[Comparative study on the strength of different mechanisms of operation of multidirectionally angle-stable distal radius plates]. / Vergleichende Studie zur statischen Festigkeit unterschiedlicher Verblockungsmechanismen multidirektional winkelstabiler Verriegelungen distaler Radiusplatten.

INTRODUCTION: Polyaxial angle-stable plating is thought to be particularly beneficial in the management of complex intra-articular fractures of the distal radius. The present study was performed to investigate the strength of polyaxial locking interfaces of distal radius plates. MATERIAL AND METHODS: We tested the polyaxial interfaces of 3 different distal radius plates (2.4 mm Variable Angle LCP Two-Column Volar Distal Radius Plate, Synthes, Palmar Classic, Königsee Implantate and VariAx Plate Stryker). The strength of 0° and 10° screw locking angle was obtained during static loading. RESULTS: The strength of Palmar Classic with a 0° locking angle is significantly the best of all tested systems. With a 10° locking angle there is no significant difference between Palmar Classic, Two column Plate and VariAx Plate. CONCLUSION: The strength of polyaxial interfaces differs between the tested systems. A reduction of ultimate strength is due to increases of screw locking angle. The design of polyaxial locking interfaces should be investigated in human bone models.

The complete mitochondrial genome of Radix balthica (Pulmonata, Basommatophora), obtained by low coverage shot gun next generation sequencing.

A 454-FLX low-coverage sequencing approach was used to assemble the mitochondrial genome of Radix balthica. The mtDNA sequence is 13,993 nt long and contains 37 genes (13 protein coding genes, two rRNAs and 22 tRNAs). Four genes, the 12S RNA and seven tRNAs are transcribed in reverse order. The sequence is AT rich (71.3%), similar to other basommatophoran species. Comparison with the most closely related mt genomes available (Biomphalaria glabrata and Biomphalaria tenagophila) revealed identical gene orders except for five tRNAs. Next generation sequencing proved to be a fast and easy method for sequencing an entire mitochondrial genome.

Tracing the D-pathway in reconstituted site-directed mutants of cytochrome c oxidase from Paracoccus denitrificans.

Heme-copper terminal oxidases use the free energy of oxygen reduction to establish a transmembrane proton gradient. While the molecular mechanism of coupling electron transfer to proton pumping is still under debate, recent structure determinations and mutagenesis studies have provided evidence for two pathways for protons within subunit I of this class of enzymes. Here, we probe the D-pathway by mutagenesis of the cytochrome c oxidase of the bacterium Paracoccus denitrificans; amino acid replacements were selected with the rationale of interfering with the hydrophilic lining of the pathway, in particular its assumed chain of water molecules. Proton pumping was assayed in the reconstituted vesicle system by a stopped-flow spectroscopic approach, allowing a reliable assessment of proton translocation efficiency even at low turnover rates. Several mutations at positions above the cytoplasmic pathway entrance (Asn 131, Asn 199) and at the periplasmic exit region (Asp 399) led to complete inhibition of proton pumping; one of these mutants, N131D, exhibited an ideal decoupled phenotype, with a turnover comparable to that of the wild-type enzyme. Since sets of mutations in other positions along the presumed course of the pathway showed normal proton translocation stoichiometries, we conclude that the D-pathway is too wide in most areas above positions 131/199 to be disturbed by single amino acid replacements.