[Biodegradable screw versus a press-fit bone plug fixation for ACL reconstruction: a prospective randomized study]. / Biodegradierbare Schraube vs. einer Press-fit-Verankerung für VKB-Rekonstruktionen : Eine prospektive randomisierte Studie.

BACKGROUND: Press-fit fixation of a tendon graft has been advocated in order to achieve tendon to bone healing. HYPOTHESIS: Fixation of a tendon graft with a porous bone scaffold limits bone tunnel enlargement compared with a biodegradable interference screw fixation. METHODS: Between 2005 and 2006, 20 patients (17 men, 3 women) were enrolled in this study for primary reconstruction of the ACL. Patients were randomized to either obtain graft fixation in the tibial tunnel by means of an interference screw (I) or a press-fit fixation with a porous bone cylinder (P). Three months after surgery, a CT scan of the knee was performed and tunnel enlargement was analysed in the coronal and sagittal planes for the proximal, middle and distal thirds of the tunnel. After 6 months, 1 and 2 years, International Knee Documentation Committee (IKDC), Tegner and Lysholm scores of both groups were compared. RESULTS: The bone tunnel enlargement was 106.9±10.9% for group P and 121.9±9.0% for group I (P<0.02) in the AP plane and 102.8±15.2% vs 121.5±10.1% in the coronal plane (P<0.01). IKDC, Tegner, and Lysholm scores improved in both groups from pre- to postoperative assessment without significant differences between the two groups. There was a trend to higher knee stability in group P after 3 months (0.6±1.4 mm vs 1.81±.5 mm, P=0.08). CONCLUSIONS: Both interference screw and a press-fit fixation lead to a high number of good or very good outcomes after ACL reconstruction. Tibial press-fit fixation decreases the amount of proximal bone tunnel enlargement. Press-fit fixation decreases the amount of proximal bone tunnel enlargement and improves bone to tendon contact.

Expression of Erwinia uredovora Phytoene Desaturase in Synechococcus PCC7942 Leading to Resistance against a Bleaching Herbicide.

The gene coding for phytoene desaturase of the bacterium Erwinia uredovora (crtI) was inserted into the chromosome of the cyanobacterium Synechococcus PCC7942 strain R2-PIM8. For expression of crtI in the heterologous host, two constructs with different promoters were introduced into Synechococcus. In the first, crtI was fused to the 5[prime] region of the psbA gene of the xanthophycean microalga Bumilleriopsis filiformis. The second construct carried crtI inserted downstream of the neomycin phosphotransferase II gene (nptII) from the transposon Tn5. Expression of crtI under the control of the respective promoter was shown by immunodetection of the gene product. The functionality of the heterologously expressed phytoene desaturase CRTI in the transformants was demonstrated by enzymic assays. The transformants acquired very strong resistance toward the bleaching herbicide norflurazon.