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  • 1
    ISSN: 1520-510X
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1523-5378
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background. Clarithromycin-resistant Helicobacter pylori (CRHP) is increasing worldwide. Clarithromycin resistance in H. pylori from familial members has not been investigated.Materials and Methods. Biopsy specimens were taken from 13 families living in Tokyo, Yokohama, and Niigata between 1998 and 2001. Drug resistance was tested with the replica plating method. The minimum inhibitory concentrations of antimicrobial agents for H. pylori strains were determined by the agar dilution method. Molecular analyses of H. pylori strains were performed by ribosomal RNA gene restriction pattern analysis. The DNA region, associated with clarithromycin resistance, was analyzed by PCR and sequencing.Results. Helicobacter pylori strains isolated from a 5-year-old-son displayed clarithromycin resistance with a mutation (A → G at position 2143) in the 23S ribosomal RNA, whereas H. pylori strains from his parents did not. DNA analyses revealed that the boy was infected with his father's strain. The boy had repeatedly developed otitis media and received clarithromycin since the age of 2 years. Studies on an additional 12 families demonstrated that clarithromycin resistance in the children's strains reached 42.9% and was significantly higher than those of H. pylori strains from their parents (0%) or from adult patients (11.1%) (p 〈 .05).Conclusions. The rate of clarithromycin resistance in H. pylori strains from Japanese children was extremely high, in contrast to those from their parents or adult patients. Prior history of clarithromycin usage in a child suggested development of clarithromycin resistance in resident H. pylori, which was originated from a parent.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1523-5378
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes:  Clarithromycin-resistant Helicobacter pylori (CRHP) has increasingly been isolated from patients in Japan. The aim of our study was to test whether proton pump inhibitors (PPIs) and their thioether derivatives, which are secreted into the gastric mucosa, could inhibit the growth and motility (a factor in colonization) of CRHP.〈section xml:id="abs1-3"〉〈title type="main"〉Materials and Methods. CRHP was isolated from patients who had experienced gastritis or peptic ulcers in Tokyo and Niigata. Drugs and related agents tested were omeprazole, lansoprazole, rabeprazole, the thioether derivative of rabeprazole (rabeprazole-TH), clarithromycin, amoxicillin and metronidazole. The MICs of the drugs and agents for H. pylori strains were determined by the agar dilution method. Bacterial swimming in a liquid layer was examined under an inverted, phase-contrast microscope.〈section xml:id="abs1-4"〉〈title type="main"〉Results. The PPIs and rabeprazole-TH, but not the anti-H. pylori agents, inhibited the motility of CRHP at both pH 7.4 and 6.0. The concentrations (µg/ml) necessary to inhibit 50% of the motility at pH 7.4 were 0.25–0.5, 8–32, 8–16 and 128–256 for rabeprazole-TH, rabeprazole, lansoprazole and omeprazole, respectively. Rabeprazole-TH exibited the strongest inhibitory effect against the growth of CRPH (MIC, 0.5 µg/ml).〈section xml:id="abs1-5"〉〈title type="main"〉Conclusion. Rabeprazole-TH, which is secreted into the gastric mucosa, had the strongest inhibitory action against both the growth and motility of CRHP, suggesting that it is a potential novel agent for CRHP eradication.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Journal of periodontal research 37 (2002), S. 0 
    ISSN: 1600-0765
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The cytocidal effect of seven macrolide antibiotics on human periodontal ligament fibroblasts (Pel cells) was studied. Pel cells were exposed for 48 h to erythromycin (EM), clarithromycin (CAM), roxithromycin (RXM), azithromycin (AZM), josamycin (JM), midecamycin (MDM), and rokitamycin (RKM), and allowed to form colonies. The cytocidal effect of the macrolides was measured as a decrease in colony-forming efficiency and was found to increase with the concentration. To obtain a quantitative measure of the cytocidal effect, the LD50, i.e. the concentration that decreases colony-forming efficiency 50% relative to control cells, was extrapolated from the concentration-response curves. The rank of the macrolides according to their cytocidal effect (LD50) was RKM 〉 RXM 〉 CAM 〉 AZM 〉 JM 〉 MDM ≈ EM. RKM, RXM, CAM, AZM, and JM were at least 1.7–12.2 times more cytocidal than MDM or EM. When extrapolated from the concentration-response curves, the relative survival of the Pel cells exposed to each of the macrolides at the MIC90 concentrations for periodontopathic bacteria was estimated to be: ≥ 53.8% for RKM, ≥ 92.7% for RXM, ≥ 94.6% for CAM, ≥ 97.1% for AZM, and ≥ 86.2% for EM. The effect of the antibiotics on the mRNA expression of alkaline phosphatase (ALP) and type I procollagen (COL) was examined in Pel cells exposed for 48 h to RXM, CAM, AZM, and EM, which exhibited strong, moderate, and weak cytocidal activity. The constitutive levels of both ALP and COL mRNA were retained in cells exposed to RXM at ≤3 μM, CAM at ≤10 μM, and AZM or EM at ≤3 μM. The MIC90 against periodontopathic bacteria is ≤4.8 μM for RXM, 5.3 μM for CAM, 2.7 μM for AZM, and 21.8 μM for EM. These results suggest that topical administration of CAM or AZM to the gingival crevice at their MIC90 concentration for periodontopathic bacteria would have little adverse effect on the growth and differentiation of the periodontal ligament. It is important to note, however, that these findings have yet to be extrapolated to in vivo conditions.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Copenhagen : Munksgaard International Publishers
    Journal of periodontal research 35 (2000), S. 0 
    ISSN: 1600-0765
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The fluoroquinolone ofloxacin (OFLX) is one of the candidates of antibacterial agents to be topically used against periodontitis. To estimate the maximum concentration of OFLX which exerts little or no adverse effect on the periodontal ligament, cytological and cytogenetic effects of OFLX on human periodontal ligament fibroblasts (Pel cells) were examined. Treatment of Pel cells with ≤0.3 mm OFLX for 24 or 48 h had little inhibitory effect on cellular growth and survival. DNA, RNA and protein syntheses in Pel cells did not decrease in response to treatment with ≤0.3 mm OFLX. The constitutive level of alkaline phosphatase mRNA was retained in cells treated with ≤0.03 mm OFLX for 24 or 48 h. The level of type I procollagen mRNA was not affected by treatment with ≤0.003 mm OFLX for 24 or 48 h. Cytogenetic effects of OFLX were evaluated by the ability of OFLX to induce chromosome aberrations in Pel cells. Treatment with OFLX at 0.3–3.0 mm for 6, 24, or 48 h failed to induce chromosome aberrations in Pel cells. The failure of OFLX to induce chromosome aberrations was seen even in the presence of exogenous metabolic activation using a 5% rat liver post-mitochondrial supernatant mixture. These results indicate that treatment of Pel cells with ≤0.003 mm OFLX has few or no adverse effects on the cytological and cytogenetic endpoints examined, suggesting that there would be little adverse effect on growth and differentiation of the periodontal ligament, as well as little cytogenetic activity, if OFLX were to be topically administered to the gingival crevice at the minimal inhibitory concentration (MIC90) against periodontopathic bacteria (≤0.0027 mm). It is important to note, however, that extrapolation of these findings to in vivo conditions has yet to be undertaken.
    Type of Medium: Electronic Resource
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