Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P50583 (asymmetrical)
 12,197 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This in vitro study compared the retention and photoelastic stress patterns from two loading conditions, vertical (133.2 N, 30 pounds) and oblique at a 26 degrees angle (133.2 N, 30 pounds) for two prefabricated post systems. The post studied were: (1) Flexi-Post (a split-shank threaded post) and (2) C-Post (a carbon fibre bound in an epoxy resin, passive double taper tier post). Two groups with 10 specimens per group were subjected to retentive forces with a universal testing machine (MTS 810 Material Testing Machine). In addition, two photoelastic test blocks were prepared with simulated root canals for each post studied. After cementation the photoelastic blocks were photographed before vertical and oblique loading and after loading. One-way analysis of variance (ANOVA) for retention data revealed a highly significant difference (P<0.0001) between groups. The Flexi-Post had a statistically higher mean retention force of 1180.6 N (265.9 pounds), while the C-Post had a mean of 171.8 N (38.7 pounds). Photoelastic analysis indicated minimal stresses for both the Flexi-Post and C-Post in the unloaded state. The C-Post showed asymmetrical apically stress patterns, while loaded in both states. The multi-tiered system of the Flexi-Post clearly distributes stress symmetrically, while the C-Post distributes stresses asymmetrically. The symmetric, even stresses and statistically higher retentive strength for Flexi-Post are more favourable than the asymmetric, uneven stresses and relatively low retentive strength for the C-Post.
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PMID:Comparison of the retentive and photoelastic properties of two prefabricated endodontic post systems. 1039 81

Blount disease is a deformity of the knee as a result of abnormal mechanical forces known to influence the growth of the physis. Despite existing studies on mechanical forces on chondrocyte cultures or limited growth plate specimens, very little information characterizes the whole growth plate to asymmetrical loading. In this study, we evaluate the response of 5 ovine proximal tibial growth plates to asymmetrical mechanical loading. Fresh proximal tibia specimens were mounted, and compressive forces were applied via a servohydraulic test frame (MTS Systems Corporation, Minneapolis, Minn) machine at standardized locations while transducers recorded the displacement at different locations. With this method, we demonstrate that loading (cyclical or static) on 1 edge of the tibial surface results in compression through the physis under the site of pressure. In addition, we record statistically significant tensile displacement opposite the compressed side (P < 0.001); this effect diminished as loading cell moved central on the tibial surface. We further show that growth plate topography influences the amount of tension and compression observed. From this study, we conclude that asymmetrical loading (such as that observed in Blount disease) may lead to compression (which retards growth) but also develops tension on the convex side (which may be a mechanism to increase deformity via Depelch phenomenon). The relationship of physeal architecture (more undulations-less physeal strain) may explain why greater deformity is observed on the tibial side of the knee in adolescent Blount disease than on the femoral side.
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PMID:Mechanical behavior of the lamb growth plate in response to asymmetrical loading: a model for Blount disease. 1758 54