Publications by authors named "Seigo Yamamoto"

52 Publications

A mutant gene for albino body color is widespread in natural populations of tanuki (Japanese raccoon dog).

Genes Genet Syst 2021 May 6;96(1):33-39. Epub 2021 Mar 6.

Primate Research Institute, Kyoto University.

Albino mutants (white coat and red eyes) of tanuki (Nyctereutes procyonoides viverrinus) have been repeatedly found in the Central Alps area of Japan. We recently reported that an albino tanuki from Iida, a city in this area, lacks the third exon of the TYR gene encoding tyrosinase, which is essential for melanin synthesis. The absence of this exon was due to the chromosomal deletion of a complex structure. In the present study, we analyzed TYR of another albino tanuki that was found in Matsusaka, a city located outside the mountainous area. In this animal, the third exon was also lost, and the loss was due to a deletion in which the structure was identical to that of the Iida mutant. Our results indicate, in consideration of the complex structure of the deletion, that the two albino animals inherited a single deletion that arose in their common ancestor. Iida and Matsusaka are approximately 170 km apart. This is, to our knowledge, the first report of an albino mutant gene that is widely distributed in mammalian natural populations. As the origin of this mutation is not known, the distance covered by the mutant gene remains unclear. If we assume that the mutation occurred halfway between Iida and Matsusaka, we can predict the migration distance to be approximately 85 km; however, if the mutation occurred at any other place, a longer distance would be predicted. Natural selection against albino tanuki may be relaxed because of a recent increase in food resources and refuge in urban areas.
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http://dx.doi.org/10.1266/ggs.20-00047DOI Listing
May 2021

Isolation of Severe Fever with Thrombocytopenia Syndrome Virus from Various Tick Species in Area with Human Severe Fever with Thrombocytopenia Syndrome Cases.

Vector Borne Zoonotic Dis 2021 May 3;21(5):378-384. Epub 2021 Feb 3.

Department of Veterinary Sciences, Faculty of Agriculture, University of Miyazaki, Miyazaki, Japan.

Severe fever with thrombocytopenia syndrome (SFTS), caused by , generally called SFTS virus (SFTSV), is an emerging zoonosis in East Asia. In Japan, 50-100 cases of SFTS have been reported each year since the first case was reported in 2013. SFTS is a tick-borne infectious disease, and SFTSV has been isolated from ticks in China and South Korea. and are considered the primary vectors in Japan. However, the other tick species seldom feeding on humans might also play an important role in maintaining the virus in nature. In this study, we collected ticks on vegetation around the location where two SFTS patients were estimated to have been infected in Miyazaki Prefecture, Japan, isolated live SFTSV, and performed a phylogenetic analysis. A total of 257 ticks were collected, and SFTSV RNA was detected in 19.5% (9/46) of tick pools. A total of 10 infectious SFTSVs were successfully isolated from , , , , and . Furthermore, the whole viral sequences isolated from ticks were highly homologous to sequences isolated from SFTS patients in the same sampling area in the past. These results suggest that SFTSVs are maintained in these tick species in the sampling area and sporadically transmitted to humans. Surveillance of SFTSV in ticks provides important information about the risk of incidental transmission to humans.
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http://dx.doi.org/10.1089/vbz.2020.2720DOI Listing
May 2021

Genomic Features of Revealed by Intraspecies Comparison and Detailed Comparison With .

Front Microbiol 2019 6;10:2787. Epub 2019 Dec 6.

Department of Bacteriology, Faculty of Medical Sciences, Kyushu University, Fukuoka, Japan.

is the causative agent of Far-Eastern spotted fever (FESF). In Japan, a human case of FESF was identified in Sendai in Miyagi Prefecture in 2008, and bacteria were isolated from ticks collected in the suspected geographical area of infection. Although the intraspecies genome diversity of Rickettsia has been poorly investigated, our recent analysis revealed extremely low genomic diversity of , the agent of Japanese spotted fever, which is a close relative of . In this study, to investigate the genomic diversity of and understand the genetic relationship between Japanese and Chinese isolates, we sequenced three isolates from ticks collected in Sendai and one isolate from a tick collected in Inner Mongolia, China, and performed genomic comparisons between these isolates and strain 054, the type strain isolated from a tick in Heilongjiang Province, China. Although the three Japanese strains were isolated in 2008, 2009, and 2012, their genome sequences were identical, indicating that ticks carrying a single clone have been distributed in Sendai, Japan. Among the five isolates, only 81 SNPs and 13 insertion/deletion sites were identified, despite the significant differences in these isolates both geographically and temporally. A significant portion of the 81 SNPs (16/81) were found to be recombinogenic. These results indicate low genomic diversity of , as observed in . We further performed a detailed genomic comparison of and to accurately define conserved and species-specific genes. This analysis revealed that although notable variations were found in the genomic loci encoding RelA/SpoT family proteins and tandem repeats in major surface proteins, there was only a small difference in the gene repertoire between the two species, suggesting that SNPs and small InDels are responsible for the functional or physiological differences between the two species, if present. Through this analysis, several species-specific genomic regions that can serve as ideal PCR targets for distinguishing and were also identified.
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http://dx.doi.org/10.3389/fmicb.2019.02787DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6908463PMC
December 2019

Evaluation of Diagnostic Assay for Rickettsioses Using Duplex Real-Time PCR in Multiple Laboratories in Japan.

Jpn J Infect Dis 2018 Jul 27;71(4):267-273. Epub 2018 Apr 27.

