288 research outputs found

    Domain Growth Kinetics in a Cell-sized Liposome

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    We investigated the kinetics of domain growth on liposomes consisting of a ternary mixture (unsaturated phospholipid, saturated phospholipid, and cholesterol) by temperature jump. The domain growth process was monitored by fluorescence microscopy, where the growth was mediated by the fusion of domains through the collision. It was found that an average domain size r develops with time t as r ~ t^0.15, indicating that the power is around a half of the theoretical expectation deduced from a model of Brownian motion on a 2-dimensional membrane. We discuss the mechanism of the experimental scaling behavior by considering the elasticity of the membrane

    Calorimetric Behavior of Phosphatidylcholine/Phosphatidylethanolamine Bilayers is Compatible with the Superlattice Model

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    Differential scanning calorimetry was used to study the phase behavior of binary lipid bilayers consisting of phosphatidylcholine (PC) and phosphatidylethanolamine (PE) of varying acyl chain length. A two-state transition model was used to resolve the individual transition components, and the two-state transition enthalpy, the relative enthalpy, and the transition temperature of each component were plotted as a function of composition. Intriguingly, abrupt changes in these thermodynamic parameters were observed at or close to many “critical” XPE values predicted by the superlattice model proposing that phospholipids with different headgroups tend to adopt regular rather than random lateral distributions. Statistical analysis indicated that the agreement between the observed and predicted “critical” compositions is highly significant. Accordingly, these data provide strong evidence that the molecules in PC/PE bilayers tend to adopt regular, superlattice-like lateral arrangements, which could be involved in the regulation of the lipid compositions of biological membranes

    An enterprise engineering approach for the alignment of business and information technology strategy

