Action minimizing fronts in general FPU-type chains

We study atomic chains with nonlinear nearest neighbour interactions and prove the existence of fronts (heteroclinic travelling waves with constant asymptotic states). Generalizing recent results of Herrmann and Rademacher we allow for non-convex interaction potentials and find fronts with non-monotone profile. These fronts minimize an action integral and can only exists if the asymptotic states fulfil the macroscopic constraints and if the interaction potential satisfies a geometric graph condition. Finally, we illustrate our findings by numerical simulations.Comment: 19 pages, several figure

Dimeric integrin a5ß1 ligands confer morphological and differentiation responses to murine embryonic stem cells

We present the first report utilizing, and showing the functional relevance of, self-assembling polyvalent ligands specific for integrin α5β1 in murine embryonic stem (mES) cell adhesion. Di, tri and tetrameric 9th-10th type III fibronectin domains (FIII9′10) were used to generate clustered integrin α5β1 ligand surfaces for mES cell culture. Compared to gelatin, FIII9′10 (monomer), FIII9′10-trimer and -tetramer, the FIII9′10-dimer supported the highest number of mES cell colonies. No evidence of domain unfolding upon surface adsorption was found. Colonies appeared disperse with a spread cell morphology unless subdued back to a tight morphology with increasing concentrations of leukemia inhibitory factor (LIF). In the presence of LIF, mES cells adherent to the FIII9′10-dimer showed transient upregulation of Oct-4, the mesodermal transcription factor, Brachyury, and the ectodermal marker, Nestin. However, dual upregulation of Nanog maintained the mES cells in a pluripotent state, confirmed by alkaline phosphatase staining. Therefore, the behavior of mES cells adherent to dimeric integrin α5β1 ligands is a largely morphological phenomenon conferring pro-differentiation signals towards mesodermal and ectodermal lineages. This work will be of interest to cell and tissue engineering groups aiming to control ES cell behavior through integrin ligand presentation and synthetic substrates

Entwicklung eines beruehrungsfreien mikrooptischen Tonometers zur Messung des Augeninnendruckes durch Stimulation von Oberflaechenschwingungen und Messung der Bulbusvariation. Mikrooptisches Tonometer (MIOPTO) Gemeinsamer Schlussbericht

SIGLEAvailable from TIB Hannover: F03B945+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung und Forschung, Berlin (Germany)DEGerman

Self-assembling multimeric integrin 5β1 ligands for cell attachment and spreading

Substrates utilising clustered arginine-glycine-aspartic acid (RGD) ligand displays support greater cell adhesion over random displays. However, cell adhesion to integrin 5β1 requires the synergy site on the 9th type III fibronectin domain (FIII) in addition to RGD on the 10th FIII domain. Here, we have designed and expressed soluble protein chimeras consisting of an N-terminal 9th-10th FIII domain pair, IgG-derived hinge and leucine zipper-derived helix; the latter mutated to yield di-, tri- and tetrameric coiled coils and thus self-assembling, multimeric integrin 5β1 ligands. A unique C-terminal cysteine was appended to the helix to facilitate 'anchoring' of the chimeras with a defined orientation on a surface. Size-exclusion chromatography and circular dichroism demonstrated that the chimeras self-assembled as multimers in solution with defined secondary structures predicted from theoretical calculations. Biotinylation via a thioether bond was used to selectively bind the chimeras to streptavidin-coated surfaces, each of which was then shown to bind integrin 5β1 by surface plasmon resonance. Spreading of fibroblasts to surfaces derivatised with the chimeras was found to proceed in the order: tetramer > trimer > dimer > monomer. Thus, we describe novel polyvalent integrin 5β1 ligands for facile derivatisation of substrates to improve cell adhesion in vitro