Epitope extraction technique using a proteolytic magnetic reactor combined with Fourier-transform ion cyclotron resonance mass spectrometry as a tool for the screening of potential vaccine lead peptides

Epitope extraction technique is based on the specific digestion of a target protein followed by immunoaffinity isolation of a specific recognition peptide. This technique, in combination with mass spectrometry, has been efficiently used for epitope identification. The major goal of this work was to utilize newly developed enzyme and immunoaffinity magnetic reactors for the epitope extraction procedure and confirm the efficiency of this improved system for epitope screening of proteins. Alginic acid-coated magnetite microparticles with immobilized TPCK-trypsin provided high working efficiency with low non-specific adsorption, digestion time in minutes and low frequency of missed cleavages. The sensitivity and specificity of tryptic fragmentation of the beta-amyloid-peptide Abeta (1-40) as a model polypeptide was confirmed by Fourier-transform ion cyclotron resonance mass spectrometry analysis. The Sepharose reactor or immunoaffinity magnetic reactors, both with anti-amyloid-beta monoclonal antibodies, were used for specific isolation and identification of target peptides. In this way, the epitope extraction technique combined with mass spectrometric analysis is shown to be an excellent base for molecular screening of potential vaccine lead proteins.     

CoFe2O4/SiO2 nanocomposites by thermal decomposition of some complex combinations embedded in hybrid silica gels

The study reports the preparation of CoFe₂O₄/SiO₂ nanocomposites by a new modified sol–gel method starting from cobalt nitrate, iron nitrate, and diols: 1,2-ethanediol (EG), 1,3-propanediol (1,3PG), and tetraethylorthosilicate (TEOS), for final compositions of 30 %CoFe₂O₄/70 %SiO₂ and 50 %CoFe₂O₄/50 %SiO₂. The method is based on the formation of a Co(II), Fe(III)—carboxylate precursors mixture, during the redox reaction between the NO ₃ ^? ion and the diol (~140 °C) within the silica gels. The thermal decomposition of these complex combinations takes place at ~300 °C leading to the corresponding amorphous metal oxides within the pores of the hybrid gels. Depending on the subsequent thermal treatment, CoFe₂O₄ can be obtained as single phase or in a mixture with Co₂SiO₄. The CoFe₂O₄ crystallites sizes are in the nanometer range (3–10 nm). The obtained nanocomposites have a hard magnet behavior, as a result of the high anisotropy of CoFe₂O₄ having large hysteresis cycles.     

Evidence for nontermination of rotational bands in 74Kr

Three rotational bands in 74Kr were studied up to (in one case one transition short of) the maximum spin I(max) of their respective single-particle configurations. Their lifetimes have been determined using the Doppler-shift attenuation method. The deduced transition quadrupole moments reveal a modest decrease, but far from a complete loss of collectivity at the maximum spin I(max). This feature, together with the results of mean field calculations, indicates that the observed bands do not terminate at I = I(max).     

Bifunctional, conjugated oligomers for orthogonal self-assembly: selectivity varies from planar substrates to nanoparticles

A diphenylacetylene containing two different end groups (isonitrile and thioacetate) was synthesized, showing that the chemistry used to install each end group is compatible with that of the others. The isonitrile group binds preferentially to platinum, and the thiol group binds preferentially to gold. However, the selectivity was different when nanoparticles were compared to planar substrates.     

Influence of key parameters on the morphology of ethylcellulose microcapsules prepared via room-temperature spray drying

In this contribution, the morphology of ethylcellulose (EC) microspheres prepared with a room-temperature spray-drying technique is examined as a function of solution concentration, nozzle-to-target distance, and choice of solvent. Additionally, to determine the morphology of EC microspheres in the presence of an aqueous encapsulated material, a series of encapsulation measurements was conducted using hydrogen peroxide solution as the core component. It was observed that highly concentrated EC solutions lead to the formation of tail-like fibers adjacent to the sprayed microcapsules because of the high viscosity of solutions. Furthermore, when the solutions are sprayed from relatively short nozzle-to-target distances, porous EC films are formed on the target surface along with the EC microspheres. Three nozzle-to-target distances were tested (38, 69, and 115 cm), and the optimal one was found to be 115 cm. To determine how and to what extent the solvent used in room-temperature spray-drying experiments affects the morphology of resultant microspheres, EC was dissolved in either acetone or dichloromethane (DCM), and sprayed from the resultant solutions. While microcapsules prepared from the EC-in-DCM system exhibit even, but porous wall surfaces, microspheres prepared from the EC-in-acetone solution display irregular, but cavity-free wall-surfaces. Finally, as opposed to the pure EC capsules, the ones containing H₂O₂ solution exhibit very smooth wall surfaces; this effect was attributed to the plasticizing effect that the aqueous solution has on the ethylcellulose macromolecules.     