Department of Food and Nutritional Sciences, Graduate School of Integrated Pharmaceutical and Nutritional Sciences, University of Shizuoka.

Tsutsugamushi disease and Japanese spotted fever are representative rickettsioses in Japan, and are caused by infection with Orientia tsutsugamushi and Rickettsia japonica, respectively. For molecular-based diagnosis, conventional PCR assays, which independently amplify respective rickettsial DNA, are usually used; however, this approach is time-consuming. Here, we describe a new duplex real-time PCR assay for the simultaneous detection of O. tsutsugamushi and spotted fever group rickettsiae, and its evaluation using several PCR conditions in 6 public health laboratories. The detection limit of the assay was estimated to be 10 copies and the sensitivity was almost identical to that of 3 conventional PCR methods. A total of 317 febrile patients were selected as clinically suspected or confirmed cases of rickettsioses. The detection efficiency of this assay for O. tsutsugamushi from blood or skin (eschar) specimens appeared to be almost the same as that of the conventional PCR method, even when performed in different laboratories, whereas the efficiency for spotted fever group rickettsiae tended to be higher than that of the 2 traditional double PCR assays. Our duplex real-time PCR is thus a powerful tool for the rapid diagnosis of rickettsioses, especially at the acute stage of infection.
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http://dx.doi.org/10.7883/yoken.JJID.2017.447DOI Listing
July 2018

Extremely Low Genomic Diversity of Rickettsia japonica Distributed in Japan.

Genome Biol Evol 2017 01;9(1):124-133

Department of Bacteriology, Faculty of Medical Sciences, Kyushu University, Fukuoka, Japan.

Rickettsiae are obligate intracellular bacteria that have small genomes as a result of reductive evolution. Many Rickettsia species of the spotted fever group (SFG) cause tick-borne diseases known as "spotted fevers". The life cycle of SFG rickettsiae is closely associated with that of the tick, which is generally thought to act as a bacterial vector and reservoir that maintains the bacterium through transstadial and transovarial transmission. Each SFG member is thought to have adapted to a specific tick species, thus restricting the bacterial distribution to a relatively limited geographic region. These unique features of SFG rickettsiae allow investigation of how the genomes of such biologically and ecologically specialized bacteria evolve after genome reduction and the types of population structures that are generated. Here, we performed a nationwide, high-resolution phylogenetic analysis of Rickettsia japonica, an etiological agent of Japanese spotted fever that is distributed in Japan and Korea. The comparison of complete or nearly complete sequences obtained from 31 R. japonica strains isolated from various sources in Japan over the past 30 years demonstrated an extremely low level of genomic diversity. In particular, only 34 single nucleotide polymorphisms were identified among the 27 strains of the major lineage containing all clinical isolates and tick isolates from the three tick species. Our data provide novel insights into the biology and genome evolution of R. japonica, including the possibilities of recent clonal expansion and a long generation time in nature due to the long dormant phase associated with tick life cycles.
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http://dx.doi.org/10.1093/gbe/evw304DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5381555PMC
January 2017

Imported case of acute respiratory tract infection associated with a member of species nelson bay orthoreovirus.

PLoS One 2014 25;9(3):e92777. Epub 2014 Mar 25.

Influenza virus Research Center, National Institute of Infectious Diseases, Musashimurayama, Tokyo, Japan.

A Japanese man suffered from acute respiratory tract infection after returning to Japan from Bali, Indonesia in 2007. Miyazaki-Bali/2007, a strain of the species of Nelson Bay orthoreovirus, was isolated from the patient's throat swab using Vero cells, in which syncytium formation was observed. This is the sixth report describing a patient with respiratory tract infection caused by an orthoreovirus classified to the species of Nelson Bay orthoreovirus. Given the possibility that all of the patients were infected in Malaysia and Indonesia, prospective surveillance on orthoreovirus infections should be carried out in Southeast Asia. Furthermore, contact surveillance study suggests that the risk of human-to-human infection of the species of Nelson Bay orthoreovirus would seem to be low.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0092777PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3965453PMC
December 2014

Estimation of chloroform inhalation dose by other routes based on the relationship of area under the blood concentration-time curve (AUC)-inhalation dose to chloroform distribution in the blood of rats.

J Environ Sci Health A Tox Hazard Subst Environ Eng 2014 ;49(3):253-61

a Japan Bioassay Research Center, Japan Industrial Safety and Health Association , Hadano , Kanagawa , Japan.

The present study investigated the time-course changes of concentration of chloroform (CHCl3) in the blood during and after exposure of male rats to CHCl3 by inhalation. Increasing the dose of CHCl3 in the inhalation exposed groups caused a commensurate increase in the concentration of CHCl3 in the blood and the area under the blood concentration-time curve (AUC). There was good correlation (r = 0.988) between the inhalation dose and the AUC/kg body weight. Based on the AUC/kg body weight-inhalation dose curve and the AUC/kg body weight after oral administration, inhalation equivalent doses of orally administered CHCl3 were calculated. Calculation of inhalation equivalent doses allows the body burden due to CHCl3 by inhalation exposure and oral exposure to be directly compared. This type of comparison facilitates risk assessment in humans exposed to CHCl3 by different routes. Our results indicate that when calculating inhalation equivalent doses of CHCl3, it is critical to include the AUC from the exposure period in addition to the AUC after the end of the exposure period. Thus, studies which measure the concentration of volatile organic compounds in the blood during the inhalation exposure period are crucial. The data reported here makes an important contribution to the physiologically based pharmacokinetic (PBPK) database of CHCl3 in rodents.
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http://dx.doi.org/10.1080/10934529.2014.846191DOI Listing
August 2014

Novel method using hybrid markers: development of an approach for pulmonary measurement of multi-walled carbon nanotubes.

