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Identification and Isolation of Human Dental Pulp Stem Cells

生物医学工程学杂志 2005年第S1期22卷 101-102页

作者： Xue-Chao YANG Ming-Wen FAN(ministry education key lab. For Oral Biomedical engineering, Shool of Stomatology, Wuhan University,Wuhan 430079,China) Ministry Education Key Lab. For Oral Biomedical Engineering Shool of Stomatology Wuhan University Wuhan 430079 China

1 IntroductionDentinal repair in the postnatal organism occurs through the activity of specialized cells, odontoblasts,that are thought to be maintained by an as yet undefined precursor population associated with pulp... 详细信息

关键词： cell DPSCs Identification and Isolation of Human Dental Pulp Stem Cells DSPP

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Research progress of epiretinal prosthesis based on electrical stimulation

Research progress of epiretinal prosthesis based on electric...

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2005 First International Conference on Neural Interface and Control

作者： Wang, Xing Peng, Cheng-Lin Yang, Yong Key Lab. for Biomechanics and Tissue Engineering Chongqing University State Ministry of Education Chongqing 400044 China

ISBN: (纸本)0780389026

There are currently many experimental efforts to develop a treatment to restore useful vision for blind patients by electrical stimulation at epiretina, which is based on experiments that inner retinal layers can be electrically stimulated and elicit an electrical-evoked response. Generally, various researches on visual prosthesis are mainly focused on two solutions according to the research emphasis. One type is different designs surrounding the hardware circuitry, the other type is function evaluation and physiological test of artificial retina. On the one hand, there are probably three aspects, which are elementary structure, important factors of structure and biocompatible consideration. Among them, main structure generally consists of about three parts in theory. Moreover, it is claimed that other factors, such as electrode-retina interface and pulse shape, should be taken into account. And the last is material, electrode shape and production technique. On the other hand, in order to demonstrate that epiretinal stimulation actually helps construct a visual prosthesis, functional evaluation and physiological test of the artificial vision is required. At present, researchers mainly used several kinds of animals for vitro biocompatibility tests and vivo biocompatibility tests. Besides that, there are novel alternative which researchers attempted to find. This paper will begin with general considerations related to all or most of retinal prosthesis, and then concentrate on the epiretinal electrical design. At the end of the paper an outlook of the possible trend of epiretinal electrical stimulation in future is presented. © 2005 IEEE.

关键词： Functional electric stimulation

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Analysis of transmembrane potentials induced by pulsed electric field with different durations based on five-shelled dielectric model of cell

Analysis of transmembrane potentials induced by pulsed elect...

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2005 27th Annual International Conference of the engineering in Medicine and Biology Society, IEEE-EMBS 2005

作者： Chenguo, Yao Chengxiang, Li Yan, Mi Caixin, Sun Dengbin, Mo Key Lab. of High Voltage Engineering and Electrical New Technology Ministry of Education Chongqing University Chongqing 400044 China

ISBN: (纸本)0780387406

In order to account for the influence of subcellular organelles on transmembrane potential, five-shelled dielectric model of spherical cell was developed in this paper. And the calculation method of transmembrane potential induced by any pulsed electric field (PEF) was put forward. Thus the effects of different pulse duration on transmembrane potentials of cell membrane and nuclear membrane were also analyzed. It is shown that there is a strong relationship between the amplitude and waveform of transmembrane potential and pulse duration. PEF with shorter duration can reaches into the cell easily, thus with shorter duration pulses, transmembrane potential of nuclear membrane is increasing and close to that of cell membrane. So PEF with shorter duration will bring on some important biological effects, such as electroporation or apoptosis. © 2005 IEEE.

关键词： Cell membranes

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A novel three-phase rectifier topology with double frequency

A novel three-phase rectifier topology with double frequency

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2005 IEEE International Conference on Industrial Technology, ICIT 2005

作者： Luowei, Zhou Xiong, Du Quanming, Luo IEEE Key Lab. of High Voltage Engineering and Electrical New Technology Chongqing University Ministry of Education Chongqing China

ISBN: (纸本)0780394844

A novel topology of three-phase rectifier with double frequency is proposed in this paper. The topology is composed of two standard three-phase bridges, which work in different frequency. The novel converter topology employs the high frequency converter to improve power factor correction performance, and the low frequency one to handle power, so this topology is suitable for high power application with high performance and high efficiency. Because of the cascaded structure, there is no zero-sequence circulating current, which appears in converter's paralleling operation. The new topology has the same performance with the single high frequency three-phase rectifier, but the efficiency is close to a single low frequency one. The simulation and experiment results verify the validity of the proposed new topology and the corresponding control method. © 2005 IEEE.