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    Information systems and information technology (IS/IT, hereafter just IT) strategies usually depend on a business strategy. The alignment of both strategies improves their strategic plans. From an external perspective, business and IT alignment is the extent to which the IT strategy enables and drives the business strategy. This article reviews strategic alignment between business and IT, and proposes the use of enterprise engineering (EE) to achieve this alignment. The EE approach facilitates the definition of a formal dialog in the alignment design. In relation to this, new building blocks and life-cycle phases have been defined for their use in an enterprise architecture context. This proposal has been adopted in a critical process of a ceramic tile company for the purpose of aligning a strategic business plan and IT strategy, which are essential to support this process. © 2011 Taylor & Francis.Cuenca, L.; Boza, A.; Ortiz, A. (2011). An enterprise engineering approach for the alignment of business and information technology strategy. International Journal of Computer Integrated Manufacturing. 24(11):974-992. https://doi.org/10.1080/0951192X.2011.579172S9749922411(1993). CIMOSA: Open System Architecture for CIM. doi:10.1007/978-3-642-58064-2Ang, J., Shaw, N., & Pavri, F. (1995). Identifying strategic management information systems planning parameters using case studies. International Journal of Information Management, 15(6), 463-474. doi:10.1016/0268-4012(95)00049-dAvison, D., Jones, J., Powell, P., & Wilson, D. (2004). Using and validating the strategic alignment model. The Journal of Strategic Information Systems, 13(3), 223-246. doi:10.1016/j.jsis.2004.08.002Avgerou, & McGrath. (2007). Power, Rationality, and the Art of Living through Socio-Technical Change. MIS Quarterly, 31(2), 295. doi:10.2307/25148792Bergeron, F., Raymond, L., & Rivard, S. (2004). Ideal patterns of strategic alignment and business performance. Information & Management, 41(8), 1003-1020. doi:10.1016/j.im.2003.10.004Bernus, P., Nemes, L., & Schmidt, G. (Eds.). (2003). Handbook on Enterprise Architecture. doi:10.1007/978-3-540-24744-9Bleistein, S. J., Cox, K., Verner, J., & Phalp, K. T. (2006). B-SCP: A requirements analysis framework for validating strategic alignment of organizational IT based on strategy, context, and process. Information and Software Technology, 48(9), 846-868. doi:10.1016/j.infsof.2005.12.001Buchanan, S., & Gibb, F. (1998). The information audit: An integrated strategic approach. International Journal of Information Management, 18(1), 29-47. doi:10.1016/s0268-4012(97)00038-8Buchanan, S., & Gibb, F. (2007). The information audit: Role and scope. International Journal of Information Management, 27(3), 159-172. doi:10.1016/j.ijinfomgt.2007.01.002Chen, D., & Vernadat, F. (2004). Standards on enterprise integration and engineering—state of the art. International Journal of Computer Integrated Manufacturing, 17(3), 235-253. doi:10.1080/09511920310001607087Chen, D., Doumeingts, G., & Vernadat, F. (2008). Architectures for enterprise integration and interoperability: Past, present and future. Computers in Industry, 59(7), 647-659. doi:10.1016/j.compind.2007.12.016Chen, H.-M., Kazman, R., & Garg, A. (2005). BITAM: An engineering-principled method for managing misalignments between business and IT architectures. Science of Computer Programming, 57(1), 5-26. doi:10.1016/j.scico.2004.10.002Cuenca, L., Ortiz, A., & Vernadat, F. (2006). From UML or DFD models to CIMOSA partial models and enterprise components. International Journal of Computer Integrated Manufacturing, 19(3), 248-263. doi:10.1080/03081070500065841Davis, G. B. (2000). Information Systems Conceptual Foundations: Looking Backward and Forward. IFIP Advances in Information and Communication Technology, 61-82. doi:10.1007/978-0-387-35505-4_5Gindy, N., Morcos, M., Cerit, B., & Hodgson, A. (2008). Strategic technology alignment roadmapping STAR® aligning R&D investments with business needs. International Journal of Computer Integrated Manufacturing, 21(8), 957-970. doi:10.1080/09511920801927148Goethals, F. G., Lemahieu, W., Snoeck, M., & Vandenbulcke, J. A. (2007). The data building blocks of the enterprise architect. Future Generation Computer Systems, 23(2), 269-274. doi:10.1016/j.future.2006.05.004Greefhorst, D., Koning, H., & Vliet, H. van. (2006). The many faces of architectural descriptions. Information Systems Frontiers, 8(2), 103-113. doi:10.1007/s10796-006-7975-xGregor, S., Hart, D., & Martin, N. (2007). Enterprise architectures: enablers of