The Minimax Equality; Sufficient and Necessary Conditions

The paper produces new versions of the minimax theorem based on original conditions. Moreover, we investigate not only the sufficiency, but also the necessity of such conditions. The proofs are very simple and preclude any topological technique.     

Organic analysis with a new Ag(+)-selective membrane electrode

A new Ag(+)-selective membrane electrode obtained by impregnating a graphite rod (attached to the end of a Teflon tube) with the silver(I) chelate of 1-(2',3',5'-tri-O-benzoyl-beta-D-ribofuranosyl)-4-thioxo-5-methylthio-6-azauracil dissolved in chloroform gives a stable and reproducible response to silver in the 10(-1)-10(-5)M range with a slope of 60 mV/decade. A new method for determination of some beta-chlorovinyl ketones is based on use of the electrode in potentiometric titration of the chloride displaced by tertiary amines from beta-chlorovinyl ketones in forming the corresponding quaternary ammonium salts.     

Mass spectrometric approaches for elucidation of antigenantibody recognition structures in molecular immunology

Mass spectrometric approaches have recently gained increasing access to molecular immunology and several methods have been developed that enable detailed chemical structure identification of antigen-antibody interactions. Selective proteolytic digestion and MS-peptide mapping (epitope excision) has been successfully employed for epitope identification of protein antigens. In addition, "affinity proteomics" using partial epitope excision has been developed as an approach with unprecedented selectivity for direct protein identification from biological material. The potential of these methods is illustrated by the elucidation of a beta-amyloid plaque-specific epitope recognized by therapeutic antibodies from transgenic mouse models of Alzheimer's disease. Using an immobilized antigen and antibody-proteolytic digestion and analysis by high resolution Fourier transform ion cyclotron resonance mass spectrometry has lead to a new approach for the identification of antibody paratope structures (paratope-excision; "parex-prot"). In this method, high resolution MS-peptide data at the low ppm level are required for direct identification of paratopes using protein databases. Mass spectrometric epitope mapping and determination of "molecular antibody-recognition signatures" offer high potential, especially for the development of new molecular diagnostics and the evaluation of new vaccine lead structures.     

Studies regarding the formation from metal nitrates and diol of NiM 2 III O4 spinels, inside a silica matrix

The present study deals with preparation and characterization of spinel mixed oxide systems NiM ₂ ^III O₄, where M^III?=?Fe^III, Cr^III. In order to obtain 50% NiFe₂O₄/50% SiO₂ and 50% NiCr₂O₄/50% SiO₂ nanocomposite, we have used a versatile route based on the thermal decomposition inside the SiO₂ matrix, of some particular precursors, coordination compounds of the involved M^II and M^III cations with dicarboxylate ligands. The ligands form in the redox reaction between metal nitrates mixture and 1,3-propanediol at the heating around 140?°C of the gels (tetraethylorthosilicate?Cmetal nitrates?C1,3-propanediol?Cwater). The as-obtained precursors, embedded in silica gels, have been characterized by FT-IR spectrometry and thermal analysis. Both precursors thermally decompose up to 350?°C leading to the formation of the corresponding metal oxides inside the silica matrix. X-ray diffraction of the annealed powders have evidenced the formation of NiFe₂O₄ starting with 600?°C, and NiCr₂O₄ starting with 400?°C. This behavior can be explained by the fact that, by thermal decomposition of the Fe(III) carboxylate at 300?°C, the spinelic phase ??-Fe₂O₃ is formed, which interacts with the NiO, forming the ferrite nuclei. By thermal decomposition of chromium carboxylate, a nonstoichiometric chromium oxide (Cr₂O_3+x ) is formed. In the range 380?C400?°C, Cr₂O_3+x turns into Cr₂O₃ which immediately interacts with NiO leading to the formation of nickel chromites nuclei inside the pores of silica matrix. Both spinels have been obtained as nanocrystalites homogenously dispersed as resulted from XRD and TEM data.     

Predicting stable configurations of coalitions in cooperative games and exchange economies

Uniform competitive solutions are stable configurations of proposals predicting coalition formation and effective payoffs. Such “solutions” exist for almost all properly defined cooperative games and, therefore, can be proposed as substitute of the core. The new existence results obtained in the present paper concern also the case when the coalitional function of a game has empty values. All concepts and results are implemented in the competitive analysis of the exchange economies. Received: July 1997/Final version: February 2000