Biomedical subjects

Gang Zhang

Publications and source records attributed to Gang Zhang.

47 records · Page 3Linked to original sources

PubMed2003

Low-energy (30 keV) carbon ion induced mutation spectrum in the LacZ alpha gene of M13 mp 18 double-stranded DNA.

Double-stranded M13 mp 18 DNA was irradiated with 30 ke V carbon ions in dry state under vacuum to investigate the low-energy heavy ion induced mutation spectra. When the irradiated DNA was used to transfect Escherichia coli JM 105, 3.6-5.7-fold increases in mutation frequency were observed, in contrast to the spontaneous group. Sequences of the 92 induced mutants showed that the carbon ions in this study could induce an interesting mutation spectrum in the lacZ alpha gene. One-base mutations (96.8%) and base pair substitutions (56.4%) were predominant, most of which involved G:C base pairs (90.6%), especially G:C --> T:A transversions (49.6%) and G:C --> A:T transitions (39.6%). This is similar to the spectra induced by gamma-rays in the same ds M13, wild type E. coli system. We also found a considerable amount of carbon ion induced one-base deletion (38.5%) and the mutation sites distribution on the target lacZ alpha gene was obviously non-random. We compared this study with previous data employing gamma-rays to discuss the possible causes of the mutation spectrum.

Base Sequence↗

PubMed2003

Silica nanobottles templated from functional polymer spheres.

Nanosized hollow silica spheres with holes in the wall (denoted as silica nanobottles) have been successfully prepared by assembly of functional polymer nanospheres with tetraethoxysilane (TEOS) through hydrothermal methods, coupled with removal of the core by programmed calcination. The functional polymer nanospheres were obtained by emulsifier-free emulsion copolymerization of styrene and (ar-vinylbenzyl) trimethylammoium chloride. The silica nanobottle sample was characterized by thermogravimetric analysis (TG), differential thermal analysis (DTA), transmission electron microscopy (TEM), and nitrogen adsorption techniques. The above characterizations confirm that the silica nanobottles have holes of about 8 nm in the wall and this unique structural feature might be useful for their encapsulation. Furthermore, characterization by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), and UV-visible absorption (UV-vis) showed that the luminescent material Eu(TTA)(3)(TPPO)(2) could be effectively encapsulated in silica nanobottles. This reveals that silica nanobottles have potential applications for nanotechniques.

Journal Article↗

PubMed2003

Friedländer approach for the incorporation of 6-bromoquinoline into novel chelating ligands.

Nitration of 3-bromobenzaldehyde followed by sodium dithionite reduction provides 5-bromo-2-aminobenzaldehyde, which undergoes the Friedländer condensation with a variety of enolizable ketones to afford bidentate and tridentate 6-bromoquinoline derivatives. These species may be dimerized with Ni(0) to form biquinolines or treated under Sonogashira conditions to afford 6-alkynyl derivatives. Examination of optical properties indicate an unusually high emission quantum yield for 6,6'-biquinolines. [structure: see text]

Journal Article↗

PubMed2003

Differences in membrane association and sub-cellular distribution between NS2-3 and NS3 of bovine viral diarrhoea virus.

The sub-cellular location and mechanism of membrane association of NS3 and NS2-3 polypeptides of bovine viral diarrhoea virus (BVDV) have been examined. Both NS3 and NS2-3 proteins were detected in post-nuclear membrane fractions but not in cytosolic fractions of BVDV infected cells; a proportion of NS3, but not NS2-3, could be dissociated from the membranes with 800 mM KCl or at pH 11. Following extraction with 1% Triton X-114, NS3 was predominantly present in the aqueous phase, but NS2-3 was only recovered in the detergent phase. Confocal microscopy showed that in BVDV infected cells, NS3 and/or NS2-3 co-localise with the endoplasmic reticulum (ER) protein, ERP60, but not Golgi or lysosomal proteins. Sub-cellular fractionation analysis demonstrated that NS2-3 was almost exclusively associated with the rough ER membrane but a significant proportion of NS3 was present in the smooth ER membrane fractions in addition to the rough ER membrane. These differences in the distribution of NS2-3 and NS3 on ER membranes in cells infected with cytopathogenic (CP) strains of BVDV were also observed using confocal microscopy and antibodies that are specific to either NS2 or NS3. This distinct distribution of NS3 and NS2-3 on the ER membrane has revealed a further difference between CP and non-cytopathogenic (NCP) strains of BVDV.

Animals↗

PubMed2003

[Clinical analysis of the patients with burning mouth syndrome].

