Camouflaged angiogenic BMP-2 functions exposed by pico-paracrine biohybrids

The constant release of human bone morphogenetic protein 2 (rhBMP-2) in the picomolar range (Pico-Stat) from PDLLA-biohybrids led to the detection of intrinsic novel pro- and anti-angiogenic functions of this cytokine. As integrant part in this perspective of previous work, first evidence for the binding of rhBMP-2, as an inverse agonist, to allosteric angiogenic receptors in cocultures of human endothelial cells is reported

ZUM MECHANISMUS DER PROTEINADSORPTION AN HYDROPHOBEN GELOBERFLÄCHEN

Alkylreste mit einer Kettenlänge von 1-4 C-Atomen wurden mit Hilfe der BrCN-Methode kovalent an einem hydrophilen Trägergel (Agarose, Sepharose 4B [Pharmacia, Uppsala) immobilisiert. Die immobilisierten Alkylreste bilden auf der Geloberfläche ein zweidimensionales Bindungsstellengitter, an dem Proteine adsorbiert werden können. Die Bindung von Proteinen ist komplex und verläuft nicht nach den Gesetzmäßigkeiten einer Langmuir-Isotherme. Besondere Merkmale der Proteinadsorption an solchen Geloberflächen sind Kooperativität und Hysterese. Eine positive Kooperativität der Adsorption wird in Abhängigkeit von der Oberflächenkonzentration der immobilisierten Alkylreste beobachtet. Eine negative Kooperativität der Adsorption findet man in Abhängigkeit von der Proteinkonzentration. Die Hysterese ist ein Ausdruck der thermodynamischen Irreversibilität der Adsorption und des Fehlens eines Gleichgewichtsüberganges

A macrophage model of osseointegration

The mechanisms of peri-implant de novo bone formation and contact osteogenesis are still largely unknown. In 1984 Donath et al. showed that macrophages were the first cells to colonize a titanium implant. Recently it was shown that that there are inflammatory (M1) and healing macrophages (M2), the latter of which can secrete BMP 2. In the context of data from a gap healing experiment a macrophage model of osseointegration is suggested

Advanced wettability analysis of implant surfaces

New methodologies are a major driving force of scientific progress. In this case the finding that contact angles can be expressed as complex numbers offers the possibility of a much refined analysis beyond zero degrees of rough ultra-/superhydrophilic, (now called hyperhydrophilic), metal surfaces, which play a distinct role in dental and orthopedic implantology. The approaches, a short theoretical introduction and examples from medical applications are given

Ubiquitination of endogenous calmodulin in rabbit tissue extracts

AbstractPreviously we were able to show that purified calmodulins from vertebrates, plants (spinach) and the mold Neurospora crassa can be covalently conjugated to ubiquitin in a Ca2+-dependent manner. It was therefore pertinent to answer the question if a tissue extract contains all the components necessary for the endogenous synthesis of ubiquityl calmodulin (uCaM). Therefore [125I]ubiquitin, ATP/Mg2+ and Ca2+ were added to tissue extracts enriched by a single ion exchange step. In such extracts of red blood cells, skeletel muscle and testis a novel ubiquitin conjugate of 27–29 kDa is formed. This novel band could be identified as ubiquityl-calmodulin by the following methods: (i) identical R1-value of novel conjugate and standard uCaM in SDS-PAGE; (ii) Ca2+-dependent conjugate formation; (iii) Ca2+-dependent adsorption to fluphenazine-Sepharose; (iv) Ca2+-dependent mobility change of the novel conjugate during SDS-PAGE; and (v) inhibition of conjugate band formation by phosphorylate kinase. These experiments clearly demonstrate that ubiquityl calmodulin can be endogenously generated in enriched cellular extracts and strongly indicate that this reaction is of importance in vivo

Protecting ultra- and hyperhydrophilic implant surfaces in dry state from loss of wettability

Ultrahydrophilic titanium miniplates with sandblasted and acid etched (SLA) surfaces were protected from loss of hydrophilicity by an exsiccation layer of salt and stored in a dry state. Various salts in different concentrations were tested in respect to their conservation capacity and optical appearance. Potassium phosphate buffer in a specified composition appeared to be optimal. This optimal system was applied in a long time storage experiment showing no loss of hydrophilicity over years. It was also transferred with success to hyperhydrophilic dental implants

Antimicrobial and Osseointegration Properties of Nanostructured Titanium Orthopaedic Implants

The surface design of titanium implants influences not only the local biological reactions but also affects at least the clinical result in orthopaedic application. During the last decades, strong efforts have been made to improve osteointegration and prevent bacterial adhesion to these surfaces. Following the rule of “smaller, faster, cheaper”, nanotechnology has encountered clinical application. It is evident that the hierarchical implant surface micro- and nanotopography orchestrate the biological cascades of early peri-implant endosseous healing or implant loosening. This review of the literature gives a brief overview of nanostructured titanium-base biomaterials designed to improve osteointegration and prevent from bacterial infection

Recognition hysteresis of the acetylcholine receptor of torpedo californica

Neumann E, Boldt E, Rauer B, Wolf H, Chang HW. Recognition hysteresis of the acetylcholine receptor of torpedo californica. In: Jennissen HP, ed. 7th International Symposium on Affinity Chromatography and Interfacial Macromolecular Interactions: held in Oberammergau, F.R.G., 17 - 21 Aug., 1987. Die makromolekulare Chemie : Macromolecular symposia ; 17. Basel: Hüthig und Wepf; 1988: 1-16