MICROBIOLOGY and IMMUNOLOGY
Online ISSN : 1348-0421
Print ISSN : 0385-5600
ISSN-L : 0385-5600
Volume 43, Issue 4
Displaying 1-11 of 11 articles from this issue
  • Mandana Ashoori, Michio Ohta, Shinji Ohsuka, Keigo Shibayama, Toshinob ...
    1999 Volume 43 Issue 4 Pages 311-316
    Published: 1999
    Released on J-STAGE: March 17, 2008
    JOURNAL FREE ACCESS
    A series of new synthetic ligand compounds which chelate divalent cations was examined for the antibacterial activities of the compounds. Only 2 of 14 synthetic chelators, 9-trans-anthryl-1, 4, 8, 11-tetraazatetradecane (No. 6) and bis(2-pyridyl)methylamine (No. 13) showed antibacterial activities, whereas none of the diamines, hydrophilic triamines nor tetramines showed antibacterial activities. Chelators No. 6 and No. 13 inhibited the growth of both Gram-negative and -positive bacteria at doses of 25-200μg/ml, comparable to those of common antibiotics such as polymixin B, fosfomycin and macrolides. Ethylenediaminetetraacetate (EDTA) potentiated these antibacterial activities, whereas an inhibitory effect of Mg2+ on the MICs of these chelators was observed. Moreover, these chelators enhanced the leakage of periplasmic β-lactamase. It is therefore suggested that chelators No. 6 and No. 13 disrupt both the membranes and cytoplasmic functions of bacteria, resulting in cell death.
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  • Takashi Osada, Keiko Yamamura, Katsuhiro Fujimoto, Keisuke Mizuno, Tsu ...
    1999 Volume 43 Issue 4 Pages 317-321
    Published: 1999
    Released on J-STAGE: March 17, 2008
    JOURNAL FREE ACCESS
    An animal model was used to assess the efficacy of levofloxacin (LVFX) incorporated into albumin (ALB)-sealed Dacron (LVFX-ALB) graft for the prevention of vascular graft infections caused by Staphylococcus aureus. Under general anesthetic, an interposition graft was placed into dog carotid artery. On completion of the operation, 0.1ml of normal saline containing 107 colony-forming units (CFU) of a slime-producing S. aureus was inoculated directly onto the graft. After 1 day, the samples were sterilely harvested. The antibacterial activity of LVFX into the LVFX-ALB graft was evaluated by colony counting in bacterial cultures and by the fluorescent antibody method staining bacteria adhesion to the grafts. LVFX-ALB grafts had a lower infection rate than the control grafts (1/4, 102 CFU vs 4/4, 1.50×105±1.38×105 CFU (mean±SE)). In an immunostaining study, LVFX-ALB grafts had small fluorescent areas showing S. aureus adhesion, while fluorescence was observed over the entire surface of the control grafts. Therefore, LVFX-ALB presumably had a bactericidal action and adhesive prevention against inoculated S. aureus. LVFX-ALB may be useful in preventing graft infections during and immediately after vascular reconstruction.
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  • Norifumi Kudeken, Kazuyoshi Kawakami, Atsushi Saito
    1999 Volume 43 Issue 4 Pages 323-330
    Published: 1999
    Released on J-STAGE: March 17, 2008
    JOURNAL FREE ACCESS
    Penicillium marneffei is an important opportunistic fungal pathogen. The mechanisms of host defense against P. marneffei are not fully understood. In the present study, we, for the first time, investigated the role of superoxide anion (O2-) in the killing of two forms of P. marneffei, yeast cells and conidia, and the role of this killing mediator in the fungicidal activity of IFN-γ-stimulated murine peritoneal macrophages. P. marneffei yeast cells were susceptible to the killing effect of activated macrophages and chemically generated O2-, while conidia were not. These results suggested that O2- played some role in the fungicidal activity of macrophages. However, an oxygen radical scavenger, superoxide dismutase (SOD), did not suppress, but rather enhanced the fungicidal activity of IFN-γ-stimulated macrophages against P. marneffei yeast cells. This inconsistency was explained by the release of insufficient concentrations of O2- by activated macrophages as compared with the amount of O2- necessary for the killing of yeast cells, which was predicted in a chemical generating system. On the other hand, SOD enhanced the production of nitric oxide (NO) by IFN-γ-activated macrophages, and their increased fungicidal activity was significantly inhibited by NG-monomethyl-L-arginine (L-NMMA), a competitive inhibitor of NO synthase. Our results suggested that O2- does not function as the killing mediator of macrophages against P. marneffei, but rather plays an important role in the regulation of the NO-mediated killing system by suppressing NO production.
