We previously prepared nerve growth factor poly-lactide co-glycolid sustained-release microspheres to treat rat sciatic nerve injury using the small gap sleeve technique.Multiple growth factors play a synergistic role...We previously prepared nerve growth factor poly-lactide co-glycolid sustained-release microspheres to treat rat sciatic nerve injury using the small gap sleeve technique.Multiple growth factors play a synergistic role in promoting the repair of peripheral nerve injury;as a result,in this study,we added basic fibroblast growth factors to the microspheres to further promote nerve regeneration.First,in an in vitro biomimetic microenvironment,we developed and used a drug screening biomimetic microfluidic chip to screen the optimal combination of nerve growth factor/basic fibroblast growth factor to promote the regeneration of Schwann cells.We found that 22.56 ng/mL nerve growth factor combined with 4.29 ng/mL basic fibroblast growth factor exhibited optimal effects on the proliferation of primary rat Schwann cells.The successfully prepared nerve growth factor-basic fibroblast growth factor-poly-lactide-co-glycolid sustained-release microspheres were used to treat rat sciatic nerve transection injury using the small gap sleeve bridge technique.Compared with epithelium sutures and small gap sleeve bridging alone,the small gap sleeve bridging technique combined with drug-free sustained-release microspheres has a stronger effect on rat sciatic nerve transfection injury repair at the structural and functional level.展开更多
The clinical effects of 2-mm small gap sleeve bridging of the biological conduit to repair periph- eral nerve injury are better than in the traditional epineurium suture, so it is possible to replace the epineurium su...The clinical effects of 2-mm small gap sleeve bridging of the biological conduit to repair periph- eral nerve injury are better than in the traditional epineurium suture, so it is possible to replace the epineurium suture in the treatment of peripheral nerve injury. This study sought to identify the regeneration law of nerve fibers in the biological conduit. A nerve regeneration chamber was constructed in models of sciatic nerve injury using 2-mm small gap sleeve bridging of a biodegradable biological conduit. The results showed that the biological conduit had good his- tocompatibility. Tissue and cell apoptosis in the conduit apparently lessened, and regenerating nerve fibers were common. The degeneration regeneration law of Schwann cells and axons in the conduit was quite different from that in traditional epineurium suture. During the prime period for nerve fiber regeneration （2-8 weeks）, the number of Schwann cells and nerve fibers was higher in both proximal and distal ends, and the effects of the small gap sleeve bridging method were better than those of the traditional epineurium suture. The above results provide an objec- tive and reliable theoretical basis for the clinical application of the biological conduit small gap sleeve bridging method to repair peripheral nerve injury.展开更多
Dedifferentiation of Schwann cells is an important feature of the response to peripheral nerve injury and specific negative myelination reg- ulators are considered to have a major role in this process. However, most e...Dedifferentiation of Schwann cells is an important feature of the response to peripheral nerve injury and specific negative myelination reg- ulators are considered to have a major role in this process. However, most experiments have focused on the distal nerve stump, where the Notch signaling pathway is strongly associated with Schwann cell dedifferentiation and repair of the nerve. We observed the phenotypic changes of Schwann cells and changes of active Notch signaling on the proximal stump during peripheral nerve repair using small gap conduit tubulization. Eighty rats, with right sciatic nerve section of 4 mm, were randomly assigned to conduit bridging group and control group （epineurium suture）. Glial fibrillary acidic protein expression, in myelinating Schwann cells on the proximal stump, began to up-reg- ulate at 1 day after injury and was still evident at 5 days. Compared with the control group, Notchl mRNA was expressed at a higher level in the conduit bridging group during the first week on the proximal stump. Hesl mRNA levels in the conduit bridging group significantly increased compared with the control group at 3, 5, 7 and 14 days post-surgery. The change of the Notch intracellular domain shared a simi- lar trend as Hesl mRNA expression. Our results confirmed that phenotypic changes of Schwann cells occurred in the proximal stump. The differences in these changes between the conduit tubulization and epineurium suture groups correlate with changes in Notch signaling. This suggests that active Notch signaling might be a key mechanism during the early stage of neural regeneration in the proximal nerve stump.展开更多
Structural design and tests on the characteristics of the SF6 gas switch with a small gap are presented. This kind of switch often works under high pressure and nanosecond pulse for getting pulse with faster risetime....Structural design and tests on the characteristics of the SF6 gas switch with a small gap are presented. This kind of switch often works under high pressure and nanosecond pulse for getting pulse with faster risetime. The breakdown voltage and breakdown delay of a number of switches with different geometries, gas pressures and pulse waveforms were investigated. Experimental results suggested that the breakdown voltage increases linearly with the gas pressure, and the breakdown delay decreases with an increase in the gas pressure and a reduction in the gap distance of the switch under the same applied pulse. By using this kind of switch with a gap of 3 mm as a peaking switch, a pulse generator can provide an output voltage with a peak voltage of 300 kV and a risetime of 3 ns on a resistance load of 150Ω.展开更多
