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Biomedical subjects

K Oguma

Publications and source records attributed to K Oguma.

At least 19 recordsLinked to original sources
PubMed2006

Quantification and genotyping of Cryptosporidium spp. in river water by quenching probe PCR and denaturing gradient gel electrophoresis.

A new detection method was developed for the simultaneous quantification and genotyping of Cryptosporidium spp. in river water. Several modifications made to the US EPA Method 1623 enabled high and stable recovery of Cryptosporidium from 40 L of river water (geometric mean = 35%, standard deviation = 8.7%). Quenching probe PCR (QProbe PCR) was used to quantify the 18S rRNA gene of Cryptosporidium spp. This method could successfully detect single oocysts in a sample, and the lower quantitation limit was as low as 2.5 oocysts/sample. In addition, denaturing gradient gel electrophoresis (DGGE) followed by DNA sequencing was used to identify the genotypes. These methods were applied to detect Cryptosporidium spp. in the Koyama River, Japan. The positive ratio was 69% (11/16) with the maximum concentration of 59 oocysts/100 L. Seven genotypes including two novel ones were identified. These results showed that this detection method could provide valuable information on Cryptosporidium in river water, both in the concentration and in the genotypes, which is essential for the precise assessment of waterborne risk to human health.

Animals↗
PubMed2006

Monitoring of human enteric viruses and coliform bacteria in waters after urban flood in Jakarta, Indonesia.

Floodwaters in Kampung Melayu village, Jakarta, Indonesia, as well as river water and consumable water (including groundwater and tap water) samples in flooded and non-flooded areas, were quantitatively analysed to assess occurrence of viruses and total coliforms and E. coli as bacterial indicators after flooding event. High numbers of enterovirus, hepatitis A virus, norovirus (G1, G2) and adenovirus were detected at high concentration in floodwaters and waters sampled from Ciliwung River which runs across metropolitan Jakarta and is used widely for agriculture and domestic purposes by poor residents. One out of three groundwater wells in the flooded area was contaminated with all viruses tested while no viruses were found in groundwater samples in non-flooded areas and tap water samples. The results revealed that human enteric viruses, especially hepatitis A virus and adenovirus, were prevalent in Jakarta, Indonesia. This study suggested that flooding posed a higher risk of viral infection to the people through contamination of drinking water sources or direct contact with floodwaters.

Base Sequence↗
PubMed2006

Effects of rainfall on the occurrence of human adenoviruses, total coliforms, and Escherichia coli in seawater.

A two-month survey was conducted in order to evaluate the effects of rainfall on the fate of microorganisms in seawater in the Tokyo Bay, Japan. The seawater sample (1,000 mL) was applied to a method to concentrate virus, followed by a quantification of human adenoviruses using the real-time PCR. Total coliforms and E. coli, which were determined by the colony forming method, were detected in all 47 seawater samples, while human adenoviruses were detected in 38 (81%) of the samples. The concentration of tested microorganisms showed 1-2 log units increase after rainfall events, followed by the gradual decrease to the level before the rainfall within a few days.

Adenoviridae↗
PubMed2005

Eradication of Helicobacter pylori increases platelet count in patients with idiopathic thrombocytopenic purpura in Japan.

