Is fixation of the medial malleolus necessary in unstable ankle fractures?

Introduction: It is unclear whether the medial malleolus in unstable bi- and tri- malleolar ankle fractures without medial talar displacement should be addressed surgically. This study reviews a fixation protocol for the medial malleolar component of unstable bi- or tri- malleolar ankle fractures.

Materials And Methods: Two hundred fifty-seven patients who sustained bi- (AO/OTA 44-B2) or tri- (AO/OTA 44-B3) malleolar ankle fractures between January 2005 and August 2019 at two Level 1 trauma centers were retrospectively identified.

Nuclear Medicine Scans in Total Joint Replacement.

»: A 3-phase bone scan is a potential first-line nuclear medicine study for pain after total joint arthroplasty (TJA) when there is concern for periprosthetic joint infection or aseptic loosening.

»: In patients who have a positive bone scintigraphy result and suspected infection of the joint, but where aspiration or other studies are inconclusive, labeled leukocyte scintigraphy with bone marrow imaging may be of benefit.

»: Magnetic resonance imaging (MRI), while not a nuclear medicine study, also shows promise and has the advantage of providing information about the soft tissues around a total joint replacement.

Platelet-rich plasma increases transforming growth factor-beta1 expression at graft-host interface following autologous osteochondral transplantation in a rabbit model.

Aim: To explore the effect of platelet-rich plasma on protein expression patterns of transforming growth factor-beta1 (TGF-β1) in cartilage following autologous osteochondral transplantation (AOT) in a rabbit knee cartilage defect model.

Methods: Twelve New Zealand white rabbits received bilateral AOT. In each rabbit, one knee was randomized to receive an autologous platelet rich plasma (PRP) injection and the contralateral knee received saline injection.

Low Level of Evidence and Methodologic Quality of Clinical Outcome Studies on Cartilage Repair of the Ankle.

Purpose: To examine the level of evidence and methodologic quality of studies reporting surgical treatments for osteochondral lesions of the ankle.

Methods: A search was performed using the PubMed/Medline, Embase, CINAHL (Cumulative Index to Nursing and Allied Health Literature), and Cochrane databases for all studies in which the primary objective was to report the outcome after surgical treatment of osteochondral lesions of the ankle. Studies reporting outcomes of microfracture, bone marrow stimulation, autologous osteochondral transplantation, osteochondral allograft transplantation, and autologous chondrocyte implantation were the focus of this analysis because they are most commonly reported in the literature.

Formation of covalently bonded polycyclic hydrocarbon ions by intracluster polymerization of ionized ethynylbenzene clusters.

Here we report a detailed study aimed at elucidating the mechanism of intracluster ionic polymerization following the electron impact ionization of van der Waals clusters of ethynylbenzene (C8H6)n generated by a supersonic beam expansion. The structures of the C16H12, C24H18, C32H24, C40H30, and C48H36 radical cations resulting from the intracluster ion-molecule addition reactions have been investigated using a combination of mass-selected ion dissociation and ion mobility measurements coupled with theoretical calculations. Noncovalent structures can be totally excluded primarily because the measured fragmentations cannot result from noncovalent structures, and partially because of the large difference between the measured collision cross sections and the calculated values corresponding to noncovalent ion-neutral complexes.

The ability of Sos1 to oligomerize the adaptor protein LAT is separable from its guanine nucleotide exchange activity in vivo.

The activation of the small guanosine triphosphatase Ras by the guanine nucleotide exchange factor (GEF) Sos1 (Son of Sevenless 1) is a central feature of many receptor-stimulated signaling pathways. In developing T cells (thymocytes), Sos1-dependent activation of extracellular signal-regulated kinase (ERK) is required to stimulate cellular proliferation and differentiation. We showed that in addition to its GEF activity, Sos1 acted as a scaffold to nucleate oligomerization of the T cell adaptor protein LAT (linker for activation of T cells) in vivo.

A phospholipase C-γ1-independent, RasGRP1-ERK-dependent pathway drives lymphoproliferative disease in linker for activation of T cells-Y136F mutant mice.

Mice expressing a germline mutation in the phospholipase C-γ1-binding site of linker for activation of T cells (LAT) show progressive lymphoproliferation and ultimately die at 4-6 mo age. The hyperactivated T cells in these mice show defective TCR-induced calcium flux but enhanced Ras/ERK activation, which is critical for disease progression. Despite the loss of LAT-dependent phospholipase C-γ1 binding and activation, genetic analysis revealed RasGRP1, and not Sos1 or Sos2, to be the major Ras guanine exchange factor responsible for ERK activation and the lymphoproliferative phenotype in these mice.

Deconstructing Ras signaling in the thymus.

Thymocytes must transit at least two distinct developmental checkpoints, governed by signals that emanate from either the pre-T cell receptor (pre-TCR) or the TCR to the small G protein Ras before emerging as functional T lymphocytes. Recent studies have shown a role for the Ras guanine exchange factor (RasGEF) Sos1 at the pre-TCR checkpoint. At the second checkpoint, the quality of signaling through the TCR is interrogated to ensure the production of an appropriate T cell repertoire.

Targeted Sos1 deletion reveals its critical role in early T-cell development.

Activation of the small G protein Ras is required for thymocyte differentiation. In thymocytes, Ras is activated by the Ras guanine exchange factors (RasGEFs) Sos1, Sos2, and RasGRP1. We report the development of a floxed allele of sos1 to assess the role of Sos1 during thymocyte development.