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Biomedical subjects

Toshifumi Hibi

Publications and source records attributed to Toshifumi Hibi.

At least 19 recordsLinked to original sources
PubMed2006

"Candidatus Helicobacter heilmannii" from a cynomolgus monkey induces gastric mucosa-associated lymphoid tissue lymphomas in C57BL/6 mice.

Both Helicobacter pylori and "Candidatus Helicobacter heilmannii" infections are associated with peptic ulcers, gastric adenocarcinoma, and gastric mucosa-associated lymphoid tissue (MALT) lymphomas. However, good animal models of H. pylori clinical diseases are rare. In this study, we aimed to establish an animal model of "Candidatus Helicobacter heilmannii" gastric MALT lymphoma. We used a urease-positive gastric mucosal and mucus homogenate from a cynomolgus monkey maintained in C57BL/6 mouse stomachs. The bacterium in the homogenate was identified as "Candidatus Helicobacter heilmannii" based on a DNA sequence analysis of the 16S rRNA and urease genes. Mucosal and mucus homogenates were used to inoculate C57BL/6 mice, which were then examined for 24 months. We observed a gradual increase in the surface area of protrusive lesions in almost all infected C57BL/6 mouse fundic stomachs 6 months after infection. Light microscopic observations revealed an accumulation of B lymphocytes along with destruction of glandular elements and the presence of lymphoepithelial lesions consistent with low-grade MALT lymphomas. Electron microscopic observation revealed numerous "Candidatus Helicobacter heilmannii" bacilli in the fundic glandular lumen, the intracellular canaliculi, and the cytoplasm of intact cells, as well as damaged parietal cells. In conclusion, "Candidatus Helicobacter heilmannii" induced gastric MALT lymphomas in almost 100% of infected C57BL/6 mice after a 6-month period associated with the destruction of parietal cells.

Animals↗
PubMed2006

Cytomegalovirus is frequently reactivated and disappears without antiviral agents in ulcerative colitis patients.

OBJECTIVE: The clinical significance of cytomegalovirus (CMV) reactivation complicating ulcerative colitis (UC) patients has been uncertain. It has therefore remained undetermined whether or not CMV reactivation should be treated in UC patients under immunosuppression. The aim of the study was to clarify the natural history of CMV reactivation in UC patients. METHODS: Sixty-nine UC patients with moderate to severe activity were enrolled in the study. All of the patients were treated with prednisolone, and/or immunosuppressants such as cyclosporine A. We sequentially monitored CMV reactivation every 2 wk up until 8 wk using the CMV antigenemia (Ag) assay and plasma quantitative real-time polymerase chain reaction (PCR) assay for CMV. RESULTS: Immunoglobulin (Ig) G for CMV was positive in 48 patients (69.6%) and negative in 21 patients (30.4%). CMV was reactivated in 25 patients out of the 48 seropositive patients (52.1%) during the study period. The CMV Ag and PCR values were low and none of the patients showed any evidence of CMV infection on biopsy specimens by hematoxylin and eosin staining. While gancylovir (GCV) was not used except in two patients, clinical outcomes including rates of remission and colectomy were not significantly different among the CMV reactivation-positive, -negative, and CMV IgG negative groups. Furthermore, CMV disappeared without GCV in most of the CMV reactivation-positive patients. CONCLUSIONS: CMV is frequently reactivated in active UC patients; however, it disappears without antiviral agents. Therefore, antiviral therapies should not be necessary for most UC patients with only CMV reactivation as long as CMV Ag values are low.

Adolescent↗
PubMed2006

Rapid detection of point mutations conferring resistance to fluoroquinolone in gyrA of Helicobacter pylori by allele-specific PCR.

Helicobacter pylori strains with reduced susceptibility to fluoroquinolones have a mutation at either codon 87 Asn or 91 Asp of the gyrA gene. A rapid test based on an allele-specific PCR (AS-PCR) was designed to detect the gyrA mutations. Clinical H. pylori isolates were obtained from the stomachs of 51 patients with H. pylori infections who showed treatment failure. The MICs of gatifloxacin (GAT) were determined by the agar dilution method. Identical genotyping results were obtained with AS-PCR and conventional PCR. The gyrA mutations of H. pylori causing reduced susceptibility to fluoroquinolones could be detected successfully by this method. A significant association was observed between the presence of mutations, as detected by AS-PCR, and the resistance of the strains to GAT. Moreover, genotyping by AS-PCR took less than 3 to 4 h. The AS-PCR method for the detection of gyrA mutations in H. pylori is useful for easy identification of fluoroquinolone-resistant strains of H. pylori.

