ABSTRACT
BACKGROUND:Displacement of the distal fracture fragment is one of the most important facts that lead to cubitus varus fol owing pediatric supracondylar humeral fracture. Mainstream technique emphasized the restoration of posterior-ulnar deviation of the distal fragment. However, there is an absence of supportive evidences from biomechanical studies. OBJECTIVE:To establish models of extension-ulnar type of supracondylar humeral fracture and investigate the mechanical stability of reduced fracture with residual displacements within functional restoration standard, so as to provide mechanic evidences supporting the empirical rule of manipulative reduction-“better anterior than posterior, better radial than ulnar”. METHODS:The fresh cadaveric bone of right upper extremity from a 7-year-old child was scanned using CT. Models of supracondylar humeral fracture differing in contact area of the fracture site and displacement direction of the distal fragment were established and underwent loading tests. Stress in both anterior and posterior margin of the fracture site and Baumann angle were recorded, and data were analyzed and compared. RESULTS AND CONCLUSION:In comparison of stress in the posterior margin, the value was significantly greater in the posteromedial-displacement group than the others. Stress value in fracture with 75%contact area was significantly greater than the other three groups. In comparison of stress in the anterior margin, a significantly greater value was obtained in the posteromedial-displaced group. Stress value in fracture with 85%contact area was significantly greater. When comparing stress in posterior margin and anterior margin, the absolute increment of stress value was greater in posterior displacement group than in anterior displacement group. Baumann angle increased significantly when fragment displaced medial y. Above findings indicated that displacement direction altered the location of stress concentration. Stress augmentation was greater in posterior displacement group. Stress in related area significantly increased constantly when contact area of the fracture site reduced. Baumann changed obviously when fragment displaced medial y. The results preliminarily verify the hypothesis that displacement of the distal fragment was the main contributor to cubitus varus fol owing supracondylar humeral fracture. These findings provided certain evidences supporting the empirical rule“better anterior than posterior, better radial and ulnar”.
ABSTRACT
Objective To observe the influence of several kinase pathways such as extracellular signal-regulated kinase ( ERK) , and mitogen-activated protein kinase p38 ( p38MAPK) on nuclear factor erythroid 2-related factor 2 (Nrf2) pathway activated by Fructus Schisandrae extracts (FSE) . Methods HepG2 cells were treated by FSE for 24 hours after pretreatment with protein kinase inhibitors for 2 hours. The mRNA expression levels of Nrf2 and downstream target genes heme oxygenase-1 (HO-1), NAD (P) H quinine oxidoreductase 1(NQO1), P-glycoprotein ( P-gp) and multidrug resistance-associated protein 2 ( MRP2) were detected by real-time polymerase chain reaction ( RT-PCR) , and their protein expression levels and Nrf2 nuclear translocation were measured by Western blotting method. Results RT-PCR results showed that the mRNA expression levels of HO-1, NQO1, P-gp and MRP2 activated by FSE in HepG2 cells were inhibited by PD98059, SB203580 and Rottlerin, and the mRNA expression of Nrf2 was suppressed only by SB203580 and Rottlerin. Western blotting results showed that the mRNA expression levels of HO-1 and P-gp activated by SCE in HepG2 cells were inhibited by PD98059, SB203580 and Rottlerin. In addition, the protein expression of Nrf2 in HepG2 cytoplasm was increased by the above three inhibitors, and nuclear translocation of Nrf2 was inhibited by PD98059 and SB203580. Conclusion The mechanism of FSE activating Nrf2 pathway may be associated with the increase of Nrf2 nuclear translocation through the direct phosphorylation of Nrf2 induced by ERK and p38MAPK.