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Biomedical subjects

Han Zhang

Publications and source records attributed to Han Zhang.

At least 37 records · Page 2Linked to original sources
PubMed2006

[Effect of rapamycin and dexamethasone on differentiation and maturation of murine bone marrow-derived dendritic cells].

AIM: To observe the effect of rapamycin (Rap) and dexamethasone (Dex) on differentiation and development of murine bone marrow-derived dendritic cells (DC) in vitro. METHODS: DC cells generated from C57BL/6 murine bone marrow cells were induced by GM-CSF and IL-4. During the course, Rap or Dex was added to the culture and the cells were then stimulated by LPS. (1)Morphology development of DCs was observed by inverted microscope and scanning electron microscope.(2)The cells were analyzed by flow cytometry (FCM) to determine the proportion of CD11c(+) cells and the change of CD86 and MHC class II molecule.(3)The influence of DCs treated by Rap or Dex on the allogeneic T cell proliferation was studied by one-way MLR. RESULTS: (1)The morphology of DCs maintained in a durable state of immaturity after Rap or Dex pretreatment.(2)The expression of CD11c and MHC-II slightly decreased but CD86 dramatically reduced on Rap-treated DC cells. There was close relationship between the expression of CD11c on Dex-treated cells and the dosage of Dex. The surface expression of CD86 and MHC-II dramatically reduced on Dex-treated DCs. Moreover, DCs treated by Rap or Dex were both able to resist the maturation triggered by LPS.(3)Bone marrow-derived DCs cultured with Dex or Rap had a lower stimulatory effect on allogeneic T cells compared with that of mature DCs. CONCLUSION: Rap and Dex could keep DCs in durable immaturity. Compared with Dex, which inhibited the expression of co-stimulatory molecules, Rap hardly influenced the differentiation of DCs and the expression of MHC class II molecules.

Animals↗
PubMed2005

Single-crystalline GdB6 nanowire field emitters.

Having the lowest work function in the rare-earth hexaboride family, GdB6 nanowires of rectangular cross-section with about 50 nm in lateral dimension and several microns in length have been successfully produced using a CVD method. The nanowires are grown in the 001 lattice direction, and both the tip-top and the side surfaces are terminated with the {100} lattice planes. A GdB6 single nanowire field emitter has also been built with an emission current of more than 150 nA at an applied field of less than 3.2 V/mum. The work function of the nanowire emitter was estimated to be about 1.5 eV.

Boron↗
PubMed2005

8-Hydroxyquinoline benzoates as highly sensitive fluorescent chemosensors for transition metal ions.

[graph: see text] 8-Hydroxyquinoline benzoates were developed as a new set of 8-HQ derivatives for highly sensitive fluorescent chemosensors for transition metal ions. A prominent fluorescence enhancement was found in the presence of transition metal ions such as Hg2+ and Cu2+, and this was suggested to result from the suppression of radiationless transitions from the npi state in the chemosensors.

Journal Article↗
PubMed2005

Bicrystalline hematite nanowires.

Bicrystalline nanowires of hematite (alpha-Fe(2)O(3)) have been successfully synthesized by the oxidation of pure iron. The product was characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM in combination with focal series reconstruction, energy-dispersive X-ray spectroscopy, and electron energy-loss spectroscopy. The bicrystalline nanowires have diameters of 20-80 nm and lengths up to 20 microm. All of the investigated materials are found to be alpha-Fe(2)O(3) with a rhombohedral crystal structure. Investigations indicate that most of the bicrystalline nanowires are nanotwins with ellipsoidal heads. The orientation relationship between the nanotwins can be described as (110)(M)//(110)(T), [110](M)//[0](T). An energy-filtered TEM investigation indicates that the ellipsoidal head is iron-rich. The growth mechanism of such unique nanostructures is considered to be a solid-phase growth via surface and internal diffusions of molecules from base to tip.

Journal Article↗
PubMed2005

Microrobotics and MEMS-based fabrication techniques for scaffold-based tissue engineering.