Objective:To study the effect of nerve fragments and small gap suture of epineurium in peripheral nerve repair.Methods:(1)The experimental animals were randomly divided into control group,simple small gap suture group...Objective:To study the effect of nerve fragments and small gap suture of epineurium in peripheral nerve repair.Methods:(1)The experimental animals were randomly divided into control group,simple small gap suture group,small gap suture combined neural debris group;(2)observing the nerve anastomosis after two weeks;(3)testing nerve fiber regeneration after eight weeks;(4)testing gastrocnemius wet weight ratio after eight weeks;(5)pathological image analysis:the number of regenerated nerve fibers,the diameter and myelin thickness of regenerated nerve fiber were measured.Results:(1)Scar tissue was formed in traditional suture anastomotic adhesions;in simple small gap suture group,obvious adhesions was not found surrounding the tissue;for combination group of small gap suture with nerve debris,there was no obvious adhesions,and the outer membrane of small gap turned thinner than before.(2)Compared with the normal control group,the wet weight was increased significantly in the small gap suture group;relative to the small gap group,the wet weight was increased significantly in the small gap plus nerve fragments group.(3)Compared with the control group,the total number of myelinated nerve fibers was increased significantly in the small-gap suture group and small gap plusnerve fragments group;the diameter of nerve fibers and myelin thickness were increased significantly in simple small gap group and the small gap plus nerve debris group.(4)Histology showed:Compared with simple small gap suture group,nerve fiber density was increased,arrangement is neat in the small gap plus nerve fragments group.Conclusions:The nerve fragments plus epineurium small gap suture has a significant role in the repair of peripheral nerve injury.展开更多
During peripheral nerve transposition repair, if the diameter difference between transposed nerves is large or multiple distal nerves must be repaired at the same time, traditional epineurial neurorrhaphy has the prob...During peripheral nerve transposition repair, if the diameter difference between transposed nerves is large or multiple distal nerves must be repaired at the same time, traditional epineurial neurorrhaphy has the problem of high tension at the suture site, which may even lead to the failure of nerve suture. We investigated whether a small gap bio-sleeve suture with different inner diameters at both ends can be used to repair a 2-mm tibial nerve defect by proximal transposition of the common peroneal nerve in rats and compared the results with the repair seen after epineurial neurorrhaphy. Three months after surgery, neurological function, nerve regeneration, and recovery of nerve innervation muscle were assessed using the tibial nerve function index, neuroelectrophysiological testing, muscle biomechanics and wet weight measurement, osmic acid staining, and hematoxylin-eosin staining. There was no obvious inflammatory reaction and neuroma formation in the tibial nerve after repair by the small gap bio-sleeve suture with different inner diameters at both ends. The conduction velocity, muscle strength, wet muscle weight, cross-sectional area of muscle fibers, and the number of new myelinated nerve fibers in the biosleeve suture group were similar to those in the epineurial neurorrhaphy group. Our findings indicate that small gap bio-sleeve suture with different inner diameters at both ends can achieve surgical suture between nerves of different diameters and promote regeneration and functional recovery of injured peripheral nerves.展开更多
A kind of small band-gap conjugated polymers-poly (pyrrolyl methines) and their precursors-(poly pyrrolyl methanes) have been synthesized by a simple method and characterized by (HNMR)-H-1, FT-IR, TGA and UV-Vis. Thes...A kind of small band-gap conjugated polymers-poly (pyrrolyl methines) and their precursors-(poly pyrrolyl methanes) have been synthesized by a simple method and characterized by (HNMR)-H-1, FT-IR, TGA and UV-Vis. These polymers can be dissolved in high polar solvents such as DMSO, DMF or NMP. The results reveals that the band-gap of the synthesized conjugated polymers are in the range of 0.96similar to1.14 eV and they all belong to the small band-gap polymers. The conductivity of doped products with iodine is in the range of semiconductor.展开更多
Density functional theory calculations within the G03W package, with B3LYP exchange functional and applying basis set 6 - 31 G (d,p) are performed. The surface reactivity and electronic properties of endo-hydrogenatio...Density functional theory calculations within the G03W package, with B3LYP exchange functional and applying basis set 6 - 31 G (d,p) are performed. The surface reactivity and electronic properties of endo-hydrogenation and exo-hydrogenation fullerene cages are studied. It is found that the surface reactivity of mono-hydrogenation fullerene cages is larger than the surface reactivity of un-hydrogenation fullerene cages and the later is larger than the fully hydrogenation fullerene cages. In addition, the calculations show that the endo-hydrogenation fullerene cages possess the same band gaps as the un-hydrogenation fullerene cages, however, the exo-hydrogenation is reduced the band gaps of the un-hydrogenated fullerene cages form ~7 eV to ~5 eV.展开更多