J Occup Med Toxicol 2013 Oct 25;8(1):30. Epub 2013 Oct 25.

Japan Bioassay Research Center, Japan Industrial Safety and Health Association, 2445 Hirasawa, Hadano, Kanagawa 257-0015, Japan.

Background: Multi-walled carbon nanotubes (MWCNT)s are suspected to induce pulmonary and pleural cancers due to their asbestos-like configurations. Therefore, accurate measurement of inhaled nanotubes in target organs is crucial for assessing cancer risk. Conventionally, nanotubes are measured after combustion at high temperature for conversion into CO2; however, the sensitivity is poor and the method lacks versatility. We have therefore developed a novel approach using hybrid markers for nanotube analysis, featuring high sensitivity and the capacity to conduct repeated analyses. The method involves adsorption of markers to nanotubes, followed by their desorption and assessment by means of high performance liquid chromatography (HPLC).

Methods: Recovery of MWCNT from rat lungs was conducted, and pulmonary MWCNT amounts were determined using rats intratracheally-exposed to MWCNT aerosol at 5 mg/m3 for 6 hours/day.

Results: The correlation coefficient for the calibration curve of MWCNT weight and the HPLC area was 0.9991. Consequently, the lower quantitation limit yielded was 0.2 μg. The recovery was 92-98% at approximately 0.4-2.0 μg demonstrating that MWCNTs in the lung could be measured accurately and precisely.

Conclusions: We have developed a novel method using a hybrid marker approach for nanotube analysis, featuring very high sensitivity and the capacity to conduct repeated analyses. We further confirmed correlations between the amounts of nanotubes and markers and pulmonary nanotube measurement demonstrated that trace amounts could be detected with values closely relating to the administered dose, verifying that the method is sensitive and precise.
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http://dx.doi.org/10.1186/1745-6673-8-30DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4177529PMC
October 2013

Tsutsugamushi disease caused by Shimokoshi-type Orientia tsutsugamushi: the first report in Western Japan.

Am J Trop Med Hyg 2013 Jun 15;88(6):1217-9. Epub 2013 Apr 15.

Division of Hematology and Oncology, Division of Infection Control and Senior Fellow Laboratory, University of Fukui, Fukui, Japan.

An 85-year-old female farmer was admitted to our hospital for fever, general fatigue, and skin rash. Cephalosporin was not effective and minocycline was dramatically effective. An eschar was discovered on her inguinal region after the defervescence. Laboratory examination of serum taken 12 days after onset of the illness showed elevated titers of antibodies against the Shimokoshi strain of Orientia tsutsugamushi. The gene sequence analysis of specimen from the patient's eschar revealed high similarity to the Shimokoshi strain by nested polymerase chain reaction. Therefore, this patient was diagnosed as a case of Shimokoshi-type tsutsugamushi disease, which has not previously been reported in Western Japan. Recently, cases of this type have also been confirmed in northeastern Japan, suggesting the need for further epidemiological studies.
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http://dx.doi.org/10.4269/ajtmh.12-0740DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3752827PMC
June 2013

Distribution of blood and tissue concentrations in rats by inhalation exposure to 1,2-dichloroethane.

J Environ Sci Health A Tox Hazard Subst Environ Eng 2013 ;48(9):1031-6

Japan Bioassay Research Center, Japan Industrial Safety and Health Association, Hadano, Kanagawa, Japan.

The compound 1,2-dichloroethane (DCE) is a ubiquitous environmental contaminant. The primary route of exposure of humans to DCE is inhalation of its vapor. The present investigation was undertaken to determine the distribution and accumulation of DCE in the blood, lung, liver, brain, kidney and abdominal fat of rats during and after inhalation exposure. Male rats were exposed to 160 ppm (v/v) of DCE vapor for 360 min and the concentrations of DCE in the blood and tissues during the inhalation exposure period and after the end of the exposure period were measured. DCE accumulation in the abdominal fat was much greater than that in the blood and other tissues. The information we obtained in this study is useful basic data pertaining to the pharmacokinetics of DCE and DCE-mediated carcinogenicity: Our results suggest that one of the factors involved in the induction of peritoneal tumors in rats exposed to DCE vapor by inhalation is DCE accumulation in the abdominal fat.
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http://dx.doi.org/10.1080/10934529.2013.773765DOI Listing
September 2013

A novel approach, based on BLSOMs (Batch Learning Self-Organizing Maps), to the microbiome analysis of ticks.

ISME J 2013 May 10;7(5):1003-15. Epub 2013 Jan 10.

Division of Collaboration and Education, Research Center for Zoonosis Control, Hokkaido University, Sapporo, Hokkaido, Japan.

