Volume-stable collagen matrices (VSCM) are conductive for the connective tissue upon soft tissue augmentation. Considering that collagen has osteoconductive properties, we have investigated the ...possibility that the VSCM also consolidates with the newly formed bone. To this end, we covered nine rat calvaria circular defects with a VSCM. After four weeks, histology, histomorphometry, quantitative backscattered electron imaging, and microcomputed tomography were performed. We report that the overall pattern of mineralization inside the VSCM was heterogeneous. Histology revealed, apart from the characteristic woven bone formation, areas of round-shaped hypertrophic chondrocyte-like cells surrounded by a mineralized extracellular matrix. Quantitative backscattered electron imaging confirmed the heterogenous mineralization occurring within the VSCM. Histomorphometry found new bone to be 0.7 mm2 (0.01 min; 2.4 max), similar to the chondrogenic mineralized extracellular matrix with 0.7 mm2 (0.0 min; 4.2 max). Microcomputed tomography showed the overall mineralized tissue in the defect to be 1.6 mm3 (min 0.0; max 13.3). These findings suggest that in a rat cranial defect, VSCM has a limited and heterogeneous capacity to support intramembranous bone formation but may allow the formation of bone via the endochondral route.
The arachidonic acid cascade is a key player in inflammation, and numerous well-established drugs interfere with this pathway. Previous studies have suggested that simultaneous inhibition of ...5-lipoxygenase (5-LO) and soluble epoxide hydrolase (sEH) results in synergistic anti-inflammatory effects. In this study, a novel prototype of a dual 5-LO/sEH inhibitor
was rationally designed and synthesized.
was evaluated in enzyme activity assays with recombinant enzymes. Furthermore, activity of
in human whole blood and endothelial cells was investigated.
potently inhibited both enzymes in vitro and attenuated the formation of leukotrienes in human whole blood.
was also tested in a cell function-based assay. The compound significantly inhibited the LPS-induced adhesion of leukocytes to endothelial cells by blocking leukocyte activation.
Caking of powders and bulk granules and adhesion of powders on equipment surfaces is a serious problem in the food, chemical and pharmaceutical industries. While caking of crystalline particles is ...tackled only briefly, this publication deals mainly with caking of water-soluble amorphous particles. Caking of amorphous particles starts with stickiness of the powder surface and can result in a collapse of the powder structure. The powder bulk turns from a free flowable powder bulk composed of single particles into a massive block. The material aspects (hygrocapacity, hygrosensitivity and viscosity) of water-soluble amorphous materials and sintering are discussed. The increase of the sinter bridges during caking could be modelled through the known sinter equations and measured by carrying out experiments in a ring shear cell. The calculated sinter bridge diameter could be correlated with the strength of the caked powder bulk measured in a ring shear tester.
Caking of amorphous particles starts with stickiness of the powder surface and can result in a collapse of the powder structure. The increase of the sinter bridges during caking could be modelled through the known sinter equations. The calculated sinter bridge diameter could be correlated with the strength of the caked powder bulk measured in a ring shear tester.
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Lectins are proteins or glycoproteins from plants, animals or microorganisms, which typically bind specifically to sugar residues, e.g., located in cell walls or membranes. This reaction might change ...the physiology of the cell wall and influences the metabolism inside the cell. Some lectins of plants stimulate the immune system by unspecific activation of T-cells or influence cell division; others cause agglutination of cells (e.g., erythrocytes) and are therefore from therapeutic interest.
In a new approach, biomolecular interaction analysis (BIA) was utilised for a screening program on lectins. The BIA has been done by surface plasmon resonance (SPR). The system can be used either for characterisation of lectin-binding domains or for a screening on lectins from natural sources. Several lectin-binding surfaces on the basis of SPR have been established.
The behavior of mixed-ligand-coated gold nanoparticles at a liquid−liquid interface during compression has been investigated. The system was characterized by measuring pressure−area isotherms and by ...simultaneously performing in situ X-ray studies. Additionally, Monte Carlo (MC) simulations were carried out in order to interpret the experimental findings. With this dual approach it was possible to characterize and identify the different stages of compression and understand what happens microscopically: first, a compression purely in-plane, and, second, the formation of a second layer when the in-plane pressure pushes the particles out of the plane. The first stage is accompanied by the emergence of an in-plane correlation peak in the scattering signal and a strong increase of the pressure in the isotherm. The second stage is characterized by the weakening of the correlation peak and a slower increase in pressure.
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We investigate the influence of the coordination of cross-links on the plastic (i.e., permanent) deformation in cross-linked fiber bundles. Yield strain and strength as well as the ...resilience are studied as a function of cross-linker and grafting density. It is found that classical twofold coordinated cross-links lead to a pronounced strain concentration in the system, while cross-links with higher coordination allow for a more homogeneous load transfer through the system. This results in inferior mechanical properties related to plastic behavior in the first system compared to the latter. Particularly, in twofold coordinated systems, the resilience shows a non-monotonic behavior with respect to cross-linker density. This means that inserting always more and stronger cross-links do not necessarily improve the mechanical performance of a material. These findings may help to interpret experimental findings on the fracture energy in hydro-gels cross-linked with zinc ions.
Bilayer structures in catanionic systems experimentally showed peculiar mechanical behavior. The observed increase in the bending stiffness is supposedly connected to additional hydrogen bonds ...forming between anionic headgroups. With a simple model, we can explain the extreme sensitivity of the bending stiffness of the membrane on the molar ratio of the charged molecules. This effect is further amplified by the sandwichlike structure of the membrane, where the apolar core separating the headgroups acts via a kind of lever-arm principle. As a consequence of these combined effects, the model membrane changes from a soft behavior with bending rigidities on the order of 10k(B)T to an extremely stiff membrane with a bending stiffness more than 2 orders of magnitude larger where most of this change occurs within a molar ratio interval smaller than 0.1.
We investigate the remodeling process of trabecular bone inside a human vertebral body using a stochastic lattice model, in which the ability of living bone to adapt to mechanical stimuli is ...incorporated. Our simulations show the emergence of a networklike structure similar to real trabecular bone. With time, the bone volume fraction reaches a steady state. The microstructure, however, coarsens with a typical length in the system following a power law. The simulation results suggest that a coarsening of the trabecular structure should occur as a natural aging phenomenon, not related to disease.
The β/α barrel is the common protein fold of numerous enzymes and was proposed recently to be the result of gene duplication and fusion of an ancient half-barrel. The initial enzyme of shikimate ...biosynthesis possesses the additional feature of feedback regulation. The crystal structure and kinetic studies on chimera and mutant proteins of yeast 3-deoxy-D-arabino-heptulosonate-7-phosphate (DAHP) synthase from Saccharomyces cerevisiae inhibited by phenylalanine (Aro3p) and DAHP synthase S. cerevisiae inhibited by tyrosine (Aro4p) give insight into important regions for regulation in the enzyme: The loop, which is connecting the two half-barrels, and structural elements added to the barrel are prerequisites for regulation and form a cavity on the N-terminal side of the β/α barrel. In the cavity of Aro4p at position 226 is a glycine residue, which is highly conserved in all other tyrosine-regulated DAHP synthases as well. Sequence alignments with phenylalanine-regulated DAHP synthases including Aro3p show a highly conserved serine residue at this position. An exchange of glycine to serine and vice versa leads to a complete change in the regulation pattern. Therefore the evolution of these differently feedback-inhibited isoenzymes required gene duplication and a single mutation within the internal extra element. Numerous additional amino acid substitutions present in the contemporary isoenzymes are irrelevant for regulation and occurred independently.
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