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Tsuyoshi Yamaguchi

Publications and source records attributed to Tsuyoshi Yamaguchi.

At least 19 recordsLinked to original sources
PubMed2006

4'-Fluorinated carbocyclic nucleosides: synthesis and inhibitory activity against S-adenosyl-L-homocysteine hydrolase.

4'-Fluorinated analogue of 9-[(1'R,2'S,3'R)-2',3'-dihydroxy-cyclopentan-1'-yl]adenine (DHCaA) and their related analogues were systematically synthesized under the Mitsunobu and palladium(0) coupling conditions followed by fluorination with inversion of the configuration by using diethylaminosulfur trifluoride, respectively. 4'-beta-Fluoro DHCaA and 2-amino-4'-alpha-fluoro DHCaA demonstrated slight inhibitory activity against human and Plasmodium falciparum S-adenosyl-L-homocysteine hydrolase, respectively.

Adenosine↗
PubMed2006

Photocatalytic oxidation of propylene with molecular oxygen over highly dispersed titanium, vanadium, and chromium oxides on silica.

Photocatalytic oxidation of propylene with molecular oxygen at room temperature was investigated over various silica-supported metal oxides with low loading. The photocatalytic active site is assumed to be the isolated tetrahedrally coordinated metal oxides in the ligand-to-metal charge-transferred state, such as (Mdelta- -OLdelta+). Photocatalytic epoxidation of propylene into propylene oxide was promoted over silica-supported V and Ti oxides at steady state. Over silica-supported Cr oxide, the propylene oxide formation rate was remarkably decreased with the time course in the reaction. The oxidation state and the coordination environment of the supported Ti, V, and Cr oxide species were determined by diffuse reflectance UV-vis spectroscopy (DRS) and electron spin resonance (ESR). During the photocatalytic oxidation, the oxidation state of the Ti4+ species was not varied. On the other hand, the V5+ species was partially reduced to V4+ and the Cr6+ species was successively reduced to Cr5+ and Cr3+. An isotopic tracer study of the C3H6-18O2 reaction suggests the difference of the active oxygen species between TiO2/SiO2 and V2O5/SiO2. The active oxygen species on TiO2/SiO2 is derived from molecular oxygen. On the other hand, the photogenerated products on V2O5/SiO2 incorporate the lattice oxygen of the surface metal oxide species. It is suggested that the kinds of terminal ligand (hydroxyl or oxo) of the tetrahedrally coordinated metal oxides on silica decide the active oxygen species in the photocatalytic oxidation. A photoinduced hole center on the monohydroxyl (SiO)3Ti-OH species activates molecular oxygen that reacts with propylene. In the case of the monooxo (SiO)3V=O and dioxo (SiO)2Cr=O2 species, the photoactivated lattice oxygen (OL-) directly reacts with propylene.

Alkenes↗
PubMed2006

Genetic diversity and epizootiology of Chlamydophila psittaci prevalent among the captive and feral avian species based on VD2 region of ompA gene.

To study genetic diversity and occurrence of Chlamydophila psittaci, a total of 1,147 samples from 11 avian orders including 53 genera and 113 species of feral and captive birds were examined using ompA gene based nested PCR. Three types of chlamydiae: C. psittaci (94.12%), C. abortus (4.41%) and unknown Chlamydophila sp. (1.47%) were identified among 68 (5.93%) positive samples (Psittaciformes-59, Ciconiiformes-8 and Passeriformes-1). Based on nucleotide sequence variations in the VD2 region of ompA gene, all 64 detected C. psittaci strains were grouped into 4 genetic clusters. Clusters I, II, III and IV were detected from 57.35%, 19.12%, 10.29% and 7.35% samples respectively. A single strain of unknown Chlamydophila sp. was found phylogenetically intermediate between Chlamydophila species infecting avian and mammalian hosts. Among Psittaciformes, 28 out of 81 tested species including 10 species previously unreported were found to be chlamydiae positive. Chlamydiosis was detected among 8.97% sick and 48.39% dead birds as well 4.43% clinically normal birds. Therefore, it was observed that though various genetically diverse chlamydiae may cause avian chlamydiosis, only a few C. psittaci strains are highly prevalent and frequently associated with clinical/subclinical infections.

Amino Acid Sequence↗
PubMed2006

A survey of avian polyomavirus (APV) infection in imported and domestic bred psittacine birds in Japan.

Although birds infected with avian polyomavirus (APV) subclinically could be a source of infection, no epidemiological studies of APV in psittacine birds have been reported in Japan. In the present study, we investigated subclinical morbidity rate of APV in imported and domestically bred psittacine birds by polymerase chain reaction (PCR). Of 402 live birds from which blood or feather samples were taken between April, 2003 and March, 2004, 11 (2.7%) were found to be APV positive. The DNA sequences of the APV t/T antigen region were determined for five APV-positive randomly selected samples and were found to be conserved.

