H D Li

Tsinghua University, Peping, Beijing, China

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Publications (52)84.72 Total impact

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    ABSTRACT: Brain tissue engineering in the postinjury brain represents a promising option for cellular replacement and rescue, providing a cell scaffold for either transplanted or resident cells. In this article, a hyaluronic acid (HA)-poly-D-lysine (PDL) copolymer hydrogel with an open porous structure and viscoelastic properties similar to neural tissue has been developed for brain tissue engineering. The chemicophysical properties of the hydrogel with HA:PDL ratios of 10:1, 5:1, and 4:1 were investigated by scanning electron microscopy (SEM) and X-ray photoelectron spectrometry. Neural cells cultured in the hydrogel were studied by phase-contrast microscope and SEM. The incorporation of PDL peptides into the HA-PDL hydrogel allowed for the modulation of neuronal cell adhesion and neural network formation. Macrophages and multinucleated foreign body giant cells found at the site of implantation of the hydrogel in the rat brain within the first weeks postimplantation decreased in numbers after 6 weeks, consistent with the host response to inert implants in numerous tissues. Of importance was the infiltration of the hydrogel by glial fibrillary acidic protein-positive cells-reactive astrocytes-by immunohistochemistry and the contiguity between the hydrogel and the surrounding tissue demonstrated by SEM. These findings indicated the compatibility of this hydrogel with brain tissue. Collectively, the results demonstrate the promise of an HA-PDL hydrogel as a scaffold material for the repair of defects in the brain.
    No preview · Article · Mar 2005 · Tissue Engineering
  • W.M. Tian · C.L. Zhang · S.P. Hou · X Yu · F.Z. Cui · Q.Y. Xu · S.L. Sheng · H Cui · H.D. Li
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    ABSTRACT: Nogo-66 and NgR are important receptors inhibiting neuronal regeneration and therefore are targets for treating CNS injury. Antagonists of this receptor including blocking antibodies are potential therapeutic agents for CNS axonal injuries such as spinal cord and brain trauma. A new antibody (IgG) releasing system has been developed by covalently attaching IgG to the biodegradable hyaluronic acid (HA) hydrogel via the hydrolytically unstable hydrazone linkage, aiming to deliver the antibody of CNS regeneration inhibitors to the injured brain. In this paper we describe the synthesis, physico-chemical characteristics and test results of biological activity of antibody released from hyluronic acid hydrogel. To form the conjugates the antibody is attached to the polymer backbone using a condensation reaction between aldehyde group of the antibody and hydrazide group of the HA hydrogel. Furthermore, pH sensitive linkage-hydrozone has been formed between hydrogel and antibody. The amount of conjugated antibodies can reach 135 microg antibody/mg hydrogel in the dry state. At low pH, the antibodies released quite fast. However, the antibodies released much slower in neutral and alkaline environment. The bioactivity of antibody released from hydrogel was retained as demonstrated by indirect immunofluorescence technique.
    No preview · Article · Feb 2005 · Journal of Controlled Release
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    W. Y Zou · Q Cai · F. Z Cui · H. D Li
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    ABSTRACT: In summary, a new method for the electrochemical preparation of mesoporous alloy of Cu/Cu2O film was introduced. In terms of hierarchical order structure, the best results were achieved using low concentration of the anionic surfactant SDS (<10 wt.%). Through XRD, TEM, SEM and energy spectrum analysis, the film has been characterized as a mesoporous Cu/Cu2O film with hexagonal mesophase and high-quality atom-scale cubic crystalline framework. In combination with the results, this suggests that the growth of the film is accomplished through a deposition process of copper ions-coated rod-like micelles.
    Preview · Article · Apr 2003 · Materials Letters
  • F Li · Q.L Feng · F.Z Cui · H.D Li · H Schubert
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    ABSTRACT: A biomimetic calcium phosphate coating is expected to enhance the bioactivity and bone inductivity of human implants. This study presents a very simple, highly effective biomimetic method to obtain a calcium phosphate coating on a titanium substrate. Using NaH2PO4, a stable solution was prepared with high calcium and phosphate ion concentrations. This solution turned to a supersaturated calcification solution (SCS) when NaHCO3 was added. The addition of NaHCO3 elevated the pH value of the solution gradually and steadily. A uniform coating approximately 40 μm thick was found on the substrates after 24 h immersion. The compositions of the coatings were adjustable from hydroxyapatite (HA) to HA/dicalcium phosphate dihydrate (DCPD). The calcium phosphate deposits were investigated by means of scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transformed infrared (FT-IR) spectroscopy.