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  • Tae Takeda, Ken-ichi Yoshino, Eriko Adachi, Yuko Sato, Kyoko Yamagata
    1999 Volume 43 Issue 4 Pages 331-337
    Published: 1999
    Released on J-STAGE: March 17, 2008
    JOURNAL FREE ACCESS
    A synthetic analog of Shiga toxin (Stx) receptor (Synsorb Pk) was quantitatively assessed to determine whether it can protect human renal adenocarcinoma cells (ACHN cells) from the cytotoxicity of Stx1 and Stx2 by coincubation experiments. Coincubation of 100 and 20ng of Stx1 and Stx2 with 50mg of Synsorb Pk for 1hr at 37C in 1ml of Eagle's Minimum Essential Medium supplemented with 1% (v/v) nonessential amino acid and 10% (v/v) fetal calf serum protected 50% of the cells from the cytotoxic effect. Chromosorb P, an inert matrix control, did not absorb the Stxs at all. Heat-treatment (boiled for 10min) to Synsorb Pk caused a 50% decrease in Stx2-binding activity, but did not effect the Stx1 binding. Further, Stxs bound to Synsorb Pk could be demonstrated. When 20mg of Synsorb Pk was coincubated for 30min at 37C in 1ml of phosphate-buffered saline with 1 and 10ng or more of Stx1 or Stx2, respectively, the toxins could be detected on the surface when the bound toxins on Synsorb Pk were used as the solid phase in enzyme immunoassay. The amount of 100ng/ml of both Stx1 and Stx2 appeared to saturate 20mg/ml of Synsorb Pk after coincubating for 30min at 37C. While assessing the Stxs' binding activity to Synsorb Pk, it was demonstrated that Stx1 had a higher affinity to Pk trisaccharide than Stx2. These observations provide useful information on the effectiveness of Synsorb Pk to trap and eliminate free Stxs produced in the gut of patients infected by Stx-producing Escherichia coli, and to prevent the progression of hemorrhagic colitis to hemolytic uremic syndrome.
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  • Eiko Yabuuchi, Yoshimasa Kosako, Takashi Naka, Shinnichiro Suzuki, Iku ...
    1999 Volume 43 Issue 4 Pages 339-349
    Published: 1999
    Released on J-STAGE: March 17, 2008
    JOURNAL FREE ACCESS
    Based on the results of a phylogenetic analysis of 16S rRNA and the presence of sphingoglycolipid in cellular lipids of the type strains, transfer of “Rhizomonas” suberifaciens, Blastomonas natatoria and Erythromonas ursincola to the genus Sphingomonas as Sphingomonas suberifaciens (van Bruggen et al 1990) comb. nov., Sphingomonas natatoria (Sly 1985) comb. nov., and Sphingomonas ursincola (Yurkov et al 1997) comb. nov. are herein proposed together with the emendation of genus Sphingomonas. The type strain of S. suberifaciens is van Bruggen Ca1=ATCC 49382=NCPPB 3629=IFO 15211=JCM 8521, that of S. natatoria is ATCC 35951=DSM 3183=NCIMB 12085=JCM10396, and that of S. ursincola is DSM 9006=KR-99.
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  • Takatoshi Kawakami, Aki Kaneko, Nobuhiko Okada, Shinobu Imajoh-Ohmi, T ...
    1999 Volume 43 Issue 4 Pages 351-357
    Published: 1999
    Released on J-STAGE: March 17, 2008
    JOURNAL FREE ACCESS
    The slyA gene, which has been implicated in the virulence of Salmonella serovar Typhimurium and its survival in macrophages, is widely distributed among different Salmonella serovars. In this study, we cloned and sequenced the translational initiation region of the slyA gene from nine different serovars and found sequence differences in the previously proposed ATG initiation codon but not in a TTG triplet, another putative initiation codon in the slyA gene. Therefore, we determined the actual translational initiation site of the slyA gene by analyzing slyA genes with defined mutation in either the ATG or TTG sequences in an in vitro translation assay and a quantitative hemolytic assay in Escherichia coli. The replacement of TTG by TTC in the slyA gene significantly reduced both the amount of protein synthesized and the hemolytic activity of a transformed strain of E. coli, while replacement of ATG by ATC had no effect in these assays. In addition, the amino acid sequence analysis of the His-tagged SlyA protein showed that it was identical with the amino acid sequence deduced from the 5' end of the slyA gene with a TTG initiation codon. Our results suggest that TTG serves as the translational initiation codon for the slyA gene of Salmonella.
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  • Satoshi Kawasaki, Hitoshi Oshitani, Hiroshi Suzuki, Masaaki Arakawa, K ...
