Culture and its perception in strategic alliances : does it affect the performance? : an exploratory study into Dutch-German ventures

This exploratory study researches the fit of 6 National Culture (NC) and 6 Corporate Culture (CC) parameters in 12 Dutch-German cooperations. 24 firms were asked to verify the nature of their cultural fit and relating this perception to the perceived alliance performance. There appeared to be a strong (not necessary causal) relationship between the perception of cultural fit and the corresponding alliance performance This finding may have important implications for alliance management. Instead of its general preoccupation with strategic and operational fit among alliance partners, more attention should be paid to cultural fit. The inclusion of cultural fit indicators in the overall partner selection process might well pay off in terms of increased alliance performance

Mesenchymal stem cell fate : applying biomaterials for control of stem cell behavior

The materials pipeline for biomaterials and tissue engineering applications is under continuous development. Specifically, there is great interest in the use of designed materials in the stem cell arena as materials can be used to manipulate the cells providing control of behaviour. This is important as the ability to 'engineer' complexity and subsequent in vitro growth of tissues and organs is a key objective for tissue engineers. This review will describe the nature of the materials strategies, both static and dynamic, and their influence specifically on mesenchymal stem cell fate

Supramolecular fibers in gels can be at thermodynamic equilibrium : a simple packing model reveals preferential fibril formation versus crystallization

Low molecular weight gelators are able to form nanostructures, typically fibers, which entangle to form gel-phase materials. These materials have wide-ranging applications in biomedicine and nanotechnology. While it is known that supramolecular gels often represent metastable structures due to the restricted molecular dynamics in the gel state, the thermodynamic nature of the nanofibrous structure is not well understood. Clearly, 3D extended structures will be able to form more interactions than 1D structures. However, self-assembling molecules are typically amphiphilic, thus giving rise to a combination of solvophobic and solvophilic moieties where a level of solvent exposure at the nanostructure surface is favorable. In this study, we introduce a simple packing model, based on prisms with faces of different nature (solvophobic and solvophilic) and variable interaction parameters, to represent amphiphile self-assembly. This model demonstrates that by tuning shape and "self" or "solvent" interaction parameters either the 1D fiber or 3D crystal may represent the thermodynamic minimum. The model depends on parameters that relate to features of experimentally known systems: The number of faces exposed to the solvent or buried in the fiber; the overall shape of the prism; and the free energy penalties associated with the interactions can be adjusted to match their chemical nature. The model is applied to describe the pH-dependent gelation/precipitation of well-known gelator Fmoc-FF. We conclude that, despite the fact that most experimentally produced gels probably represent metastable states, one-dimensional fibers can represent thermodynamic equilibrium. This conclusion has critical implications for the theoretical treatment of gels

Tripeptide emulsifiers

Traditional, surfactant based emulsions have applications in the food, cosmetic, encapsulation and materials industries. The majority of the surfactants that are currently in use are based on lipids that are extracted from natural sources, however, other surfactants, based on polypeptides, copolymers and solid particles (Pickering emulsions)are also used. The process by which traditional amphiphilic surfactants stabilize biphasic mixtures by interfacial assembly and the consequent reduction of surface tension is well understood. Although these surfactants are well-suited to stabilize emulsions, they are not always biocompatible or biodegradable. In addition, they may not have sufficient stability at elevated temperatures or extremes of pH, which can limit their utility in a variety of applications. Therefore, it is desirable to identify a class of surfactants that can be tuned, or tailored, to match the application for which they are used

The biological context of HIV-1 host interactions reveals subtle insights into a system hijack

<p>Abstract</p> <p>Background</p> <p>In order to replicate, HIV, like all viruses, needs to invade a host cell and hijack it for its own use, a process that involves multiple protein interactions between virus and host. The HIV-1, Human Protein Interaction Database available at NCBI's website captures this information from the primary literature, containing over 2,500 unique interactions. We investigate the general properties and biological context of these interactions and, thus, explore the molecular specificity of the HIV-host perturbation. In particular, we investigate (i) whether HIV preferentially interacts with highly connected and 'central' proteins, (ii) known phenotypic properties of host proteins inferred from essentiality and disease-association data, and (iii) biological context (molecular function, processes and location) of the host proteins to identify attributes most strongly associated with specific HIV interactions.</p> <p>Results</p> <p>After correcting for ascertainment bias in the literature, we demonstrate a significantly greater propensity for HIV to interact with highly connected and central host proteins. Unexpectedly, we find there are no associations between HIV interaction and inferred essentiality. Similarly, we find a tendency for HIV not to interact with proteins encoded by genes associated with disease. Crucially, we find that functional categories over-represented in HIV-host interactions are innately enriched for highly connected and central proteins in the host system.</p> <p>Conclusions</p> <p>Our results imply that HIV's propensity to interact with highly connected and central proteins is a consequence of interactions with particular cellular functions, rather than being a direct effect of network topological properties. The lack of a propensity for interactions with phenotypically essential proteins suggests a selective pressure to minimise virulence in retroviral evolution. Thus, the specificity of HIV-host interactions is complex, and only superficially explained by network properties.</p

