Discrete element modeling and experimental study of biomechanical properties of cotton stalks in machine-harvested film-stalk mixtures.

To address the current problems of low accuracy and poor reliability of the discrete element model of cotton stalks, as well as the difficulty of guiding the design and optimization of the equipment through simulations, the discrete element modeling and physical-mechanical tests of cotton stalks in machine harvested film-stalk mixtures are carried out. The peak tensile force F j max , the peak pressure F y max , the peak bending force F w max , the peak shear force F j max , and the force-displacement (F-x) curves of cotton stalks are obtained from the physical tests. The discrete element model of double-layer cotton stalks based on the flat-joint model is established with the PFC 3 D software. The F y max is taken as the response value, and the microscopic parameters of the cotton stalk model are used as the test factors, then the Plackett-Burman test, the steepest climb test, and the Box-Behnken test are sequentially designed using Design-Expert software. The second-order regression model describing the relationship between the F y max and the microscopic parameters is established. The optimal parameter combinations of the microscopic parameters are obtained, and then they are utilized to construct the compression, bending, and shear models of cotton stalks and to carry out the validation tests. The results confirm that the established discrete element model could accurately characterize the biomechanical properties of cotton stalks and that the parameter calibration method is reasonable, which could provide a reference for the discrete element modeling of cotton stalks and other stalks, and also offer a theoretical basis for the research of the crushing and separation mechanism of the film-stalk mixtures and the development of the equipment.

Effect of Electromyographic Biofeedback Therapy on Muscle Strength Recovery in Children with Guillain-Barré Syndrome.

GBS, as an immune-mediated acute inflammatory peripheral neuropathy (Tan and Halpin et al.), with the characteristics of acute onset and rapid progression, is mainly manifested with damages in nerve root and peripheral nerve. The purpose of the study was to investigate the effect of electromyographic biofeedback therapy on muscle strength recovery in children with Guillain-Barré syndrome (GBS). A total of 62 GBS children patients admitted to our hospital from June 2014 to December 2018 were selected and divided into control group (n = 30) and experimental group (n = 32) according to the order of admission. The children patients in the control group received physical therapy combined with occupational therapy (PT + OT), while based on the treatment in the control group, the experimental group children patients were treated with electromyographic biofeedback therapy. After that, the recovery of nerve and muscle at different time points, muscle strength score, gross motor function measure (GMFM) score, and Barthel index (BI) score of the children patients before and after treatment were compared between the two groups. There were no significant differences in the recovery of nerve and muscle of the children patients between the two groups at T 0 and T 1 (P > 0.05), and the recovery of nerve and muscle of the children patients in the experimental group was significantly better than that in the control group at T 2, T 3, and T 4 (P < 0.001); the muscle strength score, GMFM score, and BI score of the children patients in the experimental group were significantly better than those in the control group after treatment (P < 0.001). The application of electromyographic biofeedback therapy for the treatment of GBS can effectively relieve clinical symptoms, promote rapid recovery, and improve treatment efficacy in children patients, which is worthy of application and promotion.

Alleviation of Oxidative Damage and Involvement of Nrf2-ARE Pathway in Mesodopaminergic System and Hippocampus of Status Epilepticus Rats Pretreated by Intranasal Pentoxifylline.

The current studies were aimed at evaluating the efficacy of intranasal pentoxifylline (Ptx) pretreatment in protecting mesodopaminergic system and hippocampus from oxidative damage of lithium-pilocarpine induced status epilepticus (SE) and the involvement of nuclear factor erythroid 2-related factor 2- (Nrf2-) antioxidant response elements pathway. Pentoxifylline was administered to rats intranasally or intraperitoneally 30 minutes before inducing SE. Our results showed the impaired visuospatial memory, the defected mesodopaminergic system, and the oxidative damage and the transient activation of Nrf2 in SE rats. The transient activation of Nrf2 in SE rats was enhanced by Ptx pretreatment, which was followed by the upregulation of heme oxygenase-1 and NAD(P)H:quinone oxidoreductase-1. Ptx pretreatment to SE rats significantly suppressed the epileptic seizures, decreased the levels of lipid peroxide and malondialdehyde, and elevated the ratio of reduced glutathione/oxidized glutathione. Compared with intraperitoneal injection, intranasal Ptx delivery completely restored the visuospatial memory and the activity of mesodopaminergic system in SE rats. Intranasal administration of Ptx may hopefully become a noninvasive, painless, and easily administered option for epileptic patients.

