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Masato Kawabata

Publications and source records attributed to Masato Kawabata.

18 recordsLinked to original sources
PubMed2006

Decreased susceptibility to fluoroquinolones and gyrA gene mutation in the Salmonella enterica serovar Typhi and Paratyphi A isolated in Katmandu, Nepal, in 2003.

Typhoid fever is the most common clinical diagnosis among febrile patients presenting to hospital in Katmandu. Salmonella enterica serovar Typhi (S. enterica serovar Typhi) and Salmonella enterica serovar Paratyphi A (S. enterica serovar Paratyphi A) with decreased susceptibility to fluoroquinolones and resistance to nalidixic acid are common in recent years. In the present study, we examined the in vitro susceptibility to fluoroquinolones and the presence of gyrA gene mutations in 30 clinical strains of S. Typhi and 39 of S. Paratyphi A, all of which were isolated in Katmandu, Nepal, in 2003. In those strains, we found that 73.3% and 94.9% of S. Typhi and S. Paratyphi A strains contained gyrA gene mutation, and showed the resistance to a quinolone, nalidixic acid, and decreased susceptibility to fluoroquinolones, ciprofloxacin, and levofloxacin. Although fluoroquinolones may still be useful as antibiotics for the treatment of typhoid fever, clinicians should be aware of the possibility of treatment failures of infections with S. Typhi and S. Paratyphi A strains with decreased susceptibility to fluoroquinolones.

Anti-Bacterial Agents↗
PubMed2006

Genetically engineered Bifidobacterium animalis expressing the Salmonella flagellin gene for the mucosal immunization in a mouse model.

BACKGROUND: A critical component of the host defense against enteric infections is the immunological response of the mucosal membrane, a major starting point of infectious disease, such as typhoid fever. The mucosal immune system consists of an integrated network of lymphoid tissues, mucous membrane-associated cells, and effector molecules. In the present study, we developed a recombinant Bifidobacterium animalis (B. animalis) genetically modified with the Salmonella flagellin gene for mucosal immunization as an oral typhoid vaccine. METHODS: We constructed an oral vaccine against Salmonella typhimurium, consisting of recombinant B. animalis containing the flagellin gene of Salmonella. The recombinant B. animalis was administered orally to mice every other day for 6 weeks. Anti-flagellin antibodies in the serum and stools were measured by enzyme-linked immunosorbent assay (ELISA). RESULTS: We detected significantly higher levels of flagellin-specific IgA in the serum and stools of the mice treated with the recombinant B. animalis containing the flagellin gene than was seen in those treated with parental B. animalis. CONCLUSIONS: Our findings suggest that an oral vaccination using recombinant B. animalis genetically modified with the flagellin gene of Salmonella may be effective against Salmonella infections.

Administration, Oral↗
PubMed2006

Limited allelic diversity of Plasmodium falciparum merozoite surface protein 1 gene from populations in the Solomon Islands.

Meiotic recombination generates allelic diversity in the Plasmodium falciparum merozoite surface protein 1 (msp1) gene. In this study, we monitored recombination-based diversity of msp1 in Guadalcanal, the Solomon Islands, where malaria transmission is high. We identified 5' recombinant types, 3' sequence types, and msp1 haplotypes (unique associations of 5' recombinant types and 3' sequence types), and compared them with those from areas of low transmission in Thailand and Vanuatu. The mean number of 5' recombinant types per person (multiplicity) was lower in Guadalcanal than in Thailand. Guadalcanal populations had 6-8 msp1 haplotypes; the numbers are comparable to Vanuatu but much lower than in Thailand. There were marked geographic differences in distribution of msp1 haplo-types. Linkage disequilibrium in msp1 was stronger in Guadalcanal than in Thailand, suggesting limited recombination events in the Solomon Islands. We suggest that the frequency of recombination events in msp1 is determined not only by transmission intensity but by the number of msp1 alleles prevalent and multiplicity of infections.

Adolescent↗
PubMed2006

Impact of single and multiple residual sprayings of pyrethroid insecticides against Triatoma dimidiata (Reduviiade; Triatominae), the principal vector of Chagas disease in Jutiapa, Guatemala.

This study investigated the impact of single, double, and triple insecticide sprayings on indoor infestation of Triatoma dimidiata in Jutiapa, Guatemala. Up to three successive insecticide sprayings were applied in villages, where the indoor infestation index was > 5% before each spraying round or located adjacent to the persistently infested villages. Among 64 villages with single spraying, the mean indoor infestation index reduced from 20.8% to 1.4% after 12 months, but rose to 8.1% after 33 months. In 40 double-sprayed villages, it decreased from 41.9% to 11.9% by the first spraying and to 4.8% by the second spraying. For 12 villages with triple spraying, it reduced from 40.6% to 13.2%, 10.9%, and 4.1% through each spraying round. Geographic analysis showed that originally highly infested villages were spatially clustered and were likely to remain infested after the sprayings. Indoor infestation of T. dimidiata can be controlled with less than three rounds of spraying.

