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Molecules Used (molecule + used)
Selected AbstractsAnalysis of proteins stained by Alexa dyesELECTROPHORESIS, Issue 6 2004Shijun Huang Abstract Alexa dye staining of proteins is used for the fluorescence microscopy of single particles that are sometimes multimolecular protein complexes. To characterize the staining, post-staining determination must be made of which protein(s) in a complex have been Alexa-stained. The present communication describes the use of sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) for performing this determination. The Alexa-stained proteins are observed directly in gels by illumination with an ultraviolet transilluminator. The test multimolecular particle is bacteriophage T7. The protein capsid of T7 is a multimolecular complex that has both external and internal proteins. SDS-PAGE of Alexa-stained bacteriophage T7 produces fluorescent capsid proteins each of which usually comigrates with an unstained protein. However, one Alexa-induced modification of protein migration was observed by SDS-PAGE. Mass spectrometry shows that the protein with modified migration is the major protein of the outer shell of the T7 capsid. The procedures used are generally applicable. The distribution of Alexa staining among T7 capsid proteins depends on the size of the dye molecule used. The larger the dye molecule is, the greater the preference for external proteins. [source] Role of interfaces on the direct tunneling and the inelastic tunneling behaviors through metal/alkylsilane/silicon junctionsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 6 2006D. K. Aswal Abstract We studied the influence of the end group of the alkylsilane molecule used in Self Assembled Monolayer (SAM) in Silicon/SAM/Metal junctions. By Inelastic Electron Tunneling spectroscopy (IETS), we showed the formation of a covalent bond between the molecules and the gold electrode in the case of a thiol terminated alkylsilane. By electrical characterizations, we demonstrated that the thiol group at the interface avoids diffusion of gold into the molecule even for a 3 carbons chain. For this short molecule, we observed pure tunnel conduction with barrier height at the monolayer/Si and monolayer/Au interfaces found to be respectively 2.14 and 2.56 eV. These values were obtained using Simmons equation with an effective mass parameter m * = 0.16me (me = mass of the electron). This extends the demonstration of the excellent tunnel dielectric behavior of these organic monolayers down to 3 carbon atoms with a thiol/Au bond at the interface. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Historical review of sample preparation for chromatographic bioanalysis: pros and consDRUG DEVELOPMENT RESEARCH, Issue 3 2007Min S. Chang Abstract Sample preparation is a major task in a regulated bioanalytical laboratory. The sample preparation procedure significantly impacts assay throughput, data quality, analysis cost, and employee satisfaction. Therefore, selecting and optimizing an appropriate sample preparation method is essential for successful method development. Because of our recent expertise, this article is focused on sample preparation for high-performance liquid chromatography with mass spectrometric detection. Liquid chromatography with mass spectrometric detection (LC-MS) is the most common detection technique for small molecules used in regulated bioanalytical laboratories. The sample preparation technologies discussed are pre-extraction and post-extraction sample processing, protein precipitation (PPT), liquid,liquid extraction (LLE), offline solid-phase extraction (SPE), and online solid-phase extraction. Since all these techniques were in use for more than two decades, numerous applications and variations exist for each technique. We will not attempt to categorize each variation. Rather, the development history, a brief theoretical background, and selected references are presented. The strengths and the limitations of each method are discussed, including the throughput improvement potential. If available, illustrations from presentations at various meetings by our laboratory are used to clarify our opinion. Drug Dev Res 68:107,133, 2007. ©2007 Wiley-Liss, Inc. [source] The human skin/chick chorioallantoic membrane model accurately predicts the potency of cosmetic allergensEXPERIMENTAL DERMATOLOGY, Issue 4 2009Dan Slodownik Abstract:, The current standard method for predicting contact allergenicity is the murine local lymph node assay (LLNA). Public objection to the use of animals in testing of cosmetics makes the development of a system that does not use sentient animals highly desirable. The chorioallantoic membrane (CAM) of the chick egg has been extensively used for the growth of normal and transformed mammalian tissues. The CAM is not innervated, and embryos are sacrificed before the development of pain perception. The aim of this study was to determine whether the sensitization phase of contact dermatitis to known cosmetic allergens can be quantified using CAM-engrafted human skin and how these results compare with published EC3 data obtained with the LLNA. We studied six common molecules used in allergen testing and quantified migration of epidermal Langerhans cells (LC) as a measure of their allergic potency. All agents with known allergic potential induced statistically significant migration of LC. The data obtained correlated well with published data for these allergens generated using the LLNA test. The human-skin CAM model therefore has great potential as an inexpensive, non-radioactive, in vivo alternative to the LLNA, which does not require the use of sentient animals. In addition, this system has the advantage of testing the allergic response of human, rather than animal skin. [source] The impact of successive infections on the lung microenvironmentIMMUNOLOGY, Issue 4 2007Arnaud Didierlaurent Summary The effect of infection history on the immune response is ignored in most models of infectious disease and in preclinical vaccination studies. No one, however, is naïve and repeated microbial exposure, in particular during childhood, shapes the immune system to respond more efficiently later in life. Concurrent or sequential infections influence the immune response to