基金supported by the National Key Research and Development Program of China, No. 2016YFC1101603 (to DYZ)the National Natural Science Foundation of China, Nos. 31640045 (to YHW), 81901251 (to ML)the Natural Science Foundation of Beijing of China, No. 7204323 (to ML)
文摘We previously prepared nerve growth factor poly-lactide co-glycolid sustained-release microspheres to treat rat sciatic nerve injury using the small gap sleeve technique.Multiple growth factors play a synergistic role in promoting the repair of peripheral nerve injury;as a result,in this study,we added basic fibroblast growth factors to the microspheres to further promote nerve regeneration.First,in an in vitro biomimetic microenvironment,we developed and used a drug screening biomimetic microfluidic chip to screen the optimal combination of nerve growth factor/basic fibroblast growth factor to promote the regeneration of Schwann cells.We found that 22.56 ng/mL nerve growth factor combined with 4.29 ng/mL basic fibroblast growth factor exhibited optimal effects on the proliferation of primary rat Schwann cells.The successfully prepared nerve growth factor-basic fibroblast growth factor-poly-lactide-co-glycolid sustained-release microspheres were used to treat rat sciatic nerve transection injury using the small gap sleeve bridge technique.Compared with epithelium sutures and small gap sleeve bridging alone,the small gap sleeve bridging technique combined with drug-free sustained-release microspheres has a stronger effect on rat sciatic nerve transfection injury repair at the structural and functional level.
基金supported by grants from the National Program on Key Basic Research Project of China(973 Program),No.2014CB542200Program for Innovative Research Team in University of Ministry of Education of China,No.IRT1201+1 种基金the National Natural Science Foundation of China,No.31271284,31171150,81171146,30971526,31100860,31040043,31371210Program for New Century Excellent Talents in University of Ministry of Education of China,No.BMU20110270
文摘The clinical effects of 2-mm small gap sleeve bridging of the biological conduit to repair periph- eral nerve injury are better than in the traditional epineurium suture, so it is possible to replace the epineurium suture in the treatment of peripheral nerve injury. This study sought to identify the regeneration law of nerve fibers in the biological conduit. A nerve regeneration chamber was constructed in models of sciatic nerve injury using 2-mm small gap sleeve bridging of a biodegradable biological conduit. The results showed that the biological conduit had good his- tocompatibility. Tissue and cell apoptosis in the conduit apparently lessened, and regenerating nerve fibers were common. The degeneration regeneration law of Schwann cells and axons in the conduit was quite different from that in traditional epineurium suture. During the prime period for nerve fiber regeneration （2-8 weeks）, the number of Schwann cells and nerve fibers was higher in both proximal and distal ends, and the effects of the small gap sleeve bridging method were better than those of the traditional epineurium suture. The above results provide an objec- tive and reliable theoretical basis for the clinical application of the biological conduit small gap sleeve bridging method to repair peripheral nerve injury.
基金supported by the Shandong Science and Research Foundation for Youth Scientists in China,No.BS2012YY019
文摘Dedifferentiation of Schwann cells is an important feature of the response to peripheral nerve injury and specific negative myelination reg- ulators are considered to have a major role in this process. However, most experiments have focused on the distal nerve stump, where the Notch signaling pathway is strongly associated with Schwann cell dedifferentiation and repair of the nerve. We observed the phenotypic changes of Schwann cells and changes of active Notch signaling on the proximal stump during peripheral nerve repair using small gap conduit tubulization. Eighty rats, with right sciatic nerve section of 4 mm, were randomly assigned to conduit bridging group and control group （epineurium suture）. Glial fibrillary acidic protein expression, in myelinating Schwann cells on the proximal stump, began to up-reg- ulate at 1 day after injury and was still evident at 5 days. Compared with the control group, Notchl mRNA was expressed at a higher level in the conduit bridging group during the first week on the proximal stump. Hesl mRNA levels in the conduit bridging group significantly increased compared with the control group at 3, 5, 7 and 14 days post-surgery. The change of the Notch intracellular domain shared a simi- lar trend as Hesl mRNA expression. Our results confirmed that phenotypic changes of Schwann cells occurred in the proximal stump. The differences in these changes between the conduit tubulization and epineurium suture groups correlate with changes in Notch signaling. This suggests that active Notch signaling might be a key mechanism during the early stage of neural regeneration in the proximal nerve stump.
