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91.
A simple and convenient microtiter plate assay for the detection of bactericidal antibodies to Vibrio cholerae O1 and Vibrio cholerae O139 总被引:1,自引:0,他引:1
Boutonnier A Dassy B Duménil R Guénolé A Ratsitorahina M Migliani R Fournier JM 《Journal of microbiological methods》2003,55(3):745-753
It is believed that the correlate of protection for cholera can be determined by the serum vibriocidal assay. The currently available vibriocidal assays, based on the conventional agar plating technique, are labor intensive. We developed a simple and convenient microtiter plate assay for the detection of vibriocidal antibodies that is equally as efficient for Vibrio cholerae O1 and for V. cholerae O139. The addition of succinate and neotetrazolium made it possible to measure the growth of surviving bacterial target cells by monitoring a color change. We evaluated assay parameters (target strains, growth of target cells, complement source and concentration) that may affect the reproducibility of the method for V. cholerae O139. The results obtained with the microtiter plate assay were uniformly similar to those obtained with the conventional agar plating assay, when testing both the Inaba and Ogawa serotypes of V. cholerae O1. The microtiter plate assay was also convenient for measuring the activity of animal sera and mouse monoclonal antibodies. 相似文献
92.
Structure and axon outgrowth inhibitor binding of the Nogo-66 receptor and related proteins 总被引:23,自引:0,他引:23
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Barton WA Liu BP Tzvetkova D Jeffrey PD Fournier AE Sah D Cate R Strittmatter SM Nikolov DB 《The EMBO journal》2003,22(13):3291-3302
The myelin-derived proteins Nogo, MAG and OMgp limit axonal regeneration after injury of the spinal cord and brain. These cell-surface proteins signal through multi-subunit neuronal receptors that contain a common ligand-binding glycosylphosphatidylinositol-anchored subunit termed the Nogo-66 receptor (NgR). By deletion analysis, we show that the binding of soluble fragments of Nogo, MAG and NgR to cell-surface NgR requires the entire leucine-rich repeat (LRR) region of NgR, but not other portions of the protein. Despite sharing extensive sequence similarity with NgR, two related proteins, NgR2 and NgR3, which we have identified, do not bind Nogo, MAG, OMgp or NgR. To investigate NgR specificity and multi-ligand binding, we determined the crystal structure of the biologically active ligand-binding soluble ectodomain of NgR. The molecule is banana shaped with elongation and curvature arising from eight LRRs flanked by an N-terminal cap and a small C-terminal subdomain. The NgR structure analysis, as well as a comparison of NgR surface residues not conserved in NgR2 and NgR3, identifies potential protein interaction sites important in the assembly of a functional signaling complex. 相似文献
93.
94.
Bachmann TT Leca B Vilatte F Marty JL Fournier D Schmid RD 《Biosensors & bioelectronics》2000,15(3-4):193-201
Engineered variants of Drosophila melanogaster acetylcholinesterase (AChE) were used as biological receptors of AChE-multisensors for the simultaneous detection and discrimination of binary mixtures of cholinesterase-inhibiting insecticides. The system was based on a combination of amperometric multielectrode biosensors with chemometric data analysis of sensor outputs using artificial neural networks (ANN). The multisensors were fully manufactured by screen-printing, including enzyme immobilisation. Two types of multisensors were produced that consisted of four AChE variants each. The AChE mutants were selected in order to obtain high resolution, enhanced sensitivity and minimal assay time. This task was successfully achieved using multisensor I equipped with wild-type Drosophila AChE and mutants Y408F, F368L, and F368H. Each of the AChE variants was selected on the basis of displaying an individual sensitivity pattern towards the target analytes. For multisensor II, the inclusion of F368W, which had an extremely diminished paraoxon sensitivity, increased the sensor's capacity even further. Multisensors I and II were both used for inhibition analysis of binary paraoxon and carbofuran mixtures in a concentration range 0-5 microg/l, followed by data analysis using feed-forward ANN. The two analytes were determined with prediction errors of 0.4 microg/l for paraoxon and 0.5 microg/l for carbofuran. A complete biosensor assay and subsequent ANN evaluation was completed within 40 min. In addition, multisensor II was also investigated for analyte discrimination in real water samples. Finally, the properties of the multisensors were confirmed by simultaneous detection of binary organophosphate mixtures. Malaoxon and paraoxon in composite solutions of 0-5 microg/l were discriminated with predication errors of 0.9 and 1.6 microg/l, respectively. 相似文献
95.
Acetylcholinesterase is the primary target of organophosphorous and carbamate insecticides. Quantitative changes in acetylcholinesterase are suspected to confer resistance to these insecticides, but a method to estimate the amount in insect is not available. A method using irreversible inhibitors has been developed. Among the irreversible inhibitors tested, 7-(methylethoxyphosphinyloxy)-1-methylquinolinium iodide, chlorpyrifos-ethyl-oxon, and coumaphos-oxon were found to be sufficiently potent and specific. 相似文献
96.