Ticks transmit a variety of viral, bacterial and protozoal pathogens, which are often zoonotic. The aim of this study was to identify diverse tick microbiomes, which may contain as-yet unidentified pathogens, using a metagenomic approach. DNA prepared from bacteria/archaea-enriched fractions obtained from seven tick species, namely Amblyomma testudinarium, Amblyomma variegatum, Haemaphysalis formosensis, Haemaphysalis longicornis, Ixodes ovatus, Ixodes persulcatus and Ixodes ricinus, was subjected to pyrosequencing after whole-genome amplification. The resulting sequence reads were phylotyped using a Batch Learning Self-Organizing Map (BLSOM) program, which allowed phylogenetic estimation based on similarity of oligonucleotide frequencies, and functional annotation by BLASTX similarity searches. In addition to bacteria previously associated with human/animal diseases, such as Anaplasma, Bartonella, Borrelia, Ehrlichia, Francisella and Rickettsia, BLSOM analysis detected microorganisms belonging to the phylum Chlamydiae in some tick species. This was confirmed by pan-Chlamydia PCR and sequencing analysis. Gene sequences associated with bacterial pathogenesis were also identified, some of which were suspected to originate from horizontal gene transfer. These efforts to construct a database of tick microbes may lead to the ability to predict emerging tick-borne diseases. Furthermore, a comprehensive understanding of tick microbiomes will be useful for understanding tick biology, including vector competency and interactions with pathogens and symbionts.
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http://dx.doi.org/10.1038/ismej.2012.171DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3635243PMC
May 2013

Molecular and serological investigation of Leptospira and leptospirosis in dogs in Japan.

J Med Microbiol 2013 Apr 21;62(Pt 4):630-636. Epub 2012 Dec 21.

Department of Bacteriology, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku-ku, Tokyo 162-8640, Japan.

Canine leptospirosis, which is caused by infection with pathogenic Leptospira species, occurs worldwide, but information regarding the causative Leptospira serotypes and genotypes and their effects on virulence in dogs remains limited. Monitoring acute leptospirosis in dogs as sentinels can also aid in estimating the risk of human leptospirosis, particularly when the disease is rare, as it currently is in Japan. Among 283 clinically suspected cases of leptospirosis diagnosed from August 2007 to March 2011 in Japan, 83 cases were laboratory diagnosed as leptospirosis by blood culture, a rise in antibody titres in paired sera using a microscopic agglutination test (MAT) and/or DNA detection using flaB-nested PCR. The infected dogs comprised hunting dogs (31 dogs) and companion animals (50 dogs) and two unknown; 63.4 % of the infected dogs were males. The mortality rate was 53.2 %. A rise of at least fourfold in MAT titre was detected in 30 dogs whose paired serum samples were obtained, and the predominant reactive serogroup was Hebdomadis (53.3 %), followed by Australis (16.7 %) and Autumnalis (16.7 %). Leptospira interrogans was isolated from 45 dogs of the following serogroups: Australis (16), Autumnalis (six), Canicola (one), Hebdomadis (21) and Icterohaemorrhagiae (one). All of these serogroups caused lethal infections (57.1-100 %). Genetic heterogeneity was demonstrated in serogroups Australis, Autumnalis and Hebdomadis by multilocus sequence typing (MLST) and/or RFLP analysis based on PFGE. In serogroup Hebdomadis, each genotype determined by MLST had a unique mortality rate in the infected dogs. Although classic canine leptospirosis is associated with serovars Canicola and Icterohaemorrhagiae, serogroup Hebdomadis has become the predominant serogroup causing high mortality in Japan. This study suggests that the virulence of members of serogroup Hebdomadis in dogs may be associated with the genotypes in this serogroup.
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http://dx.doi.org/10.1099/jmm.0.050039-0DOI Listing
April 2013

Detection and characterization of p44/msp2 transcript variants of Anaplasma phagocytophilum from naturally infected ticks and wild deer in Japan.

Jpn J Infect Dis 2012 ;65(1):79-83

Department of Food and Nutritional Sciences, Graduate School of Nutritional and Environmental Sciences, Global Center of Excellence Program, University of Shizuoka, Shizuoka, Japan.

Anaplasma phagocytophilum is an obligate intracellular bacterium and causes a febrile illness in humans and livestock. In nature, this bacterium is sustained in a tick-mammal cycle. Several p44/msp2-related genes are expressed from a single expression locus by gene conversion. In this study, we obtained 119 cDNA sequences of p44/msp2 transcripts from A. phagocytophilum in 6 Haemaphysalis ticks and 3 wild sika deer (Cervus nippon) in Japan. These 119 sequences were classified into 36 different variant sequences based on their similarities. The 36 cDNA sequences were phylogenetically grouped into 2 major clusters--tick- and deer-associated. The tick-associated sequences were further classified into 4 distinct subclusters, suggesting that A. phagocytophilum in ticks seems to selectively express specific p44/msp2 transcripts, such as the transcripts in the 4 subclusters that were closely related to previously identified p44/msp2 genes. The deer-associated sequences were also grouped into 4 subclusters, but these transcripts were probably more diverse than the transcripts derived from ticks. This might be due to the relatively nonselective expression of p44/msp2 in deer or the strain differences in A. phagocytophilum from ticks and deer in separate geographic regions or both. Thus, this study may contribute to the understanding of A. phagocytophilum p44/msp2 expression in nature in Japan.
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May 2012

Chloroform distribution and accumulation by combined inhalation plus oral exposure routes in rats.

J Environ Sci Health A Tox Hazard Subst Environ Eng 2010 Oct;45(12):1616-24

Japan Bioassay Research Center, Japan Industrial Safety and Health Association, Hadano, Kanagawa, Japan.