Scaffold based tissue engineering strategies use cells, biomolecules and a scaffold to promote the repair and regeneration of tissues. Although scaffold-based tissue engineering approaches are being actively developed, most are still experimental, and it is not yet clear what defines an ideal scaffold/cell construct. Solid free form fabrication (SFF) techniques can precisely control matrix architecture (size, shape, interconnectivity, branching, geometry and orientation). The SFF methods enable the fabrication of scaffolds with various designs and material compositions, thus providing a control of mechanical properties, biological effects and degradation kinetics. This paper reviews the application of micro-robotics and MEMS-based fabrication techniques for scaffold design and fabrication. It also presents a novel robotic technique to fabricate scaffold/cell constructs for tissue engineering by the assembly of microscopic building blocks.

Biocompatible Materials↗
PubMed2005

Single-crystalline CeB(6) nanowires.

Considered to be one of the best electron emission materials, CeB6 nanowires are of great scientific and industrial interest. CeB6 nanowires of square cross section with about 50 nm in lateral dimension and more than several micrometers in length have been successfully produced using a chemical vapor deposition method. The nanowires are grown in the 100 lattice direction, and both the tip top and the side surfaces are terminated with the {100} lattice planes.

Journal Article↗
PubMed2005

Single-crystalline LaB6 nanowires.

Lanthanum hexaboride nanowires produced by chemical vapor deposition are single-crystalline and grown along the [111] direction. Streaks appearing in the electron diffraction spots indicate the lateral direction perpendicular to the nanowire growth axis.

Journal Article↗
PubMed2005

Experimental demonstration of a nondestructive controlled-NOT quantum gate for two independent photon qubits.

Universal logic gates for two quantum bits (qubits) form an essential ingredient of quantum information processing. However, photons, one of the best candidates for qubits, suffer from a lack of strong nonlinear coupling, which is required for quantum logic operations. Here we show how this drawback can be overcome by reporting a proof-of-principle experimental demonstration of a nondestructive controlled-NOT (CNOT) gate for two independent photons using only linear optical elements in conjunction with single-photon sources and conditional dynamics. Moreover, we exploit the CNOT gate to discriminate all four Bell states in a teleportation experiment.

Journal Article↗
PubMed2005

[Effect of glucocorticoid on neurokinin A in plasma and lungs of guinea pigs with asthma and molecular mechanism of the effect].

OBJECTIVE: Bronchial asthma is a chronic inflammatory disorder of the airways caused by many complicated elements. Recently, a close attention has been paid to the neurogenic inflammation in airways, which is mediated by sensory neuropeptides secreted by sensory nerve. Neurokinin A (NKA) is an important transmitter of non-cholinergic excitatory nerves in the lung which is an important sensory neuropeptide causing airway neurogenic inflammation. The purpose of this study was to investigate the effect of glucocorticoid (dexamethasone) on neurokinin A in plasma and lungs of guinea pigs with asthma and to explore its molecular mechanism. METHODS: Thirty guinea pigs (1.5 months old and weighed 200 - 225 g) were sensitized by exposure to aerosolized ovalbumin and challenged with the same antigen to establish asthma model. These animals were divided randomly into dexamethasone-treatment group and non-dexamethasone-treatment group (15 guinea pigs in each group). Normal control group animals (n = 15) were treated with normal saline (NS) instead of aerosolized ovalbumin. The guinea pigs in the dexamethasone-treatment group were treated with dexamethasone (5.0 mg/kg, intraperitoneal injection) one day before asthma-inducement, on the day of inducement and 24 h after inducement. The non-dexamethasone-treatment group animals were treated with NS (5.0 mg/kg, intraperitoneal injection) on the same days as the dexamethasone-treatment group was treated. The normal control group animals were treated with NS (5.0 mg/kg, intraperitoneal injection). The contents of NKA in the plasma and lung tissues were detected by ELISA; the expression of NKA mRNA in lung tissues was examined by RT-PCR. RESULTS: (1) The contents of NKA in the plasma (2.20 +/- 0.46 ng/ml), lung tissues (5.02 +/- 2.11 ng/g x protein) and the NKA mRNA expression in the lung tissues (1.10 +/- 0.06) of guinea pigs with induced asthma were significantly higher than those of the normal control group (plasma 0.84 +/- 0.33 ng/ml, lung tissues 2.56 +/- 0.80 ng/g x protein, mRNA 0.30 +/- 0.04; P < 0.001, respectively). (2) The contents of NKA in the plasma, lung tissues and the NKA mRNA expression in the lung tissues of guinea pigs with induced asthma were significantly lower in dexamethasone-treatment group (plasma 0.98 +/- 0.23 ng/ml, lung tissues 2.71 +/- 0.50 ng/g x protein, mRNA 0.35 +/- 0.07) than those in the non-dexamethasone-treatment group (plasma 2.20 +/- 0.46 ng/ml, lung tissues 5.02 +/- 2.11 ng/g x protein, mRNA 1.10 +/- 0.06; P < 0.001, respectively). No significant difference was found between the dexamethasone-treatment group and the normal control group (P > 0.05, respectively). CONCLUSIONS: (1) NKA mRNA expression in the lungs of guinea pigs with asthma was up-regulated and NKA contents were higher in plasma and lungs; (2) Glucocorticoid could significantly decrease the contents of NKA in plasma, lung tissues of guinea pigs with induced asthma; the mechanism of the effect may be related to down-regulation of NKA mRNA expression in lung tissues caused by glucocorticoid.

