Browsing by Author "Jorgenson, Britta"

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    Cortical Porosity in Bone
    (2014-05-14) Jorgenson, Britta; Boyd, Steven
    Osteoporosis (porous bones) is a disease that is characterized by decreased bone strength and increased risk of fracture due to loss of bone strength from decreased bone mass and deterioration of bone micro-architecture. In particular, cortical porosity (CtPo) significantly impacts bone strength and has been associated with the progression of the disease and the occurrence of fracture. Very recently, it has become possible to assess CtPo in the appendicular skeleton in vivo through the use of high-resolution peripheral quantitative computed tomography (HR-pQCT). There are two approaches to assessing CtPo from HR-pQCT imaging data based on a threshold-based or a density-based approach. The performance of both methods was compared against gold-standard synchrotron radiation micro computed tomography (SRu CT) measurements. The threshold-based approach was found to be more highly correlated with true values of CtPo than a density-based approach. Improved CtPo measures may lead to better imaging diagnostics to detect and monitor osteoporosis.
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    p21−/− mice exhibit enhanced bone regeneration after injury
    (2017-11-09) Premnath, Priyatha; Jorgenson, Britta; Hess, Ricarda; Tailor, Pankaj; Louie, Dante; Taiani, Jaymi; Boyd, Steven; Krawetz, Roman
    Abstract Background p21(WAF1/CIP1/SDI1), a cyclin dependent kinase inhibitor has been shown to influence cell proliferation, differentiation and apoptosis; but more recently, p21 has been implicated in tissue repair. Studies on p21(−/−) knockout mice have demonstrated results that vary from complete regeneration and healing of tissue to attenuated healing. There have however been no studies that have evaluated the role of p21 inhibition in bone healing and remodeling. Methods The current study employs a burr-hole fracture model to investigate bone regeneration subsequent to an injury in a p21−/− mouse model. p21−/− and C57BL/6 mice were subjected to a burr-hole fracture on their proximal tibia, and their bony parameters were measured over 4 weeks via in vivo μCT scanning. Results p21−/− mice present with enhanced healing from week 1 through week 4. Differences in bone formation and resorption potential between the two mouse models are assessed via quantitative and functional assays. While the μCT analysis indicates that p21−/− mice have enhanced bone healing capabilities, it appears that the differences observed may not be due to the function of osteoblasts or osteoclasts. Furthermore, no differences were observed in the differentiation of progenitor cells (mesenchymal or monocytic) into osteoblasts or osteoclasts respectively. Conclusions Therefore, it remains unknown how p21 is regulating enhanced fracture repair and further studies are required to determine which cell type(s) are responsible for this regenerative phenotype.