关键词： Electric rectifiers

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A 3-D microelectrodes array microchip applied to cell fusion

A 3-D microelectrodes array microchip applied to cell fusion

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2005 27th Annual International Conference of the engineering in Medicine and Biology Society, IEEE-EMBS 2005

作者： Zhao, Zhiqiang Zheng, XiaoLin Xiong, Jiangong Cui, Jianguo Wen, Jing Li, Zhiguo Wang, Xing Key Lab. of Biomechanics and Tissue Engineering under the State Education Ministry Bioenginering College Chongqing University 400044 China

ISBN: (纸本)0780387406

A cell-to-cell fusion technique using 3-D microelectrodes array microchip has been developed. It permits cell-to-cell fusion operation in large amount simultaneously. And it needs much lower voltage (alternating voltage and pulse voltage) than the conventional cell fusion techniques. An array of 16 (4×4) microelectrodes can be fabricated on a 1×1cm silicon wafer. And an experimental system, including circuit control unit, temperature control unit, etc., has been developed to fuse cells. The alternating voltage is applied to the electrodes makes cells in alignment and in pairs firstly. Dielectrophoresis (DEP) force is used to form cell pairs in the microchip and makes cell pairs contact each other tightly. And then fusion of the cell pairs is induced by electric pulse is applied between electrodes. Microelectrodes of 8μm carbon-fiber are used to test the feasibility of the proposal experimental system, Human hepatocarcinoma SMMC-7721 cells are used as specimens. It's observed that SMMC-7721 cells formed cell pairs and fused successfully. © 2005 IEEE.

关键词： Microelectrodes

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Research progress of subretinal implant based on electronic stimulation

Research progress of subretinal implant based on electronic ...

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2005 27th Annual International Conference of the engineering in Medicine and Biology Society, IEEE-EMBS 2005

作者： Wang, Xing Peng, Chenglin Zhao, Zhiqiang Luo, Xiaogang Hu, Ning Zhang, Huiquan Key Lab. of Biomechanics and Tissue Engineering under the State Education Ministry Bioengineering College Chongqing University 400044 China

ISBN: (纸本)0780387406

Subretinal prosthesis is one kind of retinal prosthesis, which means that a microimplant based on MEMS technology is inserted in the subretinal space to stimulate the optic nerve and elicit an electrical-evoked response on the cortical region. The subretinal implant is made up of extraocular part and intraocular part. As an important part, the latter consists of accessorial setting and stimulation chip that contains microphotodiode array (MPDA) and microelectrodes. The paper main body is made up of four parts. Firstly significance of the retinal prosthesis is given out;secondly fundamentals on both in retina physiology and retinal prosthesis theory are introduced simply. Then the key segment about the subretinal microimplant is presented in detail. In the third segment, first of all is its design concept, the second is fabrication of MPDA which consists of several parts. First is microscopic configuration, electric prototype schematic and chip image COMS. The second is detailed fabrication flow with several special materials. Then is situation of its dimension. The fourth segment presents challenge and outlook. © 2005 IEEE.

关键词： Implants (surgical)

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A novel buck converter topology with double frequency

A novel buck converter topology with double frequency

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2005 IEEE International Conference on Industrial Technology, ICIT 2005

作者： Luowei, Zhou Xiong, Du Quanming, Luo IEEE Key Lab. of High Voltage Engineering and Electrical New Technology Chongqing University Ministry of Education Chongqing China

ISBN: (纸本)0780394844

A novel topology of Buck converter with double frequency is proposed in this paper. This topology is composed of two-Buck cells cascaded, one of which works in high frequency, and another one works in low frequency. The current flowing through the high frequency cell is diverted by the low frequency one, and which is reduced rapidly, so the high frequency cell can work in very high frequency without adding soft switching method. But the switching loss of the low frequency cell is low because of the lower working frequency, even though almost all current flows through it. So the high frequency cell can work in higher frequency to improve the steady and dynamic response with lower switching loss. The novel converter topology employs the high frequency cell to improve the dynamic and steady response, and the low frequency one to process the power, so the system performance is enhanced, at the same time the efficiency is also improved. The simulation and experiment results verify the validity of the proposed new topology. © 2005 IEEE.