Aerosols↗
PubMed2005

Determination of the period for establishment of a liver network echogenic pattern in Schistosoma japonicum infection.

Schistosomiasis is caused by infection with Schistosoma haematobium, S. mansoni, S. japonicum, or S. mekongi. S. japonicum infection results in liver cirrhosis at the final stage. A "network" (NW) echogenic pattern on hepatic ultrasonography appears to be specific to S. japonicum infection. The principal aim of the present study was to determine the exact year(s) or even month(s) required for the establishment of the liver NW echogenic pattern from the initial infection in young patients with schistosomiasis japonica since there are few data on this important point. We conducted yearly ultrasonographic, serologic, coprologic, and physical examinations of schistosomiasis patients in the Philippines from 1996 up to the present. During that period, the total number of patients examined was approximately 2,000, among whom we selected 2 patients for determination of the duration required for NW establishment, when they were 10 years old. Although the exact time of initial exposure to schistosomes cannot be determined, the duration for the establishment of NW was definitively confirmed in patient no. 1 to be between 19-24 months based on the results of serologic and coprologic examinations. For patient no. 2, the circumstantial evidence suggested that the establishment of a NW might require 5 to 6 years at maximum. To the best of our knowledge, this is the first evidence-based report on the determination of the period required for the establishment of a liver NW echogenic pattern in S. japonicum infection in the Philippines.

Animals↗
PubMed2005

Measles encephalitis in early pregnancy and after delivery.

We present two cases of measles encephalitis, one in early pregnancy and one after delivery. In case 1, the patient became unconscious 6 days after the appearance of a rash and was treated with glycerol and immunoglobulin. In case 2, the patient became unconscious 6 days after the appearance of a rash and was also treated with glycerol and immunoglobulin. Both of them recovered without any neurological sequelae. Pregnancy is a risk factor for severe measles complications, and vaccination should be promoted much more in countries with poor measles control, such as Japan.

Adult↗
PubMed2005

Quantitative detection of Salmonella enterica serovar Typhi from blood of suspected typhoid fever patients by real-time PCR.

We quantified the gene copies from Salmonella enterica serovar Typhi (S. Typhi) in the blood of patients suspected of having typhoid fever by using TaqMan-based real-time PCR (TaqMan assay) to target the S. Typhi flagellin gene in genomic DNAs isolated from blood samples. Of 55 blood samples taken from suspected typhoid fever patients, eight blood samples with a positive blood culture had S. Typhi loads ranging from 1.01 x 10(3) to 4.35 x 10(4) copies/ml blood, and from 47 blood samples with negative blood culture, there were 40 (85.1%) TaqMan assay-positive samples with loads ranging from 3.9 to 9.9 x 10(2) copies/ml blood. In the present study, the TaqMan assay detected more than 10(3) copies/ml blood of S. Typhi in all of the blood culture-positive samples, whereas less than 10(3) copies/ml blood of S. Typhi were detected in the blood culture-negative samples. Our findings suggest that a TaqMan assay may be useful for assessing S. Typhi loads, especially in cases of suspected typhoid fever with negative results from the standard blood culture test.

Bacteremia↗
PubMed2005

Identification and sequencing of Salmonella enterica serotype typhi isolates obtained from patients with perforation and non-perforation typhoid fever.

We describe the characterization of Salmonella enterica serovar Typhi, isolated from the blood of patients with perforation and non-perforation typhoid fever, by a combination of conventional microbiological tests, 16S rRNA gene sequencing, and flagellin gene and CDP-tyvelose epimerase (rfbE) gene sequencing. The 16S rRNA gene sequencing showed that there were four base mutations from perforation samples and only three from non-perforation samples. These findings indicated that the isolates were a strain of Salmonella enterica. The flagellin gene sequences from the two groups were 100% identical to that of the H1-d flagellin gene of serovar Typhi. Sequences of the rfbE from both groups were also 100% identical.

Adolescent↗
PubMed2005

Study on cyclospora cayetanensis associated with diarrheal disease in Nepal and Loa PDR.

A study of diarrheal diseases associated with Cyclospora cayetanensis was conducted in Nepal and Lao PDR. A total of 2083 samples were included in this study. Samples in Nepal were collected from October 1999 to August 2002 whereas samples in Lao PDR were collected from February 2002 to June 2003. C. cayetanensis was detected by direct microscopy using ultraviolet and differential interference contrast microscopy. The overall positive rate in Nepal was 9.2% (128/ 1397). A higher positive rate was observed in children aged 10 years and under (11.1%) and was lowest in the age group of 51-60 years (3.1%). A significantly higher positive rate was observed in the summer (rainy season) (12.6%) with the lowest prevalence in the spring (dry season) (1.8%) (p < 0.05). The positive rate was closely associated with rainfall (ml/month). Interestingly, only one of the total 686 samples (0.1%) from Lao PDR was found to be positive for Cyclospora oocysts.

