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971.
The reactions of DL-1,4-disulfanylbutane-2,3-diol and 1,3-disulfanylpropan-2-ol with dodecacarbonyltriiron have been investigated. As main products, the iron complexes 1 and 2 were isolated and characterized by spectroscopic methods, as well as single crystal X-ray analysis. Additionally, the unusually large bond angles in the dithiolato bridge was investigated via density-functional theory (DFT) calculations. Moreover, the electrochemical features have been studied by cyclic voltammetry. 相似文献
972.
Mueller LN Rinner O Schmidt A Letarte S Bodenmiller B Brusniak MY Vitek O Aebersold R Müller M 《Proteomics》2007,7(19):3470-3480
Label-free quantification of high mass resolution LC-MS data has emerged as a promising technology for proteome analysis. Computational methods are required for the accurate extraction of peptide signals from LC-MS data and the tracking of these features across the measurements of different samples. We present here an open source software tool, SuperHirn, that comprises a set of modules to process LC-MS data acquired on a high resolution mass spectrometer. The program includes newly developed functionalities to analyze LC-MS data such as feature extraction and quantification, LC-MS similarity analysis, LC-MS alignment of multiple datasets, and intensity normalization. These program routines extract profiles of measured features and comprise tools for clustering and classification analysis of the profiles. SuperHirn was applied in an MS1-based profiling approach to a benchmark LC-MS dataset of complex protein mixtures with defined concentration changes. We show that the program automatically detects profiling trends in an unsupervised manner and is able to associate proteins to their correct theoretical dilution profile. 相似文献
973.
Stripe assays have been widely employed as in vitro test systems to study the responses of growing axons, as well as migrating cells, to established or novel guidance molecules. We provide detailed protocols for both the original and the modified version of this assay, as they allow the analysis of the 'guidance properties' of active components present in crude membrane fractions or as purified molecules. Silicon matrices are used to produce striped patterns of active molecules on a surface (referred to as 'carpet'), followed by culturing of neurons, or any other cell type, on these carpets. After 1-2 days in culture, striped outgrowth of extending neurites--indicative of guided migration of cell processes--can be observed. We also discuss potential other applications (e.g., in neuronal regeneration and development) and modifications of the assay. The preparation of 10-12 carpets takes approximately 4-5 h. 相似文献
974.
From traditional Chinese medicine to rational cancer therapy 总被引:3,自引:0,他引:3
Many natural products and derivatives thereof belong to the standard repertoire of cancer chemotherapy. Examples are Vinca alkaloids, taxanes and camptothecins. In recent years, the potential of natural products from plants, notably from medicinal plants used in traditional Chinese medicine (TCM), has been recognized by the scientific community in the Western world. To provide an example of the most recent developments in this field, we have selected several compounds, namely artesunate, homoharringtonine, arsenic trioxide and cantharidin, that are found in natural TCM products and that have the potential for use in cancer therapy. Controlled clinical studies have shown that homoharringtonine and arsenic trioxide can exert profound activity against leukaemia. Increased knowledge of the molecular mechanisms of TCM-derived drugs and recent developments in their applications demonstrate that the combination of TCM with modern cutting-edge technologies provides an attractive strategy for the development of novel and improved cancer therapeutics. 相似文献
975.
Background
Fluorescence activated cell sorting (FACS) is a powerful technique for the qualitative and quantitative detection of biomolecules used widely in both basic research and clinical diagnostic applications. Beads displaying a specific antigen are used to bind antibodies which are then fluorescently labelled using secondary antibodies. As the individual suspension bead passes through the sensing region of the FACS machine, fluorescent signals are acquired and analysed. Currently, antigens are tediously purified and chemically cross-linked to preformed beads. Purification and coupling of proteins often renders them inactive and they will not be displayed in its native configuration. As an alternative, we genetically engineered Escherichia coli to produce biopolyester (polyhdroxyalkanoate=PHA) granules displaying diagnostically relevant antigens in their native conformation and suitable for FACS analysis. 相似文献976.
Lepenies B Gaworski I Tartz S Langhorne J Fleischer B Jacobs T 《Microbes and infection / Institut Pasteur》2007,9(6):687-694
An immune response against malaria has to be tightly controlled. The production of pro-inflammatory cytokines is required to control parasites but the same cytokines are also involved in severe malaria. We have shown that CTLA-4 expression during Plasmodium berghei malaria dampens the immune response. This strain provokes a pro-inflammatory immune response that is associated with the pathology of cerebral malaria. Accordingly a blockade of CTLA-4 during the blood-stage of P. berghei malaria leads to an exacerbation of disease. To analyze the effects of a CTLA-4 blockade in a malaria model which is not prone to immune pathology we employed P. yoelii infection. Blood-stage infection led to a rapid induction of CTLA-4 on T cells. Using the non-lethal P. yoelii strain Py17NL we found that a blockade of CTLA-4 resulted in an increased T cell activation and IFN-gamma production, which was accompanied by a lower peak parasitemia and earlier parasite clearance. In contrast, blockade of CTLA-4 during infection with a P. yoelii strain exhibiting a higher parasitemia induced markedly increased serum-levels of TNF-alpha, which was associated with severe inflammation and reduced survival. 相似文献
977.
