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BACKGROUND: Human walking is closely related to the changes of the surface electromyography signal of the lower limbs, but the difference of electromyography signal under the heterogeneous gait environment has not been studied in depth. OBJECTIVE: To quantitatively analyze the differences of surface electromyography signals of lower limb muscles in heterogeneous gait environments, and study muscle characteristics of lower limb muscles in different phases in heterogeneous footpaths. METHODS: Twenty healthy male subjects were recruited. The surface electromyography signals of lower limb muscles were collected in the environment of straight road, curve road, ramp, and stairs. A complete gait cycle was divided into four phases: the first dual support phase (0%-12%), the single support phase (13%-48%), and the second dual support phase (49%-60%) and swing phase (61%-100%). The muscle activation timing and difference of surface electromyography signal in different gait environments were studied through one-way analysis of variance. This study was approved by the Research Ethics Committee of Tianjin University of Science & Technology. RESULTS AND CONCLUSION: (1) The study showed that compared with the straight path environment, in the process of making turn, the internal and external rotation muscles (Biceps Femoris, Gastrocnemius Medialis, Tibialis Anterior) of hip joint and ankle joint were used to complete the turn. When going upstairs and uphill, in the stage of single support phase, Vastus Lateralis and Vastus Medialis had the most significant difference (P < 0.05), and muscle strength increased significantly. In the second double support phase, the amplitude of Gastrocnemius Medialis increased significantly. When going downstairs and downhill, in the first dual support phase, Vastus Lateralis and Vastus Medialis were required to exert additional assistance. In the single support phase, the amplitudes of Gastrocnemius Medialis and Semitendinosus were significantly increased. In the second double support phase, the amplitude of Gastrocnemius Medialis decreased significantly. (2) The research results can provide reference value for the research and development of the control system of lower limb rehabilitation walking aid. [ABSTRACT FROM AUTHOR]

BACKGROUND: Excessive keratinization of astrocytes after spinal cord injury forms a mechanical barrier to repair the spinal cord and also plays an active role in spinal cord repair and regeneration. The regulation of keratinization to a suitable extent, to make it fully exert positive effects and decrease negative effects, is really a challenge to the research of spinal cord injury. OBJECTIVE: To observe the alteration of sensory neurons and astrocytes in the rat spinal dorsal horn, as well as the expression of interleukin-1β and glial fibrillary acidic protein in the abovementioned cells after a selective dorsal rhizotomy. METHODS: Thirty-three adult healthy Wistar rats were randomly divided into control group (n=3) and experimental group (n=30). On the operation side of the experimental group, the dorsal roots of the left lumbar 3 and 4 spinal nerves were exposed, separated, and cut off, while on the control side of the experimental group, the dorsal roots of the right lumbar 3 and 4 spinal nerves were only exposed and separated. The control group did not undergo any treatment. The rats were sacrificed under anesthesia at 1, 2, and 4 weeks after operation, and the segmental tissues of lumbar segments 3 and 4 were taken to make paraffin sections. The morphological changes of neurons and astrocytes in the rat spinal dorsal horn were observed by hematoxylin-eosin staining. The expression of interleukin-1β and glial fibrillary acidic protein in the spinal cord dorsal horn was observed by immunohistochemical staining. RESULTS AND CONCLUSION: (1) Hematoxylin-eosin staining: 1 and 2 weeks after selective dorsal rhizotomy, there were changes in the nuclei and cytoplasm of sensory neurons on the surgical side of the experimental group and at 4 weeks after operation, apoptosis in neurons appeared. Astrocytes were activated and the number of the cells increased accompanied by enlarged cell body and increased processes and reached a peak at 2 weeks after operation. The number of sensory nerve fibers on the surgical side of the experimental group was less than that on the control side of the experimental group and in the control group at 2 and 4 weeks after operation (P < 0.05), while the number of astrocytes was higher than that on the control side of the experimental group and in the control group at 1, 2, and 4 weeks after operation (P < 0.05). (2) Immunohistochemical staining: The positive expressions of interleukin-1β and glial fibrillary acidic protein on the surgical side of the experimental group were enhanced and peaked at 2 weeks after selective dorsal rhizotomy. The average absorbance values of glial fibrillary acidic protein and interleukin-1β positive cells on the surgical side of the experimental group were higher than those on the control side of the experimental group and in the control group (P < 0.05). (3) To conclude, selective dorsal rhizotomy can lead to a decrease in the number of sensory neurons in the dorsal horn of the spinal cord, reactive proliferation of astrocytes, and increased expression of interleukin-1β and glial fibrillary acidic protein. [ABSTRACT FROM AUTHOR]