Adolescent↗
PubMed2004

Comparison of three microscopic techniques for diagnosis of Cyclospora cayetanensis.

Cyclospora cayetanensis oocysts in the feces of humans from Kathmandu, Nepal were identified on the basis of their size and other morphological characteristics. We compared the detection of C. cayetanensis oocysts in the feces using three microscopic techniques such as formalin-ether sedimentation, sucrose centrifugal floatation, and direct smear. Standard procedures were used for the formalin-ether sedimentation and the sucrose centrifugal floatation techniques using 0.5 g of feces, however, the direct smear technique was performed using 10 microl of fecal suspension (0.005 g of feces) and observed under the fluorescent microscope. Of the 403 samples examined, 21 samples were positive for oocysts by all three techniques. Therefore, in these 21 samples, the number of oocysts recovered by the three techniques were compared. The highest number of oocyst was obtained by the sucrose centrifugal floatation technique. In contrast, the formalin-ether sedimentation technique was found to be the least reliable concentration technique for the detection of Cyclospora in human feces. Surprisingly, the direct smear technique was found to be an effective and rapid technique for diagnosis of C. cayetanensis making it a technique of choice for routine epidemiological investigation of the prevalence of this infection in human populations.

Centrifugation↗
PubMed2004

A cox-2 promoter-based replication-selective adenoviral vector to target the cox-2-expressing human bladder cancer cells.

PURPOSE: Cyclooxygenase-2 (Cox-2), an enzyme that catalyzes the synthesis of prostaglandins, is overexpressed in a variety of premalignant and malignant conditions, including urinary bladder cancer. In the present study, we examined the feasibility of using Cox-2 promoter-based replication-selective adenovirus for targeting bladder cancer cells that express Cox-2 transcriptional activity. EXPERIMENTAL DESIGN: A series of human cancer cell lines, including three bladder cancer cell lines (KK47, T24, and 5637), were evaluated for their Cox-2 and CAR (the Coxsackievirus and adenovirus receptor) mRNA expression levels by quantitative real-time PCR. AdE3-cox2-327, a replication-selective adenovirus in which the expression of E1a is controlled by the Cox-2 promoter, was generated, and its tissue-specific activity was tested in vitro and in vivo. RESULTS: Three bladder cancer cell lines express higher levels of Cox-2 mRNA than does the human prostate cancer cell line PC3, the primary cultured human benign prostatic fibroblast, PF cells, and the human colon cancer cell line Colo320. Relatively higher expression of CAR mRNA was detected in the KK47, 5637, respectively, and Colo320 than in the T24, PC-3, and PF cells. In vitro assays revealed significant growth suppression of both Cox-2- and CAR-expressing bladder cancer cells KK47 and 5637 in comparison with the other cells that lack Cox-2 expression and/or CAR expression. CONCLUSIONS: The present study demonstrated both specificity and efficacy of AdE3-cox2-327, a selectively replicated adenovirus, toward the Cox-2-expressing bladder cancer cells in vitro and in vivo. We also found that CAR expression in the target cancer cells is an important factor for the efficacy of selectively replicated adenovirus-based gene therapy.

Adenoviridae↗
PubMed2004

Relative frequencies of polymorphisms of variation in Block 2 repeats and 5' recombinant types of Plasmodium falciparum msp1 alleles.

The mechanisms producing the genetic polymorphism at Plasmodium falciparum merozoite surface antigen-1 locus (pfmsp1) include the insertion and deletion of the different type of dimorphic Block 2 9-nucleotide repeat units as well as the intragenic recombination. To study relative occurrence frequencies of these two distinct mechanisms, we have developed a sensitive PCR strategy to identify both 5' recombinant types and the number of Block 2 repeats from the same sample. This method can specifically detect the target 5' recombinant type (Blocks 2-6) at the sensitivity of 1-4 copies of the pfmsp1. Applying the new method to field isolates from the Solomon Islands enabled us to identify six different 5' recombinant types and variation in Block 2 repeat number in three of them, thus distinguishing 10 different alleles. Distribution of these alleles in local three villages in the study area suggests that frequencies of variation in the number of Block 2 9-bp repeats and recombination events within Blocks 2-6 are mutually independent and the frequency of repeat variation is relatively high as compared to that of recombination events at the pfmsp1 locus in P. falciparum populations from the Solomon Islands.