Animals↗
PubMed2005

Transcriptional regulation of neuronal genes and its effect on neural functions: transcriptional regulation of neuropeptide Y gene by leptin and its effect on feeding.

Leptin is an adipose tissue-derived secretory hormone that suppresses appetite by inhibition of neuropepeptide Y (NPY) gene expression in arcuate nucleus (ARC) in the hypothalamus. To investigate the transcriptional regulation of NPY gene by leptin, we carried out a luciferase assay using NPY gene promotor plasmid (NPY-luc) in NPY expressing cells such as N18TG2, NG108-15, and PC12 cells. In these cells, the NPY gene was transactivated by leptin through activation of leptin receptor. Leptin-induced transactivation was mediated through the 221-bp region of the NPY gene promotor, which possesses two putative STAT3 binding sites. To investigate the mechanism of in vivo suppression of NPY gene transcription in ARC by leptin, the effect of SOCS members on the leptin-induced transactivation of NPY gene was studied. In vivo SOCS2 and SOCS3 mRNAs were induced in mouse hypothalamus by leptin. Although leptin (125 ng/ml) induced significant increase in NPY gene transcriptional activity in mock-transfected cells, the leptin-induced NPY gene transcriptional activity was completely abolished in SOCS3-transfected cells. SOCS3 also suppressed the basal NPY gene transcription. These finding suggested that leptin inhibits NPY gene transcription in the hypothalamus in vivo and SOCS3 is a negative regulator of the NPY gene.

Animals↗
PubMed2005

Site-site memory equation approach in study of density/pressure dependence of translational diffusion coefficient and rotational relaxation time of polar molecular solutions: acetonitrile in water, methanol in water, and methanol in acetonitrile.

We present results of the theoretical study and numerical calculation of the dynamics of molecular liquids based on the combination of the memory equation formalism and the reference interaction site model (RISM). Memory equations for the site-site intermediate scattering functions are studied in the mode-coupling approximation for the first-order memory kernels, while equilibrium properties such as site-site static structure factors are deduced from RISM. The results include the temperature-density (pressure) dependence of translational diffusion coefficients D and orientational relaxation times tau for acetonitrile in water, methanol in water, and methanol in acetonitrile--all in the limit of infinite dilution. Calculations are performed over the range of temperatures and densities employing the extended simple point charge model for water and optimized site-site potentials for acetonitrile and methanol. The theory is able to reproduce qualitatively all main features of temperature and density dependences of D and tau observed in real and computer experiments. In particular, anomalous behavior, i.e, the increase in mobility with density, is observed for D and tau of methanol in water, while acetonitrile in water and methanol in acetonitrile do not show deviations from the ordinary behavior. The variety exhibited by the different solute-solvent systems in the density dependence of the mobility is interpreted in terms of the two competing origins of friction, which interplay with each other as density increases: the collisional and dielectric frictions which, respectively, increase and decrease with increasing density.

Journal Article↗
PubMed2005

Disruption of erythrocytes distinguishes fixed cells/tissues from viable cells/tissues following microwave coagulation therapy.

Microwave coagulation therapy (MCT) has recently been applied to treat hepatic tumors. However, the histological changes in the liver following MCT have not been fully elucidated. A type of cell death known as microwave fixation has been reported in areas adjacent to the microwave irradiator electrodes, and these areas are without acid phosphatase (AcP) activity. Diagnosis of microwave-fixed tissue by hematoxylin and eosin (HE) staining is very difficult because morphology is well maintained for months. In an effort to clarify the histological changes and the mechanisms of microwave fixation, we performed HE staining, enzyme histochemistry for AcP, and electron microscopy in both rat and human liver samples after MCT. Although the microwave-fixed tissues maintained their structure on HE staining, membranes of microwave-fixed cells were seriously damaged and there were no apparent organelle structures in these cells on electron microscopy. Erythrocytes were also damaged in these tissues on both light and electron microscopy. The cause of microwave fixation is thought to be injury of the membrane, which is similar to coagulative necrosis. In conclusion, microwave fixation can be considered a type of coagulative necrosis without enzyme digestion. Disruption of erythrocytes on HE staining is an interesting and important diagnostic clue in distinguishing nonviable fixed tissues from viable tissues following MCT.

Acid Phosphatase↗
PubMed2005

Natural recombinant between equine herpesviruses 1 and 4 in the ICP4 gene.