Adult↗
PubMed2006

Effects of a Helicobacter pylori eradication regimen on anti-platelet autoantibody response in infected and uninfected patients with idiopathic thrombocytopenic purpura.

Thirty-seven patients with idiopathic thrombocytopenic purpura (ITP) were treated with a standard Helicobacter pylori eradication regimen irrespective of H. pylori infection. Our results indicate that platelet recovery results from the disappearance of H. pylori itself, and is mediated, in part, through suppression of anti-platelet autoantibody production.

Adult↗
PubMed2006

Melanosis and squamous cell neoplasms of the upper aerodigestive tract in Japanese alcoholic men.

Melanosis is frequently observed in the upper aerodigestive tract of Japanese alcoholic men, and the prevalences of squamous cell dysplasia and SCC in the upper aerodigestive tract of Japanese alcoholic men are high. This study evaluated associations between melanosis and both neoplasms of the upper aerodigestive tract and factors contributing to the development of melanosis in Japanese alcoholic men. Endoscopic screening of 643 Japanese alcoholic men (aged 50-79 years) was combined with oropharyngolaryngeal inspection and esophageal iodine staining, and ALDH2 genotyping was carried out in 425 of them. Melanosis was frequently (20.8%) observed in the upper aerodigestive tract. The palate was the most common site of melanosis (11.2%), followed by the pharynx (9.5%), and by the esophagus (7.0%). The incidence of melanosis was higher in those with esophageal dysplasia (31/126, 24.6%), esophageal SCC (19/42, 45.2%), and oropharyngolaryngeal SCC (8/14, 54.1%) than in cancer- and dysplasia-free controls (69/437, 15.8%). The presence of melanosis was associated with a higher risk of esophageal dysplasia, esophageal SCC, and oropharyngolaryngeal SCC (OR 1.69, 4.03, and 6.61, respectively). Multivariate analysis showed that older age, heavier smoking, and heterozygosity for inactive ALDH2 were positively associated with the presence of melanosis. The presence of melanosis indicates a high risk for neoplasms in the upper aerodigestive tract of Japanese alcoholic men. Melanosis and neoplasms have the same causes, including older age, heavy smoking, and high acetaldehyde exposure.

Aged↗
PubMed2006

p53 Protein accumulation, cancer multiplicity, and aldehyde dehydrogenase-2 genotype in Japanese alcoholic men with early esophageal squamous cell carcinoma.

Synchronous multiple intra-esophageal squamous cell carcinomas (SCCs) or oropharyngolaryngeal SCCs are common in alcoholics with esophageal SCC, and more frequently found in those with inactive heterozygous aldehyde dehydrogenase-2 (ALDH2). p53 alterations have been suspected as key molecular events in such multifocal esophageal carcinogenesis. We studied 95 Japanese alcoholic men with Tis and mucosal invasive esophageal SCC and found very high levels of p53 protein accumulation occurring in early esophageal SCC. Synchronous cancer multiplicity in the upper aerodigestive tract was found in 40 patients. p53 expression was not correlated with either cancer multiplicity or ALDH2 genotype. The risk for cancer multiplicity was associated with inactive heterozygous ALDH2 alone (OR=4.22) among the risk factors investigated, which also included smoking, less-active alcohol dehydrogenase-1B, and macrocytosis, enhancing the validity of the link between acetaldehyde exposure and cancer multiplicity.

Alcoholism↗
PubMed2006

Inhibition of neutrophil elastase prevents the development of murine dextran sulfate sodium-induced colitis.

