Biomedical subjects
Yutaka Tamura
Publications and source records attributed to Yutaka Tamura.
Detection of ehrlichial DNA in small rodents captured in a woodland area of Hokkaido, the northernmost island of Japan, where Lyme disease is endemic.
The ehrlichial gene was detected in small rodents trapped in a Lyme disease-endemic area in Hokkaido, the northernmost island of Japan. Primer pairs of 16S rDNA targeting the genus Ehrlichia and other regions of the 16S rDNA specific for E. chaffeensis and E. muris were used for identification. The DNA fragment specific for 16S rDNA of Ehrlichia spp. was detected in 4 of 94 Apodemus speciosus mice (positive rate: 4.3%) and 5 of 73 Clethrionomys rufocanus bedfordiae mice (positive rate: 6.8%). The nucleotide sequence of the amplified 16S rDNA fragment was most similar to those of E. muris-like Ehrlichia, Ehrlichia spp. HF565 and Shizuoka-36, originating in the northern and central parts of Japan. In phylogenetic analysis based on 16S rDNA sequences, the northern, central and western groups of E. muris-like Ehrlichia from a cluster with microorganisms of the E. muris group. These results suggest that there are a group of E. muris microorganisms and a group of E. muris- like microorganisms in Japan.
Correlation between the usage volume of veterinary therapeutic antimicrobials and resistance in Escherichia coli isolated from the feces of food-producing animals in Japan.
We compared the overall usage of veterinary therapeutic antimicrobials in Japan to the proportion of antimicrobial-resistant. Escherichia coli isolated from the feces of apparently healthy food-producing animals in 2001. The annual sales volume of veterinary antimicrobials, which is published and accumulated information, was subdivided according to the target animal species (cattle, pigs, broiler chickens, and layer chickens). The antimicrobial susceptibility of the isolates was examined against 7 classes of 11 antimicrobials. The rates of antimicrobial resistance among the isolates were found to correlate significantly with the usage of antimicrobial agents in cattle, pigs, and broiler and layer chickens. Therefore, the overall usage of veterinary antimicrobials appears to contribute to the appearance of antimicrobial resistance in E. coli isolates from apparently healthy food-producing animals.
Oligodeoxynucleotides having a loop consisting of 3'-deoxy-4'-C-(2-hydroxyethyl)thymidines form stable hairpins.
Components that form stable hairpin loops are highly useful for the development of functional DNA and RNA molecules. We have designed and synthesized a sugar-modified thymidine analogue, 3'-deoxy-4'-C-(2-hydroxyethyl)thymidine (X), as a nucleosidic loop component stabilizing the hairpin structure. The ODNs I-1-4, 5'-d[CGAACG-X(n)-CGTTCG]-3' (I-1, n = 1; I-2, n = 2; I-3, n = 3; I-4, n = 4), forming the hairpin loop structures, of which the loop moiety consisted of the analogue X, and also the corresponding unmodified ODNs II-1-4, 5'-d[CGAACG-T(n)-CGTTCG]-3' (II-1, n = 1; II-2, n = 2;II-3, n = 3; II-4, n = 4), having a thymidine loop, were synthesized by the phosphoramidite method. The melting temperatures (T(m)) of the ODNs I-1-4 containing X in the loop moiety at 5 microM were 67.1, 68.1, 73.0, and 69.3 degrees C, respectively, and those of the control natural ODNs II-1-4 were 65.3, 67.0, 69.2, and 68.8 degrees C, respectively. Thus, the ODNs I-1-4 formed a more thermally stable hairpin than the corresponding unmodified ODNs II-1-4 having an equal number of loop residues. The hairpin structures of the modified ODNs I-1-4 and the unmodified ODNs II-1-4 were investigated by CD spectroscopy and molecular mechanics calculations. These results showed that the 4'-branched nucleoside X can stabilize hairpin structures when it is present in the loop moiety, probably due to the flexibility of the one-carbon-elongated 4'-branched structure.
Antimicrobial susceptibility of Salmonella isolated from cattle, swine and poultry (2001-2002): report from the Japanese Veterinary Antimicrobial Resistance Monitoring Program.