business strategy and IS/IT alignment in government. Information Technology & People, 20(2), 96-120. doi:10.1108/09593840710758031Hartono, E., Lederer, A. L., Sethi, V., & Zhuang, Y. (2003). Key predictors of the implementation of strategic information systems plans. ACM SIGMIS Database, 34(3), 41-53. doi:10.1145/937742.937747Henderson, J. C., & Venkatraman, H. (1993). Strategic alignment: Leveraging information technology for transforming organizations. IBM Systems Journal, 32(1), 472-484. doi:10.1147/sj.382.0472Hirschheim, R., & Sabherwal, R. (2001). Detours in the Path toward Strategic Information Systems Alignment. California Management Review, 44(1), 87-108. doi:10.2307/41166112Hoogervorst, J. A. P. (2009). Enterprise Governance and Enterprise Engineering. doi:10.1007/978-3-540-92671-9Johnson, A. M., & Lederer, A. L. (2010). CEO/CIO mutual understanding, strategic alignment, and the contribution of IS to the organization. Information & Management, 47(3), 138-149. doi:10.1016/j.im.2010.01.002JONKERS, H., LANKHORST, M., VAN BUUREN, R., HOPPENBROUWERS, S., BONSANGUE, M., & VAN DER TORRE, L. (2004). CONCEPTS FOR MODELING ENTERPRISE ARCHITECTURES. International Journal of Cooperative Information Systems, 13(03), 257-287. doi:10.1142/s0218843004000985King, W. R. (1978). Strategic Planning for Management Information Systems. MIS Quarterly, 2(1), 27. doi:10.2307/249104Leonard, J. (2007). Sharing a Vision: comparing business and IS managers’ perceptions of strategic alignment issues. Australasian Journal of Information Systems, 15(1). doi:10.3127/ajis.v15i1.299Luftman, J. N., Lewis, P. R., & Oldach, S. H. (1993). Transforming the enterprise: The alignment of business and information technology strategies. IBM Systems Journal, 32(1), 198-221. doi:10.1147/sj.321.0198Luftman, J., Ben-Zvi, T., Dwivedi, R., & Rigoni, E. H. (2010). IT Governance. International Journal of IT/Business Alignment and Governance, 1(2), 13-25. doi:10.4018/jitbag.2010040102Melville, Kraemer, & Gurbaxani. (2004). Review: Information Technology and Organizational Performance: An Integrative Model of IT Business Value. MIS Quarterly, 28(2), 283. doi:10.2307/25148636Newkirk, H. E., & Lederer, A. L. (2006). Incremental and Comprehensive Strategic Information Systems Planning in an Uncertain Environment. IEEE Transactions on Engineering Management, 53(3), 380-394. doi:10.1109/tem.2006.877446Noran, O. (2003). An analysis of the Zachman framework for enterprise architecture from the GERAM perspective. Annual Reviews in Control, 27(2), 163-183. doi:10.1016/j.arcontrol.2003.09.002Noran, O. (2005). A systematic evaluation of the C4ISR AF using ISO15704 Annex A (GERAM). Computers in Industry, 56(5), 407-427. doi:10.1016/j.compind.2004.12.005Ortiz, A., Lario, F., & Ros, L. (1999). Enterprise Integration—Business Processes Integrated Management: a proposal for a methodology to develop Enterprise Integration Programs. Computers in Industry, 40(2-3), 155-171. doi:10.1016/s0166-3615(99)00021-4Panetto, H., Baïna, S., & Morel, G. (2007). Mapping the IEC 62264 models onto the Zachman framework for analysing products information traceability: a case study. Journal of Intelligent Manufacturing, 18(6), 679-698. doi:10.1007/s10845-007-0040-xPapp, R. (Ed.). (2001). Strategic Information Technology. doi:10.4018/978-1-87828-987-2Peñaranda, N., Mejía, R., Romero, D., & Molina, A. (2010). Implementation of product lifecycle management tools using enterprise integration engineering and action-research. International Journal of Computer Integrated Manufacturing, 23(10), 853-875. doi:10.1080/0951192x.2010.495136Reich, B. H., & Benbasat, I. (2000). Factors That Influence the Social Dimension of Alignment between Business and Information Technology Objectives. MIS Quarterly, 24(1), 81. doi:10.2307/3250980Sledgianowski, D., & Luftman, J. (2005). IT-Business Strategic Alignment Maturity. Journal of Cases on Information Technology, 7(2), 102-120. doi:10.4018/jcit.2005040107Sowa, J. F., & Zachman, J. A. (1992). Extending and formalizing the framework for information systems architecture. IBM Systems Journal, 31(3), 590-616. doi:10.1147/sj.313.0590Van Grembergen, W., & De Haes, S. (2010). A Research Journey into Enterprise Governance of IT, Business/IT Alignment and Value Creation. International Journal of IT/Business Alignment and Governance, 1(1), 1-13. doi:10.4018/jitbag.2010120401Xueying Wang, Xiongwei Zhou, & Longbin Jiang. (2008). A method of business and IT alignment based on Enterprise Architecture. 2008 IEEE International Conference on Service Operations and Logistics, and Informatics. doi:10.1109/soli.2008.468649