BACKGROUND: Neutrophil elastase (NE) is a major secretory product from activated neutrophils and a major contributor to tissue destruction. However, little is known about the pathogenic contribution of NE to ulcerative colitis (UC). This study was designed to investigate the contribution of NE by measuring NE activity in plasma and colonic mucosal tissue from UC patients and a murine acute colitis model, and to elucidate the therapeutic effect of the NE-specific inhibitor ONO-5046. METHODS: The NE enzyme activities in plasma and colonic mucosal tissue from UC patients were directly measured using an enzyme-substrate reaction. Acute colitis was induced in mice by administration of 1.5% dextran sulfate sodium (DSS) for 5 days. DSS-induced colitis mice were then treated with ONO-5046 (50 mg/kg body weight) intraperitoneally twice a day. RESULTS: In UC patients, the NE enzyme activity was significantly elevated in both the plasma and colonic mucosal tissue compared with healthy controls. In DSS-induced colitis mice, the NE enzyme activity increased in parallel with the disease development. ONO-5046 showed therapeutic effects in DSS-treated mice by significantly reducing weight loss and histological score. ONO-5046 suppressed the NE enzyme activities in both plasma and culture supernatant of colonic mucosa from DSS-induced colitis mice. CONCLUSIONS: ONO-5046, a specific NE inhibitor, prevented the development of DSS-induced colitis in mice. NE therefore represents a promising target for the treatment of UC patients.

Adult↗
PubMed2006

Therapeutic strategies for functional dyspepsia and the introduction of the Rome III classification.

Although placebo response rates in clinical trials for functional dyspepsia (FD) are more than 30%, a recent meta-analysis based on randomized controlled trials (RCTs) showed that antisecretory drugs were more or less superior to placebos. On the other hand, large-scale RCTs on the efficacy of treatment with prokinetics on FD are still needed. Indications for antibiotic eradication therapy for Helicobacter pylori-positive FD are still controversial, but there seems to be a small but significant therapeutic gain achieved with H. pylori eradication. Since preprandial and postprandial symptomatic disturbances are very important targets for FD treatment, ghrelin, a novel appetite-promoting gastrointestinal peptide that also promotes gastric motility or basal acid secretion can be expected to be a therapeutic target. In the recently published Rome III classification, FD is redefined for patients with symptoms thought to originate from the gastroduodenal region, specifically epigastric pain or burning, postprandial fullness, or early satiation, and it is divided into the subcategories postprandial distress syndrome and epigastric pain syndrome. These new criteria are of value in clinical practice, for epidemiological, pathophysiological, and clinical research, and for the development of new therapeutic strategies.

Clinical Trials as Topic↗
PubMed2006

Acetaldehyde inhibits the formation of retinoic acid from retinal in the rat esophagus.

OBJECTIVE: It has already been demonstrated that the rat esophagus produces retinoic acid from retinol. In this study, this process is further characterized and the effect of acetaldehyde examined to elucidate the possible mechanisms behind the epidemiological evidence that the incidence of esophageal cancer is higher in alcoholics. MATERIAL AND METHODS: Rat esophageal samples were incubated with all-trans retinal and newly formed all-trans retinoic acid (ATRA) was quantified using high-performance liquid chromatography (HPLC). Furthermore, beta-nicotinamide adenine dinucleotide (NAD)-dependent acetaldehyde oxidation by the rat esophagus was examined by tracing NAD reduction using a spectrophotometer. RESULTS: Rat esophageal samples produced ATRA from all-trans retinal in a NAD-dependent manner and the potential was significantly attenuated by phenetyl isothiocynate, an ALDH inhibitor, or acetaldehyde depending on the concentration used. Rat esophageal samples also oxidized acetaldehyde of various concentrations NAD dependently. The ATRA formation potential that was temporarily inhibited by acetaldehyde was recovered to the control level by dialysis when the specimen was incubated with up to 50 microM of acetaldehyde. CONCLUSIONS: The rat esophagus produces retinoic acid from retinal. An ALDH isoform(s) is responsible for this process and physiological concentration of acetaldehyde hampers the process, probably in a competitive manner. Since the disturbance of retinoic acid supply has been implicated in carcinogenicity, this finding may, at least in part, explain the high incidence of esophageal cancer in alcoholics, especially in those with inactive ALDH 2 whose blood acetaldehyde levels become higher than those with active ALDH 2.

Acetaldehyde↗
PubMed2006

The endothelin-1 receptor-mediated pathway is not involved in the endothelin-1-induced defenestration of liver sinusoidal endothelial cells.

