Repetitive magnetic stimulation affects the microenvironment of nerve regeneration and evoked potentials after spinal cord injury

Repetitive magnetic stimulation has been shown to alter local blood flow of the brain, excite the corticospinal tract and muscle, and induce motor function recovery. We established a rat model of acute spinal cord injury using the modified Allen＇s method. After 4 hours of injury, rat models received repetitive magnetic stimulation, with a stimulus intensity of 35% maximum output intensity, 5-Hz frequency, 5 seconds for each sequence, and an interval of 2 minutes. This was repeated for a total of 10 sequences, once a day, 5 days in a week, for 2 consecutive weeks. After repetitive magnetic stimulation, the number of apoptotic cells decreased, matrix metalloproteinase 9/2 gene and protein expression decreased, nestin expression increased, somatosensory and motor-evoked potentials recovered, and motor function recovered in the injured spinal cord. These findings confirm that repetitive magnetic stimulation of the spinal cord improved the microenvironment of neural regeneration, reduced neuronal apoptosis, and induced neuroprotective and repair effects on the injured spinal cord.

Transplantation of erythropoietin gene-modified neural stem cells improves the repair of injured spinal cord

The protective effects of erythropoietin on spinal Here, the eukaryotic expression plasmid pcDNA3.1 cord injury have not been well described. human erythropoietin was transfected into rat neural stem cells cultured in vitro. A rat model of spinal cord injury was established using a free falling object. In the human erythropoietin-neural stem cells group, transfected neural stem cells were injected into the rat subarachnoid cavity, while the neural stem cells group was inject- ed with non-transfected neural stem cells. Dulbecco＇s modified Eagle＇s medium/F12 medium was injected into the rats in the spinal cord injury group as a control. At 1-4 weeks post injury, the motor function in the rat lower limbs was best in the human erythropoietin-neural stem ceils group, followed by the neural stem cells group, and lastly the spinal cord injury group. At 72 hours, compared with the spinal cord injury group, the apoptotic index and Caspase-3 gene and protein expressions were apparently decreased, and the bd-2 gene and protein expressions were noticeably increased, in the tissues surrounding the injured region in the human erythro- poietin-neural stem cells group. At 4 weeks, the somatosensory evoked potential latencies were cavities were clearly smaller and the motor and remarkably shorter in the human erythropoi- etin-neural stem cells group and neural stem cells group than those in the spinal cord injury group. These differences were particularly obvious in the human erythropoietin-neural stem cells group. More CM-Dil-positive cells and horseradish peroxidase-positive nerve fibers and larger amplitude motor and somatosensory evoked potentials were found in the human erythro- poietin-neural stem cells group and neural stem cells group than in the spinal cord injury group. Again, these differences were particularly obvious in the human erythropoietin-neural stem cells group. These data indicate that transplantation of erythropoietin gene-modified neural stem cells into the subarachnoid cavity to help repair spinal cord injury and promote the recovery of spinal cord function better than neural stem cell transplantation alone. These findings may lead to significant improvements in the clinical treatment of spinal cord injuries.

Transplantation of human telomerase reverse transcriptase gene-transfected Schwann cells for repairing spinal cord injury

Transfection of the human telomerase reverse transcriptase（h TERT）gene has been shown to increase cell proliferation and enhance tissue repair.In the present study,h TERT was transfected into rat Schwann cells.A rat model of acute spinal cord injury was established by the modified free-falling method.Retrovirus PLXSN was injected at the site of spinal cord injury as a vector to mediate h TERT gene-transfected Schwann cells（1×10^（10）/L;10μL）or Schwann cells（1×10^（10）/L;10μL）without h TERT gene transfection.Between 1 and 4 weeks after model establishment,motor function of the lower limb improved in the h TERT-transfected group compared with the group with non-transfected Schwann cells.Terminal deoxynucleotidyl transferase-mediated d UTP nick-end labeling and reverse transcription-polymerase chain reaction results revealed that the number of apoptotic cells,and gene expression of aquaporin 4/9 and matrix metalloproteinase 9/2decreased at the site of injury in both groups;however,the effect improved in the h TERT-transfected group compared with the Schwann cells without h TERT transfection group.Hematoxylin and eosin staining,PKH26 fluorescent labeling,and electrophysiological testing demonstrated that compared with the non-transfected group,spinal cord cavity and motor and sensory evoked potential latencies were reduced,while the number of PKH26-positive cells and the motor and sensory evoked potential amplitude increased at the site of injury in the h TERT-transfected group.These findings suggest that transplantation of h TERT gene-transfected Schwann cells repairs the structure and function of the injured spinal cord.