BACKGROUND: The effect of Helicobacter pylori eradication on the platelet count in patients with thrombocytopenic purpura is controversial. In this multicentre study, we prospectively assessed the effect of H. pylori eradication therapy in idiopathic thrombocytopenic purpura patients. MATERIALS AND METHODS: Thirty-five consecutive patients with chronic idiopathic thrombocytopenic purpura (11 males and 24 females, a median age of 57) were assessed for H. pylori infection by use of a urea breath test. All patients received 1-week triple therapy (amoxicillin, clarithromycin, and lansoprazole) to eradicate H. pylori. At 6 months, idiopathic thrombocytopenic purpura patients with a platelet count recovery of greater than 100 x 10(9) L(-1) were defined as idiopathic thrombocytopenic purpura responders. RESULTS: Helicobacter pylori infection was observed in 25 (71%) of the 35 patients. All infected patients were cured. Eleven patients were identified as idiopathic thrombocytopenic purpura responders; 24 were considered nonresponders. Platelet counts improved by more than 100 x 10(9) L(-1) in 11 (44%) of the 25 patients cured of H. pylori infection, while none of the 10 patients H. pylori-negative patients experienced the same improvement (P = 0.015). Univariate analysis showed that H. pylori infection and its eradication were significant factors associated with platelet recovery (P = 0.015). CONCLUSIONS: Helicobacter pylori infection played a role in the pathogenesis of idiopathic thrombocytopenic purpura in approximately 30% of all patients assessed and 45% of the patients with H. pylori infection. Eradication of H. pylori in idiopathic thrombocytopenic purpura patients led to improved disease activity.

Adult↗
PubMed2004

Cryptosporidium monitoring system at a water treatment plant, based on waterborne risk assessment.

The water volume required for daily monitoring of Cryptosporidium (which can statistically ensure an annual risk of infection below 10(-4)), was assessed by evaluating the applicability of the Poisson lognormal (PLN) distribution in microbial risk assessment. PLN showed as good a fit to the observed data as to the negative binomial distribution. From the estimated PLN distributions for the source and finished water, the efficacy of the oocyst removal by the conventional water treatment process was estimated to follow log-normal distribution (median = 3.16 log10, 95% CI = 4.27-2.05 log10). The 365 consecutive negative results of daily monitoring for 180 L of finished water were found to be statistically equivalent to the annual risk of infection below 10(-4). This research also suggested the possibility of applying a qualitative detection method, such as CC-PCR, as a routine monitoring method for the quantitative risk management.

Animals↗
PubMed2003

Induction of intestinal IgA and IgG antibodies preventing adhesion of verotoxin-producing Escherichia coli to Caco-2 cells by oral immunization with liposomes.

AIMS: To examine the efficacy of liposome oral administration to induce systemic and mucosal immune responses against verotoxin-producing Escherichia coli (VTEC) and the effect of the induced antibodies on the binding of the bacteria to Caco-2 cells. METHODS AND RESULTS: Mice were immunized orally with VTEC antigen and monophosphoryl lipid A (MPL)-containing liposomes composed of dipalmitoylphosphatidylcholine, dipalmitoylphosphatidylserine and cholesterol (1 : 1 : 2, molar ratio) (PS-liposome). After immunization, significant IgA and IgG responses to VTEC were induced in both serum and the intestinal lavage fluid in all mice tested. Furthermore, anti-VTEC IgA and IgG antibodies in the lavage fluid effectively inhibited the adhesion of VTEC to Caco-2 cells. CONCLUSIONS: Oral immunization with liposome-associated E. coli O157:H7 antigen can induce significant systemic and mucosal antibody responses against the bacterial antigen and antibodies produced in the intestinal tract, thus functioning as inhibitors for preventing VTEC infection. SIGNIFICANCE AND IMPACT OF THE STUDY: Oral PS-liposome vaccines containing MPL have the potential usefulness for the induction of a protective mucosal immune response against intestinal diseases.

Administration, Oral↗
PubMed2003

Expression of HC subunits from Clostridium botulinum types C and D and their evaluation as candidate vaccine antigens in mice.

Two proteins representing the heavy-chain subunits of botulinum neurotoxin types C and D were expressed in Escherichia coli, and their vaccine potential was evaluated. Mice were vaccinated with doses ranging from 0.5 to 10 microg and were challenged with 10 to 10(5) 50% lethal doses of toxin. For the type C subunit protein, C50, two doses of 2 microg were required for full protection, while, for type D subunit protein, D50, two 1- microg doses were required. A bivalent vaccine consisting of a mixture of these two proteins also provided protection against both botulinum neurotoxin type C and type D challenge. Antibody levels in serum were determined by both enzyme-linked immunosorbent assays and serum neutralization assays

Animals↗
PubMed2001

Role of C-terminal region of HA-33 component of botulinum toxin in hemagglutination.