The present investigation was undertaken to determine the distribution and accumulation of chloroform in the blood, liver, kidney and abdominal fat of rats after simultaneous exposure by two routes, inhalation and oral. To distinguish the contribution of each route, unmodified chloroform (CHCl3) was administered by inhalation and deuterated chloroform (CDCl3) was administered orally. Exposure by inhalation and oral administration resulted in CHCl3 and CDCl3 concentrations in the tissues which were significantly higher than when exposure was by either inhalation or oral administration alone. This is the first study to follow the contribution of each of two routes of chloroform exposure on chloroform distribution and accumulation in target tissues. Our results indicate that when assessing the toxicity and carcinogenicity of chloroform, exposure routes, especially the effects of exposure by multiple routes, must be taken into consideration.
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http://dx.doi.org/10.1080/10934529.2010.506121DOI Listing
October 2010

Genome comparison and phylogenetic analysis of Orientia tsutsugamushi strains.

DNA Res 2010 Oct 3;17(5):281-91. Epub 2010 Aug 3.

Division of Microbiology, Department of Infectious Diseases, Faculty of Medicine, University of Miyazaki, 5200 Kiyotake, Miyazaki 899-1692, Japan.

Orientia tsutsugamushi (OT) is an obligate intracellular bacterium belonging to the family Rickettsiaceae and is the causative agent of scrub typhus, or Tsutsugamushi disease. The complete genome sequences of two OT strains (Boryong and Ikeda) have recently been determined. In the present study, we performed a fine genome sequence comparison of these strains. Our results indicate that although the core gene set of the family Rickettsiaceae is highly conserved between the two strains, a common set of repetitive sequences have been explosively amplified in both genomes. These amplified repetitive sequences have induced extensive genome shuffling and duplications and deletions of many genes. On the basis of the results of the genome sequence comparison, we selected 11 housekeeping genes and carried out multilocus sequence analysis of OT strains using the nucleotide sequences of these genes. This analysis revealed for the first time the phylogenetic relationships of representative OT strains. Furthermore, the results suggest the presence of an OT lineage with higher potential for virulence, which may explain the clinical and epidemiological differences between 'classic' and 'new' types of Tsutsugamushi disease in Japan.
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http://dx.doi.org/10.1093/dnares/dsq018DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2955711PMC
October 2010

Diagnostic assay for Rickettsia japonica.

Emerg Infect Dis 2009 Dec;15(12):1994-7

National Institute of Infectious Diseases, Tokyo 162-8640, Japan.

We developed a specific and rapid detection system for Rickettsia japonica and R. heilongjiangensis, the causative agents of spotted fever, using a TaqMan minor groove binder probe for a particular open reading frame (ORF) identified by the R. japonica genome project. The target ORF was present only in R. japonica-related strains.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3044520PMC
http://dx.doi.org/10.3201/eid1512.090252DOI Listing
December 2009

A single circularly permuted GFP sensor for inositol-1,3,4,5-tetrakisphosphate based on a split PH domain.

Bioorg Med Chem 2009 Oct 13;17(20):7381-6. Epub 2009 Aug 13.

Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011, Japan.

A fluorescent sensor for the detection of inositol-1,3,4,5-tetrakisphosphate, Ins(1,3,4,5)P(4), was constructed from a split PH domain and a single circularly permuted GFP. A structure-based design was conducted to transduce a ligand-induced subtle structural perturbation of the split PH domain to an alteration in the population of the protonated and the deprotonated states of the GFP chromophore. Excitation of each distinct absorption band corresponding to the protonated or the deprotonated state of GFP resulted an increase and a decrease, respectively, in the intensity of emission spectra upon addition of Ins(1,3,4,5)P(4) to the split PH domain-based sensor. The Ins(1,3,4,5)P(4) sensor retained the ligand affinity and the selectivity of the parent PH domain, and realized the ratiometric fluorescence detection of Ins(1,3,4,5)P(4).
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http://dx.doi.org/10.1016/j.bmc.2009.08.015DOI Listing
October 2009

Shear bond strength of orthodontic brackets bonded with different self-etching adhesives.

Am J Orthod Dentofacial Orthop 2009 Sep;136(3):425-30

Professor, Department of Orthodontics, School of Dentistry, Dental Research Center (CIEAO), Autonomous University of the State of Mexico (UAEM), Toluca, Mexico.

Introduction: The purpose of this study was to compare the shear bond strength (SBS) of orthodontic brackets bonded with 4 self-etching adhesives.

Methods: A total of 175 extracted premolars were randomly divided into 5 groups (n = 35). Group I was the control, in which the enamel was etched with 37% phosphoric acid, and stainless steel brackets were bonded with Transbond XT (3M Unitek, Monrovia, Calif). In the remaining 4 groups, the enamel was conditioned with the following self-etching primers and adhesives: group II, Transbond Plus and Transbond XT (3M Unitek); group III, Clearfil Mega Bond FA and Kurasper F (Kuraray Medical, Tokyo, Japan); group IV, Primers A and B, and BeautyOrtho Bond (Shofu, Kyoto, Japan); and group V, AdheSE and Heliosit Orthodontic (Ivoclar Vivadent AG, Liechtenstein). The teeth were stored in distilled water at 37 degrees C for 24 hours and debonded with a universal testing machine. The adhesive remnant index (ARI) including enamel fracture score was also evaluated. Additionally, the conditioned enamel surfaces were observed under a scanning electron microscope.

Results: The SBS values of groups I (19.0 +/- 6.7 MPa) and II (16.6 +/- 7.3 MPa) were significantly higher than those of groups III (11.0 +/- 3.9 MPa), IV (10.1 +/- 3.7 MPa), and V (11.8 +/- 3.5 MPa). Fluoride-releasing adhesives (Kurasper F and BeautyOrtho Bond) showed clinically acceptable SBS values. Significant differences were found in the ARI and enamel fracture scores between groups I and II.