    1999 Volume 43 Issue 4 Pages 359-364
    Published: 1999
    Released on J-STAGE: March 17, 2008
    JOURNAL FREE ACCESS
    In order to investigate the longitudinal molecular epidemiology of cytomegalovirus (CMV) infections associated with bone marrow transplantation (BMT) in Japanese children, we analyzed 36 CMV strains from 11 cases. Three regions (DNA polymerase, glycoprotein H, and immediate-early regions) of CMV DNA were amplified by polymerase chain reaction (PCR), and amplified products were each digested with two restriction enzymes, followed by electrophoresis. These restriction fragment length polymorphism (RFLP) analyses allowed the differentiation of 36 strains into 13 genotypes. Each patient excreted his or her own CMV with distinct genotype over the study period of up to one year. CMVs of two different genotypes were recovered during a one-month study from one recipient, who received a peripheral blood stem cell transplantation. Although the majority of patients and donors were CMV-seropositive before BMT, multiple CMV infections might not be common and the reactivation of latently infected CMV might be prominent in Japanese children receiving transplants.
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  • Takeshi Yuasa, Takahiro Isono, Ikuo Tooyama, Akira Seto
    1999 Volume 43 Issue 4 Pages 365-371
    Published: 1999
    Released on J-STAGE: March 17, 2008
    JOURNAL FREE ACCESS
    Inbred rabbits of the B/Jas strain are highly susceptible to herpes simplex virus type-1 (HSV-1) encephalitis, developing seizures of encephalitis after intravenous injection of the KOS strain of the virus. Anti-viral interferon activity became detectable in the serum just prior to or at the onset of seizures, its level being lower in the serum than in the cerebrospinal fluid. The activity was of gamma interferon, as suggested by the acid instability and the inability of Mx protein induction. An immunohistochemical analysis of the brain tissues of encephalitic rabbits showed that MHC class I antigen was expressed on the microglia cells of inflamed lesions but not on these cells in uninflamed areas. These findings were discussed in correlation with the pathogenesis of herpetic encephalitis in the inbred rabbits.
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  • Ryo Harasawa, Massimo Giangaspero
    1999 Volume 43 Issue 4 Pages 373-379
    Published: 1999
    Released on J-STAGE: March 17, 2008
    JOURNAL FREE ACCESS
    Sixteen clinical strains of classical swine fever virus (CSFV) isolated in Japan were subjected to analyses of nucleotide sequence variations in the 5' end and NS5B regions of the genome. These isolates were divided into three genovars, CSFV-1, CSFV-2 and CSFV-3, based on palindromic nucleotide substitutions at the three variable loci in the 5' untranslated region (UTR). Phylogenetic trees constructed from nucleotide sequences in the 5'-UTR and NS5B gene indicated that the CSFV strains were divided into three clusters, I, II and III. CSFV strains included in clusters I, II and III were identical to those in the CSFV-1, CSFV-2 and CSFV-3 genovars, respectively.
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  • Sou-ichi Makino, Hiroshi Asakura, Toshikazu Shirahata, Tetsuya Ikeda, ...
    1999 Volume 43 Issue 4 Pages 381-384
    Published: 1999
    Released on J-STAGE: March 17, 2008
    JOURNAL FREE ACCESS
    We made a molecular analysis of O157:H45 Escherichia coli isolated from a mass outbreak that occurred in Obihiro City. Using DNA analysis, we confirmed this infection case as a mass outbreak. Although the isolates expressed O157 antigen, they did not produce Vero toxin. We concluded they were enteropathogenic E. coli (EPEC) because they had a bfp gene and an EAF plasmid, and further they exhibited local adherence to HEp-2 cells. We believe this is the first report of a mass outbreak by O157 EPEC, and we suggest that PCR using eae- and bfp-specific primers and HEp-2 adherence assay are useful to identify EPEC.
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  • Noboru Nakasone, Masahide Ikema, Naomi Higa, Tetsu Yamashiro, Masaaki ...
    1999 Volume 43 Issue 4 Pages 385-388
    Published: 1999
    Released on J-STAGE: March 17, 2008
    JOURNAL FREE ACCESS
    A filamentous phage, ‘Ivpf5, ’ of Vibrio parahaemolyticus O3:K6 strain LVP5 was isolated and characterized. The host range was not restricted to serotype O3:K6, but 7 of 99 V. parahaemolyticus strains with a variety of serotypes were susceptible to the phage. The phage was inactivated by heating at 80C for 10min and by treating with chloroform. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the phage exhibited a 3.8kDa protein. The amino-terminal amino acid sequence of the coat protein was determined as AEGGAADPFEAIDLLGVATL. The phage genome consisted of a single-stranded DNA molecule. The activity of the phages was inhibited by anti-Na2 pili antibody.
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