Acetylation of fluoroquinolone antimicrobial agents by an Escherichia coli strain isolated from a municipal wastewater treatment plant.

AIMS: To isolate environmental bacteria capable of transforming fluoroquinolones to inactive molecules. METHODS AND RESULTS: Bacteria were isolated from the aerobic liquor of a wastewater treatment plant on a medium containing norfloxacin (100 mg l(-1)). Twenty-two isolates were highly resistant (minimal inhibitory concentration: 6.25-200 microg ml(-1)) to five fluoroquinolones and six of them were positive by PCR amplification for the aminoglycoside resistance gene aac(6')-Ib. Of these, only Escherichia coli strain LR09 had the ciprofloxacin-acetylating variant gene aac(6')-Ib-cr; HPLC and mass spectrometry showed that this strain transformed both ciprofloxacin and norfloxacin by N-acetylation. This bacterium also had mutations in the quinolone-resistance determining regions of the gyrA and parC genes. CONCLUSIONS: An E. coli isolate from wastewater, which possessed at least two distinct fluoroquinolone resistance mechanisms, inactivated ciprofloxacin and norfloxacin by N-acetylation. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first report of N-acetylation of fluoroquinolones by an aac(6')-Ib-cr-containing bacterium from an environmental source.

Two new monoterpene peroxide glycosides from Aster scaber.

The aerial part of Aster scaber Thunb. (Asteraceae) yielded two new monoterpene peroxide glycosides, (3S)-3-O-(3',4'-diangeloyl-beta-D-glucopyranosyloxy)-7-hydroperoxy-3,7-dimethylocta-1,5-diene (1) and (3S)-3-O-(3',4'-diangeloyl-beta-D-glucopyranosyloxy)-6-hydroperoxy-3,7-dimethylocta-1,7-diene (2), and five known compounds, alpha-spinasterol (3), germacra-4(15),5,10(14)-triene-1-beta-ol (4), 7-methoxy-4(15)-oppositen-1-beta-ol (5), 6alpha-methoxy-4(15)-eudesmane-1beta-ol (6) and alpha-spinasterol 3-O-beta-D-glucopyranoside (7). The structures were established by chemical and spectroscopic methods.

A new caffeoyl quinic acid from aster scaber and its inhibitory activity against human immunodeficiency virus-1 (HIV-1) integrase.

The phytochemical study of the aerial parts of Aster scaber Thunb. (Asteraceae) yielded a new caffeoyl quinic acid, (-) 3,5-dicaffeoyl-muco-quinic acid (2) and three known compounds, (-) 3,5-dicaffeoyl quinic acid (1), (-) 4,5-dicaffeoyl quinic acid (3), (-) 5-caffeoyl quinic acid (4). The structures were established by high resolution spectroscopic methods. The antiviral effects against HIV-1 integrase of the compounds was evaluated. (-) 3,5-Dicaffeoyl-muco-quinic acid (2) exhibited potent antiviral activity with an IC50 value of 7.0 +/- 1.3 microg/ml.

Inducible nitric oxide synthase inhibitors from Melia azedarach var. japonica.

In bioassay-guided search for inducible nitric oxide synthase (iNOS) inhibitory compounds from higher plants of South Korea, two beta-carboline alkaloids, 4-methoxy-1-vinyl-beta-carboline (1) and 4,8-dimethoxy-l-vinyl-beta-carboline (2) have been isolated from the cortex of Melia azedarach var. japonica. The structures of these compounds were elucidated on the basis of spectroscopic data. Compounds 1 and 2 showed marked inhibitory activity of iNOS on LPS- and interferon-gamma-stimulated RAW 264.7 cells.

A reduction in allergen-induced Fc epsilon R2/CD23 expression on peripheral B cells correlates with successful hyposensitization in grass pollinosis.

BACKGROUND: The cellular basis for the mechanism of specific hyposensitization is still unclear. OBJECTIVE: We prospectively studied the effect of immunotherapy on allergen-induced proliferation and Fc epsilon R2/CD23 expression of lymphocytes. METHODS: Mononuclear cells prepared from the peripheral blood of 22 patients with grass pollen (GP) allergy before, during, and after a preseasonal immunotherapy period with GP were stimulated with GP or control antigens. Tritiated thymidine uptake and percentage of CD23+ B cells were determined daily during days 6 to 8 and compared with lymphocyte responsiveness of 11 only symptomatically treated atopic patients and 14 nonatopic individuals. RESULTS: GP-induced lymphocyte proliferative response of both hyposensitized and symptomatically treated GP-allergic patients decreased markedly before the pollen season and rose again after seasonal allergen exposure, whereas a long-lived decrease in GP-induced Fc epsilon R2/CD23+ B cells was only observed in GP-treated patients. Alterations in Fc epsilon R2/CD23 expression were closely related to changes in symptoms and medication requirement during the following pollen season. In contrast, immunotherapy had no effect on Fc epsilon R2/CD23 expression of B cells without stimulation or on B cells cultured in the presence of control antigens. CONCLUSION: Because Fc epsilon R2/CD23 expression on B cells is antagonistically regulated by the cytokines interleukin-4 and interferon-gamma, the decrease of allergen-induced Fc epsilon R2/CD23+ B cells indicates an altered cytokine secretion pattern of the allergen-specific T lymphocytes with a predominance of interferon-gamma.