ABSTRACT
BACKGROUND: Sagittal imbalance makes significant effect on spinal biomechanics, and choosing osteotomy for ankylosing spondylitis depends on its biomechanics characteristics. OBJECTIVE: To establish a three-dimensional (3D) finite element model of kyphosis in ankylosing spondylitis treated by osteotomy on software, and to analyze its biomechanical properties, thus providing theoretical basis for clinical practice. METHODS: A 3D finite element model of kyphosis in ankylosing spondylitis was established based on CT data, and the predetermined angle of the osteotomy at L2was measured. Afterwards, vertebral column decancellation and vertebral column resection were stimulated, and then the biomechanical parameters were analyzed. RESULTS AND CONCLUSION: (1) The 3D finite element models of kyphosis in ankylosing spondylitis treated by vertebral column decancellation or vertebral column resection at L2were established successfully. (2) Finite element analysis on Ansys workbench 15.0 showed that the vertebral column decancellation (948 874, 1 564 477 nodes) and vertebral column resection (931 969, 1 548 812 nodes) were meshed and analyzed by 10-node tetrahedron solid element. (3) After loaded, the stress values of the vertebral column decancellation were higher than those of vertebral column resection; the equivalent stress on the screw was 40.946, 67.26, 493.64, 304.05, 75.359, and 146.31 MPa; the equivalent stress on the titanium rob was 391.01 MPa. (4) These results suggest that both two methods can reconstruct the sagittal balance, but vertebral column decancellation exhibits significantly higher stress values. Indeed, the incidence of internal fixation failure and complications in vertebral column decancellation is higher than that in vertebral column resection at the same segment and angle.
ABSTRACT
BACKGROUND: Kyphosis in ankylosing spondylitis is a kind of spinal sagittal imbalance; due to center of gravity displaced and complicated biomechanical properties of the spine, the spinal biomechanics after kyphosis correction is little reported. OBJECTIVE: To establish a three-dimensional finite element model of the spine after osteotomy for kyphosis. METHODS: A three-dimensional finite element model of kyphosis in ankylosing spondylitis was established, simulating three kinds of osteotomy orthopedic programs (osteotomy angle in 20°, 30° and 40°), and the orthopedic effect and biomechanics were analyzed.RESULTS AND CONCLUSION: (1) The three-dimensional finite element model of finite element model of kyphosis in ankylosing spondylitis was established successfully, and simulated three kinds of osteotomy orthopedic programs at the angles of 20°, 30°, and 40°. (2) The best osteotomy angle was 30°, the stress distribution was less, and the stress on the T12, L1, L2, L4, L5, S1and rod was 7.346 1, 11.952, 72.783, 81.368, 28.144, 41.114, and 109.69 MPa, respectively. (3) Under 30°osteotomy angle, the postoperative Cobb angle is 1.4°, which not only obtains better orthopedic effect, but also reduces the incidence of complications caused by stress concentration.
ABSTRACT
OBJECTIVE: To observe the effects of lappaconitine sulfate on proliferation, cycle and apoptosis of human cerical neoplasm Hela cells and its possible mechanism. METHODS: Cell Counting Kit-8 (CCK-8) was adopted to observe the inhibitory effects of lappaconitine sulfate on the proliferation of Hela cells and calculated its half maximal inhibitory concentration (IC50). The technology of flow cytometry, propidium iodide (PI) single stained method and Annexin-V-FITC/PI double stained method were employed to measure the cell cycle and apoptosis of Hela cells after lappaconitine sulfate treatment. RESULTS: Lappaconitine sulfate could inhibit the proliferation of human cerical neoplasm Hela cells in vitro, and the inhibition presented obvious dose-effect relationship (r=0.990 5, P<0.01). The IC50 of lappaconitine sulfate on Hela cells was 0.421 mg·mL-1. After dealt with lappaconitine sulfate, Hela cells indicated remarkable cell cycle arrest at G0/G1 phase, and the apoptotic ratio was gradually increased with the concentration of lappaconitine sulfate. CONCLUSION: Lappaconitine sulfate could inhibit the growth of human cerical neoplasm Hela cells, change the distribution of cell cycles and induce their apoptosis.
ABSTRACT
OBJECTIVE: To prepare lappaconitine (LA)-loaded chitosan/sodium β-glycerophosphate (CS/β-GP) thermosensitive hydrogels and investigate its phase transition mechanism of gel formation process and release properties in vitro. METHODS: The injectable CS/β-GP thermosensitive hydrogels were prepared with biodegradable CS as carrier material and β-GP as coagulation accelerator.The release behavior in vitro was studied by dynamic dialysis, and the phase transition mechanism of gel formation process was further investigated by rheologieal method. RESULTS: The optimized process condition was as follows;the concentration of β-GP and CS was 560 and 22 mg·mL-1, respectively, CS was dissolved by 0.1 mol·L-1 HOAc, and the valume ratio of CS to β-GP was 8.75:1.25 (V/V), the gelation time of CS/β-GP thermosensitive hydrogels with volume ratio of 8.75:1.25 (V/V) at 37℃ was 5 min 38 s.The in vitro release study showed that these injectable CS/β-GP thermosensitive hydrogels had sustained release effect for LA, and the release behavior could be well described by the Higuchi model and Korsmeyer-Peppas model.The mechanism of LA releasing from CS/β-GP thermosensitive hydrogels was attributed to drug dissolution and diffusion.Rheologieal studies showed that the CS/β-GP thermosensitive hydrogels belonged to thixotropic system and exhibited non-Newtonian and shear-thinning fluid behavior as well as "solid-like" gelatin behavior. CONCLUSION: LA-Loaded CS/β-GP injectable thermosensitive hydrogels with good elasticity and gel strength properties are prepared successfully, and they show sustained release effect of LA in vitro.
ABSTRACT
OBJECTIVE: To prepare lappaconitine (LA)-loaded polylactic acid (PLA) nanoparticles (LA/PLA NPs) and investigate its release properties in vitro. METHODS: LA/PLA NPs were prepared by optimized emulsion-solvent evaporation method with biodegradable PLA as carrier material and polyvinyl alcohol (PVA) as emulsifier. The entrapment efficiency and drug loading rate of LA were used as the main evaluation indexes to optimize the preparation process by orthogonal design method. The mean particle size was measured by laser particle size analyzer; the morphology of LA/PLA NPs was observed by atomic force microscope; the in vitro release behavior was studied by dynamic dialysis. RESULTS: The optimized LA/PLA NPs were spherical. The mean particle size was (429±9.19) nm, the entrapment efficiency and drug loading rate were (86.34±2.15)% and (45.85±1.34)%, respectively. The in vitro release study showed that the LA/PLA NPs could provide a continuous release of LA for 15 d. CONCLUSION: LA/PLA NPs with high entrapment efficiency and drug loading rate are prepared successfully, and show sustained release effect for LA in vitro.