Contribution of co-contraction to arm impedance in the free planar movement / 医用生物力学

Objective Impedance control plays an important role in stability.This paper intends to explore such mechanism through modeling human reaching movement.Method Implemented with revised model,we ap-ply optimal control theory to neuro-muscle-skeleton model to calculate the stiffness ellipses.Result Com-pared with the original model and experimental figures,the model we proposed could overcome the shortage of monotonous changing of the original one and fit the data better.Conclusions So that this paper concludes that co-contraction contributes to impedance control even during free upper limb planar movement.

Contribution of co-contraction to arm impedance in the free planar movement / 医用生物力学

Objective Impedance control plays an important role in stability.This paper intends to explore such mechanism through modeling human reaching movement.Method Implemented with revised model,we ap-ply optimal control theory to neuro-muscle-skeleton model to calculate the stiffness ellipses.Result Com-pared with the original model and experimental figures,the model we proposed could overcome the shortage of monotonous changing of the original one and fit the data better.Conclusions So that this paper concludes that co-contraction contributes to impedance control even during free upper limb planar movement.

Reconstruction of large limb bone defects with a double-barrel free vascularized fibular graft / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>The use of a free, vascularized fibular graft is an important technique for the reconstruction of large defects in long bones. The technique has many advantages in strong, tubular bones; a more reliable vascular anatomy with a large vascular diameter and long pedicle is used, minimizing donor-site morbidity. Due to limitations in both fibular anatomy and mechanics, they cannot effectively be used to treat large limb bone defects due to their volume and strength.</p><p><b>METHODS</b>From 1990 to 2001, 16 clinical cases of large bone defects were treated using vascularized double-barrel fibular grafts. Patients were evaluated for an average of 10 months after surgery.</p><p><b>RESULTS</b>All the patients achieved bony union; the average bone union took 10 months post surgery, and no stress fractures occurred. Compared with single fibular grafts, the vascularized double-barrel fibular grafts greatly facilitate bony union and are associated with fewer complications, suggesting that the vascularized double-barrel fibular graft is a valuable procedure for the correction of large bone defects in large, long bones in addition to enhancing bone intensity.</p><p><b>CONCLUSIONS</b>The vascularized double-barrel fibular graft is superior to the single fibular graft in stimulating osteogenous activity and biological mechanics for the correction of very large bone defects in large, long bones. Free vascularized folded double-barrel fibular grafts can not only fill up large bone defects, but also improve the intensity margin. Therefore, this study also widens its application and enlarges the treatment targets. However, in the case of bone deformability, special attention should be paid to bone fixation and protection of donor and recipient sites.</p>

Inducing vascular smooth muscle cell proliferation by insulin involves in phosphatidylinositol 3-kinase and ERK1/2 / 中国病理生理杂志

AIM:To investigate the effect of insulin on vascular smooth muscle cells (VSMCs) proliferation and to evaluate the intracellular signaling pathways involved.METHODS:VSMCs separated from Sprague-Dawley rats were used in this study. The proliferation of VSMCs induced by insulin was assayed by [3H]-thymidin incorporation. The protein expression and activity of p-ERK1/2 were determined by immunblot and [?-32P]ATP incorporation.RESULTS:Insulin induced cell proliferation in a concentration-dependent manner. The proliferative effect of insulin on VSMCs was inhibited partly by LY294002 (48.8%),an inhibitor of PI-3 kinase,and the ERK1/2 inhibitor PD98059 (43.6%),respectively. Moreover,phosphorylation of ERK1/2 and activity of ERK1/2 induced by insulin were also inhibited partly by LY294002.CONCLUSION:PI-3 kinase and ERK1/2 are involved in insulin induced VSMCs proliferation.