BACKGROUND/AIMS: We previously reported that endothelin (ET)-1 may be involved in the contraction of hepatic sinusoidal endothelial fenestrae (SEF). Rho has emerged as an important regulator of the actin cytoskeleton and consequently cell morphology. To clarify the role of ET receptors [endothelin A receptor (ETAR) and endothelin B receptor (ETBR)] in ET-1-induced defenestration, we studied the size of hepatic SEF under various experimental conditions. METHODS: Liver sinusoidal endothelial cells (LSECs) isolated from rat livers by collagenase perfusion were cultured and divided into four groups: control, ET-1 (10(-6) -10(-10) M)-treated, ET-1+selective ETAR antagonist (BQ610)-treated and ET-1+ETBR antagonist (BQ788)-treated groups. SEF morphology was observed by scanning electron microscopy. Protein expressions of ETAR and ETBR, Rho A and phosphorylated myosin light-chain kinase were analyzed by Western blotting. F-actin stress fiber formation was observed by confocal microscopy. Active Rho was measured by Ren's modification. Intracellular free Ca2+ concentration ([Ca2+]i) was measured by fluorescence digital imaging using fura-2 AM by Aqua cosmos. RESULTS: ET-1 induced a reduction in the number and size of SEF. ETAR antagonist pretreatment inhibited defenestration induced by low ET-1 concentrations (10(-8) -10(-10) M), whereas ETBR antagonist pretreatment did not block defenestration at low to high ET-1 concentrations (10(-6) -10(-10) M). F-actin stress fibers, Rho A levels and phosphorylated myosin light-chain kinase levels remained the same in various treatments. Active Rho was not detected in control and various treatments. ET-1 did not increase [Ca2+]i. Western blot showed prominent ETBR but scarce ETAR protein expression in LSECs. CONCLUSIONS: The present findings demonstrated that ETBR- and ETAR-induced contractile mechanisms are not involved in ET-1-induced defenestration, and that Rho is also not activated. Therefore, ET-1 induces hepatic defenestration by mechanisms other than receptor-mediated contraction.

Actins↗
PubMed2006

Role of erythrocytes as a reservoir for ribavirin and relationship with adverse reactions in the early phase of interferon combination therapy for chronic hepatitis C virus infections.

We investigated the relationship between serum ribavirin concentrations and clearance, as well as therapeutic efficacy and adverse reactions, in 97 Japanese patients with chronic hepatitis C virus infections treated with a 6-month course of high-dose alpha2b interferon (6 million units/day) plus ribavirin (600 to 800 mg/day) combination therapy. This randomized trial showed that the saturation of ribavirin uptake after taking ribavirin capsules does not occur within a dose range of 600 to 800 mg/day, which is a standard dosage used clinically in Japan. Serum ribavirin concentrations and clearance did not correlate with sustained virological response rates. Fourteen patients discontinued therapy because of adverse reactions, and sustained virological response rates were significantly reduced by discontinuation of therapy, while dose reduction of ribavirin did not alter the therapeutic effects. Ribavirin concentrations after 1 week and ribavirin clearance were significantly correlated with discontinuation of ribavirin; however, a multiple-regression analysis revealed that only hemoglobin concentration, but not ribavirin clearance, was a significant factor for discontinuation of therapy (odds ratio, 0.514; 95% confidence interval, 0.311 to 0.85; P = 0.0095). It appears that peripheral erythrocytes may act as a reservoir for ribavirin and regulate serum ribavirin levels in the very early phase of treatment.

Adult↗
PubMed2006

Risk of squamous cell carcinoma of the upper aerodigestive tract in cancer-free alcoholic Japanese men: an endoscopic follow-up study.

