21 research outputs found

    Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition)

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    In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. For example, a key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process versus those that measure fl ux through the autophagy pathway (i.e., the complete process including the amount and rate of cargo sequestered and degraded). In particular, a block in macroautophagy that results in autophagosome accumulation must be differentiated from stimuli that increase autophagic activity, defi ned as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (inmost higher eukaryotes and some protists such as Dictyostelium ) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the fi eld understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. It is worth emphasizing here that lysosomal digestion is a stage of autophagy and evaluating its competence is a crucial part of the evaluation of autophagic flux, or complete autophagy. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. Along these lines, because of the potential for pleiotropic effects due to blocking autophagy through genetic manipulation it is imperative to delete or knock down more than one autophagy-related gene. In addition, some individual Atg proteins, or groups of proteins, are involved in other cellular pathways so not all Atg proteins can be used as a specific marker for an autophagic process. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field

    Aufbau und Realisierung des MeDoc-Volltextspeichers

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    Modeling Multiuser Interactions

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    Due to the growth of the Internet and the fact that more and more people have access to networked computers research on computer supported collaborative learning (CSCL) has gained importance. However development of CSCL environments is expensive. Developers need to consider e.g. distributed computing and team-building and content presentation. Even more difficult is the development of collaborative multimedia teaching/learning software. To reduce development time and costs models and tools are needed that support developers of CSCL applications. This paper describes MoMI, a model for multiuser interactions. With the help of MoMI developers may specify how various users take part in an interaction. The main focus of MoMI is on collaborative interactions in synchronous applications, i.e. interactions where more than one user has to take part in the interaction. MoMI specifies e.g. that an interaction is accepted by the application after all users pressed the same button. Another specification may be that a selection between different films is taken if at least half of the users agree on the same film. There are various other examples for multi-user interactions

    The MeDoc Distributed Electronic Library Accounting and Security Aspects (Extended Abstract)

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    Michael Breu Anne Bruggemann-Klein y Cornelia Haber z Ricarda Weber x November 1, 1996 Abstract The MeDoc service provides access to a distributed full-text library for computer scientists over the internet. Since the library provides commercial information products, accounting and security aspects are of considerable importance in this electronic-publishing project. MeDoc has developed business, cost, and payment models suitable for an electronic library service. Communication channels are secured by transparent encryption mechanisms based on SSL. These mechanisms are implemented in a prototype that will be evaluated in a first field test starting at the end of 1996. 1 Introduction The MeDoc 1 service provides a distributed electronic full-text library of high quality computer-science literature. This library can only be furnished with commercial products, if usage is billable and protected. Therefore flexible business, cost and payment models and user-transparent ways to s..

    The MeDoc Distributed Electronic Library Accounting and Security Aspects

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    The MeDoc service provides access to a distributed full-text library for computer scientists over the Internet. Since the library provides commercial information products, accounting and security aspects are of considerable importance in this electronic-publishing project. MeDoc has developed business, cost, and payment models suitable for electronic library services. The partners cooperating in the MeDoc service are users, providers and producers of information products. Their business interaction is based on trade as opposed to systems financed by advertising. The cost models offered to the users are various forms of subscription and "pay per view"-purchase. As payment models both credit and debit models are considered suitable for the MeDoc service. Initially only registered users are admitted to the MeDoc library, so the users can be charged via accounts. Currently a clearing agency handles the actual invoice process for the MeDoc service. To secure the communication over the Inter..

    Silica–Conjugated Polymer Hybrid Fluorescent Nanoparticles: Preparation by Surface-Initiated Polymerization and Spectroscopic Studies

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    Organic/inorganic hybrid nanoscale materials possess fascinating optical, electronic, magnetic, and catalytic properties that are promising for a variety of practical applications. Such properties can be dramatically affected by the hierarchical structure and molecular organization in the nanomaterials. Herein, we employed surface-initiated Kumada catalyst-transfer polymerization to prepare hybrid materials consisting of shells of conjugated polymers (CPs)polythiophene or poly­(<i>p</i>-phenylene)and their block copolymers covalently attached to the surface of silica nanoparticles. Because of the controlled chain-growth mechanism of surface-initiated polymerization, we obtained structurally well-defined CP blocks in the diblock copolymer shells, which produced distinct spectroscopic properties related to the intraparticle excitation energy transfer between the nanoscale polymer shell components, as well as the formation of interfacial exciplex states. The spectroscopic phenomena were further understood via time-resolved transient absorption spectroscopy studies. Overall, the surface-initiated polymerization provided an efficient tool to prepare structurally defined and highly stable organic polymer shell–inorganic core nanoparticles with tunable spectroscopic characteristics not achievable from corresponding single-component systems
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