Improving cartilage phenotype from differentiated pericytes in tunable peptide hydrogels

Differentiation of stem cells to chondrocytes in vitro usually results in a heterogeneous phenotype. This is evident in the often detected over expression of type X collagen which, in hyaline cartilage structure is not characteristic of the mid-zone but of the deep-zone ossifying tissue. Methods to better match cartilage developed in vitro to characteristic in vivo features are therefore highly desirable in regenerative medicine. This study compares phenotype characteristics between pericytes, obtained from human adipose tissue, differentiated using diphenylalanine/serine (F2/S) peptide hydrogels with the more widely used chemical induced method for chondrogenesis. Significantly higher levels of type II collagen were noted when pericytes undergo chondrogenesis in the hydrogel in the absence of induction media. There is also a balanced expression of collagen relative to aggrecan production, a feature which was biased toward collagen production when cells were cultured with induction media. Lastly, metabolic profiles of each system show considerable overlap between both differentiation methods but subtle differences which potentially give rise to their resultant phenotype can be ascertained. The study highlights how material and chemical alterations in the cellular microenvironment have wide ranging effects on resultant tissue type

Tunable supramolecular gel properties by varying thermal history

YesThe possibility of using differential pre‐heating prior to supramolecular gelation to control the balance between hydrogen‐bonding and aromatic stacking interactions in supramolecular gels and obtain consequent systematic regulation of structure and properties is demonstrated. Using a model aromatic peptide amphiphile, Fmoc‐tyrosyl‐leucine (Fmoc‐YL) and a combination of fluorescence, infrared, circular dichroism and NMR spectroscopy, it is shown that the balance of these interactions can be adjusted by temporary exposure to elevated temperatures in the range 313–365 K, followed by supramolecular locking in the gel state by cooling to room temperature. Distinct regimes can be identified regarding the balance between H‐bonding and aromatic stacking interactions, with a transition point at 333 K. Consequently, gels can be obtained with customizable properties, including supramolecular chirality and gel stiffness. The differential supramolecular structures also result in changes in proteolytic stability, highlighting the possibility of obtaining a range of supramolecular architectures from a single molecular structure by simply controlling the pre‐assembly temperature.FP7 Ideas: European Research Council. Grant Number: 25877

Alignment of nanostructured tripeptide gels by directional ultrasonication

We demonstrate an in-situ ultrasonic approach to influence self-assembly across the supramolecular to micron length scales, showing enhancement of supramolecular interactions, chirality and orientation, which depends on the peptide sequence and solvent environment. This is the first successful demonstration of using oscillating pressure waves to generate anisotropic organo- and hydro- gels consisting of oriented tripeptides structures

Living biointerfaces based on non-pathogenic bacteria to direct cell differentiation

Genetically modified Lactococcus lactis, non-pathogenic bacteria expressing the FNIII7-10 fibronectin fragment as a protein membrane have been used to create a living biointerface between synthetic materials and mammalian cells. This FNIII7-10 fragment comprises the RGD and PHSRN sequences of fibronectin to bind α5β1 integrins and triggers signalling for cell adhesion, spreading and differentiation. We used L. lactis strain to colonize material surfaces and produce stable biofilms presenting the FNIII7-10 fragment readily available to cells. Biofilm density is easily tunable and remains stable for several days. Murine C2C12 myoblasts seeded over mature biofilms undergo bipolar alignment and form differentiated myotubes, a process triggered by the FNIII7-10 fragment. This biointerface based on living bacteria can be further modified to express any desired biochemical signal, establishing a new paradigm in biomaterial surface functionalisation for biomedical applications