Animals↗
PubMed2005

[Synergic pattern analysis of upper limb grasping movements].

In order to discuss the evaluation method of human upper limb movements, the patterns of movement coordination during healthy people prehension have been researched. Eight subjects were asked to perform different reaching-grasping and drinking water from the cup tasks with different indices of difficulty, and the arm movement trajectories and the main muscles group electromyography (EMG) data were collected. To explore the prehension control mechanism, a comparison has been made between the solution of the theoretic calculation and the experimental data. The results show that the topological invariance was observed in the trajectories of different task performance, and the linear relationships between joints covariation were exhibited. Moreover, the different muscles were controlled and combined into units of synergistic muscular group necessary to reach and grasp the goal.

Adult↗
PubMed2005

[Quantitative gait evaluation using principal component analysis].

Evaluation of human gait function is of great significance in clinical medicine and rehabilitation engineering. A quantitative gait evaluation method using principal component analysis was proposed. The evaluation steps included that a series of characteristic index was performed by the gait parameters with a gait detection, and the index was normalized, quantified and summarized by principal component analysis. Then the evaluation results were shown in formulation, figures and tables. The examples showed that this system could evaluate the recovery of the gait by treatment.

Evaluation Studies as Topic↗
PubMed2004

Sensing of remote oxyanion binding at the DNA binding domain of the molybdate-dependent transcriptional regulator, ModE.

The molybdate-dependent transcriptional regulator ModE of Escherichia coli displays a large (50%) quenching of its intrinsic tryptophan fluorescence on binding molybdate. The changes in fluorescence have been exploited to analyse the binding of molybdate to ModE. Utilising site-directed mutagenesis, a series of phenylalanine substitutions for the three tryptophans of ModE (Trp49, Trp131 and Trp186) have been constructed, to yield three mono-Trp-containing derivatives. This has allowed an assessment to be made of the contribution of each of the three tryptophans to the spectral changes observed on binding molybdate; these are most distinctive for Trp186. Linkage between the DNA-binding and molybdate-binding sites (some 55 angstroms apart) is shown by (a) the small, but definite, effect of molybdate on the fluorescence of Trp49 which is located at the DNA-binding winged helix-turn-helix domain, and (b) the finding that the binding of either ligand is enhanced in the presence of the other. The studies demonstrate that the mono-Trp derivatives of ModE could be useful tools with which to study the signal transduction processes specifically associated with molybdate-dependent transcriptional regulation and that this approach may have wider implications for analysis of other regulated systems.

Amino Acid Sequence↗
PubMed2004

[Raman spectroscopic study on the iron oxide film prepared by iron oxidation method].

Micro-Raman spectroscopy was used to investigate the chemical composition, microstructure and crystalline phase of an iron oxide sample with three-layer macro-structure prepared by iron oxidation. Two laser lines of 514 and 633 nm with a power of 0.5 mW on the sample were employed to excite the Raman spectra. Comparing the sample spectra to that of bulk alpha-Fe2O3, the sample Raman peaks were assigned. And it was found for the top-layer that the Raman frequencies were down shifted and the peak widths broadened. Therefore we verified that the top-layer of the verified sample is a nano-structure alpha-Fe2O3, the main component of the middle-layer is Fe3O4 and the bottom-layer is most like bulk alpha-Fe2O3.