OBJECTIVE: Clinical data of burning mouth syndrome were investigated in detail and the relation to pain was analyzed in order to find a clue to clinical treatment. METHODS: 78 patients with burning mouth syndrome were examined carefully and 7 factors that related to the degree of pain were analyzed with multivariate stepwise regression. RESULTS: The study demonstrated that the psychological disorder, autonomic nerves system abnormity, oral dryness and high-extravasated blood level were positively related to the degree of pain. CONCLUSION: The study suggested that psychotherapy, improvement of autonomic nerves system, treatment for oral dryness and Chinese traditional therapy of invigoration of blood circulation were of great importance in curing burning mouth syndrome.

Burning Mouth Syndrome↗

PubMed2002

Controlled fabrication of cross-linked nanoparticles/polymer composite thin films through the combined use of surface-initiated atom transfer radical polymerization and gas/solid reaction.

A promising strategy for the controlled synthesis of inorganic/polymeric nanocomposites may be sustained by fabricating cross-linked PbS nanoparticles/polymer composite thin films through combining surface-initiated atom transfer radical polymerization (ATRP) and gas/solid reaction. The introduction of Pb ions through the extension of surface-initiated ATRP to the monomers containing metal ions provides an opportunity for generating nanoparticles on the substrate.

Journal Article↗

PubMed2002

Thin films of Ag nanoparticles prepared from the reduction of AgI nanoparticles in self-assembled films.

A novel method for the preparation of thin films of Ag nanoparticles is reported. Using mercaptoacetic acid as the stabilizing agent, AgI nanoparticles were prepared in aqueous solution. And based on electrostatic interactions, the thiol-passivated AgI nanoparticles were assembled in a self-assembled film by alternative deposition with a cationic polyelectrolyte. Then the AgI nanoparticles in the composite film were reduced by NaBH(4), which resulted in the formation of a thin film of Ag nanoparticles. UV-visible spectra and X-ray photoelectron spectroscopy data confirmed the transformation from AgI to Ag. Atomic force microscopy (AFM) showed that the formed Ag nanoparticles distributed on the film homogeneously. Surface-enhanced Raman spectroscopy (SERS) measurement indicated that the prepared thin films could be used as effective SERS substrates. The reduction process was also carried out by UV light at selective surface regions, which resulted in the formation of patterned nanoparticle arrays.

Journal Article↗

PubMed2002

Fabrication of a covalently attached self-assembly multilayer film based on CdTe nanoparticles.

A precursor film has been fabricated from TGA (thiolglycolic acid)-stabilized CdTe nanoparticles and NDR (nitro-containing diazoresin) using electrostatic interactions and the standard layer-by-layer assembly method; covalent bonds are formed under ultraviolet irradiation. XPS provided evidence for the presence of CdTe nanoparticles within the polymer ultrathin films. UV-visible spectroscopy and FTIR spectroscopy provide evidence for the formation of a covalent linkage. Moreover, the UV-visible spectroscopy and AFM measurement support the improvement of the stability of the hybrid organic/inorganic film toward polar solvents when the linkages between the nanoparticles and polymer changed from ionic bonds to covalent bonds.

Journal Article↗

PubMed2002

The electrical impedance spectroscopy of Scots pine needles during cold acclimation.

The electrical impedance spectroscopy (EIS) was applied to current-year needles of Scots pine (Pinus sylvestris L.) in an 8-year provenance field trial in central Finland during frost hardening. The EIS analysis of the needles using a Model-A equivalent circuit indicated a sequence of events in the needles during their cold acclimation. Some of the EIS-parameters referred to maturation phenomena occurring during the pre-hardening phase at the end of the growing season, and some parameters displayed a clear coincidence with the frost hardening itself. Significant differences between provenances were found in several of the Model-A parameters. Extracellular resistance (re) and beta-coefficient decreased in all provenances in the pre-hardening phase in August and until mid-September. In the same phase, both the intracellular resistance (ri) and the cell membrane time constant (taum) first increased and then decreased. According to taum, re and beta there was a clear gradation between provenances in the pre-hardening phase. From the end of September significant differences were found in the intracellular resistance between provenances, corresponding with the differences in their hardening pattern. The dry weight (DW) content of needles increased during the study period but no clear differences were found between the provenances.

Journal Article↗

PubMed2002

Inhibition of beta interferon transcription by noncytopathogenic bovine viral diarrhea virus is through an interferon regulatory factor 3-dependent mechanism.

