Ludlow J.B.,North Carolina Oral Health Institute |
Timothy R.,University of North Carolina at Chapel Hill |
Walker C.,University of Missouri |
Hunter R.,Private Practice |
And 3 more authors.
Dentomaxillofacial Radiology | Year: 2015
Objectives: This article analyses dose measurement and effective dose estimation of dental CBCT examinations. Challenges to accurate calculation of dose are discussed and the use of dose-height product (DHP) as an alternative to dose-area product (DAP) is explored.Methods: The English literature on effective dose was reviewed. Data from these studies together with additional data for nine CBCT units were analysed. Descriptive statistics, ANOVA and paired analysis are used to characterize the data.Results: PubMed and EMBASE searches yielded 519 and 743 publications, respectively, which were reduced to 20 following review. Reported adult effective doses for any protocol ranged from 46 to 1073 μSv for large fields of view (FOVs), 9-560 μSv for medium FOVs and 5-652 μSv for small FOVs. Child effective doses from any protocol ranged from 13 to 769 μSv for large or medium FOVs and 7-521 μSv for small FOVs. Effective doses from standard or default exposure protocols were available for 167 adult and 52 child exposures. Mean adult effective doses grouped by FOV size were 212 μSv (large), 177 μSv (medium) and 84 μSv (small). Mean child doses were 175 μSv (combined large and medium) and 103 μSv (small). Large differences were seen between different CBCT units. Additional low-dose and highdefinition protocols available for many units extend the range of doses. DHP was found to reduce average absolute error for calculation of dose by 45% in comparison with DAP.Conclusions: Large exposure ranges make CBCT doses difficult to generalize. Use of DHP as a metric for estimating effective dose warrants further investigation. © 2015 The Authors.
Perepelyuk M.,University of Pennsylvania |
Terajima M.,North Carolina Oral Health Institute |
Wang A.Y.,University of Virginia |
Georges P.C.,University of Pennsylvania |
And 3 more authors.
American Journal of Physiology - Gastrointestinal and Liver Physiology | Year: 2013
Liver fibrosis is characterized by excessive deposition of extracellular matrix proteins by myofibroblasts derived from hepatic stellate cells and portal fibroblasts. Activation of these precursors to myofibroblasts requires matrix stiffness, which results in part from increased collagen crosslinking mediated by lysyl oxidase (LOX) family proteins. The aims of this study were to characterize the mechanical changes of early fibrosis, to identify the cells responsible for LOX production in early injury, and to determine which cells in normal liver produce collagens and elastins, which serve as substrates for LOXs early after injury. Hepatocytes and liver nonparenchymal cells were isolated from normal and early-injured liver and examined immediately for expression of LOXs and matrix proteins. We found that stellate cells and portal fibroblasts were the major cellular sources of fibrillar collagens and LOXs in normal liver and early after injury (1 day after bile duct ligation and 2 and 7 days after CCl4 injury). Activity assays using stellate cells and portal fibroblasts in culture demonstrated significant increases in LOX family enzymatic activity as cells became myofibroblastic. LOX family-mediated deoxypyridinoline and pyridinoline cross-links increased after CCl4-mediated injury. There was a significant association between liver stiffness (as quantified by the shear storage modulus G') and deoxypyridinoline levels; increased deoxypyridinoline levels were also coincident with significantly increased elastic resistance to large strain deformations, consistent with increased cross-linking of the extracellular matrix. These data suggest a model in which the liver is primed to respond quickly to injury, activating potential mechanical feed-forward mechanisms. © 2013 the American Physiological Society.
Mochida Y.,Boston University |
Mochida Y.,North Carolina Oral Health Institute |
Kaku M.,North Carolina Oral Health Institute |
Kaku M.,Niigata University |
And 4 more authors.
Biochemical and Biophysical Research Communications | Year: 2011
Recently, significant attention has been drawn to the biology of small leucine-rich repeat proteoglycans (SLRPs) due to their multiple functionalities in various cell types and tissues. Here, we characterize a novel SLRP member, " Podocan-like (Podnl) protein" identified by a bioinformatics approach. The Podnl protein has a signal peptide, a unique cysteine-rich N-terminal cluster, 21 leucine-rich repeat (LRR) motifs, and one putative N-glycosylation site. This protein is structurally similar to podocan in SLRPs. The gene was highly expressed in mineralized tissues and in osteoblastic cells and the high expression level was observed at and after matrix mineralization in vitro. Podnl was enriched in newly formed bones based on immunohistochemical analysis. When Podnl was transfected into osteoblastic cells, the protein with N-glycosylation was detected mainly in the cultured medium, indicating that Podnl is a secreted N-glycosylated protein. The endogenous Podnl protein was also present in bone matrix. These data provide a new insight into our understanding of the emerging SLRP functions in bone formation. © 2011 Elsevier Inc.