Study of the interaction of antiplasmodial strychnine derivatives with the glycine receptor

in European Journal of Pharmacology (2006), 530(1-2), 15-22

Strychnos icaja Baill. (Loganiaccae) is a liana found in Central Africa known to be an arrow and ordeal poison but also used by traditional medicine to treat malaria. Recently, many dimeric or trimeric ... [more ▼]

Strychnos icaja Baill. (Loganiaccae) is a liana found in Central Africa known to be an arrow and ordeal poison but also used by traditional medicine to treat malaria. Recently, many dimeric or trimeric indolomonoterpenic alkaloids with antiplasmodial properties have been isolated from its rootbark. Since these alkaloids are derivatives of strychnine, it was important, in view of their potential use as antimalarial drugs, to assess their possible convulsant strychnine-like properties. In that regard, their interaction with the strychnine-sensitive glycine receptor was investigated by whole-cell patch-clamp recordings on glycine-gated currents in mouse spinal cord neurons in culture and by [H-3]strychnine competition assays on membranes from adult rat spinal cord. These experiments were carried out on sungucine (leading compound of the chemical class) and on the antiplasmodial strychnogucine B (dimeric) and strychnohexamine (trimeric). In comparison with strychnine, all compounds interact with a very poor efficacy and only at concentrations > I mu M with both [H-3]strychnine binding and glycine-gated currents. Furthermore, the effects of strychnine and protostrychnine, a monomeric alkaloid (without antiplasmodial activity) also isolated from S. icaja and differing from strychnine only by a cycle opening, were compared in the same way. The weak interaction of protostrychnine confirms the importance of the G cycle ring structure in strychnine for its binding to the glycine receptor and its antagonist properties. (c) 2005 Elsevier B.V. All rights reserved. [less ▲]

Study of the interactions between the late stage proteins of Escherichia coli divisome assembly.

Poster (2011, August 16)

Study of the interactive effect of temperature and pH on exopolysaccharide 3 production by Enterobacter A47 using multivariate statistical analysis

in Bioresource Technology (2012)

Study of the Io footprint short timescale variability

Poster (2006, May)

The electromagnetic interaction between Io and Jupiter leads to single or multiple auroral UV spots in both jovian hemispheres. This study concentrates on short timescale (~1 min) morphological changes of ... [more ▼]

The electromagnetic interaction between Io and Jupiter leads to single or multiple auroral UV spots in both jovian hemispheres. This study concentrates on short timescale (~1 min) morphological changes of the footprints. In order to achieve a sufficient time resolution, we use the time-tag mode of the HST/STIS instrument. This allows us to account for the spots blurring due to the rapid evolution of the jovian magnetic field lines. In addition to the spots motion, our analysis focuses on the spots brightness variations and on the correlation between these variations. The characterization of the parameters herein gives rise to both clues and new questions on the mechanisms that induce the precipitation of energetic electrons. [less ▲]

STUDY OF THE LIPIDS FROM IVY (HEDERA-HELIX L) - IDENTIFICATION OF ISOMERIC MONOUNSATURATED FATTY-ACIDS

in Revue Française des Corps Gras (1987), 34(9), 407-411

In the present study, fatty acids from Hedera helix L. are identified and measured. After epoxidation, monoenic fatty methyl esters (81.6 %) of the total fatty acids) are separated by mean of very ... [more ▼]

In the present study, fatty acids from Hedera helix L. are identified and measured. After epoxidation, monoenic fatty methyl esters (81.6 %) of the total fatty acids) are separated by mean of very resolutive capillary columns with cyanopropylsiloxane stationnary phase. ldentification are achieved with the help of GC-MS. Electron impact and more conveniently chemical ionisation (NHi are both used. Observation of characteristic mass fragments from fatty epoxides allow us to identify three octadecenoic positionnal isomers . petroselinic acid (C 1 8. 1 delta 6 cis), oleic acid (C18:1 delta 9 cis) and vaccenic acid (C18:1 delta 11 c i s ) . This last one i s rare in vegetable o i l s . [less ▲]