[Feasibility and clinical application of design about the hollowed titanium stick supporting the femoral head and preventing it from collapsing].

OBJECTIVE: To evaluate the feasibility and the clinical practicality of the design about the hollowed titanium stick supporting the femoral head and preventing it from collapsing. METHODS: From Jan.2003 to Jun.2007, 36 patients (46 hips) diagnosed as cystis degeneration of the femoral head were treated by surgical operation, including 20 males and 16 females with an average age of 40 years ranging from 18 to 56 years old, and the course of the disease was from 10 to 24 months (16 months on average). According to ARCO staging,there were 24 patients (34 hips) in NFH II, of which 11 hips were II a stage, 13 hips were II b stage and 10 hips were II c stage; there were 6 patients diagnosed as osteofibrous,4 patients as simple bone cyst and 2 patients as chondromyxoid fibroma. Under X-ray the percutaneous narrow core decompression and focus infection elimination were performed and supported the sclerotin under the cartilage with titanium stick. The patients were followed-up at the first, third, sixth, twelfth, twenty-fourth and thirty-sixth month after the operation. The clinical evaluation was done by X-ray and the indexes included stable, unstable and abortive. The data was analyzed by Fisher exact probility and the suviaval rate was analyzed by Kaplan-Meier suviaval curve using statistical soft ware SPSS13.5. RESULTS: There were no unstable or failure cases on each period from the 1st month to the 12th month after the operation, indicating that the supporting effect of the titanium stick was exact during 12 months after the operation. There were unstable and failure cases from the 12th month to the 24th month after the operation, which were mainly in stage NFH II c but the comparision of the stable rate in this period and 12 months after the operation had no obvious statistical differences (P>0.05) indicating that the supporting effect of the titanium stick was feasible during the stage. One of the unstable cases deteriorated and failed but there were no new unstable cases, both the stable rate and the unstable rate had no change and the failure rate rose on the 36th month after the operation. The compar- ision of the stable rate on each period after the operation had no obvious difference (P=0.197>0.05), which indicated that the supporting effect of the titanium stick was persistent. By the difference of the etiology the three-year survival rate of the relevant NFH II c pathological changes was the lowest-70% and the survival rate of the pathological changes induced by other etiological factors was 90.2%. CONCLUSION: The design about the hollowed titanium stick supporting the collapsed femoral head is feasible. Using the hollowed titanium stick to support the femoral head and prevent it from collapsing is pragmatic in the clinical and the effect is positive, however, when it comes to the NFH II c pathological changes, the choice should be made discreetly.

[Comparison of effect between vascularization osteogenesis and membrane guided osteogenesis in bone repair by tissue engineered bone with pedicled fascial flap packing autologous red bone marrow].