    No preview · Article · May 2002 · Surface and Coatings Technology
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    Q. L Feng · X Zhu · H. D Li · T. N Kim
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    ABSTRACT: The structure and crystallographic orientation of different layers (the cone layer, palisade layer and the crystal layer) in ostrich eggshells were studied by scanning electron microscope (SEM), X-ray diffraction (XRD) and transmission electron microscope (TEM) with selected area electron diffraction (SAED). It is found that the degree of 001 preferred orientation enhanced from inner to outer ostrich eggshells. A crystallographic orientation regulation was observed for the first time. The adjacent 1–5 calcite crystals with the same three-dimensional orientation are proposed to form a crystalline cluster with the size of several microns. The a-axes in the neighboring clusters orient from several degrees to tens of degrees.
    Full-text · Article · Dec 2001 · Journal of Crystal Growth
  • Z. S Luo · F. Z Cui · Q. L Feng · H. D Li · X. D Zhu · M Spector
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    ABSTRACT: Degradability is among the most important properties in the biomedical field, which is crucial to bone apposition on implants, bone-implant bonding and implantation longevity. The present paper evaluated the degradability of ion beam-assisted deposition (IBAD) hydroxyapatite (HA) coatings in vitro and in vivo. In vitro testing showed that IBAD HA coatings degraded little in 37°C sterile Hank’s physiologic (pH 5.2) balanced salt solution throughout the testing time, while the plasma-sprayed HA coating tested in comparison underwent an increasing degradation: the concentration of Ca increased from the initial 1 ml to 2.75 ml at 3 days post-incubation. In vivo testing revealed that no significant degradation occurred throughout the whole implant period (12 weeks). All the results consistently suggest that the IBAD HA coating is slightly degradable. High magnification SEM observation and HRTEM investigations of the coating further pointed out that the low degradability of the IBAD HA coating derives from its dense microstructure and unique properties such as no sharp grain boundaries. The present study demonstrates that IBAD HA coatings are much more chemically stable than plasma-sprayed HA coatings. The IBAD HA coating possesses more superior adhesive properties, as would be of clinical importance in that it may favor a longer longevity of orthopedic implants.
    No preview · Article · Sep 2000 · Surface and Coatings Technology
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    H W Xu · X C Li · H D Li · H Z Ruan · Z Z Liu
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    ABSTRACT: To investigate the effects of corticotrophin (Cor) on corticotropin-releasing factor (CRF), brain-derived neurotrophic factor (BDNF), and its functional receptor trkB in the frontal cortex of complete Freud's adjuvant (CFA)-induced arthritic rats. The chronic pain rat model was modified and pain behaviour scores were assessed. BDNF-immunoreactivity (IR), trkB-IR, and CRF mRNA-positive neurons were measured by immunohistochemistry and in situ hybridization methods. Compared with control rats, pain behavior scores, BDNF-IR, CRF mRNA-positive, trkB-IR, and BDNF/CRF mRNA double-labeling neurons in the contralateral frontal cortex of the arthritic rats increased significantly at 24 h after injection of CFA (P < 0.05), and these effects were decreased markedly by i.p. injection of Cor (P < 0.05). The decrease in pain behavior and BDNF-IR, CRF mRNA levels in frontal cortex of arthritic rats due to Cor were partly prevented by adrenalectomy (ADX). The increment in BDNF and CRF levels in the contralateral frontal cortex of arthritic rats may be inhibited by corticotrophin.