OBJECTIVES: The Japanese Veterinary Antimicrobial Resistance Monitoring (JVARM) Program was established in 1999 to examine the susceptibility of bacteria from food-producing animals to antimicrobial agents. This study tested the susceptibility of Salmonella isolates collected during 2001-2002 to 20 antimicrobials. MATERIALS AND METHODS: MICs of antimicrobial agents were determined using the NCCLS agar dilution method, and interpreted according to breakpoints obtained from the bimodal MIC distributions. RESULTS: A total of 82 Salmonella were isolated from food-producing animals and tested for antimicrobial susceptibility. Isolates resistant to ampicillin, dihydrostreptomycin, kanamycin, oxytetracycline, chloramphenicol, bicozamycin, nalidixic acid, oxolinic acid and trimethoprim were obtained from healthy animals and diagnostic sample submissions. Salmonella Dublin was isolated only from cattle and showed resistance to older quinolones. Resistance to ampicillin, dihydrostreptomycin, kanamycin and oxytetracycline was common across all serotypes. Fluoroquinolone-resistant Salmonella Choleraesuis was isolated from swine and was the first Japanese report on this type of resistance in Salmonella from an animal origin. Most Salmonella Typhimurium isolates showed resistance to ampicillin, chloramphenicol, dihydrostreptomycin and oxytetracycline. S. Typhimurium DT104 accounted for 40.7% of S. Typhimurium isolates and was more often multi-drug resistant. Most Salmonella Infantis isolates from poultry showed resistance to dihydrostreptomycin, oxytetracycline, trimethoprim or kanamycin. In Salmonella Enteritidis, the major serotype isolated from food-poisoning in Japan, only resistance to dihydrostreptomycin was observed. CONCLUSIONS: This is the first JVARM report of Salmonella isolates, and continuous investigations at the national level on antimicrobial resistance in Salmonella isolated from food-producing animals will be important in the JVARM Program.
Evaluation of the bacterial endotoxin test for quantification of endotoxin contamination of porcine vaccines.
We investigated the application of the bacterial endotoxin test for the quantification of the endotoxin contamination of various commercial porcine vaccines. In endotoxin-spiked samples, Freund's complete adjuvant and aluminum hydroxide gel adjuvant failed to interfere with the results of the endotoxin test, and both recovery ratios were within the permissible range mentioned in the Japanese Pharmacopoeia. At the various dilutions tested, none of the adjuvants in commercial porcine vaccines caused noteworthy interference in the test. In addition, none of the 39 samples of porcine vaccines approved in Japan induced an interfering effect in the endotoxin test. Our findings suggest that the bacterial endotoxin test using endotoxin-specific Limulus amoebocyte lysate (LAL) can detect endotoxin contamination in commercial porcine vaccines containing either oil or aluminum adjuvants.
Antimicrobial susceptibilities of Campylobacter isolated from food-producing animals on farms (1999-2001): results from the Japanese Veterinary Antimicrobial Resistance Monitoring Program.
Nationwide monitoring of antimicrobial resistance in Campylobacter isolated from food-producing animals on farms was performed in Japan. A total of 468 Campylobacter isolates were obtained during the period from June 1999 to March 2001. Campylobacter species showed high frequencies of resistance to oxytetracycline and dihydrostreptomycin. The frequencies of resistance in Campylobacter coli to aminoglycosides, macrolides, tetracycline and quinolones were higher than those in Campylobacter jejuni to the same drugs. All of the C. jejuni isolates were susceptible to macrolide antibiotics, whereas 48.4% of the C. coli isolates were resistant to macrolides. Resistance to fluoroquinolones was observed in C. jejuni isolates from broilers (12%) and layers (2.6%), indicating that the level of fluoroquinolone resistance in Japan could be ranked as low.
Rapid detection of quinolone-resistant Salmonella by real time SNP genotyping.