Ferric Compounds↗
PubMed2003

Main inorganic component measurement of seawater using near-infrared spectroscopy.

The potential of near-infrared (NIR) spectroscopy to measure the main inorganic components of seawater as salt-manufacturing materials was investigated. A total of 72 seawater samples collected from six locations was used, and spectra (1100-1800 nm) were acquired by a NIR spectrophotometer with a 1-mm path length. Principal component analysis (PCA), canonical correlation analysis (CCA), and partial least-squares (PLS) regression were performed based on the reference inorganic components. As a result, the principal component analysis and canonical correlation analysis showed that the near-infrared spectra could be related to the inorganic components of seawater. The partial least-squares regression analysis showed that the inorganic components (ion concentration of Cl, Na+, K+, SO4(2-), and Ca2+) could be predicted with good accuracy using NIR spectra and their second derivatives. For Cl ion and K+ ion concentrations, the accuracy was high.

Algorithms↗
PubMed2003

[Toxicity of tetrodotoxin towards mice and rabbits].

The toxicity of tetrodotoxin(TTX) in Kunming mice and rabbits was investigated in this study. The median lethal doses (LD50) were 10.7, 12.5, 532 micrograms/kg for intraperitoneal (i.p.), subcutaneous (s.c.) and intragastric (ig) administration of toxin respectively in mice and, it was found that the male mice was more sensitive to TTX than the female was. TTX toxic doses for both intramuscular (i.m.) and intravenous (i.v.) administration via injection in rabbits were reported first time and the minimal lethal doses(MLD) were 5.3, 3.1 micrograms/kg and wholly lethal doses(LD) were 5.8, 3.8 micrograms/kg for i.m. and i.v. injection respectively. TTX-intoxication symptoms and characteristics were described in both animal species and in different administrations of toxin. TTX was found to be about fifty times less toxic and to have more delayed death occurrence to mice via oral route than that via i.p. injection, providing, more likely, a favorable potential for the cure of actual TTX-poisoning victims.

Animals↗
PubMed2002

Localized neuronal outgrowth induced by long-term sensitization training in aplysia.

Biophysical, biochemical, and morphological studies have implicated sensory neurons as key sites of plasticity in the formation and retention of the memory of long-term sensitization in Aplysia californica. This study examined the effects of different sensitization training protocols on the structure of sensory neurons mediating the tail-siphon withdrawal reflex. A 4 d training period produced a robust localized outgrowth in these sensory neurons observed 24 hr after the end of training. These changes are consistent with previous results in siphon sensory neurons (Bailey and Chen, 1988a). In contrast, 1 d of sensitization training, which has been shown to effectively induce long-term behavioral sensitization and synaptic facilitation (Frost et al., 1985; Cleary et al., 1998), is not associated with morphological changes in tail sensory neurons at either 24 hr or 4 d after training. Similarly, a single treatment with the growth factor TGF-beta, which also induced facilitation, did not alter sensory neuron morphology. The different effectiveness of the two protocols was not simply a reflection of the number of stimuli presented, because a 1 d massed training protocol did not produce sensitization 24 hr after training, nor did it induce neuronal outgrowth. These results suggest that extensive sensitization training is required to induce neuronal outgrowth in tail sensory neurons, indicating that the memory of long-term sensitization induced by 1 d of training is mechanistically different from that induced by 4 d of training. Moreover, the induction of a form of long-term sensitization associated with neuronal outgrowth does not appear to be a function of the amount of stimulation but does appear to be dependent on the temporal spacing of the stimulation over multiple days.

Animals↗
PubMedDate not supplied

Sectional anatomy of the neck.

This is the first in a series of articles structured to provide anatomically accurate functional schematics of the motor and sensory innervation of the face, neck, and trunk. This article provides radiographically oriented cross sections through the neck to assist in identifying clinically significant structures on diagnostic images and for injection procedures. Future articles will present the same information for the face, chest, and abdominal regions, respectively.

Anatomy, Cross-Sectional↗