ABSTRACT
AIM To study the improvement of quercetin on Pseudomonas aeruginosa-induced lung infection in rats.METHODS Forty SPF SD rats were randomly divided into five groups,eight rats in each group:normal group,P.aeruginosa infection group,quercetin group,levofloxacin group,levofloxacin combined with quercetin group (combined group),the rats were anesthetized and then injected with P.aeruginosa in bronchus.The pathological changes of lung tissue in rats were observed,the contents of IL-4 and IFN-γcytokines,changes of transcription factors T-bet and Gata-3 in lung tissue were detected,and then semi-quantitative RT-PCR was used for the detection of IL-4,IFN-γ,T-bet and Gata-3 mRNA expressions.RESULTS The content of IL-4,levels of IL-4 and Gata-3 mRNA in lung tissue in the quercetin group,the levofloxacin group and the combined group were lower than those in the P.aeruginosa infection group,but the opposite was true in the levels of IFN-γ and T-bet mRNA.CONCLUSION Quercetin and levofloxacin can induce the differentiation from type Th2 to type Th1 for rat organism,but there is no synergistic effect between them.
ABSTRACT
AIM To study the improvement of quercetin on Pseudomonas aeruginosa-induced lung infection in rats.METHODS Forty SPF SD rats were randomly divided into five groups,eight rats in each group:normal group,P.aeruginosa infection group,quercetin group,levofloxacin group,levofloxacin combined with quercetin group (combined group),the rats were anesthetized and then injected with P.aeruginosa in bronchus.The pathological changes of lung tissue in rats were observed,the contents of IL-4 and IFN-γcytokines,changes of transcription factors T-bet and Gata-3 in lung tissue were detected,and then semi-quantitative RT-PCR was used for the detection of IL-4,IFN-γ,T-bet and Gata-3 mRNA expressions.RESULTS The content of IL-4,levels of IL-4 and Gata-3 mRNA in lung tissue in the quercetin group,the levofloxacin group and the combined group were lower than those in the P.aeruginosa infection group,but the opposite was true in the levels of IFN-γ and T-bet mRNA.CONCLUSION Quercetin and levofloxacin can induce the differentiation from type Th2 to type Th1 for rat organism,but there is no synergistic effect between them.
ABSTRACT
Objective To investigate the edge contact behavior of conformal spherical hip joint replacements under the given dynamic contact displacement condition. Methods Based on the developed spherical-grid-data model, the contact behavior and corresponding edge contact behavior of a typical metal-on-metal hip joint replacement was simulated under the increasing displacement between the acetabular cup and femoral head. Results It was found from the obtained results that the vertical and horizontal component of the support force due to contact pressure increased with the dynamic contact displacement increasing. The vertical component of support force for the edge contact showed a slower variation tendency than that for the non edge contact, while the corresponding horizontal component of support force increased more significantly with the dynamic displacement. In addition, the corresponding contact pressure distributions and the contact areas of hip joint replacements for edge contact and non-edge contact were different. Conclusions The significant edge contact behavior of hip joint replacements with bigger cup inclination angle occurrs with the increasing displacement of femoral head to the acetabular cup, which will cause the sliding between contact surfaces and additional wear since the horizontal support force increases. This provides a reference for the wear assessment and manufacturing of hip joint replacements.
ABSTRACT
Objective To develop a wear prediction model for hard-on-hard hip joint replacement under the condition of complex dynamic loading and time-dependent motion, and to apply it to the study on wear prediction of the typical metal-on-metal hip joint replacement in the complicated three-dimensional (3D) physiological motion condition. Methods The finite element model for contact mechanics was established and the fixed-tracked method was adopted to make the dynamic wear reappear on the bearing surface of artificial hip joint with 3D Euler transformation, and the data communication about the corresponding contact and wear for simulation was also made. Results The wear prediction test showed that the spherical bearing geometry of the artificial hip joint gradually became the non-spherical form due to the wear with time; meanwhile, the corresponding contact area was increased, the distribution of the contact pressure tended to be flattened, and the maximum contact pressure was decreased. Conclusions The wear prediction model developed here for metal-on-metal hip joint replacements with bilateral bearing surfaces under the condition of complex dynamic loading and motion could be used to carry out simulation test for the wear prediction of metal-on-metal artificial joint, which provides a new method to understand the wear mechanism of hip joint replacement.
ABSTRACT
Objective To study the contact mechanics of metal-on-metal hip joint replacements under different walking conditions, particularly for the edge contact behavior between the cup and the head of the bearing due to large range movement. Methods The finite element model of a typical hip joint replacement with conformal spherical bearing was established to simulate the edge contact of hip joint replacement under the given cup inclination angles and vertical loads. Results The maximum contact pressure decreased slightly and the contact area increased when the cup inclination angles increased within the range of 0°~60°. When the cup inclination angles were more than 80°, the corresponding contact area moved to the cup edge, the maximum contact pressure and distribution range increased, but the position of the maximum contact pressure moved from the initial contact point to the new point with 6°~9° in the direction of the increasing cup inclination angle to balance the corresponding contact pressure distribution and the loaded human weight. Conclusions Different edge contact behavior of hip joint replacements tends to occur due to the bigger cup inclination angle. Therefore, much attention should be paid to the problem of edge contact for both the clinical surgery and the manufacturing of hip joint replacements.