Equine herpesvirus 1 (EHV-1) is a pathogen causing rhinopneumonia in young horses, abortion in mares, and myeloencephalitis in adult horses. Two types, EHV-1 P and EHV-1 B, have recently been dominant among 16 electropherotypes. EHV-1 P and EHV-1 B viruses were compared by long and accurate polymerase chain reaction (LA-PCR) and restriction fragment length polymorphism (RFLP) analysis. Differences in restriction sites were found to be focused in ORF64, which encodes the infected cell protein 4 (ICP4), and downstream of the ICP4 gene. The 3 ' -end and downstream of ICP4 gene of EHV-1 B were found to be replaced by the corresponding region of EHV-4, indicating that EHV-1 B is a naturally occurring recombinant virus between progenitors of EHV-1 P and EHV-4. This is the first report showing a natural interspecies recombinant in alphaherpesviruses.

Animals↗
PubMed2005

Duplex shuttle PCR for differential diagnosis of budgerigar fledgling disease and psittacine beak and feather disease.

Two common viral diseases in psittacine birds including budgerigar fledgling disease (BFD), generally called avian polyomavirus (APV) infection, and psittacine beak and feather disease (PBFD) have similar clinical manifestations characterized by feather disorders. A duplex shuttle PCR was developed for detection of APV and PBFD virus (PBFDV). Two pairs of oligonucleotide primers were designed to amplify a 298-bp fragment of the t/T antigen region of APV genome and a 495-bp fragment of the capsid protein region encoded by open reading frame (ORF) C1 of PBFDV genome, respectively. In the present study, APV and PBFDV were detected simultaneously in one tube by duplex shuttle PCR using these two pairs of primers. The detection limits were 2 viral copies of APV and 3 viral copies of PBFDV. In the clinical application, we detected 16 APV-positive, 15 PBFDV-positive, and 3 mixed infected samples in 39 samples examined. Sequences of the amplified products were read. The t/T antigen region was conserved in the APV-positive samples as expected. ORF C1 of PBFDV genome showed diversity. Phylogenic analysis indicated that PBFDV ORF C1 consisted of 6 clusters which were related to subfamilies of psittacine birds. Our duplex shuttle PCR could be a useful method for differential diagnosis and molecular epidemiology of BFD and PBFD.

Animals↗
PubMed2005

Identification and characterization of an immunodominant 28-kilodalton Coxiella burnetii outer membrane protein specific to isolates associated with acute disease.

Coxiella burnetii causes acute Q fever in humans and occasional chronic infections that typically manifest as endocarditis or hepatitis. Isolates associated with acute disease were found to be distinct from a group of chronic disease isolates by a variety of biochemical parameters and in a guinea pig fever model of acute disease, suggesting a difference in virulence potential. We compared antigenic polypeptides among C. burnetii isolates and found an immunodominant 28-kDa protein in acute group isolates but not in chronic group isolates (T. Ho, A. Hotta, G. Q. Zhang, S. V. Nguyen, M. Ogawa, T. Yamaguchi, H. Fukushi, and K. Hirai, Microbiol. Immunol. 42:81-85, 1998). In order to clone the adaA gene, the N-terminal amino acid sequence of adaA was determined and a 59-bp fragment was amplified from Nine Mile phase I DNA by PCR. The putative gene fragment was used to screen a lambda ZAP II genomic DNA library, and an open reading frame expressing a 28-kDa immunoreactive protein was identified. Sequence analysis predicted a gene encoding an approximately 28-kDa mature protein with a typical signal sequence. The adaA (acute disease antigen A) gene was detected in acute group C. burnetii isolates but not identified in chronic group isolates by PCR and Southern blotting. A typical signal peptide was predicted in adaA, and specific antibody to adaA reacted with the purified membrane fraction of acute group isolates by Western blotting, suggesting that adaA is exposed on the outer surface of C. burnetii. adaA was overexpressed in pET23a as a fusion protein in Escherichia coli to develop anti-recombinant adaA (anti-radaA) specific antibody, which recognized a approximately 28-kDa band in acute group isolates but not in chronic group isolates. In addition, immunoblotting indicates that radaA reacted with sera derived from animals infected with acute group isolates but did not react with sera from animals infected with chronic group isolates. These results support the idea that an adaA gene-targeted PCR assay and an radaA antigen-based serodiagnostic test may be useful for differential diagnosis of acute and chronic Q fever.

Acute Disease↗
PubMed2005

Detection of novel gammaherpesviruses in wild animals of South Africa.

Herpesviral DNA was detected in 24/261 DNA samples that were extracted from whole blood of 13 wild animal species in South Africa. Herpesviral DNA was shown in 22 impalas (Aepyceros melampus) and 2 springboks (Antidorcas marsupialis). All of DNA sequences detected in impalas were identical, whereas two DNA sequences detected in springboks were different each other. These three sequences showed 44 to 72% homology to the corresponding gene of the Gammaherpesvirinae, indicating that these three viruses should be unrecognized novel gammaherpesviruses. The putative novel herpesviruses were tentatively designated as Aepyceros melampus (impala) herpesvirus 1 (ImHV-1), Antidorcas marsupialis (springbok) herpesviruses 1 (SpHV-1) and 2 (SpHV-2). ImHV-1 seems to be a relatively independent virus. SpHV-1 belongs to a group of ruminant lymphotropic herpesviruses and SpHV-2 is closer to a malignant catarrhal fever virus group. Potential threat of these herpesviruses to domestic animals should be considered.