    Full-text · Article · Aug 2000 · Acta Pharmacologica Sinica
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    Q.L. Feng · F.Z. Cui · G. Pu · R.Z. Wang · H.D. Li
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    ABSTRACT: Based on the investigations of crystal structure of nacre using SEM, TEM and XRD, it is proposed that there exists a domain structure of crystal orientation in the nacre. The orientation domain consists of continuous 3–10 tablets along the direction perpendicular to nacreous plane, and 1–5 tablets in a single lamina. The tablets in a domain are crystallographic identical in three dimensions. From the crack morphologies, it is found that the crack deflection, fibre pull-out and organic matrix bridging are the three main toughening mechanisms acting on nacre. The organic matrix plays an important role in the toughening of this biological composite. The biomimetically synthesized composite made of alumina and kevlar showed significant increase in the fracture energy compared with the single ceramics. The soluble proteins extracted from nacre can induce aragonite and the one from prism can induce calcite grown with a preferred orientation of [104]. The insoluble proteins control the nucleation site and thus lead to a finer crystallization of CaCO3.
    Full-text · Article · Jun 2000 · Materials Science and Engineering C
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    ABSTRACT: The structure and crystallographic orientation of mineral phase in the oblique prismatic layer of Mytilus edulis shell were studied by SEM, XRD and TEM with selected area electron diffraction (SAED). A crystallographic orientation regulation, i.e. the adjacent 1–5 calcite prisms with the same three-dimensional orientation in the oblique prismatic layer, was found for the first time. It is observed that the calcite prisms in the oblique prismatic layer were grown with their (104) parallel to the shell surface.
    Full-text · Article · Jan 2000 · Journal of Materials Science
  • X Wu · H D Li · X C Li · H Z Ruan · J Wang
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    ABSTRACT: To study the effects of intra-hippocampal injection of interleukin-2 (IL-2) on the substance P-like immunoreactivity (SP-LI) in both periaqueductal gray (PAG) and spinal cord, and on pain threshold in rats. Immunohistochemistry technique was used and the paw withdrawal threshold to radiant heat was measured. Microinjection of hIL-2 480 U in hippocampus (Hip) increased the pain threshold (93% +/- 57%, P < 0.01). Injection of formaldehyde (For) in one hindpaw decreased SP-LI neuron number on both sides of PAG (2.9 +/- 2.8 vs 22.1 +/- 0.7, 12.3 +/- 2.0 vs 22.4 +/- 1.0, P < 0.01) and increased SP-LI in ipsilateral spinal cord (0.836 +/- 0.015 vs 0.59 +/- 0.09, P < 0.01). Microinjection of hIL-2 480 U in Hip inhibited the effects of For on the SP-LI on both sides of the PAG (11.3 +/- 2.3 vs 2.9 +/- 2.8, 16.9 +/- 3.4 vs 12.3 +/- 2.0, P < 0.05) and spinal cord (0.71 +/- 0.03 vs 0.836 +/- 0.015, P < 0.01). The combination of intraperitoneal injection of corticotropin and intra-hippocampal injection of IL-2 increased the number of SP-LI neurons in PAG furtherly as compared with IL-2 240 U alone (13.6 +/- 3.6 vs 7.6 +/- 4.3, P < 0.05). The analgesic effects of intra-hippocampal injection of IL-2 are mediated, possibly, via the increased of SP in PAG and the decrease of SP in the spinal cord. There is a synergetic relation between IL-2 and corticotropin.
    No preview · Article · Oct 1999 · Zhongguo yao li xue bao = Acta pharmacologica Sinica
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    Q. L. Feng · H. B. Li · F. Z. Cui · H. D. li · T. N. Kim
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    ABSTRACT: A study was conducted to examine the crystal orientation relationships in the single lamina in the nacreous layer of the Mytilus edulis shell. TEM with SAED was performed on individual crystals by using a selective area aperture. Based on the results, a new model was established to predict the growth configuration of nacre.