Hyperbaric oxygen therapy combined with Schwann cell transplantation promotes spinal cord injury recovery

Schwann cell transplantation and hyperbaric oxygen therapy each promote recovery from spinal cord injury, but it remains unclear whether their combination improves therapeutic results more than monotherapy. To investigate this, we used Schwann cell transplantation via the tail vein, hyperbaric oxygen therapy, or their combination, in rat models of spinal cord contusion injury. The combined treatment was more effective in improving hindlimb motor function than either treatment alone; injured spinal tissue showed a greater number of neurite-like structures in the injured spinal tissue, somatosensory and motor evoked potential latencies were notably shorter, and their amplitudes greater, after combination therapy than after monotherapy. These findings indicate that Schwann cell transplantation combined with hyperbaric oxygen therapy is more effective than either treatment alone in promoting the recovery of spinal cord in rats after injury.

High-cycle fatigue crack initiation and propagation in laser melting deposited TC18 titanium alloy

This article examines fatigue crack nucleation and propagation in laser deposited TC18 titanium alloy. The Widmanstatten structure was obtained by double-annealing treatment,. High-cycle fatigue （HCF） tests were conducted at room temperature with the stress ratio of 0.1 and the notch concentration factor Kt = 1. Fatigue cracks initiated preferentially at micropores, which had great effect on the HCF properties. The effect decreased with the decrease of pore size and the increase of distance from the pore location to the specimen surface. The crack initiation region was characterized by the cleavage facets of a lamella and the tearing of β matrix. The soft a precipitated-free zone formed along grain boundaries accelerated the crack propagation. Subsurface observation indicated that the crack preferred to propagate along the grain boundary α or border of a lamella or vertical to a lamella.

Edaravone combined with Schwann cell transplantation may repair spinal cord injury in rats

Edaravone has been shown to delay neuronal apoptosis, thereby improving nerve function and the microenvironment after spinal cord injury. Edaravone can provide a favorable environment for theAa：eatment of spinal cord injury using Schwann cell transplantation. This study used rat models of complete spinal cord transection at T9. Six hours later, Schwann cells were transplanted in the head and tail ends of the injury site. Simultaneously, edaravone was injected through the caudal vein. Eight weeks later, the PKH-26-1abeled Schwann cells had survived and migrated to the center of the spinal cord injury region in rats after combined treatment with edaravone and Schwann cells. Moreover, the number of PKH-26-1abeled Schwann cells in the rat spinal cord was more than that in rats undergoing Schwann cell transplantation alone or rats without any treatment. Horseradish peroxidase retrograde tracing revealed that the number of horserad- ish peroxidase-positive nerve fibers was greater in rats treated with edaravone combined with Schwann cells than in rats with Schwann cell transplantation alone. The results demonstrated that lower extremity motor function and neurophysiological function were better in rats treated with edaravone and Schwann cells than in rats with Schwann cell transplantation only. These data confirmed that Schwann cell transplantation combined with edaravone injection promoted the regeneration of nerve fibers of rats with spinal cord injury and improved neurological function.

Neuroprotective effects of electroacupuncture on early- and late-stage spinal cord injury

Previous studies have shown that the neurite growth inhibitor Nogo-A can cause secondary neural damage by activating Rho A. In the present study, we hypothesized that electroacupuncture promotes neurological functional recovery after spinal cord injury by inhibiting Rho A expression. We established a rat model of acute spinal cord injury using a modification of Allen＇s method. The rats were given electroacupuncture treatment at Dazhui（Du14）, Mingmen（Du4）, Sanyinjiao（SP6）, Huantiao（GB30）, Zusanli（ST36） and Kunlun（BL60） acupoints with a sparsedense wave at a frequency of 4 Hz for 30 minutes, once a day, for a total of 7 days. Seven days after injury, the Basso, Beattie and Bresnahan（BBB） locomotor scale and inclined plane test scores were significantly increased, the number of apoptotic cells in the spinal cord tissue was significantly reduced, and Rho A and Nogo-A m RNA and protein expression levels were decreased in rats given electroacupuncture compared with rats not given electroacupuncture. Four weeks after injury, pathological tissue damage in the spinal cord at the site of injury was alleviated, the numbers of glial fibrillary acidic protein- and neurofilament 200-positive fibers were increased, the latencies of somatosensory-evoked and motor-evoked potentials were shortened, and their amplitudes were increased in rats given electroacupuncture. These findings suggest that electroacupuncture treatment reduces neuronal apoptosis and decreases Rho A and Nogo-A m RNA and protein expression at the site of spinal cord injury, thereby promoting tissue repair and neurological functional recovery.

