6 results on '"Ranxi Zhang"'
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2. Biomechanical study of novel unilateral C1 posterior arch screws and C2 laminar screws combined with an ipsilateral crossed C1–C2 pedicle screw–rod fixation for atlantoaxial instability
- Author
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Ranxi Zhang, Junsong Yang, Chao Liu, Kai Shen, and Zhong-Liang Deng
- Subjects
Joint Instability ,medicine.medical_specialty ,Models, Biological ,Surgical methods ,03 medical and health sciences ,Fixation (surgical) ,0302 clinical medicine ,medicine ,Humans ,Orthopedics and Sports Medicine ,030212 general & internal medicine ,Range of Motion, Articular ,Pedicle screw ,business.industry ,Biomechanics ,General Medicine ,Posterior arch ,Biomechanical Phenomena ,Surgery ,Spinal Fusion ,Atlanto-Axial Joint ,Atlantoaxial instability ,Orthopedic surgery ,Cervical Vertebrae ,Cadaveric spasm ,business ,030217 neurology & neurosurgery - Abstract
Current surgical methods to treat atlantoaxial instability pose potential risks to the surrounding blood vessels and nerves of operative approach. Therefore, more secure and highly effective methods are expected. This study sought to assess the biomechanical efficacy of a novel unilateral double screw-rod fixation system by comparing with traditional and emerging fixation methods in cadaveric models.Ligamentous cervical spines (C0-C7) from ten fresh cadaveric specimens were used to complete range of motion (ROM) test in their intact condition (control group), destabilization, and stabilization after different fixations, including unilateral C1-C2 pedicle screws (PS) with a screw-rod system (Group A), bilateral C1-C2 PS with screw-rod systems (Group B), unilateral C1 posterior arch screws (PAS) and C2 laminar screws (LS) combined with an ipsilateral paralleled C1-C2 PS-rod (Group C), and unilateral C1 PAS and C2 LS combined with an ipsilateral crossed C1-C2 PS-rod (Group D). After that, pullout strength test was performed between PS and PAS using ten isolated atlas vertebras.All fixation groups reduced flexibility in all directions compared with both control group and destabilization group. Furthermore, comparisons among different fixation groups showed that bilateral C1-C2 PS-rod (Group B), unilateral C1 PAS + C2 LS combined with an ipsilateral paralleled C1-C2 PS-rod (Group C) and unilateral C1 PAS + C2 LS combined with an ipsilateral crossed C1-C2 PS-rod (Group D) could provide a better stability, respectively, in all directions than unilateral C1-C2 PS-rod (Group A). However, no statistical significance was observed among Groups B, C, and D. Data from pullout strength test showed that both C1 PS (585 ± 53 N) and PAS (463 ± 49 N) could provide high fixed strength, although PS was better (P = 0.009).The surgical technique of unilateral C1 PAS + C2 LS combined with a ipsilateral crossed C1-C2 PS-rod fixation could provide a better stability than the traditional unilateral PS-rod fixation and a same stability as bilateral PS-rod fixation, but with less risk of neurovascular injury. Therefore, this new technique may provide novel insight for an alternative of atlantoaxial instability treatment.
- Published
- 2017
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3. Long Non-coding RNA Maternally Expressed 3 Increases the Expression of Neuron-Specific Genes by Targeting miR-128-3p in All-Trans Retinoic Acid-Induced Neurogenic Differentiation From Amniotic Epithelial Cells
- Author
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Yuhua Gao, Ranxi Zhang, Guanghe Wei, Shanshan Dai, Xue Zhang, Wancai Yang, Xiangchen Li, and Chunyu Bai
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0301 basic medicine ,neurogenic differentiation ,Cell ,Notch signaling pathway ,Retinoic acid ,Cell fate determination ,Biology ,AECs ,Cell and Developmental Biology ,03 medical and health sciences ,chemistry.chemical_compound ,lncRNA ,0302 clinical medicine ,microRNA ,medicine ,ATRA ,lcsh:QH301-705.5 ,Original Research ,miRNA ,Competing endogenous RNA ,Cell Biology ,Cell biology ,030104 developmental biology ,medicine.anatomical_structure ,lcsh:Biology (General) ,chemistry ,030220 oncology & carcinogenesis ,Amniotic epithelial cells ,Neuron differentiation ,Developmental Biology - Abstract
MicroRNA (miR)-128-3p is a brain-enriched miRNA that participates in the regulation of neural cell differentiation and the protection of neurons, but the mechanisms by which miR-128-3p regulates its target and downstream genes to influence cell fate from adult stem cells are poorly understood. In this study, we show down-regulation of miR-128-3p during all-trans retinoic acid (ATRA)-induced neurogenic differentiation from amniotic epithelial cells (AECs). We investigated miR-128-3p in both the Notch pathway and in the expression of neuron-specific genes predicted to be involved in miR-128-3p signaling to elucidate its role in the genetic regulation of downstream neurogenic differentiation. Our results demonstrate that miR-128-3p is a negative regulator for the transcription of the neuron-specific genes β III-tubulin, neuron-specific enolase (NSE), and polysialic acid-neural cell adhesion molecule (PSA-NCAM) via targeting Jagged 1 to inhibit activation of the Notch signaling pathway. We also used bioinformatics algorithms to screen for miR-128-3p interactions with long non-coding (lnc) RNA and circular RNA as competing endogenous RNAs to further elucidate underlying down-regulated molecular mechanisms. The lncRNA maternally expressed 3 is up-regulated by the ATRA/cAMP/CREB pathway, and it, in turn, is directly down-regulated by miR-128-3p to increase the amount of neuron differentiation. Endogenous miRNAs are, therefore, involved in neurogenic differentiation from AECs and should be considered during the development of effective cell transplant therapies for the treatment of neurodegenerative disease.
