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Tsuyoshi Yamaguchi

Publications and source records attributed to Tsuyoshi Yamaguchi.

27 records · Page 2Linked to original sources
PubMed2003

SCID mouse model for lethal Q fever.

Q fever, a worldwide zoonosis caused by Coxiella burnetii, has many manifestations in humans. Endocarditis is the most serious complication of Q fever. Animal models are limited to acute pulmonary or hepatic disease and reproductive disorders. An appropriate experimental animal model for Q fever endocarditis does not yet exist. In this study, severe combined immunodeficient (SCID) mice infected with C. burnetii showed persistent clinical symptoms and died, whereas immunocompetent mice similarly infected became asymptomatic and survived. The SCID mice examined in this study had severe chronic lesions in their primary organs: the heart, lung, spleen, liver, and kidney. The heart lesions of the SCID mice were similar to those in humans with chronic Q fever endocarditis: they had focal calcification and expanded macrophages containing C. burnetii. The 50% lethal dose of C. burnetii in SCID mice was at least 10(8) times less than that in immunocompetent mice. The SCID mouse is highly susceptible to C. burnetii, and the immunodeficiency of the host enhances the severity of Q fever. This animal model could provide a new tool for the study of chronic Q fever and Q fever in immunodeficient hosts.

Animals↗
PubMed2003

Neuropeptide Y-induced contraction and its desensitization through the neuropeptide Y receptor subtype in several rat veins.

Exogenous neuropeptide Y produced marked contractions in rat isolated common jugular, brachial, and caudal veins, while it produced little or no contractions in common carotid, brachial, and caudal arteries. Neuropeptide Y (30 nM) produced larger contractions in these veins than did phenylephrine (1 microM), with maximal contractions through the neuropeptide Y receptor and the alpha1-adrenoceptor, respectively. In contrast, neuropeptide Y (30 nM) produced smaller contractions than did phenylephrine (1 microM) in the arteries. Pre-treatment with neuropeptide Y (30 nM) showed remarkable desensitization to neuropeptide Y (30 nM). This desensitization lasted for 1 h in the caudal vein or for 2 h in the common carotid and brachial veins. The neuropeptide Y-induced contraction and its desensitization probably occurred through the neuropeptide Y receptor subtype Y1, because only the neuropeptide Y receptor subtype Y1 was detected in the smooth muscle by the reverse transcriptase-polymerase chain reaction.

Animals↗
PubMed2002

Lack of inhibitory effects of green tea catechins in 1,2-dimetylhydrazine-induced rat intestinal carcinogenesis model: comparison of the different formulations, administration routes and doses.

Differences in the modifying effects of green tea catechins (GTC) on intestinal carcinogenesis by different formulations, doses and administration routes were investigated in male rats pretreated with 1,2-dimethylhydrazine (DMH). One hundred and eighty nine F344 male rats received subcutaneous injections of DMH at 40 mg/kg body weight twice a week for 3 weeks. Three days after completion of the carcinogen treatment, they were divided into nine groups. Each was administered a different source of 0.1% or 0.01% of GTC (Mitsui Norin Co. (M) or Taiyo Kagaku Co. (T)) either in the diet (D) or the drinking water (W), or basal diet and tap water alone without GTC for 33 weeks and then killed for autopsy. The survival rate tended to be lower with 0.01% MGTC (W) group than in the other groups. In the large intestine, although the multiplicity and/or incidences of adenomas showed tendencies for dose-dependent decrease in all GTC groups, and the average volumes of tumors tended to be decrease dose-dependently in the MGTC (W) and TGTC (W) groups, the multiplicity of carcinomas did not show such a trend, rather being significantly increased in the 0.01% MGTC (D) and 0.1% TGTC (W) groups. In the small intestine, the incidence and the multiplicity of tumors in all GTC treated groups had a tendency to decrease. On the other hand, the volume of tumors was increased with statistical significance in the 0.01% MGTC (W) and 0.1% TGTC (W) groups. Thus it can be concluded that GTC does not exert chemopreventive effects on intestinal carcinogenesis irrespective of its formulation, dose or route of administration.

1,2-Dimethylhydrazine↗
PubMed2002

Marked neuropeptide Y-induced contractions via NPY-Y1 receptor and its desensitization in rat veins.

