Injury potential of one-litre beer steins.

Injuries resulting from blows with beer steins are a frequent occurrence during annual autumn fairs or at beer halls in South Germany and Austria. The majority of these cases are tried in court and thus being assessed by a forensic medicine expert. The article at hand gives a short overview on the injury potential of one-litre beer steins and explains the key variables to consider when analyzing beer stein injuries. On the basis of representative cases, which were assessed by specialists from the Institute of Legal Medicine of the Munich University over the last 5 years, the main biomechanical aspects and resulting injuries of one-litre beer stein assaults are discussed. Several severe and potentially life-threatening injuries have been observed after an assault with a one-litre beer stein. There is a discrepancy between the mechanical stability of brand new and used steins and the corresponding injuries, which can be explained by a decrease in impact tolerance of the steins with their use. In general, a blow with a one-litre glass or stonework beer stein to the head can cause severe and even life-threatening blunt as well as sharp trauma injuries.

A molecular toolkit for the functionalization of titanium-based biomaterials that selectively control integrin-mediated cell adhesion.

We present a click chemistry-based molecular toolkit for the biofunctionalization of materials to selectively control integrin-mediated cell adhesion. To this end, α5ß1-selective RGD peptidomimetics were covalently immobilized on Ti-based materials, and the capacity to promote the selective binding of α5ß1 was evaluated using a solid-phase integrin binding assay. This functionalization strategy yielded surfaces with a nine-fold increased affinity for α5ß1, in comparison to control samples, and total selectivity against the binding of the closely related integrin αvß3. Moreover, our methodology allowed the screening of several phosphonic acid containing anchoring units to find the best spacer-anchor moiety required for establishing an efficient binding to titanium and to promote selective integrin binding. The integrin subtype specificity of these biofunctionalized surfaces was further examined in vitro by inducing selective adhesion of genetically modified fibroblasts, which express exclusively the α5ß1 integrin. The versatility of our molecular toolkit was proven by shifting the cellular specificity of the materials from α5ß1- to αvß3-expressing fibroblasts by using an αvß3-selective peptidomimetic as coating molecule. The results shown here represent the first functionalization of Ti-based materials with α5ß1- or αvß3-selective peptidomimetics that allow an unprecedented control to discriminate between α5ß1- and αvß3-mediated adhesions. The role of these two integrins in different biological events is still a matter of debate and is frequently discussed in literature. Thus, such bioactive titanium surfaces will be of great relevance for the study of integrin-mediated cell adhesion and the development of new biomaterials targeting specific cell types.

Behavior of primary human osteoblasts on trimmed and sandblasted Ti6Al4V surfaces functionalized with integrin αvß3-selective cyclic RGD peptides.

It is well known that functionalization of surfaces with cell adhesive peptides mimicking the integrin binding motif of extracellular matrix proteins is a feasible approach to improve osseointegration of implant materials. Also, modification of the surface properties of the material (e.g., roughness) strongly influences cell behavior. However, these two approaches are rarely studied together. This study addressed the hypothesis that the combination of peptide functionalization and surface roughness will have an enhancing effect on the adhesion process of osteoblasts. To test this hypothesis, a series of αvß3-selective cyclic RGD peptides were prepared and immobilized on trimmed (S(a) = 0.74 µm, smooth) and sandblasted (S(a) = 3.24 µm, rough) Ti6Al4V disks. Effects of these surface modifications were evaluated with respect to integrin αvß3-mediated adhesive capacity, cell morphology, and spreading of primary human osteoblasts. After 3 h of incubation, osteoblasts adhered more strongly on sandblasted than on trimmed noncoated Ti6Al4V surfaces. Their attachment efficiency was further enhanced in the presence of RGD peptides. However, peptide functionalization had a relatively stronger impact on osteoblast attachment on trimmed surfaces compared with sandblasted surfaces. Cell morphology after 3 h of culture was exclusively altered by surface topography. RGD coating was critical for osteoblast spreading on both trimmed and sandblasted materials after 1 h of incubation but it showed almost negligible effects after 3 h. The results of this study provide evidence that the alliance of RGD coating and surface topography on Ti6Al4V positively influences osteoblast adhesion and spreading, especially at very early adhesion times.