.

BACKGROUND & AIMS: Interleukin-1 beta (IL-1beta) polymorphisms are associated with increased risk of gastric cancer in whites. This study aimed to examine effects of these polymorphisms on gastric acid secretion, atrophic gastritis, and risk of peptic ulcer in Japan. METHODS: We determined IL-1B-511/-31 and IL-1RN genotypes and measured gastric juice pH, serum pepsinogen (PG) I and II levels, and gastritis and atrophy scores in Helicobacter pylori-positive patients with gastritis only, gastric ulcers, or duodenal ulcers (DUs), and H. pylori-negative controls. RESULTS: In the H. pylori-positive group, subjects with the proinflammatory IL-1B-511 T/T genotype had the highest atrophy and gastritis scores, the highest median gastric juice pH, and the lowest median serum PG I/PG II ratios. Although gastric juice pH significantly increased and serum PG I and PG I/PG II ratios significantly decreased in the IL-1B-511 T/T genotype group with age, no such age-dependent changes were observed in the C/C genotype group. Changes in the C/T genotype group were intermediate. In the H. pylori-negative group, the IL-1 loci had no effect on any of the physiologic or morphologic parameters. Carriage of IL-1RN allele 2 significantly protected against DU disease while the IL-1B-511 T/T genotype significantly protected against DU recurrence in patients older than 60 years. CONCLUSIONS: Proinflammatory IL-1beta polymorphisms are associated with hypochlorhydria and atrophic gastritis in Japan. The effects are dependent on H. pylori infection and become more significant with advancing age. This may explain the high incidence of gastric cancer in Japan and also the age-dependent decrease in DU recurrence in infected subjects.

Achlorhydria↗
PubMed2002

Effect of cytochrome P4502C19 genotypic differences on cure rates for gastroesophageal reflux disease by lansoprazole.

BACKGROUND AND OBJECTIVES: The acid-inhibitory effect of lansoprazole depends on differences in cytochrome P450 (CYP) 2C19 genotypes. We assessed whether therapeutic effects of lansoprazole on gastroesophageal reflux disease (GERD) depended on the CYP2C19 genotype status in relation to the grade of GERD. METHODS: A total of 65 patients with GERD (grades A-D) completed treatment with lansoprazole, by taking 30 mg orally once a day for 8 weeks. The CYP2C19 genotype status of patients was determined by polymerase chain reaction-restriction fragment length polymorphism analysis. Before and after treatment, esophageal endoscopy was performed. GERD was considered to be cured on the basis of endoscopic findings at the end of treatment. Plasma lansoprazole levels could be determined at 3 hours after the last 30-mg dose of lansoprazole in the 27 genotyped patients. RESULTS: Cure rates for GERD depended significantly on the CYP2C19 genotype status, as well as the grade of GERD before treatment. Cure rates in the homozygous extensive, heterozygous extensive, and poor metabolizer groups were 45.8%, 67.9%, and 84.6%, respectively. Cure rates in the groups with GERD grade A, grade B, and grade C or D were 85.0%, 60.0%, and 45.0%, respectively. The cure rate in patients with the homozygous extensive metabolizer genotype of CYP2C19 with a GERD grade of C or D was very low (16.7%). Plasma lansoprazole levels in patients with the homozygous extensive metabolizer genotype were the lowest of the 3 groups. CONCLUSIONS: CYP2C19 genotype status, as well as the grade of GERD before treatment, is one of the determinants for the success or failure of treatment of GERD with lansoprazole. The low cure rate in patients with the homozygous extensive metabolizer genotype appeared to be a result of these patients having the lowest plasma lansoprazole levels among the 3 genotype groups.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMedDate not supplied

High-dose rabeprazole/amoxicillin therapy as the second-line regimen after failure to eradicate H. pylori by triple therapy with the usual doses of a proton pump inhibitor, clarithromycin and amoxicillin.

BACKGROUND/AIMS: Some patients are refractory to the usual triple therapy for eradication of Helicobacter pylori, consisting of a proton pump inhibitor, amoxicillin and clarithromycin, so there needs to be an alternative strategy for retreatment after failure to eradicate the infection. METHODOLOGY: The study group comprised 17 H. pylori-positive patients who had failed to clear H. pylori infection after 1 week of treatment with usual doses of proton pump inhibitor, amoxicillin and clarithromycin. The sensitivity of H. pylori to clarithromycin and amoxicillin, and the CYP2C19 genotype status of each patient were determined and treatment with rabeprazole (10 mg qid) and amoxicillin (500 mg qid) for 2 weeks was started. RESULTS: Eleven patients were infected with a clarithromycin-resistant strain of H. pylori. Twelve patients had the homozygous extensive metabolizer genotype, 5 had the heterozygous extensive metabolizer genotype and there were none with the poor metabolizer genotype of CYP2C19. All patients were successfully cleared of their H. pylori infection without any adverse effects, irrespective of CYP2C19 genotype status (100%, 95% confidence interval: 76-100%). CONCLUSIONS: High-dose dual therapy with rabeprazole (10 mg qid) and amoxicillin (500 mg qid) for 2 weeks appears useful treatment strategy after failure of eradication of H. pylori by the usual triple proton pump inhibitor/amoxicillin/clarithromycin therapy.

2-Pyridinylmethylsulfinylbenzimidazoles↗