The aim of this study was to investigate neuropeptide Y (NPY)-induced vasoconstrictions in rat blood vessels and which NPY receptor subtype is involved in vasoconstrictions. NPY produced marked contractions in rat common jugular, brachial, portal, femoral and tail veins, and vena cava inferior, whereas it produced little or no contractions in rat common carotid, brachial, femoral and tail arteries, and thoracic and abdominal aortae. The maximal NPY-induced contractions were larger than maximal phenylephrine (PE)-induced contractions in the veins. These NPY-induced contractions were blocked by the Y1 antagonists, SRL-21, and BIBP3226 but not by the Y5 antagonist, L-152804. A Y2 agonist, NPY (13-36), did not produce contractions. RT-PCR showed that NPY-Y1 was the only receptor subtype in the veins indicating that NPY-induced contractions are mediated through the Y1 receptor. Pretreatment with NPY showed a rapid and long-lasting desensitization of these contractions. The marked NPY-induced contractions and its desensitization in the veins suggest the physiological relevance of NPY in the venous circulation.

Algorithms↗
PubMed2002

Synthesis of noraristeromycin analogues possessing SAH hydrolase inhibitory activity for the development of antimalaria agents.

Noraristeromycin analogues such as 3',4'-anhydronoraristeromycins, 2-amino-3',4'-anhydronoraristeromycin and N6-cyclopropylnoraristeromycin were synthesized and their inhibitory activity against human and Plasmodium falciparum (P. falciparum) recombinant SAH hydrolase was investigated. Among them, 3',4'-anhydronoraristeromycin showed inhibitory activity against human recombinant S-adenosyl-L-homocysteine hydrolase (Ki = 12.4 microM, Kinact = 0.55 min-1).

Adenosine↗
PubMed2002

Phase variation analysis of Coxiella burnetii during serial passage in cell culture by use of monoclonal antibodies.

Antigenic changes in Coxiella burnetii Nine Mile strain phase I during serial passages in cell culture were analyzed with three groups of monoclonal antibodies (MAbs) against lipopolysaccharide. The MAbs of group 1 did not react with organisms that were passaged over five times, and the MAbs of group 2 did not react with organisms that were passaged over eight times. The MAbs of group 3 reacted with organisms passaged up to 15 times but did not react with phase II cells. These results suggest that C. burnetii could be differentiated into four phase states during phase variation.

Animals↗
PubMed2002

Incidence of Salmonella infection in healthy dogs in Gifu Prefecture, Japan.

A total of 1,013 feces samples and 8 mesenteric lymphonodus samples obtained from apparently healthy dogs were examined for the incidence of salmonella infection. One strain of S. typhimurium (ST) was isolated from feces of one dog, and S. enteritidis (SE) was isolated from the mesenteric lymphonodus of one dog. Sera obtained from 330 apparently healthy dogs were examined for Salmonella antibodies using an ELISA with heated whole cells of SE and ST. Fifty-one of the 330 serum samples were considered to be positive for salmonella antibodies, including 12 which were SE-positive and 39 which were ST-positive. These results indicate that dogs cause possible environmental problems as Salmonella carriers.

Animals↗
PubMed2002

An etiological investigation of domestic cats with conjunctivitis and upper respiratory tract disease in Japan.

Chlamydophila felis (C. felis), feline herpesvirus-1 (FHV-1) and feline calicivirus (FCV) were detected in 39 (59.1%), 11 (16.7%) and 14 (21.2%) cats respectively, from 66 domestic cats presented with conjunctivitis and upper respiratory tract disease (URTD) in 9 prefectures of Japan. Dual and multiple infections were found in 7 (10.6%) cats with both C. felis and FHV-1, 10 (15.2%) cats with both C. felis and FCV, and 1 (1.5%) cat with all three agents. C. felis was isolated from 11 (28.2%) of 39 PCR positive cats. Antigenic difference was found in a 96 kDa protein of our isolates and Fe/145 strain isolated in USA. In conclusion, C. felis is the most common agent of feline conjunctivitis and URTD, and the coinfection with C. felis, FHV-1 and FCV are also common in cats in Japan.

Animals↗