Publications by authors named "Nathan A Wigner"

Patients who sustain orthopaedic trauma are at risk for developing deep venous thrombosis and symptomatic pulmonary emboli. The prevention of venous thromboembolism has moved to the forefront of patient safety initiatives, resulting in the formation of various guidelines to assist the practitioner. Recommendations for venous thromboembolism prophylaxis in the orthopaedic trauma patient exist, but there is insufficient evidence in the literature to make strong recommendations regarding type and duration of prophylaxis.

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Previous studies showed that loss of tumor necrosis factor α (TNFα) signaling delayed fracture healing by delaying chondrocyte apoptosis and cartilage resorption. Mechanistic studies showed that TNFα induced Fas expression within chondrocytes; however, the degree to which chondrocyte apoptosis is mediated by TNFα alone or dependent on the induction of Fas is unclear. This question was addressed by assessing fracture healing in Fas-deficient B6.

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Runx2 and Runx3 are known to be expressed in the growth plate during endochondral bone formation. Here we addressed the functional role of Runx3 as distinct from Runx2 by using two models of postnatal bone repair: fracture healing that proceeds by an endochondral process and marrow ablation that proceeds by only an intramembranous process. Both Runx2 and Runx3 mRNAs were differentially up regulated during fracture healing.

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The differentiation of osteoblasts from their precursors, mesenchymal stem cells, is an important component of bone homeostasis as well as fracture healing. The A2B adenosine receptor (A2BAR) is a Gα(s)/α(q)-protein-coupled receptor that signals via cAMP. cAMP-mediated signaling has been demonstrated to regulate the differentiation of mesenchymal stem cells (MSCs) into various skeletal tissue lineages.

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Whilst the majority of fractures heal normally, it is estimated that ∼10% of fractures exhibit some level of delayed or impaired healing. Although radiography is the primary diagnostic tool to assess the progression of fracture healing, radiographic features only qualitatively correlate with tissue level increases in mineral content and do not quantitatively measure underlying biological processes that are associated with the progression of healing. Specific metaloproteinases have been shown to be essential to processes of both angiogenesis and mineralised cartilage resorption and bone remodelling at different phases of fracture healing.

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Background: The acute-phase response (APR) is critical to the body's ability to successfully respond to injury. A murine model of closed unilateral femur fractures and bilateral femur fracture were used to study the effect of injury magnitude on this response.

Methods: Standardized unilateral femur fracture and bilateral femur fracture in mice were performed.

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Article Synopsis
  • The study aimed to understand how mechanical stimulation affects gene expression related to cartilage formation in young rats after a specific type of bone surgery.
  • Researchers used a microarray to analyze changes in messenger RNA expression over time in response to bending motions, finding that most of the 100 differentially expressed genes were up-regulated and linked to cartilage development.
  • The results showed that the glycosaminoglycan content in the stimulated tissues increased and matched that of normal cartilage by day 38, suggesting mechanical stimulation is important for proper cartilage formation post-surgery.
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  • Hypophosphatemia causes conditions like rickets and osteomalacia, leading to weaker bones and poor fracture healing due to impaired cellular processes.
  • In research with mice, phosphate deficiency before or after a femoral fracture led to significant healing issues, mainly affecting the differentiation of stem cells into cartilage-forming cells.
  • The study found that while initial cell recruitment was unaffected by low phosphate levels, their ability to differentiate properly was hindered, revealing the critical role of phosphate in bone repair beyond just mineralization.
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Fracture healing involves multiple stages of repair and coordinated actions of multiple cell types. Consequently, it may be possible to enhance healing through treatment strategies that target more than one repair process or cell type. The goal of this study was to determine the combined effects of recombinant human bone morphogenetic protein 7 (rhBMP-7) and parathyroid hormone (PTH(1-34)) on metaphyseal bone healing.

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Article Synopsis
  • - Studies indicate that systemic treatment with PTH (parathyroid hormone) improves bone repair rates in rodent models by enhancing the early stages of endochondral bone repair, specifically by increasing the recruitment and differentiation of chondrocytes.
  • - PTH treatment also resulted in elevated levels of canonical Wnt-signaling during various phases of fracture healing, suggesting that the effects of PTH are partially mediated through this signaling pathway.
  • - Research involved creating femoral fractures in mice and administering PTH or saline, with subsequent analysis showing significant increases in callus volume and structure in PTH-treated bones compared to controls, as confirmed by multiple imaging and molecular techniques.
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