Study of the liquid fraction and thermophysical properties of semi-solid steels and application to the simulation of inductive heating for thixoforming

in Bananic, Dorel (Ed.) Advanced Methods in Material Forming (2005)

The thixoforming of steels is so complex that it requires more investigations regarding both the materials and the technical tools dedicated to the elaboration of the process. In this paper we will show ... [more ▼]

The thixoforming of steels is so complex that it requires more investigations regarding both the materials and the technical tools dedicated to the elaboration of the process. In this paper we will show the experimental determination of appropriate solidus-liquidus interval on eight different steel compositions. This critical parameter was obtained using Differential Scanning Calorimetry. The paper also presents the results of thermophysical property determination. These parameters are important for the inductive heating phase of a semi-solid forming (SSF) process. Thanks to the simulations of the inductive heating process, the other main results consist on the developments of the heating techniques that are suitable for the achieving of the sine qua none condition to the semi-solid process, which is the uniform temperature distribution in the reheated billet. [less ▲]

Study of the mechanism of direct laser desorption/ionisation for some small organic molecules (M < 400 daltons)

in Rapid Communications in Mass Spectrometry : RCM (1999), 13(23), 2302-2304

Aspects of direct laser desorption/ionisation have been studied for three molecules, aminotriazole (positive ion), dinoterb and ioxynil (negative ion). The samples are deposited on metallic substrates ... [more ▼]

Aspects of direct laser desorption/ionisation have been studied for three molecules, aminotriazole (positive ion), dinoterb and ioxynil (negative ion). The samples are deposited on metallic substrates, and a nitrogen laser is used for desorption/ionisation; ion yields are measured with a time-of-flight mass spectrometer, Previous work had shown that ion yields can strongly vary from one substrate to another, and that this variation does not reflect the (calculated) metal surface temperatures. New results obtained in this work indicate that the desorption/ionisation mechanism is linked to the physical state of the substrate surface. Copyright (C) 1999 John Wiley & Sons, Ltd. [less ▲]

Study of the Mechanism of the Coal Analysis by Laser-Induced Breakdown Spectroscopy

Doctoral thesis (2010)

The elemental composition of the coal is one of the necessary data for the thermal calculation and combustion adjustment of the boiler. The traditional coal analysis methods are usally off-line and ... [more ▼]