Asian case-control studies have shown a strong relationship between the development of squamous cell carcinoma (SCC) of the esophagus and alcohol consumption combined with inactive aldehyde dehydrogenase-2 (ALDH2*1/*2), less-active alcohol dehydrogenase-1B (ADH1B*1/*1), high mean corpuscular volume (MCV), and self-reported facial flushing in response to alcohol. However, little is known about whether these risk factors prospectively influence cancer development in cancer-free alcoholics. Between 1993 and 2005, 808 Japanese alcoholic men diagnosed as cancer-free by an initial endoscopic screening examination received follow-up examinations ranging from 1 to 148 months (median, 31 months) later, and SCC of the upper aerodigestive tract was diagnosed in 53 of them (esophagus in 33 and oropharyngolarynx in 30). Cox proportional hazards analysis showed that the age-adjusted relative hazard for SCC was 11.55 [95% confidence interval (95% CI), 5.73-23.3] in ALDH2*1/*2 heterozygotes compared with ALDH2*1/*1 homozygotes, 2.02 (95% CI, 1.02-4.02) in ADH1B*1/*1 homozygotes compared with ADH1B*1/*2 heterozygotes or *2/*2 homozygotes, 2.64 (95% CI, 1.49-4.67) in patients with flushing compared with those who had never experienced flushing, 2.91 (95% CI, 1.63-5.20) in those with an MCV >or= 106 compared with those with an MCV < 106, 2.52 (95% CI, 1.22-5.22) in those who smoked >or=30 cigarettes per day compared with those who smoked 0 to 19 cigarettes per day, 7.26 (95% CI, 3.99-13.23) in those with esophageal dysplasia compared with those without distinct iodine-unstained lesions >or=5 mm, and 0.28 (95% CI, 0.09-0.85) in those with body mass index >or= 23.2 (highest quartile) compared with those with body mass index < 19.0 (lowest quartile). These predictors are useful for selecting appropriately patients for careful follow-up examinations.

Adult↗
PubMed2006

The logics of leukocytapheresis as a natural biological therapy for inflammatory bowel disease.

Ulcerative colitis (UC) and Crohn's disease (CD) are debilitating idiopathic inflammatory bowel diseases (IBDs) with symptoms that impair ability to function and quality of life. The aetiology of IBD is inadequately understood and, therefore, drug therapy has been empirical instead of based on sound understanding of the disease mechanisms. This has been a major factor for poor drug efficacy and treatment-related side effects that often add to disease complications. The development of biologicals, notably infliximab, to block TNF-alpha reflects some progress, but there is major concern about their side effects and lack of long-term safety and efficacy profiles. However, IBD by its very nature is exacerbated and perpetuated by inflammatory cytokines, including TNF-alpha, IL-6 and IL-12, for which activated peripheral blood lymphocytes, monocytes/macrophages and granulocytes are major sources. Hence, activated leukocytes should be appropriate targets of therapy. At present, three strategies are available for removing excess and activated leukocytes by leukocytapheresis: centrifugation, Adacolumn and Cellsorba. Centrifugation can deplete lymphocytes or total leukocytes, whereas Adacolumn selectively adsorbs granulocytes and monocytes together with a smaller fraction of lymphocytes (FcgammaR- and complement receptor-bearing leukocytes), and Cellsorba non-selectively removes all three major leukocyte populations. Efficacy has ranged from 'none' to an impressive 93% together with excellent safety profiles and downmodulation of inflammation factors. Furthermore, leukocytapheresis has shown strong drug-sparing effects and reduced the number of patients requiring colectomy or exposure to unsafe immunosuppressants, such as cyclosporin A. Leukocytapheresis removes from the body cells that contribute to IBD and, therefore, unlike drugs, it is not expected to induce dependency or refractoriness.

Adsorption↗
PubMed2006

Overview: Helicobacter pylori and extragastric disease.

Isolation of the gastric spiral bacterium Helicobacter pylori totally reversed the false dogma that the stomach was sterile. In addition to its causal role in peptic ulceration, the newly identified bacterium has now been implicated in other gastric and even extragastric diseases, including chronic atrophic gastritis, gastric MALT lymphoma, gastric cancer, functional dyspepsia, idiopathic thrombocytopenic purpura (ITP), iron deficiency anemia, chronic urticaria, ischemic heart disease, and others. The majority of the reports are anecdotal, epidemiologic, or eradication studies, but there are also relevant in vitro studies. ITP represents one disease showing a strong link with H pylori infection. There are also accumulating data on the role of H pylori infection in iron deficiency anemia and ischemic heart disease. In summary, the association between H pylori infection and other extragut diseases is still controversial but worthy of further investigation.

Helicobacter Infections↗