Chemical and immunochemical investigation of the lipopolysaccharides ofVibrio alginolyticus

A chemical and immunochemical study of the LPSs of the microorganismsVibrio alginolyticus (strains 1385–80, 945–80, and 2076–80) has been made. A difference in the monosaccharide composition of the LPSs of the strains studied has been shown. It had been established that the LPSs of strains 945–80 and 2076–80 possess a high serological specificity, while the LPS of strain 1385–80 differ serologically from them. A suggestion is made of the role of different monosaccharides in the formation of the immunochemical determinants of the LPSs of the strains studied.     

Comparative structural study of the lipopolysaccharides of Y. enterocolitica serovars 0:7.8 and 0:19.8

The lipopolysaccharides ofYersinia enterocolitica, serovars 0:7.8 (strain 106) and 0:19.8 (strain 842), isolated from the microbial mass by phenol-water extraction, contained residues of L-fucose, 6-deoxy-D-gulose, D-mannose, D-galactose, D-glucose, D- and L-glycero-D-mannoheptoses, N-acetyl-D-glucosamine, N-acetyl-D-galactosamine, and 2-keto-3-deoxyoctonic acid (KDO). The polysaccharides obtained by mild acid hydrolysis of the lipopolysaccharides followed by gel filtration on Sephadex G-50 were a mixture of the O-specific polysaccharide and the core, which could not be separated even by repeated rechromatography because of the comparability of their molecular masses. On the basis of the results of monosaccharide analysis, methylation, Smith degradation, and partial hydrolysis, a structure has been suggested for the repeating unit of the O-specific polysaccharides of the lipopolysaccharides ofY. enterocolitica of the serovars studied. Pacific Ocean Institute of Bioorganic Chemistry, Far Eastern Branch, USSR Academy of Sciences, Vladivostok. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 763–770, November–December, 1989.     

Comparative structural study of the lipopolysaccharides of Y. enterocolitica serovars 0:7.8 and 0:19.8

The lipopolysaccharides ofYersinia enterocolitica, serovars 0:7.8 (strain 106) and 0:19.8 (strain 842), isolated from the microbial mass by phenol-water extraction, contained residues of L-fucose, 6-deoxy-D-gulose, D-mannose, D-galactose, D-glucose, D- and L-glycero-D-mannoheptoses, N-acetyl-D-glucosamine, N-acetyl-D-galactosamine, and 2-keto-3-deoxyoctonic acid (KDO). The polysaccharides obtained by mild acid hydrolysis of the lipopolysaccharides followed by gel filtration on Sephadex G-50 were a mixture of the O-specific polysaccharide and the core, which could not be separated even by repeated rechromatography because of the comparability of their molecular masses. On the basis of the results of monosaccharide analysis, methylation, Smith degradation, and partial hydrolysis, a structure has been suggested for the repeating unit of the O-specific polysaccharides of the lipopolysaccharides ofY. enterocolitica of the serovars studied.Pacific Ocean Institute of Bioorganic Chemistry, Far Eastern Branch, USSR Academy of Sciences, Vladivostok. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 763–770, November–December, 1989.     

Chemical and immunochemical investigation of the lipopolysaccharides ofVibrio alginolyticus

A chemical and immunochemical study of the LPSs of the microorganismsVibrio alginolyticus (strains 1385–80, 945–80, and 2076–80) has been made. A difference in the monosaccharide composition of the LPSs of the strains studied has been shown. It had been established that the LPSs of strains 945–80 and 2076–80 possess a high serological specificity, while the LPS of strain 1385–80 differ serologically from them. A suggestion is made of the role of different monosaccharides in the formation of the immunochemical determinants of the LPSs of the strains studied.Pacific Ocean Institute of Bioorganic Chemistry of the Far-Eastern Scientific Center of the USSR Academy of Sciences, Vladivostok. Translated from Khimiya Priorodnykh Soedinenii, No. 5, pp. 652–657, September–October, 1987.     