BACKGROUND: Neural stem cells are a group of cells that can self-proliferate and have multidirectional differentiation potential. In utero electroporation, which is the most direct and reliable method to study the development of cerebral cortex in vivo, can transduce RNA or plasmids into neural stem cells of mice to interfere with or overexpress target genes. OBJECTIVE: To optimize the conditions of in utero electroporation by targeting neural stem cells in the subependymal region of embryonic mice and using enhanced green fluorescent protein as the reporter gene, so as to provide an effective method for studying the development of cerebral cortex. METHODS: Adult ICR mice were mated at the ratio of one male to three female mice. The mice were caged at 8 p.m., and female mice with vaginal embolus were tested at 8 a.m. the next morning. The female mice with vaginal embolus were counted as 0.5-day pregnancy. On embryonic day 14 (E14), the pregnant mice were intraperitoneally anesthetized with ketamin (120 mg/kg) and xylazine (10 mg/kg). After shaving off the hair of the pregnant mouse’s abdomen and opening the abdominal cavity without cutting the pregnant mouse’s uterus, pEx-4-eGFP plasmid was transfected into neural stem cells of the subependymal region of fetal mice at different voltages using ECM803 electroporation transfection instrument and BTX electrode. After 3 days of transfection, the transfected mouse brain tissue was removed and frozen sections were performed to observe the expression of enhanced green fluorescent protein fluorescence on the cerebral cortex. The number of enhanced green fluorescent protein-positive cells was counted to evaluate the transfection efficiency. RESULTS AND CONCLUSION: (1) The survival and transfection effect of mice were different at 38, 40, 42, and 45 V. The mortality of fetal mice was less at 38 V, but the transfection efficiency was lower. Mice treated at 42 V survived and the fluorescence intensity of enhanced green fluorescent protein was higher in the brain tissue treated at 42 V than in the brain treated at 40 V. However, 45 V was more lethal to mice. Therefore, 42 V was a better transformation condition. (2) Under the condition of 42 V, enhanced green fluorescent protein positive cells were more and the fluorescence was brighter after the pulse was changed from 5 to 8. (3) The improved conditions had no effect on the growth of transfected cortical cells. [ABSTRACT FROM AUTHOR]

BACKGROUND: On the basis of studying the proliferation and osteogenic differentiation of bone marrow mesenchymal stem cells, it is one of the hot topics in regenerative medicine to reveal their migration mechanism. OBJECTIVE: To investigate the effects of concentrated growth factor on proliferation, osteogenic differentiation, and migration of rat bone marrow mesenchymal stem cells. METHODS: Concentrated growth factor was extracted from rat heart vein by variable speed centrifugation. Rat bone marrow mesenchymal stem cells were cultured in vitro and divided into experimental and control groups. Cells in the experimental groups were cultured in α-MEM complete medium supplemented with 5%, 10% and 20% concentrated growth factors by volume fraction, separately. Cells in the control group were cultured in α-MEM complete medium without concentrated growth factor. Cell proliferation was detected by CCK-8 assay. Cell migration was detected by scratch test and Transwell migration chamber assay. Osteogenic differentiation was detected by alizarin red staining. RESULTS AND CONCLUSION: (1) Concentrated growth factor with different volume fractions could promote the proliferation of rat bone marrow mesenchymal stem cells with different volume fractions. (2) The scratch test showed that the migration of rat bone marrow mesenchymal stem cells could be promoted in the experimental groups, and the migration rate of 10% concentrated growth factor group was fastest at 12 hours. Transwell migration chamber assay showed that the number of migrated rat bone marrow mesenchymal stem cells in the experimental groups was higher than that in the control group. The number of migrated rat bone marrow mesenchymal stem cells was highest in the 10% concentrated growth factor group. (3) Alizarin red staining showed that the total number of calcium nodules in the experimental groups was higher than that in the control group on day 7. (4) The results showed that all concentrated growth factors with different volume fractions could promote the proliferation, differentiation, and migration of rat bone marrow mesenchymal stem cells in vitro. The 10% concentrated growth factor had a faster ability to promote the migration of rat bone marrow mesenchymal stem cells. [ABSTRACT FROM AUTHOR]

BACKGROUND: Neural stem cells are a group of cells that can self-proliferate and have multidirectional differentiation potential. In utero electroporation,which is the most direct and reliable method to study the development of cerebral cortex in vivo, can transduce RNA or plasmids into neural stem cells of mice to interfere with or overexpress target genes.OBJECTIVE: To optimize the conditions of in utero electroporation by targeting neural stem cells in the subependymal region of embryonic mice and using enhanced green fluorescent protein as the reporter gene, so as to provide an effective method for studying the development of cerebral cortex.METHODS: Adult ICR mice were mated at the ratio of one male to three female mice. The mice were caged at 8 p.m., and female mice with vaginal embolus were tested at 8 a.m. the next morning. The female mice with vaginal embolus were counted as 0.5-day pregnancy. On embryonic day 14（E14）,the pregnant mice were intraperitoneally anesthetized with ketamin（120 mg/kg） and xylazine（10 mg/kg）. After shaving off the hair of the pregnant mouse’s abdomen and opening the abdominal cavity without cutting the pregnant mouse’s uterus, pEx-4-eGFP plasmid was transfected into neural stem cells of the subependymal region of fetal mice at different voltages using ECM803 electroporation transfection instrument and BTX electrode. After 3 days of transfection, the transfected mouse brain tissue was removed and frozen sections were performed to observe the expression of enhanced green fluorescent protein fluorescence on the cerebral cortex. The number of enhanced green fluorescent protein-positive cells was counted to evaluate the transfection efficiency.RESULTS AND CONCLUSION:（1） The survival and transfection effect of mice were different at 38, 40, 42, and 45 V. The mortality of fetal mice was less at 38 V, but the transfection efficiency was lower. Mice treated at 42 V survived and the fluorescence intensity of enhanced green fluorescent protein was higher in the brain tissue treated at 42 V than in the brain treated at 40 V. However, 45 V was more lethal to mice. Therefore, 42 V was a better transformation condition.（2） Under the condition of 42 V, enhanced green fluorescent protein positive cells were more and the fluorescence was brighter after the pulse was changed from 5 to 8.（3）The improved conditions had no effect on the growth of transfected cortical cells. [ABSTRACT FROM AUTHOR]