Using SDS-PAGE, we found that one subcomponent, hemagglutinin (HA-33), from the Clostridium botulinum progenitor toxin of type D strain 1873 and type C strain Yoichi had slightly smaller molecular sizes than those of type C and D reference strains, but other components did not. Based on N- and C-terminal sequence analyses of HA-33, a deletion of 31 amino acid residues from the C-terminus at a specific site was observed in the HA-33 proteins of both strains. The progenitor toxins from both strains showed poor hemagglutination activities, titers of 2(1) or less, which were much lower than titers from the reference strains (2(6)), and did not bind to erythrocytes. These results suggest strongly that the short C-terminal region of the HA-33 plays an essential role in the hemagglutination activity of the botulinum progenitor toxin. Additionally, a sequence motif search predicted that the C-terminal region of HA-33 has a carbohydrate-recognition subdomain.

Amino Acid Sequence↗
PubMed2001

In vivo synergy between green tea extract and levofloxacin against enterohemorrhagic Escherichia coli O157 infection.

We studied the synergistic effects of Japanese green tea extract (JGTE) and levofloxacin (LVFX) against enterohemorrhagic Escherichia coli (EHEC) infection in a gnotobiotic mouse model. Mice fed on JGTE conferred a significant degree of protection against an oral challenge with EHEC. Complete elimination of the bacteria from the mice, was however, difficult. The combination of JGTE and LVFX increased the survival rate and reduced damage to target organs. Thus, dietary supplementation with JGTE improved the therapeutic effects of antibiotic treatment.

Animals↗
PubMed2001

Therapeutic effect of anti-TNF-alpha antibody and levofloxacin (LVFX) in a mouse model of enterohemorrhagic Escherichia coli O157 infection.

The ability of an anti-TNF-alpha antibody to confer protection against enterohaemorrhagic Escherichia coli (EHEC) O157 was investigated in germfree IQI mice. The use of an antibiotic levofloxacin (LVFX) alone or with the antibody was also studied. Protection included an increase in survival rate. Treatment with the anti-TNF-alpha antibody inhibited the histological signs associated with EHEC infection but did not prevent the colonization of EHEC or production of Shiga toxin (Stx). No clinical signs were observed and EHEC was completely eliminated in the mouse model receiving both anti-TNF-alpha antibody and LVFX. Anti-TNF-alpha antibody suppressed inflammatory cytokine response in the mouse kidney and brain by EHEC infection.

Animals↗
PubMed2001

A randomized open trial for comparison of proton pump inhibitors, omeprazole versus rabeprazole, in dual therapy for Helicobacter pylori infection in relation to CYP2C19 genetic polymorphism.

BACKGROUND AND AIM: The genetic polymorphism of cytochrome P450 (CYP) 2C19 has been shown to influence the efficacy of Helicobacter pylori eradication therapy with a proton pump inhibitor (PPI) and amoxicillin (so-called dual therapy). Omeprazole, a widely used PPI, and rabeprazole, a new PPI, are metabolized in different pathways in terms of CYP2C19 genetic polymorphisms. In this study, we compared the efficacy of omeprazole and rabeprazole in a 2-week dual therapy in relation to CYP2C19 polymorphism. METHODS: One hundred and ninety-nine patients with peptic ulcer disease were randomly assigned to receive one of the following regimens: 500 mg t.i.d. amoxicillin together with either 20 mg b.i.d. omeprazole or 10 mg b.i.d rabeprazole. The eradication of H. pylori was evaluated by using a bacterial culture and a [(13)C]-urea breath test at 1--2 months after completion of treatment. Cytochrome P4502C19 polymorphism was analyzed by using polymerase chain reaction-restriction fragment length polymorphism. RESULTS: Intention-to-treat-based cure rates for the omeprazole or rabeprazole regimens were 66.3% (95% CI, 56--75) and 62.4% (95% CI, 52--71), respectively, without significant difference. Cytochrome P4502C19 genetic polymorphism did not influence the cure rates in either of these regimens. We analyzed various factors associated with treatment failure (PPI, CYP2C19 genotype, and smoking habit) by using multiple logistic regression; smoking was the only significant independent factor for treatment failure. CONCLUSION: Omeprazole and rabeprazole were equally effective in combination with amoxicillin in eradicating H. pylori, irrespective of the PPI used (omeprazole or rabeprazole) and CYP2C19 genetic polymorphism. Smoking significantly decreased the cure rate of H. pylori infection in the dual therapy.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed2001