José M. Quintero José M. Fournier José Ramos Manuel Benlloch 《Physiologia plantarum》1998,102(2):279-284
Twenty‐day‐old sunflower plants ( Helianthus annuus L. cv. Sun‐Gro 380) grown in nutrient solutions with different KCl levels were used to study the effects of K+ status of the root and of abcisic acid (ABA) on the exudation rate (Jv ), the hydraulic conductivity of the root (Lp ), the fluxes of exuded K+ and Na+ (JK and JNa ), and the gradient of osmotic pressure between the xylem and the external medium. Jv and Lp increased in direct proportion to the K+ starvation of the root. Also addition of ABA (4 µ M ) at the onset of exudation in the external medium made Jv and Lp rise, and this effect also increased with the degree of K+ starvation. Similarly, K+ starvation and ABA promoted both the flux of exuded Na+ and the accumulation of Na+ in the root. We suggest that ABA acts as a regulating signal for the radial transport of water across the root, and that potassium may be an effector of this mechanism. 相似文献
97.
Stephane Fournier Patrick Taffé Dragana Radovanovic Erik Von Elm Beata Morawiec Jean-Christophe Stauffer Paul Erne Ahmed Beggah Pierre Monney Patrizio Pascale Juan-Fernando Iglesias Eric Eeckhout Olivier Muller 《PloS one》2015,10(3)
Background
Different studies have shown circadian variation of ischemic burden among patients with ST-Elevation Myocardial Infarction (STEMI), but with controversial results. The aim of this study was to analyze circadian variation of myocardial infarction size and in-hospital mortality in a large multicenter registry.Methods
This retrospective, registry-based study was based on data from AMIS Plus, a large multicenter Swiss registry of patients who suffered myocardial infarction between 1999 and 2013. Peak creatine kinase (CK) was used as a proxy measure for myocardial infarction size. Associations between peak CK, in-hospital mortality, and the time of day at symptom onset were modelled using polynomial-harmonic regression methods.Results
6,223 STEMI patients were admitted to 82 acute-care hospitals in Switzerland and treated with primary angioplasty within six hours of symptom onset. Only the 24-hour harmonic was significantly associated with peak CK (p = 0.0001). The maximum average peak CK value (2,315 U/L) was for patients with symptom onset at 23:00, whereas the minimum average (2,017 U/L) was for onset at 11:00. The amplitude of variation was 298 U/L. In addition, no correlation was observed between ischemic time and circadian peak CK variation. Of the 6,223 patients, 223 (3.58%) died during index hospitalization. Remarkably, only the 24-hour harmonic was significantly associated with in-hospital mortality. The risk of death from STEMI was highest for patients with symptom onset at 00:00 and lowest for those with onset at 12:00.Discussion
As a part of this first large study of STEMI patients treated with primary angioplasty in Swiss hospitals, investigations confirmed a circadian pattern to both peak CK and in-hospital mortality which were independent of total ischemic time. Accordingly, this study proposes that symptom onset time be incorporated as a prognosis factor in patients with myocardial infarction. 相似文献98.
99.
Claude Saint-Ruf Meriem Garfa-Traoré Valérie Collin Corinne Cordier Christine Franceschi Ivan Matic 《Journal of bacteriology》2014,196(17):3059-3073
The evolutionary success of bacteria depends greatly on their capacity to continually generate phenotypic diversity. Structured environments are particularly favorable for diversification because of attenuated clonal interference, which renders selective sweeps nearly impossible and enhances opportunities for adaptive radiation. We examined at the microscale level the emergence and the spatial and temporal dynamics of phenotypic diversity and their underlying causes in Escherichia coli colonies. An important dynamic heterogeneity in the growth, metabolic activity, morphology, gene expression patterns, stress response induction, and death patterns among cells within colonies was observed. Genetic analysis indicated that the phenotypic variation resulted mostly from mutations and that indole production, oxidative stress, and the RpoS-regulated general stress response played an important role in the generation of diversity. We observed the emergence and persistence of phenotypic variants within single colonies that exhibited variable fitness compared to the parental strain. Some variants showed improved capacity to produce biofilms, whereas others were able to use different nutrients or to tolerate antibiotics or oxidative stress. Taken together, our data show that bacterial colonies provide an ecological opportunity for the generation and maintenance of vast phenotypic diversity, which may increase the probability of population survival in unpredictable environments. 相似文献
100.
Huei-Mei Hsieh Chun-Ru Lin Mei-Jane Fang Jack D. Rogers Jacques Fournier Christian Lechat Yu-Ming Ju 《Molecular phylogenetics and evolution》2010,54(3):957-969
To infer the phylogenetic relationships of Xylaria species associated with termite nests within the genus Xylaria and among genera of the subfamily Xylarioideae, β-tubulin, RPB2, and α-actin sequences of 131 cultures of 114 species from Xylaria and 11 other genera of the subfamily were analyzed. These 11 genera included Astrocystis, Amphirosellinia, Discoxylaria, Entoleuca, Euepixylon, Kretzschmaria, Nemania, Podosordaria, Poronia, Rosellinia, and Stilbohypoxylon. We showed that Xylaria species were distributed among three major clades, TE, HY, and PO, with clade TE—an equivalent of the subgenus Pseudoxylaria—encompassing exclusively those species associated with termite nests and the other two clades containing those associated with substrates other than termite nests. Xylaria appears to be a paraphyletic genus, with most of the 11 genera submerged within it. Podosordaria and Poronia, which formed a distinct clade, apparently diverged from Xylaria and the other genera early. Species of Entoleuca, Euepixylon, Nemania, and Rosellinia constituted clade NR, a major clade sister to clade PO, while those of Kretzschmaria were inserted within clade HY and those of Astrocystis, Amphirosellinia, Discoxylaria, and Stilbohypoxylon were within clade PO. 相似文献