The elemental composition of the coal is one of the necessary data for the thermal calculation and combustion adjustment of the boiler. The traditional coal analysis methods are usally off-line and couldn’t offer the real-time data of the coal, so they couldn’t satisfy the needs of the combustion adjustment and accident analysis of the boiler and have a lot of limitations. Therefore, it is necessary to develop a new technology which can analyze the coal rapidly. Laser-induced breakdown spectroscopy (LIBS) is a new technology which has the advantages of the quick and multi-elemental analysis, thus it can be applied for the coal analysis. The theoretical analysis and experimental research are used in the thesis, and they will provide the experimental basis and theoretical foundation for the coal analysis by LIBS. The current researches both at home and abroad of the applications of the LIBS technique on the coal-fired field are analyzed in this thesis, and the key problems of the current researches are summarized. The mechanism of the production and evolution of the plasma of the coal is very important. The amounts of the main elements which need to be measured of the coal are more than ten, and it is hard to achieve the multi-elemental analysis. On the other hand, the C, H and O elements are hard to excite and ionize, but the canlibration and quantitative analysis of them are most important. However, these contents are closely related to the practical application of the LIBS technique on the coal analysis. According to these key problems, a series of researches will be carried on in this thesis: The LIBS set-up for the coal analysis is established, and the typical Shenhua bituminous coal is chosen as the object. The time evolution process of the continuous spectrum and the atomic emission line of C I 247.9nm are analyzed, and the formation mechanisms of the spectral lines in each stages from the production to the annihilation of the plasma of the coal are discussed. Moreover, the difference of the evolution processes between the plasmas from the coal and the copper is compared, and the influence of the volatile in the coal to the plasma is discussed. These researches provide the experimental platform and theoretical basis for designing the coal analysis instrumentation by LIBS. The influence of the excitation and ionization property of the elements on the plasma is analyzed. The suitable delay time and gate width are selected for the purpose of the multi-elemental analysis of the coal by means of a series of experimental researches on the time evolution processes of different emission lines. The experiments on the coal are performed by changing the parameters including the laser energy, the lens focal plane position and the number of averages, and the influence of the parameters on the intensity and repeatability of the emission lines are analyzed. On this basis, the optimum parameters are determined. Four bituminous coals from different mines in China are checked by using the optimum parameters, and the result shows that the line intensities are strong and the reproducibilities are high. These researches supply the experimental foundation and technical parameters for designing the coal analysis instrumentation by LIBS. The C, H and O elements in the coal are closely related to the combustion, but the sensitivities of their emission lines are low and the results of the calibration curves are not good. In view of these problems, the atomic line of Si I 288.2nm is chosen as the internal standard line, and the internal standard curves of C I 247.9nm, H I 656.3nm and O I 777.4nm are obtained and the calibration results are good. Moreover, in order to avoid the disturbtion of the analysis of the O element from the air, the method of blowing the argon is used in this thesis. The result shows that the interference to the O element is inexistence and the line intensities of the coal are stronger when using the argon. It is found that the calibration results of the C, H and O elements in argon are better than in air. These researches provide the proper calibration method for the quantitative analysis of the C, H and O elements in the coal. The quantitative analysis is the final purpose of the LIBS technique that applied to the coal-fired field. The conventional quantitative analysis methods are analyzed. The quantitative analysis of the minor elements in the coal is completed by using the calibration curve method, and the result shows the accuracies are high. The quantitative analysis of the C, H and O elements in coal is finished by using the internal standard curve method, and the result shows the accuracies are just passable. The quantitative analysis of the C elment in the coal ash is accomplished by using the internal standard curve method too, and the result shows that the LIBS technique has the applicability for the measurement of the C elment in the coal ashes which come from different coal samples. These researches supply the database for designing the coal analysis instrumentation by LIBS. Finally, the research works in this thesis are summaried and some advices are given for the further research works. [less ▲]

Study of the microbial diversity in vacuum-packed chilled beef from different origins through a metagenomics approach

Poster (2012, April)

Despite a diverse initial microbial population, bacterial spoilage of vacuum-packed chilled beef is mainly due to the growth of psychrotrophic bacteria. The study of the microflora of vacuum-packed ... [more ▼]

Despite a diverse initial microbial population, bacterial spoilage of vacuum-packed chilled beef is mainly due to the growth of psychrotrophic bacteria. The study of the microflora of vacuum-packed chilled beef remains a challenge since some members of the microflora may be missed or not identified by cultivation-based methods. The aim of this study was to evaluate the microbial diversity in eight batches of vacuum-packed chilled beef from different origins (Australia, Belgium, Brazil, Ireland and United Kingdom) by metagenomics. Longissimus dorsi muscle samples were homogenized and analysed in early and late stages of their shelf life by metagenomics. The metagenomic assays consisted in DNA extraction, 16S ribosomal RNA gene amplification, pyrosequencing and data analysis. All samples, except for two batches from Australia, presented a high microbial diversity in the beginning of their shelf life. Enterobacteriaceae, Pseudomonas, Burkholderia, Lactobacillus and Sterotrophomonas were some of the major bacteria identified at this stage of storage. The dominant flora (> 80 % of relative abundance) in two Australian batches was composed by Carnobacterium. At the end of the shelf life of the samples, a decrease in microbial diversity was observed in almost all batches. At this stage of storage, Carnobacterium, Lactobacillus, Lactococcus and Enterococcus were some of the major genera identified. Carnobacterium remained the dominant flora in the two Australian batches cited above, which could explain the long shelf life applicable to this meat (140 days) as some Carnobacterium strains induce a biopreservative effect especially by producing bacteriocins with a wide inhibition spectrum. Metagenomics showed to be a very useful tool to study the microbial population of a complex matrix such as meat since some of the identified genera such as Lactobacillus and Carnobacterium are known not to grow or to grow slowly in media commonly used for the isolation and cultivation of total viable counts. [less ▲]

A study of the mixing by PIV and PLIF in bioreactor of cells animal culture

Conference (2008, August 19)