Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0023241 (Legionella)
 6,990 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We established a model of the bacteria-macrophage interaction to study the cellular basis of Legionella pneumophila pathogenesis and to characterize avirulent L. pneumophila. We found that U937 cells, which are derived from a human histiocytic lymphoma cell line, support intracellular growth of L. pneumophila with a doubling time of 6 h, and that sustained intracellular growth is associated with a cytopathic effect (CPE) that can be detected by microscopic examination and quantified with the vital stain 3-(4,5-dimethyl thiazol-2-yl)-2,5,-diphenyl tetrazolium bromide (MTT). An L. pneumophila isolate obtained directly from infected guinea-pig spleens can grow and produce CPE in these cells, destroying most of the cell layer after 72 h of growth. Only 10(6) organisms of this strain are required to kill 50% of guinea-pigs inoculated by the intraperitoneal route. In contrast, an avirulent isolate derived by 203 successive plate passages of the same strain can neither kill guinea-pigs at an intraperitoneal inoculum of 10(7) nor grow or produce CPE in U937 cells. Since the cells were able to differentiate between a virulent and an avirulent strain of L. pneumophila, we conclude that U937 cells are an appropriate model system for study of the bacteria-macrophage interaction.
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PMID:Growth of Legionella pneumophila in a human macrophage-like (U937) cell line. 323 54

A rapid colorimetric technique for in vitro quantitation of Legionella pneumophila intracellular proliferation in macrophages is described. The assay is based on the electron transport activity of metabolically active L. pneumophila. The yellow tetrazolium salt 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) is cleaved by the mitochondrial activity of viable L. pneumophila, forming a dark formazan derivative with an absorption spectrum different from that of the native compound. The MTT method for measuring intracellular growth of L. pneumophila closely correlated with the CFU assay. The ability of macrophages from the A/J mouse strain to support intracellular growth of L. pneumophila and the ability of desferrioxamine to restrict L. pneumophila intracellular proliferation were confirmed by both methods. The MTT assay offers the advantages of rapidity, simplicity, and cost efficiency over the CFU assay, since it can be performed in the same flat-bottom microtiter plate with measurement in an enzyme-linked immunosorbent assay reader, allowing efficient processing of large numbers of samples.
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PMID:A rapid colorimetric assay for evaluating Legionella pneumophila growth in macrophages in vitro. 812 66

We developed a new simple assay for the quantitation of the activities of drugs against intracellular Legionella pneumophila. The cells of a murine macrophage-like cell line (J774.1 cells) allowed the intracellular growth and replication of the bacteria, which ultimately resulted in cell death. The infected J774.1 cell monolayers in 96-well microplates were first treated with antibiotics and were further cultured for 72 h. The number of viable J774.1 cells in each well was quantified by a colorimetric assay with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and an enzyme-linked immunosorbent assay reader. The number of growing bacteria in each well was also determined by counting the numbers of CFU on buffered charcoal yeast extract-alpha agar plates. Viable J774.1 cell counts, determined by the colorimetric assay, were inversely proportional to the number of intracellular replicating bacteria. The minimum extracellular concentrations (MIECs) of 24 antibiotics causing inhibition of intracellular growth of L. pneumophila were determined by the colorimetric assay system. The MIECs of beta-lactams and aminoglycosides were markedly higher than the MICs in buffered yeast extract-alpha broth. The MIECs of macrolides, fluoroquinolones, rifampin, and minocycline were similar to the respective MICs. According to their intracellular activities, clarithromycin and sparfloxacin were the most potent among the macrolides or fluoroquinolones tested in this study. Our results indicated that the MTT assay system allows comparative and quantitative evaluations of the intracellular activities of antibiotics and efficient processing of a large number of samples.
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PMID:Simplified quantitative assay system for measuring activities of drugs against intracellular Legionella pneumophila. 957 12

We determined the MICs of ampicillin, ciprofloxacin, erythromycin, imipenem, and rifampin for two clinical isolates of Legionella pneumophila serogroup 1 by 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) reduction assay and by quantitative culture. To test the influence of subinhibitory concentrations (sub-MICs) of antimicrobial agents on Legionella uptake into Acanthamoeba castellanii and U937 macrophage-like cells, both strains were pretreated with 0.25 MICs of the antibiotics for 24 h. In comparison to that for the untreated control, subinhibitory concentrations of antibiotics significantly reduced Legionella uptake into the host cells. Measurement of the binding of monoclonal antibodies against several Legionella antigens by enzyme-linked immunoassays indicated that sub-MIC antibiotic treatment reduced the expression of the macrophage infectivity potentiator protein (Mip), the Hsp 60 protein, the outer membrane protein (OmpM), an as-yet-uncharacterized protein of 55 kDa, and a few lipopolysaccharide (LPS) epitopes. In contrast, the expression of some LPS epitopes recognized by monoclonal antibodies 8/5 and 30/4 as well as a 45-kDa protein, a 58-kDa protein, and the major outer membrane protein (OmpS) remained unaffected.
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PMID:Subinhibitory concentrations of antimicrobial agents reduce the uptake of Legionella pneumophila into Acanthamoeba castellanii and U937 cells by altering the expression of virulence-associated antigens. 979 18

Beta-dolabrin, gamma-thujaplicin, and 4-acetyltropolone, the components of Aomori Hiba (Thujopsis dolabrata SIEB. et ZUCC. var. hondai MAKINO), showed antifungal activity on seven kinds of plant-pathogenic fungi, antibacterial activity against two kinds of Legionella sp., and in vitro cytotoxic effect on murine P388 lymphocytic leukemia cell line. Firstly, beta-dolabrin, gamma-thujaplicin and 4-acetyltropolone had clear antifungal activity against seven kinds of plant-pathogenic fungi tested. In particular, beta-dolabrin and 4-acetyltropolone showed strong antifungal activity against Pythium aphanidermatum IFO 32440, with minimum inhibitory concentration (MIC) values of 6.0 microg/ml. Secondly, beta-dolabrin, gamma-thujaplicin and 4-acetyltropolone had obvious growth-inhibitory effect on two kinds of Legionella sp. 4-Acetyltropolone especially had strong antibacterial activity toward Legionella pneumophila SG 1, and its MIC value was 3.1 microg/ml. These three compounds showed cytotoxic effects against murine P388 lymphocytic leukemia cell line in vitro. The cytotoxic effect of three compounds in the murine P388 lymphocytic leukemia cell line were clear when cell growth was measured using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method. At 48 h after treatment, gamma-thujaplicin and 4-acetyltropolone at 0.63 microg/ml inhibited cell growth of murine P388 lymphocytic leukemia by 85% and 65%, respectively. At the same time after treatment, the growth of the murine P388 lymphocytic leukemia cell line was completely suppressed by the three compounds at concentrations higher than 5.0 microg/ml. Among these three compounds, gamma-thujaplicin had the strongest cytotoxic activity on the growth of this tumor cell line in vitro.
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PMID:Biological activity of beta-dolabrin, gamma-thujaplicin, and 4-acetyltropolone, hinokitiol-related compounds. 1546 16