The induction and inhibition of the interferon (IFN) response and apoptosis by bovine viral diarrhea virus (BVDV) has been examined. Here we show that prior infection of cells by noncytopathogenic BVDV (ncp BVDV) fails to block transcriptional responses to alpha/beta IFN. In contrast, ncp BVDV-infected cells fail to produce IFN-alpha/beta or MxA in response to double-stranded RNA (dsRNA) or infection with a heterologous virus (Semliki Forest virus [SFV]). ncp BVDV preinfection is unable to block cp BVDV- or SFV-induced apoptosis. The effects of ncp BVDV infection on the transcription factors controlling the IFN-beta induction pathway have been analyzed. The transcription factor NF-kappa B was not activated following ncp BVDV infection, but ncp BVDV infection was not able to block the activation of NF-kappa B by either SFV or tumor necrosis factor alpha. Furthermore, ncp BVDV infection did not result in the activation of stress kinases (JNK1 and JNK2) or the phosphorylation of transcription factors ATF-2 and c-Jun; again, ncp BVDV infection was not able to block their activation by SFV. Interferon regulatory factor 3 (IRF-3) was shown to be translocated to the nuclei of infected cells in response to ncp BVDV, although DNA-binding of IRF-3 was not seen in nuclear extracts. In contrast, an IRF-3-DNA complex was observed in nuclear extracts from cells infected with SFV, but the appearance of this complex was blocked when cells were previously exposed to ncp BVDV. We conclude that the inhibition of IFN induction by this pestivirus involves a block to IRF-3 function, and we speculate that this may be a key characteristic for the survival of pestiviruses in nature.

Animals↗

PubMed2002

Mechanical properties of hepatocellular carcinoma cells.

AIM: To study the viscoelastic properties of human hepatocytes and hepatocellular carcinoma (HCC) cells under cytoskeletal perturbation, and to further to study the viscoelastic properties and the adhesive properties of mouse hepatoma cells (HTC) in different cell cycle. METHODS: Micropipette aspiration technique was adopted to measure viscoelastic coefficients and adhesion force to collagen coated surface of the cells. Three kinds of cytoskeleton perturbing agents, colchicines (Col), cytochalasin D (CD) and vinblastine (VBL), were used to treat HCC cells and hepatocytes and the effects of these treatment on cell viscoelastic coefficients were investigated. The experimental results were analyzed with a three-element standard linear solid. Further, the viscoelastic properties of HTC cells and the adhesion force of different cycle HTC cells were also investigated. The synchronous G(1) and S phase cells were achieved through thymine-2-desoryriboside and colchicines sequential blockage method and thymine-2-desoryriboside blockage method respectively. RESULTS: The elastic coefficients, but not viscous coefficient of HCC cells (K(1)=103.6+/-12.6N.m(-2), K(2)=42.5 +/ 10.4N.m(-2), mu=4.5 +/- 1.9Pa.s), were significantly higher than the corresponding value for hepatocytes (K(1)=87.5 +/- 12.1N.m(-2), K(2)=33.3+/-10.3N.m(-2), mu=5.9+/-3.0Pa.s, P<0.01). Upon treatment with CD, the viscoelastic coefficients of both hepatocytes and HCC cells decreased consistently, with magnitudes for the decrease in elastic coefficients of HCC cells (K(1): 68.7 N.m(-2) to 81.7N.m(-2), 66.3% to 78.9%; K(2): 34.5N.m(-2) to 37.1N.m(-2), 81.2% to 87.3%, P<0.001) larger than those for normal hepatocytes (K(1): 42.6N.m(-2) to 49.8N.m(-2), 48.7% to 56.9%; K(2): 17.2N.m(-2) to 20.4N.m(-2), 51.7% to 61.3%, P<0.001). There was a little decrease in the viscous coefficient of HCC cells (2.0 to 3.4Pa.s, 44.4 to 75.6%, P<0.001) than that for hepatocytes (3.0 to 3.9Pa.s, 50.8 to 66.1% P<0.001). Upon treatment with Col and VBL, the elastic coefficients of hepatocytes generally increased or tended to increase while those of HCC cells decreased. HTC cells with 72.1% of G(1) phase and 98.9% of S phase were achieved and high K(1), K(2) value and low mu value were the general characteristics of HTC cells. G(1) phase cells had higher K(1) value and lower mu value than S phase cells had, and G(1) phase HTC cells had stronger adhesive forces ((275.9 +/- 232.8) x 10(-10)N) than S phase cells ((161.2 +/- 120.4) x 10(-10)N, P<0.001). CONCLUSION: The difference in both the pattern and the magnitude of the effect of cytoskeletal perturbing agent on the viscoelastic properties between HCC cells and hepatocytes may reflect differences in the state of the cytoskeleton structure and function and in the sensitivity to perturbing agent treatment between these two types of cells. Change in the viscoelastic properties of cancer cells may affect significantly tumor cell invasion and metastasis as well as interactions between tumor cells and their micro-mechanical environments.

Animals↗