Protective Effects of a Hyaluronan-Binding Peptide (P15-1) on Mesenchymal Stem Cells in an Inflammatory Environment

Mesenchymal stem cells (MSCs) obtained from various sources, including bone marrow, have been proposed as a therapeutic strategy for the improvement of tissue repair/regeneration, including the repair of cartilage defects or lesions. Often the highly inflammatory environment after injury or during diseases, however, greatly diminishes the therapeutic and reparative effectiveness of MSCs. Therefore, the identification of novel factors that can protect MSCs against an inflammatory environment may enhance the effectiveness of these cells in repairing tissues, such as articular cartilage. In this study, we investigated whether a peptide (P15-1) that binds to hyaluronan (HA), a major component of the extracellular matrix of cartilage, protects bone-marrow-derived MSCs (BMSCs) in an inflammatory environment. The results showed that P15-1 reduced the mRNA levels of catabolic and inflammatory markers in interleukin-1beta (IL-1β)-treated human BMSCs. In addition, P15-1 enhanced the attachment of BMSCs to HA-coated tissue culture dishes and stimulated the chondrogenic differentiation of the multipotential murine C3H/10T1/2 MSC line in a micromass culture. In conclusion, our findings suggest that P15-1 may increase the capacity of BMSCs to repair cartilage via the protection of these cells in an inflammatory environment and the stimulation of their attachment to an HA-containing matrix and chondrogenic differentiation.     

Nanovesicles Based on Mixtures of a Biantennary Glycolipid with Ionic Co‐Surfactants

A biantennary surfactant based on a synthetic C₁₆‐maltoside was chosen to prepare vesicles for a potential vesicular drug delivery system. The synthesis comprised of three stages: Initial synthesis of β‐d ‐maltose octaacetate was followed by glycosidation of 2‐hexyl‐decanol and final glycolipid deacetylation. Both α‐ and β‐anomers were prepared and their anomeric purity was evaluated by ¹H NMR. Owing to the low water solubility of the glycolipid, addition of ionic co‐surfactants was believed to promote the surfactant distribution, thus leading to smaller and more uniform vesicles. The assembly behavior of the surfactant systems was studied by contact penetration under an optical polarizing microscope, while interfacial properties were determined by surface tension measurements. Vesicles were prepared by injection of an ethanolic solution into bulk water and investigated by dynamic light scattering and field emission scanning electron microscopy. Contact of the surfactant mixtures with water indicated a high tendency to exhibit the lamellar phase and confirmed the expected low molecular solubility. These findings suggest a potential of the surfactant to form stable vesicles. Injection of an ethanolic surfactant solution into bulk water gave sub‐micrometer sized vesicles with a narrow size distribution. Application of ionic co‐surfactants reduced the vesicle size. In particular ～20 % of anionic SDS proved highly effective, lowering the vesicle size by nearly one decade, thus accessing nano‐sized vesicles. Encapsulation of a water‐soluble drug was achieved in a 76 ± 10 % efficiency.     

IV-Controlling in einem Systemhaus

This paper analyses the characteristics of software houses as service providers. The tasks of internal IT-services are determined from these characteristics and a reporting system for the IT-controlling is outlined. The concept results from the analysis of one of the 25 largest German software houses. The paper concludes with a case study of the fiscal year 2000 IT-controlling report of the above-mentioned firm.     

Sicherung der Netzneutralität

Die Geschichte des Internets ist eine Erfolgsgeschichte. Dieser Erfolg beruht u.a. auf einer neutralen Datenübermittlung, die dadurch gekennzeichnet ist, dass Netzbetreiber Datenpakete von und an ihre Kunden unver?ndert und gleichberechtigt übertragen, unabh?ngig davon, woher diese stammen und welche Anwendungen die Pakete generiert haben. In jüngster Zeit werden Forderungen nach Verkehrsregelungen im Internet lauter. Begründet wird diese Initiative mit einer drohenden Netzüberlastung, die durch die wachsende Popularit?t von Videoangeboten wie YouTube oder Streaming-Angeboten wie Hulu entsteht. Kritiker befürchten, dass durch den Einsatz neuer Netzwerkmanagementtechniken die Innovationsoffenheit und die freie Kommunikation im Internet gef?hrdet werden. Der Beitrag analysiert die M?glichkeiten und Grenzen der Gew?hrleistung von Netzneutralit?t durch das deutsche Telekommunikations- und Medienrecht.     

Computational aspects of prospect theory with asset pricing applications

We develop an algorithm to compute asset allocations for Kahneman and Tversky’s (Econometrica, 47(2), 263–291, 1979) prospect theory. An application to benchmark data as in Fama and French (Journal of Financial Economics, 47(2), 427–465, 1992) shows that the equity premium puzzle is resolved for parameter values similar to those found in the laboratory experiments of Kahneman and Tversky (Econometrica, 47(2), 263–291, 1979). While previous studies like Benartzi and Thaler (The Quarterly Journal of Economics, 110(1), 73–92, 1995), Barberis, Huang and Santos (The Quarterly Journal of Economics, 116(1), 1–53, 2001), and Grüne and Semmler (Asset prices and loss aversion, Germany, Mimeo Bielefeld University, 2005) focussed on dynamic aspects of asset pricing but only used loss aversion to explain the equity premium puzzle our paper explains the unconditional moments of asset pricing by a static two-period optimization problem. However, we incorporate asymmetric risk aversion. Our approach allows reducing the degree of loss aversion from 2.353 to 2.25, which is the value found by Tversky and Kahneman (Journal of Risk and Uncertainty, 5, 297–323, 1992) while increasing the risk aversion from 1 to 0.894, which is a slightly higher value than the 0.88 found by Tversky and Kahneman (Journal of Risk and Uncertainty, 5, 297–323, 1992). The equivalence of these parameter settings is robust to incorporating the size and the value portfolios of Fama and French (Journal of Finance, 47(2), 427–465, 1992). However, the optimal prospect theory portfolios found on this larger set of assets differ drastically from the optimal mean-variance portfolio.     

Optimization of a parallel permutation testing function for the SPRINT R package

The statistical language R and its Bioconductor package are favoured by many biostatisticians for processing microarray data. The amount of data produced by some analyses has reached the limits of many common bioinformatics computing infrastructures. High Performance Computing systems offer a solution to this issue. The Simple Parallel R Interface (SPRINT) is a package that provides biostatisticians with easy access to High Performance Computing systems and allows the addition of parallelized functions to R. Previous work has established that the SPRINT implementation of an R permutation testing function has close to optimal scaling on up to 512 processors on a supercomputer. Access to supercomputers, however, is not always possible, and so the work presented here compares the performance of the SPRINT implementation on a supercomputer with benchmarks on a range of platforms including cloud resources and a common desktop machine with multiprocessing capabilities. Copyright © 2011 John Wiley & Sons, Ltd.     

Control reconfiguration after actuator failures by Markov parameter matching

Two novel linear control reconfiguration methods for plants subject to actuator failures are described. The common idea is to place a reconfiguration block between the faulty plant and the nominal controller in order to re-route the signals around the broken actuator. The first method uses a computationally simple static reconfiguration block. It recovers the nominal plant input/output-behaviour by assigning the faulty plant the same Markov parameters as the faultless plant. The second method concerns the design of the feedforward part in the virtual actuator using the idea and results of the first approach. The virtual actuator is a dynamical reconfiguration block. Existence conditions and solution algorithms are provided, and it is shown that both approaches guarantee the closed-loop stability if the existence conditions are met. An experimental study demonstrates the practical usability of the proposed approaches.