Conclusions: The 4 self-etching adhesives yielded SBS values higher than the bond strength (5.9 to 7.8 MPa) suggested for routine clinical treatment, indicating that orthodontic brackets can be successfully bonded with any of these self-etching adhesives.
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http://dx.doi.org/10.1016/j.ajodo.2007.08.024DOI Listing
September 2009

Surveillance, recognition, and reporting of Tsutsugamushi disease (scrub typhus) and Japanese spotted fever by general practice clinics in Miyazaki Prefecture, determined by questionnaire survey in 2007.

J Infect Chemother 2009 Aug 18;15(4):269-72. Epub 2009 Aug 18.

Infectious Disease Surveillance Center, National Institute of Infectious Diseases, Toyama 1-23-1, Shinjuku-ku, Tokyo, 162-8640, Japan.

In June 2007, a questionnaire survey related to the surveillance, recognition, and reporting of Tsutsugamushi disease (TD) and Japanese spotted fever (JSF)--diseases considered endemic in Miyazaki Prefecture--was distributed to general practice clinics in the prefecture. The response rate was 40.9% (232/567). While 75.5% of the responding clinics knew TD to be a notifiable disease, only 41.8% knew JSF was notifiable. The recognition level of JSF surveillance was lower in the low-incidence areas of JSF within Miyazaki Prefecture. In 2006, 25 cases were clinically suspected as TD by the responding clinics; of the 25 cases, 9 were confirmed and 8 of these were reported to the National Epidemiological Surveillance of Infectious Diseases (NESID). Only 1 of 6 clinically suspected JSF cases from the responding clinics was confirmed in 2006, and it was not reported to NESID. The clinics located in the high-incidence areas for TD tended not to perform laboratory confirmation of the clinically suspected cases of either of the diseases. Considering that NESID requires laboratory confirmation of the reported cases of these diseases, their extent may be underestimated, especially in the high-incidence areas. For clinics in Miyazaki Prefecture, we need to publicize the existence of JSF surveillance and inform clinics about the laboratories available for confirmation of JSF and TD in the prefecture.
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http://dx.doi.org/10.1007/s10156-009-0696-6DOI Listing
August 2009

Identification of an N-acetylcysteine conjugate in the urine after oral administration of 2,4-dichloro-1-nitrobenzene to rats.

J Toxicol Sci 2009 Apr;34(2):233-7

Oral administration of 2,4-dichloro-1-nitrobenzene (2,4-DCNB) causes kidney tumors in the rat. The objective of the present study was to identify the chemical structure of 2,4-DCNB metabolites in urine. Urine from 2,4-DCNB fed rats was more yellow than urine from control rats, exhibiting a broad UV-spectrum around a peak wavelength of 360 nm; the control urine did not have an absorbance. The yellow component was extracted and analyzed. The optical properties of the yellow component were the same as the N-acetylcysteine conjugate of 1,4-dichloro-2-nitrobenzene (1,4-DCNB): 1,4-DCNB is secreted in urine as an N-acetylcysteine conjugate. LC-MS/MS analyses of this yellow component demonstrated its chemical structure to be the N-acetylcysteine conjugate of 2,4-DCNB. Nuclear overhauser effect and LC-MS/MS analyses revealed the structural isomer of this 2,4-DCNB metabolite as N-acetyl-S-(5-chloro-2-nitrophenyl)-L-cysteine. We also discuss the possibility that the N-acetylcysteine conjugate identified in this study plays a role as a proximate carcinogen in the formation of kidney tumors.
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http://dx.doi.org/10.2131/jts.34.233DOI Listing
April 2009

Design and performance of a system for blood collection of rats under whole-body inhalation exposure.

J Toxicol Sci 2009 Apr;34(2):221-6

In order to obtain basic risk assessment data on human health exposure to volatile organic compound (VOC) vapor by inhalation, a whole-body inhalation exposure system which allows blood collection during the exposure period was designed. The system was tested using chloroform as a model VOC. Chloroform vapor, sampled from the supply-header, animal-chambers and exhaust-header, remained constant in this system with variations in its concentration being less than 2%; flow rate of the vapor through the system was also constant. Rats were exposed to chloroform vapor and blood collected from the tail during exposure to the chloroform vapor. The chloroform concentration in the blood increased during the initial 60 min of exposure, and afterwards its concentration remained at about 2 microg/ml from 60 to 360 min. In conclusion, our design allows blood to be collected from individual rats during exposure by inhalation to test VOCs and changes in the blood concentration of the VOC during exposure to be assessed.
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http://dx.doi.org/10.2131/jts.34.221DOI Listing
April 2009

Quantitative analysis of fecal sapovirus shedding: identification of nucleotide substitutions in the capsid protein during prolonged excretion.

Arch Virol 2009 20;154(4):689-93. Epub 2009 Mar 20.

Miyazaki Prefectural Institute for Public Health and Environment, Japan.

Sapovirus (SaV) is an important pathogen causing gastroenteritis in humans. Quantitative analysis of the viral loads in feces collected from two SaV outbreaks was performed. Our results showed that SaV excretion generally decreased to an undetectable level in 2 weeks; however, some individuals excrete SaV in feces at high concentrations for 2-4 weeks after the onset of illness. In addition, we identified for the first time nucleotide changes in the capsid region during prolonged excretion.
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http://dx.doi.org/10.1007/s00705-009-0358-0DOI Listing
April 2009

Investigation of reservoir animals of Leptospira in the northern part of Miyazaki Prefecture.