基金supported by National Natural Science Foundation of China (No. 50437030)
文摘Structural design and tests on the characteristics of the SF6 gas switch with a small gap are presented. This kind of switch often works under high pressure and nanosecond pulse for getting pulse with faster risetime. The breakdown voltage and breakdown delay of a number of switches with different geometries, gas pressures and pulse waveforms were investigated. Experimental results suggested that the breakdown voltage increases linearly with the gas pressure, and the breakdown delay decreases with an increase in the gas pressure and a reduction in the gap distance of the switch under the same applied pulse. By using this kind of switch with a gap of 3 mm as a peaking switch, a pulse generator can provide an output voltage with a peak voltage of 300 kV and a risetime of 3 ns on a resistance load of 150Ω.
文摘Objective:To study the effect of nerve fragments and small gap suture of epineurium in peripheral nerve repair.Methods:(1)The experimental animals were randomly divided into control group,simple small gap suture group,small gap suture combined neural debris group;(2)observing the nerve anastomosis after two weeks;(3)testing nerve fiber regeneration after eight weeks;(4)testing gastrocnemius wet weight ratio after eight weeks;(5)pathological image analysis:the number of regenerated nerve fibers,the diameter and myelin thickness of regenerated nerve fiber were measured.Results:(1)Scar tissue was formed in traditional suture anastomotic adhesions;in simple small gap suture group,obvious adhesions was not found surrounding the tissue;for combination group of small gap suture with nerve debris,there was no obvious adhesions,and the outer membrane of small gap turned thinner than before.(2)Compared with the normal control group,the wet weight was increased significantly in the small gap suture group;relative to the small gap group,the wet weight was increased significantly in the small gap plus nerve fragments group.(3)Compared with the control group,the total number of myelinated nerve fibers was increased significantly in the small-gap suture group and small gap plusnerve fragments group;the diameter of nerve fibers and myelin thickness were increased significantly in simple small gap group and the small gap plus nerve debris group.(4)Histology showed:Compared with simple small gap suture group,nerve fiber density was increased,arrangement is neat in the small gap plus nerve fragments group.Conclusions:The nerve fragments plus epineurium small gap suture has a significant role in the repair of peripheral nerve injury.
基金funded by the National Natural Science Foundation of China,No.31571236,31571235(to YHK and PXZ)National Key Research and Development Program of China,No.2016YFC1101604(to DYZ)+2 种基金National Key Basic Research Program of China(973 Program),No.2014CB542200(to BGJ)Ministry of Education Innovation Program of China,No.IRT_16R01(to BGJ)Beijing Science and Technology New Star Cross Program of China,No.2018019(to PXZ)
文摘During peripheral nerve transposition repair, if the diameter difference between transposed nerves is large or multiple distal nerves must be repaired at the same time, traditional epineurial neurorrhaphy has the problem of high tension at the suture site, which may even lead to the failure of nerve suture. We investigated whether a small gap bio-sleeve suture with different inner diameters at both ends can be used to repair a 2-mm tibial nerve defect by proximal transposition of the common peroneal nerve in rats and compared the results with the repair seen after epineurial neurorrhaphy. Three months after surgery, neurological function, nerve regeneration, and recovery of nerve innervation muscle were assessed using the tibial nerve function index, neuroelectrophysiological testing, muscle biomechanics and wet weight measurement, osmic acid staining, and hematoxylin-eosin staining. There was no obvious inflammatory reaction and neuroma formation in the tibial nerve after repair by the small gap bio-sleeve suture with different inner diameters at both ends. The conduction velocity, muscle strength, wet muscle weight, cross-sectional area of muscle fibers, and the number of new myelinated nerve fibers in the biosleeve suture group were similar to those in the epineurial neurorrhaphy group. Our findings indicate that small gap bio-sleeve suture with different inner diameters at both ends can achieve surgical suture between nerves of different diameters and promote regeneration and functional recovery of injured peripheral nerves.
文摘A kind of small band-gap conjugated polymers-poly (pyrrolyl methines) and their precursors-(poly pyrrolyl methanes) have been synthesized by a simple method and characterized by (HNMR)-H-1, FT-IR, TGA and UV-Vis. These polymers can be dissolved in high polar solvents such as DMSO, DMF or NMP. The results reveals that the band-gap of the synthesized conjugated polymers are in the range of 0.96similar to1.14 eV and they all belong to the small band-gap polymers. The conductivity of doped products with iodine is in the range of semiconductor.
文摘Density functional theory calculations within the G03W package, with B3LYP exchange functional and applying basis set 6 - 31 G (d,p) are performed. The surface reactivity and electronic properties of endo-hydrogenation and exo-hydrogenation fullerene cages are studied. It is found that the surface reactivity of mono-hydrogenation fullerene cages is larger than the surface reactivity of un-hydrogenation fullerene cages and the later is larger than the fully hydrogenation fullerene cages. In addition, the calculations show that the endo-hydrogenation fullerene cages possess the same band gaps as the un-hydrogenation fullerene cages, however, the exo-hydrogenation is reduced the band gaps of the un-hydrogenated fullerene cages form ~7 eV to ~5 eV.