Amino Acid Sequence↗
PubMed2004

In vitro susceptibility to tetracycline and fluoroquinolones of Japanese isolates of Coxiella burnetii.

Coxiella burnetii is the agent of the worldwide zoonosis, Q fever. The in vitro susceptibility to tetracycline and fluoroquinolones of Japanese isolates of C. burnetii was evaluated for the first time. The MICs against Japanese isolates were almost the same as the MICs against the foreign reference isolates. The results suggest that the common antibiotics therapy for Q fever used in other countries is also effective for Japanese Q fever patients.

Anti-Bacterial Agents↗
PubMed2004

Growth and virulence alterations of equine herpesvirus 1 by insertion of a green fluorescent protein gene in the intergenic region between ORFs 62 and 63.

Nucleotide sequences of the intergenic region between ORF 62 and ORF 63 of equine herpesvirus 1 (EHV-1) isolates were analyzed. The sequences of this region consisted of variable and conserved domains among EHV-1 isolates. An EHV-1 mutant, Ab4-GFP, was constructed by inserting a green fluorescent protein (GFP) expression cassette flanked by lox P at both ends into the intergenic region between ORF 62 and ORF 63. Another mutant, Ab4-loxP, which contains one lox P site, was constructed by excision of the GFP cassette from the Ab4-GFP virus genome by cre enzyme. The recombinant Ab4-GFP formed smaller plaques than the wild type in MDBK cells. Virus production also decreased for Ab4-GFP in multistep growth analyses. Virulence of Ab4-GFP in both mice and hamsters was weaker than that of the wild type. Ab4-loxP exhibited properties similar to those of the wild type. These results suggest that the intergenic region between ORF 62 and ORF 63 plays various roles in the virus growth.

Animals↗
PubMed2004

Comparison of Japanese isolates of Coxiella burnetii by PCR-RFLP and sequence analysis.

The genetic variation of Japanese isolates of Coxiella burnetii, the agent of Q fever, was found for the first time. Forty-nine out of 72 isolates had the chronic pattern of the isocitrate hydrogenase gene. Sequence analysis revealed that the isolates have a specific nucleotide sequence. The putative amino acid sequence was the same as that of chronic reference strains. These results suggest the variation of C. burnetii isolates in Japan.

Amino Acid Sequence↗
PubMed2004

Use of monoclonal antibodies for analyses of Coxiella burnetii major antigens.

Monoclonal antibodies (MAbs) to major antigens of Coxiella burnetii were produced. Some of the MAbs to a 62-kDa protein antigen, peptidoglycan protein complex and lipopolysaccharide (LPS) O-chains reacted with other bacteria whereas none of the MAbs to outer membrane proteins and LPS outer-core did. The LPS outer-core and OMPs may be useful antigens for specifically detecting antibodies to C. burnetii.

Antibodies, Bacterial↗
PubMed2004

Leucocytozoon lovati infections in wild rock ptarmigan (Lagopus mutus) in Japan.

Leucocytozoon lovati infections were detected in free-flying rock ptarmigan (Lagopus mutus), an endangered species that inhabits alpine areas in Japan. Eight of nine adult birds tested positive for L. lovati infection. For comparison, two captive rock ptarmigans hatched in a breeding facility at the foot of the mountains were examined. Both were negative for L. lovati infection. This is the first report of L. lovati infection in the rock ptarmigan in Japan.

Animals↗
PubMed2003

Leptin-induced transactivation of NPY gene promoter mediated by JAK1, JAK2 and STAT3 in the neural cell lines.

Neuropeptide Y (NPY) plays an important role in the central and sympathetic regulation of food intake and blood pressure. Although the NPY gene expression is regulated by a number of agents such as leptin, the mechanism responsible for leptin-induced regulation of the transcription of the NPY gene remains to be explored. In this study, the NPY gene promoter was transactivated by leptin in N18TG2, NG108-15 and PC12 cells which expressed the functional leptin receptor. The long isoform of leptin receptor (OB-Rb) could induce the transactivation, but the C-terminal truncated form (OB-Ra) could not. When dominant negative type of STAT3, JAK1 or JAK2 and was co-expressed, the leptin-induced transactivation was suppressed almost completely. The leptin-response element which confers NPY gene transactivation by leptin was determined in the 221-bp region of rat NPY gene promoter (-553/-335), where two STAT3-binding site-like elements (TCCAGTA) exist. These results indicated that activation of JAK1, JAK2 and STAT3 is necessary for leptin-induced transactivation of NPY gene through the leptin-response element in these neural cells.

Animals↗