[Axis and rotationally correct positioning of bicondylar femoral prosthesis: preoperative planning and intraoperative implementation]. / Achs- und rotationsgerechte Positionierung des bikondylären Femurschlittens: Präoperative Planung und intraoperative Umsetzung.

BACKGROUND: Clinical outcome and durability of a bicondylar knee endoprosthesis depend on a correct positioning of the femoral prosthesis which should be implanted perpendicularly to the mechanical femoral axis and parallel to the transepicondylar axis to guarantee a harmonic balance of ligaments.. METHOD: Neither the mechanical axis nor the transepicondylar axis can be correctly defined intraoperatively without an instrumental device. Using the method presented here these axes can be determined indirectly using distal and dorsal femoral condyle tangents. Both tangents can be properly defined preoperatively as well as operatively. An x-ray of the whole femur is necessary for the mechanical femoral axis and a thin-layer computed tomography (CT) scan is necessary for the transepicondylar axis. Plug-in sleeves for the 4-in-1 block from 0-13° and a special angle measurement device are required for the operative transfer. RESULTS: This method has been used on 783 patients of whom 38 have been examined in a follow-up study. The deviation of the perpendicular to mechanical axis was on average 0.32° and the average deviation from the parallel to transepicondylar axis was 1.04°. CONCLUSION: The presented procedure is safe and economical and saves operating time.

Putative synaptic vesicle nucleotide transporter identified as glyceraldehyde-3-phosphate dehydrogenase.

Synaptic vesicles isolated from electric ray electric organ have been shown previously to contain a 34-kDa protein that binds azido-ATP, azido-AMP, and N-ethylmaleimide. The protein was found to share similarities with the mitochondrial ADP/ATP carrier and assumed to represent the synaptic vesicle nucleotide transporter. Synaptic vesicles were purified by sucrose density gradient centrifugation and subsequent chromatography on Sephacryl S-1000 from both Torpedo electric organ and bovine brain cerebral cortex. They contained ATP-binding proteins of 35 kDa and 34 kDa, respectively. ATP binding was inhibited by AMP. Both proteins were highly enriched after column chromatography of vesicle proteins on AMP-Sepharose. Antibodies were obtained against both proteins. Antibodies against the bovine brain synaptic vesicle protein of 34 kDa bound specifically to the 35-kDa protein of Torpedo vesicles. An N-terminal sequence obtained against the 34-kDa protein of bovine brain synaptic vesicles identified it as glyceraldehyde-3-phosphate dehydrogenase. The previously observed molecular characteristics of the putative vesicular nucleotide transporter in Torpedo fit those of glyceraldehyde-3-phosphate dehydrogenase. We, therefore, suggest that the protein previously identified as putative nucleotide transporter is, in fact, glyceraldehyde-3-phosphate dehydrogenase.

Svp25, a synaptic vesicle membrane glycoprotein from Torpedo electric organ that binds calcium and forms a homo-oligomeric complex.

Svp25 is a major glycoprotein of cholinergic synaptic vesicles isolated from the Torpedo electric organ. On SDS-PAGE svp25 migrates as a protein of Mr 25,000 and on two dimensional gel electrophoresis separates into several isoforms around a pI of 6.0. It binds concanavalin A and on phase separation with Triton X-114 behaves as an integral membrane protein. Svp25 represents a major vesicular 45Ca2(+)-binding protein. Under non-reducing conditions svp25 forms complexes of higher molecular weight which are multiples of 25,000. Svp25 is contained in the dense web of nerve terminal ramifications at the ventral side of the electroplaque cells. Colloidal gold labelling using a monospecific antibody confirms the selective association of the protein with synaptic vesicles. Although the function of the vesicular svp25 glycoprotein is not known, its ability to bind Ca2+ suggests that it is regulated by activation of the nerve terminal.