Senegenin inhibits neuronal apoptosis after spinal cord contusion injury

Senegenin has been shown to inhibit neuronal apoptosis,thereby exerting a neuroprotective effect.In the present study,we established a rat model of spinal cord contusion injury using the modified Allen＇s method.Three hours after injury,senegenin（30 mg/g） was injected into the tail vein for 3 consecutive days.Senegenin reduced the size of syringomyelic cavities,and it substantially reduced the number of apoptotic cells in the spinal cord.At the site of injury,Bax and Caspase-3 m RNA and protein levels were decreased by senegenin,while Bcl-2 m RNA and protein levels were increased.Nerve fiber density was increased in the spinal cord proximal to the brain,and hindlimb motor function and electrophysiological properties of rat hindlimb were improved.Taken together,our results suggest that senegenin exerts a neuroprotective effect by suppressing neuronal apoptosis at the site of spinal cord injury.

Enhancing Photovoltaic Performance of Ladder-Type Heteroarene-Based Electron Acceptors by Modulating Molecular Packing

Comprehensive Summary,The development of novel building blocks with sp3-hybridized-carbon-free conjugated skeletons is important to further advance and enrich nonfullerene acceptors(NFAs),but this remains a challenge due to the lack of strategies to effectively modulate the aggregation behavior of resulting NFAs.Herein,two novel nitrogen-bridged octacyclic ladder-type heteroarenes end-capped with thiophene rings(BTPS)or selenophene rings(BTPSe)are designed and synthesized as the donor cores for constructing NFAs(MQX-2 and MQX-4).It is found that replacing the sulfur atoms(MQX-2)at the outer positions of the heteroarene core with selenium atoms(MQX-4)can effectively modulate the molecular packing mode of the NFAs.The incorporation of selenium atoms induces stronger O···Se noncovalent interaction than O···S,thus promoting the formation of mixed H/J-type aggregates in MQX-4.Benefiting from more electron hopping channels,MQX-4 exhibits higher electron transport(more than 1-fold enhancement)and photovoltaic properties compared to MQX-2,which forms only H-type aggregates.

Revealing the spacing effect of neighboring side-chains in modulating molecular aggregation and orientation of M-series acceptors

Controlling the aggregation of small-molecule acceptors(SMAs)is essential to obtain an optimal morphology and to improve the photovoltaic performance of polymer solar cells(PSCs).However,reducing intermolecular aggregation of SMAs is usually accompanied by the disruption of compact molecular packing thereby leading to their decreased electron mobilities.Here,two novel M-series SMAs(MD1T and MD2T)based on ladder-type heterononacenes with neighboring side-chains separated by one or two thiophene rings are designed and synthesized.It is found that shortening the spacing of the neighboring side-chains of the SMAs can greatly alleviate the intermolecular aggregation and alter the molecular orientation from bimodal edge-on/face-on to predominant face-on while maintaining the compact molecular packing.As a result,a more favorable morphology with smaller domain sizes is formed for the MD1T-based blend films,which greatly improves the charge generation and charge transport for the corresponding PSCs.The best-performing MD1T-based device affords an efficiency of 12.43%,over seven times higher than that of the MD2T-based device.This work reveals the importance of the spacing between the neighboring side-chains in modulating the molecular aggregation and active layer morphology,and the obtained structure-performance relationships shall provide important guidance for designing highly efficient SMAs.

Effect of thermal deformation on microstructure and properties of TC18 titanium alloy produced by laser additive manufacturing

Grain boundary of α phase damaged ductility of laser melting-deposited TC18 titanium alloy and grain boundary of α phases were difficult to break by nominal heat treatment. An extra thermal deformation was introduced to break the grain boundary of α phase with the improved mechanical property of TC18 titanium alloy fabricated by laser melting deposition technique.Results indicated that after thermal deformation, β grains in alloy seriously elongated. When sample was deformed at temperatures from 750 to 850 ℃, α phase exhibited both rod and irregular morphologies with discontinuous distribution at grain boundary, and the subsequent heat treatment would lead to spheroidization of the α phase. However, after deformation at 900 ℃, α phase transferred into β phase and the subsequent heat treatment would make continuous grain boundary of α phase reappear. The suitable hot deformation can effectively break the continuous grain boundary in laser melting-deposited TC18 alloy with respected improved ductility.