A total of 63 isolates were screened for the gyrA mutation (87Asp-Tyr) in Salmonella enterica serovars using real time PCR. All of the isolates were successfully identified as resistant or susceptible, consistent with the MIC result of the agar dilution method and gyrA sequencing.
Stable hairpins having a loop consisting of 3'-deoxy-4'-C-(2-hydroxyethyl)thymidines.
A novel sugar-modified thymidine analogue, 3'-deoxy-4'-C-(2-hydroxyethyl)thymidine (X), was designed and synthesized to show that it can stabilize hairpin structures when it is present in the loop moiety, probably due to the flexibility of the one-carbon-elongated 4'-branched structure.
Epidemiological characterization of Salmonella Typhimurium DT104 prevalent among food-producing animals in the Japanese veterinary antimicrobial resistance monitoring program (1999-2001).
In the course of nationwide investigation on epidemiological characteristics in Salmonella Typhimurium isolates from food-producing animals in Japan between 1999 and 2001, fifty-seven isolates of S. Typhimurium DT104 and 104B obtained from cattle and swine at farm level in Japan between 1999 and 2001 were classified with pulsotype and antimicrobial resistance type. Most of the isolates were resistant to five or more antimicrobials and were genotyped into four groups. The present nationwide investigation shows that at least 11 types of S. Typhimurium related to DT104 are prevalent among food-producing animals across the country.
Effect of lipopolysaccharide (LPS) injection on the immune responses of LPS-sensitive mice.
The effect of lipopolysaccharide (LPS) on humoral and cell-mediated immunity was assessed using LPS-sensitive C3H/HeN mice. A single injection of LPS significantly decreased the anti-sheep red blood cells (SRBC) antibody titers, but not the number of anti-SRBC antibody producing spleen cells. In contrast, double LPS injection did not significantly decrease the anti-SRBC titers and even increased the number of anti-SRBC antibody producing spleen cells. Similarly, single LPS injection significantly suppressed the swelling of the footpad, but double LPS injection caused milder suppression. These results suggest that a difference in the level and timing of exposure to LPS may influence the immune response to infection or vaccination.
Comparison of fluoroquinolone resistance genes of Salmonella enterica serovar Choleraesuis isolates in Japan and Taiwan.
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A national surveillance of antimicrobial resistance in Escherichia coli isolated from food-producing animals in Japan.
A nationwide investigation of antimicrobial susceptibility in Escherichia coli isolated from food-producing animals was performed in Japan. MICs of 18 antimicrobial agents were determined for a total of 1018 isolates. Higher resistance rates were observed against sulfadimethoxine, oxytetracycline and dihydrostreptomycin, followed by ampicillin and kanamycin. Resistance was more frequently observed among broiler isolates, followed by isolates from pigs. Almost 10% of broiler isolates were resistant to fluoroquinolones and extremely high MICs (100 mg/L) were observed. In general, antimicrobial resistance rates in E. coli have declined in recent years, with the exception of resistance to fluoroquinolones among broiler isolates, which has increased.
Standards of the in vitro mutation frequency study and the antimicrobial activity study in gut.
In view of the recent rapid increase in incidence of infection with antimicrobial resistant bacteria in human medicine, there is international controversy as to the medical risk that is created by transfer of antimicrobial resistant bacteria and antimicrobial resistant genes, which may be produced through the processes of administration of antimicrobials to food-producing animals, via the food chain. Accordingly, International Cooperation on Harmonization of Technical Requirements for Registration of Veterinary Medicinal Products (VICH) provides the comprehensive guidelines for characterizing selection of antimicrobial resistance by bacteria which may adversely affect human health in order to establish the system of registry of antimicrobial drugs to be administered to food- producing animals. Currently, Japanese Society of Antimicrobials for Animals recognizes the lack of technical test standards in compliance with VICH guidelines in the world and has established the test standards for "in vitro mutation frequency studies" to evaluate the appearance frequency and resistant level of resistant bacteria and those for studies on the "antimicrobial activity in gut" to estimate the effects on intestinal flora from professional aspects.
[Resource utilization of gastric cancer patients aggregated item-by-item and comparison of the medical costs with the reimbursement level and length of hospital stay].