Determination of pyrimidine dimers in Escherichia coli and Cryptosporidium parvum during UV light inactivation, photoreactivation, and dark repair.

UV inactivation, photoreactivation, and dark repair of Escherichia coli and Cryptosporidium parvum were investigated with the endonuclease sensitive site (ESS) assay, which can determine UV-induced pyrimidine dimers in the genomic DNA of microorganisms. In a 99.9% inactivation of E. coli, high correlation was observed between the dose of UV irradiation and the number of pyrimidine dimers induced in the DNA of E. coli. The colony-forming ability of E. coli also correlated highly with the number of pyrimidine dimers in the DNA, indicating that the ESS assay is comparable to the method conventionally used to measure colony-forming ability. When E. coli were exposed to fluorescent light after a 99.9% inactivation by UV irradiation, UV-induced pyrimidine dimers in the DNA were continuously repaired and the colony-forming ability recovered gradually. When kept in darkness after the UV inactivation, however, E. coli showed neither repair of pyrimidine dimers nor recovery of colony-forming ability. When C. parvum were exposed to fluorescent light after UV inactivation, UV-induced pyrimidine dimers in the DNA were continuously repaired, while no recovery of animal infectivity was observed. When kept in darkness after UV inactivation, C. parvum also showed no recovery of infectivity in spite of the repair of pyrimidine dimers. It was suggested, therefore, that the infectivity of C. parvum would not recover either by photoreactivation or by dark repair even after the repair of pyrimidine dimers in the genomic DNA.

Animals↗
PubMed2001

Immunoglobulin G1 antibody response to Helicobacter pylori heat shock protein 60 is closely associated with low-grade gastric mucosa-associated lymphoid tissue lymphoma.

Gastric mucosa-associated lymphoid tissue (MALT) lymphoma is related to Helicobacter pylori infection. Specifically, it has been pointed out that pathogenesis of MALT lymphoma involves the 60-kDa heat shock protein (hsp60). To investigate humoral immune responses to the H. pylori hsp60 in patients with gastroduodenal diseases and patients with MALT lymphoma, the hsp60 of H. pylori was expressed with a glutathione S-transferase fusion protein and was purified (recombinant hsp60). Sera were obtained from H. pylori-positive patients with gastroduodenal diseases (MALT lymphoma, n = 13; gastric ulcer, n = 20; duodenal ulcer, n = 20; gastritis, n = 20) and from H. pylori-negative healthy volunteers (n = 9). Sera from patients with MALT lymphoma were also obtained at two times: before and after eradication therapy. Antibodies to hsp60 and H. pylori were assessed by enzyme-linked immunosorbent assay. The levels of immunoglobulin G (IgG) antibodies to the hsp60 of H. pylori-positive patients with gastroduodenal diseases were significantly elevated compared to those in the controls. The levels of IgG1 antibodies to hsp60 were elevated and correlated with the levels of anti-H. pylori antibodies in patients with MALT lymphoma. Humarol immunity against hsp60 may be important and relevant to gastroduodenal diseases induced by H. pylori infection.