    Full-text · Article · Sep 1999 · Journal of Materials Science Letters
  • H J Zhou · H D Li · X C Li · H Z Ruan · B Y Zhao
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    ABSTRACT: To study the effects of corticotropin (Cor) on formalin-induced hyperalgesia and the change of nitric-oxide synthase (NOS)-positive neurons in spinal dorsal horn in rats. Measurement of pain intensity rating (PIR), NADPH-d histochemistry, and Fos immunohistochemistry were adopted. The increases of NOS-positive neurons, Fos, NOS/Fos double labelling neurons of the spinal dorsal horn and the PIR after formalin injection were markedly inhibited by intrathecal injecting (ith) Cor (0.5-1.5 U), which were obviously attenuated by L-arginine (Arg, 5-15 nmol, ith), the substrate of NOS. Cor inhibits formalin-induced hyperalgesia by the decrease of NOS-positive neurons in the spinal dorsal horn of rats.
    No preview · Article · Sep 1999 · Zhongguo yao li xue bao = Acta pharmacologica Sinica
  • Q Wu · X C Li · H Z Ruan · H D Li · B Y Zhao
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    ABSTRACT: To study the effect of corticotrophin (Cor) on somatostatin (Som) and its synthesis in spinal dorsal horn induced by formaldehyde in rats. Using double immunohistochemical stainings, and in situ hybridization. Two hours after s.c. formaldehyde (5%, 200 microL) in one hindpaw of rats, the neurons of c-fos-like immunoreactivity (FLI), somatostatin-like immunoreactivity (Som-LI), Som-LI/FLI, and perprosomatostatin mRNA (PPS-mRNA) in ipsilateral spinal dorsal horn were increased obviously, as compared with the control group. The FLI and Som-LI of spinal cord were not changed by i.p. Cor. Cor (25 or 12.5 U.kg-1, i.p.) inhibited the formaldehyde-evoked FLI, Som-LI, Som-LI/FLI, and PPS-mRNA of spinal cord in a dose-dependent manner. The decrease of c-fos or Som level due to i.p. Cor in rats of chronic pain was prevented by raphe nuclei injected cyproheptadine, but not by bicuculline, naloxone, or phentolamin injected to raphe nuclei. The formaldehyde-evoked c-fos expression, Som, and Som synthesis of spinal cord were suppressed by Cor through the serotonin receptor of raphe nuclei.
    No preview · Article · Mar 1999 · Zhongguo yao li xue bao = Acta pharmacologica Sinica
  • Q Wu · X C Li · H Z Ruan · H D Li
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    ABSTRACT: In the present study, the effect of ACTH on the expression of somatostatin and c-fos in the spinal cord and formalin induced pain responses in rats were studied using immunohistochemistry and in situ hybridization. The results showed that subcutaneous injection of formalin in the right hindpaw increased c-fos-like immunoreactivity (FLI), somatostatin-like immunoreactivity (Som-LI), Som-LI/FLI and perprosomatostatin mRNA (PPS-mRNA) in neurones of right spinal dorsal horn and significantly enhanced pain intensity rating. ACTH decreased the FLI,Som-LI, Som-LI/FLI and PPS-mRNA levels of the spinal cord evoked by formalin. The decrease of c-fos or Som level due to intrathecal injection of ACTH in rats with chronic pain was prevented by injection of cyproheptadine, but not by bicuculline and naloxone. The results indicate that the serotonin receptor may be involved in ACTH induced analgesia.
    No preview · Article · Mar 1999 · Sheng li xue bao: [Acta physiologica Sinica]
  • JH Wang · XC Lu · SZ Wen · HD Li · LD Wang
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    ABSTRACT: Teflon film was prepared by ion beam enhanced deposition method. The structure and microtribological properties were studied by PHI-5300, FT-IR, XRD and atomic force and friction force microscope (AFM/ FFM). The results show that the deposited Teflon is in crystalline state, and its structure is the same as the bulk Teflon. There are two periods in the friction and wear tests for Teflon film. When the load is less than 70 nN, the micro friction force is linear with the load, and the Teflon does not have the lubricity. But when the load is greater than 70 nN, the friction force of Teflon film will stay nearly constant, and worn marks will be created in the friction and wear process. The worn depth of Teflon film increases linearly with the load.