OBJECTIVE: Using the new hospital cost accounting method per case based on cost per service, we compared the medical costs with the reimbursement level and length of hospital stay for gastric cancer patients. METHOD: The subjects were 158 gastric cancer patients who were admitted for surgery in a public hospital in Tokyo between 1995 and 1997. The new cost accounting method that we developed according to the activity-based costing method was applied in the following four levels; major items of expenditure for the hospital; costs incurred in each department; costs per medical service units; and costs of all the services per case. RESULTS: 1) 158 patients were studied. All the cost figures are adjusted to those in the 1998 fiscal year. The mean length of stay (LOS) of the 158 cases were 52 +/- 16 days. The average charge was 1,835,000 yen, and the average costs was 2,034,000 yen. 2) The per capita ratio of charge to cost (RCC) was 0.90. RCC for medications, procedure treatments, laboratory tests, and medical management/accommodation were 1.04, 1.44, 1.35, and 0.31, respectively. 3) The peason's correlation coefficient between the total costs and LOS was 0.80 (P < 0.001). A high correlation was noted for costs for medical management/accommodation and nursing with LOS (r = 0.98, P < 0.001; r = 0.97, P < 0.001; respectively), while that for cost for operations was low (r = 0.03, P > 0.05). The partial correlation coefficient between the total costs and the total charges with the LOS adjustment was 0.58 (P < 0.001). The coefficient for costs and charges for medications and procedure were high (r = 0.99, P < 0.001; r = 1.00, P < 0.001), while that for medical management/accommodation was low (r = 0.16, P < 0.001). CONCLUSIONS: LOS reflected the cost for room and nursing, but not the resource consumption for medical treatment per case. While the present fee schedules overestimate the costs of medication and laboratory tests, they underestimate those for medical management/accommodation. LOS and charges did not correctly reflect the medical costs per case.
Phylogenetic analysis and PCR detection of Clostridium chauvoei, Clostridium haemolyticum, Clostridium novyi types A and B, and Clostridium septicum based on the flagellin gene.
The flagellin genes (fliC) of Clostridium chauvoei, Clostridium haemolyticum, Clostridium novyi types A and B, and Clostridium septicum were analysed by PCR amplification and DNA sequencing. The five Clostridium species have at least two copies of the flagellin gene (fliC) arranged in tandem on the chromosome. The deduced N- and C-terminal aminoacid sequences of the flagellin proteins (FliCs) of these clostridia are well conserved but their central region aminoacid sequences are not. Phylogenic analysis based on the N-terminal aminoacid sequence of the FliC protein revealed that these clostridia, which belong to Clostridium 16S rDNA phylogenic cluster I (), are more closely related to Bacillus subtilis than to Clostridium difficile, which belongs to the cluster XI. Moreover, a multiplex polymerase reaction (PCR) system based on the fliC sequence was developed to rapidly identify C. chauvoei, C. haemolyticum, C. novyi types A and B, and C. septicum. PCR of each Clostridium amplified a species-specific band. The multiplex PCR system may be useful for rapid identification of pathogenic clostridia.
Surface properties and biocompatibility of nitrided titanium for abrasion resistant implant materials.
Corrosion, other related properties and biocompatibility of surface nitrided titanium were investigated to examine its possible use as an abrasion resistant implant material. The nitrided layer about 2 microm thick composed of TiN and Ti2N was formed on titanium by a gas nitriding method. The dissolved amount of titanium ion in SBF was as low as the detection limit of ICP, and that in the 1% lactic acid showed no significant difference from titanium. The tissue reaction of the cylindrical implant in soft tissue of rats showed no inflammation, and fine particles of 1 microm induced phagocytosis, which was similar to titanium. The implantation in the femor showed the new bone formed in direct contact with implants. All the results suggested that the wettability, corrosion resistance, S. mutans adhesion and biocompatibility were nearly equivalent to those of titanium. The surface of nitrided titanium was promising, with biocompatibility comparable with titanium, as an implant material such as for an abutment part of a dental implant, which requires high abrasion resistance.