Percutaneous minimally invasive repair of acromioclavicular joint dislocation using cannulated screws under ultrasonic vs. C-arm navigation: A prospective trial.

INTRODUCTION: To compare percutaneous minimally invasive repair (PMIR) of acute acromioclavicular (AC) joint dislocation under ultrasound guidance (PMIR-UN) vs. C-arm navigation (PMIR-CN). HYPOTHESIS: PMIR-UN has similar functional and radiographic outcomes as PMIR-CN. MATERIALS AND METHODS: We treated 48 patients with acute grade III or V AC joint dislocation with surgical reduction and fixation with Kirschner wires and cannulated screws. The patients were randomly divided into a PMIR-UN group (n=24) and a PMIR-CN group (n=24). We assessed functional outcomes, operative duration, incision length, and intraoperative radiation exposure. Shoulder joint function was evaluated with the Constant-Murley score, and postoperative efficacy was evaluated using the Karlsson criteria. RESULTS: The median follow-up duration was 13 months (range, 8-18 months). Satisfactory functional outcomes were obtained in both groups. Incision length, incidence of postoperative infection, pin migration, and postoperative efficacy did not differ between the two groups. Operative duration and intraoperative radiation dose were significantly greater in the PMIR-CN group than in the PMIR-UN group (P<0.05). Kirschner wires were removed at 4 weeks after surgery, and cannulated screws were removed at 12 weeks after surgery in both groups. DISCUSSION: Based on the satisfactory results obtained in all patients, we conclude that PMIR-UN is a safe, easy, and reliable technique for the treatment of acute grade III or V AC joint dislocation. TYPE OF STUDY: Low-powered prospective randomized trial. LEVEL OF EVIDENCE: Level II.

Structure of a DNA-bisdaunomycin complex.

The application of detailed structural data bases has now culminated in the successful design of a new generation of bisanthracyclines that form ultratight DNA complexes [Chaires, J. B., Leng, F., Przewloka, T., Fokt, I., Ling, Y. H., Perez-Soler, R., & Priebe, W. (1997) J. Med. Chem. 40, 261-266]. Daunomycin dimers were designed to bind to DNA in complexes resembling those of monomers intercalated at adjacent sites. The goal of the work described here was to determine, with X-ray crystallography, if a potent member of this newly designed and synthesized class of bisanthracyclines (WP631) binds as intended. WP631 is composed of two daunomycin molecules, linked N3' to N3' by a xylyl group. We have solved the 2.2 A X-ray crystal structure of a complex of WP631 bound to [d(CGATCG)]2. We demonstrate, on a detailed molecular level, that the WP631 design strategy is a success. The structures of WP631 and two daunomycin molecules bound to [d(CGATCG)]2 provide the unprecedented opportunity for detailed comparison of mono- and bis-intercalated complexes of the same chromophore, allowing us to distinguish effects of mono-intercalation from those of bis-intercalation. Differences are focused primarily in the centers of the complexes. DNA unwinding and other helical distortions propagate more efficiently to the center of the WP631 complex than to the center of the daunomycin complex.

Crystallographic structure of a multiple beta-turn containing, glycine-rich heptapeptide: a synthetic precursor of the lipopeptaibol antibiotic trichodecenin I.

In continuation of our studies on the structure and function of peptaibol antibiotics, the conformational properties of a sequence analogous to that of Trichodecenin I (Z-Gly-Gly-D-Leu-Aib-Gly-D-Ile-D-Leu-OMe, where Z = benzyloxycarbonyl, Aib = alpha-aminoisobutyric acid, and OMe = methyl ester) have been investigated crystallographically. This sequence is the mirror image of the naturally occurring molecule and also of the C-terminal heptapeptide of the related lipopeptaibol Trichogin A IV (where, however, the Leu-OMe residue has replaced the original Leuol residue). The molecule crystallized in the monoclinic system, space group P21, Z = 4, and cell parameters a = 11.610(5), b = 33.342(8), c = 11.735(4) A, beta = 110.42(1) degrees, V = 4257(3) A3. The crystallographic refinement converges at residual values of R = 0.047 and wR2 = 0.134 on F2. In the 1-5 segment the molecular conformation is virtually identical to that one reported from solution nmr studies of a similarly protected sequence [Biopolymers (1995), Vol. 35. pp. 21-29)] and is characterized by beta-turns of type I at Gly1-Gly2, II' at Leu3-Aib4, and I at Aib4-Gly5. In the crystal structure, a beta-sheet-like arrangement is seen at the C-terminus.

Structure determination of racemic trichogin A IV using centrosymmetric crystals.

Direct methods of crystal structure solution are greatly facilitated in centrosymmetric space groups where the complexity of the phase-problem is reduced. For most peptides and proteins, crystallization in a centrosymmetric arrangement is precluded by an intrinsic dissymmetry due to the constituent chiral amino acid residues. The synthetic accessibility of peptide sequences containing amino acids of either chirality offers the possibility for co-crystallization of racemic crystals. We report here the first use of such an approach for the de novo structure determination of a medium-sized molecule, trichogin A IV, which is a constituent of a fungal lipopeptaibol mixture possessing membrane-modifying properties of biological interest.