关键词： Electric converters

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Blood compatibility of chitosan immobilized on poly(ethylene terephthalate) surface modified by plasma and ultraviolet grafting

Blood compatibility of chitosan immobilized on poly(ethylene...

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作者： Wang, J. Li, P. Sun, H. Yang, P. Leng, Y.X. Chen, J.Y. Huang, N. Lab. of Surface Engineering of Artificial Organs of Sichuan Key Lab. for Advanced Technologies of Materials of Ministry of Education Southwest Jiaotong University Chengdu 610031 China Institute of Surface Modification National Biomaterials Engineering Research Center China

We report a study involving chitosan chains immobilized on poly (ethylene terephthalate) (PET) films by plasma and ultraviolet (UV) grafting modification. The surface structure of the modified PET is determined by means of attenuated total reflection Fourier transform infraed spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS). The results show that the chains of chitosan are successfully grafted on the surface of PET. Platelet adhesion evaluation in vitro is conducted to examine the blood compatibility in vitro. Scanning electron microscopy (SEM) and optical microscopy reveal that the amounts of adhered, aggregated and morphologically changed platelets are reduced on the chitosan-immobilized PET films. The number of platelet adhered on the modified film is reduced by almost 48% compared to the amount of platelets on the untreated film. Our result thus shows that chitosan immobilized on the PET surface improves blood compatibility.

关键词： Biomedical engineering

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Hemocompatibility of PET (polyethylene terephthalate) films grafted PEG (polyethylene glycol) by plasma surface modification

Hemocompatibility of PET (polyethylene terephthalate) films ...

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作者： Pan, C.J. Wang, J. Sun, H. Huang, N. Lab. of Surface Engineering of Artificial Organs of Sichuan Key Lab. for Advanced Technologies of Materials of Ministry of Education Southwest Jiaotong University Chengdu 610031 China Institute of Surface Modification National Biomaterials Engineering Research Center China

In this paper, polyethylene glycol (PEG) of various different molecular weights was grafted onto PET films using plasma surface grafting modification. The surface structure of PEG-grafted PET films was analyzed by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS), suggesting that the surface structure and composition of PET films changes due to the presence of PEG. Blood compatibility was characterized by in vitro platelet adhesion experiments and coagulation factors. The tests of platelet adhesion and coagulation factors in vitro suggest that PEG grafted onto polymer surfaces can improve the blood compatibility of PET films remarkably. The modified PET films were pre-coated with albumin and fibrinogen respectively;platelet adhesion tests in vitro then indicated that samples pre-coated with albumin have better blood compatibility than with fibrinogen, resulting in the conclusion that the albumin can improve blood compatibility. The contact angle of PEG-grafted films was measured by the sessile drop method and the surface free energy and interface free energy were induced. It is indicated that the PEG-grafted PET films have the characteristic of preferentially adsorbing albumin.

关键词： Polyethylene terephthalates

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The role of surface physical properties on blood compatibility of titanium oxide films synthesized by unbalanced magnetron sputtering

The role of surface physical properties on blood compatibili...

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作者： Leng, Y.X. Yang, P. Chen, J.Y. Xu, L.X. Zhao, A.S. Sun, H. Wang, J. Huang, N. Lab. of Surface Engineering of Artificial Organs of Sichuan Key Lab. for Advanced Technologies of Materials of Ministry of Education Southwest Jiaotong University Chengdu 610031 China Institute of Surface Modification National Biomaterials Engineering Research Center China

Surface modification has shown great potential for improving the hemocompatibility of biomedical materials and devices. In this paper we describe our work on improving blood compatibility with Ti-O thin films prepared by unbalanced DC magnetron sputtering. The structure and surface chemical and physical properties of the films were characterized by X-ray diffraction, X-ray photoelectron spectroscopy (XPS), SEM, sheet resistance tests, and Hall effect measurements. The sheet resistance of the titanium oxide samples increased with oxygen pressure and shows a sharp increase when only TiO2 exists in the films. The band gap, carrier density and sheet resistance of the titanium oxide films synthesized at different oxygen pressure are different. These properties affect blood compatibility significantly. We suggest that the semiconducting nature of n-type Ti-O films with bandgap 3.0-3.2 eV, sheet resistance greater than 1 Ω.cm and carrier density of about 1.17 × 1016cm-2 leads to their excellent blood compatibility.

关键词： Titanium oxides

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