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A continuous attractor of recurrent neural network is a connected set of stable equilibrium points. It's widely used to interpret a lot of brain activities. A large number of literatures have studied discrete attractors and single continuous attractor. In this paper, the coexisting continuous attractors for nonlinear neural networks is studied and the coexisting conditions of two continuous attractors for network with and without external input in two-dimensional space are obtained by analysing the eigenvalues of the matrix. Finally, all the results are verified by simulation. [ABSTRACT FROM AUTHOR]

Objective To determine the effect of long-term use of methylprednisolone on bone biomechanics of rats. Methods Thirty-eight 3-month-old female SD rats were chosen. They were randomly divided into basal control group (B group, 8 rats were sacrificed at the beginning of the experiment as baseline), normal control group ( C group, 10 rats were given intraperitoneal injection of 75mg/kg normal saline), low dose methylprednisolone group(L group, 10 rats were given intraperitoneal injection of 50 mg/kg methylprednisolone), and high dose methylprednisolone groug (H group, 10 rats were given intraperitoneal injection of 75 mg/kg methylprednisolone). Methylprednisolone was given in L group and H group for 3 days, and stopped for a week. Then the intraperitoneal injection was given once a week according to the plan. After 24 weeks of the treatment, the femurs and the lumbar spine L3 were collected for biomechanical experiment. Results (1) Compared to that in C group, the body weight in L group and H group decreased obviously after the experiment (P <0. 05). (2) Compared to those in C group, structural mechanical parameters (load and rigidity) and material mechanical parameters (breaking strength and modulus of rigidity) of the femurs in L group and H group significantly decreased (P <0. 05). (3) Compared to those in C group, structural mechanical parameters (load and rigidity) and material mechanical parameters (breaking strength and modulus of rigidity) of the L3 in L group and H group significantly decreased (P < 0. 05 ). Conclusion The long-term use of methylprednisolone, regardless of dose, results in the decrease of bone quality of the femur and the lumbar spine of rats. [ABSTRACT FROM AUTHOR]

Objective To investigate the preventive effect of stanozolol on retinoic acid-induced bone lesion in rats using bone mineral density (BMD), biomechanics, and bone histomorphometry methods. Methods Twenty-four 4-month-old virgin female Sprague-Dawley rats were randomly divided into control group, retinoic acid (RA) group, and stanozolol group. Rats in control group were given vehicle. Rats in RA groups were given RA of 70 mg* kg 1 ⋅ d-1. Rats in stanozolol group were given RA of 70 mg ⋅ kg-1 ⋅ d-1 and stanozolol of 0. 5 mg ⋅ kg-1 ⋅ d-1. All the rats were oral gavaged at 5 mL⋅ kg-1 for 28 days. At the experimental endpoint, bone mineral density (BMD) of the right femur was examined, and biomechanical properties and bone histomorphometric parameters of the proximal tibial metaphysis ( PTM) and the tibial shaft (Tx) were measured. Results Compared to those in control group, BMD decreased by 10. 2%, and biomechanical properties including elastic load, maximum load, break load, rigid coefficient, and bending energy decreased by 39. 1%, 32. 9%, 36. 4%, 40. 2%, 38. 0% in femur in RA group, respectively (P <0.01). Compared to those in control group, the static parameters including total tissue area, trabecular area, and trabecular perimeter decreased by 31. 6%, 40. 0%, and 36. 2% (P < 0. 01), and the dynamic parameters including percent labeled perimeter (% L. Pm), bone formation rate (BFR/TV, BFR/BV, and BFR/BS) decreased by 57. 1%, 69. 9%, 62.0%, and 65. 8%, respectively, in PTM in RA group (P < 0. 01). Compared to those in control group, the static parameters (the total tissue area and cortical area) and the dynamic parameters of periosteum of Tx significantly decreased, while the dynamic parameters of endosteum of Tx significantly increased in RA group. Compared to those in RA group, the elastic load, rigid coefficient, and bending-energy increased by 22. 2%, 22. 9%, and 17. 7%, respectively, in the femurs in stanozolol group. No significant changes of BMD and histomorphometric parameters in PTM and Tx were found in stanozolol group. Conclusion Stanozolol can partially relieve bone damage induced by RA in rats. [ABSTRACT FROM AUTHOR]

Aim: To investigate the bone-protective effects of salvianolate (Sal), a total polyphenol from Radix Salviae miltiorrhizae, on bone tissue in the spontaneous lupus-prone mouse model, B6.MRL-Fas (lpr) /J, undergoing glucocorticoid (GC) treatment., Methods: Fifteen-week-old female B6.MRL-Fas (lpr) /J mice were administered either a daily dose of saline (lupus group), prednisone 6 mg/kg (GC group), Sal 60 mg/kg (Sal group); or GC plus Sal (GC + Sal group) for a duration of 12 weeks. Age-matched female C57BL/6J wild-type (WT) mice were used for control. Micro-computed tomography assessments, bone histomorphometry analysis, bone biomechanical test, immunohistochemistry and immunoblotting analysis for bone markers, and renal histology analysis were performed to support our research endeavor., Results: Lupus mice developed a marked bone loss and deterioration of mechanical properties of bone due to an increase in bone resorption rather than suppression of bone formation. GC treatment strongly inhibited bone formation in lupus mice. Sal treatment significantly attenuated osteogenic inhibition, and also suppressed hyperactive bone resorption, which recovered the bone mass and mechanical properties of bone in both the untreated and GC-treated lupus mice., Conclusion: The data support further preclinical investigation of Sal as a potential therapeutic strategy for the treatment of systemic lupus erythematosus-related bone loss.

This investigation was directed to the effects of DanShenGuBao on biomechanical properties and bone mineral density (BMD) of femur induced by retinoic acid (RA) in rats. Forty 4-month-old virgin female Sprague-Dawley rats were randomly divided into 5 groups(8 rats each) control group, RA group and different doses of DanShenGuBao groups. Rats in control group were given vehicle, rats in other four groups were given RA at 70 mg x kg(-1) x d(-1) in the morning and given different drugs in the afternoon at the same time. Rats in RA group were given vehicle, rats in other groups were given different doses of DanShenGuBao which contained 10 mg x kg(-1) x d(-1), 5 mg x kg(-1) x d(-1), 2.5 mg x kg(-1) x d(-1) tanshinol, respectively. All of rats were treated at 5 ml x kg(-1) by oral gavaged for 28 days. In preparation for the determination of dynamic changes in bone tissues, all rats were given subcutaneous injections of 30 mg x kg(-1) tetracycline on the 14th, 13th day and 5 mg x kg(-1) calcein on the 4th, 3rd day before death. At the experimental endpoint, the rats were sacrificed by cardiac puncture under sodium pentobarbital anesthesia. Physical parameters, BMD and biomechanical properties of femur were assessed. Compared with those in control group, the physical parameters (cross-sectional diameter, wet and dry weight), BMD and biomechanical properties (max-load, elasticity-load, break-strain, rigid coefficient and bending-energe) were significantly decreased in RA group. Compared with that in RA group, the BMD of femur was increased significantly in medium and high dose of DanShenGuBao group, but there was no significant change in physical parameters and biomechanical properties of femur. RA could decrease the physical parameters, BMD and biomechanical properties of femur. DanShenGuBao could increase BMD, but it was found with no obvious effect on physical parameters and biomechanical properties.