Jpn J Infect Dis 2008 Nov;61(6):465-8

Department of Bacteriology, National Institute of Infectious Diseases, Tokyo, Japan.

We surveyed reservoir animals of leptospires in the northern part of Miyazaki Prefecture, where a cluster of human leptospirosis had occurred during the summer of 2006. Leptospira was isolated from 6 of 57 large Japanese field mice (Apodemus speciosus). The serogroups of the isolates were Autumnalis (5 strains) and Hebdomadis (1 strain) and the partial nucleotide sequences of their flaB genes suggested that the isolates belonged to L. interrogans. The human patient sera reacted specifically with the Leptospira strain isolated from the mice captured around the area where each patient occurred, suggesting that mice are the source of human infection. We also detected leptospiral DNAs by flaB-polymerase chain reaction in the kidneys of large feral animals; wild boars (positive ratio 10.3%; 4 of 39) and deer (19.2%; 10 of 52). The Leptospira spp. harbored by these animals were deduced to be L. interrogans (in 5 animals) and L. borgpetersenii (in 9 animals) by the nucleotide sequences of the amplicons. Anti-Leptospira antibodies were also detected among symptomatic hound dogs. These results suggest that these feral animals may cause leptospirosis and pose a potential risk to hunters and workers in the meat processing industry.
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November 2008

Occurrence of two different types of glutathione S-transferase placental form-positive hepatocytes after a single administration of 2,3,7,8-tetrabromodibenzo-p-dioxin in rats.

Ind Health 2008 Jul;46(3):281-8

Japan Bioassay Research Center, Japan Industrial Safety and Health Association, 2445 Hirasawa, Hadano, Kanagawa 257-0015, Japan.

Occurrence of glutathione S-transferase placental form (GST-P)-positive hepatocytes was examined, using 15 Wistar rats of both sexes each orally administered 2,3,7,8-tetrabromo-dibenzo-p-dioxin (TBDD) by gavage at a single dose of 0, 10, 30, 100 or 300 microg/kg body weight. Liver tissues were stained with anti-GST-P antibody. Two different types of GST-P-positive hepatocytes were found in the TBDD-dosed rat. One type was of the hepatocytes stained homogeneously with anti-GST-P antibody and clearly distinguishable from the surrounding normal tissue. The foci were composed of 2 to 60 hepatocytes exhibiting morphologically focal and clonal proliferation. The GST-P-positive hepatocellular foci occurred at two higher dose levels and only on Day 36 after the single administration. Another type was of the area occupied by the positively but heterogeneously stained hepatocytes appearing predominantly in the centrilobular region, at lower dose levels and persistently on Day 2 through 36. The stained hepatocytes appeared to be neither focally nor clonally proliferating. Females were more susceptible to formation of the two differently stained hepatocytes than males. It is suggested that the GST-P-positive foci represent an early stage of hepatocarcinogenesis, while the GST-P-positive area is associated with the induction of detoxifying Phase II GSTs.
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http://dx.doi.org/10.2486/indhealth.46.281DOI Listing
July 2008

Inhalation carcinogenicity and chronic toxicity of carbon tetrachloride in rats and mice.

Inhal Toxicol 2007 Oct;19(13):1089-103

Japan Bioassay Research Center, Japan Industrial Safety and Health Association, Hadano, Kanagawa, Japan.

Carcinogenicity and chronic toxicity of carbon tetrachloride were examined by inhalation exposure of 50 F344 rats and 50 BDF1 mice of both sexes to carbon tetrachloride at 0 (clean air), 5, 25, or 125 ppm (v/v) for 6 h/day, 5 days/wk, for 104 wk. Incidences of hepatocellular adenomas and carcinomas in rats and mice of both sexes and of adrenal pheochromocytomas in mice of both sexes were significantly increased dose-dependently. Hepatocellular carcinomas and cirrhosis significantly occurred in the 125-ppm-exposed rats of both sexes, and 3 cases of hepatocellular carcinomas and increased incidences of hepatic altered cell foci were noted in the 25-ppm-exposed female rats. Hepatocellular carcinomas were induced in mice of both sexes at 25 and 125 ppm, and hepatocellular adenomas occurred in females at 5 ppm without any degenerative or necrotic change in hepatocytes. Hepatocellular carcinomas metastasized to the lung. The chronic hepatotoxicity was characterized by cirrhosis, fibrosis, and fatty change in rats, and ceroid deposition, bile-duct proliferation, and hydropic change in mice. Survival rates were decreased in the 125-ppm-exposed rats and mice of both sexes and in the 25-ppm-exposed female mice, in association with decreased body weights. The decreased survival rates were considered to be causally related to both various tumors including hepatocellular carcinomas and severe chronic progressive nephropathy in rats and to hepatocellular carcinomas in mice. This study provided clear evidence of carcinogenicity for carbon tetrachloride in rats and mice. A cytotoxic-proliferative and genotoxic mode of action for carbon tetrachloride-induced hepatocarcinogenesis was suggested.
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http://dx.doi.org/10.1080/08958370701628770DOI Listing
October 2007

Thirteen-week inhalation toxicity of carbon tetrachloride in rats and mice.

J Occup Health 2007 Jul;49(4):249-59

Japan Bioassay Research Center, Japan Industrial Safety and Health Association, Kanagawa, Japan.