secondary unrelated pathogens. The involvement of cross-reactive acquired immunity, in particular T-cell responses, is extensively documented. In this review, we discuss the impact of successive infections on the infected tissue itself, with a particular focus on the innate response of the respiratory tract, including a persistent alteration of (1) epithelial or macrophage expression of Toll-like receptors or adherence molecules used by subsequent bacteria to invade the host, (2) the responsiveness of macrophages and neutrophils and (3) the local cytokine milieu that affects the activation of local antigen-presenting cells and hence adaptive immunity to the next infection. We emphasize that such alterations not only occur during coinfection, but are maintained long after the initial pathogen is cleared. As innate responses are crucial to the fight against local pathogens but are also involved in the maintenance of the homeostasis of mucosal tissues, dysregulation of these responses by repeated infections is likely to have a major impact on the outcome of infectious or allergic disease. [source] A multilayered approach to approximating solute polarizationJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 5 2004Richard I. Maurer Abstract A hybrid multilayered "ONIOM"-type approach to solvation is presented in which the basic free energy of hydration is taken from the Poisson Boltzmann method and the contribution to the solute polarization is taken from a quantum mechanical implementation of the Born method. The method has been tested on the 52 neutral molecules used in the AM1,SM2 parameterization, and the polarized continuum method is taken as the standard by which the results are assessed. Regression analysis shows that the method gives a small improvement over the standard Poisson Boltzmann method or a dramatic improvement over the Born method. The system presented here represents one of the more straightforward applications of the multilayered approach to solvation, but other more sophisticated approaches are discussed. © 2004 Wiley Periodicals, Inc. J Comput Chem 25: 627,631, 2004 [source] Biomedical applications of 10B and 11B NMRNMR IN BIOMEDICINE, Issue 2 2005Peter Bendel Abstract This review focuses mainly on the detection and investigation of molecules used for boron neutron capture therapy (BNCT) by 10B and 11B NMR. In this binary radiation treatment, boron-containing molecules (also called ,BNCT agents') enriched in the 10B isotope, are targeted to the tumor, and irradiated with thermal or epithermal neutrons. Capture of these neutrons by 10B nuclei generates cell-damaging radiation, confined to single cell dimensions. NMR research efforts have primarily been applied in two directions: first, to investigate the metabolism and pharmaco-kinetics of BNCT agents in-vivo, and second, to use localized NMR spectroscopy and/or MRI for non-invasive mapping of the administered molecules in treated animals or patients. While the first goal can be pursued using 11B NMR for natural-abundance samples (80% 11B / 20% 10B), molecules used in the actual treatment are >,95% enriched in 10B, and must therefore be detected by 10B NMR. Both 10B (spin 3) and 11B (spin 3/2) are quadrupolar nuclei, and their typical relaxation times, in common BNCT agents in biological environments, are rather short. This poses some technical challenges, particularly for MRI, which will be reviewed, along with possible solutions. The first attempts at 11B NMR and MRI detection of BNCT agents in biological tissue were conducted over a decade ago. Since then, results from 11B MRI in laboratory animals and in humans have been reported, and 11B NMR spectroscopy provided interesting and unique information about the metabolism of some BNCT agents in cultured cells. 10B NMR was applied either ,indirectly' (in double-resonance experiments involving coupled protons), but also by direct 10B MRI in mice. However, no results involving the NMR detection of 10B-enriched compounds in treated patients have been reported yet. Copyright © 2005 John Wiley & Sons, Ltd. [source] Aided Self-Assembly of Porphyrin Nanoaggregates into Ring-Shaped ArchitecturesCHEMISTRY - A EUROPEAN JOURNAL, Issue 4 2004Marga C. Lensen Abstract The formation of micrometer-sized, highly ordered porphyrin rings on surfaces has been investigated. The porphyrin-based nanoarchitectures are formed by deposition from evaporating solutions through a surface dewetting process which can be tuned by variations in the substitution pattern of the molecules used, the coating of the surface and the conditions under which the evaporation takes place. Control over the combined self-assembly and surface dewetting results in nanorings possessing a defined internal architecture. The ordering of the molecules within the rings has been studied by a variety of microscopy techniques (TEM, AFM, fluorescence microscopy) and the exact ordering of the porphyrins within the rings has been quantified. [source] Biological Factors Influencing Production of Xanthones in Aphloia theiformisCHEMISTRY & BIODIVERSITY, Issue 1 2010Pascal Danthu Abstract Xanthones, and more specifically mangiferin, are molecules used in cosmetics for their photoprotective and anti-aging properties. The richness in xanthones of Aphloia theiformis leaves, a common shrub in Madagascar, can reach almost 12% (in relation to dry biomass). Amongst the A. theiformis studied, two major groups of individuals have been determined: those presenting a high proportion of mangiferin (up to 80% of the xanthones) and those presenting a high proportion of polar xanthones (not yet identified). Our study shows that: i) for each subject, the xanthone content remains stable over time (no seasonal variation); ii) the majority of the trees developing in the light belong to the first group (rich in mangiferin), whereas the individuals growing in the undergrowth are richer in polar xanthones; iii) the distribution of the two groups seems not to have any correlation with taxonomy and, moreover, with the known varieties of A. theiformis, although the micrantha variety is richer in mangiferin. Overall, this information indicates that A. theiformis is a reservoir of xanthones and makes it possible to define a framework for its reasoned management. [source] | |||||||||||||