Preoperative planning using computed tomography in tibial plateau levelling osteotomy: A comparison with conventional radiography

Abstract Background Tibial plateau levelling osteotomy (TPLO) is currently one of the most common surgical procedures for the correction of the stifle joint with a ruptured cranial cruciate ligament. TPLO is based on the preoperative tibial plateau angle (TPA); therefore, it is essential to optimise the consistency and repeatability of TPA measurements. Objectives This study aims to compare computed tomography (CT) with conventional radiography in the preoperative planning of TPLO. Methods This prospective study included six dogs (12 hindlimbs) and 13 canine cadaveric hindlimbs. In the six beagle dogs, TPAs were measured by three radiologists using digital radiographic and CT images to evaluate the intra‐ and inter‐observer agreement. To evaluate the intra‐observer agreement of the TPA before and after surgery, and the intended angle of the postoperative TPA according to the preoperative planning method, 13 cadaveric hindlimbs were evaluated thrice at random by a single radiologist. Results The intra‐ and inter‐observer intraclass correlation coefficients (ICCs) of the CT method were higher than those of the radiographic method in normal beagle dogs. The intra‐observer ICC of the CT method before and after TPLO was generally higher than that of the radiographic method in the cadaver. However, no significant difference was noted in the evaluation of the intended postoperative TPA according to the preoperative planning method. Conclusions The intra‐ and inter‐observer ICCs allowed for easy identification of landmarks required to consistently determine the TPA in the preoperative planning of TPLO based on CT images

A genetic library screen for signaling proteins that interact with phosphorylated T cell costimulatory receptors

Abstract In the past decade, the fundamental importance and therapeutic potential of costimulatory signals for lymphocyte activation have spurred a large amount of work in immunology, infection, cancer, autoimmune diseases, etc. However, the mechanisms behind T cell costimulation remain unclear, partly due to the lack of suitable techniques. There is an urgent need for functional genomic research to develop comprehensive approaches to direct identification of protein-protein interactions that are dependent on the posttranslational modification of one component of the complex, particularly in the field of T cell immunology. Using inducible costimulator (ICOS) as a model, we failed to find any proteins that associated with the cytoplasmic tail of ICOS by the yeast two-hybrid approach. Therefore, we have developed a new yeast three-hybrid system that facilitates the rapid screening of cDNA libraries to find signaling molecules that interact with phosphorylated T cell costimulatory receptors. We demonstrate the utility of this technique to detect the interaction between ICOS and the p85 regulatory subunit of phosphatidylinositol 3-kinase (PI3K). The p85 unit of PI3K is the only signaling molecule identified so far that interacts with ICOS. This system may be of great help in dissecting the mechanisms of T cell costimulation and could be applied to other receptors. © 2006 Elsevier Inc. All rights reserved. Keywords: Functional genomics; Genetic screening; T lymphocytes; Costimulation; Phosphorylation; Inducible costimulator; Phosphatidylinositol 3-kinase It is now clear that T cell activation is initiated by the engagement of the antigen receptor and that the response that follows is regulated and shaped by other molecules collectively known as costimulators. The prototypical costimulatory receptor is CD28, which upon interaction with B7-1 or B7-2 provides signals that are required for optimal activation. The CD28 homolog CTLA-4, which also binds B7-1 and B7-2, attenuates T cell responses A central question in the study of T cell costimulatory receptor-mediated signaling pathways is to determine what other proteins interact with them. Many approaches have been taken to identify protein-protein interactions. One approach is the yeast two-hybrid syste