    No preview · Article · Jan 1999 · Journal of Materials Science and Technology -Shenyang-
  • H W Song · F Z Cui · X M He · W Z Li · H D Li
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    ABSTRACT: Carbon nitride thin films have been prepared by NH3-ion-beam-assisted deposition with bombardment energies of 200-800 eV at room temperature. These films have been characterized by transmission electron microscopy, Auger electron spectroscopy and x-ray photoelectron spectroscopy for chemical analysis. It was found that the structure of the films varied with the bombardment energy. In the case of 400 eV bombardment, the tiny crystallites immersed on an amorphous matrix were identified to be beta -C3N4. X-ray photoelectron spectroscopy indicated that some carbon atoms and nitrogen atoms form unpolarized covalent bonds in these films.
    No preview · Article · Dec 1998 · Journal of Physics Condensed Matter
  • X Wu · H D Li · X C Li · H Z Ruan · J Wang
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    ABSTRACT: Using method of in situ hybridization, the effects of subcutaneous injection (s.c.) of formalin (For) into one hindpaw (hyperalgesia) on IL-2R beta mRNA expression in hippocampus (Hip) were studied. In addition, the effects of coadministration of morphine (i.p.) or ACTH (i.p.) with For (s.c.) were studied also. It was found that IL-2R beta mRNA was present in normal rat's Hip, intensely in granular cells of dentate gyrus and CA1-CA4 neurons. Subcutaneous injection of For increased IL-2R beta mRNA from 6 h to at least 24 h, reaching a peak at 12 h. Coadministration with morphine enhanced the effects of For on IL-2R beta mRNA expression, but no significant change was found with coadministration of ACTH. The above results suggest that IL-2R might be involved in pain modulation.
    No preview · Article · Nov 1998 · Sheng li xue bao: [Acta physiologica Sinica]
  • H D Li · X C Li · H Z Ruan
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    ABSTRACT: To study the effect of corticotropin (Cor) on c-fos expression induced by formalin in spinal cord of rat and the role of receptors. Using immunohistochemistry and adrenalectomy. Cor inhibited the formalin-evoked c-fos expression in rat spinal cord in a dose-dependent manner. No obvious effect was seen by i.p. Cor 10 U.kg-1, but 25 U.kg-1 reduced the evoked c-fos expression, that was blocked by phentolamine, naloxone, or verapamil, but not much changed by adrenalectomy. The formalin-evoked c-fos expression of rat spinal cord was suppressed by Cor through the alpha-adrenergic receptors, opiate receptors and calcium, but no relation to adrenal glands.
    No preview · Article · Aug 1998 · Zhongguo yao li xue bao = Acta pharmacologica Sinica
  • J. L. He · L. D. Wang · W. Z. Li · H. D. Li
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    ABSTRACT: Inspired by the ingenious architecture of nacre and its outstanding mechanical properties, we prepared nanoscale ceramic (TiC, Si3N4, B4C) /Teflon multilayers by ion beam sputtering deposition at room temperature. The toughness, hardness and tribological properties were systematically investigated as well as the multilayer structures. It was found that the toughness of ceramic/Teflon multilayers were all significantly improved in comparison with the corresponding monolithic ceramic material, but the hardness was decreased. However, there were optimized layer thickness arrangements with which the multilayer toughness and hardness can be favorably combined to obtain better comprehensive properties. It was found by this study that ceramic/polymer multilayers with the optimized layer thickness arrangement had good performance in wear resistance.
    No preview · Article · Jul 1998 · Materials Chemistry and Physics
  • J.L He · W.Z Li · H.D Li · C.H Liu
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    ABSTRACT: Nanoscale TiC–metal (Al, Cu, Fe, W) multilayers were prepared by ion beam sputtering deposition with an intent to study the plastic properties of the ceramic–metal combinations. The multilayers were designed to have different layer thickness arrangements, including component fraction, modulation wavelength, etc. Their toughness and hardness were systematically investigated as well as the laminated structures. It was found that for most TiC–metal multilayers the toughness was significantly improved in comparison with monolithic TiC, but the hardness showed great dependence on the material system. In TiC–Fe and TiC–W systems, the multilayer hardness exhibited a peak value which was even higher than the hardness of TiC. In TiC–Al and TiC–Cu systems, no superhardness effect was detected.
    No preview · Article · May 1998 · Surface and Coatings Technology