Subchronic toxicity of carbon tetrachloride (CCl4) was examined by inhalation exposure of F344 rats and BDF1 mice of both sexes to 0, 10, 30, 90, 270 or 810 ppm (v/v) CCl4 vapor for 13 wk (6 h/d and 5 d/wk). In the high exposure levels at 270 and 810 ppm, altered cell foci in the livers of both rats and mice, and fibrosis and cirrhosis in the rat liver were observed. Hematoxylin and eosin-stained altered cell foci of rats were recognized as glutathione-S-transferase placental form (GST-P) positive foci, which are preneoplastic lesions of hepatocarcinogenesis. The most sensitive endpoint of CCl4-induced toxicity was fatty change with large droplets in rats of both sexes and male mice, and cytoplasmic globules in male mice, as well as increased relative liver weight in male rats. Those endpoints were manifested at 10 ppm and the LOAEL was determined as 10 ppm for the hepatic endpoints in rats and mice. Enhanced cytolytic release of liver transaminases into plasma in rats and mice and its close association with hepatic collapse in mice were observed at medium and high levels of inhalation exposure. Both CCl4-induced hematotoxicity and nephrotoxicity were observed in both rats and mice, but those toxicities were manifested at higher exposure concentrations than hepatotoxicity. The LOAEL for the hepatic endpoint and the GST-P-stained altered cell foci provide relevant animal data for reconsidering the occupational exposure limit val1ue of 5 ppm for CCl4 and strengthen the evidence of CCl4-induced hepatocarcinogenicity which is used in its carcinogenicity classification.
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http://dx.doi.org/10.1539/joh.49.249DOI Listing
July 2007

Shear bond strength of a new fluoride-releasing orthodontic adhesive.

Dent Mater J 2007 Jan;26(1):45-51

Department of Prosthodontics, Division of Oral Functional Science and Rehabilitation, School of Dentistry, Asahi University, 1851 Hozumi, Mizuho City, Gifu 501-0296, Japan.

This study evaluated the shear bond strength of stainless steel brackets bonded to enamel with a new fluoride-releasing orthodontic adhesive system. A total of 140 extracted human bicuspids were randomly divided into four groups. Group I (Transbond XT) was a control group in which enamel was etched with phosphoric acid. For the remaining groups, enamel was conditioned with a self-etching primer (SEP): Group II (Transbond Plus), Group III (BeautyOrtho Bond), and Group IV (BeautyOrtho Bond + Salivatect). Stainless steel brackets were bonded to all tooth samples. After which, the samples were stored, thermocycled, tested, and statistically analyzed. Besides bond strength evaluation, the adhesive remnant index (ARI) was also evaluated. The shear bond strengths of Groups II, III, and IV were significantly lower than Group I, and Group II was significantly greater than that of Group III. Concerning ARI scores, no significant differences were found between the groups. Further, no enamel fracture was observed during shear bond test with the new SEP. In conclusion, when enamel was conditioned with the new SEP, the mean values of shear bond strength yielded were lower than when it was etched with 37% phosphoric acid. Nonetheless, these mean values were higher than the average suggested by Reynolds as optimum for clinical treatment.
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http://dx.doi.org/10.4012/dmj.26.45DOI Listing
January 2007

Dose- and time-dependent effects of 2,3,7,8-tetrabromodibenzo-p-dioxin on rat liver.

J Toxicol Sci 2007 Feb;32(1):47-56

Japan Bioassay Research Center, Japan Industrial Safety and Health Association, 2445 Hirasawa, Hadano, Kanagawa 257-0015, Japan.

Dose- and time-dependent effects of 2,3,7,8-tetrabromodibenzo-p-dioxin (TBDD) on the liver were examined by single administration of TBDD by gavage to male and female rats. Fifteen Wistar rats of each sex per group received 0, 10, 30, 100 or 300 microg TBDD/kg body weight. Rats surviving to scheduled necropsy on Day 2, 7 or 36 after the TBDD administration were examined for hepatic histopathology, activities of hepatic microsomal enzymes and serum levels of lipids, total cholesterol and transaminases and hepatic concentrations of TBDD. Tigroid basophilic cytoplasm and hepatocellular hypertrophy were observed at 10 microg/kg on Day 2 or 7 through 36, whereas degenerative and aggressive lesions such as necrosis, fibrosis, multinucleated hepatocytes and disarrangement of hepatocytes occurred later at higher dose levels. Persistently increased activities of hepatic aryl hydrocarbon hydroxylase (AHH), ethoxycoumarin O-deethylase (ECOD) and ethoxyresorufin O-deethylase (EROD), increased serum levels of total cholesterol and phospholipid and increased relative liver weight were observed in all groups dosed 10 mug/kg and above, suggesting that hepatic microsomal monooxygenases and basophilic cytoplasm of hepatocytes were early and sensitive indicators among those TBDD-induced effects. A dose-dependent increase in liver concentrations of TBDD on Day 2 was followed by logarithmic decreases in TBDD concentrations against the days elapsed after the TBDD administration. An elimination half-life (t(1/2)) of TBDD from the liver was estimated to range from 12 to 16 days. It was suggested that females were more susceptible to TBDD than males, and that acute hepatotoxicity of TBDD was as potent as that of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD).
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http://dx.doi.org/10.2131/jts.32.47DOI Listing
February 2007

Annual incidence of tsutsugamushi disease in Miyazaki prefecture, Japan in 2001-2005.

Jpn J Infect Dis 2006 Dec;59(6):404-5

Miyazaki Prefectural Institute for Public Health and Environment, Miyazaki 889-2155, Japan.

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December 2006