OBJECTIVE: To compare the effect between vascularization osteogenesis and membrane guided osteogenesis in the bone repair by the tissue engineered bone with pedicled fascial flap packing autologous red bone marrow (ARBM), so as to provide a reference for the bone defect repair in clinic. METHODS: The tissue engineered bone was constructed with ARBM and the osteoinductive absorbing recombinant human materials with recombinant human bone morphogenetic protein 2. Sixty New Zealand rabbits (aged 4-5 months, weighing 2.0-2.5 kg) were randomly divided into group A (n = 16), group B (n = 22), and group C (n = 22). The complete periosteum defect model of 1.5 cm in length was prepared in right ulnar bone, then the tissue engineered bone was implanted in the bone defect area in group A, the tissue engineered bone with free fascial flap in group B, and the tissue engineered bone with pedicled fascial flap in group C. At 4, 8, 12, and 16 weeks, the tissue of bone defect area was harvested from 4 rabbits of each group for the general, histological, and immunohistochemical staining observations; at 8, 12, and 16 weeks, 2 rabbits of groups B and C, respectively were selected to perform ink perfusion experiment by axillary artery. RESULTS: The general observation showed that the periosteum-like tissues formed in the fascial flap of groups B and C, chondroid tissues formed in group B, new bone formed in group C, and the fibrous and connective tissues in group A at 4 and 8 weeks; a few porosis was seen in group A, more new bone in group B, and bone stump formation in group C at 12 and 16 weeks. Histological observation showed that there were few new blood vessels and new bone trabeculae in groups A and B, while there were large amounts of new blood vessels and mature bone trabeculae in group C at 4 and 8 weeks. There were a few new blood vessels and new bone trabeculae in group A; more blood vessels, significantly increased mature trabeculae, and the medullary cavity formation in group B; and gradually decreased blood vessels, the mature bone structure formation, and the re-opened medullary cavity in group C at 12 and 16 weeks. The immunohistochemical staining observation showed that the levels of CD105, CD34, and factor VIII were higher in group C than in groups A and B at different time points. The bone morphometry analysis showed that the trabecular volume increased gradually with time in 3 groups after operation; the trabecular volume in group C was significantly more than those in groups A and B at different time points (P < 0.05); and there was significant difference between groups A and B (P < 0.05) except the volume at 4 weeks (P > 0.05). The vascular image analysis showed that the vascular regenerative area ratio in group C was significantly higher than those in groups A and B at different time points (P < 0.05). The ink perfusion experiment showed that the osteogenic zone had sparse ink area with no obvious change in group B, while the osteogenic zone had more intensive ink area and reached the peak at 8 weeks, then decreased in group C. CONCLUSION: The tissue engineered bone with pedicled fascial flap packing ARBM has the vascularization osteogenesis effect at early stage, but the effect disappears at late stage gradually when the membrane guided osteogenesis is main.

[Experimental study of repairing bone defect with tissue engineered bone seeded with autologous red bone marrow and wrapped by pedicled fascial flap].

OBJECTIVE: To investigate the effect of repairing bone defect with tissue engineered bone seeded with the autologous red bone marrow (ARBM) and wrapped by the pedicled fascial flap and provide experimental foundation for clinical application. METHODS: Thirty-two New Zealand white rabbits (male and/or female) aged 4-5 months old and weighing 2.0-2.5 kg were used to make the experimental model of bilateral 2 cm defect of the long bone and the periosteum in the radius. The tissue engineered bone was prepared by seeding the ARBM obtained from the rabbits on the osteoinductive absorbing material containing BMP. The left side of the experimental model underwent the implantation of autologous tissue engineered bone serving as the control group (group A). While the right side was designed as the experimental group (group B), one 5 cm x 3 cm fascial flap pedicled on the nameless blood vessel along with its capillary network adjacent to the bone defect was prepared using microsurgical technology, and the autologous tissue engineered bone wrapped by the fascial flap was used to fill the bone defect. At 4, 8, 12, and 16 weeks after operation, X-ray exam, absorbance (A) value test, gross morphology and histology observation, morphology quantitative analysis of bone in the reparative area, vascular image analysis on the boundary area were conducted. RESULTS: X-ray films, gross morphology observation, and histology observation: group B was superior to group A in terms of the growth of blood vessel into the implant, the quantity and the speed of the bone trabecula and the cartilage tissue formation, the development of mature bone structure, the remodeling of shaft structure, the reopen of marrow cavity, and the absorbance and degradation of the implant. A value: there was significant difference between two groups 8, 12, and 16 weeks after operation (P < 0.05), and there were significant differences among those three time points in groups A and B (P < 0.05). For the ratio of neonatal trabecula area to the total reparative area, there were significant differences between two groups 4, 8, 12, and 16 weeks after operation (P < 0.05), and there were significant differences among those four time points in group B (P < 0.05). For the vascular regenerative area in per unit area of the junctional zone, group B was superior to group A 4, 8, 12, and 16 weeks after operation (P < 0.05). CONCLUSION: Tissue engineered bone, seeded with the ARBM and wrapped by the pedicled fascial flap, has a sound reparative effect on bone defect due to its dual role of constructing vascularization and inducing membrane guided tissue regeneration.