Transgenic mice are an effective model to study gene function in vivo; however, position effects can complicate tissue-specific transgene analysis. To facilitate precise targeting of a transgenic construct into the mouse genome, we combined the Cre/lox and Flp/FRT recombination systems to allow for rapid transgene replacement and conditional transgene expression from the endogenous beta-actin locus. Flp/FRT recombination was used to rapidly exchange FRT-flanked transgene cassettes by recombinase-mediated cassette exchange in embryonic stem cells, while transgene expression can be activated in mice after Cre-mediated excision of a floxed STOP cassette. To validate our system, we analyzed the expression profile of an EGFP reporter gene after integration into the beta-actin locus and Cre-mediated excision of the floxed STOP cassette. Breeding of EGFP reporter mice with various Cre mouse lines resulted in the expected expression profiles, demonstrating the feasibility of the model to facilitate predictable and strong transgene expression in a spatially and temporally controlled manner. 相似文献
978.
Gu S Anderson I Kunin V Cipriano M Minovitsky S Weber G Amenta N Hamann B Dubchak I 《Bioinformatics (Oxford, England)》2007,23(6):764-766
We describe a general multiplatform exploratory tool called TreeQ-Vista, designed for presenting functional annotations in a phylogenetic context. Traits, such as phenotypic and genomic properties, are interactively queried from a user-provided relational database with a user-friendly interface which provides a set of tools for users with or without SQL knowledge. The query results are projected onto a phylogenetic tree and can be displayed in multiple color groups. A rich set of browsing, grouping and query tools are provided to facilitate trait exploration, comparison and analysis. AVAILABILITY: The program, detailed tutorial and examples are available online (http:/genome.lbl.gov/vista/TreeQVista). 相似文献
979.
PepSplice: cache-efficient search algorithms for comprehensive identification of tandem mass spectra
Roos FF Jacob R Grossmann J Fischer B Buhmann JM Gruissem W Baginsky S Widmayer P 《Bioinformatics (Oxford, England)》2007,23(22):3016-3023
MOTIVATION: Tandem mass spectrometry allows for high-throughput identification of complex protein samples. Searching tandem mass spectra against sequence databases is the main analysis method nowadays. Since many peptide variations are possible, including them in the search space seems only logical. However, the search space usually grows exponentially with the number of independent variations and may therefore overwhelm computational resources. RESULTS: We provide fast, cache-efficient search algorithms to screen large peptide search spaces including non-tryptic peptides, whole genomes, dozens of posttranslational modifications, unannotated point mutations and even unannotated splice sites. All these search spaces can be screened simultaneously. By optimizing the cache usage, we achieve a calculation speed that closely approaches the limits of the hardware. At the same time, we control the size of the overall search space by limiting the combinations of variations that can co-occur on the same peptide. Using a hypergeometric scoring scheme, we applied these algorithms to a dataset of 1 420 632 spectra. We were able to identify a considerable number of peptide variations within a modest amount of computing time on standard desktop computers. 相似文献
980.
Rahel Decker Christoph Burdelski Melanie Zobiak Henning Büttner Gefion Franke Martin Christner Katharina Sa? Bernd Zobiak Hanae A. Henke Alexander R. Horswill Markus Bischoff Stephanie Bur Torsten Hartmann Carolyn R. Schaeffer Paul D. Fey Holger Rohde 《PLoS pathogens》2015,11(3)
Virulence of the nosocomial pathogen Staphylococcus epidermidis is crucially linked to formation of adherent biofilms on artificial surfaces. Biofilm assembly is significantly fostered by production of a bacteria derived extracellular matrix. However, the matrix composition, spatial organization, and relevance of specific molecular interactions for integration of bacterial cells into the multilayered biofilm community are not fully understood. Here we report on the function of novel 18 kDa Small basic protein (Sbp) that was isolated from S. epidermidis biofilm matrix preparations by an affinity chromatographic approach. Sbp accumulates within the biofilm matrix, being preferentially deposited at the biofilm–substratum interface. Analysis of Sbp-negative S. epidermidis mutants demonstrated the importance of Sbp for sustained colonization of abiotic surfaces, but also epithelial cells. In addition, Sbp promotes assembly of S. epidermidis cell aggregates and establishment of multilayered biofilms by influencing polysaccharide intercellular-adhesin (PIA) and accumulation associated protein (Aap) mediated intercellular aggregation. While inactivation of Sbp indirectly resulted in reduced PIA-synthesis and biofilm formation, Sbp serves as an essential ligand during Aap domain-B mediated biofilm accumulation. Our data support the conclusion that Sbp serves as an S. epidermidis biofilm scaffold protein that significantly contributes to key steps of surface colonization. Sbp-negative S. epidermidis mutants showed no attenuated virulence in a mouse catheter infection model. Nevertheless, the high prevalence of sbp in commensal and invasive S. epidermidis populations suggests that Sbp plays a significant role as a co-factor during both multi-factorial commensal colonization and infection of artificial surfaces. 相似文献