Adult↗
PubMed2001

Relationship between susceptibility to hemolytic-uremic syndrome and levels of globotriaosylceramide in human sera.

The relationship between differential susceptibility to hemolytic-uremic syndrome (HUS) and levels of globotriaosylceramide (Gb3) in serum was studied in patients infected with verotoxin-producing Escherichia coli (VTEC). The serum Gb3 levels in patients with HUS were lower than these in diarrheal patients without subsequent HUS or in patients without clinical symptoms, indicating that individuals with a lower content of serum Gb3 show a higher incidence of HUS following VTEC infection.

Adolescent↗
PubMed2001

Inhibition of Vero cell cytotoxic activity in Escherichia coli O157:H7 lysates by globotriaosylceramide, Gb3, from bovine milk.

In order to clarify the presence and verotoxin (VT) inhibitory activity of globotriaosylceramide (Gb3) in bovine milk, we analyzed neutral glycosphingolipids (GSLs) from bovine milk and investigated the inhibitory effect of bovine milk Gb3 on the cytotoxicity of VT2. Five species of neutral GSLs, designated as N-1, N-2, N-3, N-4, and N-5, were separated on thin-layer chromatography (TLC). N-1, N-2, and N-3 showed the same mobility as glucosylceramide, lactosylceramide, and Gb3 on the TLC plate, respectively. N-4 and N-5 GSLs migrated below globoside on the TLC plate. N-3 GSL having the same TLC mobility as Gb3 from bovine milk was immunologically identified as Gb3 by monoclonal antibody against Gb3, anti-CD77 monoclonal antibody. Furthermore, the effect of bovine milk Gb3 on VT2-induced cytotoxicity was investigated. We found that treatment of VT2 with bovine milk Gb3 can reduce the cytotoxic effect of VT2.

Adsorption↗
PubMed2001

Adsorption effect of activated charcoal on enterohemorrhagic Escherichia coli.

The adsorption property of activated charcoal on verotoxin (VT)-producing Escherichia coli (VTEC) was examined using E. coli O157:H7. In the present study, E. coli O157:H7 strains were effectively adsorbed by activated charcoal. Adsorption was dose-dependent, and the maximum adsorption occurred within 5 min. At 10 mg of activated charcoal, bacteria tested were completely adsorbed. Activated charcoal also had the capacity to adsorb toxin (verotoxin 2) activity from the bacterial extract. Furthermore, the adsorption efficiency of activated charcoal for the normal bacterial flora in the intestine was assessed using Enterococcus faecium, Bifidobacterium thermophilum, and Lactobacillus acidophilus. Activated charcoal showed lower binding capacity to the normal bacterial flora tested than that to E. coli O157:H7 strains. These results suggest that activated charcoal could be a good adsorbent system for the removal of VTEC and verotoxin.

Adsorption↗
PubMed2001

Determination of traces of cadmium in natural water samples by flow injection on-line preconcentration-graphite furnace atomic absorption spectrometry.

A flow injection on-line preconcentration-graphite furnace atomic absorption spectrometric method was developed for the determination of traces of cadmium in natural water samples. Cadmium in samples was adsorbed on an iminodiacetate-type chelating resin, Muromac A-1 microcolumn (3 mm i.d. and 10 mm long), and then eluted with 2 mol l-1 HNO3. The eluate was introduced into the injection tip of an autosampler. The eluate zone with the highest analyte concentration was injected into the graphite furnace by cooperation of a peristaltic pump and a syringe pump of the autosampler, which were controlled by a programmable controller. The present system was successfully applied to the determination of cadmium in natural water samples. A detection limit of 0.2 ng l-1 was obtained with 12 ml sample loading. The recoveries were 99 and 108% for tap water (4 ml loading) and underground water (12 ml loading), respectively. Analytical results obtained for a river water reference material (JAC-0031, Japan Society for Analytical Chemistry) were close to the reference value.

Cadmium↗