    Sheddable Coatings for Long-Circulating Nanoparticles

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    Nanoparticles, such as liposomes, polymeric micelles, lipoplexes and polyplexes are frequently studied as targeted drug carrier systems. The ability of these particles to circulate in the bloodstream for a prolonged period of time is often a prerequisite for successful targeted delivery. To achieve this, hydrophilic ‘stealth’ polymers, such as poly(ethylene glycol) (PEG), are used as coating materials. Such polymers shield the particle surface and thereby reduce opsonization by blood proteins and uptake by macrophages of the mononuclear phagocyte system. Yet, after localizing in the pathological site, nanoparticles should deliver their contents in an efficient manner to achieve a sufficient therapeutic response. The polymer coating, however, may hinder drug release and target cell interaction and can therefore be an obstacle in the realization of the therapeutic response. Attempts have been made to enhance the therapeutic efficacy of sterically stabilized nanoparticles by means of shedding, i.e. a loss of the coating after arrival at the target site. Such an ‘unmasking’ process may facilitate drug release and/or target cell interaction processes. This review presents an overview of the literature regarding different shedding strategies that have been investigated for the preparation of sterically stabilized nanoparticulates. Detach mechanisms and stimuli that have been used are described

    Bordetella Adenylate Cyclase Toxin Mobilizes Its β2 Integrin Receptor into Lipid Rafts to Accomplish Translocation across Target Cell Membrane in Two Steps

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    Bordetella adenylate cyclase toxin (CyaA) binds the αMβ2 integrin (CD11b/CD18, Mac-1, or CR3) of myeloid phagocytes and delivers into their cytosol an adenylate cyclase (AC) enzyme that converts ATP into the key signaling molecule cAMP. We show that penetration of the AC domain across cell membrane proceeds in two steps. It starts by membrane insertion of a toxin ‘translocation intermediate’, which can be ‘locked’ in the membrane by the 3D1 antibody blocking AC domain translocation. Insertion of the ‘intermediate’ permeabilizes cells for influx of extracellular calcium ions and thus activates calpain-mediated cleavage of the talin tether. Recruitment of the integrin-CyaA complex into lipid rafts follows and the cholesterol-rich lipid environment promotes translocation of the AC domain across cell membrane. AC translocation into cells was inhibited upon raft disruption by cholesterol depletion, or when CyaA mobilization into rafts was blocked by inhibition of talin processing. Furthermore, CyaA mutants unable to mobilize calcium into cells failed to relocate into lipid rafts, and failed to translocate the AC domain across cell membrane, unless rescued by Ca2+ influx promoted in trans by ionomycin or another CyaA protein. Hence, by mobilizing calcium ions into phagocytes, the ‘translocation intermediate’ promotes toxin piggybacking on integrin into lipid rafts and enables AC enzyme delivery into host cytosol

    Electron spin resonance in membrane research: protein–lipid interactions from challenging beginnings to state of the art

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    Conventional electron paramagnetic resonance (EPR) spectra of lipids that are spin-labelled close to the terminal methyl end of the acyl chains are able to resolve the lipids directly contacting the protein from those in the fluid bilayer regions of the membrane. This allows determination of both the stoichiometry of lipid–protein interaction (i.e., number of lipid sites at the protein perimeter) and the selectivity of the protein for different lipid species (i.e., association constants relative to the background lipid). Spin-label EPR data are summarised for 20 or more different transmembrane peptides and proteins, and 7 distinct species of lipids. Lineshape simulations of the two-component conventional spin-label EPR spectra allow estimation of the rate at which protein-associated lipids exchange with those in the bulk fluid regions of the membrane. For lipids that do not display a selectivity for the protein, the intrinsic off-rates for exchange are in the region of 10 MHz: less than 10× slower than the rates of diffusive exchange in fluid lipid membranes. Lipids with an affinity for the protein, relative to the background lipid, have off-rates for leaving the protein that are correspondingly slower. Non-linear EPR, which depends on saturation of the spectrum at high radiation intensities, is optimally sensitive to dynamics on the timescale of spin-lattice relaxation, i.e., the microsecond regime. Both progressive saturation and saturation transfer EPR experiments provide definitive evidence that lipids at the protein interface are exchanging on this timescale. The sensitivity of non-linear EPR to low frequencies of spin exchange also allows the location of spin-labelled membrane protein residues relative to those of spin-labelled lipids, in double-labelling experiments

    Factors Underlying Technology Adoption in Academic Libraries in Kuwait

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    The study analysed factors shaping adoption of technology in academic libraries in Kuwait. The research was based on interviews conducted with library directors, staff and users, combined with observation and document analysis. A major aspect of the Kuwaiti context was a relative lack of financial restraints and an enthusiasm for technology within society as a whole. Other important influences shaping technology adoption specifically within libraries were the top down decision making style and a quest for prestige, in a context of a lack of library culture among users, shortage of professional staff and a strong, perhaps exaggerated, faith in technology as a solution to problems
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