Synthesis and characterization of preferentially oriented (1 0 0) Pt nanowires

Two types of platinum deposits were obtained by potentiostatic deposition onto Ti substrates, namely platinum black (Pt B) and platinum nanowires (Pt NW) with the latter being achieved through a porous anodic aluminum oxide (AAO) membrane at the solution/substrate interface. Surface characterization of these deposits was performed using scanning electron microscopy (SEM) and cyclic voltammetry (CV) in sulphuric acid solution. Surface properties for Pt NW revealed a predominant presence of (1 0 0) crystallographic planes, not present in Pt B deposit grown in the same conditions. Also, Pt NW exhibits an increased resistance to electrochemically active surface area (EASA) loss upon potential cycling in acidic solution, as compared to Pt B.     

Synthesis and immunochemical characterization of S-linked glycoconjugate vaccines against Candida albicans

Replacement of the glycosidic oxygen atom by a sulphur atom is a promising technique for creating glycoconjugates with increased resistance to hydrolysis by endogenous glycosidases. The synthesis and antigenic properties of two distinct (1-->2)-beta-mannan trisaccharides with inter residue-S-linked mannopyranose residues are described. Syntheses were based on an oxidation-reduction strategy to construct the O-linked beta-mannopyranoside bonds and a SN2 inversion to provide 1-thio-beta-mannopyranoside residues. Subsequently the allyl trisaccharide glycosides were subjected to photo addition with cysteine amine and coupled to tetanus toxoid and bovine serum albumin with good efficiency via an adipic acid tether. Rabbit immunization studies revealed that the antibodies elicited by the two glycoconjugates were able to recognize the corresponding O-linked trisaccharide epitope conjugated to BSA and the native cell wall antigen of Candida albicans.     

Polymorphism and luminescence properties of CMONS organic crystals: bulk crystals and nanocrystals confined in gel-glasses

In order to compare the polymorphism of 1-cyano-1-(4-nitrophenyl)-2-(4-methoxyphenyl)ethene CMONS crystallized in solutions to that of CMONS nanocrystals grown in the pores of dense sol-gel matrices, we have first studied the CMONS polymorphism in various solvents which were then used in the nanocrystallization processes. The different polymorphs were characterized by differential scanning calorimetry, X-ray diffraction and absorption as well as luminescence spectroscopies. The differences observed between CMONS powders and CMONS nanocrystals illustrate the role played by the silicate matrices on the polymorphism of CMONS. This matrix effect would be used to stabilize a particular polymorph of an organic phase and thus to adjust the optical properties of the nanocomposite hybrid organic–inorganic material.     

Lipids and lipopolysaccharides of the genusFlavobacterium

The fatty acid compositions of the free lipids of three strains and the monosaccharide compositions of the lipopolysaccharides of four strains of new species of microorganisms of the genusFlavobacterium have been studied. The acidic nature of the polysaccharides of the LPSs of the microorganisms studied has been shown.     

Application of capillary electrophoresis- electrospray-mass spectrometry to the separation and characterization of isomeric lipopolysaccharides of Neisseria meningitidis

A capillary electrophoresis-electrospray-mass spectrometry technique for the characterization of lipopolysaccharides (LPSs) was developed, permitting the separation of trace-level O-deacylated LPS isoforms for subsequent structural characterization using tandem mass spectrometry (MS/MS). The separation buffer and electrospray interface were optimized first using O-deacylated LPS samples from large-scale preparations. It was found that with microelectrospray or sheath-solution interface, we could separate LPS in anionic forms and detect them using either negative or positive ion mode MS. For negative ion detection mode MS, 30 mM morpholine with addition of 5% v/v methanol was employed as separation buffer. When positive ion detection mode MS was required, 10 mM ammonium acetate with addition of 5% methanol was used as separation buffer. The structural assignments obtained from MS/MS and capillary zone electrophoresis-electrospray-MS (CZE-ESMS) analyses enabled the identification of isomeric glycoforms. Application of this technique to the analysis of LPS from the galE mutants of Neisseria meningitidis strain BZ157 B5+ revealed the presence of isomeric glycoforms, in which the location of a functional group phosphoethanolamine was found to be in either inner core or lipid A-OH regions. The described technique was also applied to the analysis of LPS samples from the galE mutant of N. meningitidis strains F1576 A4+ and A4-. The occurrence of isomeric LPS glycoforms differing by the location or presence of neutral sugar residues, such as hexoses, can also be characterized using MS/MS.     

