Percutaneous posterolateral lumbar discectomy and decompression with a 6.9-millimeter cannula. Analysis of operative failures and complications.

The operative failures and complications of percutaneous posterolateral lumbar discectomy were analyzed in 100 patients who had a herniated nucleus pulposus and were prospectively studied and treated with use of a 6.9-millimeter outer-diameter (4.9-millimeter inner-diameter) sheath and manual insertion of the instruments. Twelve operations were considered to have failed, regardless of the length of postoperative follow-up or the incidence of reinjury; eleven patients had a repeat operation at the index level, and one patient was a chronic drug-abuser. In eight of the eleven patients, subsequent laminectomy was successful. Two patients had a psoas hematoma and one had a transitory sensory and distal motor deficit; all of these complications resolved without sequelae. There were no major complications, including superficial or deep infection, and no patient had neurovascular compromise.     

Beitrag zur Lehre der cerebralen Schmerzen

Ohne Zusammenfassung     

Hierarchy of simulation models in predicting structure and energetics of the Src SH2 domain binding to tyrosyl phosphopeptides.

Structure and energetics of the Src Src Homology 2 (SH2) domain binding with the recognition phosphopeptide pYEEI and its mutants are studied by a hierarchical computational approach. The proposed structure prediction strategy includes equilibrium sampling of the peptide conformational space by simulated tempering dynamics with the simplified, knowledge-based energy function, followed by structural clustering of the resulting conformations and binding free energy evaluation of a single representative from each cluster, a cluster center. This protocol is robust in rapid screening of low-energy conformations and recovers the crystal structure of the pYEEI peptide. Thermodynamics of the peptide-SH2 domain binding is analyzed by computing the average energy contributions over conformations from the clusters, structurally similar to the predicted peptide bound structure. Using this approach, the binding thermodynamics for a panel of studied peptides is predicted in a better agreement with the experiment than previously suggested models. However, the overall correlation between computed and experimental binding affinity remains rather modest. The results of this study show that small differences in binding free energies between the Ala and Gly mutants of the pYEEI peptide are considerably more difficult to predict than the structure of the bound peptides, indicating that accurate computational prediction of binding affinities still remains a major methodological and technical challenge.     

Digital imaging of the chest

During the past several years, image acquisition in nuclear medicine, computed tomography, ultrasonography, subtraction angiography, and magnetic resonance has been by digitization. Despite these advances, research in the development of digital imaging in conventional radiography has lagged behind. Although studies with a variety of digital techniques have been carried out on several fronts, we still do not possess a method that has captured the imagination of the majority of radiologists and other physicians to a point where it could replace conventional screen-film imaging. This article reviews the current status and general principles of the technology, focusing on the four digital radiographic techniques that have shown the greatest promise - film digitization, an image intensifier - based system, photostimulable phosphor plates, and a scanned projection system. The physical aspects of each of the four systems and the clinical results that have been reported to date, as well as the advantages and disadvantages of each system, are presented.