Detection of ubiquityl-calmodulin conjugates with a novel high-molecular weight ubiquitylprotein-isopeptidase in rabbit tissues

The selective degradation of many proteins in eukaryotic cells is carried out by the ubiquitin system. In this pathway, proteins are targeted for degradation by covalent ligation to ubiquitin, a highly conserved protein [1]. Ubiquitylated proteins were degraded by the 26S protea-some in an ATP-depended manner. The degradation of ubiquitylated proteins were controlled by isopeptidase cleavage. A well characterised system of ubiquitylation and deubiquitylation is the calmodulin system in vitro [2]. Detection of ubiquityl-calmodulin conjugtates in vivo have not been shown so far. In this article we discuss the detection of ubiquitin calmodulin conjugates in vivo by incubation with a novel high-molecular weight ubiquitylprotein-isopeptidase in rabbit tissues. Proteins with a molecular weight of ubiquityl-calmodulin conjugates could be detected in all organs tested. Incubation with ubiquitylprotein-isopeptidase showed clearly a decrease of ubiquitin calmodulin conjugates in vivo with an origination of unbounded ubiquitin. These results suggest that only few ubiquitin calmodulin conjugates exist in rabbit tissues

Local Application of BMP-2 Specific Plasmids in Fibrin Glue does not Promote Implant Fixation

<p>Abstract</p> <p>Background</p> <p>BMP-2 is known to accelerate fracture healing and might also enhance osseointegration and implant fixation. Application of recombinant BMP-2 has a time-limited effect. Therefore, a gene transfer approach with a steady production of BMP-2 appears to be attractive. The aim of this study was to examine the effect of locally applied BMP-2 plasmids on the bone-implant integration in a non-weight bearing rabbit tibia model using a comparatively new non-viral copolymer-protected gene vector (COPROG).</p> <p>Methods</p> <p>Sixty rabbits were divided into 4 groups. All of them received nailing of both tibiae. The verum group had the nails inserted with the COPROG vector and BMP-2 plasmids using fibrin glue as a carrier. Controls were a group with fibrin glue only and a blank group. After 28 and 56 days, these three groups were sacrificed and one tibia was randomly chosen for biomechanical testing, while the other tibia underwent histomorphometrical examination. In a fourth group, a reporter-gene was incorporated in the fibrin glue instead of the BMP-2 formula to prove that transfection was successful.</p> <p>Results</p> <p>Implant fixation strength was significantly lower after 28 and 56 days in the verum group. Histomorphometry supported the findings after 28 days, showing less bone-implant contact.</p> <p>In the fourth group, successful transfection could be confirmed by detection of the reporter-gene in 20 of 22 tibiae. But, also systemic reporter-gene expression was found in heterotopic locations, showing an undesired spreading of the locally applied gene formula.</p> <p>Conclusion</p> <p>Our results underline the transfecting capability of this vector and support the idea that BMP-2 might diminish osseointegration. Further studies are necessary to specify the exact mechanisms and the systemic effects.</p

Osteoinductive potential and periimplant bone formation of immobilized rhBMP-2 on titanium implants in a gap healing model in sheep

Tom Norman's show with banner for 'Tommy 'Toes' Jacobsen/Armless Pianist/Electronic Organist' photographed at Oxford St Giles Fair, 1957

Histologische Untersuchungen von Bone-Morphogenetic-Protein-2-beschichteten Titanimplantaten im Mittelohr des Kaninchens.

Einleitung: Die osteoinduktive Potenz von rekombinantem humanen knochenmorphogenetischen Protein-2 (rhBMP-2) konnte bisher für Lamellenknochen nachgewiesen werden. Einzelne Erfahrungen für das Mittelohr liegen im Tierversuch für lösliches rhBMP-2 vor. Kürzlich ist es gelungen, durch Oberflächenmodifikation von Titanoberflächen rhBMP-2 kovalent auf diesen zu binden. Methoden und Ergebnisse: Bei 18 Kaninchen (36 Mittelohren) wurde durch Spaltüberbrückungsversuche die Knochenneubildung (Dünnschliffpräparate, digitale Morphometrie) in Implantatnähe erfasst für 1.: Titanimplantate und Zugabe von löslichem rhBMP-2, 2.: rhBMP-2-beschichtete- und 3.: Kontroll-Implantate. Hierbei konnte die verbesserte Osseointegration von rhBMP-2-beschichteten Titanimplantaten im Mittelohr nachgewiesen werden. Schlussfolgerungen: Erstmals wurde die Wirksamkeit rhBMP-2-beschichteter Titan-Implantate im Mittelohr nachgewiesen. Zukünftige Untersuchungen müssen den Stellenwert solcher Implantate für die rekonstruktive Mittelohrchirurgie (Ossikelrekonstruktion, Obliterationen, Rekonstruktion der hinteren Gehörgangswand) evaluieren