Carbonyltungsten(0) complexes of acryloylferrocene: Synthesis and characterization

Photolysis of hexacarbonyltungsten(0) in the presence of acryloylferrocene in n-hexane solution at 10 °C yields pentacarbonyl(η²-acryloylferrocene)tungsten(0) (1) as the only photo-substitution product, different from the general reaction pattern observed for the Group 6 metal carbonyls with other olefins. W(CO)₅(η²-acryloylferrocene) (1) decomposes in solution to the parent hexacarbonyltungsten(0) and free acryloylferrocene. Trimethylphosphite was introduced as ligand into the molecule to increase the stability. The photolysis of pentacarbonyl(trimethylphosphite)tungsten(0) in the presence of acryloylferrocene in n-hexane solution at 10 °C yields only cis-W(CO)₄[P(OCH₃)₃](η²-acryloylferrocene) (2) as the monosubstitution product. Both η²-acryloylferrocene complexes (1 and 2) could be isolated and characterized by MS, IR and NMR spectroscopy. The trimethylphosphite complex (2) is found to be even less stable than W(CO)₅(η²-acryloylferrocene) (1).     

Modeling of reactive systems in twin-screw extrusion: challenges and applications

Reactive extrusion processes involve the difficulties of mastering classical polymer processes, such as twin-screw extrusion for example, and the problems of controlling a chemical reaction in very specific conditions (high-viscosity medium, high temperatures, short residence times). Therefore, it is often very difficult to intuitively understand all the aspects of the process and to clarify the complex interactions between the numerous variables, and then to properly design and optimize the industrial process. Numerical modeling can be a very efficient tool to overcome these difficulties. However, it remains a real challenge, as it necessitates to couple flow simulation in complex geometry, reaction kinetics and evolutionary rheological behavior. Moreover, the information needed is sometimes difficult to obtain with the required accuracy. After a general presentation of the principles of the different reactive extrusion modeling methodologies, we will focus on the models we developed, based on continuum mechanics. Different examples of applications are presented for illustrating the interest of this method. To cite this article: B. Vergnes et al., C. R. Chimie 9 (2006).     

(Liquid + liquid) equilibria of the quaternary system methanol + isooctane + cyclohexane + benzene at T = 303.15 K

Tie line data of the ternary system {methanol + isooctane + cyclohexane} were obtained at T = 303.15 K. A quaternary system containing these three compounds and benzene was also studied at the same temperature, while data for {methanol + benzene + cyclohexane} and {methanol + benzene + isooctane} were taken from literature. In order to obtain the binodal surface of the quaternary system, four quaternary sectional planes with several cyclohexane/isooctane ratios were studied. The distribution of benzene between both phases was also analysed. Ternary experimental results were correlated with the UNIQUAC and NRTL equations and compared with predictions using the UNIFAC group contribution method.     

Differential detergent fractionation of isolated hepatocytes: Biochemical,immunochemical and two-dimensional gel electrophoresis characterization of cytoskeletal and noncytoskeletal compartments

Two-dimensional (2-D) gel electrophoresis is often used in toxicologic and metabolic studies to assess treatment- or stage-specific changes in protein synthesis, degradation or posttranslational modification. When combined with cell fractionation studies the detectability of low abundance proteins is enhanced, and changes in subcellular distribution of proteins can also be monitored. Detergent fractionation is a simpler alternative to differential pelleting, which partitions cellular constituents into functionally distinct populations while preserving cytoskeletal integrity. We defined and characterized a differential detergent fractionation (DDF) protocol to enable protein dynamics in cytoskeletal and noncytoskeletal compartments of isolated hepatocytes to be monitored simultaneously. Rat hepatocytes were maintained in suspension culture and fractionated by sequential extraction with detergentcontaining buffers (digitonin/EDTA, Triton/EDTA, Tween/deoxycholate). DDF reproducibly yielded four electrophoretically distinct fractions enriched in cytosolic, membrane-organelle, nuclear membrane and cytoskeletal-matrix markers, respectively. Immunoblotting with over 20 different antibodies corroborated the selectivity of fractionation and was used to characterize the distribution profiles of cytoskeletal (actin, tubulins, cytokeratins, vinculin, myosin, desmoplakins, fodrin, nuclear lamins) and noncytoskeletal proteins (heat-shock 70 proteins, glutathione-S-transferase, calpains, carbamoyl phosphate synthetase, etc.), as well as to identify spots in 2-D gels. Detergent buffers were compatible with equilibrium or nonequilibrium 2-D gel electrophoretic analysis. Extensive 2-D maps of acidic and basic proteins in each fraction were generated along with a tabular listing of M_r and pI. Thus, DDF reproducibly partitions hepatocytic proteins into functionally distinct cytoskeletal and noncytoskeletal compartments that are readily analyzed by 2-D gel electrophoresis. DDF is simple, applicable to use with other cell types or culture systems and is especially useful when biomaterial is limited (i.e., clinical studies).     