5' Untranslated Regions↗
PubMed2004

Mutations in the gyrA and parC genes and in vitro activities of fluoroquinolones in 91 clinical isolates of Neisseria gonorrhoeae in Japan.

BACKGROUND AND OBJECTIVES: Fluoroquinolone resistance in Neisseria gonorrhoeae has been associated with alternations in the quinolone-resistance determining regions in the gyrA and parC genes. GOAL: The goal of this study was to investigate the correlation between fluoroquinolone minimum inhibitory concentrations (MICs) and mutations in the gyrA and parC genes of 91 N. gonorrhoeae clinical isolates from Japan. STUDY DESIGN: The MICs of fluoroquinolones ciprofloxacin, levofloxacin, and gatifloxacin for 91 clinical isolates from male gonococcal urethritis in Hyogo or Osaka, Japan, were measured, and the gyrA and parC genes of these isolates were sequenced. RESULTS: Among 91 isolates tested, over 70% isolates were resistant to ciprofloxacin. We found that 4 mutations (Ser-91-Phe, Ser-91-Ile, Asp-95-Gly in gyrA, and Ser-88-Pro in parC) had significant correlation to MICs of fluoroquinolone (ciprofloxacin, levofloxacin, and gatifloxacin). CONCLUSION: Some mutations in QRDR had a significant relationship to the fluoroquinolone resistance of N. gonorrhoeae clinical isolates from Japan.

Anti-Infective Agents↗
PubMed2003

Rapid diagnosis of typhoid fever by PCR assay using one pair of primers from flagellin gene of Salmonella typhi.

Using the polymerase chain reaction (PCR) assay, we developed a rapid diagnosis method for Salmonella typhi infection in blood specimens from patients with typhoid fever. Primers were designed from the flagellin gene sequence, which would give an amplification product of 367 base pairs. In this study, the specificity of the assay, with no amplification, was seen for the other Salmonella strains with the flagellin gene, and not for non- Salmonella bacteria. For the sensitivity test, the protocol described allowed the detection of two to three copies of the Salmonella typhi genome, as determined by serial dilution of genomic DNA from Salmonella typhi. With the PCR technique, genomic DNA of Salmonella typhi was detected in 46 of 73 blood samples collected from patients with clinically suspected typhoid fever who had fever within 3 days of admission to the General Hospital, Makassar, South Sulawesi, Indonesia, and who had had no prior antibiotic treatment. The PCR results (63% positive cases) were compared with those of blood culture (13.7% positive cases) and the Widal test (35.6% positive cases), using the same samples from each of the 73 patients admitted to the General Hospital in Makassar. The time taken for PCR analysis of each sample was less than 12 h, compared with 3 to 5 days for blood or clot culture. The PCR with one pair of primers can be used as a novel, rapid diagnostic method for typhoid fever, particularly when results of standard culture assays are negative.

Adolescent↗
PubMed2003

[Lyme disease].

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Administration, Oral↗
PubMed2003

Distribution of two species of malaria, Plasmodium falciparum and Plasmodium vivax, on Lombok Island, Indonesia.

Medical and entomological surveys were conducted to determine the risk factors of Plasmodium falciparum and P. vivax infections on Lombok Island, Indonesia, to find the risk factors and the main mosquito vectors for each malaria. Multivariate longitudinal analysis demonstrated two significant risk factors for infection with P. falciparum: disappearance of P. vivax parasitemia (p<0.001) and a specific study site (p<0.001). In contrast, younger age (p=0.024) and the interpolated virtual density of An. subpictus (p=0.041) were significantly associated with increased risk of infection with P. vivax. Thus, it seems that the distribution of P. vivax was determined largely by the presence of An. subpictus, whilst that of P. falciparum was influenced by antagonism with P. vivax. This result shows the importance of following-up treated P. vivax patients to identify recrudescence of P. falciparum in this area.

Adolescent↗
PubMed2003

Effects of mefloquine usage on genetic polymorphism of Plasmodium falciparum in Thai-Myanmarese border.

We studied the polymorphism of msp-1, which encodes a major surface protein on the merozoite, isolated from blood samples from western Thailand in 1999. Our study area was a low-transmission area for malaria, where mefloquine has been used as an antimalarial drug since 1994. Forty-nine patients were confirmed to have contracted falciparum malaria twice within 24 weeks. The number of detected haplotypes in 49 patients was 89 at the first diagnosis and 68 at the second diagnosis. The mean number of haplotypes per patient significantly decreased from 1.82 to 1.39 but the frequency distributions of msp-1 haplotypes did not change significantly with the use of mefloquine. Our study strongly suggests that the antigenic diversity of Plasmodium falciparum is retained during mefloquine therapy in low-transmission areas.

Age Distribution↗