Browsing by Subject "Ligation"

Now showing 1 - 3 of 3
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    Bracket, ligation, and misaligned straight wires effects on load systems during orthodontic sliding mechanics
    (2015-07) Hannah, Richard D.; Katona, Thomas R.
    Objective: The objectives of this study were to measure and compare the complete, not solely friction, load components (forces and moments) experienced by brackets as they slide along straight wires that are angled relative to the path of bracket travel. Materials and Methods: Three types of brackets (stainless steel mandibular canine and central incisor, and an all-ceramic mandibular canine) were ligated with stainless steel or elastomeric modules to 2 sizes of stainless steel wire (0.021” x 0.021” and 0.016” x 0.016”) at 0°, 1° and 2° bracket-wire misalignments. All 3 force and 3 moment components experienced by the brackets were measured as they slid along the wire. Results: Overall, all 36 permutations of the 3 brackets, 2 ligations, 2 wires and 3 alignments produced statistically different (predominantly P < .0001) load components on the bracket. Conclusions: The type of bracket, wire, ligation, and relatively small misalignments (1° and 2°) between bracket and wire affect all force and moment components applied to the bracket. Traditional friction-focused “pull through” studies miss the attendant effects on the other 5 load components.
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    The effects of bracket, wire conformation and size on the load systems during orthodontic sliding mechanics
    (2015-07) Mika, David E.; Katona, Thomas R.
    Objective: The purpose of this laboratory study was to compare all 6 load components (3 force and 3 moment) acting on 2 different stainless steel brackets as they slide along 3 sizes of stainless steel archwires with 3 different conformations. Materials and Methods: Brackets were attached to a load cell and elastomeric ligated to the wires. As the load cell was pulled along a precision track, the 6 load components (forces and moments in the 3 orthogonal coordinate system) acting on the bracket were recorded. ANOVA was applied to the data. Results: Overall, there were significant differences for all effects (bracket, wire size and wire configuration), for all outcomes (the loads), except the effect of bracket on the force of friction and one of the moment components. Conclusion: The results demonstrate that the force of friction associated with sliding mechanics should not be considered in isolation, because factors that affect it also affect the other 5 load components.
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    Nrf2 deficiency causes hepatocyte dedifferentiation and reduced albumin production in an experimental extrahepatic cholestasis model
    (PLOS, 2022-06-13) Wang, Guo-Ying; Garcia, Veronica; Lee, Joonyong; Yanum, Jennifer; Lin, Jingmei; Jiang, Huaizhou; Dai, Guoli; Biology, School of Science
    The transcription factor Nrf2 modulates the initiation and progression of a number of diseases including liver disorders. We evaluated whether Nrf2 mediates hepatic adaptive responses to cholestasis. Wild-type and Nrf2-null mice were subjected to bile duct ligation (BDL) or a sham operation. As cholestasis progressed to day 15 post-BDL, hepatocytes in the wild-type mice exhibited a tendency to dedifferentiate, indicated by the very weak expression of hepatic progenitor markers: CD133 and tumor necrosis factor-like weak induced apoptosis receptor (Fn14). During the same period, Nrf2 deficiency augmented this tendency, manifested by higher CD133 expression, earlier, stronger, and continuous induction of Fn14 expression, and markedly reduced albumin production. Remarkably, as cholestasis advanced to the late stage (40 days after BDL), hepatocytes in the wild-type mice exhibited a Fn14+ phenotype and strikingly upregulated the expression of deleted in malignant brain tumor 1 (DMBT1), a protein essential for epithelial differentiation during development. In contrast, at this stage, hepatocytes in the Nrf2-null mice entirely inhibited the upregulation of DMBT1 expression, displayed a strong CD133+/Fn14+ phenotype indicative of severe dedifferentiation, and persistently reduced albumin production. We revealed that Nrf2 maintains hepatocytes in the differentiated state potentially via the increased activity of the Nrf2/DMBT1 pathway during cholestasis.