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- 2019
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4. Novel posterior artificial atlanto-odontoid joint for atlantoaxial instability: a biomechanical study
- Author
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Ranxi Zhang, Zhong-Liang Deng, Junsong Yang, Chao Liu, and Kai Shen
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Adult ,Joint Instability ,Male ,Adolescent ,Joint Prosthesis ,Nonunion ,Transverse ligament ,Prosthesis Design ,03 medical and health sciences ,Young Adult ,0302 clinical medicine ,Imaging, Three-Dimensional ,Odontoid Process ,medicine ,Humans ,030212 general & internal medicine ,Range of Motion, Articular ,Joint (geology) ,Fixation (histology) ,Aged ,business.industry ,Soft tissue ,General Medicine ,Anatomy ,Middle Aged ,medicine.disease ,Internal Fixators ,Biomechanical Phenomena ,Atlanto-Axial Joint ,Atlantoaxial instability ,Female ,Spinal Diseases ,business ,Cadaveric spasm ,Range of motion ,Tomography, X-Ray Computed ,030217 neurology & neurosurgery - Abstract
OBJECTIVEAtlantoaxial instability is usually corrected by anterior and/or posterior C1–2 fusion. However, fusion can lead to considerable loss of movement at the C1–2 level, which can adversely impact a patient’s quality of life. In this study, the authors investigated the stability and function of a novel posterior artificial atlanto-odontoid joint (NPAAJ) by using cadaveric cervical spines.METHODSThe Oc–C7 regions from 10 cadaveric spines were used for anteroposterior (AP) translation and range of motion (ROM) tests while intact and after destabilization, NPAAJ implantation, and double-rod fixation.RESULTSThe mean AP C1–2 translational distances in the intact, destabilization, and double-rod groups were 6.53 ± 1.07 mm, 11.54 ± 1.59 mm, and 3.24 ± 0.99 mm, respectively, and the AP translational distance in the NPAAJ group was significantly different from that in the intact group (p < 0.05). The AP translational distance in the NPAAJ group was not significantly different from that in the double-rod group (p = 0.24). The mean flexion, extension, and axial rotation ROM values of the NPAAJ group were 9.87° ± 0.91°, 8.75° ± 0.99°, and 61.93° ± 2.93°, respectively, and these were lower than the corresponding values in the intact group (p < 0.05). The mean lateral bending ROM in the NPAAJ group (9.26° ± 0.86°) was not significantly different from that in the intact group (p = 0.23), and the flexion, extension, and rotation ranges in the NPAAJ group were 79.5%, 85.2%, and 82.3%, respectively, of those in the intact group.CONCLUSIONSUse of NPAAJ for correction of atlantoaxial instability disorders caused by congenital odontoid dysplasia, odontoid fracture nonunion, and C-1 transverse ligament disruption (IA, IB, and IIB) may restore the stability and preserve most of the ROM of C1–2. Additionally, the NPAAJ may prevent soft tissue from embedding within the joint. However, additional studies should be performed before the NPAAJ is used clinically.
- Published
- 2018
5. Determination of magneto-optical characteristics of hexaferrites from 200 GHz to 1THz using time domain spectroscopy
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Bin Yang, Yan Zhang, Ranxi Zhang, and Robert S. Donnan
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Materials science ,Optics ,Terahertz radiation ,business.industry ,Magnet ,Demagnetizing field ,Perpendicular ,Physics::Optics ,Biasing ,Time domain ,Spectroscopy ,Polarization (waves) ,business - Abstract
Gyrotropic, magnetically-hard hexaferrite materials, are very promising candidates to operate as quasi-optical non-reciprocal devices at high frequencies (> 90GHz), with the consequent advantage of obviating the need for requiring extra biasing magnets and avoiding low temperature demagnetization. In this paper, a THz TDS system is used to make measurements on a thin (2.02 mm thickness) hexaferrite plate for both parallel and perpendicular polarisation of the pump beam. From these data, the intrinsic circular-polarisation transmittances of both senses of polarisation are computed and these are analysed to determine the magneto-op tical constants of the hexaferrite plate over the range of 200 GHz to 1THz. Keywords: TDS, Hexaferrite, THz.
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- 2009
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6. Polarization information for terahertz imaging
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Wenfeng Sun, Yan Zhang, Ranxi Zhang, and Ye Cui
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Birefringence ,Materials science ,Polarization rotator ,Terahertz radiation ,business.industry ,Materials Science (miscellaneous) ,Polarization imaging ,Polarizer ,Polarization (waves) ,Industrial and Manufacturing Engineering ,Terahertz spectroscopy and technology ,law.invention ,Optics ,law ,Electric field ,Optoelectronics ,Business and International Management ,business ,Refractive index - Abstract
A method to analyze the variety of the polarization state of terahertz (THz) wave by using a typical electro-optic sampling setup with zinc-blende (ZnTe) crystal as a sensor is presented. To illustrate the knowledge of polarization of the THz pulse, the function of THz detect in ZnTe crystal is interpreted. Two kinds of Jones matrixes, birefringence device and polarizer device, are used to analyses the polarization change of the THz electric field vector caused by the sample. It was found that the THz polarization imaging is sensitive to the edge of the samples.
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- 2008
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