Policy on characterization of antibodies used in immunochemical methods of analysis for mycotoxins and phycotoxins

The purpose of this document is to provide a policy on antibody characterization for conducting AOAC collaborative studies for immunochemical methods submitted for AOAC Official Methods Program status. The policy defines recommended information and characteristics to be provided by the Study Director, in the protocol of the collaborative study, for approval by AOAC. The document specifies parameters for characterization of antibodies used as biological reagent in the protocol of validation of immunochemical methods for the determination of mycotoxins and phycotoxins. These recommendations are applicable to the validation of any method, whether proprietary or nonproprietary, that is submitted to AOAC for Official Methods of Analysis status recognition.     

Isobaric vapor–liquid equilibria for the quaternary reactive system: Ethanol + water + ethyl lactate + lactic acid at 101.33 kPa

Isobaric vapor–liquid equilibrium (VLE) data of the reactive quaternary system ethanol (1) + water (2) + ethyl lactate (3) + lactic acid (4) have been determined experimentally. Additionally, the reaction equilibrium constant was calculated for each VLE experimental data. The experimental VLE data were correlated using the UNIQUAC equation to describe the chemical and phase equilibria simultaneously. For some of the non-reactive binary systems, UNIQUAC binary interaction parameters were obtained from the literature. The rest of the binary UNIQUAC parameters were obtained by correlating the experimental quaternary VLE data obtained in this work. A maximum pressure azeotrope at high water concentration for the binary reactive system ethyl lactate + water has been calculated.     

Par-delà la synthèse : l’auto-organisation

The evolution of the universe from the particle to the thinking organism has taken place through self-organization. Chemistry has a major role to play in understanding these processes leading to the generation of complex matter. Chemistry has developed a highly powerful molecular synthetic chemistry, mastering the combination and recombination of atoms into increasingly complex molecules through selective chemical reactions. Supramolecular chemistry is harnessing intermolecular forces for the generation of informed supramolecular systems and processes through supramolecular synthetic chemistry implementing molecular information carried by electromagnetic interactions. Supramolecular chemistry has been actively exploring systems undergoing self-organization, i.e., systems capable of spontaneously generating well-defined functional supramolecular architectures by self-assembly from their components, under the control of interactional molecular recognition events, thus behaving as programmed chemical systems. Molecular chemistry may similarly take advantage of the selectivity of covalent reactions to assemble complex molecular architectures through self-organization processes implementing functional molecular recognition. Supramolecular/non-covalent and molecular/covalent SELF-ORGANIZATION may thus be considered as the ULTIMATE SYNTHETIC CHEMISTRY, whereby chemical objects at both levels are generated on the basis of recognition processes involving either interactional or reactional features. Illustrations from the supramolecular domain will serve as illustrations. Supramolecular entities as well as molecules containing reversible bonds are able to undergo a continuous change in constitution by reorganization and exchange of building blocks. This capability defines a Constitutional Dynamic Chemistry (CDC) on both the molecular and supramolecular levels. CDC introduces a paradigm shift with respect to constitutionally static chemistry. It takes advantage of dynamic constitutional diversity to allow variation and selection and thus leads towards the emergence of adaptive and evolutive chemistry.